CN210442669U - Compensation circuit for LCD display contrast - Google Patents
Compensation circuit for LCD display contrast Download PDFInfo
- Publication number
- CN210442669U CN210442669U CN201921944284.4U CN201921944284U CN210442669U CN 210442669 U CN210442669 U CN 210442669U CN 201921944284 U CN201921944284 U CN 201921944284U CN 210442669 U CN210442669 U CN 210442669U
- Authority
- CN
- China
- Prior art keywords
- lcd
- resistor
- npn triode
- resistance
- omega
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Landscapes
- Liquid Crystal Display Device Control (AREA)
Abstract
The utility model discloses a LCD shows compensation circuit of contrast, its compensation circuit that adopts 3 NPN triodes and a PNP triode and 6 resistance to constitute. When the backlight needs to be lightened, the MCU outputs a high-level control signal to improve the output voltage of the voltage stabilizing circuit, and the display driving voltage of the LCD is improved to change the display contrast of the LCD. When the backlight is not bright, the MCU outputs a low-level control signal to reduce the output voltage of the voltage stabilizing circuit and reduce the display driving voltage of the LCD to change the display contrast of the LCD. The utility model discloses a compensating circuit has adopted different steady voltage points, has compensated the liquid crystal and has lighted the demonstration under the backlight two kinds of states, makes it in keeping best demonstration contrast.
Description
Technical Field
The utility model relates to a LCD shows technical field, especially relates to a compensating circuit of LCD demonstration contrast.
Background
In the existing black-white Liquid Crystal Display (LCD), the higher the driving voltage is, the darker and darker the display is, and the lower the driving voltage is, the darker and lighter the display is. The liquid crystal screen is widely applied to electric meter display screens, calculator display screens, humiture product display screens, timer product display screens, weather forecast product display screens and the like. The application of the product mainly comprises the following two modes, one mode is that the product is directly powered by a dry battery with 3.3V without voltage stabilization, and the product has a backlight function; the other is to adopt LDO voltage stabilization 2.5V-3V to supply power to the MCU, and the product is provided with backlight.
The dry battery directly supplies power for display, the new battery is not lighted at 3.3V and is displayed in a backlight mode at normal temperature, and the contrast is high; the backlight is lit and the battery voltage drops showing a contrast degradation blur. The LDO voltage stabilization 2.5V-3V is adopted for power supply, the contrast ratio of non-bright backlight display at normal temperature is high, the contrast ratio of bright backlight display at normal temperature is poor because the fonts are illuminated a little.
Disclosure of Invention
An object of the utility model is to provide a compensating circuit of LCD demonstration contrast.
The utility model adopts the technical proposal that:
a compensating circuit for LCD display contrast comprises a PNP triode Q1, an NPN triode Q2, an NPN triode Q3 and an NPN triode Q4, wherein an input power supply V _ IN is connected with an emitting electrode of the PNP triode Q1, a collector electrode of the PNP triode Q1 is used as a liquid crystal voltage output end V _ OUT to be connected with an LCD panel, the input power supply V _ IN is respectively connected with a base electrode of an NPN triode Q2 and a collector electrode of the NPN triode Q3 through a resistor R4, a base electrode of the PNP triode Q1 is connected with a collector electrode of an NPN Q2 through a resistor R1, emitter electrodes of the NPN triode Q2 and an NPN Q3 are grounded, a base electrode of the NPN triode Q3 is respectively connected with one ends of a resistor R3, a resistor R2 and a resistor R5, the other end of the resistor R3 is grounded, the other end of the resistor R2 is connected with a liquid crystal voltage output end V _ OUT, the other end of the resistor R5 is connected with a collector electrode of an NPN, when the LCD displays that the backlight needs to be lightened, the backlight control pin of the microcontroller outputs high level, otherwise, the backlight control pin of the microcontroller outputs low level.
Furthermore, the resistance R1 has a value range of 1K-3M omega, the resistance R2 has a value range of 330K-10M omega, the resistance R3 has a value range of 82K-10M omega, the resistance R4 has a value range of 100K-10M omega, the resistance R5 has a value range of 470K-3M omega, and the resistance R6 has a value range of 1K-1M omega.
Further, the microcontroller is a 51-series single chip microcomputer or an ARM single chip microcomputer.
The utility model adopts the above technical scheme, when the back of the body is bright, microcontroller's control pin in a poor light exports high level, NPN triode Q4 switch on work, resistance R5 ground connection, the voltage of liquid crystal voltage output V _ OUT is 0.6 (R2+ (R3// R5))/(R3// R5), improve LCD's demonstration drive voltage, change LCD's demonstration contrast; when the backlight is not lighted, the backlight control pin of the microcontroller outputs low level, the NPN triode Q4 is cut off, the voltage of V _ OUT is 0.6 (R2+ R3)/R3, and the output voltage of the voltage stabilizing circuit is reduced, so that the display driving voltage of the LCD is reduced, and the display contrast of the LCD is changed. The higher the voltage of the liquid crystal, the darker the display, and the lower the voltage of the liquid crystal, the lighter the display. The circuit of the invention adopts different voltage stabilizing points to compensate the display of the liquid crystal under the two states of bright backlight and non-bright backlight, so that the optimal display contrast is kept.
Drawings
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments;
fig. 1 is a schematic structural diagram of a compensation circuit for LCD contrast ratio.
Detailed Description
As shown IN fig. 1, the present invention discloses a compensation circuit for LCD contrast ratio, which comprises a PNP transistor Q1, an NPN transistor Q2, an NPN transistor Q3, and an NPN transistor Q4, wherein resistors R2 and R3 are sampling resistors, a voltage drop of 0.6V when the NPN transistor Q3 operates at room temperature, an input power V _ IN is connected to an emitter of the PNP transistor Q1, a collector of the PNP transistor Q1 is connected to an LCD panel as a liquid crystal voltage output terminal V _ OUT, the input power V _ IN is connected to a base of the NPN transistor Q2 and a collector of the NPN transistor Q3 through a resistor R4, a base of the PNP transistor Q1 is connected to a collector of the NPN transistor Q2 through a resistor R1, the NPN transistor Q2 and an emitter of the NPN transistor Q3 are grounded, bases of the NPN transistors Q3 are connected to one end of resistors R3, R2 and R5, the other end of the resistor R3 is grounded, and the other end of the resistor R2 is connected to the liquid crystal voltage output terminal V _ OUT, the other end of the resistor R5 is connected with the collector of the NPN triode Q4, the emitter of the NPN triode Q4 is grounded, the base of the NPN triode Q4 is connected with the backlight control pin of the microcontroller through the resistor R6, the backlight control pin of the microcontroller outputs high level when the LCD displays that the backlight needs to be lightened, and otherwise, the backlight control pin of the microcontroller outputs low level.
Furthermore, the resistance R1 has a value range of 1K-3M omega, the resistance R2 has a value range of 330K-10M omega, the resistance R3 has a value range of 82K-10M omega, the resistance R4 has a value range of 100K-10M omega, the resistance R5 has a value range of 470K-3M omega, and the resistance R6 has a value range of 1K-1M omega.
Further, the microcontroller is a 51-series single chip microcomputer or an ARM single chip microcomputer.
The utility model adopts the above technical scheme, when the back of the body is bright, microcontroller's control pin in a poor light exports high level, NPN triode Q4 switch on work, resistance R5 ground connection, the voltage of liquid crystal voltage output V _ OUT is 0.6 (R2+ (R3// R5))/(R3// R5), improve LCD's demonstration drive voltage, change LCD's demonstration contrast; when the backlight is not lighted, the backlight control pin of the microcontroller outputs low level, the NPN triode Q4 is cut off, the voltage of V _ OUT is 0.6 (R2+ R3)/R3, and the output voltage of the voltage stabilizing circuit is reduced, so that the display driving voltage of the LCD is reduced, and the display contrast of the LCD is changed. The higher the voltage of the liquid crystal, the darker the display, and the lower the voltage of the liquid crystal, the lighter the display. The circuit of the invention adopts different voltage stabilizing points to compensate the display of the liquid crystal under the two states of bright backlight and non-bright backlight, so that the optimal display contrast is kept.
Claims (3)
1. A kind of LCD shows the compensating circuit of the contrast, characterized by that: the compensation circuit is a circuit formed by a plurality of triodes, and specifically comprises a PNP triode Q1, an NPN triode Q2, an NPN triode Q3 and an NPN triode Q4, wherein an input power supply V _ IN is connected with an emitting electrode of the PNP triode Q1, a collector electrode of the PNP triode Q1 is used as a liquid crystal voltage output end V _ OUT to be connected with an LCD panel, the input power supply V _ IN is respectively connected with a base electrode of an NPN triode Q2 and a collector electrode of the NPN triode Q3 through a resistor R4, a base electrode of the PNP triode Q1 is connected with a collector electrode of the NPN triode Q2 through a resistor R1, emitter electrodes of the NPN triode Q2 and the NPN triode Q3 are grounded, a base electrode of the NPN triode Q3 is respectively connected with one ends of a resistor R3, a resistor R2 and a resistor R5, the other end of the resistor R3 is grounded, the other end of the resistor R2 is connected, the base of the NPN triode Q4 is connected with a backlight control pin of the microcontroller through a resistor R6, when the LCD lights the backlight, the backlight control pin of the microcontroller outputs high level, otherwise, the backlight control pin of the microcontroller outputs low level.
2. A compensation circuit for LCD display contrast according to claim 1, wherein: the resistance R1 has a value range of 1K-3M omega, the resistance R2 has a value range of 330K-10M omega, the resistance R3 has a value range of 82K-10M omega, the resistance R4 has a value range of 100K-10M omega, the resistance R5 has a value range of 470K-3M omega, and the resistance R6 has a value range of 1K-1M omega.
3. A compensation circuit for LCD display contrast according to claim 1, wherein: the microcontroller is a 51-series single chip microcomputer or an ARM single chip microcomputer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921944284.4U CN210442669U (en) | 2019-11-12 | 2019-11-12 | Compensation circuit for LCD display contrast |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921944284.4U CN210442669U (en) | 2019-11-12 | 2019-11-12 | Compensation circuit for LCD display contrast |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN210442669U true CN210442669U (en) | 2020-05-01 |
Family
ID=70412133
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201921944284.4U Expired - Fee Related CN210442669U (en) | 2019-11-12 | 2019-11-12 | Compensation circuit for LCD display contrast |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN210442669U (en) |
-
2019
- 2019-11-12 CN CN201921944284.4U patent/CN210442669U/en not_active Expired - Fee Related
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN100573642C (en) | The LED control circuit | |
| CN204695646U (en) | Multifunctional digital code pipe display brassboard | |
| CN102006696B (en) | Light-emitting diode backlight drive circuit, method and constant current source thereof | |
| CN210442669U (en) | Compensation circuit for LCD display contrast | |
| CN202189539U (en) | Adaptive adjustment LED (light-emitting diode) backlight circuit | |
| CN201429968Y (en) | User device and backlight driving circuit thereof | |
| CN211128322U (en) | Display screen panel capable of adjusting lettering backlight brightness | |
| CN221227779U (en) | LED brightness control circuit | |
| CN207718782U (en) | A kind of band disappears the UHD liquid-crystalline glasses panel circuit structures of shadow circuit | |
| CN204557997U (en) | Photoelectricity drawing board | |
| CN210804044U (en) | Circuit for controlling constant display of LCD through temperature drift of triode | |
| CN107680553B (en) | Gray scale display segment code liquid crystal screen and gray scale display method thereof | |
| CN220526567U (en) | LCD drive control circuit | |
| CN218336505U (en) | LED constant current drive circuit and electronic equipment | |
| CN207572050U (en) | Grayscale display segment code liquid crystal display | |
| CN207425325U (en) | A kind of double backlight control circuits of LED and double backlight LED matrixs | |
| CN217740145U (en) | High-temperature liquid crystal display module | |
| CN112363426B (en) | Intelligent power-on system | |
| CN219107709U (en) | Keyboard backlight brightness adjusting circuit, keyboard and electronic equipment | |
| CN212009000U (en) | Accurate weather forecast machine | |
| CN220474318U (en) | Bluetooth digital display screen | |
| CN210429270U (en) | Light modulation device and display device | |
| CN211087889U (en) | Single-color STN liquid crystal screen contrast automatic compensation circuit | |
| CN204946514U (en) | Can low temperature use LCD MODULE | |
| CN2605368Y (en) | Colour-changing window |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20200501 Termination date: 20211112 |
|
| CF01 | Termination of patent right due to non-payment of annual fee |