Liquid crystal display device and driving control method thereof

• US 20020057243A1
• Filed: 11/07/2001
• Published: 05/16/2002
• Est. Priority Date: 11/10/2000
• Status: Active Grant

• Current Assignee: Casio Computer Company Limited
• Original Assignee: Casio Computer Company Limited
• Inventors: Shimomaki, Shinichi
• Granted Patent: US 7,221,344 B2
• Time in Patent Office: Days
• US Class Current: 345/87
• CPC Class Codes: G09G 2320/0219 Reducing feedthrough effects in active matrix panels, i.e. voltage changes on the scan electrode influencing the pixel voltage due to capacitive coupling
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3655 Details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors

Abstract

In a liquid crystal display device of an active matrix type, at first, an initialization signal voltage having a voltage value equal to or higher than the maximum voltage value of a display signal is applied to display pixels in a signal application period in a field period. The display signal is thereafter applied. As a result, the change amount of the voltage applied to liquid crystal due to the field-through voltage in relation to a gate pulse can be arranged to be substantially constant, and can always be cancelled by a common electrode voltage. Occurrence of flicker and seizure phenomena can be thereby restricted so that the display quality can be improved.

Claims

1. A liquid crystal display device comprising:

a liquid crystal display panel having a plurality of signal lines, a plurality of scanning lines, and a plurality of display pixels arrayed in a matrix and provided respectively near cross-points between the signal lines and the scanning lines through switching elements; and

a driver which supplies the plurality of signal lines with a display signal in a field period, and which scans the plurality of scanning lines, to apply the display signal to the plurality of display pixels, wherein

the driver applies a predetermined initialization signal voltage to the display pixels, and thereafter applies the display signal in at least one signal application period set within the field period.

2. The device according to claim 1, wherein

the liquid crystal display panel includes a plurality of pixel electrodes arrayed in a matrix through the switching elements, and common electrodes opposed to the pixel electrodes, and

the display pixels comprise the pixel electrodes, the common electrodes, and liquid crystal sandwiched between the pixel electrodes and the common electrodes.

3. The device according to claim 1, wherein each of the switching elements of the liquid crystal display panel includes a thin film transistor.

4. The apparatus according to claim 1, wherein

the driver applies the initialization signal voltage to the display pixels and thereafter applies the display signal after a predetermined hold time, in the signal application period in the field period, and

the hold time is set to a time equal to or longer than a voltage-write response time of the display pixels.

5. The device according to claim 1, wherein

the initialization signal voltage in the driver has a value equal to or higher than a maximum voltage value of the display signal.

6. The device according to claim 1, wherein

the driver applies the initialization signal voltage and the display signal to the display pixels connected to the scanning lines of the liquid crystal display panel, at a predetermined time interval, sequentially for every one of the scanning lines, in the signal application period in the field period, and

the time interval is set to a value at which timings of applying the initialization signal voltage and the display signal to every of the display pixels connected to each of the scanning lines do not overlap each other.

7. The device according to claim 1, wherein

application timing is set such that the driver applies the initialization signal voltage simultaneously to all the display pixels of the liquid crystal display panel, and thereafter applies the display signal to the display pixels connected to the scanning lines of the liquid crystal display panel, at a predetermined time interval, sequentially for every one of the scanning lines, in the signal application period in the field period.

8. The device according to claim 1, wherein

the driver provides three signal application periods in one field period.

9. The device according to claim 8, wherein

the display signal comprises first, second, and third color component signals, and

the driver applies the initialization signal voltage and thereafter applies any one of the first, second, and third color component signals, to the display pixels connected to the scanning lines of the liquid crystal display panel, sequentially for every one of the scanning lines, in each of the signal application periods of the field period.

10. The device according to claim 9, further comprising an illumination light source capable of controlling light emission color,

the illumination light source being controlled to have light emission color corresponding to any one of the first, second, and third color component signals that is applied by the driver in each of the signal application period.

11. The device according to claim 8, wherein of the display signal, the first color component signal is a red component signal, the second color component signal is a green component signal, and the first color component signal is a blue component signal.

13. The method according to claim 12, further comprising providing of a predetermined voltage hold time after completion of the applying of the initialization signal voltage to the display pixels, wherein

the applying of the display signal includes applying the display signal to the display pixels after the voltage hold time has passed after the applying of the initialization signal voltage, and

the hold time is set to a time equal to or longer than a voltage-write response time of the display pixels.

14. The method according to claim 12, wherein

the initialization signal voltage has a value equal to or higher than a maximum voltage value of the display signal.

15. The method according to claim 12, wherein the applying of the initialization signal voltage includes applying the initialization signal voltage to the display pixels connected to the scanning lines, sequentially for every one of the scanning lines,

the applying of the display signal includes applying the display signal to the display pixels connected to the scanning lines, sequentially for every one of the scanning lines, and

application timings of applying the initialization signal voltage and the display signal for every one of the scanning line are set so as not to overlap each other.

16. The method according to claim 12, wherein

the applying of the initialization signal voltage includes applying the initialization signal voltage simultaneously to all the display pixels connected to the scanning lines.

17. The method according to claim 12, wherein

the providing of the signal application period in the field period includes providing three signal application periods in one field period.

18. The method according to claim 17, wherein

the display signal comprises first, second, and third color component signals, and the applying of the initialization signal voltage includes applying the initialization signal voltage simultaneously to the plurality of display pixels connected to the scanning lines, in each of the signal application periods, and

the applying of the display signal includes applying any of the first, second, and third color component signals, to the display pixels connected to the scanning lines, sequentially for every one of the scanning lines, in each of the signal application periods.

19. The method according to claim 18, further comprising controlling light emission color of an illumination light source, wherein

the controlling of the light emission color includes controlling the light emission color of the light source so as to correspond to any of the first, second, and third color component signals that is applied to the display pixels in the applying of the display signal.

12. A drive control method for a liquid crystal display device which has a plurality of signal lines, a plurality of scanning lines, and a plurality of display pixels arrayed in a matrix and provided respectively near cross-points between the signal lines and the scanning lines through switching elements, and which supplies the plurality of signal lines with a display signal in a field period and scans the plurality of scanning lines, to apply the display signal to the plurality of display pixels, comprising:

providing at least one signal application period in the field period;

applying a predetermined initialization signal voltage to the display pixels in the signal application period; and

applying the display signal to the display pixels after completion of the applying of the initialization signal voltage in the signal application period.