Backlighting device

• US 6,144,424 A
• Filed: 12/05/1996
• Issued: 11/07/2000
• Est. Priority Date: 12/05/1995
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Okuda, Eiichiro, Okauchi, Tohru, Asakawa, Shiro
• Primary Examiner(s): Parker, Kenneth
• Application Number:
  US08/760,711
• Time in Patent Office: 1,433 Days
• Field of Search: 349/11, 349/65, 349/64, 349/62, 349/112, 362/26, 362/31, 385/146, 385/129, 385/901, 379/113
• US Class Current: 349/65
• CPC Class Codes: B60K 35/22 Display screens
• CPC Class Codes: B60K 35/53 Movable instruments, e.g. slidable
• CPC Class Codes: G01C 21/265 constructional aspects of navigation devices, e.g. housings, mountings, displays G01C21/3688 takes precedence
• CPC Class Codes: G01C 21/365 Guidance using head up displays or projectors, e.g. virtual vehicles or arrows projected on the windscreen or on the road itself
• CPC Class Codes: G02B 2027/0118 comprising devices for improving the contrast of the display / brillance control visibility
• CPC Class Codes: G02B 2027/0154 with movable elements
• CPC Class Codes: G02B 2027/0159 with mechanical means other than scaning means for positioning the whole image
• CPC Class Codes: G02B 27/0101 characterised by optical features G02B27/0172 takes precedence
• CPC Class Codes: G02B 5/30 Polarising elements light-modulating devices with active elements G02F1/00
• CPC Class Codes: G02B 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• 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 6/0051 Diffusing 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: G02B 6/006 to produce indicia, symbols, texts or the like
• CPC Class Codes: G02B 6/0065 Manufacturing aspects; Material aspects
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/134309 characterised by their geometrical arrangement
• CPC Class Codes: G02F 1/1345 Conductors connecting electrodes to cell terminals
• CPC Class Codes: G02F 1/13476 in which at least one liquid crystal cell or layer assumes a scattering state
• CPC Class Codes: Y10S 385/901 : Illuminating or display apparatus

Abstract

To achieve a backlighting device having excellent light utilization, there is provided an edge lighting-type backlight having a light guiding member, a high-refractive-index layer formed thereon and having a higher refractive index than the light guiding member, and a scattering layer formed on the high-refractive-index layer. Light from a light source disposed facing the edge of the light guiding member enters the high-refractive-index layer through the light guiding member, and effectively scatters scatterers to produce high brightness, and furthermore, to achieve a color display device that eliminates color mixing in a transparent display device for decorative or various display uses, a construction is provided in which on one surface of a light guiding plate there are formed a high-refractive-index layer having a higher refractive index than the light guiding plate, a light scattering layer, and a low-refractive-index layer having a lower refractive index than the light guiding plate, one on top of another in this order, and on-top of that structure another light guiding plate is provided, on top of which a high-refractive-index layer and a light scattering layer are likewise formed, while a color filter is disposed on one edge face of each light guiding plate and a light source is disposed near each color filter.

Claims

1. A backlighting device comprising:

a light guiding plate having a light emergence surface, a bottom surface and a light receiving edge;

light source means disposed facing said edge of said light guiding plate;

a substantially transparent layer having a higher refractive index than said light guiding plate disposed on top of and immediately adjacent said light emergence surface of said light guiding plate; and

a scattering layer disposed on top of said substantially transparent layer wherein the bottom surface is free of an attached reflecting layer.

2. A backlighting device according to claim 1, wherein the refractive index of said higher-refractive-index layer is 0.05 to 1.50 greater than the refractive index of said light guiding member.

3. A backlighting device according to claim 1, wherein said scattering layer comprises a mixture of two or more kinds of polymers that have different refractive indices and whose constituents are substantially transparent and are present in a phase separated state.

4. A backlighting device according to claim 1, wherein in said scattering layer a high-refractive-index compound is present in a phase separated state within a low-refractive-index polymer.

5. The backlighting device of claim 1 wherein said transparent layer is formed from T_i O₂.

6. The backlighting device of claim 1 wherein said transparent layer is in contact with said light guiding plate and said scattering layer is in contact with said transparent layer.

7. A backlighting device comprising:

a light guiding plate having a light emergence surface and a light receiving end face, the light emergence surface of said light guiding plate is sloped with a sloping angle which is greater than or equal to 87 degrees and less than 90 degrees with respect to the end face;

light source means disposed facing said end face of said light guiding plate;

a substantially transparent layer having a higher refractive index than said light guiding plate disposed on top of and immediately adjacent said light emergence surface of said light guiding plate; and

a scattering layer disposed on top of the substantially transparent layer;

wherein the scattering layer has a slope that is substantially the same as the slope of the light emergence surface.

8. The backlighting device of claim 7 including

a substantially transparent layer having a higher refractive index than the light guiding plate disposed between the light emergence surface and the scattering layer;

and

wherein the transparent layer is formed from S_n O₂.

9. A backlighting device comprising

a light guiding plate having a light emergence surface, a bottom surface and a light receiving edge, wherein said light emergence surface is nearer to a viewer than the bottom surface of the light guiding plate;

light source means disposed facing said edge;

a substantially transparent layer having a higher refractive index than said light guiding plate disposed on top of and immediately adjacent said light emergence surface of said light guiding plate; and

a scattering layer disposed on top of said substantially transparent layer, wherein said scattering layer includes two or more kinds of materials having different refractive indices and having substantially no absorption bands within the visible spectral region mixed in a phase separated state and wherein the bottom surface is free of an attached reflecting layer.