# US 12,114,106 B2 · Light-source device and image forming apparatus including same

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 12,114,106 B2
- Document ID: US12114106B2
- Status: Granted
- Kind: B2
- Application number: 18/139,959
- Filed: 2023-04-27
- Published: 2024-03-07
- Granted: 2024-10-08
- Earliest claimed: 2019-11-01
- Assignees: Ricoh Company, Ltd.
- Applicants: Ricoh Company, Ltd.
- Inventors: Yohei Takano; Kazuhiro Fujita; Kasumi Nakamura
- Web page: https://patentgrep.com/patent/US12114106B2

## CPC

- 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 9/3158: {for controlling the spectrum}
- G02B 27/0977: {Reflective elements}
- G02B 27/1006: {for splitting or combining different wavelengths (G02B27/1086, G02B27/141 take precedence)}
- G02B 27/18: for optical projection, e.g. combination of mirror and condenser and objective {(photographic, cine and overhead projectors G03B21/00; photographic projection printing G03B27/32; photolithographic projectors G03F7/20; projection television H04N5/74; colour projection television H04N9/31)}
- G03B 21/2013: {Plural light sources}
- G03B 21/2033: {LED or laser light sources}
- G03B 21/2066: {Reflectors in illumination beam (in projection beam G03B21/28)}
- G03B 21/208: {Homogenising, shaping of the illumination light}
- G03B 33/08: Sequential recording or projection (G03B33/02, G03B33/04, G03B33/06 take precedence)
- H04N 9/3152: {for shaping the light beam (beam shaping per se G02B27/09)}
- H04N 9/3164: {using multiple light sources}
- 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)
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A light-source device includes an excitation light source, an optical member, and a wavelength converter. The excitation light source is configured to emit first color light. The optical member has a reflecting surface configured to reflect the first color light emitted from the excitation light source. The wavelength converter includes a wavelength conversion member on which the first color light reflected by the optical member is incident. The wavelength conversion member is configured to convert at least part of the first color light into second color light having a wavelength different from a wavelength of the first color light and emit the second color light. A center of the first color light on the reflecting surface of the optical member does not intersect with a light flux of the first color light emitted from the wavelength converter.

## Claims

### Claim 1

A light-source device, comprising:
an excitation light source configured to emit first color light;
an optical element having a reflecting surface configured to reflect the first color light emitted from the excitation light source; and
a wavelength converter including a wavelength conversion member on which the first color light reflected by the optical element is incident, the wavelength conversion member being configured to convert at least part of the first color light into second color light having a wavelength different from a wavelength of the first color light and emit the second color light,
wherein a center of the first color light on the reflecting surface of the optical element does not intersect with a light flux of the first color light emitted from the wavelength converter,
the light-source device further comprising:
a first optical system;
a second optical system having a positive power, the first optical system and the second optical system being disposed in an order of the first optical system and the second optical system from a side of the excitation light source on an optical path between the excitation light source and the wavelength converter; and
a refractive optical system and a light mixing element that are disposed on an optical path of the first color light reflected by the wavelength converter and the second color light emitted from the wavelength converter,
wherein a light flux of the first color light is emitted from the refractive optical system and is incident at an angle with respect to an incident-side surface of the light mixing element along a short direction of the light mixing element, and
wherein a shape of the incident-side surface of the light mixing element is rectangular.

### Claim 2 (depends on 1)

The light-source device according to claim 1, wherein:
the light mixing element includes four reflecting surfaces, and
50% or more of rays of the first color light are first incident on a reflecting surface having a larger area than another reflecting surface among the four reflecting surfaces.

### Claim 3 (depends on 2)

The light-source device according to claim 2,
wherein the first optical system is configured to emit excitation light as a condensed light flux.

### Claim 4 (depends on 2)

The light-source device according to claim 2,
wherein a light condensing point of excitation light reflected by the wavelength converter is between the second optical system and the refractive optical system.

### Claim 5 (depends on 4)

The light-source device according to claim 4,
wherein said optical element is disposed closer to the light condensing point than each of the second optical system and the refractive optical system is.

### Claim 6 (depends on 4)

The light-source device according to claim 4,
wherein a position of the light condensing point is behind one of the reflecting surfaces or a virtual plane including said one of the reflecting surfaces in a traveling direction of a light flux.

### Claim 7 (depends on 4)

The light-source device according to claim 4,
wherein another light condensing point of excitation light reflected by the optical element is between the wavelength converter and a surface of an incident side of the second optical system.

### Claim 8 (depends on 2)

The light-source device according to claim 2,
wherein a relation of 0.1<D1/D2<0.6 is satisfied,
where D1 is an outer diameter of an optical element on an emission side of the first optical system and D2 is an outer diameter of an optical element on an incident side of the second optical system.

### Claim 9 (depends on 8)

The light-source device according to claim 8,
wherein the first optical system is configured to emit excitation light as a condensed light flux.

### Claim 10 (depends on 8)

The light-source device according to claim 8,
wherein a light condensing point of excitation light reflected by the wavelength converter is between the second optical system and the refractive optical system.

### Claim 11 (depends on 8)

The light-source device according to claim 8,
wherein a light flux of the first color light is emitted from the refractive optical system as divergent light and is incident at an angle with respect to an incident-side surface of the light mixing element along the short direction of the light mixing element.

### Claim 12 (depends on 8)

An image projection apparatus, comprising:
the light-source device according to claim 8;
an image display element configured to generate an image;
an illumination optical system configured to guide light emitted from the light-source device to the image display element; and
a projection optical system configured to project an image generated by the image display element, with the light guided by the illumination optical system.

### Claim 13 (depends on 2)

The light-source device according to claim 2,
wherein a relation of 6<L int/SE<12 is satisfied,
where L int is a length of the light mixing element and SE is a length of an aperture of the light mixing element in the short direction of the light mixing element.

### Claim 14 (depends on 13)

The light-source device according to claim 13,
wherein the first optical system is configured to emit excitation light as a condensed light flux.

### Claim 15 (depends on 13)

The light-source device according to claim 13,
wherein a light condensing point of excitation light reflected by the wavelength converter is between the second optical system and the refractive optical system.

### Claim 16 (depends on 13)

An image projection apparatus, comprising:
the light-source device according to claim 13;
an image display element configured to generate an image;
an illumination optical system configured to guide light emitted from the light-source device to the image display element; and
a projection optical system configured to project an image generated by the image display element, with the light guided by the illumination optical system.

### Claim 17 (depends on 1)

The light-source device according to claim 1,
wherein the excitation light source includes a light source unit, the light source unit including:
a plurality of laser diodes arranged in rows and columns; and
a plurality of coupling lenses on emission surface sides of the laser diodes, respectively, and
wherein an arrangement interval of the laser diodes satisfies a relation of 1≤p/L tan θ≤4,
where θ is a larger one of a divergence angle in a row direction and a divergence angle in a column direction of the first color light emitted from the laser diodes, p is a pitch of adjacent ones of the laser diodes, and L is a distance from a light emission point of each of the laser diodes to a corresponding one of the coupling lenses.

### Claim 18 (depends on 1)

An image projection apparatus, comprising:
the light-source device according to claim 1;
an image display element configured to generate an image;
an illumination optical system configured to guide light emitted from the light-source device to the image display element; and
a projection optical system configured to project an image generated by the image display element, with the light guided by the illumination optical system.

### Claim 19 (depends on 1)

The light-source device according to claim 1, wherein:
the first color light emitted from the second optical system is incident on the refractive optical system on one side with respect to an optical axis of the refractive optical system, and passes through the refractive optical system on the one side with respect to the optical axis of the refractive optical system.