CN203645892U - Constant current adjustable backlight circuit - Google Patents
Constant current adjustable backlight circuit Download PDFInfo
- Publication number
- CN203645892U CN203645892U CN201320879680.XU CN201320879680U CN203645892U CN 203645892 U CN203645892 U CN 203645892U CN 201320879680 U CN201320879680 U CN 201320879680U CN 203645892 U CN203645892 U CN 203645892U
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- circuit
- constant current
- pwm
- resistance
- feedback
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/40—Control techniques providing energy savings, e.g. smart controller or presence detection
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- Circuit Arrangement For Electric Light Sources In General (AREA)
Abstract
The utility model provides a constant current adjustable backlight circuit which comprises a PWM circuit (1), an RC integral shaping circuit (2), a constant current control and feedback circuit (3) and an LED backlight source (4). The PWM circuit (1) produces a needed PWM pulse width adjustment waveform. The RC integral shaping circuit (2) carries out integral shaping on the PWM waveform produced by the PWM circuit (1), so as to form a stable direct current voltage source. The constant current control and feedback circuit (3) carries out voltage-dividing limiting and feedback on the stable direct current voltage source acquired by the integral shaping of the RC integral shaping circuit (2), so that constant current control and feedback is realized, and the LED backlight source (4) driven by constant current is produced. The constant current adjustable backlight circuit provided by the utility model has the advantages of less components, simple and reliable circuit realization, ingenious design, excellent performance, and being convenient and practical.
Description
Technical field
The utility model is a kind of constant current dimmable backlights circuit, belongs to the renovation technique of constant current dimmable backlights circuit.
Background technology
At present, traditional backlight drive circuit is LED-backlit steady operation by resistance current limliting, the fatal shortcoming of sort circuit is: 1, the existence of resistance R is necessary, active loss on R directly affects the efficiency of system, when R dividing potential drop accounts for 40% of total output voltage compared with the pressure drop of hour R, output circuit active loss on R has accounted for 40%.2, whether very accurately the otherness of various each LED-backlit own has determined a pressure drop backlight value own, and electric current is a specific factor that affects backlight illumination, once the electric current by itself is inconsistent, by causing the inconsistent of luminosity, occurs brightness disproportionation.
Can to make LED-backlit steady operation in order reaching, to keep again high efficiency, should adopt the current limiting element of low-power consumption and circuit to make the current limiting element of system effect low-power consumption and circuit that system effectiveness is improved.
LED-backlit need to have the element of current stabilization, voltage stabilizing in the time of work, it is high that but this class component should possess the dividing potential drop of self bearing, but power consumption is wanted little characteristic, otherwise by making the LED-backlit with greater efficiency because the work power consumption of drive circuit is too large, the efficiency of overall system greatly be reduced, run counter to the aim of efficient energy-saving.So should not adopt as far as possible resistance or serial regulating circuit to be used as the current limliting main circuit of LED-backlit driver, and should adopt electric capacity, the efficient circuits such as inductance or active switch circuit, the high efficiency of guarantee LED-backlit system like this.Adopt constant-current source can be stable be that it is luminous.
Aspect light modulation, LED-backlit not only can realize 0～100% light modulation, and can guarantee to keep high light effect in whole light modulation process, and do not damage the life-span of LED-backlit, gaseous discharge lamp is difficult to accomplish this point, and constant-current dimming circuit can be realized 0～100% light modulation, and can realize the light modulation of flicker free.
Most of backlight drive typical circuits generally select pwm chip and current-limiting resistance to realize, and the time of lighting by control LED-backlit and the size of current flowing are controlled its brightness.The following technology of the general employing of backlight drive circuit: the time is lighted in pwm chip control, is connected in series a current-limiting resistance, and the Current Control during conducting realizes backlight drive in the working range of LED-backlit.
But still there are in actual applications some problems in this protective circuit:
1) existence turning on and off due to PWM, LED-backlit inevitably can go out first flicker, no matter be that can human eye identify, flicker is exist actually.
2) corresponding traditional LED-backlit drives, and current limliting backlight realizes by current-limiting resistance, can not realize electric current easily and regulate.
3) traditional LED-backlit drive circuit, the realization of brightness regulation backlight, be use PWM such by making low-light level, time flicker is more violent.
In sum, for backlight drive, need a kind of reliable and practical drive circuit to solve above problem.
Summary of the invention
The purpose of this utility model is to consider the problems referred to above and provides a kind of number of elements few, and circuit is realized simple and reliable constant current dimmable backlights circuit.The utility model is reasonable in design, convenient and practical.
The technical solution of the utility model is: constant current dimmable backlights circuit of the present utility model, include pwm circuit, RC integration shaping circuit, constant current control and feedback circuit and LED-backlit source, and described pwm circuit produces the pwm pulse width adjustment waveform needing; The PWM waveform that RC integration shaping circuit produces pwm circuit carries out integration shaping, forms a galvanic current potential source; The stable DC voltage source obtaining after the shaping of RC integration shaping circuit integration is carried out dividing potential drop current limliting and feedback by constant current control and feedback circuit, realizes constant current control and feedback, produces a constant current driven LED-backlit source.
Said PWM circuit is the square wave generation circuit that can regulate.
Above-mentioned RC integration shaping circuit is made up of resistance R 1 and capacitor C 1, and one end of resistance R 1 is connected with the output of pwm circuit, and the other end of resistance R 1 is connected with one end of capacitor C 1 and is connected with constant current control and feedback circuit, the other end ground connection of capacitor C 1.
Above-mentioned constant current control and feedback circuit include triode Q1 and resistance R 3, the base stage of triode Q1 is connected with one end of resistance R 1 and capacitor C 1, the collector electrode of triode Q1 is connected with LED-backlit source, and the emitter of triode Q1 is connected with one end of resistance R 3, the other end ground connection of resistance R 3.
Above-mentioned LED-backlit source is common LED backlight, includes LED light source.
The utility model is because employing includes the structure in pwm circuit, RC integration shaping circuit, constant current control and feedback circuit and LED-backlit source, and pwm circuit produces the pwm pulse width adjustment waveform needing; The PWM waveform that RC integration shaping circuit produces pwm circuit carries out integration shaping, forms a galvanic current potential source; The stable DC voltage source obtaining after the shaping of RC integration shaping circuit integration is carried out dividing potential drop current limliting and feedback by constant current control and feedback circuit, realizes constant current control and feedback, produces a predictable constant current, thus the driving LED backlight of even flicker free.The utility model number of elements is few, and circuit is realized simple and reliable, is that a kind of design is ingenious, function admirable, convenient and practical constant current dimmable backlights circuit.
Accompanying drawing explanation
Fig. 1 is schematic diagram of the present utility model.
Embodiment
Embodiment:
Schematic diagram of the present utility model as shown in Figure 1, constant current dimmable backlights circuit of the present utility model, include pwm circuit 1, RC integration shaping circuit 2, constant current control and feedback circuit 3 and LED-backlit source 4, described pwm circuit 1 produces the pwm pulse width adjustment waveform needing; The PWM waveform that RC integration shaping circuit 2 produces pwm circuit 1 carries out integration shaping, forms a galvanic current potential source; The stable DC voltage source obtaining after the 2 integration shapings of RC integration shaping circuit is carried out dividing potential drop current limliting and feedback by constant current control and feedback circuit 3, realizes constant current control and feedback, produces a constant current driven LED-backlit source 4.
Said PWM circuit 1 is the square wave generation circuit that can regulate.In practical application, pwm circuit 1 produces the pwm pulse width adjustment waveform needing, and can adopt Single Chip Microcomputer (SCM) system to produce adjustable impulse waveform, also can adopt the adjustable Waveform generating circuit of other pulse durations.
In the present embodiment, above-mentioned RC integration shaping circuit 2 is made up of resistance R 1 and capacitor C 1, one end of resistance R 1 is connected with the output of pwm circuit 1, and the other end of resistance R 1 is connected with one end of capacitor C 1 and is connected with constant current control and feedback circuit 3, the other end ground connection of capacitor C 1.
In the present embodiment, above-mentioned constant current control and feedback circuit 3 include triode Q1 and resistance R 3, the base stage of triode Q1 is connected with one end of resistance R 1 and capacitor C 1, the collector electrode of triode Q1 is connected with LED-backlit source (4), the emitter of triode Q1 is connected with one end of resistance R 3, the other end ground connection of resistance R 3.
In the present embodiment, above-mentioned LED-backlit source 4 is common LED backlight, includes LED light source.
Operation principle of the present utility model is as follows: with reference to Fig. 1, described pwm circuit 1 produces the pwm pulse width adjustment waveform needing, the PWM waveform that RC integration shaping circuit 2 produces pwm circuit 1 carries out integration shaping, by resistance R 1, to C1 charging, the frequency producing take pwm circuit 1 is as according to selecting suitable R1 resistance value and the suitable capacitance of C1 to show that RC integration shaping circuit obtain direct voltage source stably.Again by the V of triode Q1
bEwith flow to and form loop by R3, in this loop, V
bEfor 0.7V, when R3 resistance value is determined, can make the collector electrode C place of triode Q1 obtain a constant electric current I
c=(V
a-V
bE)/R3.In pwm circuit 1 and RC integration shaping circuit 2 these two circuit, select the waveform (comprising suitable frequency and pulsewidth width) of suitable PWM can obtain a galvanic current pressure VA, obtain different VA by adjusting the parameter of resistance R 1 and C1 in the pulse duration model that produces in pwm circuit 1 and RC integration shaping circuit 2, thereby obtain different constant currents, realize constant-current dimming.
Claims (5)
1. a constant current dimmable backlights circuit, it is characterized in that including pwm circuit (1), RC integration shaping circuit (2), constant current control and feedback circuit (3) and LED-backlit source (4), described pwm circuit (1) produces the pwm pulse width adjustment waveform needing; The PWM waveform that RC integration shaping circuit (2) produces pwm circuit (1) carries out integration shaping, forms a galvanic current potential source; The stable DC voltage source obtaining after RC integration shaping circuit (2) integration shaping is carried out dividing potential drop current limliting and feedback by constant current control and feedback circuit (3), realizes constant current control and feedback, produces a constant current driven LED-backlit source (4).
2. constant current dimmable backlights circuit according to claim 1, is characterized in that said PWM circuit (1) is the square wave generation circuit that can regulate.
3. constant current dimmable backlights circuit according to claim 1, it is characterized in that above-mentioned RC integration shaping circuit (2) is made up of resistance R 1 and capacitor C 1, one end of resistance R 1 is connected with the output of pwm circuit (1), the other end of resistance R 1 is connected with one end of capacitor C 1 and is connected the other end ground connection of capacitor C 1 with constant current control and feedback circuit (3).
4. constant current dimmable backlights circuit according to claim 1, it is characterized in that above-mentioned constant current control and feedback circuit (3) include triode Q1 and resistance R 3, the base stage of triode Q1 is connected with one end of resistance R 1 and capacitor C 1, the collector electrode of triode Q1 is connected with LED-backlit source (4), the emitter of triode Q1 is connected with one end of resistance R 3, the other end ground connection of resistance R 3.
5. constant current dimmable backlights circuit according to claim 1, is characterized in that above-mentioned LED-backlit source (4), for common LED backlight, includes LED light source.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320879680.XU CN203645892U (en) | 2013-12-30 | 2013-12-30 | Constant current adjustable backlight circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320879680.XU CN203645892U (en) | 2013-12-30 | 2013-12-30 | Constant current adjustable backlight circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN203645892U true CN203645892U (en) | 2014-06-11 |
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ID=50877106
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201320879680.XU Expired - Fee Related CN203645892U (en) | 2013-12-30 | 2013-12-30 | Constant current adjustable backlight circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN203645892U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110289836A (en) * | 2019-05-29 | 2019-09-27 | 晶晨半导体(上海)股份有限公司 | A kind of adjusting method for realizing pulse width signal delay |
| CN115280258A (en) * | 2020-03-23 | 2022-11-01 | 株式会社自动网络技术研究所 | Current control device, switch control device, current control method, and computer program |
-
2013
- 2013-12-30 CN CN201320879680.XU patent/CN203645892U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110289836A (en) * | 2019-05-29 | 2019-09-27 | 晶晨半导体(上海)股份有限公司 | A kind of adjusting method for realizing pulse width signal delay |
| CN115280258A (en) * | 2020-03-23 | 2022-11-01 | 株式会社自动网络技术研究所 | Current control device, switch control device, current control method, and computer program |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20140611 Termination date: 20181230 |