Prismatic light-guide plate and illumination device that enable the provision of good-quality planar light source

Abstract

A prismatic light-guide plate has a prismatic surface, which is provided with a plurality of prisms that reflect light that is incident from a light-incident end thereof, and an emission surface opposite to the prismatic surface, which completely reflects the light that is incident thereto to propagate the same, and which also emits emitted light that is reflected from the prisms. The prismatic light-guide plate has scattering portions provided in a region of the emission surface that emits the emitted light at a high density, for scattering the emitted light and broadening an angle of view of light.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more clearly understood from the description of the preferred embodiments as set forth below with reference to the accompanying drawings, wherein:

FIG. 1 is a schematic perspective view of an example of an illumination device to which the present invention is applied;

FIG. 2 is a schematic perspective view of another example of an illumination device to which the present invention is applied;

FIG. 3 is a schematic perspective view of a further example of an illumination device to which the present invention is applied;

FIG. 4 is schematically illustrative of the propagation of light in a prismatic light-guide plate;

FIG. 5 is schematically illustrative of the convergence of light in the prismatic light-guide plate;

FIG. 6 is illustrative of the propagation positions and field-of-view characteristics of emitted light of the prismatic light-guide plate;

FIG. 7 shows light-emitting areas of the prismatic light-guide plate in detail;

FIG. 8 shows the emission of light from the prismatic light-guide plate;

FIG. 9 is an enlarged view of an example of a liquid-crystal panel;

FIG. 10 is illustrative of emitted light from a display device (liquid-crystal module) that uses the prismatic light-guide plate;

FIG. 11 is illustrative of emitted light when the prismatic light-guide plate and the liquid-crystal module are in a suitable positional relationship;

FIG. 12 is illustrative of emitted light when the prismatic light-guide plate and the liquid-crystal module are not in a suitable positional relationship;

FIG. 13 is illustrative of a first embodying example of a prismatic light-guide plate in accordance with the present invention;

FIG. 14 is illustrative of an example of a prior-art prismatic light-guide plate corresponding to FIG. 13;

FIGS. 15A and 15B are perspective views of the entire scattering portion of a first embodying example of the prismatic light-guide plate in accordance with the present invention;

FIG. 16 is a schematic view of a second embodying example of a prismatic light-guide plate in accordance with the present invention;

FIG. 17 is a schematic view of a third embodying example of a prismatic light-guide plate in accordance with the present invention;

FIG. 18 is a schematic view of a fourth embodying example of a prismatic light-guide plate in accordance with the present invention;

FIGS. 19A and 19B are perspective views of the entire scattering portion of the fourth embodying example of the prismatic light-guide plate in accordance with the present invention;

FIG. 20 is a schematic perspective view of a fifth embodying example of a prismatic light-guide plate in accordance with the present invention;

FIG. 21 is a schematic perspective view of a sixth embodying example of a prismatic light-guide plate in accordance with the present invention;

FIG. 22 is a schematic perspective view of a seventh embodying example of a prismatic light-guide plate in accordance with the present invention;

FIG. 23 is a schematic perspective view of a eighth embodying example of a prismatic light-guide plate in accordance with the present invention;

FIG. 24 is schematically illustrative of an embodying example of an illumination device in accordance with the present invention;

FIG. 25 is illustrative of scattering portions in the illumination device of FIG. 24;

FIG. 26 is schematically illustrative of light scattering by a prismatic light-guide plate in accordance with the present invention;

FIG. 27 illustrates the theory of light scattering by a prismatic light-guide plate in accordance with the present invention;

FIG. 28 is illustrative of simulation models of prismatic light-guide plates in accordance with the present invention;

FIG. 29 shows simulation results of the output of luminosity distribution and emission angle obtained by the simulation models shown in FIG. 28;

FIG. 30 shows further simulation results of the output of luminosity distribution and emission angle obtained by the simulation models shown in FIG. 28;

FIG. 31 is schematically illustrative of a ninth embodying example of a prismatic light-guide plate in accordance with the present invention;

FIG. 32 is an enlargement of a scattering portion for the prismatic light-guide plate shown in FIG. 31;

FIG. 33 is a schematic perspective view of a mobile phone that is an example of an electronic device to which the present invention can be applied; and

FIG. 34 schematically shows the outer surface of the movable side of the mobile phone of FIG. 33.

Claims

1. A prismatic light-guide plate having a prismatic surface, which is provided with a plurality of prisms that reflect light that is incident from a light-incident end thereof, and an emission surface opposite to said prismatic surface, which completely reflects said light that is incident thereto to propagate the same, and which also emits emitted light that is reflected from said prisms, comprising: scattering portions provided in a region of said emission surface that emits said emitted light at a high density, for scattering said emitted light and broadening an angle of view of light.

2. The prismatic light-guide plate as claimed in claim 1, wherein said prisms are formed in bands at a predetermined spacing on said prismatic surface.

3. The prismatic light-guide plate as claimed in claim 2, wherein said scattering portions are provided to correspond to said predetermined spacing at which said prisms are provided.

4. The prismatic light-guide plate as claimed in claim 3, wherein said scattering portions are provided in correspondence with aperture portions of a black matrix of a display unit.

5. The prismatic light-guide plate as claimed in claim 4, wherein said scattering portions are formed to include at least one aperture portion of said black matrix of said display unit.

6. The prismatic light-guide plate as claimed in claim 3, wherein each of said scattering portions comprises a convex prism shape.

7. The prismatic light-guide plate as claimed in claim 3, wherein each of said scattering portions comprises a convex cone shape.

8. The prismatic light-guide plate as claimed in claim 3, wherein each of said scattering portions comprises a concave prismatic groove shape.

9. The prismatic light-guide plate as claimed in claim 3, wherein each of said scattering portions comprises a concave cone shape.

10. The prismatic light-guide plate as claimed in claim 3, wherein each of said scattering portions comprises a flattened ridge portion.

11. The prismatic light-guide plate as claimed in claim 3, wherein each of said scattering portions comprises a shape where a light-incident end side of said prismatic light-guide plate is small and a non-light-incident end side thereof is large.

12. The prismatic light-guide plate as claimed in claim 3, wherein each of said scattering portions comprises a distribution density where a light-incident end side of said prismatic light-guide plate is low density and a non-light-incident end side thereof is high density.

13. The prismatic light-guide plate as claimed in claim 1, wherein said scattering portions are formed integrally with said prismatic light-guide plate.

14. The prismatic light-guide plate as claimed in claim 1, wherein said scattering portions are formed on a scattering portion formation sheet that is separate from said prismatic light-guide plate, and said scattering portion formation sheet is integrated with said prismatic light-guide plate by attachment to said prismatic light-guide plate.

15. An illumination device including a light source and a prismatic light-guide plate, wherein: said prismatic light-guide plate has a prismatic surface, which is provided with a plurality of prisms that reflect light that is incident from a light-incident end thereof, and an emission surface opposite to said prismatic surface, which completely reflects said light that is incident thereto to propagate the same, and which also emits emitted light that is reflected from said prisms, wherein said prismatic light-guide plate comprises:scattering portions provided in a region of said emission surface that emits said emitted light at a high density, for scattering said emitted light and broadening an angle of view of light.

16. The illumination device as claimed in claim 15, further comprising a light-conducting member that converts light from said light source that is a point light source into a linear beam of light, and supplies the same to said prismatic light-guide plate.

17. An electronic device comprising an illumination device including a light source and a prismatic light-guide plate, wherein: said prismatic light-guide plate has a prismatic surface, which is provided with a plurality of prisms that reflect light that is incident from a light-incident end thereof, and an emission surface opposite to said prismatic surface, which completely reflects said light that is incident thereto to propagate the same, and which also emits emitted light that is reflected from said prisms, wherein said prismatic light-guide plate comprises:scattering portions provided in a region of said emission surface that emits said emitted light at a high density, for scattering said emitted light and broadening an angle of view of light.

18. The electronic device as claimed in claim 17, wherein: said illumination device is provided with a first illumination device provided on one display surface of said display panel and a second illumination device provided on another display surface of said display panel; andan image on said one display surface is displayed by light emitted from said second illumination device and also an image on said other display surface is displayed by light emitted from said first illumination device.

19. The electronic device as claimed in claim 18, wherein said display panel is a transmissive liquid-crystal display panel.

20. The electronic device as claimed in claim 17, wherein said electronic device is a clamshell-type mobile phone and the configuration is such that images displayed on said display panel are displayed by switching said first and second illumination devices for display on either the front or back of a movable side portion.