Light transmitting and dispersing filter having low reflectance

• US 5,781,344 A
• Filed: 10/08/1996
• Issued: 07/14/1998
• Est. Priority Date: 09/03/1993
• Status: Expired due to Fees

• Current Assignee: Jenmar Visual Systems Incorporated
• Original Assignee: Jenmar Visual Systems Incorporated
• Inventors: Vance, Dennis W.
• Primary Examiner(s): NGUYEN, THONG Q
• Application Number:
  US08/729,803
• Time in Patent Office: 644 Days
• Field of Search: 359/443, 359/452-457, 359/601, 359/613, 359/615, 359/885-894, 359/900
• US Class Current: 359/614
• CPC Class Codes: C03C 12/00 Powdered glass C03C8/02 takes precedence; Bead compositions
• CPC Class Codes: G02B 5/0215 the surface having a regular structure
• CPC Class Codes: G02B 5/0257 creating an anisotropic diffusion characteristic, i.e. distributing output differently in two perpendicular axes
• CPC Class Codes: G02B 5/0278 used in transmission
• CPC Class Codes: G02B 5/206 comprising particles embedded in a solid matrix
• CPC Class Codes: G03B 21/625 Lenticular translucent screens

Abstract

Multi-layer light filters provide optimized gain control, contrast, and ambient light rejection through the addition of optical layers to a basic refraction light filter. These additional layers allow adjustment of the gain, contrast, and ambient light rejection of light filters in a substantially independent manner, and can be combined to simultaneously optimize these optical properties.

Claims

1. A light filter, comprising:

a light transmitting material having a front surface and a back surface;

a light absorbing layer of material having a front surface and a back surface, wherein the back surface of the light transmitting material is affixed to the front surface of the light absorbing layer of material;

a plurality of beads of light transmitting material arranged in a single-layer array, the beads being supported in the light absorbing layer of material, perforating the front surface of the light absorbing layer of material, and protruding through the back surface of the light absorbing layer of material; and

a layer of light transmitting material, having a selected thickness, affixed to the back surface of the light absorbing layer of material in interstices between the beads.

2. A light filter, comprising:

a light absorbing layer of material having a front surface and a back surface;

a plurality of beads of light transmitting material arranged in a single-layer array, the beads being supported in the light absorbing layer of material, perforating the front surface of the light absorbing layer of material, and protruding through the back surface of the light absorbing layer of material; and

a layer of light transmitting material, having a selected thickness, affixed to the back surface of the light absorbing layer of material.

3. A light filter, comprising:

a light absorbing layer of material having a front surface and a back surface;

a plurality of beads of light transmitting material arranged in a single-layer array, the beads being supported in the light absorbing layer of material, perforating the front surface of the light absorbing layer of material, and protruding through the back surface of the light absorbing layer of material;

a second light absorbing layer of material having a front surface affixed to the back surface of the first light absorbing layer of material, and having a back surface through which the beads protrude; and

a layer of light transmitting material, having a selected thickness, affixed to the back surface of the second light absorbing layer of material in interstices between the beads.

4. A light filter, comprising:

a light transmitting material having a front surface and a back surface;

a light absorbing layer of material having a front surface and a back surface, wherein the back surface of the light transmitting material is affixed to the front surface of the light absorbing layer of material;

a plurality of beads of light transmitting material arranged in a single-layer array, the beads being supported in the light absorbing layer of material, perforating the front surface of the light absorbing layer of material, and protruding through the back surface of the light absorbing layer of material;

a second light absorbing layer of material having a front surface affixed to the back surface of the first light absorbing layer of material, and having a back surface through which the beads protrude; and

a layer of light transmitting material, having a selected thickness, affixed to the back surface of the second light absorbing layer of material.

5. A light filter, comprising:

a light transmitting material having a front surface and a back surface;

a light absorbing layer of material having a front surface and a back surface, wherein the back surface of the light transmitting material is affixed to the front surface of the light absorbing layer of material;

a plurality of beads of light transmitting material arranged in a single-layer array, the beads being supported in the light absorbing layer of material, perforating the front surface of the light absorbing layer of material, and protruding through the back surface of the light absorbing layer of material; and

a second light absorbing layer of material having a front surface affixed to the back surface of the first light absorbing layer of material, and having a back surface through which the beads protrude.

6. A light filter, comprising:

a light absorbing layer of material having a front surface and a back surface;

a plurality of beads of light transmitting material arranged in a single-layer array, the beads being supported in the light absorbing layer of material, perforating the front surface of the light absorbing layer of material, and protruding through the back surface of the light absorbing layer of material; and

a second light absorbing layer of material having a front surface affixed to the back surface of the first light absorbing layer of material, and having a back surface through which the beads protrude.

7. A light filter, comprising:

a light absorbing layer of material with a front surface and a back surface, wherein the material in the layer is highly transmissive near the front surface and lowly transmissive near the back surface; and

a plurality of beads of light transmitting material arranged in a single-layer array, the beads partially embedded within and held together by the light absorbing layer of material so as to perforate the front surface and protrude through the back surface, for providing light transmitting channels through the light absorbing layer of material.

8. The light filter of claim 7, wherein:

the light absorbing layer of material includes a support sheet containing perforations, with the beads of light transmitting material bonded into the perforations of the support sheet for supporting the beads in the single-layer array.

9. The light filter of claim 8, wherein:

the support sheet comprises a mesh of spaced and intersecting fibers forming the perforations in the regions between the fibers.

10. The light filter of claim 8, wherein:

the support sheet comprises a metallic sheet containing perforations.

11. The light filter of claim 8, wherein:

the support sheet has a front face and a back face, and the perforations in the support sheet extend from the front face to the back face;

the beads of light transmitting material are affixed into the perforations of the support sheet at the back face creating depressions between the beads and the front face; and

the depressions are filled with light transmitting material.

12. The light filter of claim 11, additionally comprising:

a layer of light transmitting material with a back face affixed to the front face of the support sheet; and

wherein

the light transmitting material filling the depressions comprises a non-solid material trapped between the beads, the support sheet, and the layer of light transmitting material.

13. The light filter of claim 7, wherein:

the light absorbing layer of material comprises a plurality of sheets having a front face and a back face, the sheets being stacked with the back face of one sheet in front of the front face of another sheet, and the sheets affixed together to form the layer.

14. The light filter of claim 13, wherein:

the plurality of sheets includes a sheet of light transmitting material for increasing the transmissivity of the light filter.

15. The light filter of claim 13, wherein:

the plurality of sheets includes at least one sheet of photosensitive film for varying the transmissivity of the light absorbing layer of material in response to exposure of the light filter to light.

16. A light filter, comprising:

a light absorbing layer of material with a front surface and a back surface;

a plurality of beads of light transmitting material arranged in a single-layer array, the beads partially embedded within and held together by the light absorbing layer of material so as to perforate the front surface and protrude through the back surface, for providing light transmitting channels through the light absorbing layer of material; and

wherein

at least one from the group of the light absorbing layer of material and the beads of light transmitting material includes a material of adjustable transmissivity for adjusting the transmissivity of the light filter.

17. The light filter of claim 16, wherein:

the material of adjustable transmissivity includes photochromic material for adjusting the transmissivity of the light filter in response to exposure of the light filter to light.

18. The light filter of claim 16, wherein:

the material of adjustable transmissivity includes an electro-optically active material for adjusting the transmissivity of the light filter in response to exposure of the light filter to an electric field.

19. A light filter, comprising:

a light absorbing layer of material with a front surface and a back surface;

a plurality of beads of light transmitting material arranged in a single-layer array, the beads partially embedded within and held together by the light absorbing layer of material so as to perforate the front surface and protrude through the back surface, for providing light transmitting channels through the light absorbing layer of material; and

an additional layer of material of adjustable transmissivity bonded to at least one from the group of the front surface and the back surface of the light absorbing layer of material for adjusting the transmissivity of the light filter.

20. The light filter of claim 19, wherein:

the additional layer of material includes electro-optically active material for adjusting the transmissivity of the light filter in response to exposure of the light filter to an electric field.

21. The light filter of claim 19, wherein:

the additional layer of material includes photochromic material for adjusting the transmissivity of the light filter in response to exposure of the light filter to light.

22. A light filter comprising:

a light absorbing layer of material with a front surface and a back surface;

a plurality of beads of light transmitting material arranged in a single-layer array, the beads partially embedded within and held together by the light absorbing layer of material so as to perforate the front surface and protrude through the back surface, for providing light transmitting channels through the light absorbing layer of material; and

a plurality of smaller beads of light transmitting material positioned between the beads in the single-layer array, for increasing the packing density of beads in the light filter.

23. A method of manufacturing a light filter of light transmissive beads and optical materials including light absorbing material and light transmitting material using a support surface for supporting the light filter during manufacture, the method comprising the steps of:

depositing the light absorbing material over the support surface for forming a layer of light absorbing material;

spreading the light transmissive beads over the deposited material and arranging the light transmissive beads in an array;

penetrating the light transmissive beads into the deposited material substantially to the support surface;

depositing and fusing a selected quantity of additional optical material onto the layer of light absorbing material, the optical material from the group of light transmitting material and light absorbing material; and

removing the light filter including the light transmissive beads, layer of light absorbing material, and the additional optical material from the support surface.

24. The method of manufacturing a light filter of claim 23 additionally using a release agent for easing the removal of the light filter from the support surface, the method additionally comprising the step of:

coating the release agent over the support surface before depositing the light absorbing material over the support surface.

25. The method of manufacturing a light filter of claim 23 additionally including a light transmitting sheet as a front surface to the light filter, the method additionally comprising the steps of:

laying the light transmitting sheet over the support surface before depositing the light absorbing material over the support surface, the light transmitting sheet for forming the front surface of the light filter; and

removing the light filter including the light transmissive beads, the layer of light absorbing material, the light transmitting sheet, and the additional optical material from the support surface.

26. The method of manufacturing a light filter of claim 23, wherein the light absorbing material deposited over the support surface comprises thermoplastic material having a viscous fluid state and a substantially rigid set state, and wherein:

the plastic is softened prior to penetration of the light transmissive beads and set after penetration of the light transmissive beads.

27. A method of manufacturing a light filter of light transmissive beads and light absorbing material, the method using a support surface and electrical charges for supporting and arranging the light transmissive beads during manufacture, and comprising the steps of:

selectively electrically charging the light transmissive beads;

depositing the light transmissive beads on the support surface;

allowing the selective electrical charges to position the light transmissive beads on the support surface in a close packed array;

binding the light transmissive beads together with the light absorbing material; and

removing the light filter including the light transmissive beads and layer of light absorbing material from the support surface.

28. The method of manufacturing a light filter of claim 27 additionally including a light transmitting sheet as a front surface to the light filter, the method additionally comprising the steps of:

laying the light transmitting sheet over the support surface before selectively electrically charging the light transmissive beads; and

removing the light filter including the light transmissive beads, the layer of light absorbing material, and the light transmitting sheet from the support surface.

29. A method of manufacturing a light filter of light transmissive beads and a layer of light absorbing material using a template containing indentations for holding the light transmissive beads in an array during an embedding process, the method comprising the steps of:

positioning light transmissive beads into the indentations in the template;

embedding into the layer of light absorbing material the array of beads being supported in position by the template; and

removing the template, leaving the array of beads embedded in the layer of light absorbing material.