CN104700800B - Gamma voltage generation circuit and gamma voltage generation method - Google Patents

Abstract

The present disclosure provides a gamma voltage generating circuit and method, which are suitable for a display panel capable of displaying at least one image during a blank period and a display period. The gamma voltage generating circuit includes a plurality of transistors, a plurality of resistors and a switch unit. A part of the transistor is used to be connected in series with the electrical group. The switch unit turns off a part of the transistor during the blank period and turns on another part of the transistor according to the received control signal. The other part of the transistor is used to receive the preset gray-scale voltage. When the other part of the transistor is turned on, the preset gray-scale voltage will be transmitted to the electrical group through the other part of the transistor. series connection points to output the preset gray-scale voltage through these series connection points.

Description

Gamma voltage generating circuit and gamma voltage generating method

technical field

The invention relates to a gamma voltage generation circuit, in particular to a gamma voltage generation circuit and method capable of generating a specific gamma voltage value during a blank period of a display screen.

Background technique

Nowadays, smart devices are becoming more and more inseparable from our lives, such as smart phones and tablet computers are becoming more and more popular. In order to obtain a better viewing effect, various display panel manufacturers are devoting themselves to improving the viewing angle of the display panel, so a wide viewing angle display panel is born.

In wide viewing angle display panels, there is a problem of common voltage (Vcom) drift, which is caused by charge accumulation on the electrodes used to control the deflection of the liquid crystal layer in the display panel, and the drift of common voltage will cause display Unexpected screen flicker (flicker) occurs when the panel displays the screen. Generally speaking, in order to solve the above problems, it is usually used to release the charges accumulated on the electrodes on both sides of the liquid crystal layer when the display is turned off, so as to improve the drift problem of the common voltage and avoid the flickering of the display screen. However, this solution The effect of the released charge is limited.

Contents of the invention

The invention provides a gamma voltage generation circuit, which can improve the problem of common voltage drift when the display is turned on, and avoid the flickering of the display screen.

The present invention further provides a gamma voltage generation method suitable for the above-mentioned gamma voltage generation circuit.

A gamma voltage generating circuit proposed by the present invention is suitable for a display panel, and the display panel is used to display at least one picture, and the picture includes a blank period and a display period. The gamma voltage generation circuit includes a first transistor, a second transistor, multiple third transistors, multiple resistors and a switch unit. The first transistor has a control terminal, a first terminal and a second terminal, and the first terminal of the first transistor is electrically connected to an operating voltage. The second transistor has a control terminal, a first terminal and a second terminal, and the second terminal of the second transistor is electrically connected to a reference voltage. The resistors are connected in series between the second terminal of the first transistor and the first terminal of the second transistor, and each resistor and its adjacent resistors are connected in series through a series connection point. Each third transistor has a control terminal, a first terminal and a second terminal, the first terminal of the third transistor is electrically connected to a preset gray-scale voltage, the voltage value of the preset gray-scale voltage Between the working voltage and the reference voltage, and the second ends of the third transistors are electrically connected to the corresponding serial connection points. The switch unit is electrically connected to the control terminal of the first transistor, the control terminal of the second transistor and the control terminal of the third transistor. The switch unit is used for receiving a control signal, and turning off the first transistor and the second transistor during the blank period according to the received control signal, and turning off the first transistor and the second transistor during the blank period according to the received control signal. Turn on the third transistor. The switch unit turns on the first transistor and the second transistor during the display period according to the received control signal, and turns off the third transistor during the display period according to the received control signal. When the third transistor is turned on, the preset grayscale voltage is transmitted to the cascade connection point to output the preset grayscale voltage through the cascade connection point.

The present invention also proposes a gamma voltage generating method, which is suitable for a gamma voltage generating circuit in a display panel. The display panel is used to display at least one frame, and the frame includes a blank period and a display period. The gamma voltage generation circuit includes a first transistor, a second transistor, multiple third transistors, multiple resistors and a switch unit. The first transistor receives an operating voltage, the second transistor receives a reference voltage, the resistor is connected in series between the first transistor and the second transistor and has a plurality of series connection points, the third The transistor receives a preset gray scale voltage, the switch unit is electrically connected to the first transistor, the second transistor and the third transistor and determines whether to turn on the third transistor to set the gray scale The voltage is output to the series connection point through the third transistor. The gamma voltage generation method includes the following steps: providing a control signal to the switch unit. Wherein, the switch unit turns off the first transistor and the second transistor according to the control signal during the blank period, and turns on the first transistor according to the control signal during the blank period. Three transistors. Wherein, the switch unit turns on the first transistor and the second transistor according to the control signal during the display period, and turns off the first transistor according to the control signal during the display period. Three transistors.

In the present invention, the switch unit is turned off the first transistor and the second transistor according to the control signal during the blank period of the display panel, and the switch unit is turned on a plurality of third transistors according to the control signal during the same blank period, so that The third transistor outputs the received preset gray scale voltage through the serial connection point between the multiple resistors, so that the drifting common voltage can be improved and the flickering of the display screen can be avoided while the display panel is still in operation.

Description of drawings

1 is a circuit diagram of a gamma voltage generating circuit according to an embodiment of the present invention;

FIG. 2 is a timing diagram of a gamma voltage generating circuit according to an embodiment of the present invention;

FIG. 3 is a timing diagram of a gamma voltage generating circuit according to another embodiment of the present invention;

FIG. 4 is a timing diagram of a gamma voltage generating circuit according to yet another embodiment of the present invention;

FIG. 5 is a flowchart of a gamma voltage generation circuit generating gamma voltages according to an embodiment of the present invention.

Explanation of reference signs:

11, 12, 13: Transistors

11-1, 12-1, 13-1: First end

11-2, 12-2, 13-2: Second end

11-3, 12-3, 13-3: Control terminal

14: Resistance

15: switch unit

AVDD: working voltage

GND: reference voltage

S: serial point

HAOP: preset grayscale voltage

V _BK : Control signal

DS: data signal

B, B1, B2, B3, B4: blank period

A, A1, A2, A3, A4: During display

F, F1, F2, F3, F4: screen

501: Steps

detailed description

FIG. 1 is a circuit diagram of a gamma voltage generating circuit according to an embodiment of the present invention. As shown in FIG. 1 , the gamma voltage generating circuit 100 includes a transistor 11 , a transistor 12 , a plurality of transistors 13 connected in series, a plurality of resistors 14 connected in series and a switch unit 15 . The transistor 11 has a first terminal 11-1, a second terminal 11-2 and a control terminal 11-3. The first end 11 - 1 of the transistor 11 is electrically connected to the operating voltage AVDD. The transistor 12 has a first terminal 12-1, a second terminal 12-2 and a control terminal 12-3. The second terminal 12-2 of the transistor 12 is electrically connected to the reference voltage GND. In this embodiment, the reference voltage GND is, for example, ground, but it is not limited thereto. The resistors 14 are connected in series between the second terminal 11 - 2 of the transistor 11 and the first terminal 12 - 1 of the transistor 12 , and each resistor 14 and its adjacent resistors 14 are connected in series through a series connection point S. In this embodiment, the voltage difference between the working voltage AVDD and the reference voltage GND is divided by the series connected resistors 14 so that each series connection point S can output different gamma voltages. Each transistor 13 has a first terminal 13-1, a second terminal 13-2 and a control terminal 13-3. The first terminal 13-1 of the transistor 13 is electrically connected to the preset gray scale voltage HAOP, the voltage value of the preset gray scale voltage HAOP is between the operating voltage AVDD and the reference voltage GND, and the second terminal 13-1 of the transistor 13- 2 are each electrically connected to the corresponding series connection point S. In this embodiment, the number of transistors 13 is equal to the number of resistors 14 , and the voltage value of the preset gray scale voltage HAOP is equal to the average value of the operating voltage AVDD and the reference voltage GND, but the present invention is not limited thereto. The switch unit 15 is electrically connected to the control terminal 11 - 3 of the transistor 11 , the control terminal 12 - 3 of the transistor 12 and the control terminal 13 - 3 of the transistor 13 . In addition, the gamma voltage generating circuit 100 shown in FIG. 1 is suitable for a display panel (not shown), which is used to display at least one frame, and the frame includes a blank period and a display period.

FIG. 2 is a timing diagram of a gamma voltage generating circuit according to an embodiment of the present invention. As shown in FIG. 2 , the data signal DS represents a signal provided to a data line (not shown) of the display panel when the display panel (not shown) displays a frame, that is, a frame. The aforementioned frame, that is, a period of the data signal DS, includes a blank period B and a display period A in this period. In particular, when the display panel displays a blank period B of a picture, what the data line receives is a low-level data signal DS. At this time, the series connection point S does not output the Gamma voltage substantially, and when the display panel During the display period A of displaying a frame, the data line receives a high-level data signal DS, and at this time, the cascading point S outputs a gamma voltage to make the display panel display a specific grayscale frame.

Please refer to FIG. 1 and FIG. 2 together. The switch unit 15 is used to receive the control signal V _BK , and turn off the transistor 11 and the transistor 12 during the blank period B according to the received control signal V _BK , and according to the received control signal V _BK In the blank period B, the transistor 13 is turned on. The switch unit 15 also turns on the transistor 11 and the transistor 12 during the display period A according to the received control signal V _BK , and turns off the transistor 13 during the display period A according to the received control signal V _BK . When the transistor 13 is turned on, the predetermined grayscale voltage HAOP is transmitted to the series connection point S to output the predetermined grayscale voltage HAOP through the series connection point S. In detail, the transistor 11 and the transistor 12 in the gamma voltage generating circuit 100 are cut off by the switch unit 15 according to the high-level control signal V _BK during the blank period B when the display panel displays a picture, so the working voltage AVDD and the reference voltage There is no conduction path between GND, and at this time the switching system 15 also turns on the transistor 13 according to the high-level control signal V _BK , so the preset gray scale voltage HAOP will be output to the corresponding string through the transistor 13 Contact S. Through the above operations, each series connection point S in the gamma voltage generating circuit 100 can output the preset gray-scale voltage HAOP during the blank period B when the display panel displays a picture, so that the full picture becomes a light-load picture during the blank period, which can be achieved. Accelerates the release of residual charge in the liquid crystal, thereby improving the problems of image retention and flickering of the display panel.

FIG. 3 is a timing diagram of a gamma voltage generating circuit according to another embodiment of the present invention. The same reference numerals in FIG. 3 and FIG. 2 represent the same elements or signals. As shown in Figure 3, when the display panel displays multiple screens F1-F4, for example, F1 is represented as the first screen, F2 is represented as the second screen, F3 is represented as the third screen, and F4 is represented as the fourth screen. In the picture, the switch unit 15 turns off the transistors 11 and 12 in each blank period B1-B4 according to the received control signal V _BK , and turns on the transistors in each blank period B1-B4 according to the received control signal V _BK 13, so that the gamma voltage generating circuit 100 outputs the preset gray scale voltage HAOP through each cascade connection point during the blank periods B1-B4 of the display panel. The switch unit 15 also turns on the transistor 11 and the transistor 12 during each display period A1-A4 according to the received control signal V _BK , and turns off the transistor 13 during each display period A1-A4 according to the received control signal V _BK . , so that the gamma voltage generating circuit 100 outputs the gamma voltage required for displaying images during each display period A1 - A4 of the display panel.

FIG. 4 is a timing diagram of a gamma voltage generating circuit according to another embodiment of the present invention. The same reference numerals in FIG. 4 and FIG. 2 represent the same elements or signals. As shown in FIG. 4, when the display panel displays multiple frames, the switch unit 15 turns off the transistors 11 and 12 during at least one blank period B1-B4 of the non-adjacent frames according to the received control signal V _BK , and According to the received control signal V _BK , the transistor 13 is turned on during at least one blank period B1-B4 of the non-adjacent frames, so that the gamma voltage generating circuit 100 passes through each of the at least one blank period B1-B4 of the display panel. The series connection point S outputs the preset gray scale voltage HAOP. In this embodiment, the switch unit 15 is for example to turn off the transistor 11 and the transistor 12 and turn on the transistor 13 during the blank periods B1 and B3 of the first frame F1 and the third frame F3 according to the received control signal V _BK , So that the gamma voltage generating circuit 100 outputs the preset grayscale voltage HAOP through the corresponding serial connection point S during the blank periods B1 and B3 when the display panel displays the first frame F1 and the third frame F3 . The switch unit 15 turns on the transistor 11 and the transistor 12 during each display period A1-A4 according to the received control signal V _BK , and turns off the transistor 13 during each display period A1-A4 according to the received control signal V _BK , So that the gamma voltage generating circuit 100 outputs the gamma voltage required for displaying the picture through the corresponding serial connection point S during each display period A1 - A4 of the display panel.

In particular, the duration of the control signal V _BK mentioned in the present invention is equal to the duration of the blank period B, but the present invention is not limited thereto, and the duration of the control signal V _BK can be seen Adjusted as needed, but not exceeding the duration of blank period B.

FIG. 5 is a flowchart of a gamma voltage generation circuit generating gamma voltages according to an embodiment of the present invention. As shown in FIG. 5 , the above-mentioned method of generating the gamma voltage by the gamma voltage generating circuit 100 , that is, outputting the preset gray scale voltage HAOP, can be summarized into a main step 501 : providing a control signal to the switch unit. Since the timing of providing the control signal and the operation of the switch unit after receiving the control signal have already been described above, they will not be repeated here.

To sum up, the gamma voltage generating circuit 100 of the present invention adopts a transistor 11, a transistor 12, a plurality of transistors 13, a plurality of resistors 14 and a switch unit 15, and receives a control signal through the switch unit 15 to display a blank In the period B, the transistor 11 and the transistor 12 are turned off to stop outputting the normal gamma voltage during this period, and the transistor 13 is turned on during this period so that the preset grayscale voltage HAOP is transmitted to the corresponding serial connection point S through the transistor 13 so that The gamma voltage generating circuit 100 outputs the preset grayscale voltage HAOP, so that the full screen can be light-loaded during the blank period, and can accelerate the release of residual charges in the liquid crystal to avoid flickering of the display screen.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the present invention The scope of protection shall prevail as defined by the appended claims.

Claims (8)

1. A gamma voltage generation circuit, suitable for a display panel, the display panel is used to display at least one frame, the frame includes a blank period and a display period, the gamma voltage generation circuit includes: A first transistor has a control terminal, a first terminal and a second terminal, the first terminal of the first transistor is electrically connected to an operating voltage; a second transistor having a control terminal, a first terminal and a second terminal, the second terminal of the second transistor is electrically connected to a reference voltage; A plurality of resistors, the plurality of resistors are connected in series between the second terminal of the first transistor and the first terminal of the second transistor, each resistor has a serial connection point between its adjacent resistors; A plurality of third transistors, each third transistor has a control terminal, a first terminal and a second terminal, the first terminals of the multiple third transistors are electrically connected to a preset gray scale voltage, the preset It is assumed that the voltage value of the gray scale voltage is between the operating voltage and the reference voltage, and the second terminals of the plurality of third transistors are respectively electrically connected to the corresponding series connection points; and A switch unit, the switch unit is electrically connected to the control terminal of the first transistor, the control terminal of the second transistor and the control terminals of the plurality of third transistors, the switch unit is used to receive a control signal ; Wherein, the switch unit turns off the first transistor and the second transistor during the blank period according to the received control signal, and turns on the plurality of third transistors during the blank period according to the received control signal, The switch unit turns on the first transistor and the second transistor during the display period according to the received control signal, and turns off the plurality of third transistors during the display period according to the received control signal; Wherein, when the plurality of third transistors are turned on, the preset grayscale voltage will be transmitted to the series connection point to output the preset grayscale voltage through the series connection point. 2. The gamma voltage generating circuit as claimed in claim 1, wherein a voltage value of the preset gray scale voltage is equal to an average value of the operating voltage and the reference voltage. 3. The gamma voltage generation circuit as claimed in claim 1, wherein when the display panel displays multiple images, the switch unit turns off the first transistor and the first transistor in each blank period according to the received control signal the second transistor, and turn on the plurality of third transistors in each blank period according to the received control signal; the switch unit turns on the first transistor and the third transistor in each display period according to the received control signal The second transistor and the plurality of third transistors are turned off during each display period according to the received control signal. 4. The gamma voltage generating circuit as claimed in claim 1, wherein when the display panel displays a plurality of frames, the switch unit turns off the switch unit in at least one blank period of non-adjacent frames according to the received control signal. The first transistor, the second transistor, and the plurality of third transistors are turned on during at least one blank period of the non-adjacent frames according to the received control signal, and the switch unit is switched according to the received control signal. The first transistor and the second transistor are turned on during each display period, and the plurality of third transistors are turned off during each display period according to the received control signal. 5. The gamma voltage generating circuit as claimed in claim 1, wherein the number of the third transistors is equal to the number of the resistors. 6. A gamma voltage generating method, suitable for a gamma voltage generating circuit in a display panel, the display panel is used to display at least one picture, the picture includes a blank period and a display period, the gamma voltage is generated The circuit includes a first transistor, a second transistor, multiple third transistors, multiple resistors and a switch unit, the first transistor receives an operating voltage, the second transistor receives a reference voltage, and the multiple resistors are connected in series Between the first transistor and the second transistor there are multiple series connection points, the multiple third transistors receive a preset gray scale voltage, the switch unit is electrically connected to the first transistor, the second transistor and The multiple third transistors determine whether to turn on the multiple third transistors so as to output the grayscale voltage to the series connection point through the multiple third transistors. The gamma voltage generation method includes: providing a control signal to the switch unit; Wherein, the switch unit turns off the first transistor and the second transistor according to the control signal during the blank period, and turns on the plurality of third transistors according to the control signal during the blank period; Wherein, the switch unit turns on the first transistor and the second transistor according to the control signal during the display period, and turns off the plurality of third transistors according to the control signal during the display period. 7. The gamma voltage generating method according to claim 6, wherein when the display panel displays multiple images, the switch unit turns off the first transistor and the first transistor in each blank period according to the received control signal the second transistor, and turn on the plurality of third transistors in each blank period according to the received control signal; the switch unit turns on the first transistor and the third transistor in each display period according to the received control signal The second transistor and the plurality of third transistors are turned off during each display period according to the received control signal. 8. The gamma voltage generation method according to claim 6, wherein when the display panel displays a plurality of frames, the switch unit turns off the switch unit in at least one blank period of non-adjacent frames according to the received control signal. The first transistor, the second transistor, and the plurality of third transistors are turned on during at least one blank period of the non-adjacent frames according to the received control signal, and the switch unit is switched according to the received control signal. The first transistor and the second transistor are turned on during each display period, and the plurality of third transistors are turned off during each display period according to the received control signal.