Color helmet mountable display

• US 5,612,708 A
• Filed: 04/22/1996
• Issued: 03/18/1997
• Est. Priority Date: 06/17/1994
• Status: Expired due to Term

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Inventors: Ansley, David A., Beamon, III, William S.
• Primary Examiner(s): Tung, Kee M.
• Assistant Examiner(s): CHOW, DOON Y
• Application Number:
  US08/636,025
• Time in Patent Office: 330 Days
• Field of Search: 345/7, 345/8, 345/9, 359/13, 359/14, 359/619, 359/630, 359/631, 359/632, 351/158, 340/980, 348/61, 348/121, 348/115
• US Class Current: 345/8
• CPC Class Codes: G02B 2027/0112 comprising device for genereting colour display
• CPC Class Codes: G02B 2027/0132 comprising binocular systems
• CPC Class Codes: G02B 2027/014 comprising information/image processing systems
• CPC Class Codes: G02B 2027/0154 with movable elements
• CPC Class Codes: G02B 27/017 Head mounted
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 7/12 Adjusting pupillary distance of binocular pairs
• CPC Class Codes: H04N 9/3132 using one-dimensional electronic spatial light modulators
• CPC Class Codes: H04N 9/3138 using arrays of modulated light sources electroluminescent display devices G09G3/30

Abstract

A lighter weight helmet mountable display (HMD) that is easily adjustable to accommodate variable inter-pupillary distances includes substantially parallel left and right optical channels, and projects left and right images onto the helmet'"'"'s visor. Each channel includes light sources that form a complete scan line of the image, and project luminance patterns for successive scan lines through a lens which reduces the light'"'"'s divergence. A deflector is moved to deflect successive luminance patterns back through the lens so that the lens focuses the patterns onto successive scan lines on a back projection screen. The screen emits luminance patterns in response to the incident luminance patterns for each successive scan line to project the image onto the visor.

Claims

1. A helmet mountable display system for displaying left and right pixelated images onto a visor for viewing by a wearer of the helmet, said display system comprising:

left and right optical channels having respective central optical axes that are substantially parallel to each other, each channel comprising;

an array of light sources forming a complete scan line of said image in one-to-one correspondence with the image pixels, said light sources projecting first divergent luminance patterns for successive scan lines;

a lens for reducing the divergence of said first luminance patterns;

a back projection screen positioned to project said images onto the visor;

a scanning deflector; and

a deflector actuator controlling said scanning deflector to deflect successive first luminance patterns transmitted through the lens back through said lens so that the lens focuses the patterns onto successive scan lines on the screen'"'"'s back side, said screen emitting a second luminance pattern for each successive scan line to project the pixelated image onto the visor,

said deflector actuators in said left and right optical channels comprising a single common drive motor for controlling both deflectors.

2. The helmet mountable display system of claim 1, further comprising an adjustment mechanism for adjusting the separation distance between said parallel channels without moving said deflectors and deflector actuators so that the distance can be set substantially equal to a wearer'"'"'s interpupillary distance.

3. The helmet mountable display system of claim 1, wherein said lens and said deflector capture an angle of the diverging light, the size of the deflector being selected to capture the minimum angle of light needed to resolve the individual sources at the screen.

4. The helmet mountable display system of claim 3, wherein the light projected at said minimum angle along the focal length of said lens provides a first illumination area, and said back projection screen projects said second luminance patterns at another angle to provide a second illumination area larger than the first.

5. The helmet mountable display system of claim 1, wherein said lens collimates the divergent luminance pattern from said light sources.

6. The helmet mountable display system of claim 5, wherein said lens comprises a plurality of lens elements for collimating said divergent luminance patterns, and for focusing said deflected luminance patterns onto said screen.

7. The helmet mountable display system of claim 1, wherein said light sources are light emitting diodes (LEDs).

8. The helmet mountable display system of claim 1, further comprising:

a circuit for reading out successive scan lines from said images, and modulating said light sources to project the first luminance patterns.

9. The helmet mountable display system of claim 8, wherein said circuit modulates said light sources at a scanning rate, and said deflector actuator moves said deflector at a rate synchronized to said scanning rate.

10. The helmet mountable display system of claim 9, wherein said deflector is a multi-faceted mirror, and said deflector actuator rotates said mirror such that the facets of said mirror deflect respective successive images onto said screen.

11. The helmet mountable display system of claim 8, wherein said circuit reads out said image in a raster scan format, and modulates said light sources sequentially.

12. The helmet mountable display system of claim 8, wherein said circuit reads out said image a complete scan line at a time, and modulates the light sources simultaneously.

13. The helmet mountable display system of claim 8, wherein said array comprises multiple linear adjacent arrays with mutually staggered light sources, said circuit temporally staggering the modulation of the light sources among said arrays such that luminance patterns are deflected from each array onto the same scan line on the screen.

14. The helmet mountable display system of claim 8, wherein said images are color images with red, green and blue (RGB) components, and said light sources include red, green, and blue light source arrays each in one-to-one correspondence with the scan line, said circuit delaying the modulation of the three arrays such that the luminance patterns for the three arrays are coincident on the same projected scan line, and said back projection screen projecting color luminance patterns onto the visor.

15. The helmet mountable display system of claim 1, wherein said array of light sources is linear.

16. A helmet mountable display (HMD), comprising:

parallel left and right optical channels for projecting left and right images scan lines;

left and right scanning deflectors;

a common drive motor for controlling said scanning deflectors to deflect successive image scan lines back through the optical channels to project an image onto a visor; and

an adjustment mechanism that adjust the spacing between the channels without moving the left and right scanning deflectors to accommodate varying inter-pupillary distances while maintaining the channels parallel orientation to prevent distortion.

17. The HMD of claim 16, wherein said image has a plurality of pixels in each scan line, each optical channel including light sources in one-to-one correspondence with the pixels in each scan line for projecting the image scan lines onto said scanning deflector.

18. The HMD of claim 17, wherein the HMD includes only one pair of scanning deflectors, and said pair of scanning deflectors share only one common drive motor.