CN1901768A - Method for controlling LED brightness - Google Patents

Abstract

This invention discloses a method for controlling brightness of LED, which utilizes a thyristor to control the 'on or off' state of the LED by zero-cross turning off and drives the turning-on of the LED by CPU emitting trigger pulses, in which, the thyristor makes the LED at the bright state for a part of time in a period of pulse supply or AC supply and dark state for the rest time and said CPU emits trigger pulses timely to control the turning-on time of the LED at the bright state. Advantage: simple structure and low cost.

Description

A kind of method of controlling LED brightness

Affiliated technical field

The present invention relates to a kind of illumination control circuit field, especially a kind of method of controlling LED brightness.

Background technology

The method of control LED brightness mainly contains at present: a kind of is electric current control method, and the electric current that flows through among the LED by change changes brightness.Each pixel all needs a controllable current source in this method, and its shortcoming is the circuit complexity, the cost height; Another kind is that PWM is the pulse-width modulation method, as China Patent No. be: 200510063068.5, name is called: " a kind of method of utilizing duty ratio control light-emitting diode luminance ", this technology is to control light-emitting diode is in " bright " state in the one-period of control signal time shared ratio in the described cycle by CPU or software approach, and utilize the persistence of vision of human eye, change brightness.Though the present invention can provide the brightness of required a plurality of grades for single light-emitting diode, but its weak point is: owing to utilize rectangular pulse to come the driven for emitting lights diode, add a high level that light-emitting diode is opened sometime in the one-period in control signal, then brightness moment of light-emitting diode reaches the brightest; To low level, the brightness amplitude of variation of its light-emitting diode is bigger to extinguishing from the brightest again in brightness, therefore makes that the brightness effect of light-emitting diode is poor, is difficult to realize required dreamlike effect at high level.

Summary of the invention

To the objective of the invention is in order addressing the above problem, to provide that a kind of circuit structure is simple, cost is low, good dimming effect can realize the method for a kind of LED of control brightness of fantasy effect.

To achieve these goals, the invention provides a kind of method of the LED of control brightness, it is characterized in that: utilize controllable silicon to control " bright " and " going out " state of LED by zero-crossing switching, and send the unlatching that trigger impulse comes driving LED by CPU, wherein, described controllable silicon makes the part-time of LED in the one-period of the pulse power or AC power be in " bright " state and be in " going out " state in all the other times, and the trigger impulse that described CPU sends in good time is used to control the opening time that LED is in bright state.

Described controllable silicon is an one-way SCR.

Described CPU is a singlechip chip EM78P153SN.

The present invention compared with prior art its beneficial effect is: light on and off and the opening time of controlling LED because of the trigger impulse that utilizes controllable silicon to send by zero-crossing switching and control chip in good time, and adopt storage chip and zero cross detection circuit that the brightness of LED is followed the trail of, the effect that simultaneously also can adopt the cheap LED of price just can reach to use in the conventional method LED of costliness just can reach, thereby solved circuit complexity in the conventional art, the problem that cost is high; Again because of give a pulse high level that LED is opened when the initial moment in the one-period of the pulse power, then the brightness of LED reaches the brightest, when in one-period near giving a pulse high level that LED is opened zero point constantly, then the brightness of LED is the most weak, at last utilize controllable silicon to automatically shut down constantly at the zero point of the pulse power, along with LED open-interval in one-period is postponed, then LED by the brightest to the most weak, extinguish at last, the overall process of control is exactly by between one-period and another cycle or regulate the light of LED, the brightness of LED therebetween changes comparatively mild, light is comparatively soft, thereby reach good dimming effect, be easy to produce dreamscape, realize dreamlike effect.

Description of drawings

Fig. 1 controls the control signal waveform schematic diagram of LED brightness for the present invention;

Fig. 2 is circuit theory diagrams of the present invention.

Embodiment

Below in conjunction with accompanying drawing, the present invention is further illustrated:

See figures.1.and.2, the present invention is a kind of method of the LED of control brightness, utilizecontrollable silicon 14 to control " bright " and " going out " state of LED by zero-crossing switching, and send the unlatching thattrigger impulse level 24 comes driving LED by CPU, CPU among this embodiment is a singlechip chip EM78P153SN, wherein, controllable silicon makes LED part-time of (0-t1) in the one-period of thepulse power 23 or AC power be in " bright " state and be in " going out " state in all the other times, preferred pulse power supply among this embodiment, and the trigger impulse that CPU sends in good time is used to control the opening time that LED is in bright state, owing to adopt the pulse power to come lighting of driving LED, its power supply signal changes comparatively mild, the light that LED sends is soft, and the brightness of adopting this kind method to regulate LED can produce fantasy effect.

Fig. 2 is the circuit connecting method that the present invention controls LED brightness, comprise city's power supply transformer, bridge rectifier, driving load, main control chip, storage chip and zero cross detection circuit, insert city'spower supply 21, alternating current is connected with the input ofbridge rectifier 3 behindfuse 20, city's power supply transformer 1 output voltageterminal filter capacitor 2 in parallel, constitutes to drive the required DC power supply of led light source in theload 4; Again with LED be connected in DC power supply aftercontrollable silicon 14 andresistance 12 are connected, wherein controllable silicon is an one-way SCR; Then silicon controlled being controlled the utmost point is connected with the collector electrode oftransistor 13, and be connected on the main control chip 6 behind theresistance 11 of connecting, this main control chip is a singlechip chip EM78P153SN, that is to say, this is located, and said CPU is identical among said main control chip and Fig. 1; DC power supply constitutes forstorage chip 9, main control chip and the required D.C. regulated power supply of zero cross detection circuit 7 work through a voltage stabilizing didoe 19; One by-pass cock 8 is composed in parallel bymode switch 81 andspeed switch 82, one end ground connection, and the other end connects two different pins on the main control chip respectively; One storage chip, one end ground connection, another termination main control chip; Be connected to a zero cross detection circuit between city's power supply and main control chip, this circuit is to be made of 71,72 parallel connections of two photoelectrical couplers.

Above illustrated embodiment only with convenient explanation the present invention, is not breaking away from creation spirit scope of the present invention, is familiar with any simple covert and modification that the personage did of this technology, must be contained in the scope of the present invention.

Claims (3)

1. method of controlling LED brightness, it is characterized in that: utilize controllable silicon to control " bright " and " going out " state of LED by zero-crossing switching, and send the unlatching that trigger impulse comes driving LED by CPU, wherein, described controllable silicon makes the part-time of LED in the one-period of the pulse power or AC power be in " bright " state and be in " going out " state in all the other times, and the trigger impulse that described CPU sends in good time is used to control the opening time that LED is in bright state.

2. the method for control LED according to claim 1 brightness, it is characterized in that: described controllable silicon is an one-way SCR.

3. the method for control LED according to claim 1 brightness, it is characterized in that: described CPU is a singlechip chip EM78P153SN.

Images