Illuminating optical unit in image display unit, and image display unit

• US 6,897,992 B2
• Filed: 10/06/2003
• Issued: 05/24/2005
• Est. Priority Date: 10/28/2002
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Kikuchi, Hiroki
• Primary Examiner(s): Ben, Loha
• Application Number:
  US10/678,308
• Publication Number:
  US 20040109219A1
• Time in Patent Office: 596 Days
• Field of Search: 359/237, 359/238, 359/246, 359/276, 359/277, 359/279, 359/290, 359/569, 359/621, 359/622, 385/146, 345/7, 345/88, 372/9, 372/103, 372/107, 353/31, 353/84, 355/53
• US Class Current: 359/237
• CPC Class Codes: G02B 26/0808 by means of one or more diffracting elements
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G02B 5/1828 having means for producing variable diffraction controlling the direction of light by means of one or more diffracting elements G02B26/0808; acousto-optical elements G02F1/11, G02F1/33; electro- or magneto-optical diffraction G02F1/292, G02F1/2955
• CPC Class Codes: H04N 5/7416 involving the use of a spatial light modulator, e.g. a light valve, controlled by a video signal
• CPC Class Codes: H04N 9/3129 scanning a light beam on the display screen scanning a light beam on a screen in displays other than projection devices G09G3/02; scanning systems in general G02B26/10; projectors using laser light sources in general H04N9/3161

Abstract

Disclosed is an illuminating optical unit in an image display unit for displaying an image by irradiating a GLV (spatial modulation device) with a laser beam and modulating the laser beam based on an image signal inputted to the GLV, which includes a polarized light rotation means for equally dividing a polarized light component of the laser beam into a P polarized light component and an S polarized light component, a polarized light beam splitter for separating from each other the P polarized light component and the S polarized light component equally divided by the polarized light rotation means, and an optical path difference generation means for generating an optical path difference not less than the coherence length of the laser beam between the laser beam of the P polarized light component and the laser beam of the S polarized light component.

Claims

1. An illuminating optical unit in an image display unit for forming an image by irradiating a spatial modulation device with a laser beam and modulating said laser beam based on an image signal inputted to said spatial modulation device, comprising:

polarized light rotation means for equally dividing a polarized light component of said laser beam into a P polarized light component and an S polarized light component;

polarized light separation means for separating from each other said P polarized light component and said S polarized light component equally divided by said polarized light rotation means; and

optical path difference generation means for generating an optical path difference not less than the coherence length of said laser beam between a laser beam of said P polarized light component and a laser beam of said S polarized light component.

2. The illuminating optical unit in an image display unit as set forth in claim 1, wherein said polarized light separation means and said optical path difference generation means are constituted in the form of one prism.

3. The illuminating optical unit in an image display unit as set forth in claim 1, comprising:

beam intensity separation means for separating the intensity of said laser beam to form two or more laser beams parallel to each other and generating an optical path difference not less than the coherence length of said laser beam between said two or more separated laser beams.

4. The illuminating optical unit in an image display unit as set forth in claim 3, wherein

the absolute value of the difference between said optical path difference generated by said optical path difference generation means and said optical path difference generated by said beam intensity separation means is not less than said coherence length.

5. The illuminating optical unit in an image display unit as set forth in claim 1, wherein

said spatial modulation device is a grating light valve.

6. An image display unit for displaying an image by irradiating a spatial modulation device with a laser beam and modulating said laser beam based on an image signal inputted to said spatial modulation device, wherein

illuminating optical unit for irradiating said spatial modulation device with said laser beam comprises:

polarized light rotation means for equally dividing a polarized light component of said laser beam into a P polarized light component and an S polarized light component;

polarized light separation means for separating from each other said P polarized light component and said S polarized light component equally divided by said polarized light rotation means; and

optical path difference generation means for generating an optical path difference not less than the coherence length of said laser beam between a laser beam of said P polarized light component and a laser beam of said S polarized light component.

7. The image display unit as set forth in claim 6, wherein

said polarized light separation means and said optical path difference generation means are constituted in the form of one prism.

8. The image display unit as set forth in claim 6, comprising:

beam intensity separation means for separating the intensity of said laser beam to form two or more laser beams parallel to each other and generating an optical path difference not less than the coherence length of said laser beam between said two or more separated laser beams.

9. The image display unit as set forth in claim 8, wherein

the absolute value of the difference between said optical path difference generated by said optical path difference generation means and said optical path difference generated by said beam intensity separation means is not less than said coherence length.

10. The image display unit as set forth in claim 6, wherein

said spatial modulation device is a grating light valve.