Optical display

• US 5,319,491 A
• Filed: 08/10/1990
• Issued: 06/07/1994
• Est. Priority Date: 08/10/1990
• Status: Expired due to Term

• Current Assignee: Rambus Inc.
• Original Assignee: Continental Typographics, Inc.
• Inventors: Selbrede, Martin G.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Lester, Evelyn A.
• Application Number:
  US07/565,481
• Time in Patent Office: 1,397 Days
• Field of Search: 359/34, 359/291, 359/454, 359/292, 385/30, 385/32, 385/901, 385/13, 340/702, 340/718, 340/719, 340/783, 340/701
• US Class Current: 359/291
• CPC Class Codes: G02B 6/00 Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
• CPC Class Codes: G02F 1/011 in optical waveguides, not otherwise provided for in this subclass
• CPC Class Codes: G02F 1/0131 based on photo-elastic effects, e.g. mechanically induced birefringence
• CPC Class Codes: G09F 9/30 in which the desired character or characters are formed by combining individual elements panels comprising a number of electrodes in a single cell controlling light arriving from an independent light source, e.g. electro-optical or magneto-optical cell, G02F1/00

Abstract

An optical display in which at least one pixel is selectively controlled to shutter light out of a light guidance substrate by violating the light guidance conditions of the medium, and in which a full color palette is provided by multiplexing the three additive primaries in relation to the inherent limitations of the human eye.

Claims

1. An optical shutter comprising:

(a) a light guidance substrate adapted to channel light, which light guidance substrate comprises a substantially integral piece of transparent, high-refractive-index dielectric; and

(b) guidance-defeating means disposed on said light guidance substrate, which guidance-defeating means is adapted selectively and by means of electrostatic attraction to violate the light guidance conditions for said light guidance substrate, thus coupling any channeled light out of said light guidance substrate.

2. The optical shutter of claim 1 in which said guidance-defeating means comprises:

(a) a translucent electrode disposed on said light guidance substrate;

(b) a translucent electret plane disposed within said light guidance substrate in parallel, spaced-apart relationship with said electrode, which electret imposes an electric field at said electrode; and

(c) means for selectively charging and discharging said electrode.

3. The optical shutter of claim 1 in which said light guidance substrate additionally comprises a first layer formed of a high-refractive-index elastomer and a second layer formed of a deformable dielectric, and in which said guidance-defeating means comprises:

(a) a translucent electrode disposed on said second layer of said light guidance substrate;

(b) a translucent electret plane disposed within said light guidance substrate in parallel, spaced-apart relationship with said electrode, which electret imposes an electric field in the region occupied by said electrode; and

(c) means for selectively charging and discharging said electrode.

4. The optical shutter of claim 1 in which said light guidance substrate comprises at least one pixel which further comprises:

(a) a plurality (n) of areal subdivisions having relative areal proportions of

space="preserve" listing-type="equation">2.sup.(n-1) ;

2.sup.(n-2) ;

. . . ;

2.sup.1 ;

2.sup.0, where n<

1;

(b) a plurality of pairs of interdigitated electrodes disposed such that each of said areal subdivisions contains at least one of said pairs of interdigitated electrodes; and

(c) means for selectively activating said pairs of interdigitated electrodes.

5. The optical shutter of claim 4 in which said pairs of electrodes describe a plane when quiescent, and in which said optical shutter further comprises an electret plane spaced apart from and parallel to said plane of said pair of electrodes.

6. The optical shutter of claim 1 in which said guidance-defeating means comprises means for selectively invoking the Becker effect.

7. The optical shutter of claim 1 in which said guidance-defeating means comprises means for impressing a diffraction grating onto the surface of said light guidance substrate.

8. The optical shutter of claim 7 in which said means for impressing a diffraction grating onto said light guidance substrate comprises:

(a) at least one pair of interdigitated electrodes disposed on said light guidance substrate; and

(b) means for selectively charging and discharging said pair of interdigitated electrodes.

9. The optical shutter of claim 1 in which said light guidance substrate additionally comprises a first layer formed of a high-refractive-index elastomer and a second layer formed of a deformable dielectric, and in which said guidance-defeating means comprises:

(a) a pair of parallel, translucent electrodes disposed on opposite surfaces of said second layer of said light guidance substrate; and

(b) means for selectively charging and discharging at least one of said electrodes.

10. The optical shutter of claim 1 in which said light guidance substrate additionally comprises a first layer formed of a high-refractive-index elastomer and a second layer formed of a deformable dielectric, and in which said guidance-defeating means comprises:

(a) a pair of parallel, translucent electrodes disposed on opposite surfaces of said second layer of said light guidance substrate;

(b) a translucent disk formed of a high-refractive-index elastomer having a refractive index approximately equal to that of said first layer, which disk is disposed on one of said electrodes; and

(c) means for selectively charging and discharging said electrodes.

11. An optical display comprising:

(a) a light source capable of outputting alternating pulses of red, green and blue light;

(b) a light guidance substrate, which light guidance substrate comprises a substantially integral piece of transparent, high-refractive-index dielectric, for channeling the output of said light source; and

(c) means for selectively shuttering the light out of the light guidance substrate.

12. The optical display of claim 11 in which said means for selectively shuttering the light out of said light guidance substrate includes a pixel which comprises a plurality (n) of areal subdivisions having relative areal proportions of

13. The optical display of claim 12 further comprising means responsive to binary-encoded instructions for selectively enabling one or more of said subdivisions.

14. The optical display of claim 13 in which said means responsive to binary-encoded instructions for selectively enabling one or more of said subdivisions comprises:

(a) means for decoding a binary word; and

(b) means responsive to said decoding means which means selectively enable or disable one or more of said pixel subdivisions.

15. The optical display of claim 12 in which said plurality of areal subdivisions each comprises:

(a) an interdigitated pair of electrodes which pair of electrodes describes a plane; and

(b) an electret plane spaced apart from and parallel to said plane of said pair of electrodes.

16. The optical display of claim 11 in which:

(a) said optical display bas an optical clock rate significantly faster than the temporal color resolution limit of the human eye;

(b) said light source is adapted to output continually alternating bursts of red, green, and blue light wherein each burst is of duration greater than or equal to said clock rate; and

(c) said means for selectively shuttering the light out of said light guidance substrate further comprises;

(1) an optical shutter the minimum cycle time of which is equal to said clock rate; and

(2) control means adapted to open said optical shutter a varying fractional proportion of the burst time of said light source.

17. The optical display of claim 16 in which said control means further comprises means for selectively opening said optical shutter for a set of n temporal durations, which durations have the binary proportions of 2⁰ :

2¹ ;

2² ;

2³ ;

. . . ;

2.sup.(n-1), so as to yield pulse-modulated intensity control of said respective bursts of red, green and blue light.

18. The optical display of claim 16 in which said optical shutter further comprises a set of n areal subdivisions, which areal subdivisions have the binary proportions of 2⁰ :

2¹ ;

2² ;

2³ ;

. . . ;

2.sup.(n-1), so as to yield pulse-modulated intensity control of said respective bursts of red, green and blue light.

19. The optical display of claim 11 in which said means for selectively shuttering the light out of said light guidance substrate further comprises means disposed on said surface of said light guidance substrate which means is adapted selectively to violate the light guidance conditions of said light guidance substrate.

20. A passive display device comprising:

(a) a light source which includes means for providing strobed bursts of alternating red, blue, and green light, in a continual cycle;

(b) a light guidance substrate adapted to channel light and disposed so as to channel light output by said light source;

(c) guidance-defeating means disposed on said light guidance substrate, which guidance-defeating means selectively deforms said light guidance substrate such that the light guidance conditions for said light guidance substrate are locally violated thus coupling light out of said light guidance substrate; and

(d) means for selectively electrically activating said guidance-defeating means whereby said optical shutter is open during controlled periods of time during each of the red, blue, and green portions of the continual strobe cycle.

21. The passive display device of claim 20 in which:

(a) said light guidance substrate comprises a first layer having a first refractive index and a second layer having a second refractive index, which first and second layers are disposed one above the other in parallel relationship; and

(b) said guidance-defeating means further comprises means for selectively applying a local electric field to said second layer of said light guidance substrate so as to change the refractive index of said second layer such that it approximates the refractive index of said first layer of said light guidance substrate, whereby light is coupled out of said light guidance substrate.

22. The passive display device of claim 20 in which:

(a) said passive display device additionally comprises an encapsulant layer disposed on said guidance-defeating means and having a second refractive index, which encapsulant layer and light guidance substrate are disposed one above the other in parallel relationship;

(b) said light guidance substrate has a first refractive index; and

(c) said guidance-defeating means further comprises means for selectively applying a local electric field to said second layer of said light guidance substrate so as to change the refractive index of said second layer such that it approximates the refractive index of said first layer of said light guidance substrate, whereby light is coupled out of said light guidance substrate.

23. The passive display device of claim 20 in which:

(a) said light guidance substrate comprises a first layer having a first refractive index and a second layer having a second refractive index, which first and second layers are disposed one above the other in parallel relationship; and

(b) said guidance-defeating means further comprises means for selectively applying localized compressive force to said second layer of said light guidance substrate so as to change the refractive index of said second layer such that it approximates the refractive index of said first layer of said light guidance substrate, whereby light is coupled out of said light guidance substrate.

24. The passive display device of claim 20 in which:

(a) said passive display device additionally comprises an encapsulant layer disposed on said guidance-defeating means and having a second refractive index, which encapsulant layer and light guidance substrate are disposed one above the other in parallel relationship;

(b) said light guidance substrate has a first refractive index; and

(c) said guidance-defeating means further comprises means for selectively applying localized compressive force to said second layer of said light guidance substrate so as to change the refractive index of said second layer such that it approximates the refractive index of said first layer of said light guidance substrate, whereby light is coupled out of said light guidance substrate.

25. An optical display comprising:

(a) a light guidance substrate having parallel first and second surfaces, which light guidance substrate comprises a substantially integral piece of transparent, high-refractive-index dielectric;

(b) a light source comprising red, green and blue lamps disposed within an elliptical reflector which reflector is disposes so as to reflect light emanating from said lamps into said light guidance substrate;

(c) an opaque throat aperture disposed rigidly between said light guidance substrate and said light source, which opaque throat aperture admits light from said light source only at angles such that the sine of any given angle is less than the height of said opaque throat aperture divided by the depth of said opaque throat aperture; and

(d) a plurality of pixels disposed on said first surface of said light guidance substrate.

26. The optical display of claim 25 in which each of said pixels comprises:

(a) an electret layer disposed within said light guidance substrate, parallel to and spaced-away from said first surface of said light guidance substrate; and

(b) eight cells disposed on said first surface of said light guidance substrate and having respective areas in the ratio 128;

64;

32;

16;

8;

4;

2;

1, each cell of which comprises a pair of interdigitated translucent electrodes.

27. The optical display of claim 25 in which each of said pixels comprises:

(a) an electret layer disposed on said first surface of said light guidance substrate;

(c) a clear elastomer layer disposed on said electret layer;

(c) a rigid, clear cover plate, which cover plate has a first surface, and which cover plate comprises on said first surface a plurality of translucent interdigitated electrodes; and

(d) eight cells disposed on said first surface of said cover plate and having respective areas in the ratio 128;

64;

32;

16;

8;

4;

2;

1, each cell of which comprises a pair of said interdigitated translucent electrodes.

28. The optical display of claim 25 in which:

(a) said optical display bas an optical clock rate significantly faster than the temporal color resolution limit of the human eye;

(b) said light source is adapted to output continually alternating bursts of red, green, and blue light wherein each burst is of duration equal to a multiple of said clock rate; and

(c) each of said pixels comprises;

(1) an electret layer disposed on said first surface of said light guidance substrate;

(2) a clear elastomer layer disposed on said electret layer;

(3) a rigid, clear cover plate, which cover plate has a surface, and which cover plate comprises on said surface of said cover plate a plurality of translucent interdigitated electrodes; and

(4) means for enabling the pixel for a varying fractional proportion of the burst time of said light source.

29. The optical display of claim 25 in which each of said pixels comprises a pair of interdigitated translucent electrodes disposed on said first surface of said light guidance substrate.

30. The optical display of claim 25 in which each of said pixels comprises:

(a) a translucent indium-tin oxide ground plane disposed on said first surface of said light guidance substrate;

(b) a translucent elastomer layer disposed on said ground plane; and

(c) a translucent indium-tin oxide electrode disposed on said elastomer layer.

31. The optical display of claim 25 in which each of said pixels comprises:

(a) a translucent indium-tin oxide ground plane disposed on said first surface of said light guidance substrate;

(b) a translucent elastomer layer disposed on said ground plane;

(c) a translucent indium-tin oxide electrode disposed on said elastomer layer; and

(d) a translucent dielectric disk which dielectric disk has a refractive index approximately that of said light guidance substrate.

32. A method for visually displaying data, which method comprises:

(a) channeling light in a light guidance substrate; and

(b) selectively defeating conditions for total internal reflection of said channeled light within said light guidance substrate by bringing a refractive-index-matched translucent element into the evanescent field emanating from said light guidance substrate due to the presence of channeled light therein, whereby said channeled light is allowed to escape to the environment of said light guidance substrate.

33. The method of claim 32 in which said step of channeling light in a light guidance substrate further comprises:

(a) providing a light source capable of emitting sequentially the three additive primaries; and

(b) reflecting substantially all of the light emitted by said light source into said light guidance substrate.

34. The method of claim 32 in which said step of channeling light in a light guidance substrate further comprises:

(a) providing a light source capable of emitting light of a given color; and

(b) reflecting substantially all of the light emitted by said light source into said light guidance substrate.

36. The method of claim 32 in which said step of selectively defeating conditions for total internal reflection within said light guidance substrate further comprises:

(a) interdigitating a pair of positive and negative conductors on the surface of a light guidance substrate; and

(b) applying current to said positive and negative conductors, whereby a rippling of said surface of said light guidance substrate allows light to escape from said light guidance substrate.

37. The method of claim 32 in which said light guidance substrate comprises a planar exterior surface and in which said step of selectively defeating conditions for total internal reflection further comprises:

(a) disposing an interdigitated pair of electrodes on said planar exterior surface of said light guidance substrate;

(b) forming an electret layer in parallel, spaced-apart relationship with said planar exterior surface of said light guidance substrate, said electret layer being formed within said light guidance substrate; and

(c) selectively charging said pair of electrodes with respective opposite charges.

38. The method of claim 32 in which said step of selectively defeating conditions for total internal reflection further comprises:

(a) disposing an interdigitated pair of electrodes on the exterior surface of a light guidance substrate;

(b) providing such spacing between the members of said pair of electrodes that a diffraction effect may be created upon charging of said electrodes; and

(c) selectively charging said pair of electrodes with respective opposite charges.

35. A method for visually displaying data, which method comprises:

(a) channeling light in a light guidance substrate, which step of channeling light in a light guidance substrate further comprises;

(1) providing a light source capable of emitting infrared light; and

(2) reflecting substantially all of the light emitted by said light source into said light guidance substrate; and

(b) selectively defeating conditions for total internal reflection of said channeled light within said light guidance substrate whereby said channeled light is allowed to escape to the environment of said light guidance substrate.

39. A method for visually displaying data, which method comprises:

(a) channeling light in a light guidance substrate; and

(b) selectively defeating conditions for total internal reflection of said channeled light within said light guidance substrate whereby said channeled light is allowed to escape to the environment of said light guidance substrate, which step further comprises;

(1) disposing a first electrode on the exterior surface of the light guidance substrate;

(2) encapsulating said electrode with a planar layer of room temperature vulcanizing silicone;

(3) disposing a second, translucent electrode on the exterior surface of said planar layer of room temperature vulcanizing silicone; and

(4) selectively charging said pair of electrodes with respective opposite charges.

40. A method for visually displaying data, which method comprises:

(a) channeling light in a light guidance substrate; and

(b) selectively defeating conditions for total internal reflection of said channeled light within said light guidance substrate whereby said channeled light is allowed to escape to the environment of said light guidance substrate, which step further comprises;

(1) disposing a first electrode on the exterior surface of the light guidance substrate;

(2) encapsulating said planar electrode with a planar layer of room temperature vulcanizing silicone;

(3) disposing a second, translucent electrode on the exterior surface of said planar layer of room temperature vulcanizing silicone;

(4) disposing a disk on said second electrode, which disk has refractive index approximately equal to that of said light guidance substrate; and

(5) selectively charging said first and second electrodes.

41. An optical shutter comprising:

(a) a light guidance substrate adapted to channel light, which light guidance substrate is comprised of a high-refractive-index substance;

(b) a deformable dielectric layer; and

(c) guidance-defeating means disposed on said deformable dielectric layer, which guidance-defeating means comprises a pair of parallel, translucent electrodes disposed on opposite surfaces of said deformable dielectric layer and means for selectively charging and discharging at least one of said electrodes, and which guidance-defeating means is adapted selectively to violate the light-guidance conditions for said light guidance substrate thus coupling any channeled light out of said light guidance substrate.

42. The optical shutter of claim 41 in which said guidance-defeating means further comprises a translucent disk formed of a high-refractive-index elastomer having a refractive index approximately equal to that of said light guidance substrate, which disk is disposed on one of said electrodes.

43. The optical shutter of claim 41 in which said guidance-defeating means is responsive to electrical control signals.

44. An optical shutter comprising:

(a) a light guidance substrate;

(b) a light-transmitting element having a refractive index approximately equal to that of said light guidance substrate, and which light-transmitting element is maintained in spaced-apart relationship from said light guidance substrate at a distance greater than the wavelength of any channeled light within said light guidance substrate; and

(c) means for selectively moving at least a portion of said light-transmitting element within a distance from said light guidance substrate less than one wavelength of any channeled light within said guidance substrate.

45. An optical display comprising:

(a) a light source;

(b) a light guidance substrate adapted to channel light emanating from said light source, and which light guidance substrate manifests an outward-extending evanescent field due to channeled light;

(c) a light-transmitting element having a refractive index approximately equal to that of said light guidance substrate, and which light-transmitting element is adapted selectively to move between two states;

(1) a first state in which said light-transmitting element is maintained in spaced-apart relationship from said light guidance substrate at a distance beyond the evanescent field emanating from said light guidance substrate; and

(2) a second state in which at least a portion of said light-transmitting element is maintained in spaced-apart relationship from said light guidance substrate at a distance within the evanescent field emanating from said light guidance substrate; and

(d) means for selectively moving said light-transmitting element between said first and second states, thus coupling any channeled light out of said light guidance substrate.

46. An optical display comprising:

(a) a light source;

(b) a light guidance substrate adapted to channel light from said light source;

(c) a transparent ground plane disposed on said light guidance substrate;

(d) a deformable dielectric layer disposed on said ground plane, which deformable dielectric layer has a thickness in the quiescent state greater than one wavelength of the channeled light;

(e) a transparent electrode disposed on said deformable dielectric layer;

(f) a transparent disk disposed on said transparent electrode, which transparent disk is fashioned of material having a refractive index approximately equal to the refractive index of said light guidance substrate; and

(g) means to selectively electrostatically charge said transparent electrode with respect to said ground plane, thus compressing said deformable dielectric layer and thereby pulling said transparent disk within the evanescent field emanating from said light guidance substrate.