LASER ILLUMINATING DEVICE AND IMAGE DISPLAY DEVICE

• US 20100053565A1
• Filed: 03/14/2008
• Published: 03/04/2010
• Est. Priority Date: 03/19/2007
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Shikii, Shinichi, Kasazumi, Kenichi, Itoh, Tatsuo, Mizushima, Tetsuro
• Granted Patent: US 8,192,030 B2
• Time in Patent Office: Days
• US Class Current: 353/38
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G02B 3/0006 Arrays G02B3/02, G02B5/188 take precedence
• 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: H04N 9/3102 using two-dimensional electronic spatial light modulators micromechanical modulators as such G02B26/0833; liquid crystal modulators as such G02F1/13
• CPC Class Codes: H04N 9/3152 for shaping the light beam beam shaping per se G02B27/09
• CPC Class Codes: H04N 9/3161 using laser light sources using laser beams scanning the display screen H04N9/3129

Abstract

An object of the invention is to provide a laser illuminating device and an image display device that enable to remove speckle noises in a diffraction field and an image field, uniformly illuminate an illumination plane, and realize miniaturization. A laser illuminating device 100 includes a laser light source 3, a first lens 1 including a plurality of microlenses 10 each having a predetermined numerical aperture in an in-plane direction, each of the microlenses 10 being adapted to expand laser light emitted from the laser light source 3 to thereby superimpose the laser light transmitted through each of the microlenses 10; and a second lens 2 having an effective diameter larger than an effective diameter of the first lens 1, and for compensating for a divergence angle of the laser light expanded by each of the plurality of the microlenses 10.

Claims

1-18. -18. (canceled)

19. A laser illuminating device comprising:

a laser light source;

a first lens including a plurality of microlenses each having a predetermined numerical aperture in an in-plane direction, each of the plurality of the microlenses being adapted to expand laser light emitted from the laser light source to thereby superimpose the laser light transmitted through each of the microlenses; and

a second lens having an effective diameter larger than an effective diameter of the first lens, and for compensating for a divergence angle of the laser light expanded by each of the plurality of the microlenses, wherein

the laser light source emits a plurality of the laser light having wavelengths different from each other, and

the laser illuminating device satisfies the relations expressed by the formulas (1) and (2)

d>

10×

(λ

l−

λ

s) 

 

(1)

d<

R1/3 

 

(2)

where λ

l is a longest wavelength to be used in the laser light source, λ

s is a shortest wavelength to be used in the laser light source, R1 is the effective diameter of the first lens, and d is a minimum pitch of the microlens.

20. The laser illuminating device according to claim 19, further comprising

a moving mechanism for moving the first lens in a plane direction perpendicular to an optical axis.

21. The laser illuminating device according to claim 20, wherein

the moving mechanism has a maximum amplitude larger than a maximum pitch of the microlens in a moving direction thereof.

22. The laser illuminating device according to claim 19, further comprising

a light diffuser disposed on a laser light incident side of the second lens and for diffusing the laser light expanded by each of the plurality of the microlenses.

23. The laser illuminating device according to claim 19, wherein

the laser illuminating device satisfies the relations expressed by the formulas (3) through (5)

L−

R1/NAm<

BF2<

L+R1/NAm 

 

(3)

R2>

2×

R1 

 

(4)

R2<

4×

L×

NAm 

 

(5)

where L is a distance between the first lens and the second lens, R1 is the effective diameter of the first lens, R2 is the effective diameter of the second lens, BF2 is a back focus distance of the second lens, and NAm is the numerical aperture of the microlens.

24. The laser illuminating device according to claim 19, wherein

the laser light source emits a plurality of the laser light having wavelengths different from each other, and

the plurality of the laser light is coaxially aligned for incidence into the first lens.

25. The laser illuminating device according to claim 19, wherein

each of the microlenses includes

a first cylindrical lens portion formed on a laser light incident surface of the microlens, and

a second cylindrical lens portion having a numerical aperture different from a numerical aperture of the first cylindrical lens portion, and formed on a laser light exit surface of the microlens in a direction orthogonal to the first cylindrical lens portion.

26. The laser illuminating device according to claim 25, wherein

the numerical aperture of the first cylindrical lens portion is larger than the numerical aperture of the second cylindrical lens portion.

27. The laser illuminating device according to claim 19, wherein

the plurality of the microlenses have the respective predetermined numerical apertures in the in-plane direction, and

at least one of the plurality of the microlenses has a lens diameter different from a lens diameter of the other ones of the plurality of the microlenses.

28. The laser illuminating device according to claim 19, wherein

the shape of each of the plurality of the microlenses is changed, as the each microlens is distanced from an optical axis of the laser light to allow the first lens as a whole to have a lens function.

29. The laser illuminating device according to claim 19, wherein

each of the plurality of the microlenses includes a convex lens portion and a concave lens portion having a numerical aperture identical to a numerical aperture of the convex lens portion, and

the convex lens portions and the concave lens portions are alternately and sequentially arranged in the in-plane direction.

30. The laser illuminating device according to claim 29, wherein

the plurality of the microlenses include:

a first microlens having a convex cylindrical lens portion with a convex surface on a laser light incident surface of the microlens, and the convex cylindrical lens portion on a laser light exit surface of the microlens;

a second microlens having the convex cylindrical lens portion on a laser light incident surface of the microlens, and a concave cylindrical lens portion with a concave surface on a laser light exit surface of the microlens;

a third microlens having the concave cylindrical lens portion on a laser light incident surface of the microlens, and the convex cylindrical lens portion on a laser light exit surface of the microlens; and

a fourth microlens having the concave cylindrical lens portion on a laser light incident surface of the microlens, and the concave cylindrical lens portion on a laser light exit surface of the microlens, and

a diffusing direction of the laser light through the convex cylindrical lens portion on the laser light incident surface and the concave cylindrical lens portion on the laser light incident surface, and a diffusing direction of the laser light through the convex cylindrical lens portion on the laser light exit surface and the concave cylindrical lens portion on the laser light exit surface are orthogonal to each other.

31. An image display device comprising:

the laser illuminating device of claim 19; and

a light modulator disposed on a laser light exit side of the second lens, and for modulating the laser light exiting from the second lens.

32. The image display device according to claim 31, further comprising

an image forming lens disposed between the laser light source and the first lens, and for forming a light source image of the laser light source on a central portion of the light modulator.

33. The image display device according to claim 31, wherein

a ratio of the numerical apertures between the plurality of the microlenses in the in-plane direction is identical to an aspect ratio of the light modulator.