Illuminating system

• US 20010019479A1
• Filed: 01/26/2001
• Published: 09/06/2001
• Est. Priority Date: 05/13/1997
• Status: Active Grant

• Current Assignee: Atsushi Fukui, Hiroshi Watanabe, Kanji Nishii, Ken Tatsuta, Koki Nakabayashi
• Original Assignee: Atsushi Fukui, Hiroshi Watanabe, Kanji Nishii, Ken Tatsuta, Koki Nakabayashi
• Inventors: Nakabayashi, Koki, Nishii, Kanji, Tatsuta, Ken, Watanabe, Hiroshi, Fukui, Atsushi
• Granted Patent: US 6,379,017 B2
• Time in Patent Office: Days
• US Class Current: 362/31
• CPC Class Codes: G02B 6/0018 Redirecting means on the surface of the light guide
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• 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 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• CPC Class Codes: G02B 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: G02B 6/0048 with stepwise taper
• CPC Class Codes: G02B 6/005 provided by one optical element, or plurality thereof, placed on the light output side of the light guide
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02F 1/133616 Front illuminating devices

Abstract

The illuminating system comprises a linear light source, and a light guide member with the light source placed beside a side face thereof, in which the top face and the bottom face of the light guide member are generally parallel to each other and in which slits made of a different material or air are arranged at specified intervals in the top face of the light guide member. Therefore, most of light propagating within the light guide member is totally reflected at the slits formed in the light guide member so as to be outputted from the light guide member, thereby illuminating a reflecting plate. Its reflected light is incident again on the light guide member and the resulting totally reflected light is transmitted to the observer'"'"'s side at places other than the slits, while the observer'"'"'s field of view is not obstructed at the slit portions.

Claims

1. An illuminating system comprising

a light source;

and

a transparent plate with the light source placed beside a side face thereof,

wherein a plurality of grooves filled with a layer having a refractive index different from a refractive index of the transparent plate are arranged at specified intervals in a surface or interior of the transparent plate.

2. An illuminating system according to

claim 1

, wherein a top face and a bottom face of the transparent plate are generally parallel to each other.

3. An illuminating system according to

claim 1

, wherein a condition of

θ

<

sin<sup>−

1</sup>(n₁/n)−

sin<sup>−

1</sup>{(1/n)sin(β

)}

is satisfied where n is the refractive index of the transparent plate, n₁ is the refractive index of a material as the layer that fills the grooves which are the slits, θ

is an angle formed by each of the slits and the top face of the transparent plate and β

is an angle of visibility of the illuminating system.

16. A reflection type liquid crystal display device which comprises:

the illuminating system according to

claim 1

, the transparent plate taking light from the light source through a side face thereof and projecting illumination light through a lower face thereof subjected to at least one of an anti-reflection treatment and a diffuse treatment; and

a reflection type liquid crystal panel having a surface of at least one substrate thereof processed through at least one of the anti-reflection treatment and the diffuse treatment,

wherein the surface of the substrate of the liquid crystal panel processed through at least one of the anti-reflection treatment and the diffuse treatment is arranged to confront a lower face of the transparent plate, so that the reflection type liquid crystal panel is observed from an upper face side of the transparent plate.

17. A reflection type liquid crystal display device which comprises:

the illuminating system according to

claim 1

, the transparent plate taking light from the light source through a side face thereof and projecting illumination light through a lower face thereof subjected to at least one of an anti-reflection treatment and a diffuse treatment;

a reflection type liquid crystal panel having a surface of at least one substrate thereof processed through at least either an anti-reflection treatment or a diffuse treatment; and

a touch panel having a surface processed through a diffuse treatment,

wherein the surface of the substrate of the liquid crystal panel processed through at least either the anti-reflection treatment or the diffuse treatment is arranged to confront the lower face of the transparent plate and at the same time, the touch panel is disposed to confront an upper face of the transparent plate, so that the reflection type liquid crystal panel is observed from an upper face side of the transparent plate.

18. A reflection type liquid crystal display device according to

claim 16

, wherein a haze value of the diffuse treatment provided to the surface of the substrate of the reflection type liquid crystal panel, the lower face of the transparent plate or the surface of the touch panel is set to be not larger than 20%.

19. A reflection type liquid crystal display device according to

claim 16

, wherein a transparent material or a sheet of the material which has approximately the same refractive index as that of a material of the transparent plate and that of the substrate of the reflection type liquid crystal panel is interposed between the lower face of the transparent plate and the reflection type liquid crystal panel.

20. A reflection type liquid crystal display device which comprises:

the illuminating system according to

claim 1

, the transparent plate taking light from the light source through a side face thereof and projecting illumination light from a lower face thereof; and

a reflection type liquid crystal panel having an field angle control plate arranged on an upper face thereof, said control plate featuring a diffuse characteristic in one direction while being transparent in other directions,

wherein the face of the reflection type liquid crystal panel where the field angle control plate is arranged is set to confront the lower face of the transparent plate, and moreover an angle of the illumination light projected from the lower face of the transparent plate is almost agreed with a diffusion direction of the field angle control plate, so that the reflection type liquid crystal panel is observed from an upper face side of the transparent plate.

21. A reflection type liquid crystal display device according to

claim 20

, wherein an output angle of the transparent plate and the diffusion direction of the field angle control plate is 30-50°

to a normal direction of the reflection type liquid crystal panel.

22. An illuminating system according to

claim 1

, wherein the light house is a group of point light sources in which point light sources are arranged on an almost straight line via a constant interval to radiate in nearly the same direction,

the illuminating system further comprising:

a reflector having an opening part and disposed to cover the group of point light sources; and

a diffusing plate set at the opening part of the reflector,

wherein the diffusing plate is separated from the group of point light sources so that quantity of light from a center of an illuminance distribution by the point light source on the diffusing plate is nearly equal to that between centers of illuminance distributions of the point light sources.

23. An illuminating system according to

claim 22

, wherein the reflector is L-shaped so as not to directly pass light emitted from the point light sources to the diffusing plate.

24. An illuminating system according to

claim 22

, which further comprises a light guide member which outputs light entering from a side face thereof after emitted from the diffusing plate arranged at the opening part of the reflector of the linear light source, from a lower face side thereof by grooves formed in a lower face or an upper face thereof.

4. An illuminating system comprising:

a light source;

a transparent first plate with the light source placed beside a side face thereof; and

a transparent second plate placed on a top face of the first plate,

wherein a bottom face of the first plate is a plane surface and a plurality of stepwise slopes are arranged at specified intervals in the top face of the first plate;

in a bottom face of the second plate, stepwise slopes are arranged so as to be identical in configuration to the slopes of the top face of the first plate; and

the top face of the first plate and the bottom face of the second plate are placed with a specified spacing.

5. An illuminating system according to

claim 4

, wherein a condition of

θ

<

sin<sup>−

1</sup>(n₂/n)−

sin<sup>−

1</sup>{(1/n)sin(β

)}

is satisfied where n is the refractive index of the first plate, n₂ is the refractive index of a material as the layer bonding the first plate and the second plate to each other, θ

is an angle of each of the slopes of the top face of the first plate and the bottom face of the second plate and β

is an angle of visibility of the illuminating system.

6. An illuminating system according to

claim 5

, wherein a light outgoing angle of a collimator placed at an outgoing exit of the light source is within ±

sin<sup>−

1</sup>[n×

sin{90−

θ

−

sin<sup>−

1</sup>(n₂/n)}].

7. An illuminating system by overhead irradiation comprising:

a light source;

a transparent plate which is a light guide member in which a plurality of grooves are arranged in a top face of the light guide member at specified intervals in a direction parallel to a longitudinal direction of the light source, and in which a flat portion constituting a part of the top face is arranged between adjacent ones of the grooves, wherein an illumination object placed on a bottom face side of the light guide member is observed from a top face side of the light guide member.

8. An illuminating system by overhead irradiation according to

claim 7

, wherein each of the grooves of the light guide member is a V-shaped groove having a first slope located on one side closer to the light source and a second slope located on the other side farther from the light source, and wherein an angle θ

₁ formed by the first slope and the bottom face of the light guide member falls within a range of θ

₁≦

90°

−

θ

_c+2θ

₃, where θ

_c is a total reflection angle of the light guide member and θ

₃ is an angle formed by the flat portion and the bottom face of the light guide member.

9. An illuminating system by overhead irradiation according to

claim 7

, wherein each of the grooves of the light guide member is a V-shaped groove having a first slope located on one side closer to the light source and a second slope located on the other side farther from the light source, and wherein an angle θ

₁ formed by the first slope and the bottom face of the light guide member satisfies a condition of;

θ

₁≈

45+θ

₃−

(½

)sin<sup>−

1</sup>(1/n×

sinβ

), where n is a refractive index of the light guide member, θ

₃ is an angle formed by the flat portion and the bottom face of the light guide member and β

is an angle formed by a perpendicular of the bottom face of the light guide member and a direction of the observer.

10. An illuminating system by overhead irradiation according to

claim 7

, wherein each of the grooves of the light guide member is a V-shaped groove having a first slope located on one side closer to the light source and a second slope located on the other side farther from the light source, and wherein an angle θ

₂ formed by the second slope and the bottom face of the light guide member satisfies a condition of θ

₂≦

(½

)sin<sup>−

1</sup>(1/n), where n is a refractive index of the light guide member.

11. An illuminating system by overhead irradiation according to

claim 7

, wherein in the light guide member, a pitch of the grooves is not more than a dot pitch of the illumination object.

12. An illuminating system by overhead irradiation according to

claim 7

, wherein each of the grooves of the light guide member is a V-shaped groove having a first slope located on one side closer to the light source and a second slope located on the other side farther from the light source, and wherein in the light guide member, a length of the first slope is not more than {L×

(0.5/60)×

_π

/180}, where L is a distance between the top face of the light guide member and an observer observing the illumination object.

13. An illuminating system by overhead irradiation according to

claim 7

, wherein a transparent prism sheet is placed on the top face of the light guide member, the prism sheet having, with respect to a cross-sectional shape, a plurality of projected portions having slopes of an angle θ

₄ to the top face are arranged on the bottom face so that a flat portion generally parallel to the bottom face is interposed therebetween.

14. An illuminating system by overhead irradiation according to

claim 13

, wherein the length of the slope of the prism sheet is not more than {L×

(0.5/60)×

_π

/180}, where L is the distance between the observer who observes the illumination object and the top face of the light guide member.

15. An illuminating system comprising:

a light source; and

a transparent plate taking light from the light source through a side face thereof and projecting illumination light through a lower face thereof subjected to at least one of an anti-reflection treatment and a diffuse treatment,

wherein an illumination object which is disposed at a lower face side of the transparent plate is observed from an upper face side of the transparent plate.