Method and apparatus for increasing effective contrast ratio and brightness yields for digital light valve image projectors

• US 20050052621A1
• Filed: 08/06/2004
• Published: 03/10/2005
• Est. Priority Date: 08/08/2003
• Status: Active Grant

• Current Assignee: RPX Corporation
• Original Assignee: Eclipse Video Technology, LLC
• Inventors: Coley, Christopher, Allen, Eddie, Strade, Thomas
• Granted Patent: US 7,220,006 B2
• Time in Patent Office: Days
• US Class Current: 353/85
• CPC Class Codes: G03B 21/2053 Intensity control of illuminating light controlled by video signal processing H04N5/74 or H04N9/31
• CPC Class Codes: H04N 5/7416 involving the use of a spatial light modulator, e.g. a light valve, controlled by a video signal
• CPC Class Codes: H04N 9/3155 for controlling the light source light source control per se H05B35/00 – H05B47/00; control of an illumination source for displays in general G09G3/3406
• CPC Class Codes: H04N 9/3182 Colour adjustment, e.g. white balance, shading or gamut white balance per se H04N9/73; control of amplitude of colour signals H04N9/68; colour control circuits for displays in general G09G5/02, G09G3/2003, G09G3/3607
• CPC Class Codes: H04N 9/3197 using light modulating optical valves

Abstract

The present invention is a method and apparatus for increasing the effective contrast ratio and brightness yields for digital light valve image projectors using a variable luminance control mechanism (VLCM), associated with the projector optics, for modifying the light output and provide a correction thereto; and an adaptive luminance control module (ALCM) for receiving signals from said video input board, said adaptive luminance control module producing a signal on a VLCM bus connecting the variable luminance control mechanism and the adaptive luminance control module, said signal causing the variable luminance control mechanism to change the luminance of the light output and provide a corrected video signal for the projector.

Claims

13-1. The apparatus of claim 13, wherein the electrochromic device is a display including a nanocrystalline film.

14. A method for improving the operation of a digital image projector, comprising the steps of:

receiving video signals from a video input board in the projector; and

producing a first signal, using an adaptive luminance control module, to provide control information for a variable luminance control mechanism located within the optical path of the projector and a second signal which is a modified video signal, whereby the variable luminance control mechanism operates to produce a modified light output from said digital image projector.

15. The method of claim 14, further comprising the steps of:

receiving video signals and buffering the signals;

deriving a characteristic of the buffered video signals and producing a luminance content signal; and

receiving the luminance content signal and looking-up a modified video signal in response to the buffered video signal and the luminance content signal.

16. The method of claim 15, further comprising the step of receiving the luminance content signal and producing, in response thereto, a control signal including a current, voltage and buffering drive signal in proportion to the luminance content signal.

17. The method of claim 14, wherein the variable luminance control mechanism includes an electronically controllable iris and wherein the method further comprises the step of altering the position of at least one component in the iris in response to the control signal.

18. The method of claim 14, wherein the variable luminance control mechanism includes an electrochromic device and wherein the method further comprises the step of altering the transmittance of at least a portion of the electrochromic device in response to the control signal.