Light illumination apparatus and liquid crystal display apparatus using the same

• US 20030201969A1
• Filed: 04/21/2003
• Published: 10/30/2003
• Est. Priority Date: 08/03/2000
• Status: Active Grant

• Current Assignee: Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Hitachi, Ltd.
• Inventors: Yamamoto, Tsunenori, Aono, Yoshinori, Hiyama, Ikuo, Tsumura, Makoto
• Granted Patent: US 7,463,235 B2
• Time in Patent Office: Days
• US Class Current: 345/102
• CPC Class Codes: G02B 6/0033 Means for improving the coupling-out of light from the light guide
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0056 for producing polarisation effects, e.g. by a surface with polarizing properties or by an additional polarizing elements
• CPC Class Codes: G02F 1/011 in optical waveguides, not otherwise provided for in this subclass
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/13756 the liquid crystal selectively assuming a light-scattering state G02F1/1334, G02F1/13718 take precedence
• CPC Class Codes: G09G 2300/0434 Flat panel display in which a field is applied parallel to the display plane
• 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 2320/0238 Improving the black level
• 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 2320/0606 Manual adjustment
• CPC Class Codes: G09G 2320/066 for control of contrast
• 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

A light illumination apparatus comprising a light source on a lateral side of a light-pipe, and a reflector on the backside of the light-pipe, further comprising an air layer or the like between the light-pipe and the reflector, and, in order that light coming from a light source into the light-pipe is emitted from a light emission plane, the apparatus further comprising a light scattering control layer disposed at a portion of the light-pipe and having directivity in a direction substantially normal to the light emission plane, a means for substantially removing light scattering characteristics of a predetermined region of the light scattering control layer so as to satisfy the conditions for totally internal reflection of the incident light from the light source at an interface of the light-pipe, and a means for moving the predetermined region, wherein the time average amount of emitted light is substantially equal in each of all light emission regions, and there is time when the light emissive region substantially does not emit light; and a liquid crystal display apparatus using the same.

Claims

1. A light illumination apparatus comprising:

a pair of light-pipes; and

a liquid crystal layer sandwiched between said pair of light-pipes;

said light illumination apparatus further comprising;

a first transparent electrode divided into a plurality of regions disposed on the side of one of said pair of light-pipes faced to said liquid crystal layer;

a second transparent electrode disposed on the side of the other light-pipe faced to said liquid crystal layer;

a light source disposed on a lateral side of at least one of said pair of light-pipes, with an air layer therebetween; and

a first reflector disposed on the side of either one of said pair of light-pipes opposite to the side faced to said liquid crystal layer, with an air layer therebetween;

wherein

said light-pipe attended by said light source has a refractive index of not less than {square root}{fraction ()}2.

2. A light illumination apparatus as set forth in claim 1, further comprising a second reflector or second light source disposed on a lateral side of said light-pipe attended by said light source opposite to the lateral side on which said light source is disposed.

3. A light illumination apparatus as set forth in claim 1 or 2, wherein the surface of one of said pair of light-pipes is rugged.

4. A light illumination apparatus as set forth in claim 1, wherein said first transparent electrode is in the form of stripes.

5. A light illumination apparatus as set forth in claim 1, 2 or 3, wherein said liquid crystal layer is a polymer dispersed liquid crystal (PDLC) layer.

6. A light illumination apparatus as set forth in claim 1, 2 or 3, wherein said liquid crystal layer is a nematic liquid crystal layer.

7. A light illumination apparatus as set forth in claim 4, wherein said first transparent electrode in the form of stripes is composed of n transparent electrode stripes,

said light illumination apparatus further comprises a backlight driving circuit for controlling an electric field impressed between said first transparent electrode and said second transparent electrode,

said backlight driving circuit brings into a scattering condition the regions of said liquid crystal layer corresponding to m transparent electrode stripes (where m is an integer not less than 2, and n≧

m) of said first transparent electrode,

and sequentially moves said scattering condition, and the period of time for which said liquid crystal layer corresponding to each of said n stripes of said first transparent electrode is in the scattering condition is m/n of one frame period.

8. A light illumination apparatus as set forth in claim 7, wherein the value of m is maintained or changed every frame period.

11. A liquid crystal display apparatus comprising:

a liquid crystal display device comprising a plurality of pixels, and a driving circuit portion for controlling the display of said plurality of pixels;

a light illumination apparatus; and

a backlight driving circuit portion for controlling said light illumination apparatus wherein

said liquid crystal display device further comprises a liquid crystal display controller for controlling said driving circuit portion in said liquid crystal display device and said backlight driving circuit portion in said light illumination apparatus, in accordance with inputted picture data;

said light illumination apparatus is a light illumination apparatus as set forth in claim 4;

said first transparent electrode in the form of stripes is composed of n transparent electrode stripes; and

where the period of time for which said liquid crystal display controller performs display on said pixels in said liquid crystal display device is 1/k of one frame period, the number of said first transparent electrode stripes selected as scattering condition at a time is not more than n/k, and k is determined every frame period.

18. A television receiver comprising:

a liquid crystal display device comprising a plurality of pixels, and a driving circuit portion for controlling the display of said plurality of pixels;

a light illumination apparatus; and

a backlight driving circuit portion for controlling said light illumination apparatus, wherein

said liquid crystal display device further comprises a liquid crystal display controller for controlling said driving circuit portion in said liquid crystal display device and said backlight driving circuit portion in said light illumination apparatus, in accordance with inputted picture data;

said light illumination apparatus is a light illumination apparatus as set forth in claim 4;

said first transparent electrode in the form of stripes is composed of n transparent electrode stripes; and

where the period of time for which said liquid crystal display controller performs display on said pixels in said liquid crystal display device is 1/k of one frame period, the number of said first transparent electrode stripes selected as scattering condition at a time is not more than n/k, and k is determined every frame period.

19. A personal digital assistant comprising:

a liquid crystal display device comprising a plurality of pixels, and a driving circuit portion for controlling the display of said plurality of pixels;

a light illumination apparatus; and

a backlight driving circuit portion for controlling said light illumination apparatus, wherein

said liquid crystal display device further comprises a liquid crystal display controller for controlling said driving circuit portion in said liquid crystal display device and said backlight driving circuit portion in said light illumination apparatus, in accordance with inputted picture data;

said light illumination apparatus is a light illumination apparatus as set forth in claim 4;

said first transparent electrode in the form of stripes is composed of n transparent electrode stripes; and

where the period of time for which said liquid crystal display controller performs display on said pixels in said liquid crystal display device is 1/k of one frame period, the number of said first transparent electrode stripes selected as scattering condition at a time is not more than n/k, and k is determined every frame period.

20. A monitor comprising:

a liquid crystal display device comprising a plurality of pixels, and a driving circuit portion for controlling the display of said plurality of pixels;

a light illumination apparatus; and

a backlight driving circuit portion for controlling said light illumination apparatus, wherein

said liquid crystal display device further comprises a liquid crystal display controller for controlling said driving circuit portion in said liquid crystal display device and said backlight driving circuit portion in said light illumination apparatus, in accordance with inputted picture data;

said light illumination apparatus is a light illumination apparatus as set forth in claim 4;

said first transparent electrode in the form of stripes is composed of n transparent electrode stripes; and

where the period of time for which said liquid crystal display controller performs display on said pixels in said liquid crystal display device is 1/k of one frame period, the number of said first transparent electrode stripes selected as scattering condition at a time is not more than n/k, and k is determined every frame period.

21. A display apparatus as set forth in claim 11, wherein picture data inputted to said liquid crystal display apparatus is principally motion picture data.

22. A television receiver as set forth in claim 18, wherein picture data inputted to said television receiver is principally motion picture data.

23. A personal digital assistant as set forth in claim 19, wherein picture data inputted to said personal digital assistant is principally motion picture data.

24. A monitor as set forth in claim 20, wherein picture data inputted to said monitor is principally motion picture data.

9. A liquid crystal display apparatus comprising:

a liquid crystal display device comprising a pair of substrates, a first liquid crystal layer sandwiched between said pair of substrates, and a liquid crystal display device driving circuit for driving said liquid crystal layer; and

a light illumination apparatus comprising a pair of light-pipes, a second liquid crystal layer sandwiched between said pair of light-pipes, and a backlight driving circuit for driving said liquid crystal layer, wherein

driving mode of said first liquid crystal layer is normally open, and

driving mode of said second liquid crystal layer is normally transmissive.

10. A liquid crystal display apparatus comprising:

a liquid crystal display device comprising a pair of substrates, a first liquid crystal layer sandwiched between said pair of substrates, and a liquid crystal display device driving circuit for driving said liquid crystal layer; and

a light illumination apparatus comprising a pair of light-pipes, a second liquid crystal layer sandwiched between said pair of light-pipes, and a backlight driving circuit for driving said liquid crystal layer, wherein

driving mode of said first liquid crystal layer is normally closed, and

driving mode of said second liquid crystal layer is normally scattering.

12. A blanking method comprising the steps of:

selecting predetermined light emission regions from light emission possible regions, and moving said light emission regions in each frame period, wherein

the area of said light emission regions is constant in each frame period, and

the area of said light emission regions is maintained or changed every frame period.

13. A blanking method as set forth in claim 12, wherein

the intensity of light emitted from said light emission regions is controlled when the area of said light emission regions is changed every frame period.

14. A blanking method as set forth in claim 13, wherein

the value obtained upon dividing the intensity of light emitted from said light emission regions by the intensity of light emitted in the case where all of said light emission possible regions are made to be light emission regions is equal to

the value obtained upon dividing the area of said light emission possible regions by the area of said light emission regions.

15. A blanking method as set forth in claim 13, wherein

the value obtained upon dividing the intensity of light emitted from said light emission regions by the intensity of light emitted in the case where all of said light emission possible regions are made to be light emission regions

is not less than one.

16. A blanking method as set forth in claim 12, wherein

said light emission regions are moved so that the period of time for which light is emitted in an arbitrary region of said light emission possible regions is roughly the same in each frame period.

17. A blanking method comprising the steps of:

selecting predetermined light emission regions from light emission possible regions in a light illumination apparatus in accordance with driving scan of a liquid crystal display device, and

moving said light emission regions to input light to said liquid crystal display device, wherein

where said liquid crystal display device displays a picture for 1/k (where k is an integer of not less than

     2) of each frame period,

said light illumination apparatus ensures that the intensity of light emitted from said light emission regions is not less than k times the intensity of light emitted in the case where all of said light emission possible regions are made to be light emission regions.

25. A light illumination apparatus comprising:

a pair of light-pipes; and

a liquid crystal layer sandwiched between said pair of light-pipes;

said light illumination apparatus further comprising;

a first transparent electrode divided into a plurality of regions disposed on the side of one of said pair of light-pipes faced to said liquid crystal layer;

a second transparent electrode disposed on the side of the other light-pipe faced to said liquid crystal layer;

a light source disposed on a lateral side of at least one of said pair of light-pipes; and

a first reflector disposed on the side of either one of said pair of light-pipes opposite to the side faced to said liquid crystal layer;

wherein

the surface of one of said pair of light-pipes is rugged.

26. A light illumination apparatus comprising:

a pair of light-pipes; and

a liquid crystal layer sandwiched between said pair of light-pipes;

said light illumination apparatus further comprising;

a first transparent electrode divided into a plurality of regions disposed on the side of one of said pair of light-pipes faced to said liquid crystal layer;

a second transparent electrode disposed on the side of the other light-pipe faced to said liquid crystal layer;

a light source disposed on a lateral side of at least one of said pair of light-pipes; and

a first reflector disposed on the side of either one of said pair of light-pipes opposite to the side faced to said liquid crystal layer, with a space therebetween.

27. A light illumination apparatus comprising:

a pair of light-pipes; and

a liquid crystal layer sandwiched between said pair of light-pipes;

said light illumination apparatus further comprising;

a first transparent electrode divided into a plurality of regions disposed on the side of one of said pair of light-pipes faced to said liquid crystal layer;

a second transparent electrode disposed on the side of the other light-pipe faced to said liquid crystal layer;

a light source disposed on a lateral side of at least one of said pair of light-pipes; and

a first reflector disposed on the side of either one of said pair of light-pipes opposite to the side faced to said liquid crystal layer, with a medium therebetween, said medium having a refractive index lower than the refractive index of said light-pipe attended by said light source.