Liquid crystal display device

• US 6,816,142 B2
• Filed: 11/13/2001
• Issued: 11/09/2004
• Est. Priority Date: 11/13/2000
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Advanced Display Technologies, Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Yuuki, Akimasa, Tahata, Shin, Miyake, Shiro, Oda, Kyoichiro, Kobayashi, Kazuhiro, Murayama, Keiichi, Tobita, Toshio
• Primary Examiner(s): Tran, Henry N.
• Application Number:
  US09/986,902
• Publication Number:
  US 20020057241A1
• Time in Patent Office: 1,092 Days
• Field of Search: 345/92, 345/102, 345/103, 345/204, 345/87, 345/90, 345/98, 345/100
• US Class Current: 345/89
• 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:

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

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

horizontal driving means for applying a voltage, which corresponds to an image signal, to each pixel in the row selected by turning on the switching means,

signal correcting means for generating a corrected image signal using a transmittance of a previous frame to determine a voltage level necessary for attaining a desired transmittance in a current frame, within one frame period, and for providing the corrected image signal to the horizontal driving means, and

an illumination device having a plurality of light emitting regions for illuminating the display panel, the light emitting regions sequentially turning on and off in synchronization with selection of the rows of each light emitting region, while maintaining a definite time delay in the selection of rows.

2. The liquid crystal display device of claim 1 comprising election means for selectively providing one of the corrected image signal and an erasure signal to the horizontal driving means, wherein the corrected image signals are provided for the pixels in even numbered rows while the erasure signal is provided for the pixels in odd numbered rows during even numbered frames, and the erasure signal is provided for the pixels in the even numbered rows while the corrected image signals are provided for the pixels in the odd numbered rows during odd numbered frames.

3. The liquid crystal display device of claim 1 comprising temperature detecting means for detecting temperature of a liquid crystal material in the display panel, wherein the signal correcting means corrects the level of an image signal using temperature detected as a parameter.

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

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

election means selectively providing one of the corrected image signal and an erasure signal to the horizontal driving means, wherein

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

the corrected image signals are provided for the pixels in even numbered rows while the erasure signal is provided for the pixels in odd numbered rows during even numbered frames, and the erasure signal is provided for the pixels in the even numbered rows while the corrected image signals are provided for the pixels in the odd numbered rows during odd numbered frames.

5. The liquid crystal display device of claim 1, in which currents flowing through respective lamps in the light emitting regions are independently controlled.

6. The liquid crystal display device of claim 1, in which turn on periods of each of the light emitting regions are independently controlled.

7. The liquid crystal display device of claim 1, in which turn on periods of each of the light emitting regions are divided into turn on and turn off sub-periods.

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

9. The liquid crystal display of claim 8 comprising:

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

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

a plurality of signal conversion tables in which output data is stored in correspondence with 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 tables selected based on the temperature detected by the temperature detection circuit.

10. The liquid crystal display of claim 9 wherein the output data in the signal conversion table is determined so 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.

11. The liquid crystal display of claim 8 comprising:

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

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

a plurality of signal conversion tables in which output data is stored in correspondence to a part of each value of the previous frame image signal and a part 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 tables selected based on the temperature detected by the temperature detection circuit.

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

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

14. The liquid crystal display of claim 11 comprising a signal conversion interpolation table in which interpolation differential data is stored in correspondence to part of each value of the previous frame image signal and part of each value of the current frame image signal, wherein the processor determines output data using the signal conversion interpolation table as well as the signal conversion table selected based on the temperature detected.

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

16. A liquid crystal display device comprising:

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

a frame memory for storing a present frame image signal, having bit length converted, for a definite time, to output 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 part 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 using the signal conversion table, and

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

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

temperature detection circuit for detecting temperature of a liquid crystal material of the liquid crystal display, 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 part of each value of the current frame image signal, wherein the processor determines the output data using one of the signal conversion tables selected based on the temperature detected by the temperature detection circuit.

18. A liquid crystal display device of an active matrix type wherein

an interlaced image signal comprising even numbered fields and odd numbered fields is displayed,

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

corrected image signals are provided for pixels in even numbered rows while an erasure signal is provided for pixels in odd numbered rows during even numbered fields, and the erasure signal is provided for the pixels in the even numbered rows while corrected image signals are provided for the pixels in the odd numbered rows during odd numbered fields.

19. The liquid crystal display device of claim 18 comprising an illumination device for illuminating the display area of the liquid crystal display with a plurality of horizontal stripe light emitting regions, wherein

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

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.