Image display apparatus with modulators for modulating picture elements in an image

• US 5,978,142 A
• Filed: 09/03/1997
• Issued: 11/02/1999
• Est. Priority Date: 09/11/1996
• Status: Expired due to Term

• Current Assignee: Rockwell Collins, Inc. (Rtx Corporation)
• Original Assignee: Seos Display Ltd (Rtx Corporation)
• Inventors: Neale, Adam Richard, Blackham, Geoffrey Howard
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): MACK, RICKY LEVERN
• Application Number:
  US08/922,868
• Time in Patent Office: 790 Days
• Field of Search: 359/618, 359/267, 359/277, 348/758, 353/122
• US Class Current: 359/618
• CPC Class Codes: G02F 1/13471 in which all the liquid crystal cells or layers remain transparent, e.g. FLC, ECB, DAP, HAN, TN, STN, SBE-LC cells G02F1/13475 takes precedence
• CPC Class Codes: G03B 21/005 Projectors using an electronic spatial light modulator but not peculiar thereto
• CPC Class Codes: G03B 21/26 Projecting separately subsidiary matter simultaneously with main image
• CPC Class Codes: H04N 5/57 Control of contrast or brightness
• CPC Class Codes: H04N 5/7441 the modulator being an array of liquid crystal cells
• CPC Class Codes: H04N 9/12 Picture reproducers H04N9/11 takes precedence
• CPC Class Codes: H04N 9/3126 for spatial light modulators in series

Abstract

Image display apparatus comprising projector means, a first modulator and a second modulator, the first and the second modulators being such as to modulate picture elements in an image whereby finite minimum image brightness above true black is reduced, and whereby the contrast range of the projected image is extended.

Claims

1. Image display apparatus comprising projector means, a light source, a first modulator, a second modulator, and relay means, the first and the second modulators both being such as to modulate light received from the light source, the first modulator modulating the light to produce an image, the relay means optically relaying the image to the second modulator, the second modulator being such as to further modulate the image to perform optical image enhancement whereby finite minimum image brightness above true black is reduced, whereby contrast range of the projected image is extended, and whereby the optical image enhancement achieved is determined by a driving signal to the second modulator.

2. Image display apparatus according to claim 1 in which the second modulator is driven with a said driving signal which is an amplified version of a drive signal to the first modulator.

3. Image display apparatus according to claim 1 in which functional signals which are different from each other are used to drive the first and the second modulators.

4. Image display apparatus according to claim 1 in which functions of drive signals for the first and the second modulators are combined for some of the picture elements.

5. Image display apparatus according to claim 1 in which the second modulator is one which is matrix addressed.

6. Image display apparatus according to claim 1 in which the second modulator is placed at a focal plane.

7. Image display apparatus according to claim 1 in which the light source illuminates the first and the second modulators with collimated light.

8. Image display apparatus according to claim 1 in which the second modulator comprises a liquid crystal display panel and a polarizing sheet analyzer.

9. Image display apparatus according to claim 1 in which the relay means is a relay lens or direct optical coupling.