Display device

• US 7,019,798 B2
• Filed: 01/31/2003
• Issued: 03/28/2006
• Est. Priority Date: 02/25/2002
• Status: Active Grant

• Current Assignee: Minolta Corporation Limited (Konica Minolta Inc.)
• Original Assignee: Minolta Corporation Limited (Konica Minolta Inc.)
• Inventors: Endo, Takeshi, Kasai, Ichiro
• Primary Examiner(s): Schechter, Andrew
• Assistant Examiner(s): Wang, George Y.
• Application Number:
  US10/355,804
• Publication Number:
  US 20030179423A1
• Time in Patent Office: 1,152 Days
• Field of Search: 349/61, 349/68, 349/113, 349/114, 359/15, 359/20
• US Class Current: 349/61
• CPC Class Codes: G02B 2027/0118 comprising devices for improving the contrast of the display / brillance control visibility
• CPC Class Codes: G02B 2027/0174 holographic
• CPC Class Codes: G02B 2027/0178 Eyeglass type eyeglass details G02C
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 5/203 having holographic or diffractive elements diffraction gratings per se G02B5/18; holographic elements per se G02B5/32; generating the spectrum using diffraction elements G01J3/18
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: G02F 1/133621 providing coloured light G02F1/133617, G02F1/133533 take precedence
• CPC Class Codes: G02F 1/133622 Colour sequential illumination
• CPC Class Codes: G02F 2203/34 Colour display without the use of colour mosaic filters

Abstract

A display device has a plurality of light emitting elements for emitting lights, a display element for modulating the light emitting from the plurality of light emitting elements so as to convert it to an image light showing an optical image, a reflection type hologram element, having a positive optical power with respect to the lights from the plural light emitting elements, for diffracting and reflecting the lights from the plural light emitting elements to approximately one direction so as to guide the diffracted and reflected lights to the display element; and an enlarging optical system for forming an enlarged image of the optical image converted by the lights from the image display element. The plural light emitting elements are positioned in a plane approximately vertical to an optical path of the lights diffracted and reflected by the hologram element. The hologram element is tilted to a direction facing the plural light emitting elements with respect to the optical path of the lights diffracted and reflected by the hologram element.

Claims

1. A display device comprising:

a plurality of light emitting elements for emitting lights;

a display element for modulating the light emitting from the plurality of light emitting elements so as to convert it to an image light showing an optical image;

a reflection type hologram element, having a positive optical power with respect to the lights from the plural light emitting elements, for diffracting and reflecting the lights from the plural light emitting elements to approximately one direction so as to guide the diffracted and reflected lights to the display element; and

an enlarging optical system for forming an enlarged image of the optical image converted by the lights from the image display element,

wherein the plural light emitting elements are positioned in a plane such that an optical path of the lights diffracted and reflected by the hologram element is approximately orthogonal to the plane, and

wherein the hologram element is tilted to a direction facing the plural light emitting elements with respect to the optical path of the lights diffracted and reflected by the hologram element.

2. The display device as claimed in claim 1, wherein the plural light emitting elements emit lights with different wavelengths and the hologram element has a peak of diffraction and reflection efficiency with respect to the wavelengths of the lights emitted from the plural light emitting elements.

3. The display device as claimed in claim 1, wherein the display element is of a reflection type which reflects and modulates the light, and reflects the lights diffracted and reflected by the hologram element to a direction with an angle difference with respect to an incident direction and the hologram element allows the lights from the display element to transmit so as to guide them to the enlarging optical system.

4. The display device as claimed in claim 1, wherein the enlarging optical system is an eyepiece optical system.

5. The display device as claimed in claim 1, wherein the display device is a transmission type liquid crystal display.

6. The display device as claimed in claim 1, wherein the display device is a reflection type liquid crystal display.

7. The display device as claimed in claim 1, further comprising:

a prism provided between the hologram element and the display device.

8. The display device as claimed in claim 1, further comprising:

two polarizing plates provided on the optical path.

9. The display device as claimed in claim 1, further comprising:

a polarization selecting element provided on the optical path.

10. A display device as claimed in claim 4, wherein the eyepiece optical system comprises the eyepiece lens of eyeglass.

11. A display device as claimed in claim 10, further comprising:

a hologram element diffracting and reflecting the light from the display element and guiding it to an eye E of a user, the hologram element serving as an eyepiece optical system.