Display system where polarized light impinges on platelike laminate at brewster's angle or emerges therefrom at angle equal thereto

• US 6,327,084 B1
• Filed: 06/30/1998
• Issued: 12/04/2001
• Est. Priority Date: 06/30/1997
• Status: Expired due to Fees

• Current Assignee: Central Glass Company Limited
• Original Assignee: Central Glass Company Limited
• Inventors: Nishikawa, Shinji, Kobayashi, Kazuya, Asakura, Motoh
• Primary Examiner(s): Shafer, Ricky D.
• Application Number:
  US09/107,404
• Time in Patent Office: 1,253 Days
• Field of Search: 359/487, 359/493, 359/494, 359/495, 359/499, 359/501, 359/630, 359/631, 359/13, 353/13, 353/14, 345/7, 349/11
• US Class Current: 359/485.02
• CPC Class Codes: G02B 2027/012 comprising devices for attenuating parasitic image effects
• CPC Class Codes: G02B 27/01 Head-up displays
• CPC Class Codes: G02B 27/0101 characterised by optical features G02B27/0172 takes precedence
• CPC Class Codes: G02B 5/30 Polarising elements light-modulating devices with active elements G02F1/00
• CPC Class Codes: G02B 5/3066 involving the reflection of light at a particular angle of incidence, e.g. Brewster's angle

Abstract

The invention relates to a display system where polarized light rays from a display device impinge on a laminate at Brewster'"'"'s angle or emerge therefrom at an angle equal to Brewster'"'"'s angle. This laminate is a combination of a transparent platelike object and a functional film that is an optical rotatory film or a semitransparent film. The platelike object has a front major surface, facing the display device, and a back major surface. The display device has a polarizing member for polarizing light rays of the display device into S-wave or P-wave light rays. According to a first embodiment of the invention, the optical rotatory film is formed on the front or back major surface of the platelike object or in an inside of the platelike object, and S-wave light rays from the polarizing member are thrown against the front major surface of the laminate. With this, a part of the S-wave light rays is reflected from the front major surface of the laminate toward a viewer. The rest of the S-wave light rays is transmitted in the platelike object and converted into P-wave light rays by the optical rotatory film. Then, substantially all of the P-wave light rays emerge from the back major surface of the laminate into the air at an angle substantially equal to Brewster'"'"'s angle of the platelike object or the optical rotatory member, which borders on the back major surface of the laminate. Thus, the double image phenomenon does not arise.

Claims

1. A display system comprising:

a transparent platelike object having a first and a second major surface opposed to each other;

an optical rotatory film for rotating a plane of polarization of light rays, said optical rotatory film being formed on said first or said second major surface of said platelike object or in an inside of said platelike object, a combination of said transparent platelike object and said optical rotatory film constituting a platelike laminate, said platelike laminate having a front major surface and a back major surface that is an interface between said platelike laminate and an air, and

a display device for providing, against said front major surface of said platelike laminate, light rays that are intended to be viewed by a viewer, said display device having a polarizing member for polarizing said light rays into S-wave light rays; and

wherein said front major surface of said platelike laminate faces said display device such that a part of said S-wave light rays from said polarizing member is reflected from said front major surface of said platelike laminate towards one-eye point of said viewer and that a remainder of said S-wave light rays is transmitted in said platelike laminate and is converted by said optical rotatory film into P-wave light rays,

wherein said back major surface of said platelike laminate is curved such that substantially all of said P-wave light rays emerge from said back major surface of said platelike laminate into said air at an angle that is substantially equal to Brewster'"'"'s angle of one member selected from said optical rotatory film and said platelike object, said one member bordering on said back major surface of said platelike laminate, said angle being defined between a direction of propagation of said P-wave light ray in said air and a line that is perpendicular to said back major surface of said platelike laminate at a point of emergence of said P-wave light ray from said platelike laminate into said air.

2. A display system according to claim 1, wherein said platelike object has a thickness of up to about 2 mm, and wherein said front major surface of said platelike laminate is curved in parallel with said back major surface of said platelike laminate.

3. A display system according to claim 1, wherein said optical rotatory film is selected from the group consisting of a liquid crystal polymer film, a transparent birefringent film, and a λ

/2 phase film.

4. A display system according to claim 1, wherein said transparent platelike object is made of polymethyl methacrylate.

5. A display system according to claim 1, which is an automotive head-up display system.

6. A display system according to claim 1, wherein said display device is selected from the group consisting of a cathode-ray tube, a fluorescent display tube, and a liquid crystal display.

7. A display system according to claim 1, wherein said platelike object is a laminate of first and second plates.

8. A display system according to claim 7, wherein said optical rotatory film is interposed between said first and second plates.

9. A display system according to claim 7, wherein said platelike object has an interlayer film interposed between said first and second plates.