Fault tolerant projective display having redundant light modulators

• US 5,815,303 A
• Filed: 06/26/1997
• Issued: 09/29/1998
• Est. Priority Date: 06/26/1997
• Status: Expired due to Term

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Berlin, Andrew A.
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): Duong, Tai V.
• Application Number:
  US08/883,418
• Time in Patent Office: 460 Days
• Field of Search: 359/213, 359/214, 359/223, 359/224, 359/225, 359/226, 359/291, 359/292, 359/295, 359/298, 345/84, 345/85, 348/755, 348/756, 348/757, 348/764, 348/770, 348/771, 349/5, 349/8, 349/73, 349/74, 349/143, 349/158
• US Class Current: 359/196.1
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 26/085 the reflecting means being moved or deformed by electromagnetic means
• CPC Class Codes: G02B 26/0858 the reflecting means being moved or deformed by piezoelectric means
• CPC Class Codes: G02B 26/101 with both horizontal and vertical deflecting means, e.g. raster or XY scanners colour television using laser beams scanning a display screen H04N9/3129
• CPC Class Codes: G09G 2330/08 Fault-tolerant or redundant circuits, or circuits in which repair of defects is prepared
• CPC Class Codes: G09G 3/002 to project the image of a two-dimensional display, such as an array of light emitting or modulating elements or a CRT
• CPC Class Codes: G09G 3/007 Use of pixel shift techniques, e.g. by mechanical shift of the physical pixels or by optical shift of the perceived pixels
• CPC Class Codes: G09G 3/346 based on modulation of the reflection angle, e.g. micromirrors micromirrors devices per se G02B26/0833
• CPC Class Codes: H04N 5/21 Circuitry for suppressing or minimising disturbance, e.g. moiré or halo
• CPC Class Codes: H04N 5/7441 the modulator being an array of liquid crystal cells

Abstract

A projective display system includes a light source, a display surface, and a two dimensional light modulator array in an optical path between the light source and the display surface. The two dimensional light modulator array has a plurality of light modulators arranged in rows to modulate light from the light source, with at least one row being susceptible to failure. To compensate for any failed rows, a redundant light modulator array is provided, with modulated light output of the redundant light modulator array being directed by an optical element positioned to selectively substitute for at least one failed row of light modulators.

Claims

1. A display system comprising

a light source,

a display surface,

a two dimensional light modulator array in an optical path between the light source and the display surface, the two dimensional light modulator array having a plurality of light modulators arranged in rows to modulate light from the light source, with at least one row being susceptible to failure,

a redundant light modulator array having a second plurality of light modulators arranged in rows to modulate light from the light source, and

an optical element positioned to selectively direct light incident on the redundant light modulator array toward the display surface to substitute for at least one failed row of light modulators in the two dimensional light modulator array.

2. The display system of claim 1, wherein the plurality of light modulators reflect light.

3. The display system of claim 1, wherein the optical element selectively directs light incident on at least two rows of the redundant light modulator array to substitute for at least two failed rows of light modulators in the two dimensional light modulator array.

4. The display system of claim 1, further comprising an actuator to move the optical element between predetermined positions.

5. The display system of claim 4, wherein the two dimensional light modulator array is movable with respect to the optical element, and wherein the optical element is movable to track movement of the two dimensional light modulator array.

6. The display system of claim 5, wherein the actuator moves the optical element at a frequency greater than about 10 kHz.

7. The display system of claim 1, wherein the redundant light modulator has substantially as many light modulators as the two dimensional light modulator array.

8. A display system comprising

a substrate,

a two dimensional light modulator array movably mounted with respect to the substrate, the two dimensional light modulator having a plurality of light modulators arranged to form at least one row to modulate light,

a redundant light modulator array movably mounted with respect to the substrate, the redundant light modulator having a plurality of light modulators arranged to form at least one redundant row to modulate light, with the redundant row positioned adjacent to the at least one row of the two dimensional light modulator array, and

a movable element for moving the two dimensional light modulator array and the redundant array relative to the substrate, with the movable element moving the redundant row to transiently occupy the position of at least one row of the two dimensional light modulator array.