Optical projector and image display apparatus using the same

• US 7,581,838 B2
• Filed: 08/03/2007
• Issued: 09/01/2009
• Est. Priority Date: 12/19/2003
• Status: Active Grant

• Current Assignee: Maxell, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Yoshikawa, Hiroki, Hirata, Koji, Ohishi, Tetsu, Imafuku, Daisuke
• Primary Examiner(s): Dowling; William C
• Application Number:
  US11/833,855
• Publication Number:
  US 20070273969A1
• Time in Patent Office: 760 Days
• Field of Search: 353/31, 353/33, 353/34, 353/37, 353/122, 353/20, 353/69, 353/102, 353/121, 349/5, 349/7, 349/8, 349/9, 349117-121, 349/162, 359/5, 359/7
• US Class Current: 353/69
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G03B 21/005 Projectors using an electronic spatial light modulator but not peculiar thereto

Abstract

Image disturbance called speckle noise occurs when an image generator has a small effective screen size and a projection lens has a small effective diameter. The present invention is intended to reduce speckle noise. In an optical projector, a viewing angle enlarging ember (60) for enlarging viewing angle or a scattering member (28) for scattering image light is disposed near an image display device (18), such as a liquid crystal panel. Speckle noise can be reduced, suppressing the deterioration of resolution and contrast.

Claims

1. An image display apparatus comprising:

a light source;

an image display device capable of forming an image by modulating light emitted by the light source;

a projection lens for projecting the image formed by the image display device on a screen in an enlarged image; and

a viewing angle enlarging member disposed on either of entrance and exit sides of the image display device or on both the entrance and the exit side of the image display device;

wherein the viewing angle enlarging member corrects image light representing the image formed by the image display device such that viewing angle is enlarged and collimation of a light beam transmitted from the image display device is eased, to reduce a speckle noise on the screen.

2. The image display apparatus according to claim 1, wherein viewing angle enlarging member is a film having different refractive indices with the S-wave and the P-wave.

3. An optical projector comprising:

an image display device;

an optical element for projecting an image formed by the image display device in an enlarged image; and

a viewing angle enlarging member disposed near the image display device to enlarge viewing angle and to ease collimation of a light beam transmitted from the image display device such that a speckle noise on a screen on which the image formed by the image display is projected is reduced.

4. An image display apparatus comprising:

an image display device;

an optical element for projecting an image formed by the image display device in an enlarged image;

a rear projection screen on which the optical element projects the enlarged image; and

a viewing angle enlarging member disposed near the image display device to reduce speckle noise on the rear projection screen by enlarging a viewing angle and easing collimation of a light beam transmitted from the image display device.