Video display device and head-mounted display

Patent metadata

Field	Value
Publication number	US-9835865-B2
Application number	US-201414777712-A
Country	US
Kind code	B2
Filing date	Mar 11, 2014
Priority date	Mar 26, 2013
Publication date	Dec 5, 2017
Grant date	Dec 5, 2017

Abstract

A video display device includes: a display element displaying images by modulating light from an illumination optical system; and an eyepiece optical system guiding image light from the display element into an optical pupil. The illumination optical system includes: a light source including light emission points arranged substantially linearly; a diffuser plate diffusing illumination light from the light source in a first direction, in which the light emission points are arranged, but not in a second direction perpendicular to the first direction; and an optical element bending the illumination light such that the optical pupil and the light source are substantially conjugate. The optical element includes an illumination mirror, a reflection surface thereof having a non-zero curvature in all sections including a normal line at the optical-axis intersection. Here, the section perpendicular to the first direction has a different curvature from the section perpendicular to the second direction.

First claim

The invention claimed is:

1. A video display device comprising:
an illumination optical system;
a display configured to display an image by modulating light from the illumination optical system; and
an eyepiece optical system configured to guide image light from the display to an optical pupil,
wherein the illumination optical system includes
a light source including a plurality of light emission points which are arranged substantially on a straight line,
a diffuser plate configured to diffuse illumination light from the light source in a first direction in which the plurality of light emission points are arranged but not to diffuse the illumination light from the light source in a second direction which is perpendicular to the first direction, and
an optical mirror configured to bend the illumination light such that, in an optical system from the optical pupil to the light source including the eyepiece optical system, the optical pupil and the light source are substantially conjugate with each other with respect to the second direction,

wherein the optical mirror includes an illumination mirror, a reflection surface of which has a curvature that is not zero in each of sections including a normal line at a point of intersection of the reflection surface with an optical axis such that, of the sections, a section perpendicular to the first direction and a section perpendicular to the second direction have different curvatures, the optical axis being an axis optically connecting a center of the optical pupil to a center of a display surface of the display along with any extension line of the axis,
wherein the reflection surface of the illumination mirror has a shape whose sections perpendicular to the first direction all have a same curvature and are shifted from each other in the direction of the normal line according to positions thereof in the first direction, and
wherein an amount of normal-line-direction shift of the sections perpendicular to the first direction is set such that principal rays at all angles of view in the first direction intersect each other substantially at one point when the principal rays at the all angles of view in the first direction are reversely traced from the center of the optical pupil toward the light source, neglecting diffusion performed by the diffuser plate.

2. The video display device according to claim 1 ,
wherein the curvature of the reflection surface of the illumination mirror is maximum in the section perpendicular to the first direction and minimum in the section perpendicular to the second direction.

3. The video display device according to claim 1 ,
wherein the eyepiece optical system includes an eyepiece prism configured to guide the image light from the display inside the eyepiece prism.

4. The video display device according to claim 3 , further comprising:
a first polarizing element configured to polarize the illumination light from the illumination optical system; and
a second polarizing element configured to reflect the illumination light from the first polarizing element toward the display, and to transmit the image light from the display,
wherein the display is a reflective liquid crystal display.

5. The video display device according to claim 4 ,
wherein the second polarizing element is attached to a light incidence surface of the eyepiece prism.

6. A head-mounted display comprising:
the video display device according to claim 1 ; and
a support member that supports the video display device in front of an observer's eye.

7. The video display device according to claim 6 ,
wherein the eyepiece optical system includes a hologram optical mirror configured to diffract and reflect the image light guided inside the eyepiece optical mirror, and the hologram optical mirror has a curvature only in the first direction.

8. A head-mounted display comprising:
the video display device according to claim 5 ; and
a support member that supports the video display device in front of an observer's eye.

Assignees

• Konica Minolta Inc

Inventors

• Inagaki Yoshihiro

Classifications

• G02B27/0176

  characterised by mechanical features · CPC title

• G02B5/3025

  Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state (G02B5/3008, G02B5/3016 take precedence) · CPC title

• G02B27/0018

  with means for preventing ghost images (anti-reflection coatings G02B1/11) · CPC title

• G02B2027/0174

  holographic · CPC title

• G02B2027/0118

  comprising devices for improving the contrast of the display / brillance control visibility · CPC title