IMAGE DISPLAY DEVICE USING VARIABLE-FOCUS LENS AT CONJUGATE IMAGE PLANE

• US 20100289970A1
• Filed: 07/27/2010
• Published: 11/18/2010
• Est. Priority Date: 01/29/2008
• Status: Active Grant

• Current Assignee: Brother Kogyo Kabushiki Kaisha (Brother Industries Limited)
• Original Assignee: Brother Kogyo Kabushiki Kaisha (Brother Industries Limited)
• Inventors: WATANABE, Mitsuyoshi
• Granted Patent: US 8,262,234 B2
• Time in Patent Office: Days
• US Class Current: 348/745
• CPC Class Codes: G02B 15/00 Optical objectives with means for varying the magnification anamorphotic objectives G02B13/08
• CPC Class Codes: G02B 2027/0127 comprising devices increasing the depth of field
• CPC Class Codes: G02B 27/017 Head mounted
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 3/12 Fluid-filled or evacuated lenses

Abstract

An image display device for optically displaying an image is disclosed. This device includes: a light source; an imaging-light generator converting light emitted from the light source, into imaging light representative of the image to be displayed, to thereby generate the imaging light; a relay optical system focusing the imaging light emitted from the imaging-light generator, on an image plane which is located at an optically conjugate position to the imaging-light generator, the relay optical system defining a pupil through which the imaging light passes, within the relay optical system; a variable-focus lens disposed at a position generally coincident with the pupil, the variable-focus lens having a varying focal length; and a wavefront-curvature adjuster configured to vary the focal length by operating the variable-focus lens, to thereby adjust a wavefront curvature of the imaging light emitted from the relay optical system.

Claims

1. An image display device for optically displaying an image, comprising:

a light source;

an imaging-light generator converting light emitted from the light source, into imaging light representative of the image to be displayed, to thereby generate the imaging light;

a relay optical system focusing the imaging light emitted from the imaging-light generator, on an image plane which is located at an optically conjugate position to the imaging-light generator, the relay optical system defining a pupil through which the imaging light passes, within the relay optical system;

a variable-focus lens disposed at a position generally coincident with the pupil, the variable-focus lens having a varying focal length; and

a wavefront-curvature adjuster configured to vary the focal length by operating the variable-focus lens, to thereby adjust a wavefront curvature of the imaging light emitted from the relay optical system.

2. The image display device according to claim 1, wherein the wavefront-curvature adjuster includes a modulator modulating the wavefront curvature based on depth information of the image.

3. The image display device according to claim 1, wherein the image is made up of a series of successive frames,

the imaging-light generator includes a generating section configured to generate the imaging light, on a per-frame basis, so that a plurality of pixels representing each frame are displayed at a time, and

the wavefront-curvature adjuster includes an adjusting section configured to adjust the wavefront curvature, on a per-frame basis, in synchronization with display of the successive frames.

4. The image display device according to claim 1, wherein the image is made up of a collection of a plurality of pixels, and

the wavefront-curvature adjuster includes an adjusting section configured to adjust the wavefront curvature, on a per-pixel basis or a per-pixel-group basis.

5. The image display device according to claim 1, wherein the image the image is made up of a series of successive frames,

each frame is made up of a collection of a plurality of pixels,

the imaging-light generator includes a generating section configured to generate the imaging light, on a per-frame basis, so that the plurality of pixels representing each frame are displayed in a time-division sequence, on a per-pixel basis or a per-pixel-group basis, and

the wavefront-curvature adjuster includes an adjusting section configured to adjust the wavefront curvature, on a per-pixel basis or a per-pixel-group basis, in synchronization with display of the successive pixels or pixels groups.

6. The image display device according to claim 1, wherein the variable-focus lens includes at least one of a liquid-crystal lens, a liquid lens, and a movable lens which is movable along an optical axis of the relay optical system.

7. The image display device according to claim 1, wherein the imaging-light generator includes at least one of an optical scanner, and a flat panel display.

8. The image display device according to claim 7, wherein the imaging-light generator includes the flat panel display, and the flat-panel display includes at least one of a liquid-crystal display, an organic electroluminescence display, and a digital micro-mirror device.

9. The image display device according to claim 1, further comprising:

an eyepiece optical system disposed downstream of the relay optical system, and

a wavefront-curvature offset mechanism configured to move the eyepiece optical system along an optical axis of the eyepiece optical system, and holding the eyepiece optical system at an arbitrarily-selected position, to thereby offset the wavefront curvature from a default value.

10. The image display device according to claim 1, further comprising a calibrator configured to move the variable-focus lens along an optical axis of the relay optical system, and holding the variable-focus lens at an arbitrarily-selected position, to thereby calibrate a location of the variable-focus lens relative to the relay optical system.