LASER PROJECTOR

• US 20120147334A1
• Filed: 06/20/2011
• Published: 06/14/2012
• Est. Priority Date: 06/22/2010
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Mizushima, Tetsuro, Itoh, Tatsuo, Kasazumi, Kenichi, Nakayama, Kenji
• Granted Patent: US 8,801,189 B2
• Time in Patent Office: Days
• US Class Current: 353/31
• CPC Class Codes: G02B 13/007 the beam folding prism having at least one curved surface
• CPC Class Codes: G02B 27/0933 Systems for active beam shaping by rapid movement of an element
• CPC Class Codes: G02B 27/141 using dichroic mirrors
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G03B 21/14 Details
• CPC Class Codes: G03B 21/2006 characterised by the light source
• 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: H04N 9/3161 using laser light sources using laser beams scanning the display screen H04N9/3129
• CPC Class Codes: H04N 9/3164 using multiple light sources

Abstract

There is provided a laser projector, including: a laser source section for emitting laser beams; a spatial light modulator which modulates the laser beams to generate image light; a projector lens from which the image light is emitted; a beam shaper which shapes the laser beams into a shape of the spatial light modulator; and a pupil uniformizer which makes a light intensity distribution uniform at an exit pupil of the projector lens, wherein the pupil uniformizer is situated between the laser source section and the beam shaper.

Claims

1. A laser projector, comprising:

a laser source section configured to emit laser beams;

a spatial light modulator which modulates the laser beams to generate image light;

a projector lens from which the image light is emitted;

a beam shaper configured to shape the laser beam into a shape of the spatial light modulator; and

a pupil uniformizer which makes a light intensity distribution uniform at an exit pupil of the projector lens, wherein

the pupil uniformizer is situated between the laser source section and the beam shaper.

2. The laser projector according to claim 1, wherein

the beam shaper is in a conjugated relationship with the exit pupil, and

the pupil uniformizer makes an intensity distribution of incident light to the beam shaper uniform.

3. The laser projector according to claim 1, wherein

the pupil uniformizer includes a cluster of first element lenses which make the light intensity distribution uniform,

the beam shaper includes a cluster of second element lenses which shape the laser beams into the shape of the spatial light modulator,

the first element lenses spread the laser beams in response to a divergent angle of the first element lenses to make the light intensity distribution uniform, and

the second element lenses spread the laser beams in response to a divergent angle of the second element lenses to shape the laser beam.

4. The laser projector according to claim 3, wherein

each of the first and second element lenses has a concave lens.

5. The laser projector according to claim 3, wherein

each of the first and second element lenses has a curved surface to spread the laser beams, and

the curved surface has a curvature distribution which decreases toward a contour of the curved surface.

6. The laser projector according to claim 5, further comprising:

a light diffuser which diffuses the laser beams and makes the diffused laser beams incident to the spatial light modulator, wherein

the laser beams, which are emitted from the beam shaper and then spread and superimposed on each other in response to the curvature distribution, are incident to the light diffuser.

7. The laser projector according to claim 1, further comprising:

a condenser lens and a field lens, wherein

the spatial light modulator is provided as a reflective type spatial light modulator, and

the laser beams emitted from the beam shaper illuminate the reflective type spatial light modulator through the condenser lens and the field lens, and then are reflected by the reflective type spatial light modulator to reach the projector lens through the field lens.

8. The laser projector according to claim 3, wherein

a maximum numerical aperture of the second element lenses is no less than 0.3.

9. The laser projector according to claim 6, further comprising:

a movement mechanism which causes a perpendicular motion of the beam shaper to an optical axis defined between the laser source section and the spatial light modulator, wherein

if the laser beams are incident to the spatial light modulator through the light diffuser, the movement mechanism moves the beam shaper with smaller amplitude than a minimum sectional dimension of the second element lenses.

10. The laser projector according to claim 1, wherein

the laser source section includes a red laser source, which emits a red laser beam, a green light source, which emits a green laser beam, and a blue laser source, which emits a blue laser beam, and

a sectional area of the red laser beam incident to the beam shaper is smaller than sectional areas of the green and blue laser beams incident to the beam shaper.

11. The laser projector according to claim 1, wherein

a relationship of F#<

f/D<

2×

F# is satisfied where F# is an f-number of the projector lens, D is a longitudinal beam diameter of the laser beams incident to the beam shaper, and f is a focal distance of a lens group through which the laser beams incident to the beam shaper pass up to the spatial light modulator.

12. The laser projector according to claim 3, wherein

the pupil uniformizer includes a surface on which there is a protrusion.