Surface light source device with polarization function

• US 5,982,540 A
• Filed: 03/13/1995
• Issued: 11/09/1999
• Est. Priority Date: 03/16/1994
• Status: Expired due to Term

• Current Assignee: Enplas Corporation
• Original Assignee: Enplas Corporation
• Inventors: Arai, Takayuki, Koike, Yasuhiro
• Primary Examiner(s): Shafer, Ricky D.
• Application Number:
  US08/403,323
• Time in Patent Office: 1,702 Days
• Field of Search: 359/40, 359/42, 359/48, 359/63, 359/487, 359/490, 359/494, 359/495, 385/146, 385/901, 385/33, 385/43, 385/129, 385/131, 362/26, 362/31, 362/19, 362/32, 349/62, 349/64, 349/65, 349/96
• US Class Current: 359/485.02
• CPC Class Codes: G02B 6/0001 specially adapted for lighting devices or systems lighting or signalling on vehicles using light guides B60Q1/00; lighting devices for vehicle dashboards B60Q3/10; lighting devices for vehicle interior using light guides B60Q3/62; lighting devices mounted on the vehicle rear part using light guides F21S43/235; measuring arrangements having light conducting pointers G01D13/265; illumination of liquid crystal displays G02F1/1336; illuminated signs G09F13/00
• 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 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• 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 6/0065 Manufacturing aspects; Material aspects
• CPC Class Codes: Y10S 385/901 Illuminating or display apparatus

Abstract

Light is supplied into a light incident surface 2 from a fluorescent lamp L enclosed by a silver foil sheet R, and parallelized illuminating light flux is taken out from a light exit surface 3. On a back surface 4 side of a light flux parallelizer 1, across or without a thin air layer 5, a polarization converter Ε is disposed. The polarization converter Ε reinforces the polarization function of the surface light source device through polarization conversion action accompanying reflection in the prism. At a position confronting the light exit surface 3 across an air layer 7, a polarization separating plate 8 is disposed. At a further outside, across an air layer 9, an exit light direction modifier 10 is disposed. A bright polarized illuminating light flux is emitted from a light exit surface 11. When applied to a backlight of a liquid crystal display, a liquid crystal display panel is disposed at a further outside of the exit light direction modifier 10.

Claims

1. A surface light source device with polarization function comprising:

a light flux parallelizer composed of a plate form light scattering light guide having a wedge shaped section, and light feed means disposed at the thicker end side of the light flux parallelizer, and

light permeable polarization separating means having reflection characteristic depending on polarization components, being disposed so as to extend along the light exit surface of the light flux parallelizer,

wherein the polarization separating means comprises a polarization separating plate having a refractive index in a range of 1.3 to 2.0, and a repetitive slope for approximately satisfying the Brewster'"'"'s angle condition for the exit direction of the parallel light flux emitted from the light exit surface of the light flux parallelizer is formed on the light incident surface of the polarization separating plate.

15. A surface light source device with polarization function according to any one of claims 1, 2 and 3-14 wherein the correlation distance "a" is in a range of 0.06 μ

m≦

a≦

35 μ

m when the correlation function γ

(r) of the refractive index non-uniform structure for providing the light scattering light guide with a light scatter capability is approximated by γ

(r)=exp (-r/a), where "r" is a distance between two points in the light scattering light guide.

2. A surface light source device with polarization function comprising:

a light flux parallelizer composed of a plate form light scattering light guide having a wedge shaped section, and light feed means disposed at the thicker end side of the light flux parallelizer,

light permeable polarization separating means having reflection characteristic depending on polarization components, being disposed so as to extend along the light exit surface of the light flux parallelizer, and

an exit light direction modifier disposed outside of the polarization separating means,

wherein the polarization separating means comprises a polarization separating plate having a refractive index in a range of 1.3 to 2.0, and

a repetitive slope for approximately satisfying the Brewster'"'"'s angle condition for the exit direction of the parallel light flux emitted from the light exit surface of the light flux parallelizer is formed on the light incident surface of the polarization separating plate.

3. A surface light source device with polarization function comprising:

a light flux parallelizer composed of a plate form light scattering light guide having a wedge shaped section, and light feed means disposed at the thicker end side of the light flux parallelizer,

light permeable polarization separating means having reflection characteristic depending on polarization components, being disposed so as to extend along the light exit surface of the light flux parallelizer, and

a polarization scrambler disposed along the surface at the side opposite to the light exit surface of the light flux parallelizer.

4. A surface light source device with polarization function comprising:

a light flux parallelizer composed of a plate form light scattering light guide having a wedge shaped section, and light feed means disposed at the thicker end side of the light flux parallelizer,

light permeable polarization separating means having reflection characteristic depending on polarization components, being disposed so as to extend along the light exit surface of the light flux parallelizer,

an exit light direction modifier disposed outside of the polarization separating means, and

a polarization scrambler disposed along the surface at the side opposite to the light exit surface of the light flux parallelizer.

5. A surface light source device with polarization function comprising:

a light flux parallelizer composed of a plate form light scattering light guide having a wedge shaped section, and light feed means disposed at the thicker end side of the light flux parallelizer,

light permeable polarization separating means having reflection characteristic depending on polarization components, being disposed so as to extend along the light exit surface of the light flux parallelizer, and

polarization converting means disposed along the surface at the side opposite to the light exit surface of the light flux parallelizer,

wherein the polarization converting means possesses a phase difference plate and light reflecting means disposed outside of the phase difference plate.

6. A surface light source device with polarization function comprising:

a light flux parallelizer composed of a plate form light scattering light guide having a wedge shaped section, and light feed means disposed at the thicker end side of the light flux parallelizer,

light permeable polarization separating means having reflection characteristic depending on polarization components, being disposed so as to extend along the light exit surface of the light flux parallelizer,

an exit light direction modifier disposed outside of the polarization separating means, and

polarization converting means disposed along the surface at the side confronting the light exit surface of the light flux parallelizer,

wherein the polarization converting means possesses a phase difference plate and light reflecting means disposed outside of the phase difference plate.

7. A surface light source device with polarization function comprising:

a light flux parallelizer composed of a plate form light scattering light guide having a wedge shaped section, and light feed means disposed at the thicker end side of the light flux parallelizer,

light permeable polarization separating means having reflection characteristic depending on polarization components, being disposed so as to extend along the light exit surface of the light flux parallelizer, and

polarization converting means disposed along the surface at the side opposite to the light exit surface of the light flux parallelizer,

wherein the polarization converting means comprises a region disposing parallel a multiplicity of compound prism regions in one body shape sequentially uniting three triangular columnar volume region elements having both ends in right-angled isosceles triangular form so that axial directions of triangular columns corresponding to said elements respectively may be directed in three mutually orthogonal directions.

8. A surface light source device with polarization function comprising:

a light flux parallelizer composed of a plate form light scattering light guide having a wedge shaped section, and light feed means disposed at the thicker end side of the light flux parallelizer,

light permeable polarization separating means having reflection characteristic depending on polarization components, being disposed so as to extend along the light exit surface of the light flux parallelizer,

an exit light direction modifier disposed outside of the polarization separating means, and

polarization converting means disposed along the surface at the side opposite to the light exit surface of the light flux parallelizer,

wherein the polarization converting means comprises a region disposing parallel a multiplicity of compound prism regions in one body shape sequentially uniting three triangular columnar volume region elements having both ends in right-angled isosceles triangular form so that axial directions of triangular columns corresponding to said elements respectively may be directed in three mutually orthogonal directions.

9. A surface light source device with polarization function comprising:

a light flux parallelizer composed of a plate form light scattering light guide having a wedge shaped section, and light feed means disposed at the thicker end side of the light flux parallelizer,

light permeable polarization separating means having reflection characteristic depending on polarization components, being disposed so as to extend along the light exit surface of the light flux parallelizer, and

polarization converting means disposed along the surface at the side opposite to the light exit surface of the light flux parallelizer,

wherein the polarization converting means comprises a region disposing parallel a multiplicity of compound prism regions in one body shape coupling parallel a plurality of unit volume regions, of which unit volume region is a volume region having one body shape sequentially uniting three triangular columnar volume region elements having both ends in right-angled isosceles triangular form so that axial directions of triangular columns corresponding to said elements respectively may be directed in three mutually orthogonal directions.

10. A surface light source device with polarization function comprising:

a light flux parallelizer composed of a plate form light scattering light guide having a wedge shaped section, and light feed means disposed at the thicker end side of the light flux parallelizer,

light permeable polarization separating means having reflection characteristic depending on polarization components, being disposed so as to extend along the light exit surface of the light flux parallelizer,

an exit light direction modifier disposed outside of the polarization separating means, and

polarization converting means disposed along the surface at the side opposite to the light exit surface of the light flux parallelizer,

wherein the polarization converting means comprises a region disposing parallel a multiplicity of compound prism regions in one body shape coupling parallel a plurality of unit volume regions, of which unit volume region is a volume region having one body shape sequentially uniting three triangular columnar volume region elements having both ends in right-angled isosceles triangular form so that axial directions of triangular columns corresponding to said elements respectively may be directed in three mutually orthogonal directions.

11. A surface light source device with polarization function comprising:

a light flux parallelizer composed of a plate form light scattering light guide having a wedge shaped section, and light feed means disposed at the thicker end side of the light flux parallelizer,

light permeable polarization separating means having reflection characteristic depending on polarization components, being disposed so as to extend along the light exit surface of the light flux parallelizer, and

polarization converting means disposed along the surface at the side opposite to the light exit surface of the light flux parallelizer,

wherein the polarization converting means comprises a region disposing parallel a multiplicity of compound prism regions in one body shape coupling parallel a plurality of unit volume regions, of which unit volume region is a volume region having one body shape sequentially uniting three triangular columnar volume region elements having both ends in right-angled isosceles triangular form so that axial directions of triangular columns corresponding to said elements respectively may be directed in three mutually orthogonal directions, and a substrate region made of an optical material repetitively forming slopes on both surface and back sides, and

the compound prism region is provided on the repetitive slope on one side of the surface and back sides, and is coupled with the substrate region optically and mechanically.

12. A surface light source device with polarization function comprising:

a light flux parallelizer composed of a plate form light scattering light guide having a wedge shaped section, and light feed means disposed at the thicker end side of the light flux parallelizer,

light permeable polarization separating means having reflection characteristic depending on polarization components, being disposed so as to extend along the light exit surface of the light flux parallelizer,

an exit light direction modifier disposed outside of the polarization separating means, and

polarization converting means disposed along the surface at the side opposite to the light exit surface of the light flux parallelizer,

wherein the polarization converting means comprises a region disposing parallel a multiplicity of compound prism regions in one body shape coupling parallel a plurality of unit volume regions, of which unit volume region is a volume region having one body shape sequentially uniting three triangular columnar volume region elements having both ends in right-angled isosceles triangular form so that axial directions of triangular columns corresponding to said elements respectively may be directed in three mutually orthogonal directions, and a substrate region made of an optical material repetitively forming slopes on both surface and back sides, and

the compound prism region is provided on the repetitive slope on one side of the surface and back sides, and is coupled with the substrate region optically and mechanically.

13. A surface light source device with polarization function comprising:

a light flux parallelizer composed of a plate form light scattering light guide having a wedge shaped section, and light feed means disposed at the thicker end side of the light flux parallelizer,

light permeable polarization separating means having reflection characteristic depending on polarization components, being disposed so as to extend along the light exit surface of the light flux parallelizer, and

polarization converting means disposed along the surface at the side opposite to the light exit surface of the light flux parallelizer,

wherein the polarization converting means comprises a region disposing parallel a multiplicity of compound prism regions in one body shape coupling parallel a plurality of unit volume regions, of which unit volume region is a volume region having one body shape sequentially uniting three triangular columnar volume region elements having both ends in right-angled isosceles triangular form so that axial directions of triangular columns corresponding to said elements respectively may be directed in three mutually orthogonal directions, and a substrate region made of an optical material repetitively forming slopes on one of the surface and back sides and forming a flat plane on the other side, and

the compound prism region is provided on the repetitive slope side, and is coupled with the substrate region optically and mechanically.

14. A surface light source device with polarization function comprising:

a light flux parallelizer composed of a plate form light scattering light guide having a wedge shaped section, and light feed means disposed at the thicker end side of the light flux parallelizer,

light permeable polarization separating means having reflection characteristic depending on polarization components, being disposed so as to extend along the light exit surface of the light flux parallelizer,

an exit light direction modifier disposed outside of the polarization separating means, and

polarization converting means disposed along the surface at the side confronting the light exit surface of the light flux parallelizer,

wherein the polarization converting means comprises a region disposing parallel a multiplicity of compound prism regions in one body shape coupling parallel a plurality of unit volume regions, of which unit volume region is a volume region having one body shape sequentially uniting three triangular columnar volume region elements having both ends in right-angled isosceles triangular form so that axial directions of triangular columns corresponding to said elements respectively may be directed in three mutually orthogonal directions, and a substrate region made of an optical material repetitively forming slopes on one of the surface and back sides and forming a flat plane on the other side, and

the compound prism region is provided on the repetitive slope side, and is coupled with the substrate region optically and mechanically.

16. A surface light source device with polarization function comprising:

a light flux parallelizer composed of a plate form light scattering light guide having a wedge shaped section with a thicker end side and a light exit surface,

light feed means disposed at the thicker end side of the light flux parallelizer, and

light permeable polarization separating means having reflection characteristics depending on polarization components, positioned to extend along the light exit surface of the light flux parallelizer,

wherein the correlation distance "a" is in a range of 0.06 μ

m≦

a≦

35 μ

m when the correlation function γ

(r) of the refractive index non-uniform structure for providing the light scattering light guide with a light scatter capability is approximated by γ

(r)=exp (-r/a), where r is a distance between two points in the light scattering light guide.

17. A surface light source device with polarization function comprising:

a light flux parallelizer composed of a plate form light scattering light guide having a wedge shaped section with a thicker end side and a light exit surface,

light feed means disposed at the thicker end side of the light flux parallelizer,

light permeable polarization separating means having reflection characteristics depending on polarization components, positioned to extend along the light exit surface of the light flux parallelizer, and

a light exit direction modifier disposed outside of the polarization separating means,

wherein the correlation distance "a" is in a range of 0.06 μ

m≦

a≦

35 μ

m when the correlation function γ

(r) of the refractive index non-uniform structure for providing the light scattering light guide with a light scatter capability is approximated by γ

(r)=exp (-r/a), where r is a distance between two points in the light scattering light guide.