Head-up display system where polarized light from a display impinges on a glass plate containing twisted nematic liquid crystal at the plate's Brewsters angle

• US 5,510,913 A
• Filed: 07/20/1993
• Issued: 04/23/1996
• Est. Priority Date: 07/23/1992
• Status: Expired due to Term

• Current Assignee: Central Glass Company Limited, Nippon Oil Corporation (ENEOS Holdings, Inc.)
• Original Assignee: Central Glass Company Limited, Nippon Oil Corporation (ENEOS Holdings, Inc.)
• Inventors: Hashimoto, Chikara, Itoh, Hiroyuki, Takamatsu, Atsushi, Toyooka, Takehiro
• Primary Examiner(s): Gross, Anita Pellman
• Assistant Examiner(s): Malinowski, Walter J.
• Application Number:
  US08/093,848
• Time in Patent Office: 1,008 Days
• Field of Search: 359/73, 359/65, 359/63, 359/37, 359/487, 359/13, 359/14, 359/15, 359/494
• US Class Current: 349/194
• CPC Class Codes: B32B 17/10036 comprising two outer glass sheets
• CPC Class Codes: B32B 17/10458 Polarization selective transmission
• CPC Class Codes: C09K 19/3809 Polyesters; Polyester derivatives, e.g. polyamides
• CPC Class Codes: C09K 19/3866 containing steroid groups
• CPC Class Codes: C09K 19/408 Polysiloxanes
• CPC Class Codes: G02B 2027/012 comprising devices for attenuating parasitic image effects
• CPC Class Codes: G02B 2027/0194 with combiner of laminated type, for optical or mechanical aspects
• 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 27/283 used for beam splitting or combining
• CPC Class Codes: G02B 5/30 Polarising elements light-modulating devices with active elements G02F1/00

Abstract

A head-up display system for a vehicle includes a front windshield, a display, a polarizing member and an optical rotatory film. The display for displaying an image on the front windshield to be viewed by a driver of the vehicle is disposed such that light therefrom is incident on the front windshield at an angle which is substantially equal to Brewster'"'"'s angle. The polarizing member is disposed between the front windshield and the display for polarizing light from the display. The optical rotatory film serves to rotate the plane of polarization of light polarized by the polarizing member. The optical rotatory film installed on the front windshield includes a liquid crystal high polymer which is in twisted nematic orientation under liquid crystal condition and is in glassy condition at a temperature which is lower than liquid crystal transition point. Thus, double image problem can be eliminated with respect to light having a wide range of wavelengths.

Claims

1. A display system comprising:

a glass plate;

means for displaying an image on said glass plate to be viewed by a viewer of said image, said displaying means being disposed such that light therefrom is incident on said glass plate at an angle which is substantially equal to Brewster'"'"'s angle;

means for polarizing light from said displaying means, said polarizing means being disposed between said glass plate and said displaying means; and

an optical rotatory film for rotating a plane of polarization of light polarized by said polarizing means, said optical rotatory film being installed on said glass plate, said optical rotatory film comprising a liquid crystal high polymer which is in twisted nematic orientation at a temperature which is higher than glass transition point thereof and is in glassy condition at a temperature which is lower than said glass transition point.

2. A display system comprising:

a glass plate;

means for displaying an image on said glass plate to be viewed by a viewer of said image, said displaying means being disposed such that light therefrom is incident on said glass plate at an angle which is substantially equal to Brewster'"'"'s angle;

means for polarizing light from said displaying means, said polarizing means being disposed between said glass place and said displaying means; and

an optical rotatory film for rotating a plane of polarization of light polarized by said polarizing means, said optical rotatory film being installed on said glass plate, said optical rotatory film comprising a liquid crystal high polymer which is in twisted nematic orientation under liquid crystal condition and is in glassy condition at a temperature which is lower than liquid crystal transition point thereof.

3. A display system according to claim 2, wherein said glass plate is made up of a laminated glass pane including an inboard glass sheet, an outboard glass sheet and an intermediate film disposed therebetween, said optical rotatory film is installed between said inboard and outboard glass sheets.

4. A display system according to claim 3, wherein said optical rotatory film is installed between said inboard glass sheet and said intermediate film.

5. A display system according to claim 2, wherein said polarizing means is a S-wave polarizing member.

6. A display system according to claim 2, wherein said polarizing means is a P-wave polarizing member.

7. A display system according to claim 2, wherein said liquid crystal high polymer has a inherent viscosity ranging from 0.05 to 3.0 at a temperature of 30°

C.

8. A display system according to claim 2, wherein said optical rotatory film has a thickness of 0.5 μ

m to 20 μ

m.

9. A display system according to claim 8, wherein said optical rotatory film has a thickness of 1 μ

m to 15 μ

m.

10. A display system according to claim 2, wherein said glass plate is a front windshield of a vehicle, and said viewer is a driver of said vehicle.