Scan driver, display device having the same and method of driving a display device

• US 8,872,752 B2
• Filed: 10/10/2012
• Issued: 10/28/2014
• Est. Priority Date: 07/28/2005
• Status: Active Grant

• Current Assignee: TCL China Star Optoelectronics Technology Co. Ltd. (TCL Technology Group Corp.)
• Original Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: Kim, Sung-Man, Lee, Bong-Jun, Kang, Shin-Tack, Park, Hyeong-Jun, Lee, Yong-Woo
• Primary Examiner(s): Sitta, Grant
• Application Number:
  US13/648,505
• Publication Number:
  US 20130033417A1
• Time in Patent Office: 748 Days
• Field of Search: 345/100
• US Class Current: 345/100
• CPC Class Codes: G09G 2310/0248 Precharge or discharge of column electrodes before or after applying exact column voltages
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/3677 suitable for active matrices only
• CPC Class Codes: G11C 19/184 with field-effect transistors, e.g. MOS-FET

Abstract

A scan driver drives a display device having a plurality of gate lines transferring scan signals, and a plurality of source lines transferring data signals. The scan driver includes a shift register and a multiple signal applying unit. The shift register includes a plurality of cascade-connected stages, each stage having an output terminal electrically connected to a respective one of the plurality of gate lines. The multiple signal applying unit applies a sub scan signal and a main scan signal. The sub scan signal and the main scan signal sequentially activate each of the plurality of gate lines. Therefore, the scan lines receive the scan signal twice, so that the liquid crystal capacitors electrically connected to the gate lines receive the data voltage twice. As a result, even though the time for charging the liquid crystal capacitors may be reduced, the liquid crystal capacitors may be fully charged to enhance display quality.

Claims

1. A scan driver driving a display device having a plurality of gate lines transferring scan signals, and a plurality of source lines transferring data signals, the scan driver comprising:

a shift register including a plurality of cascade-connected stages having a first stage connected to a first gate line, each stage having an output terminal electrically connected to a respective one of the plurality of gate lines; and

a multiple signal applying unit applying a sub scan signal and a main scan signal, the sub scan signal and the main scan signal sequentially activating each of the plurality of gate lines, wherein the multiple signal applying unit comprises a starting part and an ending part, each of the starting part and the ending part includes ‘

I’

number of stages, a last stage of the starting part is cascade-connected to the first stage of the shift register, and a last stage of the shift register is cascade-connected to a first stage of the ending part,

wherein the ‘

I’

number of stages of the starting part and the ‘

I’

number of stages of the ending part are separated from the gate lines so that none of the ‘

I’

number of stages of the starting part and the ‘

I’

number of stages of the ending part is connected to the gate lines, and

wherein an output of a stage of the ‘

I’

number of stages of the ending part is inputted to a successive stage of the ‘

I’

number of stages of the ending part.

2. The scan driver of claim 1, wherein a scan start signal for driving the shift register is simultaneously applied to both of a first stage of the starting part and the first stage of the shift register.

3. The scan driver of claim 2, further comprising a diode formed on a line through which the scan start signal is applied to the first stage of the shift register, the diode preventing a carry signal outputted from the last stage of the starting part from being applied to the first stage of the starting part.

4. The scan driver of claim 3, wherein the diode is an amorphous silicon thin-film transistor having a gate electrode and a drain electrode electrically connected to each other.

5. The scan driver of claim 1, wherein a starting part of the multiple signal applying unit is adjacent to a first stage of the shift register, and an ending part of the multiple signal applying unit is adjacent to a last stage of the shift register.

6. A display device comprising:

a liquid crystal display panel including a plurality of gate lines transferring scan signals, and a plurality of source lines transferring data signals; and

a scan driver driving the liquid crystal display panel, the scan driver including;

a shift register including a plurality of cascade-connected stages having a first stage connected to a first gate line, each stage having an output terminal electrically connected to a respective of the plurality of gate lines; and

a multiple signal applying unit applying a sub scan signal and a main scan signal, the sub scan signal and the main scan signal sequentially activating each of the plurality of gate lines, wherein the multiple signal applying unit comprises a starting part and an ending part, each of the starting part and the ending part includes ‘

I’

number of stages, a last stage of the starting part is cascade-connected to the first stage of the shift register, and a last stage of the shift register is cascade-connected to a first stage of the ending part,

wherein the ‘

I’

number of stages of the starting part and the ‘

I’

number of stages of the ending part are separated from the gate lines so that none of the ‘

I’

number of stages of the starting part and the ‘

I’

number of stages of the ending part is connected to the gate lines, and

wherein an output of a stage of the ‘

I’

number of stages of the ending part is inputted to a successive stage of the ‘

I’

number of stages of the ending part.

7. The display device of claim 6, wherein a scan start signal for driving the shift register is simultaneously applied to both of a first stage of the starting part and the first stage of the shift register.

8. The display device of claim 7, further comprising a diode formed on a line through which the scan start signal is applied to the first stage of the shift register, the diode preventing a carry signal outputted from the last stage of the starting part from being applied to the first stage of the starting part.

9. The display device of claim 6, wherein a starting part of the multiple signal applying unit is adjacent to a first stage of the shift register, and an ending part of the multiple signal applying unit is adjacent to a last stage of the shift register.