Dmd-based image display systems

• US 20030142274A1
• Filed: 12/09/2002
• Published: 07/31/2003
• Est. Priority Date: 03/15/2000
• Status: Active Grant

• Current Assignee: IMAX Corporation
• Original Assignee: IMAX Corporation
• Inventors: Read, Steven, Gibbon, Michael A., Adkins, Sean, Zhou, Samuel Ziheng
• Granted Patent: US 7,224,335 B2
• Time in Patent Office: Days
• US Class Current: 353/31
• 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: G09G 1/06 using single beam tubes G09G1/26, G09G1/28 take precedence, e.g. three-dimensional or perspective representation, rotation or translation of display pattern, hidden lines, shadows G09G1/28 takes precedence; stereoscopic TV-systems, details thereof H04N13/00; oscilloscopes for three-dimensional representation G01R13/206; vectorscopes G01R13/208
• CPC Class Codes: G09G 2300/02 Composition of display devices
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2320/0261 in the context of movement of objects on the screen or movement of the observer relative to the screen
• CPC Class Codes: G09G 2340/0428 Gradation resolution change
• CPC Class Codes: G09G 3/001 using specific devices not provided for in groups G09G3/02 - G09G3/36, e.g. using an intermediate record carrier such as a film slide; Projection systems; Display of non-alphanumerical information, solely or in combination with alphanumerical information, e.g. digital display on projected diapositive as background slide projectors per se G03B23/00 = 42 HP
• CPC Class Codes: G09G 3/2014 by modulation of the duration of a single pulse during which the logic level remains constant
• CPC Class Codes: G09G 3/2018 by time modulation using two or more time intervals
• 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 5/7416 involving the use of a spatial light modulator, e.g. a light valve, controlled by a video signal
• CPC Class Codes: H04N 5/7458 the modulator being an array of deformable mirrors, e.g. digital micromirror device [DMD]
• CPC Class Codes: H04N 9/3105 for displaying all colours simultaneously, e.g. by using two or more electronic spatial light modulators simultaneous projection in colour photography G03B33/10; beam splitting or combining systems per se G02B27/10
• CPC Class Codes: H04N 9/3123 using pulse width modulation
• CPC Class Codes: H04N 9/3126 for spatial light modulators in series

Abstract

A projection system having a controller and a plurality of reflective SLMs operatively coupled to the controller to receive image data from the controller. The reflective SLMs are aligned in series to receive light from a light source and to reflect imaging light correlated to the image data.

Claims

1. A projection system comprising:

(a) a first SLM having a first array of separately addressable pixels, the first SLM adapted to receive light from a light source and to modulate light into a subsequent SLM;

(b) a second SLM having a second array of separately addressable pixels, the second SLM positioned in series with the first SLM to receive modulated light from the first SLM and to direct that light for producing an output;

(c) a controller coupled to the first SLM for delivering first image data to the first SLM, and coupled to the second SLM for delivering second image data to the second SLM, said first and second image data being correlated to provide a viewable image at said output.

2. The projection system as claimed in claim 1, wherein the first SLM is a digtal micro mirror device and wherein the first array is an array of addressable micro mirrors.

3. The projection system as claimed in claim 1 wherein the second SLM is a digital micro mirror device and wherein the second array is an array of addressable micro mirrors.

4. The projection system as claimed in claim 3 wherein each micro mirror in the second array corresponds to a pixel in the first array.

5. The projection system as claimed in claim 1 wherein the first image data comprises first intensity data for each pixel in the first array.

6. The projection system as claimed in claim 1, wherein the second image data comprises second intensity data for each pixel in the second array.

7. The projection system as claimed in claim 5, wherein the first intensity data comprises first pulse width modulation data.

8. The projection system as claimed in claim 6, wherein the second intensity data comprises second pulse width modulation data.

9. The projection system as claimed in claim 1, further comprising a color wheel operatively coupled to the controller for providing color to the viewable image.

10. The projection system as claimed in claim 1, further comprising a relay for aligning the imaging light onto the second SLM.

11. The projection system as claimed in claim 1, further comprising a projection lens.

12. The projection system as claimed in claims 5 and 6, wherein the first intensity data and the second intensity data are determined in accordance with a bitmap code.

13. The projection system as claimed in claim 12, wherein the bitmap code correlates first intensity data with second intensity data.

14. The projection system as claimed in claim 12, wherein the bitmap code is formatted by providing approximately equally spaced brightness levels for the first SLM and selecting code words based on error minimization resulting in a plurality of new code words with a performance equivalent to a bit-depth of six bits.

15. The projection system as claimed in claim 13, wherein the product of correlated first intensity data and second intensity data is substantially linear.

16. The projection system as claimed in claim 13, wherein the product of correlated first intensity data and second intensity data is substantially curvilinear.

17. The projection system as claimed in claim 13, wherein the product of correlated first intensity data and second intensity data is substantially non-uniform.

18. The projection system as claimed in claim 13, wherein first intensity data and the second intensity data are determined such that adjacent products of correlated first intensity data and second intensity differ in quantity approximately in accordance with human ability to detect variations in light intensity levels.

19. A projection system comprising:

(a) a controller;

(b) a plurality of SLMs operatively coupled to the controller to receive image data from the controller; and

(c) wherein the SLMs are aligned in series to receive light from a light source and to direct imaging light correlated to the image data.

20. The projection system as claimed in claim 19 wherein each of the plurality of SLMs in series comprises a set of at least three color specific SLMs.

21. A method of increasing the contrast ratio of a projection system that includes multiple SLMs, a light source, a controller, and a projection lens, wherein the SLMs have arrays with separately addressable pixels, the method comprising:

receiving image data having data words representing pixel values; and

allocating image data between multiple SLMs in series to increase the dynamic range.

22. The method of claim 21, wherein the image data is allocated using a bitmap code.

23. The projection system as claimed in claim 22, wherein the bitmap code is formatted by providing approximately equally spaced brightness levels for the first SLM and selecting code words based on error minimization resulting in a plurality of new code words with a performance equivalent to a bit-depth of six bits.