CN110706669A - Voltage compensation circuit - Google Patents
Voltage compensation circuit Download PDFInfo
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- CN110706669A CN110706669A CN201910884816.8A CN201910884816A CN110706669A CN 110706669 A CN110706669 A CN 110706669A CN 201910884816 A CN201910884816 A CN 201910884816A CN 110706669 A CN110706669 A CN 110706669A
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- 239000003990 capacitor Substances 0.000 claims abstract description 39
- 238000001914 filtration Methods 0.000 claims abstract description 25
- 239000004973 liquid crystal related substance Substances 0.000 claims abstract description 8
- 230000000694 effects Effects 0.000 abstract description 12
- 238000002955 isolation Methods 0.000 abstract description 3
- 238000000034 method Methods 0.000 description 6
- 230000008569 process Effects 0.000 description 6
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- 239000010949 copper Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Classifications
-
- 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
- G09G3/36—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 using liquid crystals
- G09G3/3611—Control of matrices with row and column drivers
- G09G3/3696—Generation of voltages supplied to electrode drivers
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (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)
Abstract
A voltage compensation circuit for compensating a VCOM voltage of a liquid crystal panel includes: one end of the input capacitor is used for being connected with the CFVCOM _ FB terminal; the first compensation unit is provided with a first connecting end used for connecting the other end of the input capacitor and a second connecting end connected with a VCOM end and used for controlling the compensation depth of the voltage at the CFVCOM _ FB end; the second compensation unit is provided with a first input end connected with the first connecting end of the first compensation unit and a second input end connected with the VCOM end and is used for compensating the voltage of the CF _ VCOM end; and the input end of the filtering output unit is connected with the output end of the second compensation unit, and the output end of the filtering output unit is connected with the CF _ VCOM end and used for filtering and outputting the compensated voltage. The invention realizes the isolation effect on the direct current voltage through the input capacitor. The first compensation unit controls the compensation depth of the voltage at the CFVCOM _ FB terminal, and the second compensation unit controls the voltage compensation. In addition, the stability of the output voltage is further improved by the filtering output unit.
Description
Technical Field
The invention belongs to the field of displays, and particularly relates to a voltage compensation circuit.
Background
With the development of liquid crystal display technology, people have higher and higher display effect on liquid crystal display panels. In order to achieve better display effect, the display effect of the panel is generally adjusted by adjusting the compensation factor of the reference Voltage (VCOM) for the liquid crystal molecule deflection. However, the liquid crystal molecules must be driven by an ac signal and maintain a certain polarity for a long time, and the liquid crystal molecules may be broken. Therefore, the VCOM electrode is used as the common electrode for the positive and negative inversion reference of the liquid crystal molecules, the voltage requirement is very accurate, and needs to be set at the middle value of the positive and negative inversion voltage, and if the set value is not uniform, the screen flicker can be caused.
Currently, the TFT circuit design generally includes an aluminum process and a copper process. The line loss of the aluminum process is large, the line loss of the copper process is small, and the difference of VCOM at the near end and the far end is large on an aluminum process or a large-size copper process screen, so that different areas of the screen flicker.
The terms: VCOM end is VCOM voltage connection port produced by GAMMA chip; the CF _ VCOM terminal is a near-end connection port for connecting VCOM voltage to a display screen line; the CFVCOM _ FB terminal is the far end connection port where the VCOM voltage is connected to the display screen lines.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a voltage compensation circuit which is simple in structure and eliminates the problem of flickering of different areas of a screen.
The voltage compensation circuit according to the embodiment of the invention comprises: one end of the input capacitor is used for being connected with the CFVCOM _ FB terminal; the first compensation unit is provided with a first connecting end used for connecting the other end of the input capacitor and a second connecting end connected with a VCOM end and used for compensating the voltage of the CF-VCOM end; a second compensation unit having a first input terminal connected to the first connection terminal of the first compensation unit, a second input terminal connected to the VCOM terminal, for compensating the CF _ VCOM terminal voltage; and the input end of the filtering output unit is connected with the output end of the second compensation unit, and the output end of the filtering output unit is connected with the CF _ VCOM end and used for outputting the compensated voltage.
The voltage compensation circuit according to the embodiment of the invention has at least the following technical effects: the isolation of the direct voltage is achieved by the input capacitance. The first compensation unit clamps the voltage of the CFVCOM-FB terminal, so that the control of the compensation depth of the voltage of the CFVCOM-FB terminal is realized, and then the second compensation unit realizes the compensation of the voltage. In addition, the compensation voltage is further filtered through the filtering output unit, and the stability of the output voltage is further improved.
According to some embodiments of the invention, the first compensation unit comprises: a first diode having an anode connected to the other end of the input capacitor and a cathode connected to the VCOM terminal; and the anode of the second diode is connected with the cathode of the first diode, and the cathode of the second diode is connected with the anode of the first diode.
According to some embodiments of the invention, the second compensation unit comprises: a first resistor having one end connected to the other end of the input capacitor; one end of the second resistor is connected with the other end of the first resistor, and the other end of the second resistor is connected with the input end of the filtering output unit; and a negative input pin of the operational amplifier unit is connected with the other end of the first resistor, a positive input pin of the operational amplifier unit is connected with the VCOM end, an output pin of the operational amplifier unit is connected with the input end of the filtering output unit, a ground pin of the operational amplifier unit is connected with a ground wire, and a working power supply pin of the operational amplifier unit is used for being connected with an external power supply.
According to some embodiments of the invention, the second compensation unit further comprises: the first capacitor is connected between a seventh pin of the operational amplifier unit and a ground wire; and the second capacitor is connected with the first capacitor in parallel.
According to some embodiments of the invention, the filtering output unit comprises; one end of the third resistor is connected with the output end of the second compensation unit; and the third capacitor is connected between the other end of the third resistor and the ground wire.
According to some embodiments of the invention, the voltage compensation circuit further comprises: a fourth resistor connected between the CF _ VCOM terminal and a ground line.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 is a circuit schematic of an embodiment of the invention.
Reference numerals:
a first compensation unit 100, a second compensation unit 200, and a filtering output unit 300.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In the description of the present invention, if there are first, second, third, fourth, etc. described only for the purpose of distinguishing technical features, they are not to be interpreted as indicating or implying relative importance or implying number of indicated technical features or implying precedence of indicated technical features.
In the description of the present invention, unless otherwise explicitly defined, terms such as arrangement, connection and the like should be broadly construed, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the detailed contents of the technical solutions.
A voltage compensation circuit according to an embodiment of the present invention is described below with reference to fig. 1.
The voltage compensation circuit according to the embodiment of the invention comprises: input capacitor C1, first compensation unit 100, second compensation unit 200, and filtering output unit 300.
An input capacitor C1, one end of which is connected to the CFVCOM _ FB terminal; a first compensation unit 100 having a first connection terminal for connecting the other end of the input capacitor C1, a second connection terminal for connecting the VCOM terminal, and a compensation depth for controlling the CFVCOM _ FB terminal voltage; a second compensation unit 200 having a first input terminal connected to the first connection terminal of the first compensation unit 100, a second input terminal connected to the VCOM terminal, for compensating the CF _ VCOM terminal voltage; and a filter output unit 300, an input end of which is connected to the output end of the second compensation unit 200, and an output end of which is connected to the CF _ VCOM end, for filtering and outputting the compensated voltage.
Referring to fig. 1, the input capacitor C1 is connected between the CFVCOM _ FB terminal and the first compensation unit 100, and serves to isolate a dc voltage component that may exist in the CFVCOM _ FB terminal. The first compensation unit 100 is connected after the input capacitor C1, and can control the compensation depth of the CFVCOM _ FB voltage to ensure that the input voltage fluctuation is not too large. The second compensation unit 200 functions as a compensation voltage by means of feedback, and outputs a processed voltage by using the voltage compensated by the first compensation unit 100 and the voltage at the VCOM terminal as input modes. The filter output unit 300 further filters the voltage output from the second compensation unit 200 and outputs the filtered voltage.
According to the voltage compensation circuit provided by the embodiment of the invention, the isolation effect on the direct current voltage is realized through the input capacitor C1. The voltage compensation is realized through the first compensation unit 100 and the second compensation unit 200, and compared with the conventional compensation mode, the compensation effect is more stable. In addition, the stability of the output voltage is further improved by further filtering by the filtering output unit 300.
In some embodiments of the present invention, referring to fig. 1, the first compensation unit 100 includes: a first diode D1, a second diode D2. The anode of the first diode D1 is connected with the other end of the input capacitor C1, and the cathode of the first diode D1 is connected with the VCOM end; the anode of the second diode D2 is connected to the cathode of the first diode D1, and the cathode is connected to the anode of the first diode D1. The CFVCOM _ FB terminal voltage input is processed by the input capacitor C1 and then connected to the first compensation unit 100, and when the CFVCOM _ FB terminal voltage is higher than the VCOM terminal voltage by a conducting voltage of the first diode D1, the first diode D1 is turned on, so that the effect of preventing the first input terminal voltage of the second compensation unit 200 from being higher than the VCOM terminal voltage plus a diode conducting voltage is finally achieved. Similarly, when the voltage at the VCOM terminal is higher than the voltage at the CFVCOM _ FB terminal by a turn-on voltage of the second diode D2, the second diode D2 is turned on, and the effect of preventing the voltage at the first input terminal of the second compensation unit 200 from being lower than the voltage at the VCOM terminal by a diode turn-on voltage is finally achieved. Finally, the first input end voltage of the second compensation unit 200 is kept in the range of the positive and negative diode conducting voltages of the VCOM end voltage, so that the problem of abnormal CF _ VCOM end voltage output caused by overlarge CFVCOM _ FB voltage fluctuation can be effectively prevented.
In some embodiments of the present invention, referring to fig. 1, the second compensation unit 200 includes: the circuit comprises a first resistor R1, a second resistor R2 and an operational amplifier unit U1. A first resistor R1, one end of which is connected to the other end of the input capacitor C1; a second resistor R2, one end of which is connected to the other end of the first resistor R1, and the other end of which is connected to the input end of the filter output unit 300; and a negative input pin of the operational amplifier unit is connected with the other end of the first resistor, a positive input pin of the operational amplifier unit is connected with the VCOM end, an output pin of the operational amplifier unit is connected with the input end of the filtering output unit 300, a ground pin of the operational amplifier unit is connected with a ground wire, and a working power supply pin of the operational amplifier unit is used for being connected with an external power supply AVDD. The first resistor R1, the second resistor R2 and the operational amplifier form a differential subtractor with negative feedback, the VCOM terminal voltage is set as Ui2, the negative input pin input voltage of the operational amplifier unit U1 is Ui1, the output pin output voltage of the operational amplifier unit U1 is Uo, and then Uo is Ui2+ (Ui2-Ui1) (R2/R1); the ratio of R2 to R1 can be adjusted, the specific ratio needs to be debugged according to an actual test picture, and the main mode is as follows: when the screen load changes greatly, the ratio is adjusted to enable the screen to achieve the effect of no flicker. When the second compensation unit 200 finishes the adjustment and enters the actual working state, the output voltage is adjusted by a differential subtracter with negative feedback according to the voltage input by the negative input pin of the operational amplifier unit U1 and the VCOM terminal voltage of the positive input pin. In addition, the first resistor R1 and the input capacitor C1 form a differential circuit, which plays a better role in blocking the dc voltage.
In some embodiments of the present invention, referring to fig. 1, the second compensation unit 200 further includes: a first capacitor C2 and a second capacitor C3. The first capacitor C2 is connected between the working power supply pin of the operational amplifier unit U1 and the ground wire; and the second capacitor C3 is connected with the first capacitor C2 in parallel. The first capacitor C2 and the second capacitor C3 are mainly used for filtering, and are used for ensuring the stability of the operation of the operational amplifier unit U1.
In some embodiments of the present invention, referring to fig. 1, the filtering output unit 300 includes; a third resistor R3 and a third capacitor C4. A third resistor R3 having one end connected to the output end of the second compensation unit 200; and a third capacitor C4 connected between the other end of the third resistor R3 and ground. The third resistor R3 and the third capacitor C4 form a filter circuit, so that a good filtering effect can be achieved, the stability of output voltage is further guaranteed, and the auxiliary screen flash lightening effect is achieved.
In some embodiments of the present invention, referring to fig. 1, further comprising a fourth resistor connected between the CF _ VCOM terminal and the ground line. The fourth resistor is used as a discharge resistor and can play a role in discharging the screen end when the power is off.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
Although the embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to the embodiments, and those skilled in the art will understand that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims (6)
1. A voltage compensation circuit for compensating a VCOM voltage of a liquid crystal panel, comprising:
one end of the input capacitor is used for being connected with the CFVCOM _ FB terminal;
the first compensation unit (100) is provided with a first connecting end used for connecting the other end of the input capacitor and a second connecting end connected with a VCOM end and used for controlling the compensation depth of the voltage at the CFVCOM _ FB end;
a second compensation unit (200) having a first input terminal connected to the first connection terminal of the first compensation unit (100), a second input terminal connected to the VCOM terminal, for compensating a CF _ VCOM terminal voltage;
and the input end of the filtering output unit (300) is connected with the output end of the second compensation unit (200), and the output end of the filtering output unit is connected with the CF _ VCOM end, and the filtering output unit is used for filtering and outputting the compensated voltage.
2. A voltage compensation circuit according to claim 1, wherein the first compensation unit (100) comprises:
a first diode having an anode connected to the other end of the input capacitor and a cathode connected to the VCOM terminal;
and the anode of the second diode is connected with the cathode of the first diode, and the cathode of the second diode is connected with the anode of the first diode.
3. A voltage compensation circuit according to claim 1, wherein the second compensation unit (200) comprises:
a first resistor having one end connected to the other end of the input capacitor;
one end of the second resistor is connected with the other end of the first resistor, and the other end of the second resistor is connected with the input end of the filtering output unit (300);
and a negative input pin of the operational amplifier unit is connected with the other end of the first resistor, a positive input pin of the operational amplifier unit is connected with the VCOM end, an output pin of the operational amplifier unit is connected with the input end of the filtering output unit (300), a ground pin of the operational amplifier unit is connected with a ground wire, and a working power supply pin of the operational amplifier unit is used for being connected with an external power supply.
4. A voltage compensation circuit according to claim 3, wherein the second compensation unit (200) further comprises:
the first capacitor is connected between the seventh pin of the operational amplifier unit and the ground wire;
and the second capacitor is connected with the first capacitor in parallel.
5. A voltage compensation circuit according to claim 1, wherein the filter output unit (300) comprises;
a third resistor, one end of which is connected with the output end of the second compensation unit (200);
and the third capacitor is connected between the other end of the third resistor and the ground wire.
6. The voltage compensation circuit of claim 1, further comprising: a fourth resistor connected between the CF _ VCOM terminal and a ground line.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910884816.8A CN110706669A (en) | 2019-09-19 | 2019-09-19 | Voltage compensation circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910884816.8A CN110706669A (en) | 2019-09-19 | 2019-09-19 | Voltage compensation circuit |
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| CN110706669A true CN110706669A (en) | 2020-01-17 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910884816.8A Pending CN110706669A (en) | 2019-09-19 | 2019-09-19 | Voltage compensation circuit |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1195785A (en) * | 1997-02-07 | 1998-10-14 | 株式会社日立制作所 | Liquid crystal display having voltage compensating function |
| CN1635403A (en) * | 2003-12-25 | 2005-07-06 | 联想(北京)有限公司 | Method and apparatus for eliminating LCD frame flicker phenomenon |
| CN106297709A (en) * | 2016-09-09 | 2017-01-04 | 合肥鑫晟光电科技有限公司 | Display floater, compensation device, display device and common electrode voltage compensation method |
| CN108172190A (en) * | 2018-01-15 | 2018-06-15 | 深圳市华星光电技术有限公司 | For the amplifying circuit of liquid crystal display |
| CN210722412U (en) * | 2019-09-19 | 2020-06-09 | 广东长虹电子有限公司 | Voltage compensation circuit |
-
2019
- 2019-09-19 CN CN201910884816.8A patent/CN110706669A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1195785A (en) * | 1997-02-07 | 1998-10-14 | 株式会社日立制作所 | Liquid crystal display having voltage compensating function |
| CN1635403A (en) * | 2003-12-25 | 2005-07-06 | 联想(北京)有限公司 | Method and apparatus for eliminating LCD frame flicker phenomenon |
| CN106297709A (en) * | 2016-09-09 | 2017-01-04 | 合肥鑫晟光电科技有限公司 | Display floater, compensation device, display device and common electrode voltage compensation method |
| CN108172190A (en) * | 2018-01-15 | 2018-06-15 | 深圳市华星光电技术有限公司 | For the amplifying circuit of liquid crystal display |
| CN210722412U (en) * | 2019-09-19 | 2020-06-09 | 广东长虹电子有限公司 | Voltage compensation circuit |
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