THREE DIMENSIONAL IMAGE PROJECTOR WITH CIRCULAR LIGHT POLARIZATION

• US 20130188151A1
• Filed: 11/09/2012
• Published: 07/25/2013
• Est. Priority Date: 01/25/2012
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: DeCusatis, Casimer M.
• Granted Patent: US 8,955,975 B2
• Time in Patent Office: Days
• US Class Current: 353/8
• CPC Class Codes: G02B 5/12 Reflex reflectors
• CPC Class Codes: G02B 6/27 with polarisation selective and adjusting means
• CPC Class Codes: G03B 21/2033 LED or laser light sources
• CPC Class Codes: G03B 21/2073 Polarisers in the lamp house peculiar to electronic spatial light modulators H04N9/3197
• CPC Class Codes: G03B 35/26 using polarised or coloured light separating different viewpoint images

Abstract

A method is provided that includes providing a light source having a light emitting diode (LED) that emits a light. A polarization conversion system (PCS) is located adjacent the LED and has both a linear polarizer and a wave plate. A polarizing beam splitter (PBS) is adjacent the light source and an imaging device is adjacent the PBS. The wave plate of the PCS is rotated to a first position, and a first light is emitted by the LED in the first light source. This first light is converted to circular polarization. This first light travels to the PBS where it is reflected onto the imaging device. The wave plate is then rotated to a second position, and a second light is emitted by the light source. This second light is converted to circular polarization and reflects from the PBS onto the imaging device.

Claims

1. A method comprising:

providing a light source having an light emitting diode (LED) that emits a light;

providing a polarization conversion system (PCS) adjacent the LED comprising a linear polarizer and a wave plate, the linear polarizer having an axis of polarization and the wave plate being rotatable between a first and second position;

providing a polarizing beam splitter (PBS) adjacent the light source;

providing an imaging device adjacent the PBS;

rotating the wave plate of the PCS to a first position;

emitting a first light from the light source;

converting the first light to circular polarization;

reflecting the first light with the PBS onto the imaging device;

rotating the wave plate of the PCS to a second position;

emitting a second light from the light source;

converting the second light to circular polarization; and

,

reflecting the second light with the PBS onto the imaging device.

2. The method of claim 1, further comprising:

providing a projection lens assembly adjacent the PBS opposite the imaging device;

emitting the first light reflected from the imaging device through the projection lens assembly; and

, emitting the second light reflected from the imaging device through the projection lens assembly.

3. The method according to claim 1 wherein the circular polarization of the first light is opposite the circular polarization of the second light.

4. The method of claim 1 wherein the wave plate is located in the first position when the wave plate forms a 45 degree angle with the axis of polarization of the linear polarizer.

5. The method of claim 1, wherein the wave plate is located in the second position when the wave plate forms a negative 45 degree angle with the axis of polarization of the linear polarizer.

6. The method of claim 1 wherein the imaging device is a liquid crystal on silicon (LCoS) device.

7. The method of claim 1 wherein the light source additionally comprises a conic section reflector on which the LED is mounted.