# US 7,611,246 B2 · Projection display and optical integrator

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- Number: US 7,611,246 B2
- Document ID: US7611246B2
- Status: Granted
- Kind: B2
- Application number: 11/480,388
- Filed: 2006-07-05
- Published: 2007-01-11
- Granted: 2009-11-03
- Earliest claimed: 2005-07-05
- Assignees: Hitachi, Ltd.
- Inventors: Nobuyuki Kimura; Kentaro Kato
- Web page: https://patentgrep.com/patent/US7611246B2

## CPC

- G02B 27/285: {comprising arrays of elements, e.g. microprisms}
- G03B 21/208: {Homogenising, shaping of the illumination light}
- G03B 27/54: Lamp housings; Illuminating means
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- 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)

## Abstract

A projection display makes it possible to minimize the costs of a polarization conversion element, and concurrently makes it possible to improve illuminance nonuniformity and optical utilization efficiency and to accomplish physical apparatus compactness. An optical integrator used in the projection display is configured such that, in comparison to the number of arrangements of polarization conversion units in a predetermined direction, a split number of an array lens in the same direction is greater.

## Claims

### Claim 1

A projection display, comprising:
a light source;
an image display element that forms an optical image by using light emitted by the light source;
a projection lens that performs magnified projection of the optical image;
a polarization conversion element that emanates light which is incident on the image display element, as polarized light and that includes a plurality of units arranged in an even number of rows along a first direction to be symmetric with respect to a center axis;
a first array lens including a plurality of first lens cells that are arranged along a direction substantially parallel to the polarization conversion element and that are arranged in the first direction in an odd number of rows which is greater than the number of rows of the plurality of units; and
a second array lens including a plurality of second lens cells that are arranged in the first direction in an odd number of rows respectively in correspondence to the first lens cells of the first array lens,
wherein a width of a second lens cell of a center row in the first direction is narrower than widths of second lens cells of other rows.

### Claim 2 (depends on 1)

A projection display according to claim 1, wherein, in the first array lens, first lens cells arranged on two sides of the center row in the first direction, respectively, have curvature center axes symmetric with one another with respect to an axis corresponding to the curvature center axis of the first lens cell arranged in the center row.

### Claim 3 (depends on 1)

A projection display according to claim 1, wherein, in the second array lens, second lens cells arranged on two sides of the center row in the first direction, respectively, have curvature center axes that are symmetric with one another with respect to an axis corresponding to the curvature center axis of the second lens cell arranged in the center row.

### Claim 4 (depends on 1)

A projection display according to claim 1, wherein
light rays passing through the center row in the first direction and the second lens cells on two sides of the center row pass through two units of the plurality of units, the two units being respectively arranged in two columns sandwiching the center axis.

### Claim 5 (depends on 1)

A projection display according to claim 1, wherein:
the plurality of units are arranged in a plurality of columns symmetric with respect to the center axis in the first direction;
the plurality of first lens cells are arranged in the first direction in an odd number of columns which is greater than the number of columns of the plurality of units; and
the plurality of second lens cells are arranged in the first direction in an odd number of columns respectively in correspondence to the first lens cells of the first array lens.

### Claim 6 (depends on 1)

A projection display according to claim 1, wherein a relationship of
Wm≦2/3Wp
is satisfied, where Wm is a width of the second lens cell in the center row in the first direction, and Wp is a width of an opening portion of the polarization conversion element.

### Claim 7

An optical integrator usable in a projection display, comprising:
a first array lens including a plurality of first lens cells arranged in a first direction in an odd number of rows; and
a second array lens including a plurality of second lens cells that are arranged in the first direction in an odd number of rows respectively in correspondence to the first lens cells of the first array lens, wherein a width of a second lens cell of a center row in the first direction is narrower than widths of second lens cells of other rows;
wherein the plurality of first lens cells are arranged in the first direction in an odd number of columns; and
wherein the plurality of second lens cells are arranged in the first direction in an odd number of columns, wherein a width of a second lens cell in a center column in the first direction is narrower than widths of other second lens cells.

### Claim 8

A projection display, comprising:
a light source;
an image display element that forms an optical image by using light emitted by the light source;
a projection lens that performs magnified projection of the optical image;
a polarization conversion element that emanates light which is incident on the image display element, as polarized light and that includes a plurality of units arranged in an n columns (n =positive integer) along a first direction;
a first array lens including a plurality of first lens cells that are arranged along a direction substantially parallel to the polarization conversion element and that are arranged in the first direction in at least an n+1 rows; and
a second array lens including a plurality of second lens cells that are arranged in the first direction in at least n1 columns respectively in correspondence to the first lens cells of the first array lens, wherein light rays emanated from, a plurality of certain second lens cells adjacent to one another, of the second lens cells, are incident on one of the plurality of units.

### Claim 9 (depends on 8)

A projection display according to claim 8, wherein:
the polarization conversion element includes the plurality of units arranged line-symmetric in an even number of rows along the first direction;
the second array lens includes second lens cells arranged in an odd number along the first direction; and
the plurality of certain second lens cells adjacent to one another are second lens cells arranged in three central columns along the first direction, and light rays passing through the second lens cells arranged in the three central columns are incident on a plurality of units arranged in two central columns in the polarization conversion element.

### Claim 10 (depends on 8)

A projection display according to claim 8, wherein:
the plurality of units are arranged in a plurality of columns symmetric with respect to the center axis in the first direction;
the plurality of first lens cells are arranged in the first direction in an odd number of columns which is greater than the number of columns of the plurality of units; and
the plurality of second lens cells are arranged in the first direction in an odd number of columns respectively in correspondence to the first lens cells of the first array lens.

### Claim 11 (depends on 1)

A projection display according to claim 1, wherein a relationship of
Wm≦2/3Wp
is satisfied, where Wm is a width of the second lens cell in the center row in the first direction, and Wp is a width of an opening portion of the polarization conversion element.