Liquid crystal display device

• US 20020057241A1
• Filed: 11/13/2001
• Published: 05/16/2002
• Est. Priority Date: 11/13/2000
• Status: Active Grant

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Yuuki, Akimasa, Tahata, Shin, Miyake, Shiro, Oda, Kyoichiro, Kobayashi, Kazuhiro, Murayama, Keiichi, Tobita, Toshio
• Granted Patent: US 6,816,142 B2
• Time in Patent Office: Days
• US Class Current: 345/87
• CPC Class Codes: G09G 2310/0224 Details of interlacing
• CPC Class Codes: G09G 2310/024 Scrolling of light from the illumination source over the display in combination with the scanning of the display screen
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/0252 Improving the response speed
• CPC Class Codes: G09G 2320/0261 in the context of movement of objects on the screen or movement of the observer relative to the screen
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• 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 3/2011 by amplitude modulation
• CPC Class Codes: G09G 3/342 using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

A liquid crystal display device comprising a signal correcting means for correcting a level of an original image signal to a level with which transmittance in a steady state of the pixel with the original image signal is attained within one frame period, a horizontal driving means for applying a voltage in correspondence with the corrected image signal to liquid crystal, and an illumination device for illuminating the display panel with a plurality of light emitting regions thereof, said light emitting regions sequentially turns on and off in synchronization with the application of the corrected image signal while holding a definite time delay thereto.

Claims

1. A liquid crystal display device comprising:

a display panel having pixels arranged in a matrix-like rows and columns configuration and switching means connected to each of the pixels,

a vertical driving circuit for scanning the whole display area of the display panel over one frame period by selecting the rows of pixels alternately while turning on the switching means connected thereto, and

a horizontal driving means for applying voltage, which corresponds to an image signal, to each pixel in said selected row through the switching means being turned on,

wherein a signal correcting means, for correcting a level of an original image signal to a level with which transmittance in a steady state of the pixel with the original image signal is attained within one frame period and providing the corrected image signal to the horizontal driving means, is provided, and

wherein an illumination device for illuminating the display panel with a plurality of light emitting regions thereof, said light emitting regions sequentially turns on and off in synchronization with the selection of rows belonging to each region while holding a definite time delay to the selection of rows, is provided.

2. The liquid crystal display device of claim 1 comprising:

an election means for selectively providing the corrected image signal or an erasure signal to the horizontal driving means,

wherein the corrected image signals are provided for the pixels in even number rows while the erasure signal is provided for the pixels in odd number rows at even number frames and the erasure signal is provided for the pixels in even number rows while the corrected image signals are provided for the pixels in odd number rows at odd number frames.

3. The liquid crystal display device of claim 1 comprising:

a temperature detecting means for detecting temperature of liquid crystal in the display panel,

wherein the signal correcting means corrects the level of the image signal using detected temperature as a parameter.

4. The liquid crystal display device of claim 1 comprising:

a temperature detecting means for detecting temperature of liquid crystal in the display panel, and

an election means selectively provides the corrected image signal or an erasure signal to the horizontal driving means,

wherein the signal correcting means corrects the level of the image signal using detected temperature as a parameter, and

wherein the corrected image signals are provided for the pixels in even number rows while the erasure signal is provided for the pixels in odd number rows at even number frames and the erasure signal is provided for the pixels in even number rows while the corrected image signals are provided for the pixels in odd number rows at odd number frames.

5. The liquid crystal display device of claim 1, in which current flowing through a lamp in each light emitting region is independently controlled with each other.

6. The liquid crystal display device of claim 1, in which turn on period of each light emitting region is independently controlled with each other.

7. The liquid crystal display device of claim 1, in which turn on period of each light emitting region is further divided into sub-periods of turn on and turn off.

8. A liquid crystal display device in which an image signal of current frame is externally input, a voltage with which transmittance designated by said current frame image data is attained within one frame period is applied to liquid crystal at the current frame, and said voltage applied to the liquid crystal varies in accordance with temperature of liquid crystal.

9. The liquid crystal display of claim 8 wherein the voltage applied to the liquid crystal at the current frame is determined depending on the current frame image data and a previous frame image data.

10. The liquid crystal display of claim 9 comprising:

a temperature detection circuit for detecting the temperature of liquid crystal,

a frame memory for storing a present frame image signal for a definite time to output as a previous frame image signal,

a plurality of signal conversion tables in which output data is stored in correspondence to the each value of the previous frame image signal and each value of the current frame image signal, and

a processor for determining the output data from the current frame image signal and the previous frame image signal by using one of the signal conversion table selected on the basis of the detected temperature of the temperature detection circuit are provided.

11. The liquid crystal display of claim 9 comprising:

a temperature detection circuit for detecting the temperature of liquid crystal,

a frame memory for storing a present frame image signal for a definite time to output as a previous frame image signal,

a plurality of signal conversion tables in which output data is stored in correspondence to some of each value of the previous frame image signal and some of each value of the current frame image signal, and

a processor for determining the output data from the current frame image signal and the previous frame image signal by using one of the signal conversion table selected on the basis of the detected temperature of the temperature detection circuit are provided.

12. The liquid crystal display of claim 11 wherein the frame memory stores a present frame image signal having bit length thereof converted for a definite time and outputs as a previous frame image signal.

13. The liquid crystal display of claim 11 comprising:

a signal conversion interpolation table in which interpolation differential data is stored in correspondence to some of each value of the previous frame image signal and some of each value of the current frame image signal,

wherein the processor determines the output data by using the signal conversion interpolation table as well as the signal conversion table selected on the basis of the detected temperature.

14. The liquid crystal display of claim 13 wherein the frame memory stores a present frame image signal having bit length thereof converted for a definite time and outputs as a previous frame image signal.

16. The liquid crystal display of claim 15 further comprising:

a temperature detection circuit for detecting a temperature of liquid crystal, and

a plurality of signal conversion tables in which output data is stored in correspondence to each value of the previous frame image signal and some of each value of the current frame image signal,

wherein the processor for determining the output data by using one of the signal conversion tables selected on the basis of the detected temperature of the temperature detection circuit.

17. The liquid crystal display of claim 12 wherein the number of gradations represented by the previous frame image signal having bit length thereof converted is equal to the number of gradations of the previous frame image signal in the signal conversion table.

18. The liquid crystal display of claim 10 wherein the output data in the signal conversion table is determined in a manner that a transmittance designated by the current frame image signal is attained within one frame period by applying a voltage determined by the output data.

20. The liquid crystal display device of claim 19 comprising an illumination device for illuminating the display area of the liquid crystal display with a plurality of horizontal stripe light emitting regions thereof,

wherein each light emitting region turns on only for a predetermined period which is delayed from the completion of the selection of rows in each light emitting region, and

wherein the level of original image signal is corrected to a level with which transmittance in a steady state of the pixel with the original image signal is attained within one field.

15. A liquid crystal display device comprising:

a converting means for converting a bit length of the current frame image signal,

a frame memory for storing a present frame image signal, having bit length thereof converted, for a definite time to output as a previous frame image signal,

a signal conversion table in which output data is stored in correspondence to each value of the previous frame image signal and some of each value of the current frame image signal, a processor for determining the output data from the current frame image signal and the previous frame image signal by using the signal conversion table, and

an illumination device for illuminating the display area of the liquid crystal display with a plurality of horizontal stripe light emitting regions thereof.

19. A liquid crystal display device of an active matrix type in which an image signal of interlaced type comprising even number fields and odd number fields is displayed,

wherein an original image signal designating a image to be displayed is corrected so as to enlarge a level difference between the original image signal and an erasure signal, and

wherein corrected image signals are provided for the pixels in even number rows while a erasure signal is provided for the pixels in odd number rows at even number fields and the erasure signal is provided for the pixels in even number rows while corrected image signals are provided for the pixels in odd number rows at odd number fields.