Liquid crystal display device

• US 20060038771A1
• Filed: 10/07/2005
• Published: 02/23/2006
• Est. Priority Date: 11/30/2000
• Status: Active Grant

• Current Assignee: Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Hitachi, Ltd., Hitachi Device Engineering Co., Ltd. (Japan Display Incorporated)
• Inventors: Ono, Kikuo, Shingai, Akira, Hirakata, Junichi
• Granted Patent: US 7,830,355 B2
• Time in Patent Office: Days
• US Class Current: 345/102
• CPC Class Codes: G09G 2310/0237 Switching ON and OFF the backlight within one frame
• 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 2310/08 Details of timing specific for flat panels, other than clock recovery
• 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 2320/041 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 2320/103 Detection of image changes, e.g. determination of an index representative of the image change
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• 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

Abstract

In a liquid crystal display device having a backlight, the backlight has a first state which outputs a first amount of light and a second state which generates a second amount of light and the time for the first state and the time for the second state are controlled. Due to such a constitution, the liquid crystal display device can display clear motion picture images in spite of a simple constitution thereof. Further, the liquid crystal display device can display clear and bright motion picture images.

Claims

1. A liquid crystal display device having a liquid crystal display panel and a backlight which is arranged on a back surface of the liquid crystal display panel, wherein the backlight includes a plurality of linear light sources which are provided to a surface substantially parallel to a surface of the liquid crystal display panel, are extended in the x direction of the liquid crystal display panel and are arranged in parallel in the y direction, and among respective light sources, at the time of performing the display driving, the light source arranged at a center portion repeats the lighting and the extinguishing and other remaining light sources maintain the lighting.

2. A liquid crystal display device according to claim 1, wherein respective regions which are surrounded by gate signal lines which are extended in the x direction and are arranged in parallel in the y direction and drain signal lines which are extended in the y direction and are arranged in parallel in the x direction on a liquid-crystal-side surface of one of substrates which are arranged to face each other in an opposed manner while sandwiching liquid crystal therebetween are defined as pixel regions and each pixel region is provided with a switching element which is driven by scanning signals from one-side gate signal line and a pixel electrode to which video signals are supplied from the drain signal line through the switching element.

3. A liquid crystal display device according to claim 1, wherein to a portion which faces a plane determined by the respective light sources which repeat the lighting and the extinguishing out of a liquid crystal display portion formed of a mass of respective pixel regions of the liquid crystal display panel, backlight blinking control means which detects the change of the video signals to the pixel electrodes of the respective pixel regions at the portion and increases the duty of the lighting time in response to the degree of magnitude of the change is provided.

12. A liquid crystal display device according to claim 1, wherein the liquid crystal display device includes a mode which enables the display of a motion picture and a still picture by changing over them and the lighting and the extinguishing of the backlight are repeated in the motion picture display mode.

4. A liquid crystal display device having a liquid crystal display panel and a backlight which is arranged on a back surface of the liquid crystal display panel, wherein the backlight includes a plurality of linear light sources which are provided to a surface substantially parallel to a surface of the liquid crystal display panel, are extended in the x direction of the liquid crystal display panel and are arranged in parallel in the y direction, and at the time of performing the display driving, the respective light sources repeat the lighting and the extinguishing and the duty of the lighting of the light source arranged at a center portion is set smaller than the duty of the lighting of the remaining other light sources.

16. A liquid crystal display device according to claim 4, wherein the liquid crystal display device includes a mode which enables the display of a motion picture and a still picture by changing over them and the lighting and the extinguishing of the backlight are repeated in the motion picture display mode.

5. A liquid crystal display device having a liquid crystal display panel in which respective pixel groups to which video signals are supplied are selected in response to scanning signals supplied to gate signal lines and a backlight which is arranged on a back surface of the liquid crystal display panel, wherein the backlight includes a plurality of linear light sources which are provided to a surface substantially parallel to a surface of the liquid crystal display panel, are extended in the direction parallel to the gate signal lines and are arranged in parallel in the direction which intersects the direction parallel to the gate signal lines, and the light source arranged at least at a center portion repeats the lighting and the extinguishing and the light source disposed at least at one of both sides of the center portion maintains the lighting.

17. A liquid crystal display device according to claim 5, wherein the liquid crystal display device includes a mode which enables the display of a motion picture and a still picture by changing over them and the lighting and the extinguishing of the backlight are repeated in the motion picture display mode.

6. A liquid crystal display device having a liquid crystal display panel in which respective pixel groups to which video signals are supplied are selected in response to scanning signals supplied to gate signal lines and a backlight which is arranged on a back surface of the liquid crystal display panel, wherein the backlight includes a plurality of linear light sources which are provided to a surface substantially parallel to a surface of the liquid crystal display panel, are extended in the direction parallel to the gate signal lines and are arranged in parallel in the direction which intersects the direction parallel to the gate signal lines, and at the time of performing the sequential display of respective frames of the liquid crystal display panel, for each frame, the light source arranged at least at a center portion repeats the lighting and the extinguishing without changing a phase and the light source disposed at least at one of both sides of the center portion repeats the lighting and the extinguishing while shifting the phase.

18. A liquid crystal display device according to claim 6, wherein the liquid crystal display device includes a mode which enables the display of a motion picture and a still picture by changing over them and the lighting and the extinguishing of the backlight are repeated in the motion picture display mode.

7. A liquid crystal display device having a liquid crystal display panel in which respective pixel groups to which video signals are supplied are selected in response to scanning signals supplied to gate signal lines and a backlight which is arranged on a back surface of the liquid crystal display panel, wherein the backlight includes a plurality of linear light sources which are provided to a surface substantially parallel to a surface of the liquid crystal display panel, are extended in the direction parallel to the gate signal lines and are arranged in parallel in the direction which intersects the direction parallel to the gate signal lines, and each light source repeats the lighting and the extinguishing at the same frequency and the frequency of the lighting and extinguishing of the light source disposed at least at a center portion is set smaller than the frequency of the lighting and extinguishing of the light sources disposed at least at one of both sides of the center portion.

19. A liquid crystal display device according to claim 7, wherein the liquid crystal display device includes a mode which enables the display of a motion picture and a still picture by changing over them and the lighting and the extinguishing of the backlight are repeated in the motion picture display mode.

8. A liquid crystal display device having a liquid crystal display panel in which respective pixel groups to which video signals are supplied are selected in response to scanning signals supplied to gate signal lines and a backlight which is arranged on a back surface of the liquid crystal display panel, wherein the backlight includes a plurality of linear light sources which are provided to a surface substantially parallel to a surface of the liquid crystal display panel, are extended in the direction parallel to the gate signal lines and are arranged in parallel in the direction which intersects the direction parallel to the gate signal lines, and each light source repeats the lighting and the extinguishing and the duty of the lighting of the light source disposed at least a center portion is set smaller than the duty of the lighting of the light sources disposed at least at one of both sides of the center portion.

20. A liquid crystal display device according to claim 8, wherein the liquid crystal display device includes a mode which enables the display of a motion picture and a still picture by changing over them and the lighting and the extinguishing of the backlight are repeated in the motion picture display mode.

9. A liquid crystal display device having a liquid crystal display panel in which respective pixel groups to which video signals are supplied are selected in response to scanning signals supplied to gate signal lines and a backlight which is arranged on a back surface of the liquid crystal display panel, wherein the backlight includes a plurality of linear light sources which are provided to a surface substantially parallel to a surface of the liquid crystal display panel, are extended in the direction parallel to the gate signal lines and are arranged in parallel in the direction which intersects the direction parallel to the gate signal lines, and the light source disposed at least at a center portion repeats the lighting and the extinguishing and the light source disposed at least at one of both sides of the center portion maintains the lighting and also receives a less amount of a supply current or a supply voltage than the light source disposed at tile center portion.

21. A liquid crystal display device according to claim 9, wherein the liquid crystal display device includes a mode which enables the display of a motion picture and a still picture by changing over them and the lighting and the extinguishing of the backlight are repeated in the motion picture display mode.

10. A liquid crystal display device having a liquid crystal display panel in which respective pixel groups to which video signals are supplied are selected in response to scanning signals supplied to gate signal lines and a backlight which is arranged on a back surface of the liquid crystal display panel, wherein the backlight includes a plurality of linear light sources which are provided to a surface substantially parallel to a surface of the liquid crystal display panel, are extended in the direction parallel to the gate signal lines and are arranged in parallel in the direction which intersects the direction parallel to the gate signal lines, and the light sources disposed at least a center portion repeat the lighting and the extinguishing and the light source disposed at least at one of both sides of the center portion maintains the lighting, and an arrangement pitch between the light sources disposed at least at one of both sides of the center portion is set larger than an arrangement pitch between the neighboring other light sources.

22. A liquid crystal display device according to claim 10, wherein the liquid crystal display device includes a mode which enables the display of a motion picture and a still picture by changing over them and the lighting and the extinguishing of the backlight are repeated in the motion picture display mode.

11. A liquid crystal display device having a liquid crystal display panel in which respective pixel groups to which video signals are supplied are selected in response to scanning signals supplied to gate signal lines and a backlight which is arranged on a back surface of the liquid crystal display panel, wherein the backlight includes a plurality of linear light sources which are provided to a surface substantially parallel to a surface of the liquid crystal display panel, are extended in the direction parallel to the gate signal lines and are arranged in parallel in the direction which intersects the direction parallel to the gate signal lines, and the light source disposed at least a center portion repeats the lighting and the extinguishing and the light source disposed at least at one of both sides of the center portion maintains the lighting, and at least one of the light source disposed at the center portion and one of the light sources disposed at least at one of both sides of the light source disposed at the center portion are capable of controlling the magnitude of a supply current or a supply voltage.

23. A liquid crystal display device according to claim 11, wherein the liquid crystal display device includes a mode which enables the display of a motion picture and a still picture by changing over them and the lighting and the extinguishing of the backlight are repeated in the motion picture display mode.

13. A liquid crystal display device having a liquid crystal display panel which includes a plurality of scanning lines and a backlight which has a plurality of light sources arranged parallel to a virtual surface which is substantially parallel to the liquid crystal display panel, wherein the lighting and the extinguishing of a plurality of these light sources are repeated after the starting of supply of scanning signals and at least one light source is lit with a delay of at least one frame which controls the scanning signals.

14. A liquid crystal display device according to claim 13, wherein the lighting of the light source which is lit with the delay has the time integral value of the frame for controlling the scanning lines which is substantially equal to the time integral value of other frame for controlling the lighting of other light source or the scanning lines.

15. A liquid crystal display device according to claim 13, wherein the delay is set within a range from minus 8 ms to plus 8 ms from the starting point of supply of the scanning signals.