Liquid crystal display using swing common electrode voltage and a drive method thereof

• US 7,205,969 B2
• Filed: 09/07/2001
• Issued: 04/17/2007
• Est. Priority Date: 12/18/2000
• Status: Expired due to Fees

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Song, Jang-Kun
• Primary Examiner(s): Nguyen; Jimmy H.
• Application Number:
  US09/947,714
• Publication Number:
  US 20020101415A1
• Time in Patent Office: 2,048 Days
• Field of Search: 345/87, 345/90, 345/92, 345 94- 96, 345/99, 345/100, 345/103
• US Class Current: 345/87
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 2320/0252 Improving the response speed
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/3655 Details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors

Abstract

Disclosed is a liquid crystal display using a swing common electrode voltage and a drive method thereof. The liquid crystal display comprises a timing controller, a data driver, a gate driver outputting gate drive voltages and a drive voltage generator for outputting at least two different common electrode voltages that undergo swinging by synchronizing to a predetermined period with respect to the gate drive voltages. In the method, image signals are received from an external image signal source and supplied to the data lines. Scanning signals are supplied sequentially to the gate lines. Pixel voltage variations are checked. A common electrode voltage ending at positive is output during a gate “on” time to the LCD panel, and A common electrode voltage that repeatedly swings from negative to positive is generated during a gate “off” time if the pixel voltage has varied from negative to positive. A common electrode voltage ending at positive is generated during a gate “on” time to the LCD panel. A common electrode voltage that repeatedly swings from positive to negative is generated during a gate “off” time to the LCD panel if the pixel voltage is varied from positive to negative.

Claims

1. A method for driving a liquid crystal display (LCD), comprising steps of:

turning on a gate electrode for a first predetermined period, wherein a gate voltage does not swing after the first predetermined period for a second predetermined period;

changing a polarity of a pixel voltage from a first polarity to a second polarity during the first predetermined period;

swinging a common electrode voltage after the first predetermined period for the second predetermined period; and

swinging the pixel voltage from said first polarity to said second polarity, and then, from said second polarity to said first polarity during the second predetermined period,

wherein the pixel voltage and the common electrode voltage swing in synchronization during the second predetermined period, and a swinging width of the common electrode voltage is different from that of the pixel voltage.

2. The method of claim 1, wherein a polarity of the common electrode voltage is maintained during the first predetermined period.

3. The method of claim 2, wherein the common electrode voltage maintains said first polarity during the first predetermined period.

4. The method of claim 2, wherein the common electrode voltage maintains said second polarity during the first predetermined period.

5. The method of claim 1, wherein the swinging width of the common electrode voltage is between 12 V to 25 V.

6. The method of claim 1, the LCD is driven by a dot inversion method.

7. A display device, comprising:

a timing controller receiving a synchronization signal and a clock signal and generating a data drive signal, a gate drive signal and a common electrode signal;

a data driver receiving the data drive signal and generating a data voltage;

a gate driver receiving the gate drive signal and generating a gate voltage;

a common signal generator receiving the common electrode signal and generating at least two different common electrode voltages; and

a plurality of pixels formed in a matrix, each pixel comprising;

a pixel electrode;

a switching element supplying the data voltage to the pixel electrode in response to the gate voltage; and

a common electrode receiving one of the common electrode voltages,

wherein the data voltage supplied to the pixel electrode and the common electrode voltage supplied to the common electrode form a liquid crystal capacitance,

wherein, in each pixel, a polarity of a pixel voltage changes from a first polarity to a second polarity while the switching element is turned on for a first predetermined period by the gate voltage, the gate voltage does not swing after the first predetermined period for a second predetermined period, the common electrode voltage swings after the first predetermined period for the second predetermined period, the pixel voltage swings from said first polarity to said second polarity, and then, from said second polarity to said first polarity during the second predetermined period, the pixel voltage and the common electrode voltage swing in synchronization during the second predetermined period, and a swinging width of the common electrode voltage is different from that of the pixel voltage.

8. The display device of claim 7, wherein the common electrode voltage maintains the same polarity for the first predetermined period.

9. The display device of claim 8, wherein the common electrode voltage maintains said first polarity for the first predetermined period.

10. The display device of claim 8, wherein the common electrode voltage maintains said second polarity for the first predetermined period.

11. The display device of claim 8, further comprising:

a plurality of gate lines extending in a first direction and transmitting the gate voltage;

a plurality of data lines extending in a second direction and transmitting the data voltage; and

a plurality of common electrode lines transmitting the common electrode voltages, each common electrode line formed between two neighboring gate lines,

wherein each switching element has a first terminal connected to a corresponding gate line and a second terminal connected to a corresponding data line, and each common electrode is connected to a corresponding common electrode line.

12. The display device of claim 11, wherein the common electrodes of two adjoining pixels are connected to two different common electrode lines, respectively.

13. The display device of claim 12, wherein the display device is driven in a dot inversion method.

14. The display device of claim 11, wherein the common electrode lines are divided into a first group and a second group, wherein the common electrode lines of the first group and the common electrode lines of the second group are alternately arranged.

15. The display device of claim 14, wherein each of the pixels arranged on the odd rows and the odd columns and the even rows and the even columns has the common electrode connected to the common electrode line of the first group, and

each of the pixels arranged on the odd rows and the even columns are the even rows and the even columns has the common electrode connected to the common electrode line of the second group.

16. The display device of claim 7, wherein the swinging width of the common electrode voltage is between 12 V to 25 V.

17. A method of driving a liquid crystal display (LCD), comprising steps of:

providing a gate voltage to a gate electrode to turn on the gate electrode for a first predetermined period, wherein the gate voltage does not swing after the first predetermined period for a second predetermined period;

providing a data voltage to a pixel electrode in response to the gate voltage; and

providing a common voltage to a common electrode, the common voltage swinging after the first predetermined period for the second predetermined period,

wherein a polarity of a pixel voltage changes from a first polarity to a second polarity during the first predetermined period, the pixel voltage swings from said first polarity to said second polarity, and then, from said second polarity to said first polarity during the second predetermined period, the pixel voltage and the common electrode voltage swing in synchronization during the second predetermined period, and a swinging width of the common electrode voltage is different from that of the pixel voltage.

18. The method of claim 17, wherein the swinging width of the common electrode voltage is between 12 V and 25 V.

19. The method of claim 17, the LCD is driven by a dot inversion method.