Hologram screen and a method of producing the same

• US 6,597,477 B2
• Filed: 03/26/2002
• Issued: 07/22/2003
• Est. Priority Date: 07/07/1998
• Status: Expired due to Fees

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Shiozawa, Masahiro, Takada, Kenichiro
• Primary Examiner(s): Robinson, Mark A.
• Assistant Examiner(s): Boutsikaris, Leo
• Application Number:
  US10/106,777
• Publication Number:
  US 20020154348A1
• Time in Patent Office: 483 Days
• Field of Search: 359/15, 359/16, 359/1, 359/599, 396/288
• US Class Current: 359/15
• CPC Class Codes: G02B 2027/0118 comprising devices for improving the contrast of the display / brillance control visibility
• CPC Class Codes: G02B 27/0103 comprising holographic elements
• CPC Class Codes: G02B 5/32 Holograms used as optical elements

Abstract

In a hologram screen for reproducing an image based on an output light obtained by scattering and diffusing an image light from an image projector, when a white light (image light) is projected on the hologram screen; and when a distance between two points at optional two points A and B on a surface of the hologram screen is given by 20 cm or less, and a value of the CIE 1976 chromaticity coordinate (u′, v′) at the point A is given by (u′_A, v′_A) and the value of the CIE 1976 chromaticity coordinate (u′, v′) at the point B is given by (u′_B, v′_B); the output light perpendicularly from the surface of the hologram screen has a color distribution in which a color difference Δu′v′ between two points A and B is derived from the following formula (1) and given by 0.06 or less, where, the formula (1) is expressed by,

Δu′v′=[(u′_A−u′_B)²+(v′_A−v′_B)²]^1/2  (1)

Further, the output light, which is output to a viewpoint defined by the following formula (2) from the surface of the hologram screen, has the color distribution in which a color difference Δu′v′ between two points A and B is derived from the above formula (1) and given by 0.01 or less, where, the formula (2) is expressed by,

H/2L=0.1  (2)

in the formula (2), L is a distance between the viewpoint and a center of the hologram screen, and H is a length of the hologram screen in the direction of the height.

Claims

1. A hologram screen for reproducing an image based on an output light obtained by scattering and diffusing and image light from an image projector, characterized in that;

said hologram screen present an optical spectrum whose bandwidth is 100 nm or more; and

said hologram screen is comprised of a hologram element which is made by forming an interference fringe on a photosensitive material, said interference fringe being formed by irradiating an object light and a reference light onto said light sensitive material, said object light being made of a light diffused by a light diffusion body having a large diffusion angle and said reference light being made of a non-diffused light, where said light diffusion angle of the light diffusion body is set to 9 degrees or more such that the half bandwidth of said optical spectrum of the hologram screen is 100 nm or more.

2. A hologram screen as claimed in claim 1, wherein the light diffusion angle of the hologram screen is defined by an angle in which the light diffusion angle of the hologram screen is 10°

or more.

3. A hologram screen as claimed in claim 1 wherein said light sensitive material has a thickness of 1-20 μ

n.

4. A hologram screen as claimed in claim 1, wherein said image light is obtained from a white light source.

5. A hologram screen as claimed in claim 1, wherein said optical spectrum of the hologram screen is measured from a light diffracted in a direction to an observer.

6. A hologram screen for reproducing an image based on an output light obtained by scattering and diffusing an image light from an image projector, characterized in that;

said hologram screen present an optical spectrum whose bandwidth is 100 nm or more; and

said hologram screen is comprised of a hologram element which is made by forming an interference fringe on a photosensitive material, said interference fringe being formed by irradiating object lights and reference lights onto said light sensitive material, said object lights being made of diffused lights which are obtained irradiating a plurality of lights incident onto a light diffusion body at different angles and said reference lights being made of non-diffused lights, where said light diffusion angle of the light diffusion body is set to 9 degrees or more such that the half bandwidth of said optical spectrum of the hologram screen is 100 nm or more.

7. A hologram screen as claimed in claim 6, wherein said image light is obtained from a white light source.

8. A hologram screen as claimed in claim 6, wherein said optical spectrum of the hologram screen is measured from a light diffracted in a direction to an observer.