CN113744695A - Low-cost LED backlight control circuit applied to station terminal - Google Patents
Low-cost LED backlight control circuit applied to station terminal Download PDFInfo
- Publication number
- CN113744695A CN113744695A CN202110889324.5A CN202110889324A CN113744695A CN 113744695 A CN113744695 A CN 113744695A CN 202110889324 A CN202110889324 A CN 202110889324A CN 113744695 A CN113744695 A CN 113744695A
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- led
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- low
- control circuit
- backlight control
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
- G09G3/3406—Control of illumination source
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
- G09G3/3406—Control of illumination source
- G09G3/3413—Details of control of colour illumination sources
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- General Physics & Mathematics (AREA)
- Theoretical Computer Science (AREA)
- Control Of Indicators Other Than Cathode Ray Tubes (AREA)
- Liquid Crystal Display Device Control (AREA)
- Circuit Arrangement For Electric Light Sources In General (AREA)
Abstract
The invention belongs to the technical field of electronic circuits, and particularly relates to a low-cost LED backlight control circuit applied to a station terminal. The first input PWM is connected with the external signal as a control chip MCU. The first output end LED + is connected with an externally connected signal which is the LED + of the liquid crystal screen. The power switch circuit comprises a high level driving circuit and a switch circuit. The circuit is composed of 3 triodes, 1 PMOS and 6 resistors. The invention has simple structure, small requirement on driving current, high response speed, high refresh rate, normal work in the environment of actually measuring high temperature of 80 ℃ and low temperature of-40 ℃, low cost compared with an integrated chip and better practicability.
Description
Technical Field
The invention belongs to the technical field of electronic circuits, and particularly relates to a low-cost LED backlight control circuit applied to a station terminal.
Background
The traditional CCFL display screen backlight has low luminous efficiency, poor brightness uniformity and poor color gradation expression, and needs high-voltage driving, namely, the inverter converts direct-current voltage into high-voltage alternating-current signals for supplying power to the cathode ray tube, and most importantly, the service life is short. In order to solve the hard damage of the CCFL, the LED backlight source enters the public visual field, and is more applied in the civil and military fields due to the advantages of low power consumption, long service life, small thickness and the like. LEDs not only have ultra-clear color expressiveness and saturation, but also have better applications in video due to high refresh rate performance.
With the development of the application of the LED backlight in the electronic circuit technology, the backlight driving control circuit based on the chip platform is more and more common, but for the small-sized lcd with several or more than ten LED lamps, not only the resource is wasted, but also the price is high, which is not favorable for the cost control in the mass production.
Currently, LEDs are used in series, and in order to enhance the anti-interference capability of a liquid crystal screen, the LEDs of the flat cables are often processed in a shielding mode, so that high-voltage driving control needs to be realized; in addition, because the parasitic capacitance of the LED is large, when the LED is turned off, the voltage leakage time of the parasitic capacitance of the LED needs millisecond level, and the refresh frequency of the PWM is microsecond level, so that the brightness adjustment cannot be realized. By adopting the triode driving circuit, the triode in the amplification region can not only support high level, but also control the driving current and the partial pressure of the MOS by adjusting the resistance of the collector, thereby influencing the switching speed of the MOS; by adopting the scheme of synchronously controlling the double triodes by PWM, the LED power supply can not only realize the synchronization with the switch MOS, and the discharge speed is higher than the refreshing speed of PWM, but also discharge when the LED is turned off, thereby realizing no power loss.
Disclosure of Invention
Based on the above description, the invention provides a low-cost LED backlight control circuit applied to a station terminal.
The technical scheme of the invention is as follows:
a low-cost LED backlight control circuit applied to a station terminal comprises a first input PWM, a first output end LED +, a power switch circuit and a voltage bleeder circuit, wherein the power switch circuit comprises a high-level driving circuit and a switch circuit.
Wherein:
the high level driving circuit includes: the triode VT1, and the resistors R2 and R1 are used for driving the high level V1 by using low level PWM.
The switching circuit includes: PMOS VT4, resistor R3, for the switch channel of high level V1.
The voltage bleeder circuit includes: the LED driving circuit comprises triodes VT2 and VT3 and resistors R4, R5 and R6, and is used for discharging LED parasitic capacitance when the LED is powered off by PWM.
The connection relationship is as follows: the first input PWM is respectively connected with a base of VT1 and one end of R6, an emitter of VT1 is connected with R1, the other end of R1 is connected with GND, a collector of VT1 is connected with R2 and gates of VT4, an electric signal V1 is connected with the other end of R2 and the emitter of VT4, a drain of VT4 is connected with R3, and R3 is connected with first output ends LED + and R4. The other end of R4 is connected with the collector of VT2, the base of VT2 is connected with the collectors of R5 and VT3, the emitter of VT2 and the emitter of VT3 are connected with GND, the other end of R5 is connected with electric signal V2, and the base of VT3 is connected with the other end of R6.
The invention has the beneficial effects that: PWM controls high level drive circuit and voltage bleeder circuit simultaneously, and two circuits work in turn, when guaranteeing to drive high level and give the LED power supply, voltage bleeder circuit closes. When the LED stops supplying power, the voltage relief circuit can timely relieve voltage to ensure that the LED is quickly turned off. The circuit has few devices and stable work, and can meet the requirement of 500k of refresh rate.
Drawings
The invention will be further explained by the following practical examples in conjunction with the attached drawings
Fig. 1 is a block diagram of the circuit configuration of the present invention.
Fig. 2 is a schematic diagram of a low-cost LED backlight control circuit applied to a station terminal according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clearly and clearly understood, the technical solutions in the embodiments of the present invention are further clearly and completely described below with reference to fig. 1 and 2, and it is obvious that the described embodiment is one, but not all, of the embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in figures 1 and 2 of the drawings,
the circuit comprises a first input-output end ILED +, a second input-output end IO2, a first isolation driving circuit and a second isolation driving circuit. Comprises a first input PWM, a first output LED +, a power switch circuit, and a voltage bleeder circuit
The first input PWM is connected with the control chip MCU.
The first output end LED + is connected with an externally connected signal which is the LED + of the liquid crystal screen.
The power switch circuit comprises a high-level driving circuit and a switch circuit.
The high level driving circuit includes: the triode VT1, and the resistors R2 and R1 are used for driving the high level V1 by using low level PWM.
The switching circuit includes: PMOS VT4, resistor R3, for the switch channel of high level V1.
The voltage bleeding circuit includes: the LED driving circuit comprises triodes VT2 and VT3 and resistors R4, R5 and R6, and is used for discharging LED parasitic capacitance when the LED is powered off by PWM.
The connection relation is as follows: the first input PWM is respectively connected with a base of VT1 and one end of R6, an emitter of VT1 is connected with R1, the other end of R1 is connected with GND, a collector of VT1 is connected with R2 and gates of VT4, an electric signal V1 is connected with the other end of R2 and the emitter of VT4, a drain of VT4 is connected with R3, and R3 is connected with first output ends LED + and R4. The other end of R4 is connected with the collector of VT2, the base of VT2 is connected with the collectors of R5 and VT3, the emitter of VT2 and the emitter of VT3 are connected with GND, the other end of R5 is connected with electric signal V2, and the base of VT3 is connected with the other end of R6.
The VT4 is PMOS, and the VT1, VT2 and VT3 are NPN transistors.
Based on the scheme, the working principle of the invention is as follows:
PWM with variable duty cycle. When the PWM is in a high level, the triode VT1 is conducted, the triode VT1 is in a saturation region at the moment, most of the voltage of V1 is shared on Vce, after the partial voltage of R2 meets the conduction requirement of PMOS VT4, the PMOS VT4 is conducted, 01 output voltage is sent to the LED + of the liquid crystal screen, and the LED + passes through a series of LED lamps and then is grounded through an LED-. On the other side, the high level of the PWM enables the triode VT3 to be conducted, the base electrode of the triode VT2 is pulled low, and the triode VT2 is not conducted, namely the voltage of the LED + is not discharged; when the PWM is at low level, the transistor VT1 is not turned on, and at this time, the PMOS VT4 is turned off, and the LED + stops supplying power. On the other side, when the PWM is at low level, the transistor VT3 is not conducting, and at this time, VT2 is conducting due to the pull-up of R5 at the base, and VT2 is conducting, and the LED + voltage is pulled low, and the parasitic capacitance of LED + is discharged.
The PWM duty cycle may control the duration of time that the LED is lit, thereby changing the brightness of the LED.
The circuit of the invention has simple components, low requirement on driving current, high response speed, high refresh rate, low cost compared with an integrated chip and better practicability, and can normally work under the environment of actually measured high temperature of 80 ℃ and low temperature of-40 ℃.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art; the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (5)
1. The low-cost LED backlight control circuit is applied to a station terminal and is characterized by comprising a first input PWM, a first output end LED +, a power switch circuit and a voltage bleeder circuit, wherein the power switch circuit comprises a high-level driving circuit and a switch circuit.
2. The LED backlight control circuit applied to the factory station terminal is characterized in that the first input PWM and the externally connected signal is a control chip MCU.
3. The LED backlight control circuit applied to the factory station terminal in low cost according to claim 2, wherein the first output end LED + is connected to the external signal of LED + of the LCD.
4. The LED backlight control circuit of claim 3, wherein the first input PWM is connected to the base of VT1 and one end of R6, the emitter of VT1 is connected to R1, the other end of R1 is connected to GND, the collector of VT1 is connected to the gates of R2 and VT4, the other end of R2 and the emitter of VT4 are connected to electrical signal V1, the drain of VT4 is connected to R3, and R3 is connected to the first output LED + and R4. The other end of R4 is connected with the collector of VT2, the base of VT2 is connected with the collectors of R5 and VT3, the emitter of VT2 and the emitter of VT3 are connected with GND, the other end of R5 is connected with electric signal V2, and the base of VT3 is connected with the other end of R6.
5. The LED backlight control circuit as claimed in any one of claims 1 to 3, wherein the VT4 is PMOS and the VT1, VT2 and VT3 are NPN transistors.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110889324.5A CN113744695A (en) | 2021-08-04 | 2021-08-04 | Low-cost LED backlight control circuit applied to station terminal |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110889324.5A CN113744695A (en) | 2021-08-04 | 2021-08-04 | Low-cost LED backlight control circuit applied to station terminal |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN113744695A true CN113744695A (en) | 2021-12-03 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110889324.5A Withdrawn CN113744695A (en) | 2021-08-04 | 2021-08-04 | Low-cost LED backlight control circuit applied to station terminal |
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| Country | Link |
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| CN (1) | CN113744695A (en) |
Citations (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TW200820168A (en) * | 2006-10-16 | 2008-05-01 | Chunghwa Picture Tubes Ltd | Light source driving circuit |
| US20090189846A1 (en) * | 2008-01-24 | 2009-07-30 | Hitachi Displays, Ltd. | Liquid Crystal Display Device |
| CN201904072U (en) * | 2010-12-01 | 2011-07-20 | 福建捷联电子有限公司 | LED backlight circuit driven and controlled by Scaler chip in display |
| CN102665325A (en) * | 2012-04-12 | 2012-09-12 | 深圳市华星光电技术有限公司 | LED backlight drive circuit, backlight module and liquid crystal display device |
| US20120306388A1 (en) * | 2011-06-03 | 2012-12-06 | Hoon Jang | Backlight unit and method for driving the same |
| TW201250351A (en) * | 2011-06-03 | 2012-12-16 | Lg Display Co Ltd | Backlight unit and method for driving the same |
| WO2013004061A1 (en) * | 2011-07-01 | 2013-01-10 | 深圳市华星光电技术有限公司 | Led backlight driving circuit |
| DE112013006674T5 (en) * | 2013-03-11 | 2015-11-05 | Shenzhen China Star Optoelectronics Technology Co., Ltd. | Liquid crystal screen and associated LED backlight module |
| CN106683621A (en) * | 2016-12-30 | 2017-05-17 | 厦门厦华科技有限公司 | LED backlight drive circuit and method of realizing soft start |
| CN207977097U (en) * | 2018-03-26 | 2018-10-16 | 广州视源电子科技股份有限公司 | Backlight adjusting protection circuit, backlight adjusting circuit, driving board card and electronic equipment |
| CN208623327U (en) * | 2018-07-25 | 2019-03-19 | 广州视源电子科技股份有限公司 | Discharge circuit |
| CN109729613A (en) * | 2017-10-27 | 2019-05-07 | 深圳Tcl新技术有限公司 | A kind of constant current Drive Protecting Circuit, protective device and television set |
| CN211087888U (en) * | 2019-11-27 | 2020-07-24 | 广州视源电子科技股份有限公司 | Backlight driving circuit and electronic equipment |
| US20200257167A1 (en) * | 2019-02-08 | 2020-08-13 | Sharp Kabushiki Kaisha | Backlight and display device provided with same |
-
2021
- 2021-08-04 CN CN202110889324.5A patent/CN113744695A/en not_active Withdrawn
Patent Citations (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TW200820168A (en) * | 2006-10-16 | 2008-05-01 | Chunghwa Picture Tubes Ltd | Light source driving circuit |
| US20090189846A1 (en) * | 2008-01-24 | 2009-07-30 | Hitachi Displays, Ltd. | Liquid Crystal Display Device |
| CN201904072U (en) * | 2010-12-01 | 2011-07-20 | 福建捷联电子有限公司 | LED backlight circuit driven and controlled by Scaler chip in display |
| US20120306388A1 (en) * | 2011-06-03 | 2012-12-06 | Hoon Jang | Backlight unit and method for driving the same |
| TW201250351A (en) * | 2011-06-03 | 2012-12-16 | Lg Display Co Ltd | Backlight unit and method for driving the same |
| WO2013004061A1 (en) * | 2011-07-01 | 2013-01-10 | 深圳市华星光电技术有限公司 | Led backlight driving circuit |
| CN102665325A (en) * | 2012-04-12 | 2012-09-12 | 深圳市华星光电技术有限公司 | LED backlight drive circuit, backlight module and liquid crystal display device |
| DE112013006674T5 (en) * | 2013-03-11 | 2015-11-05 | Shenzhen China Star Optoelectronics Technology Co., Ltd. | Liquid crystal screen and associated LED backlight module |
| CN106683621A (en) * | 2016-12-30 | 2017-05-17 | 厦门厦华科技有限公司 | LED backlight drive circuit and method of realizing soft start |
| CN109729613A (en) * | 2017-10-27 | 2019-05-07 | 深圳Tcl新技术有限公司 | A kind of constant current Drive Protecting Circuit, protective device and television set |
| CN207977097U (en) * | 2018-03-26 | 2018-10-16 | 广州视源电子科技股份有限公司 | Backlight adjusting protection circuit, backlight adjusting circuit, driving board card and electronic equipment |
| CN208623327U (en) * | 2018-07-25 | 2019-03-19 | 广州视源电子科技股份有限公司 | Discharge circuit |
| US20200257167A1 (en) * | 2019-02-08 | 2020-08-13 | Sharp Kabushiki Kaisha | Backlight and display device provided with same |
| CN211087888U (en) * | 2019-11-27 | 2020-07-24 | 广州视源电子科技股份有限公司 | Backlight driving circuit and electronic equipment |
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| WW01 | Invention patent application withdrawn after publication |
Application publication date: 20211203 |
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| WW01 | Invention patent application withdrawn after publication |