Electro-optical display apparatus

• US 6,219,011 B1
• Filed: 09/17/1997
• Issued: 04/17/2001
• Est. Priority Date: 09/17/1996
• Status: Expired due to Fees

• Current Assignee: Comview Graphics Limited
• Original Assignee: Comview Graphics Limited
• Inventors: Rosenthal, Amir, Elmaliah, Nissim, Aloni, Meir, Livni, Avinoam
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): Tran, Henry N.
• Application Number:
  US08/931,942
• Time in Patent Office: 1,308 Days
• Field of Search: 345/1, 345/30-32, 345/36-42, 345/63, 345/77, 345/81, 345/87, 345/90, 345/142-147, 345/207, 340/815.42, 348/383, 348/745, 348/750, 348/751
• US Class Current: 345/1.3
• CPC Class Codes: G06F 3/147 using display panels
• CPC Class Codes: G09G 2300/026 Video wall, i.e. juxtaposition of a plurality of screens to create a display screen of bigger dimensions
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0693 Calibration of display systems
• CPC Class Codes: H04N 17/04 for receivers
• CPC Class Codes: H04N 9/28 Arrangements for convergence or focusing
• CPC Class Codes: H04N 9/3147 Multi-projection systems displays in general H04N9/12; video walls G06F3/1446, G09G2300/026
• CPC Class Codes: H04N 9/3185 Geometric adjustment, e.g. keystone or convergence optical or mechanical adjustment of convergence H04N9/317; using scanning means H04N3/22; optical or mechanical adjustments of projectors not peculiar to the presence of an electronic spatial light modulator G03B21/14
• CPC Class Codes: H04N 9/3194 including sensor feedback

Abstract

Electro-optical display apparatus includes a plurality of modular units each having a projector for receiving electrical signals, converting them to optical images, and projecting the optical images via an optical projection system onto a screen. The modular units are arranged in a side-by-side array such as to produce a combined display on the screen. A calibration system detects distortions in the combined display caused by the projection system of each modular unit and modifies the electrical signals applied to the projector of each modular unit to correct the combined display with respect to the detected distortions.

Claims

1. Electro-optical display apparatus, comprising:

a plurality of modular units each including a projector for receiving electrical signals, converting them to optical images, and projecting said optical images via an optical projection system onto a screen;

said plurality of modular units being arranged in a side-by-side array such as to produce a combined display on said screen;

said apparatus further comprising a calibration system including an image sensor for sensing an optical image on said screen, and imaging means spaced from the screen and producing an image of the screen on said image sensor, for detecting geometrical distortions in said combined display caused by said projection system of each modular unit and for modifying the electrical signals applied to said projector of each modular unit to correct said combined display with respect to said detected geometrical distortions;

said image sensor and imaging means being located on the same side of the screen as the projectors for the plurality of modular units;

said calibration system further including a two-dimensional array of reference points of known locations on the face of said screen, and means for generating a projector-path correction table for each modular unit for correcting discrepancies between the known locations of said two-dimensional array of reference points on said screen and the corresponding locations of the two-dimensional array of reference points as projected on said screen.

2. The apparatus according to claim 1,

wherein said screen is constituted of a plurality of modular unit screens, one provided on each of said modular units;

and wherein said imaging means includes an imaging lens for each modular unit for imaging its respective modular unit screen on said image sensor.

3. The apparatus according to claim 1, wherein said imaging means is an imaging lens, and said screen is of a size and configuration to overlie all said modular units.

4. The apparatus according to claim 1, wherein said two-dimensional array of reference points are defined by the intersection points of a plurality of horizontal reference lines and a plurality of vertical reference lines on said screen.

5. The apparatus according to claim 4, wherein said horizontal and vertical reference lines are produced by luminescent material carried on a face of said screen, and a light source for exciting said luminescent material to cause it to emit light.

6. The apparatus according to claim 5, wherein said screen is a light-transmissive screen and said reference lines of luminescent material are on the rear face of said screen, the front face of said screen serving as a writing surface.

7. The apparatus according to claim 1, wherein said two-dimensional array of reference points are the ends of optical fibers on said screen.

8. The apparatus according to claim 1, wherein said calibration system also generates an image path correction table for each modular unit for correcting discrepancies between the known locations of said two-dimensional array of reference points on said screen and the corresponding locations of the two-dimensional array of reference points as imaged on said screen.

9. The apparatus according to claim 1, wherein said calibration system also utilizes said two-dimensional array of reference points on said screen to combine the displays such as to eliminate overlaps and gaps in said combined display.

10. The apparatus according to claim 1, wherein said screen further includes a plurality of optical fibers having one of their ends at a plurality of spaced locations on the inner face of said screen for sensing the light intensity at said locations;

and wherein said apparatus further includes light detectors connected to the opposite ends of said optical fibers producing electrical outputs corresponding to said sensed light intensity, and a control circuit for controlling the optical projectors of said modular units to make uniform their light intensities.

11. The apparatus according to claim 1, wherein:

each of said projectors includes a drive having a plurality of degrees of movement;

and said calibration system also corrects at least some of the detected distortions by controlling the drives of said projectors.

12. The apparatus according to claim 1, wherein said calibration system also detects and corrects color convergence distortions by:

imaging a plurality of neighboring projected regions to produce an optical image of such neighboring regions on an image sensor;

analyzing said optical image to estimate the color convergence distortions in the color pixels of said image;

and digitally relocating each color pixel in said combined display a sub-pixel value to correct for said color convergence distortions.

13. The apparatus according to claim 1, wherein;

each projector includes a Fresnel lens which collimates the light from the respective projector;

said screen being a common screen having a light-diffusing surface overlying all said Fresnel lenses;

and wherein said apparatus further includes a blocking element underlying junctures between adjacent Fresnel lenses in order to reduce overlapping of the light from the projectors and thereby to produce a seamless combined display.

14. A method of producing an electro-optical display, comprising:

providing a plurality of modular units each including a projector for receiving electrical signals, converting them to optical images, and projecting said optical images via an optical projection system on a screen;

arranging said plurality of modular units in a side-by-side array such as to combine their respective displays to produce a combined display;

imaging said screen via imaging means spaced from the screen and producing an image of the screen on an image sensor on the same side of the screen as the projectors of the modular units for detecting geometrical distortions in said combined display;

and modifying the electrical signals applied to said projector of each modular unit to correct said combined display with respect to said detected geometrical distortions by producing a two-dimensional array of reference points at known locations on the face of said screen, and generating a projector-path correction table for each modular unit for correcting discrepancies between the known locations of said two-dimensional array of reference points on said screen and the corresponding locations of the two-dimensional array of reference points as projected on said screen.

15. The method according to claim 14, wherein said two-dimensional array of reference points are produced by the intersection points of a plurality of horizontal reference lines and a plurality of vertical reference lines applied to said screen.

16. The method according to claim 15, wherein said horizontal and vertical reference lines are produced by depositing luminescent material on the face of said screen, and exciting said luminescent material by a light source to cause it to emit light.

17. The method according to claim 16, wherein said reference lines of luminescent material are applied to the rear face of said screen, the front face of said screen serving as a writing surface.

18. The method according to claim 14, wherein said two-dimensional array of reference points are produced by the ends of optical fibers carried by said screen.

19. The method according to claim 14, wherein an image path correction table is also generated for each modular unit for correcting discrepancies between the known locations of said two-dimensional array of reference points on said screen and the corresponding locations of the two-dimensional array of reference points as imaged on said screen.

20. The method according to claim 14, wherein said two-dimensional array of reference points on said screen are utilized to combine the displays of the modular units such as to eliminate overlaps and gaps in said combined display.

21. The method according to claim 14, wherein the light intensity is sensed at each of a plurality of spaced locations on the inner face of said screen;

and the optical projectors of said modular units are controlled to make uniform their light intensities.

22. The method according to claim 14, wherein:

each of said projectors includes a drive having a plurality of degrees of movement;

and the drives of said projectors are controlled to correct at least some of the detected distortions.

23. The method according to claim 14, wherein color distortions are also corrected by detecting the intensity of each color component in the combined display;

and modifying the electrical signals applied to said projector of each modular unit to correct said combined display with respect to said color distortions.

24. The method according to claim 14, wherein color convergence distortions are corrected by:

imaging a plurality of neighboring projected regions to produce an optical image of such neighboring regions on an image sensor;

analyzing said optical image to estimate the color convergence distortions in the color pixels of said image;

and digitally relocating each color pixel in said combined display a sub-pixel value to correct for said color convergence distortions.

25. The method according to claim 14, wherein;

each projector includes a Fresnel lens which collimates the light from the respective projector;

and a common screen having a light-defusing surface overlying all said Fresnel lenses;

and a blocking element is provided to underlie the juncture between adjacent Fresnel lenses in order to reduce overlapping of the light from the projectors and thereby to produce a seamless combined display.