OPTICAL ELEMENT, DISPLAY DEVICE, AND TERMINAL DEVICE

Abstract

A plurality of pixels is arranged periodically in the x-axis direction and the y-axis direction in the display panel of a display device, and because light is blocked by the portion other than the open part in each pixel, the display panel has a two-dimensional lattice structure. The pixels are rectangular, and the length Px of the long edges in the x direction is larger than the length Py of the short edges in the y direction. A louver, in which transparent regions and non-transparent regions are arranged periodically in a one-dimensional direction, is provided on the display panel, and the angle formed by the x axis and the one-dimensional period direction of the louver is 45 degrees or less, and preferably 10 degrees or less. This configuration makes it possible to obtain an optical element having high directivity, reduced moiré, and high transmittance. It is also possible to obtain a display device having excellent display quality into which the optical element is incorporated.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view showing the conventional privacy enabling device disclosed in Japanese Patent Application Laid-Open No. 2003-131202;

FIG. 2 is a top view showing the placement of the directional optical filter in relation to the display surface of the display device disclosed in Japanese Patent Application Laid-Open No. 60-15970;

FIG. 3 is a schematic perspective view showing the conventional display device provided with a directional optical filter for prevention of surreptitious viewing disclosed in Japanese Patent Application Laid-Open No. 60-159702;

FIG. 4 is a schematic structural diagram showing a conventional raster display device provided with a light control film disclosed in Japanese Patent No. 2622762;

FIG. 5 is a top view showing the positioning of the light control film with respect to the display surface of the display device;

FIG. 6 is a graph showing the relationship between the pitch p of the moiré stripes, and the angle β between the raster of the display device and the stripes of the light control film;

FIG. 7 is a schematic sectional view showing the conventional viewing-angle-controlled liquid crystal display device described in Japanese Patent Application Laid-Open No. 9-244018;

FIG. 8 is a schematic perspective view showing the illumination device used in the conventional viewing-angle-controlled liquid crystal display device described in Japanese Patent Application Laid-Open No. 9-244018;

FIG. 9 is a schematic perspective view showing the conventional viewing-angle-controlled liquid crystal display device described in Japanese Patent Application Laid-Open No. 9-244018;

FIG. 10 is a schematic top view showing the conventionally utilized pixel structure having four colors of sub-pixels;

FIG. 11A is a schematic plan view showing the light-direction regulating element; FIG. 11B is a schematic plan view showing the two-dimensional lattice sheet, wherein the two-dimensional lattice is shown in real space in the xy plane; FIG. 11C is a schematic plan view showing the two-dimensional lattice sheet, wherein the two-dimensional lattice is shown in real space in the xy plane; FIG. 11D is a diagram showing the inverse lattice in wavenumber space that corresponds to the one-dimensional lattice shown in FIG. 11A; FIG. 11E is a diagram showing the inverse lattice in wavenumber space that corresponds to the two-dimensional lattice shown in FIG. 11B; and FIG. 11F is a diagram showing the inverse lattice in wavenumber space that corresponds to the two-dimensional lattice shown in FIG. 11C;

FIG. 12A is a plan view that corresponds to a case in which the light-direction regulating element in FIG. 11A is superposed on the two-dimensional lattice sheet in FIG. 11B; and FIG. 12B is a diagram showing the arrangement in FIG. 12A in wavenumber space;

FIG. 13A is a plan view that corresponds to a case in which the light-direction regulating element in FIG. 11A is superposed on the two-dimensional lattice sheet in FIG. 11C; and FIG. 13B is a diagram showing the arrangement in FIG. 13A in wavenumber space;

FIG. 14A is a diagram of a case in which the angle formed by the wavenumber vectors f_x and f_y in FIG. 13B is less than 90 degrees; and FIG. 14B is a diagram of a case in which the angle formed by the wavenumber vectors f_x and f_y in FIG. 12B is less than 90 degrees;

FIG. 15 is a perspective view showing the relationship between the two-dimensional lattice vectors and the vantage point when the optical element is observed from a tilted direction;

FIG. 16 is a schematic view in which θ=0 degrees, and the x axis is observed from a vantage point at point-ahead angle φ;

FIG. 17 is a diagram showing the dependence of the wavenumber vector on the point-ahead angle φ in FIG. 13B;

FIG. 18 is a diagram showing the dependence of the wavenumber vector on the point-ahead angle φ in FIG. 12B;

FIG. 19 is a schematic plan view showing the pixel structure of the liquid crystal display element in a seventh embodiment of the present invention;

FIG. 20 is a schematic plan view showing the comb-shaped electrodes provided to the open parts of a pixel;

FIG. 21 is a perspective view showing the display device according to a third embodiment of the present invention;

FIG. 22 is a top view showing the louver used in the third embodiment;

FIG. 23 is a top view showing the positional relationship between the louver and a pixel in the third embodiment;

FIG. 24 is a perspective view showing the display device according to a fourth embodiment of the present invention;

FIG. 25 is a top view showing the pixel arrangement of the display panel, and the louver that is the light-direction regulating element used in the display device according to a fifth embodiment of the present invention;

FIG. 26 is a top view showing the pixel structure in the in-plane switching liquid crystal display device according to a sixth embodiment of the present invention;

FIG. 27 is a top view showing the pixel arrangement in the display device according to an eighth embodiment of the present invention;

FIG. 28 is a sectional view showing the transparent/scattering switching element used in a ninth embodiment of the present invention;

FIG. 29 is a perspective view showing the display device according to the ninth embodiment of the present invention;

FIG. 30 is a perspective view showing a mobile telephone in which the display device of the present invention is mounted;

FIG. 31 is a top view showing a pixel arranged in the display panel of a tenth embodiment of the present invention;

FIG. 32 is a top view showing a pixel of the display device according to a first modified example of the tenth embodiment of the present invention;

FIG. 33 is a perspective view showing the three-dimensional image display device according to a second modified example of the tenth embodiment of the present invention; and

FIG. 34 is an optical model diagram showing a cross section of the three-dimensional image display device along line A-A in FIG. 33.

Claims

1. An optical element comprising: a two-dimensional lattice sheet composed of transparent regions and non-transparent regions that are periodically arranged in alternating fashion in a first direction and a second direction that intersects the first direction; anda light-direction regulating element that is superposed on said two-dimensional lattice sheet and is composed of transparent regions and non-transparent regions periodically arranged in alternating fashion in a third direction parallel to a surface of said two-dimensional lattice sheet; whereina minimum cycle in said first direction of said two-dimensional lattice sheet is larger than a minimum cycle in said second direction; anda first primitive translation vector in said first direction whose size is the minimum cycle in said first direction of said two-dimensional lattice sheet, a second primitive translation vector in said second direction whose size is the minimum cycle of said second direction of said two-dimensional lattice sheet, and a third primitive translation vector in said third direction whose size is the minimum cycle in said third direction of said light-direction regulating element are related so that an angle between said third primitive translation vector and said first primitive translation vector is equal to one-half or less of an angle between said first primitive translation vector and said second primitive translation vector.

2. The optical element according to claim 1, wherein said light-direction regulating element has periodic properties whereby transparent regions and non-transparent regions are arranged in alternating fashion in a fourth direction that intersects said third direction and is parallel to a surface of said two-dimensional lattice sheet;a minimum cycle in said fourth direction of said light-direction regulating element is larger than a minimum cycle in said third direction; andan angle between said second primitive translation vector and a fourth primitive translation vector in said fourth direction whose size is the minimum cycle in said fourth direction of said light-direction regulating element is one-half or less of an angle between said first primitive translation vector and said second primitive translation vector.

3. A display device comprising the optical element according to claim 1, wherein said two-dimensional lattice sheet is a display panel; andsaid light-direction regulating element is a louver.

4. The display device according to claim 3, wherein said display panel is a reflective liquid crystal panel or a self-luminous display panel.

5. The display device according to claim 3, wherein said display device has a backlight; andsaid display panel is a transmissive liquid crystal panel or a transflective liquid crystal panel.

6. The display device according to claim 4, wherein said louver and said display panel are arranged in the following sequence from the direction of an observer: louver, display panel.

7. The display device according to claim 5, wherein said louver and said display panel are arranged in the following sequence from the direction of an observer: louver, display panel.

8. The display device according to claim 5, wherein said display panel, said louver, and said backlight are arranged in the following sequence from the direction of an observer: display panel, louver, backlight.

9. The display device according to claim 3, wherein said display panel has a display region in which pixels are arranged in a matrix;said transparent regions of said two-dimensional lattice sheet are open parts of the pixels; andsaid non-transparent regions constitute a black matrix having light-blocking properties that is formed in said pixels.

10. The display device according to claim 9, wherein said display panel is composed of sub-pixels having color filters in a display surface;a striped color pattern is formed by said color filters;said display panel divided into a lattice by said sub-pixels has two-dimensional translational symmetry in which long edges and short edges of said sub-pixels constitute a period; andan angle of 80 to 100 degrees is formed by a periodic arrangement direction of said striped pattern and a larger primitive translation vector of two primitive translation vectors having two-dimensional translational symmetry.

11. The display device according to claim 10, wherein a periodic arrangement direction of said striped pattern is orthogonal to said larger primitive translation vector.

12. The display device according to claim 10, wherein said display panel pixels are composed of four or more colors of sub-pixels.

13. The display device according to claim 10, wherein said display panel has color filters composed of three or more colors in a display surface;two or more sub-pixels are provided with respect to a single type of color disposed within a single pixel; andeach sub-pixel is individually controlled by an independent display signal.

14. The display device according to claim 3, wherein said display panel is a liquid crystal panel;periodically arranged structures are provided for dividing and orienting liquid crystals in open parts of pixels; andan angle of 80 to 100 degrees is formed by the periodic arrangement direction and said third direction.

15. The display device according to claim 3, wherein said display panel is an in-plane switching liquid crystal panel;electrodes are provided in periodic fashion for generating an in-plane field or an out-of-plane field in open parts of pixels; andan angle of 80 to 100 degrees is formed by the periodic arrangement direction and said third direction.

16. The display device according to claim 3, comprising a transparent/scattering switching element capable of switching between a state of transmitting incident light and a state of scattering incident light.

17. A transmissive liquid crystal display device or transflective liquid crystal display device, wherein said display panel, said transparent/scattering switching element, said louver, and said backlight are arranged in the following sequence from the direction of an observer: display panel, transparent/scattering switching element, louver, backlight.

18. A terminal device comprising the display device according to claim 3.

19. The terminal device according to claim 18, wherein a direction in which said light-direction regulating element regulates light rays is parallel to a straight line connecting both eyes of an observer, or is at an angle of 10 degrees or less in relation to a straight line connecting both eyes of an observer.

20. The terminal device according to claim 18, wherein said terminal device is a mobile telephone, a personal information terminal, a gaming device, a digital camera, a video camera, a video player, a notebook personal computer, a cash dispenser, or a vending machine.