CN102612861A - Light-emitting diode drive device and light-emitting diode illumination control method - Google Patents

Abstract

Disclosed is a light-emitting diode drive device that improves the utilization efficiency and power factor of LEDs while maintaining power supply efficiency. Said light-emitting diode drive device is provided with: a rectification circuit (2) that can be connected to an AC power supply and rectifies the AC voltage from said AC power supply into a pulsed voltage; a first LED block (11) comprising a plurality of light-emitting diodes, a second LED block (12) comprising a plurality of light-emitting diodes, and a third LED block (13) comprising a plurality of light-emitting diodes, connected sequentially in series to the output side of the rectification circuit (2); a first switching means that turns a first bypass path (BP1), which bypasses the second LED block (12), on or off on the basis of the amount of power supplied to the first LED block (11); and a second switching means that turns a second bypass path (BP2), which bypasses the third LED block (13), on or off on the basis of the amount of power supplied to the first LED block (11) and the second LED block (12).

Description

The lighting control method of light emitting diode drive device and light-emitting diode

Technical field

The present invention relates to light-emitting diode is lighted the drive circuit of driving and the lighting control method of light-emitting diode, particularly use the light emitting diode drive device that AC power drives and the lighting control method of light-emitting diode.

Background technology

In recent years, as illuminating light source, compare with incandescent lamp bulb or fluorescent lamp the light-emitting diode that can drive with low power consumption (below be also referred to as " LED ".) attracted attention.The advantage of LED is: small-sized and resistance to impact is strong, needn't worry that lamp body breaks.

As the power supply that this lighting apparatus is used, the interchange of hope employing domestic power supply etc. is as power supply.On the other hand, LED is the DC driven element, and is only luminous under the electric current of forward.In addition, the forward voltage Vf as the LED of the current most employing of lighting use is about 3.5V.LED has following characteristic: if do not reach Vf then not luminous, then flow through excessive electric current if surpass Vf on the contrary.Therefore, for LED, we can say based on the driving of direct current more suitable.

In order to tackle this opposite condition, the drive circuit of the LED of various employing AC powers has been proposed.For example, in drive circuit shown in Figure 8, carry out full-wave rectification with 72 pairs of AC powers ofbridge circuit 71, bysmmothing capacitor 73 carry out level and smooth after, come drivingLED group 75 with thedrive circuit 74 of constant current circuit or switching power circuit etc.In this circuit, height is withstand voltage, the characteristic requirements of high capacitance owing to the smmothingcapacitor 73 to level and smooth usefulness has, and therefore needs large-scale elements such as aluminium electrolytic capacitor.In addition, there is short problem of life-span in general electrolytic capacitor under the temperature condition with higher around.Have again, have the problem of the performance degradation under maximization and the high temperature for the coil of using in the Switching Power Supply too.On the other hand, in switching power circuit,, therefore also need the noise countermeasure because the big electric current of speed-sensitive switch is easy to generate noise.Like this, in existing drive circuit, there is following problem: need guarantee to use the configuration space of the element in the drive circuit of the LED that should be suitable for miniaturization, need be used to reduce the structure of temperature effect, also need the noise countermeasure.

To this problem following method has been proposed, for improve and LED between compatibility, do not carry out smoothing, but drive with constant current circuit etc. by the voltage waveform after the bridge circuit rectification.This circuit example has been shown among Fig. 9.Drive circuit shown in this figure is identical with Fig. 8, after carrying out full-wave rectification with 82 pairs of AC powers ofbridge circuit 81, does not carry out smoothing, but comes drivingLED group 85 through the constantcurrent circuit 84 that is made up of transistor and resistance.Constantcurrent circuit 84 is made up offeedback resistance 86, current detectingtransistor 87,current control transistor 88, current sense resistor 89.Because this circuit is to be made up of semiconductor element, we can say that therefore with identical semiconductor element be that operating temperature range between the LED is common, be suitable for miniaturization.

But during driving LED, its voltage waveform becomes that kind shown in Figure 10 not carrying out smoothing, its magnitude of voltage cyclic variation but not steady state value.On the other hand, the connection because each LED that kind as shown in Figure 9 is one another in series, as long as therefore apply the aggregate value that voltage does not surpass the forward voltage Vf of LED, LED just can not light.Therefore, in the voltage waveform that changes in this time shown in Figure 10, the The limited time that exists LED to light, thereby the problem that the utilization ratio of LED descends.At this, the utilization ratio of so-called LED is represented by (the effective power consumption of LED)/(the LED power consumption when dc rated current drives).

Especially, in series inserting in the circuit of current-limiting resistance with LED in order to protect LED, with respect to mains fluctuations, the electric power of LED also has very great fluctuation process, also can surpass the LED rated current sometimes, therefore, needs in advance current settings to be got less.Therefore, generally constituting constant current circuit in this case drives.If the problem to this moment is described in detail, for example the 100V of the source power supply of Japan is an effective value, and the maximum voltage after the full-wave rectification is 141V.LED is being connected in this power supply; Under the situation about driving with constant current circuit,, and adopt constant current circuit to drive if only connect the LED of a Vf=3.5V; Then be in ON at supply voltage above LED in the scope of 3.5V, the LED utilization ratio uprises.But such shown in shade in the voltage waveform of Figure 11, the major part of electric power is consumed as heat, and be not used to luminous, its as a result power-efficient reduce greatly.

On the other hand, also consider to increase the number of connection of LED, make a plurality of LED be connected in series, thereby the aggregate value of forward voltage Vf approaches 141V.At this moment, be about 90% if want to guarantee power-efficient, the aggregate value that then needs Vf is about 120V.But LED just becomes ON in supply voltage surpasses the scope of 120V in this design, and LED can not light below it, and its result only lights in the scope shown in the dotted line in Figure 11, is about 35% as the ON duty ratio.Therefore, the LED utilization ratio also is about 35%, and power factor is about 77%.Like this, if reduce Vf in order to improve the LED utilization ratio, then can be increased by the idle work of heat exhaustion, if opposite improve power-efficient and improve Vf, then the ON duty ratio of LED shortens, and the LED utilization ratio worsens, and has the problem of this contradiction.

Moreover, proposed to switch the method (patent documentation 1) of LED according to the mode that changes the aggregate value of Vf according to the magnitude of voltage that changes.In the method; Shown in the circuit diagram of Figure 12; The LED that plural serial stage is connected is divided intopiece 61,62,63,64,65,66; The connection of switchingLED piece 61～66 according to the magnitude of voltage of the input voltage of rectified waveform through theswitch control part 67 that constitutes by microcomputer, thus the aggregate value of Vf changed interimly.Its result, voltage waveform shown in the sequential chart of Figure 13 is such, can light LED with a plurality of rectangular waves with respect to rectified waveform, therefore with this only single rectangular wave of Figure 11 under the ON duty ratio compare, can improve the utilization ratio of LED.But in the method, the result who obtains based on the magnitude of voltage that detects the input waveform uses microcomputer in order to switch each LED piece side by side, can carry out high-precision control, but antimetrical circuit constitutes the costliness that becomes, can't be towards the lighting device of cheapness.

Have again, also proposed shown in the circuit diagram of Figure 14 suchly not use microcomputer and detect the structure of voltage by Zener diode and resistance.Circuit shown in this figure is based on by the magnitude of voltage after Zener diode 94 and resistance 95 dividing potential drops; The connection of switching LED piece 91,92,93 according to the magnitude of voltage of the input voltage of rectified waveform; Change the aggregate value of Vf interimly; Its result is such shown in the voltage waveform of Figure 15, can light LED with a plurality of rectangular waves with respect to rectified waveform.Circuit than Figure 12 constitutes, and the advantage of this structure is and can constitutes with the mode of cheapness.

But, in above-mentioned any means, owing to be to switch the structure of lighting between the LED piece, therefore need correctly make this switched voltage value consistent with the Vf value (during the setting electric current) of LED piece at different levels according to the input voltage after the rectification.Yet generally can there be characteristic deviation in the LED element, and Vf and temperature characterisitic are different for each element, so this correct adjustment is very difficult in the reality.Particularly shown in figure 13, because each LED piece need be with connections that be one another in series of a plurality of LED elements, so the deviation of the Vf of each element result of addition step by step, the deviation of the Vf magnitude of voltage of LED piece integral body can become bigger.On the other hand, also consider and only use the LED element of selecting in advance in order to suppress deviation, but the cost of LED element rises in this case, and rate of finished products also worsens.In lighting device, use a plurality of LED elements especially, in order to popularize LED lighting device strong request cutting down cost, therefore such selection is unpractical on the other hand.

Therefore, the Vf of each LED piece departs from the result of desired value, if the Vf value becomes and is higher than the switched voltage value, does not have electric current to flow through after then just having switched, and LED is lighted, and brings the generation of noise and power factor to descend.On the contrary, when the Vf of LED becomes when being lower than the switched voltage value, its corresponding electric power is consumed by constant current circuit without rhyme or reason.Therefore, realize that according to the deviation of LED element the action of hoping is a difficulty comparatively, its result can produce the delay of lighting switching, the decline of efficient, in reality, lights at LED to be difficult to realize aspect quality and the reliability.

Have, although the switching through the LED piece can make LED be in ON with a plurality of rectangular waves in said method, therefore such residual electric power that is not consumed shown in the oblique line of Figure 15 exist the still not good enough shortcoming of efficient again.

Special in the highest zone of voltage, existence can't effectively utilize the original problem that can make LED carry out the brightest luminous zone.

Summary of the invention

The present invention proposes in view of this background; Its main purpose is to provide the lighting control method of a kind of light emitting diode drive device and light-emitting diode; Can keep higher power-efficient; Improve LED utilization ratio and power factor simultaneously, can absorb the forward voltage Vf of employed each LED element and the deviation of temperature characterisitic in addition, can stably move.

The method and invention effect that are used for the technical solution problem

In order to realize the above object, the light emitting diode drive device related according to the 1st side, it possesses:rectification circuit 2, it can be connected with AC power, is used to obtain alternating voltage to this AC power and carries out the pulsating voltage after the rectification; ALED piece 11 that is connected in series successively with the outlet side of saidrectification circuit 2, constitutes by a plurality of light-emitting diodes, the2nd LED piece 12 that constitutes by a plurality of light-emitting diodes, the3rd LED piece 13 that constitutes by a plurality of light-emitting diodes; First switch unit, it is based on the energising amount of a saidLED piece 11, switches to make said the2nd LED piece 12 become the ON/OFF of the first bypass path BP1 of bypass; With second switch unit, it is based on the energising amount of a saidLED piece 11 and said the2nd LED piece 12, switches to make said the3rd LED piece 13 become the ON/OFF of the second bypass path BP2 of bypass.Thus, because can therefore can effectively utilize electric power, thereby improve LED utilization ratio and power factor based on the energising amount of LED piece is switched the energising amount to each LED piece with the variation of pulsating voltage is irrelevant.

In addition, the light emitting diode drive device related according to the 2nd side, said first switch unit has: firstcurrent control unit 21, itself and said the2nd LED piece 12 are connected in parallel, and are used to limit the energising amount to a saidLED piece 11; The first current detecting control unit 31, it is used to control the energising limit amount by 21 pairs of saidLED pieces 11 of said first current control unit; With the firstcurrent detecting unit 4B; Itself and a saidLED piece 11 are connected in series; Detect the energising amount of a saidLED piece 11; Said second switch unit has: secondcurrent control unit 22, and itself and said the3rd LED piece 13 are connected in parallel, and are used to limit the energising amount to a saidLED piece 11 and said the2nd LED piece 12; The second currentdetecting control unit 32, it is used to control the energising limit amount by 22 pairs of saidLED pieces 11 of said second current control unit and the2nd LED piece 12; With the second current detectingunit 4C, itself and said the2nd LED piece 12 are connected in series, and detect the energising amount of said the 2nd LED piece 12.Thus, can switch energising amount, promptly light/extinguish, therefore, can irrespectively effectively utilize electric power, thereby improve LED utilization ratio and power factor with the variation of pulsating voltage to the LED piece through current control unit and current detecting control unit.

Have, the light emitting diode drive device related according to the 3rd side makes the said first current detectingunit 4B and the second current detectingunit 4C shared again.Thus, because first, second current detecting control unit is controlled the energising amount to LED piece or current control unit respectively based on common energising amount,, can simplify circuit and constitute so do not need special-purpose current detecting unit is set separately.

In addition, the light emitting diode drive device related according to the 4th side, it possesses:rectification circuit 2, it can be connected with AC power, is used to obtain the pulsating voltage to after the ac voltage rectifier of this AC power; The oneLED piece 11, it is made up of a plurality of light-emitting diodes that the outlet side with saidrectification circuit 2 is connected in series; The2nd LED piece 12, it is made up of a plurality of light-emitting diodes that are connected in series with a saidLED piece 11; The3rd LED piece 13, it is made up of a plurality of light-emitting diodes that are connected in series with said the2nd LED piece 12; Current limliting unit 3, itself and said the3rd LED piece 13 are connected in series; Firstcurrent control unit 21, itself and said the2nd LED piece 12 are connected in parallel, and are used to limit the energising amount to a saidLED piece 11; Secondcurrent control unit 22, itself and said the3rd LED piece 13 are connected in parallel, and are used to limit the energising amount to a saidLED piece 11 and said the2nd LED piece 12; The 3rdcurrent control unit 23, itself and said current limliting unit 3 are connected in parallel, and are used to limit the energising amount to a saidLED piece 11, the2nd LED piece 12 and said the3rd LED piece 13; The first current detecting control unit 31, it is used to control the energising limit amount by 21 pairs of saidLED pieces 11 of said first current control unit; The second current detectingcontrol unit 32, it is used to control the energising limit amount by 22 pairs of saidLED pieces 11 of said second current control unit and the2nd LED piece 12; With the 3rd currentdetecting control unit 33, it is used to control the energising limit amount by the saidLED piece 11 of 23 pairs of said the 3rd current control units, the2nd LED piece 12 and the 3rd LED piece 13.Thus, because based on the energising amount of LED piece being switched energising amount, is promptly lighted/extinguish to each LED piece, thus can irrespectively effectively utilize electric power with the variation of pulsating voltage, thus LED utilization ratio and power factor can be improved.In addition, owing to control lighting of LED, therefore can realize not relying on the only action of deviation of forward voltage Vf and the temperature characterisitic of each LED element through Current Control.Have again, do not need complicated control can simplify circuit and constitute, can obtain the high LED drive unit of cheapness and reliability.In addition, also can obtain to suppress the effect that noise produces.

In addition; The light emitting diode drive device related according to the 5th side; Can be set at energising limit amount by 21 pairs of saidLED pieces 11 of said first current control unit less than energising limit amount by 22 pairs of saidLED pieces 11 of said second current control unit and the2nd LED piece 12, by the energising limit amount of 22 pairs of saidLED pieces 11 of said second current control unit and the2nd LED piece 12 less than energising limit amount by the saidLED piece 11 of 23 pairs of said the 3rd current control units, the2nd LED piece 12 and the 3rd LED piece 13.Thus, after a LED piece becomes ON, the 2nd LED piece is switched to ON earlier, then the 3rd LED piece is switched to ON, can be according to this order lighting of conversion LED piece successively.In addition, for the current value that flows through in the LED piece, then suppress its current value low more, therefore can suppress caloric value, thereby improve the life characteristic of light-emitting diode owing to light long more LED piece of time.

In addition; The light emitting diode drive device related according to the 6th side; Said light emitting diode drive device also possesses the current detecting unit 4 that between said current limliting unit 3 and ground wire, is connected; The said first current detecting control unit 31, the second currentdetecting control unit 32, the 3rd currentdetecting control unit 33 be based on the energising amount of said current detecting unit 4, limits the energising amount to a saidLED piece 11, the2nd LED piece 12, the3rd LED piece 13 respectively.Thus, because each current detecting control unit is controlled the energising amount to LED piece or current control unit respectively based on common energising amount,, can simplify circuit and constitute so do not need special-purpose current detecting unit is set separately.

Have, the light emitting diode drive device related according to the 7th side also possesses the capacitor that between the outlet side of said rectification circuit and ground wire, is connected again.Thus, can avoid the so-called stroboscopic phenomenon that light-emitting diode all extinguishes in the lower zone of pulsating voltage.

In addition, according to the lighting control method of the related light-emitting diode in the 8th side, it comprises: obtain AC power is carried out rectification pulsating voltage afterwards; This pulsating voltage is put on a LED piece, the 2nd LED piece, the 3rd LED piece that is connected in series each other, a plurality of light-emitting diodes are one another in series and connect; Make the 2nd LED piece become first current control unit of ON/OFF of first bypass path of bypass thereby can switch is connected in parallel with said the 2nd LED piece; Energising amount based on a said LED piece; In this energising amount is that setting switches to ON with first bypass path when following, when this energising amount surpasses setting, first bypass path is switched to OFF; Thereby switched under the state that said the 2nd LED piece of OFF is energized at said first bypass path; Make the 3rd LED piece become second current control unit of ON/OFF of second bypass path of bypass thereby can switch is connected in parallel with said the 3rd LED piece; Energising amount based on said the 2nd LED piece; In this energising amount is that setting switches to ON with second bypass path when following, when this energising amount surpasses setting, second bypass path is switched to OFF.Thus, because based on the energising amount of LED piece being switched energising amount, is promptly lighted/extinguish to each LED piece, thus can irrespectively effectively utilize electric power with the variation of pulsating voltage, thus LED utilization ratio and power factor can be improved.In addition, owing to control lighting of LED, therefore can realize not relying on the only action of deviation of forward voltage Vf and the temperature characterisitic of each LED element through Current Control.Have again, do not need complicated control can simplify circuit and constitute, can obtain the high LED drive unit of cheapness and reliability.In addition, also can obtain to suppress the effect that noise produces.

In addition.Lighting control method according to the related light-emitting diode in the 9th side; Thereby also comprise the steps: to be switched under the state that said the 3rd LED piece of OFF is energized at said second bypass path; Make this current limliting unit become the 3rd current control unit of ON/OFF of the 3rd bypass path of bypass thereby can switch is connected in parallel with the current limliting unit that is connected in series in said the 3rd LED piece; Energising amount based on said the 3rd LED piece; In this energising amount is that setting switches to ON with the 3rd bypass path when following, when this energising amount surpasses setting, the 3rd bypass path is switched to OFF.

Description of drawings

Fig. 1 is the block diagram of the related light emitting diode drive device ofexpression execution mode 1.

Fig. 2 is the circuit diagram of the related light emitting diode drive device ofexpression embodiment 1.

Fig. 3 is the curve of the current waveform of expression when inputing to pulsating voltage in the circuit of Fig. 2.

Fig. 4 is the curve of the current waveform of the related light emitting diode drive device ofexpression embodiment 2.

Fig. 5 is the circuit diagram of the related light emitting diode drive device of expression embodiment 3.

Fig. 6 is the circuit diagram of the related light emitting diode drive device of expression embodiment 4.

Fig. 7 is the circuit diagram of the related light emitting diode drive device ofexpression embodiment 5.

Fig. 8 is the block diagram of the existing led drive circuit of expression.

Fig. 9 is the block diagram of existing other led drive circuits of expression.

Figure 10 is the curve of expression to the waveform of the pulsating voltage after the ac voltage rectifier.

Figure 11 is the curve of expression based on the LED driving voltage of full-wave rectifier power supply.

Figure 12 is the circuit diagram that the LED point brightening circuit example of microcomputer is used in expression.

Figure 13 is the sequential chart of action of the LED point brightening circuit of expression Figure 12.

Figure 14 is the routine circuit diagram of LED point brightening circuit of representing not use microcomputer.

Figure 15 is the sequential chart of action of the LED point brightening circuit of expression Figure 14.

Figure 16 is the circuit diagram that the light emitting diode drive device of film capacitor is used in expression.

Figure 17 is the curve of input voltage waveform in the circuit of expression Figure 16.

Figure 18 is the curve of expression based on the time variation of the light beam of the circuit of Figure 16.

Figure 19 is the circuit diagram of the related light emitting diode drive device of expression embodiment 6.

Figure 20 is the curve of input voltage waveform in the circuit of expression Figure 19.

Figure 21 is the curve of expression based on the time variation of the light beam of the circuit of Figure 19.

Embodiment

Below, based on description of drawings execution mode of the present invention.But; Below shown in the execution mode illustration be used for specializing the light emitting diode drive device of technological thought of the present invention and the lighting control method of light-emitting diode, the present invention is not that the lighting control method with light emitting diode drive device and light-emitting diode is defined as following content.In addition, this specification is not the parts that the parts shown in the claim are defined as execution mode.The size of the component parts of particularly putting down in writing in the execution mode, material, shape, its relative short of specific record such as configuration are not scope of the present invention to be defined in this meaning just, and only are illustrative examples.Moreover in order to describe clearly, the size of the parts shown in each drawing and position relation etc. is exaggerated sometimes.Have again, in following explanation, for same title, symbol, represent the parts of identical or homogeneity, suitably omit its detailed description.Having, for formation each key element of the present invention, thereby also can be to constitute the mode of a plurality of key elements with a plurality of key elements of parts dual-purpose by same parts again, on the contrary, also can share a functions of components by a plurality of parts and realize.In addition, the content of in the embodiment of a part, execution mode, explaining also can be used among other embodiment, execution mode etc. sometimes.

Fig. 1 representes the block diagram of the light emitting diode drive device that execution mode is related.Light emittingdiode drive device 100 shown in this figure is connected with AC power AP, will be used to obtain therectification circuit 2 of the pulsating voltage (pulsating current voltage) after the ac voltage rectifier,LED piece group 1, current limliting unit 3, the current detecting unit 4 that is made up of a plurality of LED pieces are connected in series respectively.At this, use three LED pieces, aLED piece 11, the2nd LED piece 12, the3rd LED piece 13 are connected in series and constitute LED piece group 1.Moreover, in this manual, so-called key element " series connection " is connected, short of special provision, the order of just not considering to connect is how, and the form of the key element of in addition insertion therebetween being appended is as long as keep in the type of attachment of series connection is also included within.For example; Except the order according to aLED piece 11, the2nd LED piece 12, the3rd LED piece 13, current limliting unit 3, current detecting unit 4 connects, can also connect according to the order of aLED piece 11, the2nd LED piece 12, current detecting unit 4, the3rd LED piece 13, current limliting unit 3.

In addition, at the2nd LED piece 12, the3rd LED piece 13, two ends separately, current limliting unit 3, connect the current control unit that is used to limit the energising amount.Because each current control unit is provided with respect to LED piece or current limliting unit 3 respectively side by side, therefore constitute the bypass path of adjustment energising amount.That is, owing to can adjust by the magnitude of current of each current control unit bypass, so the result can limit the energising amount of each LED piece.In the example of Fig. 1, be connected firstcurrent control unit 21 with the2nd LED piece 12 parallelly connectedly, form the first bypass path BP1.In addition, be connected secondcurrent control unit 22 parallelly connectedly, form the second bypass path BP2 with the 3rd LED piece 13.Have again, be connected the 3rdcurrent control unit 23 parallelly connectedly, form the 3rd bypass path BP3 with current limliting unit 3.

Moreover in the example of Fig. 1, current limliting unit 3 uses the LED current-limiting resistance as resistor, plays a role as the protective resistance of LED.In addition, current detecting unit 4 also can use resistor, is detected based on the voltage degradation by this current detecting unit 4 the LED piece is connected in series and the electric current that flows through in theLED piece group 1 that obtains, constitutes the constant current driven of the LED element of LED piece.In addition,, the current detecting control unit is set, is used to control constant current circuit in order to carry out constant current driven.In this circuit example, constitute a kind of constant current circuit by current control unit and current detecting control unit.

The current detecting control unit is connected with current control unit, the ON/OFF of Control current control unit and this action of magnitude of current continuous variable.Particularly, be provided with the 3rd currentdetecting control unit 33 of action of the second currentdetecting control unit 32, control the 3rdcurrent control unit 23 of action of the first current detecting control unit 31, control secondcurrent control unit 22 of the action of control first current control unit 21.Each current detecting control unit is kept watch on the magnitude of current of LED, based on the controlled quentity controlled variable of its value switch current control unit.

The LED piece is series connection and/or is connected in parallel a plurality of LED elements and the piece that obtains.The LED element can suitably utilize the LED of surface installing type (SMD) and ball-type.In addition, the packaging appearance of the LED element of SMD type can be selected, the type of overlooking can be utilized to rectangular shape according to purposes.Have again, can certainly and/or be connected in parallel a plurality of LED elements and the LED that obtains is used as the LED piece series connection in encapsulation.

The additive value of the forward voltage of the LED element that comprises in each LED piece promptly amounts to forward voltage, decides according to the number of LED coupled in series element.Total forward voltage when for example, using the LED element of 8 forward voltage 3.6V is 3.6 * 8=28.8V.But, because there is characteristic deviation in each individuality of LED element, therefore generally neither be constant as the total forward voltage of its additive value.Therefore, also there is deviation in the total forward voltage of each LED piece.

This light emittingdiode drive device 100 switches the ON/ constant current control/OFF to the energising of each LED piece based on current detecting unit 4 detected current values.In other words; Owing to be based on the Current Control of the magnitude of current that passes through in the reality; Rather than based on the Current Control of the magnitude of voltage of commutating voltage; Therefore can not receive the influence of the forward voltage deviation of LED element, can realize the switching of correct LED piece, can expect the stable action that reliability is high according to appropriate timing.

Particularly, in the example of Fig. 1, the first current detecting control unit 31 is controlled the energising limit amount of 21 pairs the oneLED pieces 11 of first current control unit based on the energising amount of a LED piece 11.Particularly, when the energising amount is higher than predefined first reference current value, the2nd LED piece 12 is switched to ON, get into the constant current action, when being lower than first reference current value, switch to OFF.Have again; The second current detectingcontrol unit 32 is based on the energising amount of the2nd LED piece 12; Switch the ON/ constant current control/OFF of the2nd LED piece 12 according to predefined second reference current value, so that control the energising limit amount of 22 pairs the2nd LED pieces 12 of second current control unit.Equally; The 3rd currentdetecting control unit 33 is also based on the energising amount of the3rd LED piece 13; Switch energising ON/ constant current control/OFF according to predefined the 3rd reference current value, so that control the energising limit amount of 23 pairs the3rd LED pieces 13 of the 3rd current control unit to the3rd LED piece 13.

At this, through being set at first reference current value＜second reference current value＜the 3rd reference current value, can be according to switching ON/ constant current control/OFF successively from the order of aLED piece 11 the2nd LED piece 12, the3rd LED piece 13, current limliting unit 3.

As above-mentioned; Light emitting diode drive device possesses a plurality of constant current circuits; These a plurality of constant current circuits constitute: the AC power of utilizing domestic power supply etc.; With it is exchanged the periodically variable pulsating voltage that carries out obtaining after the full-wave rectification matchingly, light the LED element of the configured in series of suitable number so that each constant current circuit respectively suitably the mode of action a plurality of LED current detection circuits are moved.

Like this; Light emitting diode drive device makes 11 energisings of 1LED piece with the 1st current value; Make1LED piece 11 and 12 energisings of 2LED piece with the 2nd current value, and then make1LED piece 11,2LED piece 12,13 energisings of 3LED piece with the 3rd current value greater than the 2nd current value greater than the 1st current value.Especially, control the energising amount that limits each LED piece, can switch the ON/ constant current control/OFF of LED piece, can light driving LED effectively to pulsating voltage according to the magnitude of current through constant current.

Moreover the LED piece can constitute respectively the connection that is one another in series of a plurality of light-emitting diodes.Thus, can carry out dividing potential drop with a plurality of light-emitting diodes to pulsating voltage effectively, can absorb the forward voltage Vf of each light-emitting diode and the deviation of temperature characterisitic to a certain extent, can make with the piece is the control homogenization of unit.But; For the quantity of LED piece or constitute light-emitting diode number of each LED piece etc.; Can set arbitrarily according to desired brightness and input voltage etc.; For example both can constitute the LED piece, thereby the quantity that increases the LED piece is carried out more careful control, thereby perhaps on the contrary the LED piece is set at only 2 simplification controls by a light-emitting diode.

(embodiment 1)

Next, asembodiment 1, the concrete circuit that adopts semiconductor element to realize the structure of Fig. 1 has been shown in Fig. 2 has constituted example.In the light emittingdiode drive device 200 shown in this figure, adopt diode bridge as the rectification circuit that is connected with AC power AP 2.In addition, between AC power AP andrectification circuit 2,protective resistance 17 is set.Have again, at the outlet side connection by-pass capacitor 19 ofrectification circuit 2.

(AC power AP)

AC power AP can suitably utilize the source power supply of 100V.The 100V of this source power supply is an effective value, is about 141V by the maximum voltage of the rectified waveform after the full-wave rectification.

(LED piece)

Each LED piece is connected in series each other, and is divided into a plurality of, from piece border leading-out terminal each other, is connected with current control unit.In the example of Fig. 2, constituteLED piece group 1 by three groups of aLED piece 11, the2nd LED piece 12, the 3rd LED piece 13.Moreover, in Fig. 2, represent each LED piece, but each LED piece is connected in series a plurality of light-emitting diodes and constitutes with a LED.The light-emitting diode number of connection of each LED piece or the number of connection of LED piece are that the sum and the employed supply voltage of LED coupled in series element decides by the additive value of forward voltage.For example using under the situation of source power supply, the total of the Vf of each LED piece promptly add up to forward voltage Vfall be set to about 141V, or below it.

Moreover in the example of Fig. 2, the Vf that is designed to three LED pieces is identical.But, be not limited to this example, also can LED piece number be set at more than 2 or 4.Have, the Vf of each LED piece also can be inequality again.

(current control unit)

Current control unit is the parts that are used to carry out constant current driven corresponding to each LED piece.As this current control unit, constitute by the switch element of transistor etc.Especially,, therefore can not hinder energising amount, preferably constitute by FET to the LED piece because saturation voltage is roughly zero between source electrode-drain electrode of FET.But, current control unit is not limited to FET, also can be made up of bipolar transistor or comparator, operational amplifier, variable resistor etc. certainly.

In the example of Fig. 2,, use FET as the LED current control transistor that constitutes current control unit.In this FET, between gate terminal and source terminal, be connected the gate protection Zener diode respectively.Particularly; Between the gate-to-source of a LEDcurrent control transistor 21A, connect first gridprotection Zener diode 24; Between the gate-to-source of the 2nd LEDcurrent control transistor 22A, connect second gridprotection Zener diode 25, between the gate-to-source of the 3rd LEDcurrent control transistor 23A, connect the 3rd gateprotection Zener diode 26.

In addition, the gate terminal at each LED current control transistor connects resistance respectively.Particularly; Gate terminal at a LEDcurrent control transistor 21A connectsfirst grid resistance 27; Connectsecond grid resistance 28 at the gate terminal of the 2nd LEDcurrent control transistor 22A, connect the3rd resistance 29 at the gate terminal of the 3rd LED current control transistor 23A.These each LED current control transistors are controlled by the collector voltage of the current detecting transistor that makes up separately.

Moreover; Utilizing a LEDcurrent control transistor 21A, the 2nd LEDcurrent control transistor 22A; Be in the structure of switching of unit control ON/OFF with the LED piece; Because the control of the FET of the LED current control transistor that formation is at different levels etc. is connected to the two ends of LED piece with semiconductor element, so controls and protect with the withstand voltage total forward voltage by the LED piece of semiconductor element.Therefore, existence can be used the advantage of withstand voltage low small-sized semiconductor element.

(current detecting control unit)

The current detecting control unit is according to carrying out the parts that the mode of constant current driven is controlled with LED piece current corresponding control unit in appropriate timing.As the current detecting control unit, the also switch element of transistor capable of using etc.Particularly bipolar transistor is fit to be applied to the detection of the magnitude of current.In this example; The first current detecting control unit 31 is made up of the first current detectingtransistor 31A; The second current detectingcontrol unit 32 is made up of the second current detectingtransistor 32A, and the 3rd current detectingcontrol unit 33 is made up of the 3rd current detecting transistor 33A.Moreover the current detecting control unit also is not limited to bipolar transistor, also can be made up of MOSFET, comparator, operational amplifier, variable resistor etc. certainly.

In the example of Fig. 2, constitute the current detecting control unit by current detecting transistor.Each current detecting transistor is controlled the action of LED current control transistor respectively.That is, each current detecting transistor is in ON/ constant current control/OFF, thereby the LED current control transistor is switched to OFF/ constant current control/ON.

On the other hand, constitute the LEDcurrent sense resistor 4A of current detecting unit 4, be connected in the base terminal of each current detecting transistor via base resistance.Particularly; Base terminal at the first current detectingtransistor 31A connects first base resistance 41; Base terminal at the second current detectingtransistor 32A connectssecond base resistance 42; Base terminal at the 3rd current detectingtransistor 33A connects the3rd base resistance 43, and each base resistance is connected between each base terminal and the LEDcurrent sense resistor 4A.

In addition, between the base terminal and ground wire of the second current detectingtransistor 32A, connectsecond base bleederresistance 34, and then between the base terminal and ground wire of the 3rd current detectingtransistor 33A, connect the 3rd base bleederresistance 35.The action of these second, third current detecting transistors is that base resistance and base bleederresistance are set by base current.Moreover ground wire in this manual is not limited to what is called and is connected in the earth, also comprises imaginary earth point certainly.For example, the metallic casing of lighting device can be used as imaginary earth point.

The resistance value regulation of each base resistance, base bleederresistance and LEDcurrent sense resistor 4A is carried out the ON/OFF of each current detecting transistor according to the timing of which electric current.At this, be set to the mode of ON according to order with the first current detectingtransistor 31A, the second current detectingtransistor 32A, the 3rd current detectingtransistor 33A, set the resistance value of each base resistance and base bleederresistance.

(reference current value)

At this; Set first reference current value to such an extent that be lower than second reference current value; Wherein first reference current value is that the first current detectingtransistor 31A makes a LEDcurrent control transistor 21A switch to the reference current value of OFF from ON, and second reference current value is that the second current detectingtransistor 32A makes the 2nd LEDcurrent control transistor 22A switch to the reference current value of OFF from ON.In addition, the 3rd reference current value that makes the 3rd LEDcurrent control transistor 23A switch to OFF from ON the 3rd current detectingtransistor 33A is set to such an extent that be higher than second reference current value.Like this; Through being set at first reference current value＜second reference current value＜the 3rd reference current value; Can be as above-mentioned be the order of LED current-limitingresistance 3A according to aLED piece 11, the2nd LED piece 12, the3rd LED piece 13, current limliting unit 3; Switch to ON from OFF, and when ON switches to OFF reversed in order.

Moreover in this example, because each LED piece and current limliting unit 3 are connected in series, the magnitude of current that flows through them is consistent.Thus, be the energising amount of LEDcurrent sense resistor 4A based on the current detecting unit 4 that is connected in series with them, the ON/OFF that carries out LED current control transistor at different levels switches.

Have again, connect transistor load resistance respectively at the collector terminal of each current detecting transistor.Particularly; Collector terminal at the first current detectingtransistor 31A connects the firsttransistor load resistance 36; Connect transistor seconds loadresistance 37 at the collector terminal of the second current detectingtransistor 32A, connect the 3rdtransistor load resistance 38 at the collector terminal of the 3rd current detecting transistor 33A.According to the total forward voltage V that rises to aLED piece 11 at pulsating voltage_FB1Before neighbouring, each LEDcurrent control transistor 21A, 22A, 23A become the mode of ON, set thesetransistor load resistance 36,37,38 resistance value separately.

(action specification)

This light emittingdiode drive device 200 can be kept the power-efficient more than 90%; Improve LED utilization ratio and power factor simultaneously; Therefore and the circuit by with the semiconductor element being main body constitutes, and utilizes the device that can be implemented in excellence aspect small-sized, the thermal endurance environment under at LED.Below, with reference to the current waveform of Fig. 3, the current detecting control unit the when pulsating voltage of in the circuit example of Fig. 2, importing Figure 10 is described and the action of current control unit.Put on the input voltage ofLED piece group 1, carry out the pulsating voltage of rectification Figure 10 afterwards for the interchange that utilizes 2 pairs of source power supplies of rectification circuit.At this, study the action of 1 cycle portions.At first, rise to the total forward voltage V of aLED piece 11 from 0V at voltage_FB1During, stop electric currents by a LED piece 11.Therefore, as shown in Figure 3, produce the interval that does not have electric current to flow through.When using the LED element of 8 above-mentioned forward voltage 3.6V, owing to amount to forward voltage V_FB1Being 3.6 * 8=28.8V, is no power between 0V～28.8V at pulsating voltage therefore.

Next, rise to the total forward voltage V of aLED piece 11 when pulsating voltage_FB1When neighbouring; Because a LEDcurrent control transistor 21A, the 2nd LEDcurrent control transistor 22A, the 3rd LEDcurrent control transistor 23A in the circuit diagram of Fig. 2 all become ON, therefore the first bypass path BP1, the second bypass path BP2, the 3rd bypass path BP3 are all open-minded.Its result, electric current begins to flow through in the path of aLED piece 11 → LEDcurrent control transistor 21A → the 2nd LEDcurrent control transistor 22A → the 3rd LEDcurrent control transistor 23A → current sense resistor 40.Along with the rising of pulsating voltage, also increase owing to flow through the electric current of aLED piece 11, therefore such magnitude of current as shown in Figure 3 increases gradually.And then, be accompanied by the increase of the magnitude of current, also rise through the magnitude of current that the first bypass path BP1, the second bypass path BP2, the 3rd bypass path BP3 flow to LEDcurrent sense resistor 4A from aLED piece 11.

And then when the pulsating voltage rising reached the electric current of being set by LEDcurrent sense resistor 4A, the first current detectingtransistor 31A that is connected with base terminal through first base resistance 41 became ON, began energising.Along with the rising of pulsating voltage, the collector current of the first current detectingtransistor 31A increases gradually, and its voltage drop of the firsttransistor load resistance 36 as a result becomes big, and the collector voltage of first current detecting transistor descends.Therefore, the grid voltage of a LEDcurrent control transistor 21A descends, and switches to OFF from ON.Its result, the first bypass path BP1 is cut off, and begins to 12 energisings of the 2nd LED piece.At this moment, the firstcurrent control transistor 21A switches to the transfer of OFF from ON during, be the total forward voltage V that pulsating voltage reaches aLED piece 11 and the2nd LED piece 12_FB1+ V_FB2Before, the2nd LED piece 12 can not lighted, and aLED piece 11 is by constant current driven.Its result becomes the level of the I-1 among Fig. 3.

Under this state, when pulsating voltage continues the total forward voltage V that rising reaches aLED piece 11 and the2nd LED piece 12_FB1+ V_FB2The time, 12 beginnings of the 2nd LED piece are lighted, and such current value as shown in Figure 3 begins to rise once more.And electric current increases gradually, and the magnitude of current that flows through among the LEDcurrent sense resistor 4A also rises, and when its result reached the current value of being set bysecond base resistance 42 andsecond base bleederresistance 34, the second current detectingtransistor 32A began action.Like this, the collector current of the second current detectingtransistor 32A increases gradually, causes the voltage drop of transistor seconds loadresistance 37 to increase.Thus, the grid voltage of the 2nd LEDcurrent control transistor 22A descends, and switches to OFF from ON, and the second bypass path BP2 is cut off and begins to 13 energisings of the 3rd LED piece.At this moment, reach the total forward voltage V of aLED piece 11～the3rd LED piece 13 at pulsating voltage_FB1+ V_FB2+ V_FB3Before during, the3rd LED piece 13 is not lighted, the2nd LED piece 12 is by constant current driven.Its result becomes the level of the I-2 among Fig. 3.

Equally, also carrying out ON/OFF to the 3rd LED piece 13 switches and constant current driven.That is, reach the total forward voltage V of a LED piece 11～the 3rd LED piece 13 when pulsating voltage_FB1+ V_FB2+ V_FB3The time, the 3rd LED piece 13 begins to light, and such current value as shown in Figure 3 begins to rise once more.And the magnitude of current that flows through among the LED current sense resistor 4A rises, and when reaching the current value of being set by the 3rd base resistance 43 and the 3rd base bleederresistance 35, the 3rd current detecting transistor 33A begins action.And the collector current of the 3rd current detecting transistor 33A increases gradually, and the voltage drop of the 3rd transistor load resistance 38 increases.Thus, the grid voltage of the 3rd LED current control transistor 23A descends, and switches to OFF from ON, thereby the 3rd bypass path BP3 is cut off and begins to switch on to LED current-limiting resistance 3A.At this moment, reach the voltage V of a LED piece 11～LED current-limiting resistance 3A at pulsating voltage_FB1+ V_FB2+ V_FB3+ V_3ABefore, LED current-limiting resistance 3A is not energized, and the 3rd LED piece 13 is by constant current driven.Its result has realized the level of the I-3 among Fig. 3.

In addition, pulsating voltage become maximum voltage near, all LEDcurrent control transistor 21A, 22A, 23A become OFF fully, in all LED, flow through electric current through LED current-limitingresistance 3A and LED current sense resistor 4A.Thus, can effectively utilize near the electric power of maximum voltage.But, may not make it be in OFF,, also can in all LED, flow through electric current even if for example make LEDcurrent control transistor 23A keep the state of ON for final grade current control unit.In this case, make LEDcurrent control transistor 23A not be in OFF, also can partly implement constant current and control and limit current value with the peak value of input voltage.

Moreover when pulsating voltage reached maximum voltage 141V, magnitude of voltage changed minimizing into, expression and above-mentioned opposite pattern.Have again, after pulsating voltage reaches the OV as minimum voltage, be converted to rising once more, therefore above-mentioned repeatedly action.

Like this, the level of carrying out constant current driven can be freely set in the setting of the base bleederresistance through LEDcurrent sense resistor 4A and current detecting transistor.In addition, in the foregoing circuit example, do not use coil and big capacitors, can realize small-sized, cheap, light weight, high performance LED drive unit.And then, not using HF switch, this can expect to suppress the high order harmonic component noise.

In addition,, therefore can not rely on the individual difference of the characteristic deviation of each LED element, particularly Vf, carry out the correct control of lighting owing in above-mentioned method, carry out and the actual magnitude of current control corresponding that in LED piece etc., flows through.Have again,, can only constitute, also can obtain the advantage that suppresses cost lower by semiconductor element because therefore control itself can not need the control element of this high price of microcomputer with open-and-shut circuit structure realization.

In the measured value during according to the mode forming circuit constant that becomes LED current waveform shown in Figure 3; Power-efficient=90%, LED utilization ratio=50%, power factor are 98%, can confirm to have improved LED utilization ratio and power factor with respect to constant current circuit.

Moreover in said structure, the utilization ratio of 3 LED pieces is different.The power ratio that the LED piece that utilization ratio is the highest is made as each LED piece of 100 o'clock is a LED piece: the 2nd LED piece: the 3rd LED piece=100: 95: 74.But, even if it is poor between the LED piece, to produce illumination, neither be with the visual level that can clearly discern, through in the configuration of LED element, working hard, thereby can reach the level that influences can avoided, no problem in practical application.

In said structure, compare with circuit as Figure 14 of existing example, its advantage be to realize can with the Vf deviation of light-emitting diode and the corresponding action of temperature characterisitic deviation of Vf.That is, in the circuit example of Figure 14, switch lighting of each LED piece with input voltage.Therefore, need make the switched voltage value of lighting of switching the LED piece correctly consistent with the Vf value of the LED element that constitutes each LED piece.But, because there is individual difference in the LED element, in each interelement Vf and temperature characterisitic, have deviation, so to make switched voltage correctly consistent with the Vf of LED element in the reality be very difficult.

With respect to this, in the above-described embodiments, carry out the switching of each LED piece, rather than carry out based on voltage based on electric current.That is, each LED piece is carried out constant current control, change the current value of its switching simultaneously to each LED piece, thereby switch lighting of LED piece successively.In other words, with respect in Figure 14, the control of the constant current of each LED piece being set at identical current value, make the current value of constant current control of each LED piece different in the present embodiment.If this method, its result switches on to other LED BOB(beginning of block)s that make current bypass when carrying out constant current control with FET as the Vds voltage broadening of the FET of LED current control transistor.Like this, according to present embodiment,, therefore can provide and practical and useful circuit formation owing to can realize absorbing the action of the deviation of Vf and temperature characterisitic easily.

In addition, be constant with respect to the energising amount of LED piece in the circuit example of Figure 14, in said structure by different constant current control break current values.Thus, suppress the magnitude of current of long LED piece of the time of lighting, realize long lifetime.Particularly, make the time of the lighting constant current controlled quentity controlled variable of the long LED piece controlled quentity controlled variable minimum of promptly switching on, make the energising controlled quentity controlled variable of the 3rd the shortest LED piece of the time of lighting maximum.Its result because the current value when under the situation that the 3rd LED piece extinguishes, lighting a LED piece diminishes, therefore can also suppress its caloric value (current value * light the time).That is the deterioration of the LED piece in the time of, can suppressing to contrast with the 3rd LED piece.Same situation with the relation of the 2nd LED piece in also can realize.Like this; Do not make the magnitude of current of constant current control constant; But change according to the long more low more mode of LED piece of the time of lighting; The uneven homogenize of life-span (life) characteristic of light-emitting diode can be relaxed thus, the control of lighting of the stable light-emitting diode that uses can be implemented in the more long-term process.

In addition, as the circuit of Figure 14 example such when make current value constant power factor worsen, thereby but shown in Fig. 3 grade that kind approach can the be improved effect of power factor of input voltage waveform through making current waveform.

(embodiment 2)

Above action is the control of having considered power factor.Special in the circuit example of Fig. 2 owing to be the structure that LEDpiece group 1 is serially connected in single line, therefore through each LED piece is carried out constant current control with different current values respectively, thus shown in the curve of Fig. 3 that kind that current waveform is become is stepped.On the other hand, asembodiment 2, expression utilizes the example that the circuit of Fig. 2 carries out comparing with power factor the control of more paying attention to utilization ratio in the voltage waveform of Fig. 4.In this control example, compare with the example of Fig. 3, control approximating mode according to the constant current that makes each LED piece and set resistance value etc., improve output through increasing the whole magnitude of current, obtain brighter illumination light.As LED current waveform shown in Figure 4; Measured value during the forming circuit constant is power-efficient=90%, LED utilization ratio=53%, power factor 95%; Compare withembodiment 1,, can confirm to improve the LED utilization ratio although power factor has a little decline.Like this, identical even if circuit constitutes, through selecting circuit constant, can constitute lighting device corresponding to the requirement specification.

(embodiment 3)

In above example, making the LED current sense resistor is common in each LED piece etc.That is, each current detecting control unit is controlled based on the magnitude of current of common current detecting unit, can simplify circuit and constitute.But, also can adopt the structure that the LED current sense resistor is set separately respectively to each LED piece etc.As embodiment 3, the such example of expression in the circuit diagram of Fig. 5.In the light emitting diode drive device 300 shown in this figure, basic structure and action andembodiment 1 are roughly the same, to 3 LED pieces the LED current sense resistor are set respectively.Particularly, carry out the current detecting of the2nd LED piece 12, carry out the current detecting of the3rd LED piece 13, carry out the current detecting of LED current-limiting resistance 3B by the 3rd LEDcurrent sense resistor 4D by the 2nd LEDcurrent sense resistor 4C by a LED current sense resistor 4B.In addition, in this example,, do not use FET and be to use bipolar transistor, have again, make 2 bipolar transistors form the Darlington transistor that Darlingtons connect as the LED current control transistor that constitutes current control unit.

In the circuit of Fig. 5, can control according to the mode that makes its current waveform become Fig. 3 or Fig. 4.At this, use the circuit of Fig. 5 to control to make when becoming the example of the current waveform of Fig. 3 in explanation, the alternating voltage of source power supply is identical by the pulsating voltage this point that protective resistance 17, rectification circuit 2 carry out rectification and become Figure 10 with embodiment 1.Moreover, in the circuit example of Fig. 5, do not use by-pass capacitor.Rise to the total forward voltage V of a LED piece 11 from 0V at voltage_FB1During, stop electric currents by a LED piece 11, do not have electric current to flow through.When rising to, pulsating voltage amounts to forward voltage V_FB1When neighbouring; Because a LED current control transistor 21B, the 2nd LED current control transistor 22B, the 3rd LED current control transistor 23B in the circuit diagram of Fig. 5 all become ON; Therefore the first bypass path BP1, the second bypass path BP2, the 3rd bypass path BP3 all are switched on, and electric current begins to flow through according to the path of a LED piece 11 → LED current control transistor 21B → LED current sense resistor 4B → the 2nd LED current control transistor 22B → the 2nd LED current sense resistor 4C → the 3rd LED current control transistor 23B → the 3rd LED current sense resistor 4D.Along with the rising of pulsating voltage, the electric current that flows through a LED piece 11 increases, and the magnitude of current that flows through among the LED current sense resistor 4B also rises.

Have, when the pulsating voltage rising reached the electric current of being set by a LEDcurrent sense resistor 4B, the first current detectingtransistor 31B that is connected with base terminal through the first base resistance 41B became ON, began energising again.Along with the rising of pulsating voltage, the collector current of the first current detectingtransistor 31B increases gradually, and its result reduces from the base current that the firsttransistor load resistance 36B flow to the first current control transistor 21B, switches to OFF from ON.Its result first bypass path BP1 is cut off, and begins to 12 energisings of the 2nd LED piece.At this moment, reach the total forward voltage V of aLED piece 11 and the2nd LED piece 12 at pulsating voltage_FB1+ V_FB2Before, the2nd LED piece 12 is not lighted, and aLED piece 11 is by constant current driven.

Pulsating voltage rises under this state, as the total forward voltage V that reaches aLED piece 11 and2LED piece 12_FB1+ V_FB2The time, the2nd LED piece 12 begins to light.Have, the magnitude of current that flows through among the 2nd LEDcurrent sense resistor 4C also rises gradually again, and when its result reached the current value of being set by the second base resistance 42B, the second current detecting transistor 32B began action.And; The collector current of the second current detecting transistor 32B increases gradually; Its result reduces to the electric current of the 2nd LED current control transistor 22B side branch from transistor seconds loadresistance 37B, and the base current of the 2nd LED current control transistor 22B descends, and switches to OFF from ON; The second bypass path BP2 is cut off, thereby begins to 13 energisings of the 3rd LED piece.At this moment, reach the total forward voltage V of aLED piece 11～the3rd LED piece 13 at pulsating voltage_FB1+ V_FB2+ V_FB3Before, the3rd LED piece 13 is not lighted, and the2nd LED piece 12 is by constant current driven.

Equally, reach the total forward voltage V of aLED piece 11～the3rd LED piece 13 when pulsating voltage_FB1+ V_FB2+ V_FB3The time, the3rd LED piece 13 begins to light, and current value begins to rise once more.And the magnitude of current that flows through among the 3rd LEDcurrent sense resistor 4D rises, and when reaching the current value of being set by the 3rd base resistance 43B, the 3rd current detectingtransistor 33B begins action.Have again; The collector current of the 3rd current detectingtransistor 33B increases gradually; The electric current that flows to the 3rd LED current control transistor 23B from the 3rdtransistor load resistance 38B is to the 3rd current detectingtransistor 33B side branch, and the base current of the 3rd LED current control transistor 23B reduces, and switches to OFF from ON; The 3rd bypass path BP3 is cut off, thereby begins to switch on to LED current-limiting resistance 3B.

Pulsating voltage become maximum voltage near, all LED current control transistor 21B, 22B, 23B are in OFF fully, through the 3rd LEDcurrent sense resistor 4D, in all LED, flow through electric current.Thus, can effectively utilize near the power of maximum voltage.In addition, when pulsating voltage reached maximum voltage 141V, magnitude of voltage changed minimizing into, occurred and above-mentioned opposite action.

In this circuit example, can easily adjust the current value that makes each LED piece and 3 actions of current limliting unit separately by each LED current sense resistor.On the contrary, its shortcoming is, uses a plurality of LED current sense resistors, thereby is increased by the thermal losses that these resistance cause, and the LED piece is cut off into module.On the other hand, as advantage, for example having differently with Fig. 2 etc. does not have intersecting of wiring, becomes easy thereby do not need three-dimensional wiring circuit to constitute.Moreover; In above circuit; By firstcurrent control unit 21, the first current detecting control unit 31, the first current detectingunit 4B; Formation is switched first switch unit of the ON/OFF of the first bypass path BP1 based on the energising amount of aLED piece 11; In addition, constitute second switch unit that switches the ON/OFF of the second bypass path BP2 based on the energising amount of aLED piece 11 and the2nd LED piece 12 by secondcurrent control unit 22, the second current detectingcontrol unit 32, the second current detectingunit 4C.

In above embodiment 1～3, all be to switch to ON, and then switch to OFF according to order from the 3rd LED BOB(beginning of block) the 2nd LED piece, a LED piece according to order from a LED BOB(beginning of block) the 2nd LED piece, the 3rd LED piece.Therefore, each LED piece lights asynchronism(-nization).Like this, long the 3rd LED piece etc. becomes eye-catching during extinguish, and for the configuration of LED element, its dispersion is configured, rather than each LED piece becomes a pile.For example, after in the lighting device of Fig. 6 of stating, every row configuration belong to a LED piece the LED element, belong to the 2nd LED piece the LED element, belong to the 3rd LED piece LED element and then first, second, third,,, alternately dispose the LED element.Perhaps; Not with behavior unit; But be unit with the point, from upper left the right side configuration belong to a LED piece the LED element, belong to the 2nd LED piece the LED element, belong to the 3rd LED piece LED element and then first, second, third,,, the different LED element of LED piece under the next to the right ground configuration successively.In addition; Be not limited to dispose singly; Also can be per 2 or per more than 3 for unit, or be not periodic arrangement but structure arranged at random etc. suitably make the LED piece disperse to dispose the LED element, can make and light temporal differences and become not obvious.Thus, even if light repeatedly with the 60Hz cycle of source power supply, the user not can be appreciated that flicker yet, can light likewise continuously with the LED element and utilize.In addition,, accelerate ignition period, also can obtain same effect even if use inverter circuit etc. in addition.

Moreover in said structure, the service time of each LED element is different in each LED piece.Particularly, the time of lighting of a LED piece is the longest, and the time of lighting of the 3rd LED piece is the shortest.Therefore, can consider to suppress the deviation of the component life that causes because of usage frequency.In foregoing circuit constitutes, the connection because the LED piece is one another in series, so the voltage control of each LED piece is comparatively difficult.Therefore, for the high LED piece of usage frequency, increase the LED number of elements that is connected, not only being connected in series also is connected in parallel, and to reduce the magnitude of current of each element, suppresses thermal losses.

In addition, in said structure, LED piece number is set at 3, but as stated LED piece number also can be set at 2, or more than 4.For example, in the light emitting diode drive device of Fig. 1, also possess: the 4th LED piece that constitutes by a plurality of light-emitting diodes that between the 3rd LED piece and current limliting unit, is connected; Be used to limit the 4th current control unit with the current limliting unit is connected in parallel to the energising amount of a LED piece, the 2nd LED piece, the 3rd LED piece and the 4th LED piece; Be used to control the 4th current detecting control unit that is undertaken by the 4th current control unit to the energising limit amount of a LED piece, the 2nd LED piece, the 3rd LED piece and the 4th LED piece.At this, the 3rd current control unit replaces current limliting unit and the 4th LED piece to be connected in parallel.Thus, thus the quantity that increases the LED piece can be carried out the switching controls of lighting of more careful LED interblock, further improves the LED utilization ratio.In addition, LED piece number also can increase to more than 5, can carry out the more careful switching controls of lighting thus.

(embodiment 4)

With this LED piece number be 4 light emittingdiode drive device 400 as embodiment 4, its circuit diagram of expression among Fig. 6.Light emitting diode drive device and Fig. 1 etc. shown in this figure are different, and the4th LED piece 14 is set between the3rd LED piece 13 and current limliting unit 3.In addition, its result the 3rdcurrent control unit 23 replacement current limliting unit 3 and the4th LED piece 14 are connected in parallel.In addition, the 4th newcurrent control unit 15 that is connected in parallel in current limliting unit 3, and then at the 4thcurrent control unit 15 connections the 4th current detecting control unit 16.The restriction of the 4thcurrent control unit 15 is to the energising amount of aLED piece 11, the2nd LED piece 12, the3rd LED piece 13 and the 4th LED piece 14.In addition, 16 controls of the 4th current detecting control unit are by the energising limit amount of 15 pairs the one LED pieces of the 4thcurrent control unit 11, the 2nd LED piece, the3rd LED piece 13 and the 4th LED piece 14.Like this, through increasing LED piece number, increased the quantity of constant current control, thereby can carry out the switching controls of lighting of more careful LED interblock.

(embodiment 5)

Have, asembodiment 5, expression is the light emitting diode drive device of purpose in multi-level pmultistage circuit, to improve wave height rate (crestfactor) among Fig. 7 again.Exceptcapacitor 18, the light emittingdiode drive device 500 of Fig. 7 adopts the roughly the same structure of circuit example with Fig. 2, therefore, gives identical symbol for identical parts, and omits its detailed description.

Light emittingdiode drive device 500 shown in Figure 7 can be avoided all extinguishing this so-called stroboscopic (strobo) phenomenon at the low regional light-emitting diode of pulsating voltage.So-called stroboscopic phenomenon; Be meant pulsating voltage in AC driving be 0V near; Can put on the forward voltage step-down of LED element; Interval final even that extinguish occurs,, seem that moment is static, or seem the phenomenon that stops to will carry out throwing light on the time with this object that extinguishes the action of cycle synchronisation.For example; When the middle diel devices that move up and down that use such as workshop being thrown light on the LED lighting device that carries out AC driving; When the cycle of extinguishing that the cycle and the LED of the diel that moves up and down throw light on was synchronous once in a while, diel looked like and stops.In addition, except this situation, also exist and feel in the illumination that flicker can make eye fatigue, or the problem that seems to move artificially etc.

In addition, as the evaluation index of the numerical value property relevant, enumerate efferent echo high rate (wave height value) with stroboscopic phenomenon.The wave height rate defines according to (peak value of light beam) ÷ (effective value of light beam).It is stable more good value that this wave height rate approaches 1.0.Under the situation of moving with direct current, the wave height rate is 1.0, but under this periodically variable situation of the application the value of expression more than 1.According to the JIS specification, be defined as below 1.2 in the fluorescent lamp etc.In other words, the wave height rate approaches 1.0, then gives birth to stroboscopic phenomenon all the more, can be described as the high light source of versatility.In addition, in the reality, although the not special provision relevant with the LED lighting device thought if can withstand actual use 1.3 with next.When realizing above-mentioned current waveform shown in Figure 3 with multi-level pmultistage circuit, the wave height rate is 1.4～1.6.On the other hand, when making current waveform shown in Figure 4 be advanced into the border, judge and can the wave height rate be reduced to about 1.34.

Like this, also can tackle even wave height rate about 1.3, become in the wave height rate in the middle of the field, purposes of problem, can fully tackle by above-mentioned multi-level pmultistage circuit.

At this, in order to make the wave height rate, in Fig. 4, be also need light LED near theinterval 0 at electric current further near 1.0.But input voltage self can descend originally in this interval, can't sufficient voltage be provided to the LED element.Therefore, in the structure that sufficient voltage can be provided, need the change circuit, on this, need append the parts of other element etc., produced circuit and constituted complicated, power consumption increase, circuit maximizes and manufacturing cost improves problem.

Relative therewith, related light emittingdiode drive device 500 that kind as shown in Figure 7 ofembodiment 5 the outlet side ofrectification circuit 2 and ground wire between increased capacitor 18.,, therefore in this interval, also can supply power at the outlet side ofrectification circuit 2capacitor 18 that is connected in parallel through like this, it is lighted the LED element of aLED piece 11 owing to when voltage descends, can electric current be provided from capacitor 18.Its result because the LED element of aLED piece 11 is lighted all the time, therefore can avoid stroboscopic phenomenon.According to the experiment that the present inventor carries out, find that through inserting electrostatic capacitance be the electrolytic capacitor of 10 μ F, can the wave height rate be suppressed at about 1.2.Wherein, use the littler capacitor of electrostatic capacitance, also can the wave height rate be suppressed at 1.2 levels.

At general constant current circuit or only be that the electrostatic capacitance of the capacitor that uses in the circuit of resistance needs about 100～300 μ F.This big electric capacity only can be realized by electrolytic capacitor in reality, becomes larger-size capacitor.When larger-size capacitor being installed on the substrate identical with the LED element, capacitor might hinder the luminous intensity distribution from the LED element, and has significantly hindered the design of compact.In addition, electrolytic capacitor has certain life-span, and this life-span is much smaller with respect to the life-span of LED element, and therefore, electrolytic capacitor has determined life of product, has lost the original this advantage of long-life of LED element.

With respect to this,, therefore can constitute by the extremely long parts of life-span of film capacitor etc. because in this multi-level pmultistage circuit ofembodiment 5, electrostatic capacitance is just enough about 10 μ F.The reason that can reduce electrostatic capacitance like this is, according to original in multi-level pmultistage circuit during for lower input voltage, to make the part of LED coupled in series element group light that this conception constitutes.In other words, its reason is, because to a certain extent also can the driving LED element with lower voltage, so the voltage that can reduction need be kept by capacitor.

Like this, the light emittingdiode drive device 500 ofembodiment 5 relates to the LED lighting device of AC driving, can realize good wave height rate.In addition, its life of product is not by the capacitor decision, can realize the optimization of wave height rate.

(embodiment 6)

Have, Figure 19 representes the light emittingdiode drive device 600 that embodiment 6 is related again.Light emittingdiode drive device 600 shown in this figure possesses smoothingcircuit 50, and this smoothingcircuit 50 can not begin discharge before at the capacitor discharge ionization voltage that input voltage drops to regulation.For fear of general in the lower zone of pulsating voltage light-emitting diode all extinguish this so-called stroboscopic phenomenon, connect the smmothing capacitor that the input voltage after the full-wave rectification is carried out smoothing at the outlet side of rectification circuit 2.But, need the capacity of smmothing capacitor bigger.For example, when obtaining the light source of output 10W, adopt the capacitor of 9.4 μ F.When using electrolytic capacitor as jumbo capacitor, the durability aspect goes wrong.In addition, make electric capacity when work as smmothing capacitor 73 a plurality of film capacitors that are connected in parallel, have the problem of cost and space increase in that kind shown in figure 16.Therefore, in the circuit of embodiment shown in Figure 19 6, be employed in charge stored in the smmothing capacitor input voltage lower during this structure that begins to discharge.

Constitute to compare with circuit shown in Figure 16 above-mentioned action is described.Figure 17 represent in the circuit of Figure 16 by the input voltage waveform after the capacitor smoothing.As shown in the drawing, begin from the time point that surpasses peak value as the rectified waveform after the full-wave rectification of input voltage (dotted line), the discharge of smmothing capacitor begins naturally.Its result, such interdischarge interval is elongated shown in solid line, needs jumbo capacitor.In addition, also requirement can be withstood the high withstand voltage of crest voltage.For the LED piece of this multilevel hierarchy that makes Figure 16 is lighted all the time; Just for aLED piece 11 is extinguished; The minimum voltage that needs LED will be lighted, be that the minimum forward voltage of the minimum LED piece of forward voltage (belongs to aLED piece 11 in the circuit example of Figure 16; Be set to 80V) maintain the voltage more than the 80V by smmothingcapacitor 73, make can not be lower than input voltage.Thus, the beam shape of lighting generation by the LED piece becomes Figure 18 that kind (power consumption 9.5W, light beam 768lm, wave height rate 1.17, power factor 58%).

With respect to this, increase smoothing circuit 50 shown in Figure 19 through outlet side at rectification circuit 2, can the capacity of smoothing capacitor be suppressed lower.Smoothing circuit 50 possesses smoothing capacitor 51, being used for the charge path of its charging and the discharge path that is used to discharge of being connected with smoothing capacitor 51.Resistance 52 and discharge that charge path is inserted by series connection between rectification circuit 2, this rectification circuit 2 and smoothing capacitor 51 (+side) stop diode 53 to constitute.In addition; Discharge path is made up of with transistor 54 (example at Figure 19 is a bipolar transistor) with diode 56, bypass with transistor 55 (in the example of Figure 19, being FET) and discharge discharge; Discharge with transistor 55 with discharge with diode 56 with respect to tie point CP; Stop diode 53 to be connected in parallel with above-mentioned resistance 52 and discharge; Bypass, is connected in parallel with smoothing capacitor 51 with respect to the tie point CP between smoothing capacitor 51 and last note resistance 52 and the discharge prevention diode 53 with transistor 54.This bypass is with the action of transistor 54 control discharges with transistor 55.For example, when input voltage surpassed 80V, bypass was in ON with transistor 54, and discharge is in OFF with transistor 55.On the other hand, when input voltage is 80V when following, bypass is in OFF with transistor 54, and discharge is in ON with transistor 55, thereby begins to discharge.In addition, bypass is connected in the input voltage side with the base terminal of transistor 54 via Zener diode and resistance.When input voltage surpasses 80V and when reaching puncture voltage, this Zener diode flows through reverse current, promptly flow through base current in transistor 54 in bypass, make bypass be in ON with transistor 54.

Figure 20 representes to use the situation of smoothing of the input voltage of this smoothing circuit 50.As shown in the drawing, to crest voltage, stopdiode 53 to smoothingcapacitor 51 chargings from the lower state of input voltage throughresistance 52 and the discharge that constitutes charge path.Thisresistance 52 be used for when power connection relaxing smoothingcapacitor 51 flow through sharp electric current, impulse current relaxes resistance.

Begin to descend even if input voltage surpasses near the crest voltage, smoothingcapacitor 51 also can be stopeddiode 53 to stop discharge by discharge, becomes ON in discharge withtransistor 55 and can not discharge before.And; When reaching the capacitor discharge ionization voltage of regulation when further decline of input voltage; If discharge is in ON withtransistor 55, then, begin the discharge of smoothingcapacitor 51 through by the discharge path that discharges and constitute withdiode 56 withtransistor 55 and discharge.During discharge, input voltage rises once more, until the forward voltage (minimum forward voltage) that surpasses the minimum LED piece of forward voltage.Thus, any LED piece (being aLED piece 11 in the circuit example of Figure 19) is lighted, can be suppressed stroboscopic phenomenon.

Through this smoothingcircuit 50, can make the capacitor discharge ionization voltage be lower than the peak value (141V) of the input voltage of Figure 16, therefore, can as Figure 17 and shown in Figure 20 shorten interdischarge interval.In addition; Shorten interdischarge interval and help to reduce required electrostatic capacitance, therefore can cut down the capacity of smoothing capacitor, can use the little capacitors of capacity such as film capacitor; Thereby and can cut down required number and reduce the space that capacitor occupies, help the miniaturization of device.

The capacitor discharge ionization voltage sets identically with minimum forward voltage, or be higher than this voltage.Thus, constitute eliminate that the LED piece extinguishes during, have any one LED piece to light all the time, thereby can reduce stroboscopic phenomenon.In the circuit example of Figure 19; Set the capacitor discharge ionization voltage; Make that kind shown in figure 20, the timing that smmothing capacitor begins to discharge are not and then after the crest voltage, but input voltage is lower than the time point of the required voltage of lighting of a LED piece (80V).In addition, the beam shape of the LED that obtains thus becomes Figure 21 that kind, even if produced the zone (part among Figure 21, between the trough) that a part of voltage is lower than 80V, but owing to is can confirm between utmost point short-term aspect visual identity, to eliminate stroboscopic phenomenon.Have again, obtained power consumption 9.5W (LED power 8W), power-efficient 84%, power factor 82%, average light beam 745lm, luminous efficiency 78lm/W, LED utilance 55%, wave height rate 1.23, with the light beam of the roughly the same degree of Figure 16.Have again, although the wave height rate a little less than the example of Figure 16, the capacity of required smmothing capacitor can be realized by Figure 16 half during circuit constituted, in manufacturing cost, aspect such as space is set has superiority.

(lighting device)

Since more than this light emitting diode drive device possess the LED element, through with LED element and drive circuitry arrangement thereof at same circuit board, thereby can make its lighting device of lighting or ligthing paraphernalia as inserting home-use AC power.

More than; Various execution modes of the present invention are illustrated; But the present invention is not limited to specific implementations disclosed herein; These execution modes are only used for explaining the simple illustration of technological thought of the present invention, should be understood to scope of the present invention to those skilled in the art and are not limited thereto, and can in the invention scope of the claim defined that adds, carry out various changes.

Utilizability on the industry

The lighting control method of light emitting diode drive device of the present invention and light-emitting diode can suitably be applied to lighting device, light-emitting diode display, laser writer etc.The present invention is particularly suitable for the driving of power LED and semiconductor laser.

Symbol description:

100,200,300,400,500,600 ... Light emitting diode drive device

1 ... LED piece group

2 ... Rectification circuit

3 ... The current limliting unit

3A, 3B ... The LED current-limiting resistance

4 ... Current detecting unit

4A ... The LED current sense resistor

4B ... The one LED current sense resistor

4C ... The 2nd LED current sense resistor

4D ... The 3rd LED current sense resistor

11 ... The one LED piece

12 ... The 2nd LED piece

13 ... The 3rd LED piece

14 ... The 4th LED piece

15 ... The 4th current control unit

16 ... The 4th current detecting control unit

17 ... Protective resistance

18 ... Capacitor

19 ... By-pass capacitor

21 ... First current control unit

21A, 21B, 21C ... The one LED current control transistor

22 ... Second current control unit

22A, 22B, 22C ... The 2nd LED current control transistor

23 ... The 3rd current control unit

23A, 23B, 23C ... The 3rd LED current control transistor

24 ... First grid protection Zener diode

25 ... Second grid protection Zener diode

26 ... The 3rd gate protection Zener diode

27 ... First grid resistance

28 ... Second grid resistance

29 ... The 3rd resistance

31 ... The first current detecting control unit

31A, 31B ... First current detecting transistor

32 ... The second current detecting control unit

32A, 32B ... Second current detecting transistor

33 ... The 3rd current detecting control unit

33A, 33B ... The 3rd current detecting transistor

34 ... Second base bleederresistance

35 ... The 3rd base bleederresistance

36,36B ... The first transistor load resistance

37,37B ... The transistor seconds load resistance

38,38B ... The 3rd transistor load resistance

41,41B ... First base resistance

42,42B ... Second base resistance

43,43B ... The 3rd base resistance

50 ... The smoothing circuit

51 ... Smoothing capacitor

52 ... Resistance

53 ... Discharge stops diode

54 ... Transistor is used in bypass

55 ... Transistor is used in discharge

56 ... Diode is used in discharge

61,62,63,64,65,66 ... The LED piece

67 ... The switch control part

71 ... AC power

72 ... Bridge circuit

73 ... Smmothing capacitor

74 ... Drive circuit

75 ... The LED group

81 ... AC power

82 ... Bridge circuit

84 ... Constant current circuit

85 ... The LED group

86 ... Feedback resistance

87 ... Current detecting transistor

88 ... Current control transistor

89 ... Current sense resistor

91,92,93 ... The LED piece

94 ... Zener diode

95 ... Resistance

AP ... AC power

BP1 ... First bypass path

BP2 ... Second bypass path

BP3 ... The 3rd bypass path

Claims (9)

1. light emitting diode drive device, it possesses:

Rectification circuit (2), it can be connected with AC power, and the alternating voltage that is used to obtain this AC power carries out rectification pulsating voltage afterwards;

A LED piece (11) that is connected in series successively with the outlet side of said rectification circuit (2), constitute by a plurality of light-emitting diodes, the 2nd LED piece (12) that constitutes by a plurality of light-emitting diodes and the 3rd LED piece (13) that constitutes by a plurality of light-emitting diodes;

First switch unit, it is based on the energising amount of a said LED piece (11), switches to make said the 2nd LED piece (12) become the ON/OFF of first bypass path (BP1) of bypass; With

Second switch unit, it is based on the energising amount of a said LED piece (11) and said the 2nd LED piece (12), switches to make said the 3rd LED piece (13) become the ON/OFF of second bypass path (BP2) of bypass.

2. light emitting diode drive device according to claim 1 is characterized in that,

Said first switch unit has:

First current control unit (21), itself and said the 2nd LED piece (12) are connected in parallel, and are used for the energising amount of restriction to a said LED piece (11);

The first current detecting control unit (31), it is used for control by the energising limit amount of said first current control unit (21) to a said LED piece (11); With

First current detecting unit (4B), itself and a said LED piece (11) are connected in series, and detect the energising amount of a said LED piece (11),

Said second switch unit has:

Second current control unit (22), itself and said the 3rd LED piece (13) are connected in parallel, and are used for the energising amount of restriction to a said LED piece (11) and said the 2nd LED piece (12);

The second current detecting control unit (32), it is used for control by the energising limit amount of said second current control unit (22) to a said LED piece (11) and the 2nd LED piece (12); With

Second current detecting unit (4C), itself and said the 2nd LED piece (12) are connected in series, and detect the energising amount of said the 2nd LED piece (12).

3. light emitting diode drive device according to claim 2 is characterized in that,

Make said first current detecting unit (4B) and second current detecting unit (4C) shared.

4. light emitting diode drive device, it possesses:

Rectification circuit (2), it can be connected with AC power, and the alternating voltage that is used to obtain this AC power carries out rectification pulsating voltage afterwards;

The one LED piece (11), it is made up of a plurality of light-emitting diodes that the outlet side with said rectification circuit (2) is connected in series;

The 2nd LED piece (12), it is made up of a plurality of light-emitting diodes that are connected in series with a said LED piece (11);

The 3rd LED piece (13), it is made up of a plurality of light-emitting diodes that are connected in series with said the 2nd LED piece (12);

Current limliting unit (3), itself and said the 3rd LED piece (13) are connected in series;

First current control unit (21), itself and said the 2nd LED piece (12) are connected in parallel, and are used for the energising amount of restriction to a said LED piece (11);

Second current control unit (22), itself and said the 3rd LED piece (13) are connected in parallel, and are used for the energising amount of restriction to a said LED piece (11) and said the 2nd LED piece (12);

The 3rd current control unit (23), itself and said current limliting unit (3) are connected in parallel, and are used for the energising amount of restriction to a said LED piece (11), the 2nd LED piece (12) and said the 3rd LED piece (13);

The first current detecting control unit (31), it is used for control by the energising limit amount of said first current control unit (21) to a said LED piece (11);

The second current detecting control unit (32), it is used for control by the energising limit amount of said second current control unit (22) to a said LED piece (11) and the 2nd LED piece (12); With

The 3rd current detecting control unit (33), it is used for control by the energising limit amount of said the 3rd current control unit (23) to a said LED piece (11), the 2nd LED piece (12) and the 3rd LED piece (13).

5. light emitting diode drive device according to claim 4 is characterized in that,

By the energising limit amount of said first current control unit (21) to a said LED piece (11), less than by the energising limit amount of said second current control unit (22) to a said LED piece (11) and the 2nd LED piece (12),

By the energising limit amount of said second current control unit (22), less than by the energising limit amount of said the 3rd current control unit (23) to a said LED piece (11), the 2nd LED piece (12) and the 3rd LED piece (13) to a said LED piece (11) and the 2nd LED piece (12).

6. according to claim 4 or 5 described light emitting diode drive devices, it is characterized in that,

Said light emitting diode drive device also possesses the current detecting unit (4) that between said current limliting unit (3) and ground wire, is connected,

The said first current detecting control unit (31), the second current detecting control unit (32), the 3rd current detecting control unit (33) limit the energising amount to a said LED piece (11), the 2nd LED piece (12), the 3rd LED piece (13) respectively based on the energising amount of said current detecting unit (4).

7. according to each described light emitting diode drive device of claim 1 to 6, it is characterized in that,

Said light emitting diode drive device also possesses the capacitor that between the outlet side of said rectification circuit (2) and ground wire, is connected.

8. the lighting control method of a light-emitting diode, it comprises the steps:

Acquisition is carried out rectification pulsating voltage afterwards to AC power;

This pulsating voltage is put on a LED piece (11), the 2nd LED piece (12) and the 3rd LED piece (13) that is connected in series each other, a plurality of light-emitting diodes are one another in series and connect;

Can switch with said the 2nd LED piece (12) thereby be connected in parallel makes the 2nd LED piece (12) become first current control unit (21) of ON/OFF of first bypass path (BP1) of bypass; Energising amount based on a said LED piece (11); In this energising amount is that setting switches to ON with first bypass path (BP1) when following, when this energising amount surpasses setting, first bypass path (BP1) is switched to OFF; And

At said first bypass path (BP1) thus switched under the state that said the 2nd LED piece (12) of OFF is energized; Can switch with said the 3rd LED piece (13) thereby be connected in parallel makes the 3rd LED piece (13) become second current control unit (22) of ON/OFF of second bypass path (BP2) of bypass; Energising amount based on said the 2nd LED piece (12); In this energising amount is that setting switches to ON with second bypass path (BP2) when following, when this energising amount surpasses setting, second bypass path (BP2) is switched to OFF.

9. the lighting control method of light-emitting diode according to claim 8 also possesses following steps:

At said second bypass path (BP2) thus switched under the state that said the 3rd LED piece (13) of OFF is energized; Can switch with being connected in series in the current limliting unit (3) of said the 3rd LED piece (13) thereby being connected in parallel makes this current limliting unit (3) become the 3rd current control unit (23) of ON/OFF of the 3rd bypass path (BP3) of bypass; Energising amount based on said the 3rd LED piece (13); In this energising amount is that setting switches to ON with the 3rd bypass path (BP3) when following, when this energising amount surpasses setting, the 3rd bypass path (BP3) is switched to OFF.

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