Projection device with a folded optical path and wire-grid polarizer
First Claim
1. A projection display device for displaying an image, comprising:
- a) a screen having a front defined by where the image is viewed and a rear;
b) a mirror opposing the rear of the screen and oriented at an acute angle with respect to the screen;
c) a retarder disposed between the screen and the mirror;
d) a wire-grid polarizer substantially contiguous with the screen and having an array of parallel conductive nano-wires with a period less than 200 nm; and
e) an image projection engine oriented to direct a polarized image beam containing an image towards the wire-grid polarizer with the image beam having a linear polarization and an optical axis; and
f) the polarized image beam of the linear polarization propagating in a plane oriented;
i) to contain a nano-wire of the array and ii) with an incidence angle with respect to the array greater than 45 degrees and iii) not within a plane of incidence with respect to the array.
1 Assignment
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Accused Products
Abstract
A folded projection display system includes a wire-grid polarizer placed immediately behind the system'"'"'s imaging screen. The display system includes an image projector that projects an image beam containing light of a predetermined linear polarization toward the imaging screen. The wire-grid polarizer reflects the light in the image beam away from the screen. The reflected image beam then encounters a ¼-wavelength achromatic retarder that converts the linear polarization to circular polarization. The image beam next hits a mirror that reflects the light back through the ¼-wavelength achromatic retarder, which converts the circular polarization back to linear polarization, with the polarization director rotated 90 degrees from the original polarization direction. The wire-grid polarizer then allows the light to pass through to the image screen.
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Citations
15 Claims
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1. A projection display device for displaying an image, comprising:
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a) a screen having a front defined by where the image is viewed and a rear; b) a mirror opposing the rear of the screen and oriented at an acute angle with respect to the screen; c) a retarder disposed between the screen and the mirror; d) a wire-grid polarizer substantially contiguous with the screen and having an array of parallel conductive nano-wires with a period less than 200 nm; and e) an image projection engine oriented to direct a polarized image beam containing an image towards the wire-grid polarizer with the image beam having a linear polarization and an optical axis; and f) the polarized image beam of the linear polarization propagating in a plane oriented;
i) to contain a nano-wire of the array and ii) with an incidence angle with respect to the array greater than 45 degrees and iii) not within a plane of incidence with respect to the array. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A projection display device for displaying an image, comprising:
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a) a screen having a front defined by where the image is viewed and a rear; b) a mirror opposing the rear of the screen and oriented at an acute angle with respect to the screen; c) a retarder disposed between the screen and the mirror; d) a wire-grid polarizer substantially contiguous with the screen and having an array of parallel conductive nano-wires with a period less than 200 nm; and e) an image projection engine oriented to direct a polarized image beam containing an image towards the wire-grid polarizer with the image beam having a linear polarization and an optical axis; and f) the polarized image beam of the linear polarization propagating in a plane oriented i) to contain a nano-wire of the array and ii) with an incidence angle with respect to the array greater than 45 degrees and iii) not within an angle of incidence with respect to the array; and g) the orientation of the image projection engine with respect to the wire-grid polarizer having a reflection of the image beam of at least 85% during a first encounter and a transmission of the image beam of at least 85% during a second encounter.
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Specification