Method and device for converting an emission beam from a laser light source into 2-dimensional light

• US 8,317,333 B2
• Filed: 08/08/2011
• Issued: 11/27/2012
• Est. Priority Date: 06/20/2005
• Status: Expired due to Fees

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Kasazumi, Kenichi, Kitaoka, Yasuo, Mizuuchi, Kiminori, Yamamoto, Kazuhisa
• Primary Examiner(s): LUU, THANH X
• Application Number:
  US13/204,925
• Publication Number:
  US 20110292350A1
• Time in Patent Office: 477 Days
• Field of Search: 353/34, 353/37, 353/50, 353/51, 353/82, 353/98, 3592041-2045
• US Class Current: 353/34
• CPC Class Codes: G02B 17/004 Systems comprising a plurality of reflections between two or more surfaces, e.g. cells, resonators multipass arrangements for optical cuvettes G01N21/031; laser resonators H01S3/05
• CPC Class Codes: G02B 26/0808 by means of one or more diffracting elements
• CPC Class Codes: G02B 27/0905 Dividing and/or superposing multiple light beams
• CPC Class Codes: G02B 27/0933 Systems for active beam shaping by rapid movement of an element
• CPC Class Codes: G02B 27/0944 Diffractive optical elements, e.g. gratings, holograms gratings per se G02B5/18; holograms used as optical elements per se G02B5/32
• CPC Class Codes: G02B 27/102 for generating a colour image from monochromatic image signal sources
• CPC Class Codes: G02B 27/1046 for use with transmissive spatial light modulators
• CPC Class Codes: G02B 27/1093 for use with monochromatic radiation only, e.g. devices for splitting a single laser source
• CPC Class Codes: G02B 27/145 having sequential partially reflecting surfaces
• CPC Class Codes: G02B 27/149 using crossed beamsplitting surfaces, e.g. cross-dichroic cubes or X-cubes
• CPC Class Codes: G03B 21/14 Details
• CPC Class Codes: G03B 21/2033 LED or laser light sources
• CPC Class Codes: G03B 21/208 Homogenising, shaping of the illumination light
• CPC Class Codes: G03B 33/12 using beam-splitting or beam-combining systems, e.g. dichroic mirrors
• CPC Class Codes: H04N 9/3161 using laser light sources using laser beams scanning the display screen H04N9/3129

Abstract

A 2-dimensional beam scan unit reflects emission beams from a red laser light source, a green laser light source and a blue laser light source and scans in a 2-dimensional direction. Diffusion plates diffuse the respective light beams scanned in the 2-dimensional direction to introduce them to corresponding spatial light modulation elements. The respective spatial light modulation elements modulate the respective lights in accordance with video signals of the respective colors. A dichroic prism multiplexes the lights of the three colors after the modulation and introduces the multiplexed lights to a projection lens so that a color image is displayed on a screen. Since the 2-dimensional light emitted from the beam scan unit is diffused to illuminate the spatial light modulation element, it is possible to change the optical axis of the beam emerging from the light diffusion member for irradiating the spatial light modulation element moment by moment, thereby effectively suppressing speckle noise.

Claims

1. A 2-dimensional image display device comprising:

at least one laser light source;

a beam scan unit configured to convert an emission beam from said laser light source into a 2-dimensional light while scanning the emission beam at least in a 1-dimensional direction;

a spatial light modulation element configured to spatially modulate the light scanned by said beam scan unit; and

a light diffusion member disposed between said beam scan unit and said spatial light modulation element for diffusing the 2-dimensional light emerging from said beam scan unit,

wherein said laser light source includes first, second and third laser light sources for generating red, green and blue colors, respectively, and

wherein emission beams from said first, second and third laser light sources are incident on said beam scan unit at mutually different angles.

2. A 2-dimensional image display device according to claim 1, wherein said light diffusion member is one of a plurality of diffusion members and said spatial light modulation element is one of a plurality of spatial light modulation elements, said plurality of diffusion members and said plurality of spatial light modulation elements being in a one-to-one correspondence with said laser light sources.

3. A 2-dimensional image display device comprising:

at least one laser light source;

a beam scan unit configured to convert an emission beam from said laser light source into a 2-dimensional light while scanning the emission beam at least in a 1-dimensional direction;

a spatial light modulation element configured to spatially modulate the light scanned by said beam scan unit; and

a light diffusion member disposed between said beam scan unit and said spatial light modulation element for diffusing the 2-dimensional light emerging from said beam scan unit,

wherein a light beam diameter S on the light diffusion member satisfies a relationship S>

L·

θ

−

d if θ

, L and d denote the diffusion angle of said light diffusion member, a distance between said light diffusion member and said spatial light modulation element and the spacing between adjacent light beams emerging from said beam scan unit on said spatial light modulation element, and

wherein the adjacent light beams have been split by a dimensional beam splitting grating.