CN102903338A - Liquid crystal backlight control circuit for automobile air conditioner - Google Patents
Liquid crystal backlight control circuit for automobile air conditioner Download PDFInfo
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- CN102903338A CN102903338A CN2012104062440A CN201210406244A CN102903338A CN 102903338 A CN102903338 A CN 102903338A CN 2012104062440 A CN2012104062440 A CN 2012104062440A CN 201210406244 A CN201210406244 A CN 201210406244A CN 102903338 A CN102903338 A CN 102903338A
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Abstract
The invention discloses a liquid crystal backlight control circuit for an automobile air conditioner, which comprises a negative feedback circuit and more than one branch lighting circuit, wherein the negative feedback circuit comprises a first resistor, a first triode, a second resistor and a third triode; one end of the first resistor is connected with the output end of a pulse width modulation signal output by an MCU (micro control unit), and the other end of the first resistor is connected with the base electrode of the first triode and the collector electrode of the second triode; one end of the second resistor is connected with the base electrode of the second triode and the emitter electrode of the first triode, and the other end of the second resistor is grounded; any one of the branch lighting circuits is composed of a branch resistor, a branch triode and at least one branch LED (light emitting diode); one end of the branch resistor is connected with the positive electrode of a battery, and the other end of the branch resistor is connected with the emitter electrode of the branch triode; the collector electrode of the branch triode is connected with the positive electrode of the branch LED; the negative electrode of the branch LED is connected with the base electrode of the first triode; and the base electrode of the branch triode is connected with the emitter electrode of the second triode.
Description
Technical field
The present invention relates to a kind of control device, particularly a kind of automobile air conditioner LCD backlight control circuit.
Background technology
At present, much automotive air-conditioning controllers adopt liquid crystal display to show air-conditioning states, and most of LED that adopts is as LCD backlight lamp source aspect LCD backlight, and the characteristics of LED are that color is much available, and ratio is from vehement streetlamp energy-saving.But when requiring between power supply DC9V-DC16V owing to automobile, component working is normal.And adopt method LED brightness on so wide power supply of existing resistance in series current limliting to change too greatly.
In the prior art, LED lighting circuit commonly used has following several: 1, LED and current-limiting resistance are cascaded, and then anode and the negative terminal with power supply connects.Sort circuit is the simplest, however the electric current of LED change along with the change of cell voltage, thereby cause the brightness meeting that significant the variation occurs.2, increasing a switch triode on the basis of 1 circuit, by the MCU(microcontroller of automobile ECU zhong) pwm signal of output comes the Push And Release of gauge tap triode.When cell voltage raises, reduce the dutycycle of pwm signal; When cell voltage reduces, the dutycycle of rising pwm signal.Sort circuit improves to a certain extent by cell voltage and changes the impact bring, can't accomplish response at a high speed yet MCU detects battery, when cell voltage when there is larger variation the very short time, the brightness of LED still can allow the findable variation of passenger.3, adopt the power supply chip of voltage stabilizing to produce a stable voltage on 1 basis.The cost of sort circuit meeting a larger increase circuit, when the driving multi-string LED needed larger electric current, the heat radiation of power supply chip also can become a problem.4, the constant-current circuit that is comprised of two triodes, the be knot of one of them triode is as current detection circuit.The problem that preferably treatment of battery voltage fluctuation of sort circuit brings, but when temperature changed, the voltage of the be of triode knot can change along with temperature, thereby causes the relatively poor temperature characterisitic of sort circuit, when temperature change, the brightness of LED also can change thereupon.
Summary of the invention
The technical problem to be solved in the present invention is can provide a kind of automobile air conditioner LCD backlight control circuit with the technical matters that cell voltage changes for the existing automobile LED backlight illumination of prior art.
For achieving the above object, the technical solution adopted in the present invention is as follows:
A kind of automobile air conditioner LCD backlight control circuit comprises the branch road lighting circuit of a negative-feedback circuit and an above number, and described negative-feedback circuit is by the first resistance, the first triode, the second resistance, the 3rd triode; One end of described the first resistance is connected with the pulse width modulating signal output terminal of MCU output, the other end of the first resistance is connected with the base stage of the first triode and is connected the collector of triode and connects, one end of the second resistance and the base stage of the second triode be connected the emitter of triode and be connected the other end ground connection of the second resistance; Any one described branch road lighting circuit all each free branch road resistance, a branch road triode and at least one paths of LEDs consists of, in any one branch road lighting circuit, one end of described branch road resistance is connected with the positive pole of battery, the other end of branch road resistance is connected on the emitter of branch road triode, the collector of branch road triode is connected on the positive pole of a paths of LEDs, the negative pole that props up paths of LEDs is connected on the base stage of the first triode, and the base stage of branch road triode is connected on the emitter of the second triode.
The resistance of described the second resistance is 0.01-1 Ω.
The model of described the second triode is 2N2222.
By technique scheme, the invention has the beneficial effects as follows:
When the brightness of liquid crystal of the present invention changed in the scope of power supply from DC9V to DC16V of car, liquid crystal brightness was without significant change.
Description of drawings
In order to be illustrated more clearly in the embodiment of the invention or technical scheme of the prior art, the below will do to introduce simply to the accompanying drawing of required use in embodiment or the description of the Prior Art, apparently, accompanying drawing in the following describes only is some embodiments of the present invention, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain according to these accompanying drawings other accompanying drawing.
Fig. 1 is circuit diagram of the present invention.
Embodiment
For technological means, creation characteristic that the present invention is realized, reach purpose and effect is easy to understand, below in conjunction with concrete diagram, further set forth the present invention.
Referring to shown in Figure 1, a kind of automobile air conditioner LCD backlight control circuit comprises branch road lighting circuit L1, the L2 of a negative-feedback circuit and an above number ... Ln, negative-feedback circuit is by resistance R a, Rb, triode TR1, TR2; The pulse width modulating signal output terminal CTR of the end of resistance R a and MCU output is connected, and the other end of resistance R a is connected with the base stage of triode TR1 is connected the collector connection with triode TR2; The end of resistance R b and the base stage of triode TR2 are connected emitter and are connected other end ground connection with triode TR1.
Any one branch road lighting circuit L1, L2 ... Ln is each free branch road resistance R 1 all, R2 ... Rn, branch road triode Q1, Q2 ... Qn, branch road LEDL1, L2 ... Ln, in each branch road lighting circuit, branch road resistance R 1, R2 ... the end of Rn is connected with the anodal v of battery, branch road resistance R 1, R2 ... the other end of Rn is connected to branch road triode Q1, Q2 ... on the emitter of Qn, branch road triode Q1, Q2 ... the collector of Qn is connected to branch road LEDL1, L2 ... on the positive pole of Ln, branch road LEDL1, L2 ... the negative pole of Ln is connected on the base stage of triode TR1, branch road triode Q1, Q2 ... the base stage of Qn is connected on the emitter of triode TR2.The resistance of resistance R b is 0.01-1 Ω.The model of triode TR2 is 2N2222.
The present invention has overcome when temperature changes, the problem that the brightness of the LED that causes also can change thereupon.
More than show and described ultimate principle of the present invention and principal character and advantage of the present invention.The technician of the industry should understand; the present invention is not restricted to the described embodiments; that describes in above-described embodiment and the instructions just illustrates principle of the present invention; without departing from the spirit and scope of the present invention; the present invention also has various changes and modifications, and these changes and improvements all fall in the claimed scope of the invention.The claimed scope of the present invention is defined by appending claims and equivalent thereof.
Claims (3)
1. automobile air conditioner LCD backlight control circuit comprises the branch road lighting circuit of a negative-feedback circuit and an above number, and described negative-feedback circuit is by the first resistance, the first triode, the second resistance, the 3rd triode; One end of described the first resistance is connected with the pulse width modulating signal output terminal of MCU output, the other end of the first resistance is connected with the base stage of the first triode and is connected the collector of triode and connects, one end of the second resistance and the base stage of the second triode be connected the emitter of triode and be connected the other end ground connection of the second resistance; Any one described branch road lighting circuit all each free branch road resistance, a branch road triode and at least one paths of LEDs consists of, in any one branch road lighting circuit, one end of described branch road resistance is connected with the positive pole of battery, the other end of branch road resistance is connected on the emitter of branch road triode, the collector of branch road triode is connected on the positive pole of a paths of LEDs, the negative pole that props up paths of LEDs is connected on the base stage of the first triode, and the base stage of branch road triode is connected on the emitter of the second triode.
2. automobile air conditioner LCD backlight control circuit as claimed in claim 1 is characterized in that, the resistance of described the second resistance is 0.01-1 Ω.
3. automobile air conditioner LCD backlight control circuit as claimed in claim 1 is characterized in that, the model of described the second triode is 2N2222.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2012104062440A CN102903338A (en) | 2012-10-22 | 2012-10-22 | Liquid crystal backlight control circuit for automobile air conditioner |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2012104062440A CN102903338A (en) | 2012-10-22 | 2012-10-22 | Liquid crystal backlight control circuit for automobile air conditioner |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN102903338A true CN102903338A (en) | 2013-01-30 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2012104062440A Pending CN102903338A (en) | 2012-10-22 | 2012-10-22 | Liquid crystal backlight control circuit for automobile air conditioner |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN102903338A (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2355238A1 (en) * | 1999-10-15 | 2001-04-19 | Matsushita Electric Industrial Co., Ltd. | Optical modulator |
| CN101311778A (en) * | 2007-05-24 | 2008-11-26 | 上海福太隆汽车电子科技有限公司 | Automobile air conditioner LCD backlight control circuit |
| CN201425670Y (en) * | 2009-04-17 | 2010-03-17 | 东莞市飞尔液晶显示器有限公司 | liquid crystal module |
| WO2012022235A1 (en) * | 2010-08-19 | 2012-02-23 | 深圳市明微电子股份有限公司 | Method and device for frequency multiplication of display control |
| CN202363086U (en) * | 2011-11-10 | 2012-08-01 | 上海福太隆汽车电子科技有限公司 | Automobile air-conditioning liquid crystal backlight control circuit |
-
2012
- 2012-10-22 CN CN2012104062440A patent/CN102903338A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2355238A1 (en) * | 1999-10-15 | 2001-04-19 | Matsushita Electric Industrial Co., Ltd. | Optical modulator |
| CN101311778A (en) * | 2007-05-24 | 2008-11-26 | 上海福太隆汽车电子科技有限公司 | Automobile air conditioner LCD backlight control circuit |
| CN201425670Y (en) * | 2009-04-17 | 2010-03-17 | 东莞市飞尔液晶显示器有限公司 | liquid crystal module |
| WO2012022235A1 (en) * | 2010-08-19 | 2012-02-23 | 深圳市明微电子股份有限公司 | Method and device for frequency multiplication of display control |
| CN202363086U (en) * | 2011-11-10 | 2012-08-01 | 上海福太隆汽车电子科技有限公司 | Automobile air-conditioning liquid crystal backlight control circuit |
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Application publication date: 20130130 |