CN1305352C - Charging IC for camera flash - Google Patents

Abstract

A charging integrated circuit of a camera flash lamp comprises: a first single-click circuit which provides a square wave signal; the R-S latch is connected to the single click circuit; the pulse width regulation control circuit mainly comprises a reference voltage source, an oscillator, a pulse width regulation comparator, a boosting comparator and a current source; the ready control unit is mainly composed of a field effect transistor, and the gate of the field effect transistor is connected with the output end of the R-S latch; the circuit integration is used for realizing the charging control of the flash lamp, the volume is small, the integration is easy, and the flash lamp charging control circuit has the advantages of controlling the charging current, accelerating the charging speed, automatically recharging and the like.

Description

The charging integrated circuit of camera flash-light

Technical field

The present invention relates to photoflash lamp, more detailed it, be the charging integrated circuit that refers to a kind of camera flash-light.

Background technology

Known camera flash-light charging circuit is normally combined by a plurality of dispersion electronic components (for example electric capacity, transistor, resistance or the like), and not only overall volume is bigger, also more consuming time during assembling, consumption cost.Known in addition camera flash-light charging circuit all has immediate current excessive, the shortcoming that the stand-by period is of a specified duration excessively, and charging current belongs to big electric current, easily causes battery to damage.

Summary of the invention

Main purpose of the present invention is promptly providing a kind of charging integrated circuit of camera flash-light, and its immediate current is less, and can reach ready state fast, and the stand-by period is shorter.

Of the present invention time a purpose is the charging integrated circuit that is to provide a kind of camera flash-light, and electric current is controlled in its charging process, more can not damage battery.

A further object of the present invention provides a kind of charging integrated circuit of camera flash-light, and the volume of its integrated circuit is littler than known circuits, has better product applicability.

For achieving the above object, the invention provides a kind of charging integrated circuit of camera flash-light, include:

First one shots is a circuit and square-wave, and square-wave signal is provided;

The R-S latch, have one and set end (set), reset end (reset) and at least one output, this setting end is electrically connected at this first one shots, and the output voltage values of this output can be subjected to the signal controlling of this setting end and this replacement end and remain in a kind of output state;

Pulse width modulation control (PWM control) circuit, mainly by a reference voltage source, an oscillator, a pulse width modulation (PWM) comparator, boost comparator and a current source are formed, wherein, this reference voltage source provides reference voltage, this oscillator is connected in the first input end of this pulse width modulation comparator, a reference voltage partial pressure unit is connected in second input of this pulse width modulation comparator, the output of this R-S latch is connected in the 3rd input of this pulse width modulation comparator by an inverter and field-effect transistor, and this current source also is connected in the 3rd input; The output of this comparator that boosts is connected in the replacement end of this R-S latch;

Ready control unit mainly is made of a field-effect transistor, and the gate of this field-effect transistor is connected in the output of this R-S latch.

The charging integrated circuit of described camera flash-light, wherein more include: one is filled (refresh) circuit again, have a partial pressure unit and be connected in this reference voltage source, the output of this partial pressure unit is less than reference voltage, be connected in second one shots by a comparator, this second one shots is connected in the setting end of this R-S latch.

Via above-mentioned structure, can know and understand advantage of the present invention:

One, the charging interval is short: allow pwm pulse open charging at the very start when charging, save from starting to the time of delay that begins to charge, can reach ready state in the short time at the utmost point, can use photoflash lamp in the very short time interval.

Two, charging current is controlled, more can not damage battery: utilize the characteristic of pwm control circuit, electric current can effectively be avoided damaging battery, and then prolonged the life-span of battery by little and greatly to capacitor of flash lamp charging, avoid the instantaneous large-current phenomenon.

Three, volume is less: the present invention is integrated in the element that majority disperses in the integrated transistor, can effectively reduce the integrated circuit volume, has better product applicability.

Four, provide and recharge the road, the convenient use: utilize the circuit detecting because of capacity fall off produces the phenomenon of undertension, recharge automatically, increase the convenience that uses to the voltage of setting.

Description of drawings

Fig. 1 is the circuit structure diagram of a preferred embodiment of the present invention;

Fig. 2 is the operating principle key diagram of a preferred embodiment of the present invention.

Embodiment

Relevant detailed structure of the present invention, feature and effect below are lifted a preferred embodiment now, and cooperate diagram to be further described, wherein:

See also Fig. 1, the charging integratedcircuit 10 of a kind of camera flash-light that a preferred embodiment of the present invention provided, can be used to cooperate and be implemented on the camera (not shown), this charging integratedcircuit 10 mainly is made up of first oneshots 11,R-S latch 21, pulse width modulation control (PWM control)circuit 31 and aready control unit 41, wherein:

This first oneshots 11 is circuit and square-wave, and square-wave signal is provided;

ThisR-S latch 21, have a setting (Set) 22, replacements of end (Reset) end 24 and at least one output Q26, this setting end 22 is electrically connected at this first oneshots 11, and the output voltage values of this output Q26 can be subjected to the signal controlling of this setting end 22 and this replacement end 24 and remain in a kind of output state;

This pulse widthmodulation control circuit 31 mainly is made up of areference voltage source 32,oscillator 34, PWM (pulse width modulation)comparator 36,boost comparator 38 and a current source 39.Wherein:

Thisreference voltage source 32 is in order to provide reference voltage;

Thisoscillator 34 is connected in the first input end (-) of thisPWM comparator 36, a reference voltage partial pressure unit is connected in second input (+) of thisPWM comparator 36, adjustable settings PWM maximum pulse, the output of thisR-S latch 21 is connected in the 3rd input (+) of thisPWM comparator 36 by aninverter 361 and field-effect transistor 362, the 3rd input also is connected in an external SS end, can be for cooperating an external electric capacity (not shown), to determine whether this pulse widthmodulation control circuit 31 starts, reach the speed that pulse is changed from small to big;

Thiscurrent source 39 also is connected in the 3rd input (+) of thisPWM comparator 36;

This output that boostscomparator 38 is connected in the replacement end 24 of thisR-S latch 21;

Thisready control unit 41, being mainly a field-effect transistor constitutes. and the gate of this field-effect transistor (gate) is connected in the output of thisR-S latch 21, drain (drain) is to be output, can be for the ready signal light (not shown) that is connected on the camera (not shown);

The present invention more includes:

Fill (refresh)circuit 51 again, have apartial pressure unit 52 and be connected inreference voltage source 32, the output of thispartial pressure unit 52 be about thisreference voltage source 32 magnitude ofvoltage 90%, promptly less than reference voltage in a predetermined value.Be connected in second oneshots 56 by acomparator 54, this second oneshots 56 is connected in the setting end 22 of thisR-S latch 21;

By the combination of foregoing circuit, can provide the charging circuit for flashlamp that a volume is less, charging rate is fast.

Please consult Fig. 1 again, the present invention is when using, can be with the installation of on the camera, when the user judge or the extraneous light of the photosensitive elements sense of camera own after think and need to use photoflash lamp and charging circuit is opened, then this first oneshots 11 is promptly received the signal that is changeed high signal (high) by low signal (low), and the square wave that sends proper width makesR-S latch 21 enter set condition, the output Q26 of thisR-S latch 21 promptly sends the signal of high signal (high) and starts this pulse widthmodulation control circuit 31, and the output of thisready control unit 41 is low signal (low), when if this output is connected in preparation (ready) signal light, then preparing (ready) signal light can be not shinny;

As shown in Figure 2, when this pulse widthmodulation control circuit 31 begins to move, to be external in the trough of SS end pwm control circuit electric capacity (not shown) current potential quick charge relatively at the beginning earlier to theseoscillator 34 output triangular waves, after arriving trough, switching to this current source (1uA) 39 charges, pwm pulse is opened, beginning is extremely charged to capacitor of flash lamp greatly by little, so can output promptly be arranged at pulse widthmodulation control circuit 31 at the beginning, the electric capacity of photoflash lamp promptly begins charging, can reduce the whole time of capacitor of flash lamp charging like this; Voltage in the capacitor of flash lamp and reference voltage can be compared by thiscomparator 38 that boosts and to learn and be charged to predetermined voltage whether, after reaching predetermined voltage, thiscomparator 38 that boosts is promptly exported high signal (high), thisR-S latch 21 is promptly reseted (reset), this output Q26 promptly exports low signal (low), this pulse widthmodulation control circuit 31 promptly cuts out, and the output of thisready control unit 41 is high signal (high), has so far finished the program of charging.

If all be not activated photoflash lamp always, the then electric leakage (leakagecurrent) that capacitor of flash lamp can be slowly, voltage promptly can slowly descend, in case reduce to predetermined voltage (for example 90%), then thiscomparator 54 that rechargesroad 51 can be judged undertension and export high signal (high) with thisreference voltage source 32 by thispartial pressure unit 52, this second oneshots 56 promptly sends the square wave of proper width and makes thisR-S latch 21 enter set condition, and and then starts this pulse widthmodulation control circuit 31 and charge.

Start photoflash lamp after finishing charging, then capacitor of flash lamp is a sudden discharge, and capacitance voltage is promptly much smaller than predetermined voltage, and then this pulse widthmodulation control circuit 31 promptly can start once more, enters charge mode, and repeats aforementioned process.

Claims (2)

Translated fromChinese

1、一种相机闪光灯的充电集成电路，其特征在于，包含有：1. A charging integrated circuit for a camera flash, characterized in that it includes:第一单击电路，是一方波电路，提供方波信号；The first click circuit is a square wave circuit that provides a square wave signal;R-S锁存器，具有一个设定端、一个重置端以及至少一个输出端，该设定端电性连接于该第一单击电路，该输出端的输出电压值可受该设定端以及该重置端的信号控制而保持于一种输出状态；The R-S latch has a setting terminal, a reset terminal and at least one output terminal, the setting terminal is electrically connected to the first click circuit, the output voltage value of the output terminal can be controlled by the setting terminal and the The signal at the reset terminal is controlled to maintain an output state;脉冲宽度调节控制电路，主要由一个参考电压源、一个振荡器、一个脉冲宽度调节比较器、一个升压比较器以及一个电流源所组成，其中，该参考电压源提供参考电压，该振荡器连接于该脉冲宽度调节比较器的第一输入端，一个参考电压分压单元连接于该脉冲宽度调节比较器的第二输入端，该R-S锁存器的输出端由一个反相器以及一个场效应晶体管连接于该脉冲宽度调节比较器的第三输入端，该电流源亦连接于该第三输入端；该升压比较器的输出端连接于该R-S锁存器的重置端；The pulse width adjustment control circuit is mainly composed of a reference voltage source, an oscillator, a pulse width adjustment comparator, a boost comparator and a current source, wherein the reference voltage source provides a reference voltage, and the oscillator is connected to At the first input end of the pulse width adjustment comparator, a reference voltage divider unit is connected to the second input end of the pulse width adjustment comparator, and the output end of the R-S latch is composed of an inverter and a field effect The transistor is connected to the third input terminal of the pulse width adjustment comparator, and the current source is also connected to the third input terminal; the output terminal of the boost comparator is connected to the reset terminal of the R-S latch;就绪控制单元，主要由一个场效应晶体管所构成，该场效应晶体管的闸极连接于该R-S锁存器的输出端。The ready control unit is mainly composed of a field effect transistor, and the gate of the field effect transistor is connected to the output terminal of the R-S latch.2、根据权利要求1所述的相机闪光灯的充电集成电路，其特征在于：其中更包含有：一个再充电路，具有一个分压单元连接于该参考电压源，该分压单元的输出小于参考电压，由一个比较器连接于第二单击电路，该单击电路连接于该R-S锁存器的设定端。2. The charging integrated circuit for camera flash according to claim 1, further comprising: a recharging circuit having a voltage dividing unit connected to the reference voltage source, the output of the voltage dividing unit being smaller than the reference voltage source The voltage is connected to the second click circuit by a comparator, and the click circuit is connected to the setting end of the R-S latch.

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