Method and apparatus for measuring response time of liquid crystal, and method and apparatus for driving liquid crystal display device using the same

• US 20040263450A1
• Filed: 06/24/2004
• Published: 12/30/2004
• Est. Priority Date: 06/30/2003
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Philips LCD Company Limited (LG Display Co., Ltd.)
• Inventors: Lee, Oh Hyun, Kil, Jung Ho, Lee, Don Gyou
• Granted Patent: US 7,446,749 B2
• Time in Patent Office: Days
• US Class Current: 345/87
• CPC Class Codes: G09G 2320/0252 Improving the response speed
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 2320/0693 Calibration of display systems
• CPC Class Codes: G09G 2340/16 Determination of a pixel data signal depending on the signal applied in the previous frame
• CPC Class Codes: G09G 3/006 Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309
• CPC Class Codes: G09G 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• CPC Class Codes: G09G 3/2011 by amplitude modulation
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

The method and apparatus for measuring response time of liquid crystal includes controlling temperature of a liquid crystal display panel, generating a liquid crystal driving signal having a variable voltage level that is changed according to a response property of the liquid crystal display panel and a target voltage level, and supplying the liquid crystal driving signal to the liquid crystal display panel, detecting the response property corresponding to the liquid crystal driving signal, and adjusting the variable voltage level until the response property reaches a desired level and setting a modulated data substantially equal to the variable voltage level when the response property reaches the desired level, the modulated data based on temperatures being determined by changing the temperature of the liquid crystal display panel. Also, method and apparatus for driving a LCD device using the above-described method.

Claims

1. A method for measuring response time of liquid crystal, comprising:

generating a liquid crystal driving signal having a variable voltage level that is changed in accordance with a response property of a liquid crystal display panel and a target voltage level;

supplying the liquid crystal driving signal to the liquid crystal display panel;

detecting the response property of the liquid crystal display panel corresponding to the liquid crystal driving signal;

adjusting the variable voltage level until the response property reaches a desired level;

setting a modulated data substantially equal to the variable voltage level when the response property reaches the desired level; and

searching modulated data for different temperatures by changing the temperature of the liquid crystal display panel and by repeating the generating step, the supplying step, the detecting step, the adjusting step and the setting step.

2. The method according to claim 1, wherein the detecting the response property comprises:

detecting a brightness of the liquid crystal display panel;

generating a voltage signal corresponding to the detected brightness;

delaying the voltage signal for one time frame;

detecting a difference between the delayed voltage signal and a non-delayed voltage signal; and

comparing the difference with a predetermined critical value to determine whether the response property reaches the desired level based on the comparison result.

3. A liquid crystal display device including the liquid crystal display panel measured by the method according to claim 1, wherein the liquid crystal display panel comprises first and second substrates bonded to each other with a predetermined space therebetween, and the predetermined space is filled with the liquid crystal.

4. An apparatus for measuring response time of liquid crystal, comprising:

a temperature controller controlling temperature of a liquid crystal display panel;

a signal generator generating a liquid crystal driving signal having a variable voltage level that is changed in accordance with a response property of the liquid crystal display panel and a target voltage level, and supplying the liquid crystal driving signal to the liquid crystal display panel;

a detector detecting the response property of the liquid crystal display panel corresponding to the liquid crystal driving signal; and

a level controller adjusting the variable voltage level until the response property reaches a desired level and setting a modulated data substantially equal to the variable voltage level when the response property reaches the desired level, the modulated data based on temperatures being determined by changing the temperature of the liquid crystal display panel through the temperature controller.

5. The apparatus according to claim 4, further comprising:

a temperature control chamber into which the liquid crystal display panel is loaded;

a temperature sensor detecting the temperature of the liquid crystal display panel; and

a cooling/heating unit changing or maintaining the temperature within the temperature control chamber under control of the temperature controller.

6. The apparatus according to claim 5, further comprising:

a controller controlling the signal generator and the level controller and controlling the temperature controller in response to a temperature signal detected by the temperature sensor.

7. The apparatus according to claim 6,

wherein the detector comprises a photodetector detecting a brightness of the liquid crystal display panel, and generates a voltage signal corresponding to the detected brightness, and

wherein the level controller receives a first voltage signal of a previous time frame and a second voltage signal of a current time frame, detects a difference between the voltage signals, and compares the difference with a predetermined critical value to determine whether or not the response property reaches the desired level based on the comparison result.

8. The apparatus according to claim 6, wherein the liquid crystal driving signal comprises the target voltage level and the variable voltage level, and has a voltage level of at least 3.

9. A method for driving a liquid crystal display device, comprising:

storing modulation data corresponding to a plurality of temperature settings of a liquid crystal display panel;

detecting a current temperature of the liquid crystal display panel;

selecting the modulation data in accordance with the detected current temperature of the liquid crystal display panel; and

modulating source data to be applied to the liquid crystal display panel using the selected modulation data.

10. The method according to claim 9, further comprising determining the modulation data corresponding to the temperature settings,

wherein the step of determining the modulation data corresponding to the temperature settings includes:

driving the liquid crystal display panel with a liquid crystal driving signal having a variable voltage level that is changed in accordance with a response property of the liquid crystal display panel and a target voltage level;

detecting a brightness of the liquid crystal display panel corresponding to the liquid crystal driving signal; and

setting the modulation data substantially equal to the variable voltage level of the liquid crystal driving data when the response property of the liquid crystal display panel reaches a desired level at a particular temperature.

11. The method according to claim 9, wherein the modulation data comprises:

a high temperature modulation data for the liquid crystal display panel in high, temperature;

a normal temperature modulation data for the liquid crystal display panel in normal temperature; and

a low temperature modulation data for the liquid crystal display panel in low temperature.

12. The method according to claim 11, wherein the high temperature is about 40°

C.˜

70°

C., the normal temperature is about 15°

C.˜

35°

C., and the low temperature is about =31 20°

C.˜

10°

C.

13. The method according to claim 11, wherein one of the high temperature modulation data, the normal temperature modulation data and the low temperature modulation data is selected in accordance with the detected current temperature of the liquid crystal display panel for the selecting of the modulation data.

14. A driving apparatus of a liquid crystal display device, comprising:

a temperature sensor detecting a current temperature of a liquid crystal display panel; and

a modulator storing modulation data corresponding to a plurality of temperature settings of the liquid crystal display panel, selecting the modulation data based on the detected current temperature of the liquid crystal display panel, and modulating source data to be applied to the liquid crystal display panel using the selected modulation data.

15. The apparatus according to claim 14, wherein the modulator includes:

a frame memory storing the source data from an input line;

a first look-up table having high temperature modulation data for high temperature;

a second look-up table having normal temperature modulation data for normal temperature;

a third look-up table having low temperature modulation data for low temperature; and

a selector supplying source data from the input line and source data from the frame memory to any one of the first, second and third look-up tables based on the detected current temperature.

16. The apparatus according to claim 15, wherein the high temperature is about 40°

C.˜

70°

C., the normal temperature is about 15°

C.˜

35°

C., and the low temperature is about −

20°

C.˜

10°

C.