# US 9,519,205 B2 · Projection image display device

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

- Number: US 9,519,205 B2
- Document ID: US9519205B2
- Status: Granted
- Kind: B2
- Application number: 14/654,852
- Filed: 2013-03-29
- Published: 2016-03-24
- Granted: 2016-12-13
- Earliest claimed: 2013-03-29
- Assignees: Hitachi Maxell, Ltd.
- Applicants: Hitachi Maxell, Ltd.
- Inventors: Koji Hirata
- Web page: https://patentgrep.com/patent/US9519205B2

## CPC

- G03B 21/208: {Homogenising, shaping of the illumination light}
- G02B 6/0093: {Means for protecting the light guide}
- G02B 7/02: for lenses {(supports for magnifying lenses G02B25/002)}
- G02B 13/0095: {Relay lenses or rod lenses (in instruments for viewing the inside of hollow bodies G02B23/2446)}
- G02B 13/16: for use in conjunction with image converters or intensifiers {, or for use with projectors, e.g. objectives for projection TV}
- G02F 1/1336: {Illuminating devices}
- G03B 21/006: {using LCD's}
- H04N 5/7441: {the modulator being an array of liquid crystal cells}
- G03B 21/2026: {Gas discharge type light sources, e.g. arcs}
- 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
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

A projection image display device includes a rod lens of rectangular cross section, into which white light from a light source enters, and exits as diffused light of uniform illumination intensity. The rod lens is provided with: only a single pair of rods which are formed by splitting the rod lens along the optical axis so as to bifurcate it along long sides of the rectangular cross section, and which have a thin filmed formed on a portion at the periphery of the mutually opposed surfaces thereof; and with a cover part that covers the outside periphery of the pair of rods, for retaining the pair of rods in such a way that the rods are opposed a slight distance apart due to the thin film formed on the mutually opposed surfaces, and that has openings formed at the light entry side and the light exit side of the rod lens.

## Claims

### Claim 1

A projection-type image display device comprising:
a light source configured to radiate white light;
a rod lens with a square cross section configured to receive the white light from the light source enter, and to output light with uniformly dispersed illuminance;
an optical modulation element arranged near an outgoing surface of the rod lens, and configured to modulate the light output from the rod lens as incoming light according to an image signal to form a display image; and
a projecting lens configured to enlarge and project the display image modulated in the optical modulation element, wherein
the rod lens includes
only a pair of rods formed divided along an optical axis to divide the rod lens into equal two parts with long sides of the square cross section of the rod lens, and having a thin film formed on a part of a periphery of mutually facing surfaces, and
a cover unit that covers an external periphery of the pair of rods, holds the pair of rods to face each other, slightly separated with the thin film formed on the mutually facing surfaces, and forms openings in an incoming side and an outgoing side of the rod lens,
wherein the cover unit includes an external wall that covers the external periphery of the pair of rods, and a plurality of holding frame parts protruding from an inner surface of the external wall in a frame manner, and abutting on the external periphery of the pair of rods, and an opening in the incoming side of the cover unit is formed in a square manner such that the thin film formed on the facing surface of the pair of rods is positioned outside the opening when the rod lens is viewed from a side of the opening.

### Claim 2 (depends on 1)

The projection-type image display device according to claim 1, wherein the thin film formed on the mutually facing surfaces of the only pair of rods that configures the rod lens is formed on a corner part of the facing surface of one of the only pair of rods.

### Claim 3 (depends on 2)

The projection-type image display device according to claim 2, wherein the thin film is formed of an Si thin film or a metal thin film.