Illuminator, image display comprising the same, liquid crystal television, liquid crystal monitor, and liquid crystal information terminal

• US 7,133,019 B2
• Filed: 04/20/2001
• Issued: 11/07/2006
• Est. Priority Date: 04/21/2000
• Status: Expired due to Fees

• Current Assignee: Japan Display Central Incorporated (Japan Display Incorporated)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Ogiwara, Akifumi, Kuratomi, Yasunori, Asayama, Junko, Komori, Kazunori
• Primary Examiner(s): Lefkowitz, Sumati
• Assistant Examiner(s): Xiao, Ke
• Application Number:
  US10/257,774
• Publication Number:
  US 20030184690A1
• Time in Patent Office: 2,027 Days
• Field of Search: 345/102, 349/117, 349/118, 349/94, 349/123, 349/128, 349/132
• US Class Current: 345/102
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• CPC Class Codes: G02B 6/0043 provided on the surface of the light guide
• CPC Class Codes: G02B 6/0051 Diffusing sheet or layer
• CPC Class Codes: G02B 6/0071 with elongated shape, e.g. tube
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side

Abstract

The invention provides an image display apparatus (1) comprising a lighting system (100); a LCD element (304); and an actuating means for varying the transmittance of the LCD element (304) according to image signals, wherein the LCD element (304) is designed such that when the angle of view with respect to a specified direction of a screen varies provided that the entire LCD element (304) is in a white display mode, transmittance varies such that it has peak values at viewing angles other than viewing angles in the vicinity of 0 degree, and wherein the lighting system (100) is designed such that the intensities of light beams emitted in the directions of the viewing angles in the vicinity of 0 degree are higher than the intensities of light beams emitted in the directions of the viewing angles at which the transmittance has a peak value.

Claims

1. An image display apparatus comprising a lighting system including an optical waveguide designed to allow light entering through its end faces to go out through one of its main faces;

and light sources disposed alongside the end faces of the optical waveguide respectively, for emitting light so as to be incident on the end faces;

a LCD element for displaying images by allowing a liquid crystal layer which constitutes a screen to transmit the light emitted from the lighting system with varied transmittance of the liquid crystal layer, the LCD element having a pair of substrates opposed to each other and the liquid crystal layer interposed therebetween; and

actuating means for varying the transmittance of the liquid crystal layer according to image signals,

wherein the LCD element is designed such that when an angle of view with respect to a specified direction of the screen varies, provided that the LCD element is in a white display mode entirely, the transmittance of the liquid crystal layer varies so as to have peak values at viewing angles other than viewing angles in the vicinity of 0 degree,

wherein each light source includes a plurality of elongated arc tubes which have different girths and are placed alongside their associated end face of the optical waveguide; and

a reflecting member for reflecting light coming from the plurality of arc tubes to the associated end face of the optical waveguide,

wherein the thinnest one of the plurality of arc tubes is disposed at a position closer to the associated end face than others, the end faces of the optical waveguide are flat faces perpendicular to the main faces of the optical waveguide, and the plurality of arc tubes are disposed so as not to overlap with one another when viewed from a direction perpendicular to the associated end face, and

wherein the lighting system is designed to emit the light to the LCD element such that intensities of light beams emitted in directions of the viewing angles in the vicinity of 0 degree are higher than intensities of light beams emitted in directions of the viewing angles at which the transmittance of the liquid crystal layer has a peak value.

2. The image display apparatus according to claim 1, wherein when the angle of view varies with respect to said specified direction of the screen, brightness has its peak value at a viewing angle of substantially 0 degree.

3. The image display apparatus according to claim 2, wherein by scattering light beams which have been emitted in a certain direction, the intensities of light beams emitted in the directions of the viewing angles in the vicinity of 0 degree are made to be higher than the intensities of light beams emitted in the directions of the viewing angles at which the transmittance has a peak value.

4. The image display apparatus according to claim 3, wherein the lighting system performs the aforesaid scattering by use of a scattering anisotropic film which scatters light beams coming from angles within a specified range while transmitting light beams coming from other angles than the angles within the specified range.

5. The image display apparatus according to claim 2, wherein the lighting system is designed such that outgoing light beams are collected in the directions of the viewing angles in the vicinity of 0 degree, thereby making the intensities of light beams going out in said directions higher than the intensities of light beams going out in the directions of the viewing angles at which the transmittance has a peak value.

6. The image display apparatus according to claim 5, wherein the lighting system is designed such that said light condensation is carried out by use of a prism sheet for collecting incoming light to send in a certain direction.

7. The image display apparatus according to claim 6, wherein the LCD element is designed such that the transmittance varies so as to have peak values within the viewing angle range of from minus 60 degrees to minus 30 degrees and within the viewing angle range of plus 30 degrees to plus 60 degrees.

8. The image display apparatus according to claim 1, wherein the alignment direction of liquid crystal molecules in the liquid crystal layer of the LCD element is asymmetrical with respect to a vertical direction and lateral direction of the screen.

9. The image display apparatus according to claim 1, wherein an OCB mode LCD element is used as said LCD element.

10. The image display apparatus according to claim 9, wherein said specified direction of the screen is perpendicular to a rubbing direction for aligning the liquid crystal molecules of the liquid crystal layer.

11. The image display apparatus according to claim 1, wherein said specified direction is a lateral direction of the screen.

12. A liquid crystal television comprising the image display apparatus described in claim 1 and a tuner for selecting a channel of TV broadcast signals, wherein the TV picture signals corresponding to the channel which has been selected by the tuner are input to the actuating means of the image display apparatus as the image signals.

13. A liquid crystal monitor comprising the image display apparatus described in claim 1 and a signal processing unit for processing monitor signals, wherein monitor picture signals output from the signal processing unit are input to the actuating means of the image display apparatus as the image signals.

14. A liquid crystal data terminal unit comprising the image display apparatus described in claim 1 and data receiving means for receiving communication data, wherein image signals including required data output from the data receiving means are input to the actuating means of the image display apparatus as the image signals.

15. A lighting system comprising an optical waveguide designed to allow light entering through its end faces to go out through one of its main faces;

and light sources disposed alongside the end faces of the optical waveguide respectively, for emitting light so as to be incident on the end faces,

wherein each light source includes a plurality of elongated arc tubes which have different girths and are placed alongside their associated end face of the optical waveguide; and

a reflecting member for reflecting light coming from the plurality of arc tubes to the associated end face of the optical waveguide, and

wherein the thinnest one of the plurality of arc tubes is disposed at a position closer to the associated end face than others, wherein the end faces of the optical waveguide are flat faces perpendicular to the main faces of the optical waveguide, and wherein the plurality of arc tubes are disposed so as not to overlap with one another when viewed from a direction perpendicular to the associated end face.

16. An image display apparatus comprising:

a lighting system comprising an optical waveguide designed to allow light entering through its end faces to go out through one of its main faces, and light sources disposed alongside the end faces of the optical waveguide respectively, for emitting light so as to be incident on the end faces, wherein each light source includes a plurality of elongated arc tubes which have different girths and are placed alongside their associated end face of the optical waveguide and a reflecting member for reflecting light coming from the plurality of arc tubes to the associated end face of the optical waveguide and wherein the thinnest one of the plurality of arc tubes is disposed at a position closer to the associated end face than others, wherein the end faces of the optical waveguide are flat faces perpendicular to the main faces of the optical waveguide, and wherein the plurality of arc tubes are disposed so as not to overlap with one another when viewed from a direction perpendicular to the associated end face;

an image display element for displaying images by allowing an optical modulator which constitutes a screen to transmit light coming from the lighting system with varied transmittance; and

actuating means for varying the transmittance of the image display element according to image signals.

17. The image display apparatus according to claim 16, wherein the image display element consists of an LCD element which uses a liquid crystal layer as the optical modulator, whereby an LCD is constructed.

18. A liquid crystal television comprising the image display apparatus described in claim 16 and a tuner for selecting a channel of TV broad cast signals, wherein the image display element of the image display apparatus consists of an LCD element which uses a liquid crystal layer as the optical modulator and wherein the TV picture signals corresponding to the channel which has been selected by the tuner are input to the actuating means of the image display apparatus as the image signals.

19. A liquid crystal monitor comprising the image display apparatus described in claim 16 and a signal processing unit for processing monitor signals, wherein the image display element of the image display apparatus consists of an LCD element which uses a liquid crystal layer as the optical modulator and wherein monitor picture signals output from the signal processing unit are input to the actuating means of the image display apparatus as the image signals.

20. A liquid crystal data terminal unit comprising the image display apparatus described in claim 16 and data receiving means for receiving communication data, wherein the image display element of the image display apparatus consists of an LCD element which uses a liquid crystal layer as the optical modulator and wherein image signals including desired data output from the data receiving means are input to the actuating means of the image display apparatus as the image signals.