Image projection system

• US 6,520,643 B1
• Filed: 01/11/2002
• Issued: 02/18/2003
• Est. Priority Date: 09/30/1996
• Status: Expired due to Term

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Digital Optics International Corporation
• Inventors: Cox, Arthur, Holman, Robert L.
• Primary Examiner(s): DOWLING, WILLIAM C
• Application Number:
  US10/043,840
• Time in Patent Office: 403 Days
• Field of Search: 353/7, 353/8, 353/20, 353/31, 349/8, 349/9, 359/464, 359/465, 359/472, 359/497, 359/501, 359/494, 359/495
• US Class Current: 353/20
• CPC Class Codes: G03B 21/2073 Polarisers in the lamp house peculiar to electronic spatial light modulators H04N9/3197
• CPC Class Codes: G03B 21/208 Homogenising, shaping of the illumination light
• CPC Class Codes: G03B 21/62 Translucent screens

Abstract

An image projection system for generating an image on a projection screen using a highly compact geometry. The optical system uses polarized light manipulated by at least one of a conicoid, or plane optical elements to effect a folded mirror system to project an image onto the screen.

Claims

1. An imaging system, comprising:

an output screen;

means for generating light;

a light source system for projecting an image on said output screen with polarized light such that a first portion of light of a first polarization state from the means for generating light is output for imaging without change of polarization state and a second portion of light of a second polarization state is converted to polarized light of the first polarization state for display on said screen and said light source system including;

(a) a lens for projecting an enlarged image onto said screen;

(b) a first set of polarization selective light reflecting elements, including a first reflecting element which passes image light of a first polarization state and reflects the image light of a second polarization state, a second element which converts the image light of the second polarization state into the image light of a first circular polarization state such that the image light of the first circular polarization state is transmitted by said first set of reflecting elements and output for viewing on said screen and the image light of the first circular polarization state is further processed; and

(c) a second set of polarization selective partially curved light reflecting elements which are at least one of curved and tilted and including a second reflecting element which reflects the image light of the first circular polarization state while converting it to a second circular polarization state, the second circular polarization state being orthogonal to the first circular polarization state, the image light is converted to the first polarization state by passage through the first polarization converting element, and thereby passes through the first reflecting element further projecting the image light onto said screen.

2. An illuminating system, comprising:

an output screen;

means for generating light;

a light source system for illuminating said output screen with polarized light such that a first portion of light of a first polarization state from the means for generating light is output for illuminating without change of polarization state and a second portion of light of a second polarization state is converted to polarized light of the first polarization state for illuminating said output screen, said light source system including;

(a) a first polarization selective light processing element including a conicoidal light processing element whose vertex contains a small inlet that receives light from the means for generating light and the small inlet passes light of mixed polarization state output from at least one light emitting diode and the conicoidal light processing element converts the light incident on a surface of the conicoidal light processing element from a first circular polarization state into reflected light of a second circular polarization state, the second circular polarization state being orthogonal to that of said first circular polarization state;

(b) a second polarization selective light processing element including a first element which reflects light of a second linear polarization state and also transmits light of a first linear polarization state and further including a second optical element for converting light of the second linear polarization state into light of second circular polarization state and upon reflecting from said conicoidal light processing element becomes light of said first linear polarization state, thereby enabling output through the first light processing element of light of the first linear polarization state onto the output screen; and

said output screen including at least one of a Fresnel lens, a micro lens, a polarization converter and a diffuser for converting the light of the first linear polarization state passed through said Fresnel lens into at least one output beam of specific angular extent to at least one of an LCD display screen, a human observer and a designated area for general illumination from said illuminating system.

3. The illuminating system as defined in claim 2 wherein the at least one light emitting diode is disposed within said inlet in said vertex of said conicoidal light processing element.

4. The illuminating system as defined in claim 2 wherein the at least one light emitting diode is disposed below said inlet in said vertex of said conicoidal light processing element.

5. The illuminating system as defined in claim 3 wherein said light emitting diode emits a color selected from the group of monocolor, white, red, green, blue and mixtures thereof.

6. The illuminating system as defined in claim 2 wherein said output screen and the first and second polarization light processing elements have aperture areas with shape selected from the group of square and rectangular.

7. The illuminating system as defined in claim 4 wherein said first polarization selective light processing element contains at least one of a one dimensional and a two dimensional array of contiguous ones of the conicoidal light processing elements, each said conicoidal light processing element having a vertex containing a small inlet passing light of mixed polarization state emanating from the light emitting diode disposed at least one of in said inlet and below said inlet.

8. The illuminating system as defined in claim 7 wherein the area of said square or rectangular aperture area shape falls within a range of 25 mm² to 2500 mm².

9. The illuminating system as defined in claim 2 further including an array of the conicoidol light processing element, thereby enabling borderless image formation on all sides of the output screen.