Pixel circuit, display device and driving method

Patent metadata

Field	Value
Publication number	US-11081040-B2
Application number	US-201816308437-A
Country	US
Kind code	B2
Filing date	Apr 19, 2018
Priority date	Jun 23, 2017
Publication date	Aug 3, 2021
Grant date	Aug 3, 2021

Abstract

A pixel circuit includes a liquid crystal capacitor, a selection unit, a gray scale writing unit, and a reset unit. The selection unit is configured to determine whether to charge the liquid crystal capacitor according to a row control signal and a column control signal. The gray scale writing unit is configured to apply a gray scale voltage signal to the liquid crystal capacitor, when the selection unit determines to charge the liquid crystal capacitor, and an application duration of the gray scale voltage signal controls a gray scale level displayed by the liquid crystal capacitor. The reset unit is configured to disconnect the gray scale writing unit and the liquid crystal capacitor to stop charging the liquid crystal capacitor upon receiving the reset signal, and reset the voltage of the liquid crystal capacitor to an initial state.

First claim

What is claimed is:

1. A pixel circuit, comprising:
a liquid crystal capacitor having a first end and a second end;
a selection unit having a first end, a second end, and an output end, wherein the first end of the selection unit is configured to receive a column control signal, the second end of the selection unit is configured to receive a row control signal, and the selection unit is configured to determine whether to charge the liquid crystal capacitor according to the row control signal and the column control signal;
a gray scale writing unit having a first end, a second end, and an output end, wherein the first end of the gray scale writing unit is connected to the output end of the selection unit, and the second end of the gray scale writing unit is connected to a gray scale voltage signal, the output end of the gray scale writing unit is connected to the second end of the liquid crystal capacitor, and the gray scale writing unit is configured to, when the selection unit determines to charge the liquid crystal capacitor, apply the gray scale voltage signal to the liquid crystal capacitor, and a gray scale level displayed by the liquid crystal capacitor is controlled by an application duration of the gray scale voltage signal; and
a reset unit having a first end, a second end, a third end, and a fourth end, wherein the first end of the reset unit is connected to a reset signal end, the second end of the reset unit is connected to the output end of the selection unit, and the third end of the reset unit is connected to the output end of the gray scale writing unit, the fourth end of the reset unit is connected to a common voltage signal, and the reset unit is configured to disconnect the gray scale writing unit and the liquid crystal capacitor to stop charging the liquid crystal capacitor upon receiving the reset signal end, and reset voltage of the liquid crystal capacitor to an initial state.

2. The pixel circuit according to claim 1 , the selection unit comprises:
a first transistor having a first end, a second end and a control end,
a second transistor each having a first end, a second end and a control end,
wherein the control end of the first transistor is connected to the column control signal, and the first end of the first transistor is connected to the row control signal, the second end of the first transistor is connected to the first end of the second transistor, and the control end of the second transistor is connected to the row control signal.

3. The pixel circuit according to claim 2 , wherein the gray scale writing unit comprises a third transistor having a first end, a second end and the control end, wherein the control end of the third transistor is connected to the second end of the second transistor, the first end of the third transistor is connected to the gray scale voltage signal, and the second end of the third transistor is connected to the second end of the liquid crystal capacitor.

4. The pixel circuit according to claim 3 , the reset unit comprises:
a fourth transistor, a fifth transistor, and a storage capacitor, wherein each of the fourth transistor and the fifth transistor has the first end, the second end and the control end, the storage capacitor has the first end and the second end, the control ends of the fourth transistor and the fifth transistor are both connected to the reset signal end, and the first ends of the fourth transistor, the fifth transistor and the storage capacitor are all connected to the second end of the second transistor, the second end of the fourth transistor is connected to the common voltage signal, and the second end of the fifth transistor and the storage capacitor is connected to the first end of the liquid crystal capacitor, and the second end of the liquid crystal capacitor is connected to the common voltage signal.

5. A display device, comprising:
a display panel having a plurality of pixel circuits according to claim 1 arranged in an array;
a timing controller configured to determine the gray scale level to display in each of the plurality of the pixel circuits in the display panel according to information of a to-be-displayed image, and cause a liquid crystal capacitor in each of the plurality of the pixel circuits to display the gray scale level by controlling a charging duration of the liquid crystal capacitor in each of the plurality of pixel circuits.

6. The display device according to claim 5 , the timing controller comprises:
a gray scale control unit configured to sequentially apply a plurality of gray scale voltage signals to the liquid crystal capacitors in the plurality of pixel circuits according to the gray scale level; and
a charging control unit configured to simultaneously stop applying the plurality of gray scale voltage signals to the liquid crystal capacitors in the plurality of pixel circuits in the display panel to control the charging duration of the liquid crystal capacitor in each of the plurality of pixel circuits.

7. The display device according to claim 6 , wherein the gray scale control unit is configured to:
determine location information of the charging duration pixel circuits corresponding to a first gray scale level in the display panel;
generate corresponding row control signals and column control signals according to the location information;
apply the plurality of gray scale voltage signals to the liquid crystal capacitors in the plurality of pixel circuits corresponding to the first gray scale level row by row according to the row control signals and the column control signals; and
apply the plurality of gray scale voltage signals to the liquid crystal capacitors in the plurality of pixel circuits corresponding to a second gray scale level after applying the gray scale voltage signals to all the liquid crystal capacitors corresponding to the first gray scale levels, until the gray scale voltage signals are applied to the liquid crystal capacitors in all the pixel circuits corresponding to a first level of a last gray scale level.

8. A driving method for a pixel circuit, the pixel circuit comprising:
a liquid crystal capacitor having a first end and a second end;
a selection unit having a first end, a second end, and an output end, wherein the first end of the selection unit is configured to receive a column control signal, the second end of the selection unit is configured to receive a row control signal, and the selection unit is configured to determine whether to charge the liquid crystal capacitor according to the row control signal and the column control signal;
a gray scale writing unit having a first end, a second end, and an output end, wherein the first end of the gray scale writing unit is connected to the output end of the selection unit, and the second end of the gray scale writing unit is connected to a gray scale voltage signal, the output end of the gray scale writing unit is connected to the second end of the liquid crystal capacitor, and the gray scale writing unit is configured to, when the selection unit determines to charge the liquid crystal capacitor, apply the gray scale voltage signal to the liquid crystal capacitor, and a gray scale level displayed by the liquid crystal capacitor is controlled by an application duration of the gray scale voltage signal control; and
a reset unit having a first end, a second end, a third end, and a fourth end, wherein the first end of the reset unit is connected to a reset signal end, the second end of the reset unit is connected to the output end of the selection unit, and the third end of the reset unit is connected to the output end of the gray scale writing unit, the fourth end of the reset unit is connected to a common voltage signal, and the reset unit is configured to disconnect

Assignees

• Beijing Boe Display Tech Co
• Boe Technology Group Co Ltd

Inventors

• Chen Pengming
• Zhang Bin
• Dong Dianzheng
• Zhang Qiang
• Wang Guangxing
• Zhang Kan
• Xu Wenpeng
• Guo Ziqiang
• Lu Yongquan

Classifications

• G09G3/3648 Primary

  using an active matrix (G09G3/367 - G09G3/3696 take precedence) · CPC title

• G09G2310/0251

  Precharge or discharge of pixel before applying new pixel voltage · CPC title

• G09G3/2007 Primary

  Display of intermediate tones · CPC title

• G09G2310/0248

  Precharge or discharge of column electrodes before or after applying exact column voltages · CPC title

• G09G2300/0819

  used for counteracting undesired variations, e.g. feedback or autozeroing · CPC title