OPTICAL HEAD-MOUNTED DISPLAY WITH MECHANICAL ONE-DIMENSIONAL SCANNER

• US 20140226193A1
• Filed: 04/21/2014
• Published: 08/14/2014
• Est. Priority Date: 10/25/2011
• Status: Active Grant

• Current Assignee: National Central University
• Original Assignee: National Central University
• Inventors: SUN, CHING-CHERNG
• Granted Patent: US 8,934,160 B2
• Time in Patent Office: Days
• US Class Current: 359/19
• CPC Class Codes: G02B 26/10 Scanning systems
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 5/32 Holograms used as optical elements

Abstract

An optical head-mounted display includes an eyeglass frame, a holographic optical element supported by the eyeglass frame to be confronted by an eye of a wearer, and a projector mounted on the eyeglass frame to project image information on the holographic optical element. The projector includes a LED light source, a beam-splitting polarizer, a spatial light modulator, a lens set and a mechanical one-dimensional scanner. The mechanical one-dimensional scanner reflects the transformed light beam from the lens set onto the holographic optical element in one dimension at a time. When the reflective sheet is rotated at a range of angle in a brief moment of time, the holographic optical element receives from the rotating reflective sheet an array of one-dimensional modulated light beams and reflects the latter to form a two-dimensional image in the eye because of persistence of vision.

Claims

1. An optical head-mounted display comprising an eyeglass frame, a holographic optical element (HOE) supported by the eyeglass frame to be confronted by an eye of a wearer, and a projector mounted on the eyeglass frame to project image information on the holographic optical element, wherein the projector includes:

a LED light source;

a beam-splitting polarizer configured to split an incident beam from the LED light source into two light beams of differing linear polarization;

a spatial light modulator for modulating an associated one of the two light beams from the beam-splitting polarizer;

a lens set for transforming the modulated light beam from the spatial light modulator;

a mechanical one-dimensional scanner comprising a pivotable reflective sheet for reflecting the transformed light beam from the lens set onto the holographic optical element in one dimension at a time, and a controller for controlling rotation of the reflective sheet about an axis step by step; and

the holographic optical element having properties of wavelength selectivity and angle selectivity and allowing light to pass through;

wherein when the reflective sheet is rotated about the axis at a range of angle in a brief moment of time, the holographic optical element gradually receives from the rotating reflective sheet an array of one-dimensional transformed light beams and reflects the latter to form a two-dimensional image in the eye of the wearer because of persistence of vision.

2. The optical head-mounted display as claimed in claim 1, wherein the light source is a white LED light source including one blue LED, one red LED and one green LED.

3. The optical head-mounted display as claimed in claim 1, wherein the light source is a phosphor-based white LED.

4. The optical head-mounted display as claimed in claim 1, further comprising a light guide interposed between the light source and the beam-splitting polarizer to direct light generated by the light source to the beam-splitting polarizer.

5. The optical head-mounted display as claimed in claim 1, further comprising a diffuser interposed between the light source and the beam-splitting polarizer to diffusing light generated by the light source.

6. The optical head-mounted display as claimed in claim 1, wherein the spatial light modulator is a Liquid Crystal on Silicon-Spatial Light Modulator (LCOS-SLM).

7. The optical head-mounted display as claimed in claim 1, wherein the projector is disposed on an upper edge of the eyeglass frame.

8. The optical head-mounted display as claimed in claim 7, further comprising at least one eyeglass lens, wherein the holographic optical element is disposed on a front side of the eyeglass lens away from the eye of the wearer.