CN202404876U - Vehicular backlight driving circuit - Google Patents
Vehicular backlight driving circuit Download PDFInfo
- Publication number
- CN202404876U CN202404876U CN201120526911XU CN201120526911U CN202404876U CN 202404876 U CN202404876 U CN 202404876U CN 201120526911X U CN201120526911X U CN 201120526911XU CN 201120526911 U CN201120526911 U CN 201120526911U CN 202404876 U CN202404876 U CN 202404876U
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- vehicle
- backlight
- driving circuit
- switching tube
- switch tube
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Abstract
The utility model relates to a vehicular backlight driving circuit, which is used for supplying power for a vehicular backlight light source. One end of the light source is connected with a vehicular power source, the driving circuit comprises a first switch tube, a collector of the first switch tube is connected with the other end of the light source, and an emitter of the first switch tube is grounded through a first resistor. The driving circuit further comprises a second switch tube, a base of the second switch tube is connected with a PWM (pulse-width modulation) signal generator which is used for receiving PWM signals, an emitter of the second switch tube is connected with a constant-voltage source, and a collector of the second switch is connected with a base of the first switch tube. Output current of the vehicular backlight driving circuit is insusceptible to voltage variation of vehicular power sources such as vehicle accumulators and the like, blinking of instrument backlight and LCD (liquid crystal display) backlight is prevented, the service life of the backlight power source is guaranteed, and differentiated backlight control for different functions of meters can be realized.
Description
Technical field
The utility model relates to illumination driving circuit, particularly relates to a kind of vehicle-mounted backlight drive circuit.
Background technology
At present, the combined type automobile instrument is to adopt LED (Lighting Emitting Diode, light emitting diode) illumination as the instrument backlight basically, the general employing of its driving circuit circuit structure as shown in Figure 1.Wherein, the anode of LED is connected to the accumulator output end VB of automobile through resistance R 21, and the negative electrode of LED is through triode Q21 ground connection.The conducting of triode Q21 and by receiving the control of PWM (Pulse Width Modulation, pulse-length modulation) signal, its bright-dark degree is determined by the electric current that flows through LED.According to people's suspenopsia principle, when the frequency of pwm signal was higher than the frequency that human eye can perceive, the said PWM signal acts on the phenomenon that flickers that driving circuit causes LED can be by human eye.
But, the spread of voltage of accumulator output end VB, it is bigger to fluctuate.Among Fig. 1, the voltage drop of two LED on every series arm be assumed to V2, when the PWM port is high level, triode Q21 conducting, the electric current I that then flows through this series arm is: I=(+VB-V2)/R21.So when accumulator output end voltage VB produced fluctuation, the electric current that flows through LED was easy to generate variation.Particularly after the consumers of a lot of big loads on the car start, the voltage of accumulator can be dragged down 1～2V moment sometimes even reach 3～4V, and then automobile instrument is backlight tangible flicker situation can occur.
Summary of the invention
Based on this, be necessary to provide a kind of constant current mode vehicle-mounted backlight drive circuit.
A kind of vehicle-mounted backlight drive circuit is used to vehicle-mounted back light power supply.One end of this light source links to each other with vehicle power.Said driving circuit comprises first switching tube, and the collector of said first switching tube links to each other with the other end of said light source, and the emitter of said first switching tube is through first resistance eutral grounding.Said driving circuit also comprises the second switch pipe; The base stage of said second switch pipe links to each other with a pwm signal generator; Receive pwm signal from said pwm signal generator, the emitter of second switch pipe links to each other with a constant pressure source, and its collector links to each other with the base stage of said first switching tube.
In a preferred embodiment, said pwm signal generator is the automobile microcontroller.
In a preferred embodiment, described vehicle-mounted backlight drive circuit also comprises the stabilivolt that an end ground connection, the other end link to each other with the base stage of said first switching tube.
In a preferred embodiment, described vehicle-mounted backlight drive circuit also comprises second resistance that an end ground connection, the other end link to each other with the base stage of said first switching tube.
In a preferred embodiment, described vehicle-mounted backlight drive circuit also comprises the emitter that is connected said second switch pipe and the 3rd resistance between the base stage.
In a preferred embodiment, the base stage of said second switch pipe links to each other with said pwm signal generator through the 4th resistance.
The output current of the vehicle-mounted backlight drive circuit of the utility model does not receive vehicle power; The for example influence of the change in voltage of automobile storage battery; Prevent the backlight and LCD scintillation that occurs backlight of instrument, the serviceable life of guaranteeing backlight electric power, and can realize the backlight control of instrument difference in functionality differentiation.
Description of drawings
Fig. 1 is the circuit theory diagrams of existing vehicle-mounted backlight drive circuit.
Fig. 2 is the circuit theory diagrams of the vehicle-mounted backlight drive circuit of the utility model one embodiment.
Embodiment
To combine specific embodiment and accompanying drawing that the vehicle-mounted backlight drive circuit of the utility model is described in further detail below.
As shown in Figure 2, among the embodiment, vehicle-mounted backlight drive circuit is the back light power supply of the instrument of vehicle, and this back light is LED (Lighting Emitting Diode, a light emitting diode) lamp.It is an instrument power supply that per six LED lamps are one group, and for example among Fig. 2, it is an instrument power supply that LED D2 to LED D7 is one group, and LED D8 to LED D13 is one group and is another instrument power supply.LED lamp in every group is together in series for two one group and forms three series arms, and then forms a parallel branch.This parallel branch has common anode and common cathode, and wherein anode links to each other with the output terminal VB of vehicle power (being generally accumulator) altogether.Driving circuit with one group of LED lamp is that example describes below.
Vehicle-mounted backlight drive circuit mainly comprises the first switching tube Q1, second switch pipe Q2, first resistance R 1, second resistance R 2, the 3rd resistance R 3, the 4th resistance R 4 and stabilivolt D1.In the present embodiment, the first switching tube Q1 is a NPN type triode, and second switch pipe Q2 is the positive-negative-positive triode, and among other embodiment, also available metal-oxide-semiconductor or IGBT replace.Wherein, the collector of the first switching tube Q1 links to each other with the common cathode of one group of LED lamp, and its emitter is through first resistance R, 1 ground connection, and its base stage links to each other with the collector of second switch pipe Q2.The base stage of the first switching tube Q1 is also through second resistance R, 2 ground connection.The plus earth of stabilivolt D1, negative electrode links to each other with the base stage of the first switching tube Q1.The emitter of second switch pipe Q2 links to each other with a constant pressure source Vin, links to each other with its base stage through the 3rd resistance R 3 simultaneously.This constant pressure source can be shared with other electronic equipments from the automobile mu balanced circuit.The base stage of second switch pipe Q2 links to each other with a pwm signal generator through the 4th resistance R 4.This pwm signal generator be preferably automobile microcontroller (Micro Control Unit, MCU).This MCU can be the special-purpose MCU of driving circuit, also can be shared with modules such as vehicle signal acquisition module, CAN bus communication module and LCD driver modules.This MCU provides a controlled pwm signal to the on off state of second switch pipe Q2 with control second switch pipe Q2.
In the work, second switch pipe Q2 conducting when pwm signal is low level, the base stage that the voltage process second switch pipe Q2 of constant pressure source Vin outputs to the first switching tube Q1 is as its bias voltage.For the emitter of guaranteeing first switching tube Q1 this moment is in conducting state, when the voltage of constant pressure source Vin outputed to the base stage of the first switching tube Q1 through second switch pipe Q2, voltage should be greater than 0.7V.At this moment, the first switching tube Q1 conducting, the LED lamp is luminous.Second switch pipe Q2 ends when pwm signal is high level, and the first switching tube Q1 ends, and the LED lamp extinguishes.The existence of the 3rd resistance R 3 guarantees that when constant pressure source was opened a way, second switch pipe Q2 was in cut-off state.The 4th resistance R 4 is a current-limiting resistance, and second resistance R 2 prevents that the LED lamp is little bright when being first switching tube Q1 shutoff.In other embodiments, can omit stabilivolt D1.
When there being many group LED parallel branches is different instrument or equipment when providing backlight, only needs to increase a plurality of switching tubes, forms parallel branch with the LED parallel branch of foregoing description and the first switching tube Q1 and gets final product, as shown in Figure 2.
The driving circuit of the utility model belongs to triode emitter following type on-off circuit, and under the situation of instrument backlight open, the first switching tube Q1 works in magnifying state, and the total current that flows through LED lamp parallel branch equals to flow through the electric current of first resistance R 1 basically.The voltage of supposing the base stage of the first switching tube Q1 is Vb, and the voltage between base stage and the emitter is Ube, and the resistance of first resistance R 1 is R1, and the electric current I that then flows through first resistance R 1 is: I=(Vb-Ube)/R1.Therefore, the electric current that flows through LED does not receive the variable effect of vehicle power voltage, even the change in voltage 1～4V of vehicle-mounted voltage, brightness of backlight module can not change yet.Also can realize the backlight control of instrument difference in functionality differentiation according to actual needs through the voltage of regulating Vb.
The above embodiment has only expressed several kinds of embodiments of the utility model, and it describes comparatively concrete and detailed, but can not therefore be interpreted as the restriction to the utility model claim.Should be pointed out that for the person of ordinary skill of the art under the prerequisite that does not break away from the utility model design, can also make some distortion and improvement, these all belong to the protection domain of the utility model.Therefore, the protection domain of the utility model patent should be as the criterion with accompanying claims.
Claims (6)
1. a vehicle-mounted backlight drive circuit is used to vehicle-mounted back light power supply, and an end of this light source links to each other with vehicle power; Said driving circuit comprises first switching tube; The collector of said first switching tube links to each other with the other end of said light source, and the emitter of said first switching tube is through first resistance eutral grounding, and it is characterized in that: said driving circuit also comprises the second switch pipe; The base stage of said second switch pipe links to each other with a pwm signal generator; Receive pwm signal from said pwm signal generator, the emitter of second switch pipe links to each other with a constant pressure source, and its collector links to each other with the base stage of said first switching tube.
2. vehicle-mounted backlight drive circuit according to claim 1 is characterized in that, said pwm signal generator is the automobile microcontroller.
3. vehicle-mounted backlight drive circuit according to claim 1 is characterized in that, also comprises the stabilivolt that an end ground connection, the other end link to each other with the base stage of said first switching tube.
4. vehicle-mounted backlight drive circuit according to claim 3 is characterized in that, also comprises second resistance that an end ground connection, the other end link to each other with the base stage of said first switching tube.
5. vehicle-mounted backlight drive circuit according to claim 1 is characterized in that, also comprises the emitter that is connected said second switch pipe and the 3rd resistance between the base stage.
6. vehicle-mounted backlight drive circuit according to claim 5 is characterized in that, the base stage of said second switch pipe links to each other with said pwm signal generator through the 4th resistance.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201120526911XU CN202404876U (en) | 2011-12-16 | 2011-12-16 | Vehicular backlight driving circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201120526911XU CN202404876U (en) | 2011-12-16 | 2011-12-16 | Vehicular backlight driving circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN202404876U true CN202404876U (en) | 2012-08-29 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201120526911XU Expired - Fee Related CN202404876U (en) | 2011-12-16 | 2011-12-16 | Vehicular backlight driving circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN202404876U (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104299577A (en) * | 2014-10-22 | 2015-01-21 | 重庆金宏汽车电子有限公司 | Display control circuit of car navigation system |
| CN108924997A (en) * | 2018-07-05 | 2018-11-30 | 惠州市德赛西威汽车电子股份有限公司 | A kind of second level light adjustment circuit |
| CN113516941A (en) * | 2021-06-22 | 2021-10-19 | 珠海格力电器股份有限公司 | LED matrix brightness control system and method |
-
2011
- 2011-12-16 CN CN201120526911XU patent/CN202404876U/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104299577A (en) * | 2014-10-22 | 2015-01-21 | 重庆金宏汽车电子有限公司 | Display control circuit of car navigation system |
| CN104299577B (en) * | 2014-10-22 | 2016-06-22 | 重庆金宏汽车电子有限公司 | The display control circuit of onboard navigation system |
| CN108924997A (en) * | 2018-07-05 | 2018-11-30 | 惠州市德赛西威汽车电子股份有限公司 | A kind of second level light adjustment circuit |
| CN108924997B (en) * | 2018-07-05 | 2020-03-24 | 惠州市德赛西威汽车电子股份有限公司 | Two-stage light adjusting circuit |
| CN113516941A (en) * | 2021-06-22 | 2021-10-19 | 珠海格力电器股份有限公司 | LED matrix brightness control system and method |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20120829 Termination date: 20131216 |