Illuminating optical system having multiple light sources and lenticular arrays for use with a projection-type display unit

• US 6,402,325 B1
• Filed: 04/13/2000
• Issued: 06/11/2002
• Est. Priority Date: 04/16/1999
• Status: Expired due to Term

• Current Assignee: Fujinon Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Optical Co. Ltd (Fujifilm Holdings Corporation)
• Inventors: Yamamoto, Chikara
• Primary Examiner(s): Adams, Russell
• Assistant Examiner(s): KOVAL, MELISSA J
• Application Number:
  US09/548,628
• Time in Patent Office: 789 Days
• Field of Search: 353/38, 353/20, 353/94, 353/32, 353/48, 353/102, 349/5, 349/8, 349/9
• US Class Current: 353/94
• CPC Class Codes: G02B 27/0927 Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat
• CPC Class Codes: G02B 27/0961 Lens arrays lens arrays per se G02B3/0006
• CPC Class Codes: G02B 3/005 arranged along a single direction only, e.g. lenticular sheets G02B3/0043 takes precedence
• CPC Class Codes: G02B 3/0062 Stacked lens arrays, i.e. refractive surfaces arranged in at least two planes, without structurally separate optical elements in-between
• CPC Class Codes: G02B 30/54 the 3D volume being generated by moving a 2D surface, e.g. by vibrating or rotating the 2D surface
• CPC Class Codes: G03B 21/2013 Plural light sources
• CPC Class Codes: G03B 21/2073 Polarisers in the lamp house peculiar to electronic spatial light modulators H04N9/3197
• 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 9/3105 for displaying all colours simultaneously, e.g. by using two or more electronic spatial light modulators simultaneous projection in colour photography G03B33/10; beam splitting or combining systems per se G02B27/10
• CPC Class Codes: H04N 9/3164 using multiple light sources

Abstract

An optical illumination system for a projection-type display unit is disclosed wherein multiple light sources are oriented so as to cause the optical axes of their emitted light beams to be non-parallel to one another and to overlap at a first lenticular lens array of an integrator section. The function of the integrator section is to make the light from the multiple light sources even, and to serve as a secondary light source in the projection-type display unit. The overlapping of the light beams on the first lenticular lens array of the integrator allows the optical illumination system to be more compact in three dimensions. It also allows the diameter of a polarization converter and a field lens to be made smaller. Thus, production costs are reduced without reducing the brightness of a projected image.

Claims

1. An illuminating optical system comprising:

a light source device having multiple light sources, each emitting a light beam centered about an optical axis of an associated light source; and

an integrator section that is illuminated by the light source device, said integrator section including two lenticular lens arrays arranged along a light path, one nearer the light source device than the other, each having multiple lens regions which together cause the light intensity distribution that is transmitted by the integrator section to be more uniform than light incident on the integrator section from said light source device;

wherein

at least two of the multiple light sources are oriented so as to cause the optical axes of the emitted light beams to be non-parallel to one another and directed so that the emitted light beams partially overlap at the lenticular lens array nearer the light source device; and

each lens array element of the lenticular lens array which is farther from the light source device is smaller in area in those regions which receive light from a region of the lenticular lens array nearer the light source device and are illuminated by overlapping light beams as compared with those regions which receive light from a region of the lenticular lens array nearer the light source device and are illuminated by light from only a single light source device.

2. The illuminating optical system of claim 1, wherein each lens array element of the lenticular lens array which is farther from the light source device is rectangular in form, the ratio of height versus width of the rectangles varying depending on whether the lens array element receives light from a region of the lenticular lens array nearer the light source device that is illuminated by overlapping light beams.

3. The illuminating optical system of claim 1, and further including a polarization converter which converts non-polarized light to polarized light and is positioned between the light source device and the light valve.

4. The illuminating optical system of claim 3, wherein the polarization converter is formed of multiple sets of polarizing beam splitters with an associated half-wave plate for each set of polarizing beam splitters.

5. An illuminating optical system in combination with a projection lens system, said projection lens system including a light valve which is illuminated by the illuminating optical system, said illuminating optical system comprising:

a light source device having multiple light sources, each emitting a light beam centered about an optical axis of an associated light source;

an integrator section that is illuminated by the light source device, said integrator section including two lenticular lens arrays arranged along a light path, each said lenticular lens array having multiple lens regions which cause the light intensity distribution that is transmitted by the integrator section to be more uniform than the light incident on the integrator section from said light source device;

wherein

at least two of the multiple light sources are oriented so that the emitted light beams partially overlap at the surface of the lenticular lens array that is nearest the light source device, there also being regions of the lenticular lens array nearest the light source device which receive light from only a single light source, and

for the lenticular lens array nearest the light valve, an array element which receives light from an array element of the lenticular lens array nearest the light source device and which is illuminated by overlapping light beams is smaller in size than an array element that receives light from an array element of the lenticular lens array nearest the light source device and which is illuminated by a single light source.

6. The apparatus as set forth in claim 5, wherein the lenticular lens array of the integrator section that is farther from the light source device is smaller in overall area than the lenticular lens array of the integrator section that is nearer the light source device.