Low-cost, substantially cross-talk free high spatial resolution 2-D bistable light modulator

• US 4,822,993 A
• Filed: 02/25/1988
• Issued: 04/18/1989
• Est. Priority Date: 02/17/1987
• Status: Expired due to Term

• Current Assignee: Optron Systems Incorporated
• Original Assignee: Optron Systems Incorporated
• Inventors: Dillon, Robert F., Warde, Cardinal
• Primary Examiner(s): Nelms, David C.
• Assistant Examiner(s): Allen, Stephone B.
• Application Number:
  US07/160,184
• Time in Patent Office: 418 Days
• Field of Search: 250/213 VT, 250/213 R, 313/103 CM, 313/103 R, 313/105 CM, 313/523, 313/334
• US Class Current: 250/214.0LA
• CPC Class Codes: H01J 31/24 with screen acting as light valve by shutter operation, e.g. eidophor projection arrangements for image reproduction, e.g. using eidophor H04N5/74

Abstract

In one voltage-driven embodiment, a high spatial resolution two-dimensional array of bistable completely cross-talk free light modulation elements is constituted as a lamination of an input two-dimensional photoconductor thin film layer and an output two-dimensional electroluminescent phosphor thin film layer disposed in etched wells individually defined in corresponding cores of the optical fibers of a fiber optic face plate. In another voltage-driven embodiment, a very low cost high spatial resolution 2-D array of bistable substantially cross-talk free light modulation elements is constituted as a lamination of a photoconductor thin film layer, a selectively dimensioned and apertured opaque masking thin film layer, and an electroluminescent phosphor thin film layer. In an electron-driven embodiment, a high spatial resolution two-dimensional array of substantially cross-talk free bistable light modulating elements is constituted as an assembly of a two-dimensional input window having a deposited photocathode thin film layer, a two-dimensional output window having a deposited cathodoluminescent phosphor, and a two-dimensional glass capillary array.

Claims

1. A low cost substantially cross-talk free voltage driven high spatial resolution two-dimensional light modulator responsive to two-dimensional input signals of variable intensity, comprising:

a first planar two-dimensional transparent substrate;

a first planar two-dimensional transparent conductor disposed on one surface of said transparent substrate;

a planar two-dimensional electroluminescent phosphor thin film layer having a predetermined thickness disposed on the exposed surface of said first transparent conductor, said predetermined thickness being selected to provide a predetermined capacitance and a predetermined resistance for said electroluminescent phosphor film;

an opaque mask having a plurality of apertures disposed on said electroluminescent phosphor thin film layer, said plurality of apertures having predetermined dimensions and spacing to provide an array of pixels having an intended degree of cross-talk isolation for a given spatial resolution;

an input planar two-dimensional photoconductor thin film layer having a predetermined thickness disposed on the exposed face of said opaque mask, said predetermined thickness being selected to provide a predetermined capacitance and a predetermined dark resistance for said photoconductor thin film layer and to tune said light modulator to a predetermined input signal intensity threshold level;

a second planar transparent two-dimensional conductor disposed on said photoconductor thin film layer; and

means coupled to said first and second conductors for biasing said first and second conductors with a predetermined voltage; and

wherein

said predetermined capacitance of said electroluminescen tphosphor thin film layer is substantially smaller than a predetermined capacitance of said photoconductor thin layer film and said predetermined dark resistance of said photoconductor thin film layer is greater than said predetermined resistance of said electroluminescent phosphor thin film layer wherein

said light modulator is responsive to the two-dimensional input signals of variable intensity less than said predetermined input signal intensity threshold level to cause said electroluminescent phosphor thin film layer to produce output intensities proportional to the intensity of the two-dimensional input signals; and

wherein

said light modulator is responsive to the two-dimensional input signals of variable intensity of at least said predetermined input signal intensity threshold level to cause said electroluminescent phosphor thin film layer to produce a constant output intensity which is thereafter independent of the intensity of the two-dimensional input signals; and

further wherein

said constant output intensity of said electroluminescent thin layer film is greater than said predetermined input signal intensity threshold level of said photoconductor thin film layer to provide optical gain for said light modulator.

2. The low cost modulator of claim 1, wherein said opaque mask is formed from an ink that is opaque to light.

3. The low cost modulator of claim 1, further including means for hermetically sealing said first and second transparent conductors, said electroluminescent phosphor, said apertured opaque mask and said photoconductor to said first transparent substrate.

4. The low cost modulator of claim 3, further including a transparent, non-conducting sealer coating disposed intermediate said apertured opaque mask and said photoconductor to prevent chemical deterioration.

5. The low cost modulator of claim 4, further including a high dielectric strength coating disposed intermediate said photoconductor and said second transparent conductor to prevent electrical arcing.

6. The low cost modulator of claim 5 wherein said means for hermetically sealing said first and second transparent conductors, said photoconductor, said high dielectric strength coating, said transparent, non-conducting sealer, said apertured opaque mask and said electroluminescent phosphor further includes a second planar two-dimensional transparent substrate disposed on the exposed surface of said second transparent conductor to act as a two-dimensional input window.

7. A low cost substantially cross-talk free voltage driven high spatial resolution two-dimensional light modulator, comprising:

a planar two-dimensional transparent substrate;

a first planar two-dimensional transparent conductor disposed on one surface of said transparent substrate;

a planar two-dimensional electroluminescent phosphor having a predetermined thickness disposed on the exposed surface of said first transparent conductor;

an opaque mask having a plurality of apertures disposed on said electroluminescent phosphor, said plurality of apertures being spaced apart by opaque regions of predetermined dimensions selected to provide said light modulator with an intended 2-D spatial resolution and an intended degree of cross-talk isolation; and

wherein

said predetermined dimensions of said opaque portions of said opaque mask are selected to be larger than said predetermined thickness of said electroluminesent phosphor to provide said intended degree of cross-talk isolation;

an input planar two-dimensional photoconductor disposed on the exposed face of said opaque mask; and

a second planar transparent conductor disposed on said photoconductor.