CN109872698B - Common electrode discharge circuit, source electrode drive circuit and common electrode discharge method - Google Patents
Common electrode discharge circuit, source electrode drive circuit and common electrode discharge method Download PDFInfo
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- CN109872698B CN109872698B CN201910296142.XA CN201910296142A CN109872698B CN 109872698 B CN109872698 B CN 109872698B CN 201910296142 A CN201910296142 A CN 201910296142A CN 109872698 B CN109872698 B CN 109872698B
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Abstract
The invention relates to a common electrode discharge circuit, a source electrode driving circuit and a common electrode discharge method. The common electrode discharge circuit includes: a comparator and a switching tube; the power supply Voltage (VDD) of source drive circuit is connected to the inverting input end of comparator, power supply voltage (VDD)'s threshold voltage (V1) when the in-phase input end of comparator connects the pixel electrode and begins to discharge after the predetermined power closes, the output of comparator is connected the control end of switch tube, the public electrode is connected to the first end of switch tube, the data signal line is connected to the second end of switch tube. The invention also provides a corresponding source electrode driving circuit and a common electrode discharging method. The invention specially designs a public electrode discharge circuit which can be integrated in the source electrode drive circuit and is used for discharging the public electrode and the pixel electrode simultaneously when the power supply is closed, thereby improving the screen flash phenomenon caused by the inconsistent discharge speed of the pixel electrode and the public electrode.
Description
Technical Field
The invention relates to the technical field of display, in particular to a common electrode discharge circuit, a source electrode driving circuit and a common electrode discharge method.
Background
In recent years, Liquid Crystal Display (LCD) devices have been widely used in many fields, and continue to show a rapid growth trend. With the improvement of driving technology, it has the advantages of low power consumption, thin and light weight, low voltage driving, etc., and has been widely applied to camcorders, notebook computers, desktop display devices and various projection apparatuses.
A liquid crystal display device generally includes a gate driver circuit, a source driver circuit, and a pixel array. The pixel array is provided with a plurality of pixel circuits, and each pixel circuit is turned on and off according to a scanning signal provided by the grid driving circuit and displays a data picture according to a data signal provided by the source driving circuit.
The pixel structure of the liquid crystal panel is generally composed of a pixel electrode, a common electrode (common electrode voltage VCOM), a Thin Film Transistor (TFT) connected to a data signal line and a gate signal line, and a liquid crystal capacitor and a storage capacitor. Under the control of a grid signal, the rotation angle of the liquid crystal molecules is controlled by electric fields formed by the pixel electrode and the common electrode which are respectively applied to the liquid crystal capacitor, and the display of a single liquid crystal pixel is realized. The storage capacitor is mainly used for keeping normal display of the previous line image within one frame time when the grid driving signal is scanned line by line.
In general, after the power is turned off, the liquid crystal display panel enters a discharge function, that is, the output (output) of the source Driver IC is pulled low, all the gate signal lines (gate lines) are pulled up to the high voltage VGH, so that the tft is turned on, and the pixel electrode is rapidly discharged. The common electrode discharges slowly because it has no special discharge circuit. A certain clamping pressure is formed between the pixel electrode and the common electrode, so that the liquid crystal is in a twisted state within a certain time after the power supply is turned off, and if the backlight is in an open state or light is irradiated to the surface of a liquid crystal box (cell) from the outside, a screen flash phenomenon can be seen.
Disclosure of Invention
Therefore, an object of the present invention is to provide a common electrode discharge circuit, a source driving circuit, and a common electrode discharge method, which can simultaneously discharge a common electrode and a pixel electrode when a power supply is turned off.
To achieve the above object, the present invention provides a common electrode discharge circuit including: a comparator and a switching tube; the power supply voltage of source drive circuit is connected to the inverting input end of comparator, power supply voltage's threshold voltage when the in-phase input end of comparator connects the pixel electrode and begins to discharge after the predetermined power closes, the output of comparator is connected the control end of switch tube, the public electrode is connected to the first end of switch tube, the second end of switch tube connects the data signal line.
The switch tube is a triode.
The triode is an NPN type triode.
The output end of the comparator is connected with the base electrode of the NPN type triode, the collector electrode of the NPN type triode is connected with the common electrode, and the emitter electrode of the NPN type triode is connected with the data signal wire.
The invention also provides a source electrode driving circuit, which comprises the common electrode discharge circuit.
The invention also provides a common electrode discharging method, which comprises the following steps:
step 10, when the power supply is turned off, the electric potential of the grid signal line is pulled high, the electric potential of the data signal line is pulled low, and the pixel electrode discharges through the data signal line; meanwhile, the power supply voltage of the source driving circuit begins to drop;
step 20, connecting the inverting input end of the comparator with the power supply voltage of the source electrode driving circuit, connecting the non-inverting input end of the comparator with the preset threshold voltage of the power supply voltage when the pixel electrode starts to discharge after the power supply is turned off, and connecting the output end of the comparator with the control end of the switching tube; when the comparator judges that the power supply voltage of the source electrode driving circuit is reduced to the threshold voltage, a control signal is output to control the switch tube to be opened;
and step 30, connecting a first end of the switch tube with a common electrode, connecting a second end of the switch tube with a data signal line, and discharging the common electrode through the data signal line when the switch tube is turned on.
The switch tube is a triode.
The triode is an NPN type triode.
The output end of the comparator is connected with the base electrode of the NPN type triode, the collector electrode of the NPN type triode is connected with the common electrode, and the emitter electrode of the NPN type triode is connected with the data signal wire.
In summary, the common electrode discharge circuit, the source driver circuit and the common electrode discharge method of the present invention specially design a common electrode discharge circuit, which can be integrated inside the source driver circuit, and is used for discharging the common electrode and the pixel electrode simultaneously when the power is turned off, thereby improving the screen flash phenomenon caused by the inconsistency of the discharge speed between the pixel electrode and the common electrode.
Drawings
The technical solution and other advantages of the present invention will become apparent from the following detailed description of specific embodiments of the present invention, which is to be read in connection with the accompanying drawings.
In the drawings, there is shown in the drawings,
FIG. 1 is a circuit diagram of a common electrode discharge circuit according to a preferred embodiment of the present invention;
FIG. 2 is a schematic diagram of an application of a source driver circuit according to a preferred embodiment of the invention.
Detailed Description
Referring to fig. 1, a circuit diagram of a common electrode discharge circuit according to a preferred embodiment of the invention is shown. The common electrode discharge circuit mainly includes: a comparator and NPN transistor T6; the negative phase input end of the comparator is connected with a power supply voltage VDD of the source electrode driving circuit, the positive phase input end of the comparator is connected with a threshold voltage V1 of the power supply voltage VDD when a preset power supply is turned off and a pixel electrode starts to discharge, the output end of the comparator is connected with a base electrode B of a triode T6, a collector electrode C of the triode T6 is connected with a common electrode, and an emitter electrode E of the triode T6 is connected with a data signal line. In other embodiments, the transistor T6 may be replaced by another type of switch tube, as will be understood by those skilled in the art.
Based on the circuit shown in fig. 1, the common electrode discharge method of the present invention can be implemented, and the method mainly includes:
step 10, when the power supply is turned off, the electric potential of the grid signal line is pulled high, the electric potential of the data signal line is pulled low, and the pixel electrode discharges through the data signal line; meanwhile, the power supply voltage VDD of the source driving circuit starts to decrease; this step is the conventional pixel electrode discharge process.
Step 20, connecting the inverting input end of the comparator with the power supply voltage VDD of the source electrode driving circuit, connecting the non-inverting input end of the comparator with a preset threshold voltage V1 of the power supply voltage VDD when the pixel electrode starts to discharge after the power supply is turned off, and connecting the output end of the comparator with the control end of the switching tube; when the comparator judges that the power supply voltage VDD of the source electrode driving circuit is reduced to a threshold voltage V1, a control signal is output to control the switch tube to be opened; in this step, the transistor T6 is used for switching the tube.
And step 30, connecting a first end of the switch tube with a common electrode, connecting a second end of the switch tube with a data signal line, and discharging the common electrode through the data signal line when the switch tube is turned on. When the switching tube specifically adopts the triode T6, as can be seen from the circuit shown in fig. 1, when VDD > V1, the base B of the triode T6 is at a low level, and the triode T6 is turned off; when VDD is less than V1, the base B of the triode T6 is at high level, the triode T6 is conducted, and at the moment, because the potential of the data signal line is pulled down, the common electrode discharges through the data signal line, thereby improving the screen flash phenomenon caused by the inconsistency of the discharge speed of the pixel electrode and the common electrode.
Referring to fig. 2, which is an application diagram of a preferred embodiment of the source driving circuit of the present invention, the source driving circuit of the present invention is applied to a conventional liquid crystal panel, and the source driving circuit may include the common electrode discharge circuit, and the common electrode discharge circuit is integrated inside the source driving circuit. As shown in fig. 2, the pixel structure of the liquid crystal panel is generally composed of a pixel electrode 1, a common electrode (not shown), a thin film transistor 2 connected to a data signal line and a gate signal line, and a liquid crystal capacitor (not shown) and a storage capacitor (not shown), and a source driver circuit is connected to the data signal line, and outputs a data signal to the liquid crystal panel through the data signal line during display. In the preferred embodiment, the common electrode discharge circuit (the specific structure can be shown in fig. 1) is integrated into the conventional source driver circuit.
For the liquid crystal panel using the source electrode driving circuit, when the power supply is turned off, the electric potential of the grid electrode signal wire is pulled high, the electric potential of the data signal wire is pulled low, and the pixel electrode discharges through the data signal wire; meanwhile, the power supply voltage VDD of the source driving circuit is reduced to be lower than the threshold voltage V1 of the pixel electrode for starting to discharge, and the common electrode can discharge through the data signal line through the common electrode discharge circuit embedded in the source driving circuit, so that the screen flash phenomenon caused by the fact that the discharge speed of the pixel electrode is different from that of the common electrode is improved.
In summary, the common electrode discharge circuit, the source driver circuit and the common electrode discharge method of the present invention specially design a common electrode discharge circuit, which can be integrated inside the source driver circuit, and is used for discharging the common electrode and the pixel electrode simultaneously when the power is turned off, thereby improving the screen flash phenomenon caused by the inconsistency of the discharge speed between the pixel electrode and the common electrode.
As described above, it will be apparent to those skilled in the art that various other changes and modifications can be made based on the technical solution and the technical idea of the present invention, and all such changes and modifications should fall within the protective scope of the appended claims.
Claims (9)
1. A common electrode discharge circuit, comprising: a comparator and a switching tube; the inverting input end of the comparator is connected with a power supply Voltage (VDD) of the source electrode driving circuit, the non-inverting input end of the comparator is connected with a preset threshold voltage (V1) of the power supply Voltage (VDD) when the pixel electrode starts to discharge after the power supply is turned off, the output end of the comparator is connected with the control end of the switch tube, the first end of the switch tube is connected with the common electrode, and the second end of the switch tube is connected with the data signal line;
the common electrode discharge circuit is integrated in the source electrode drive circuit.
2. The common electrode discharge circuit of claim 1, wherein said switching tube is a triode.
3. The common electrode discharge circuit of claim 2 wherein said transistor is an NPN transistor.
4. The common electrode discharge circuit of claim 3, wherein the output terminal of the comparator is connected to the base of the NPN transistor, the collector of the NPN transistor is connected to the common electrode, and the emitter of the NPN transistor is connected to the data signal line.
5. A source driving circuit comprising the common electrode discharge circuit according to any one of claims 1 to 4.
6. A common electrode discharge method applied to the common electrode discharge circuit according to claim 1, comprising:
step 10, when the power supply is turned off, the electric potential of the grid signal line is pulled high, the electric potential of the data signal line is pulled low, and the pixel electrode discharges through the data signal line; at the same time, the power supply Voltage (VDD) of the source driver circuit starts to fall;
step 20, connecting the inverting input end of the comparator with the power Voltage (VDD) of the source electrode driving circuit, connecting the non-inverting input end of the comparator with a preset threshold voltage (V1) of the power Voltage (VDD) when the pixel electrode starts to discharge after the power is turned off, and connecting the output end of the comparator with the control end of the switching tube; when the comparator judges that the power supply Voltage (VDD) of the source electrode driving circuit is reduced to a threshold voltage (V1), a control signal is output to control the switch tube to be opened;
and step 30, connecting a first end of the switch tube with a common electrode, connecting a second end of the switch tube with a data signal line, and discharging the common electrode through the data signal line when the switch tube is turned on.
7. The common electrode discharging method of claim 6, wherein the switching tube is a triode.
8. The common electrode discharging method of claim 7, wherein the transistor is an NPN transistor.
9. The common electrode discharging method according to claim 8, wherein an output terminal of the comparator is connected to a base of the NPN transistor, a collector of the NPN transistor is connected to the common electrode, and an emitter of the NPN transistor is connected to the data signal line.
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| CN109872698B true CN109872698B (en) | 2021-07-23 |
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| CN106710566A (en) * | 2017-03-31 | 2017-05-24 | 京东方科技集团股份有限公司 | Discharging circuit, driving method and display device thereof |
| CN106952628A (en) * | 2017-05-05 | 2017-07-14 | 惠科股份有限公司 | Ghost eliminating circuit and display device |
| CN108962165A (en) * | 2018-07-18 | 2018-12-07 | 南京熊猫电子制造有限公司 | A kind of circuit and method for eliminating IGZO display panel power down ghost |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4775850B2 (en) * | 2006-09-07 | 2011-09-21 | ルネサスエレクトロニクス株式会社 | Liquid crystal display device and drive circuit |
| CN104570417B (en) * | 2014-12-23 | 2019-05-28 | 上海天马微电子有限公司 | Liquid crystal display screen and electronic equipment |
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Patent Citations (6)
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| CN1924647A (en) * | 2005-08-30 | 2007-03-07 | 三星电子株式会社 | Liquid crystal display device, module for driving the same and method of driving the same |
| CN106558289A (en) * | 2015-09-30 | 2017-04-05 | 鸿富锦精密工业（深圳）有限公司 | Liquid crystal indicator and discharge control method |
| CN105679266A (en) * | 2016-03-11 | 2016-06-15 | 京东方科技集团股份有限公司 | Shutdown circuit, peripheral driving device and LCD panel |
| CN106710566A (en) * | 2017-03-31 | 2017-05-24 | 京东方科技集团股份有限公司 | Discharging circuit, driving method and display device thereof |
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Address after: 9-2 Tangming Avenue, Guangming New District, Shenzhen City, Guangdong Province Applicant after: TCL China Star Optoelectronics Technology Co.,Ltd. Address before: 9-2 Tangming Avenue, Guangming New District, Shenzhen City, Guangdong Province Applicant before: Shenzhen China Star Optoelectronics Technology Co.,Ltd. |
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