Multiple image, single display system and method

• US 4,879,603 A
• Filed: 08/15/1988
• Issued: 11/07/1989
• Est. Priority Date: 08/15/1988
• Status: Expired due to Fees

• Current Assignee: Kaiser Aerospace & Electronics Corporation
• Original Assignee: Kaiser Aerospace & Electronics Corporation
• Inventors: Berman, Arthur L.
• Primary Examiner(s): Britton, Howard W.
• Application Number:
  US07/232,350
• Time in Patent Office: 449 Days
• Field of Search: 358/92, 358/242, 358/142, 358/253
• US Class Current: 348/832
• CPC Class Codes: H04N 5/445 for displaying additional information H04N5/50 takes precedence
• CPC Class Codes: H04N 5/72 Modifying the appearance of television pictures by optical filters or diffusing screens

Abstract

A multiple image, single display system (2) includes a monochromatic display source (4) which provides first and second rapidly alternating visual images (8, 10) which pass through an active polarizer assembly (14). The polarizer assembly includes an image polarizer (20), which polarizes all the light to a left hand circular polarization, and a polarization changer (22) coupled to the display source by a synchronizer 28). The polarization changer switches the polarization of the first image but not the second image. A first user (34) sees the first image, but not the second image, through a right hand circular user polarizer (16) while a second user (36) sees the second image, but not the first image, through a left hand circular user polarizer (18). The user polarizers are wave-length sensitive so they block light only if the light has the same polarization and if the light is the wavelength of the light produced by the display source; the user polarizers are otherwise transparent to visible light. This permits the invention to be used in critical low light situations.

Claims

1. A multiple image, single display system comprising:

a display source providing first and second alternating visual images along a light path at a chosen rate and at first and second wavelengths;

an active polarizer assembly, synchronously coupled to the display source and positioned along the light path, which polarizes the first image with a first polarization orientation and the second image with a second polarization orientation;

a first, wavelength sensitive user polarizer positioned downstream of the polarizer assembly, associated with a first user which blocks transmission of light at about the second wavelength and the second polarization orientation; and

a second, wavelength sensitive user polarizer, positioned downstream of the polarizer assembly, associated with a second user which blocks transmission of light at about the first wavelength and the first polarization orientation;

whereby the first viewer sees the first image but not the second image and the second viewers sees the second image but not the first images without substantially affecting the non-display source vision of the users.

2. The system of claim 1 wherein the first polarization orientation is a circular polarization orientation.

3. The system of claim 1 wherein the first user polarizer includes a cholesteric liquid crystal film.

4. The system of claim 1 wherein the first and second wavelengths are the same.

5. The system of claim 1 wherein the display source includes a cathode ray tube.

6. The system of claim 1 wherein the polarizer assembly includes an image polarizer for initially polarizing both of the first and second images with the first polarization orientation.

7. The system of claim 6 wherein the polarizer assembly includes a polarization charger, positioned downstream of the image polarizer, for changing the polarization of the second image to the second polarization orientation.

8. A multiple image, single display system comprising:

a time sequential display source providing first and second rapidly alternating visual images at a chosen rate along an image path at first and second wavelengths;

an image polarizer positioned along the image path for polarizing the first and second images to a first, circular polarization orientation;

a polarization changer positioned along the image path downstream of the image polarizer for changing the circular polarization orientation of light passing along the light path from the first to a second circular polarization orientation when in a first state and for leaving the circular polarization orientation of said light unchanged when in a second state;

a synchronizer, coupled to the display source and the polarization changer, for switching the polarization changer between the first and second states at the chosen rate synchronous with the provision of the first and second images so the first image passing through the polarization changer has its first circular polarization orientation changed to the second polarization orientation and the circular polarization orientation of the second image is unchanged as it passes through the polarization changer; and

first and second wavelength-sensitive, user polarizers, associated with first and second users respectively, which only blocks transmission of light to the first user which is about the second wavelength and has the second circular polarization orientation and only blocks light to the second user which is about the first wavelength and has the first circular polarization orientation;

whereby the first user does not see the second image and the second user does not see the first image.

9. The system of claim 8 wherein the display source is a monochromatic display source and the first and second wavelength are the same.

10. A method for displaying first and second images on a single display source for simultaneous viewing by first and second viewers, the first viewer viewing only the first image and the second viewer viewing only the second image, comprising the following steps:

alternately projecting first and second visual images at a chosen rate;

intercepting the first and second images by a polarizer assembly;

polarizing the first image with a first polarization orientation by the polarizer assembly;

polarizing the second image with a second polarization orientation by the polarizer assembly;

intercepting the first and second polarized images by first and second user polarizers associated with the first and second users;

blocking transmission of the second polarized image by the first user polarizer so the first viewer views the first image but not the second image; and

blocking transmission of the first polarized image by the second user polarizer so the second viewer views the second image but not the first image.

11. The method of claim 10 wherein the second polarized image blocking step is carried out using a cholesteric liquid crystal film.

12. The method of claim 10 wherein the first image polarizing step includes polarizing the first image with a first circular polarization orientation.

13. The method of claim 10 wherein the projecting step is carried out by alternately projecting the first and second visual images at first and second wavelengths.

14. The method of claim 13 wherein the second polarized image blocking step is carried out by blocking transmission of light which has both the second wavelength and the second polarization orientation so that the first viewer sees the first image but not the second image without substantially affecting the nondisplay source vision of the first viewer.

15. The method of claim 14 wherein the first polarized image blocking step is carried out by blocking transmission of light which has both the first wavelength and the first polarization orientation so that the second viewer sees only the second image without substantially affecting the non-display source vision of the second viewer.