# US 9,039,187 B2 · Illumination optical system and a projector using the same

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- Number: US 9,039,187 B2
- Document ID: US9039187B2
- Status: Granted
- Kind: B2
- Application number: 13/642,833
- Filed: 2010-05-21
- Published: 2013-02-14
- Granted: 2015-05-26
- Earliest claimed: 2010-05-21
- Assignees: NEC Display Solutions, Ltd.
- Applicants: Atsushi Katou
- Inventors: Atsushi Katou
- Web page: https://patentgrep.com/patent/US9039187B2

## CPC

- G03B 21/14: Details
- G02B 5/26: Reflecting filters (G02B5/28 takes precedence)
- G03B 21/204: {using secondary light emission, e.g. luminescence or fluorescence (using different colours G03B33/00; if related to video signals H04N9/3197)}
- H04N 9/3114: {by using a sequential colour filter producing one colour at a time}
- H04N 9/3161: {using laser light sources (using laser beams scanning the display screen H04N9/3129)}
- G02B 2207/113: Fluorescence
- G03B: APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR (optical parts of such apparatus G02B; photosensitive materials or processes for photographic purposes G03C; apparatus for processing exposed photographic materials G03D)
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

The present invention seeks to realize a small etendu illumination optical system, a longer operating life and a higher brightness. The illumination optical system comprises: a laser light source that generates an excitation light; a fluorescent substance that generates a fluorescent light in response to the excitation light, a light tunnel that outputs the excitation light input at one end thereof to the fluorescent substance from the other end thereof, and that outputs the fluorescent light generated by the fluorescent substance from the one end thereof; and a mirror that is placed within a light path between the laser light source and the light tunnel, and that reflects the fluorescent light, the mirror having an aperture formed thereon that allows the excitation light to pass through.

## Claims

### Claim 1

An illumination optical system comprising: a laser light source that generates an excitation light; a fluorescent substance that generates a fluorescent light in response to the excitation light; a light tunnel that outputs the excitation light input at one end thereof to said fluorescent substance from the other end thereof, and that outputs the fluorescent light generated by said fluorescent substance from the one end thereof; and a mirror that is placed within a light path between said laser light source and said light tunnel, and that reflects the fluorescent light, said mirror having an aperture formed thereon that allows the excitation light to pass through, the fluorescent light being reflected by a part of the mirror which is different than the aperture; wherein the part of the mirror which is different from the aperture prevents the excitation light from passing therethrough.

### Claim 2 (depends on 1)

The illumination optical system according to claim 1, wherein said fluorescent substance comprises a fluorescent wheel that has a plurality of fluorescent areas that generate fluorescent lights with differing wavelengths, said fluorescent wheel being rotated whereby the position on said fluorescent wheel that is irradiated by said light tunnel moves on the respective fluorescent areas.

### Claim 3 (depends on 1)

An illumination optical system comprising a plurality of units, each constituted by said illumination optical system according to claim 1, wherein said fluorescent substance in each unit generates a fluorescent light with a differing wavelength, and wherein each unit further comprises a cross dichroic prism that inputs the output light from the unit and outputs the output light in the same direction.

### Claim 4 (depends on 1)

The illumination optical system according to claim 1 further comprising a second light source that emits an excitation light towards said fluorescent substance from the side of fluorescent substance opposite to said light tunnel,
wherein said fluorescent substance comprises a reflective layer that is located at the side of said second light source, allows the excitation light to pass through, but reflects the fluorescent light; and a fluorescent substance layer that is located at the side of said light tunnel.

### Claim 5 (depends on 1)

A projector having the illumination optical system according claim 1.

### Claim 6 (depends on 1)

The illumination optical system according to claim 1, wherein the excitation light passes through the mirror only at the aperture of the mirror.

### Claim 7 (depends on 1)

The illumination optical system according to claim 1, wherein the excitation light passes through the aperture of the mirror such that the excitation light is not incident on the mirror.

### Claim 8 (depends on 1)

The illumination optical system according to claim 1, wherein the excitation light passes through the mirror only at the aperture of the mirror, and
wherein the excitation light passes through the aperture of the mirror such that the excitation light does not hit the mirror.