Scan driving circuit having pull-up control assembly and LCD device

Patent metadata

Field	Value
Publication number	US-9595234-B2
Application number	US-201414411106-A
Country	US
Kind code	B2
Filing date	Jun 25, 2014
Priority date	May 20, 2014
Publication date	Mar 14, 2017
Grant date	Mar 14, 2017

Abstract

A scan driving circuit includes a pull-up assembly, a pull-up control assembly that drives the pull-up assembly, a pull-down maintaining assembly, and a reference low-level signal. The reference low-level signal includes a first reference low-level signal and a second reference low-level signal. When the current scanning line is inactive, the pull-down maintaining assembly controls the reference low-level to be sent to the current scanning line and the output end of the pull-up control assembly according to a pull-down maintaining signal.

First claim

I claim:

1. A scan driving circuit, comprising:
a pull-up assembly;
a pull-up control assembly that drives the pull-up assembly;
a pull-down maintaining assembly; and
a reference low-level signal comprising a first reference low-level signal and a second reference low-level signal;
wherein an output end of the pull-up assembly is coupled to a current scanning line, an output end of the pull-up control assembly is connected to a control end of the pull-up assembly, electric potential of the second reference low-level signal is less than electric potential of the first reference low-level signal;
when the current scanning line is inactive, the second reference low-level signal is sent to the output end of the pull-up control assembly through the pull-down maintaining assembly, and the first reference low-level signal is also sent to the current scanning line through the pull-down maintaining assembly;
wherein the pull-down maintaining assembly comprises a first pull-down maintaining assembly, the first pull-down maintaining assembly comprises a first pull-down maintaining unit and a first pull-down maintaining control unit that drives the first pull-down maintaining unit; the first pull-down maintaining unit comprises a first controllable switch and a second controllable switch, the pull-down maintaining signal comprises a first pull-down maintaining signal, wherein the first pull-down maintaining signal is sent to control ends of the first controllable switch and the second controllable switch through the first pull-down maintaining control unit; the second reference low-level signal is sent to the output end of the pull-up control assembly through the second controllable switch, and the first reference low-level signal is sent to the current scanning line through the first controllable switch; electric potential of the pull-down maintaining signal, that is at a low level, is less than electric potential of the second reference low-level signal;
when the current scanning line is inactive, the first pull-down maintaining control unit controls the first controllable switch and the second controllable switch to turn on according to the first pull-down maintaining signal, the first controllable switch controls the second reference low-level signal to be sent to the output end of the pull-up control assembly, and the second controllable switch controls the first reference low-level signal to be sent to the current scanning line;
when the current scanning line is active, the first controllable switch and the second controllable switch turn off, the first controllable switch controls the second reference low-level signal not to be sent to the output end of the pull-up control assembly, and the second controllable switch controls the first reference low-level signal not to be sent to the current scanning line.

2. The scan driving circuit of claim 1 , wherein the pull-down maintaining assembly comprises a first pull-down maintaining assembly, a second pull-down maintaining assembly, and a pull-down maintaining signal; input ends of the first pull-down maintaining assembly and the second pull-down maintaining assembly are coupled to the output end of the pull-up control assembly, the pull-down maintaining signal is sent to control ends of the first pull-down maintaining assembly and the second pull-down maintaining assembly, and the reference low-level signal is sent to output ends of the first pull-down maintaining assembly and the second pull-down maintaining assembly;
wherein the scan driving circuit further comprises a diverter switch, the diverter switch is connected between the control end of the first pull-down maintaining assembly and the control end of the second pull-down maintaining assembly a control end of the diverter switch is coupled to the output end of the pull-up control assembly;
when the current scanning line is active, a second controllable switch turns off the first pull-down maintaining assembly and the second pull-down maintaining assembly, causing the reference low-level signal not to be sent to the output end of the pull-up control assembly and the current scanning line.

3. The scan driving circuit of claim 2 , wherein the pull-up control assembly comprises a seventeenth controllable switch; an output end of the seventeenth controllable switch is coupled to the control end of the pull-up assembly, a pull-up control signal is sent to a control end and an input end of the seventeenth controllable switch; the pull-up assembly comprises an eighteenth controllable switch, a control end of the eighteenth controllable switch is coupled to the output end of the seventeenth controllable switch, the clock scanning signal is sent to an input end of the eighteenth controllable switch, and an output end of the eighteenth controllable switch is coupled to the current scanning line; the scan driving circuit further comprises a storage capacitor, a first end of the storage capacitor is coupled to the output end of the pull-up control assembly, and a second end of the storage capacitor is coupled to the output end of the pull-up assembly.

4. The scan driving circuit of claim 1 , wherein the pull-down maintaining signal comprises a second pull-down maintaining signal, logical operation of the first pull-down maintaining signal is opposite to logical operation of the second pull-down maintaining signal; the first pull-down maintaining control unit comprises a third controllable switch, a fourth controllable switch, and a fifth controllable switch; the third controllable switch uses a diode connection method; in the diode connection method, the first pull-down maintaining signal is sent to an input end and a control end of the third controllable switch, an output end of the third controllable switch is coupled to a control end of the fourth controllable switch, and the first pull-down maintaining signal is sent to an input end of the fourth controllable switch; the second pull-down maintaining signal is sent to a control end of the fifth controllable switch, the first pull-down maintaining signal is sent to an input end of the fifth controllable switch, and output ends of the fourth controllable switch and the fifth controllable switch are coupled to the control ends of the first controllable switch and the second controllable switch;
when the current scanning line is inactive, the first controllable switch and the second controllable switch turn on according to the first pull-down maintaining signal and the second pull-down maintaining signal; the first reference low-level signal reduces electric potential of the current scanning line through the first controllable switch, and the second reference low-level signal reduces electric potential of the output end of the pull-up control assembly through the second controllable switch;
when the current scanning line is active, the first controllable switch and the second controllable switch turn off, the second reference low-level signal is not sent to the output end of the pull-up control assembly, and the first reference low-level signal is not sent to the current scanning line.

5. The scan driving circuit of claim 4 , wherein the pull-down maintaining assembly comprises a turn-off unit, the turn-off unit comprises a sixth controllable switch, a control end of the sixth controllable switch is coupled to the output end of the pull-up control assembly, and an input end of the sixth controllable switch is coupled to the control end of the fourth controllable switch; the first reference low-level signal, the second reference low-level signal, or the second pull-down maintaining signal is sent to an output end of the sixth controllable switch.

6. The scan driving circuit of claim 1 , wherein the pull-down maintaining assembly further comprises a second pull-down mai

Assignees

• Shenzhen China Star Optoelect
• Shenzehn China Star Optoelectronics Tech Co Ltd

Inventors

• Dai Chao

Classifications

• G09G2310/06

  Details of flat display driving waveforms · CPC title

• G09G3/3677 Primary

  suitable for active matrices only · CPC title

• G09G2310/08

  Details of timing specific for flat panels, other than clock recovery · CPC title

• G09G2320/0214

  with crosstalk due to leakage current of pixel switch in active matrix panels · CPC title

• G09G3/36

  using liquid crystals · CPC title