Field sequential color head mounted display with suppressed color break-up

• US 5,684,498 A
• Filed: 06/26/1995
• Issued: 11/04/1997
• Est. Priority Date: 06/26/1995
• Status: Expired due to Fees

• Current Assignee: CAE Incorporated
• Original Assignee: CAE USA Incorporated (CAE Incorporated)
• Inventors: Fernie, Andrew, Welch, Brian L.
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): CHANG, KENT WU
• Application Number:
  US08/494,822
• Time in Patent Office: 862 Days
• Field of Search: 345/7, 345/8, 345/9, 345/12, 345/13, 345/32, 345/115, 345/150
• US Class Current: 345/8
• CPC Class Codes: G02B 2027/0187 slaved to motion of at least a part of the body of the user, e.g. head, eye
• CPC Class Codes: G02B 2027/0198 System for aligning or maintaining alignment of an image in a predetermined direction
• CPC Class Codes: G02B 27/017 Head mounted
• CPC Class Codes: G09B 9/307 by helmet-mounted projector or display G09B9/36 takes precedence; optical parts of head-up displays G02B27/01
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 3/2018 by time modulation using two or more time intervals
• CPC Class Codes: G09G 5/02 characterised by the way in which colour is displayed details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607

Abstract

For displaying moving images on a field sequential color display device from a simultaneous color image source, without color break-up appearing in the observed image, an image shift device is provided for shifting each color component image within each cycle of color component images representing each frame of the simultaneous color video image source. The display device is for use with head mounted displays in which an LCD or a CRT screen is used to display field sequential color images without color break-up during head motion.

Claims

1. A field sequential color display device for use in displaying an image of an environment comprising:

a field sequential image generator for sequentially generating a cycle of color component images of a color image on a head mounted display screen from a simultaneous color video image source;

color filter means for making said color component images of said cycle appear to have a different color, such that a mixing of said color component images as seen with said color filter means provides an observer with said color image;

means for determining an angular velocity of a head of said observer and for generating a head velocity signal; and

image shift means for shifting on said screen said color component images of said cycle with respect to one another as a function of said velocity signal, whereby color break-up in said field sequential color display is suppressed.

2. The display device as claimed in claim 1, wherein the image shift means comprise a processor being fed a sync signal and said velocity signal for generating vertical and horizontal offset signals for said screen when displaying said color component images.

3. The display device as claimed in claim 2, wherein said screen is a cathode ray tube (CRT) display device and said vertical and horizontal offset signals control vertical and horizontal deflections in said CRT display device respectively.

4. The display device as claimed in claim 2, wherein said velocity signal comprises head pitch, roll and yaw rate data.

5. The display device as claimed in claim 3, wherein said offset signals vary continuously over each field to compensate for delay in image presentation due to vertical scan time.

6. The display device as claimed in claim 3, wherein said offset signals vary continuously over each horizontal line scan of each field to roll said images on said display.

7. The display device as claimed in claim 1, wherein said image shift means comprise a relay mirror having an angular orientation with respect to said screen which is adjustable by transducer means.

8. The display device as claimed in claim 7, wherein the image shift means comprise a processor being fed a sync signal and said velocity signal for generating vertical and horizontal offset signals for said transducer means when displaying said color component images.

9. The display device as claimed in claim 8, wherein said offset signals vary continuously over each field to compensate for delay in image presentation due to vertical scan time.

10. The display device as claimed in claim 1, wherein said screen is a digital display, said image shift means comprising vertical and horizontal digital image shift circuits.

11. A method for displaying a simultaneous color video signal on a field sequential color display device for use in displaying an image of an environment comprising the steps of:

generating color component images from said simultaneous color video signal;

sequentially displaying said color component images on a head mounted display screen and providing a color filter for each of said color component images to appear to have a different color, such that a mixing of said color component images as seen by an observer results in the appearance of a normal color image;

determining an angular velocity of a head of said observer; and

shifting said color component images with respect to one another as a function of said velocity to suppress color break-up in said field sequential color display.

12. The method as claimed in claim 11, wherein said step of shifting comprises changing a cathode ray tube (CRT) display horizontal and vertical deflection signals.

13. The method as claimed in claim 12, wherein said velocity comprises head pitch, roll and yaw rate data.

14. The method as claimed in claim 12, wherein said deflection signals are varied continuously over each field to compensate for delay in image presentation due to vertical scan time.

15. The method as claimed in claim 12, wherein said deflection signals are varied continuously over each horizontal line scan of each field to roll said images on said display.

16. The method as claimed in claim 11, wherein said step of shifting comprises adjusting an angular position of a mirror.