# US 10,768,429 B2 · Image display device

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- Number: US 10,768,429 B2
- Document ID: US10768429B2
- Status: Granted
- Kind: B2
- Application number: 16/230,976
- Filed: 2018-12-21
- Published: 2019-09-12
- Granted: 2020-09-08
- Earliest claimed: 2018-03-12
- Assignees: JVCKENWOOD Corporation
- Applicants: JVC KENWOOD Corporation
- Inventors: Fumihiko Ito
- Web page: https://patentgrep.com/patent/US10768429B2

## CPC

- G02B 27/0172: {characterised by optical features}
- G02B 5/30: Polarising elements (light-modulating devices with active elements G02F1/00)
- G02B 3/08: with discontinuous faces, e.g. Fresnel lens {(diffractive Fresnel lenses G02B5/1876)}
- G02B 27/283: {used for beam splitting or combining}
- G02B 2027/011: {comprising device for correcting geometrical aberrations, distortion}
- G02B 2027/0123: {comprising devices increasing the field of view}
- G02B 2027/013: {comprising a combiner of particular shape, e.g. curvature}
- G02B 2027/0134: {of stereoscopic type}
- G02B 2027/0136: {with a single image source for both eyes}
- G02B 2027/0145: {creating an intermediate image}
- G02B 2027/0152: {involving arrangement aiming to get lighter or better balanced devices}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A relay lens system forms an image displayed on an image display unit as an intermediate image. A luminous flux of the image emitted from the relay lens system reflected by a half mirror is incident to a curved combiner, and the combiner reflects the incident luminous flux to the half mirror to enable an observer to observe a virtual image through the half mirror. The relay lens system forms the intermediate image at an intermediate image forming position on an optical axis before a light reflected by the half mirror is incident to the curved combiner. The distance from the optical axis of the curved combiner to a light emission surface of the relay lens system is shorter than or equal to the distance from the optical axis of the curved combiner to a maximum reflection position.

## Claims

### Claim 1

An image display device comprising:
an image display unit;
a relay lens system configured to form an image displayed on the image display unit as an intermediate image;
a reflection/transmission unit configured to reflect a portion of an incident light and to transmit the rest of the incident light; and
a curved mirror, to which a luminous flux of the image emitted from the relay lens system and reflected by the reflection/transmission unit is incident from the reflection/transmission unit, configured to reflect the luminous flux incident thereto to the reflection/transmission unit and to enable an observer to observe a virtual image of the image through the reflection/transmission unit,
wherein:
the relay lens system forms the intermediate image, on an optical axis, at a position between a position where the light is reflected by the reflection/transmission unit and a position where the light reflected by the reflection/transmission unit is incident to the curved mirror, and
in a cross section passing through an optical axis of the curved mirror and perpendicular to a horizontal direction of a field of view of the observer, a distance from the optical axis of the curved mirror to a light emission surface of the relay lens system is shorter than or equal to a distance from the optical axis of the curved mirror to a maximum reflection position indicating a position where a luminous flux emitted from an end of the image display unit is reflected at the curved mirror.

### Claim 2 (depends on 1)

The image display device according to claim 1, wherein when a focal length of the curved mirror is f, and a width of the intermediate image in the horizontal direction of the field of view of the observer is x, a value of x/f is 0.58 or more and 1.19 or less.

### Claim 3 (depends on 1)

The image display device according to claim 1, wherein a magnification of the relay lens system is set to a range of 0.4 times or more and 59.6 times or less.

### Claim 4 (depends on 1)

The image display device according to claim 1, wherein the relay lens system, the reflection/transmission unit, and the curved mirror are coaxial optical systems sharing an optical axis with each other.

### Claim 5 (depends on 1)

The image display device according to claim 1, wherein the curved mirror is a curved combiner which combines an incident light from external environment and a reflected light of a light incident from the reflection/transmission unit.

### Claim 6 (depends on 1)

The image display device according to claim 1, wherein the reflection/transmission unit includes a half mirror which transmits a portion of a light and reflects at least a portion of the light not transmitted.

### Claim 7 (depends on 1)

The image display device according to claim 1, wherein the reflection/transmission unit includes a polarization beam splitter which reflects a light with a predetermined polarization plane and transmits a light with a polarization plane perpendicular to the predetermined polarization plane, and a ¼ wavelength plate arranged between the curved mirror and the polarization beam splitter.

### Claim 8 (depends on 1)

The image display device according to claim 1, wherein the relay lens system includes a concave lens and a convex lens.