Image projection system with a polarizing beam splitter
DCFirst Claim
1. An image projection system for providing a bright and clear image, the system comprising:
- a light source producing a visible light beam;
a polarizing beam splitter located near the light source in the light beam and oriented at an angle with respect to the light beam, the beam splitter comprising a transparent substrate having a first surface located in the light beam with the light beam striking the first surface at an angle, and a generally parallel arrangement of thin, elongated elements supported by the substrate, the arrangement being configured and the elements being sized to interact with electromagnetic waves of the source light beam to generally (i) transmit light through the elements which has a polarization oriented perpendicular to a plane that includes at least one of the elements and the direction of the incident light beam, defining a transmitted beam, and (ii) reflect light from the elements which has a polarization oriented parallel with the plane that includes at least one of the elements and the direction of the incident light beam, defining a reflected beam;
a reflective array located near the polarizing beam splitter in either the reflected or transmitted beam, the array modulating the polarization of the beam by selectively altering the polarization of the beam to encode image information thereon and creating a modulated beam, the array being oriented to direct the modulated beam back towards the polarizing beam splitter;
the beam splitter further being located in the modulated beam and oriented at an angle with respect to the modulated beam, and the arrangement of elements of the beam splitter interacting with electromagnetic waves of the modulated beam to generally (i) transmit light through the elements which has a polarization oriented perpendicular to the plane that includes at least one of the elements and the direction of the incident light beam, defining a second transmitted beam, and (ii) reflect light from the elements which has a polarization parallel with the plane that includes at least one of the elements and the direction of the incident light beam, defining a second reflected beam, to separate out the unaltered polarization from the modulated beam;
a screen located in either the second reflected beam or the second transmitted beam for displaying the encoded image information.
1 Assignment
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Accused Products
Abstract
An image projection system has a wire grid polarizing beam splitter which functions as both the polarizer and the analyzer in the system. A light source produces a source light beam directed at the beam splitter which reflects one polarization and transmits the other. A liquid crystal array is disposed in either the reflected or transmitted beam. The array modulates the polarization of the beam, encoding image information thereon, and directs the modulated beam back to the beam splitter. The beam splitter again reflects one polarization and transmits the other so that the encoded image is either reflected or transmitted to a screen. The wire grid polarizing beam splitter is capable of being oriented at various incident angles with respect to the source light beam and modulated beam, and accepts relatively divergent light.
229 Citations
32 Claims
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1. An image projection system for providing a bright and clear image, the system comprising:
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a light source producing a visible light beam;
a polarizing beam splitter located near the light source in the light beam and oriented at an angle with respect to the light beam, the beam splitter comprising a transparent substrate having a first surface located in the light beam with the light beam striking the first surface at an angle, and a generally parallel arrangement of thin, elongated elements supported by the substrate, the arrangement being configured and the elements being sized to interact with electromagnetic waves of the source light beam to generally (i) transmit light through the elements which has a polarization oriented perpendicular to a plane that includes at least one of the elements and the direction of the incident light beam, defining a transmitted beam, and (ii) reflect light from the elements which has a polarization oriented parallel with the plane that includes at least one of the elements and the direction of the incident light beam, defining a reflected beam;
a reflective array located near the polarizing beam splitter in either the reflected or transmitted beam, the array modulating the polarization of the beam by selectively altering the polarization of the beam to encode image information thereon and creating a modulated beam, the array being oriented to direct the modulated beam back towards the polarizing beam splitter;
the beam splitter further being located in the modulated beam and oriented at an angle with respect to the modulated beam, and the arrangement of elements of the beam splitter interacting with electromagnetic waves of the modulated beam to generally (i) transmit light through the elements which has a polarization oriented perpendicular to the plane that includes at least one of the elements and the direction of the incident light beam, defining a second transmitted beam, and (ii) reflect light from the elements which has a polarization parallel with the plane that includes at least one of the elements and the direction of the incident light beam, defining a second reflected beam, to separate out the unaltered polarization from the modulated beam;
a screen located in either the second reflected beam or the second transmitted beam for displaying the encoded image information. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
wherein the arrangement of elements has a period less than approximately 0.21 microns, wherein the elements have a thickness between approximately 0.04 to 0.5 microns, and wherein the elements have a width of between approximately 30 to 76% of the period. -
15. The system of claim 1, wherein the elements each have a cross section with a base, a top opposite the base, and opposite left and right sides;
- and wherein the sides form an angle with respect to the base greater than approximately 68 degrees.
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16. An image projection system comprising:
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a light source producing a visible light beam having a wavelength between approximately 0.4 and 0.7 microns;
a polarizing beam splitter located near the light source in the light beam and oriented at an angle with respect to the light beam, the beam splitter comprising a transparent substrate having a surface located in the light beam with the light beam striking the surface at an angle, and a generally parallel arrangement of thin, elongated elements supported by the substrate, the arrangement being configured and the elements being sized to interact with electromagnetic waves of the source light beam to generally (i) transmit light through the elements which has a polarization oriented perpendicular to a plane that includes at least one of the elements and the direction of the incident light beam, defining a transmitted beam, and (ii) reflect light from the elements which has a polarization oriented parallel with the plane that includes at least one of the elements and the direction of the incident light beam, defining a reflected beam;
a reflective array located near the polarizing beam splitter in the reflected beam, the array modulating the polarization of the reflected beam by selectively altering the polarization of the reflected beam to encode image information thereon and creating a modulated beam, the array being oriented to direct the modulated beam back to the polarizing beam splitter;
the polarizing beam splitter further being located in the modulated beam and oriented at an angle relative to the modulated beam, the arrangement of elements of the beam splitter interacting with electromagnetic waves of the modulated beam to generally (i) transmit light through the elements which has a polarization oriented perpendicular to a plane that includes at least one of the elements and the direction of the incident light beam, defining a transmitted beam, and (ii) reflect light from the elements which has a polarization parallel with the plane that includes at least one of the elements and the direction of the incident light beam, to separate out the unaltered polarization from the modulated beam; and
a screen disposed in the transmitted beam for displaying the encoded image information. - View Dependent Claims (17, 18, 19, 20, 21)
wherein the arrangement of elements has a period less than approximately 0.21 microns, wherein the elements have a thickness between approximately 0.04 to 0.5 microns, and wherein the elements have a width of between approximately 30 to 76% of the period.
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22. An image projection system comprising:
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a light source producing a visible light beam having a wavelength between approximately 0.4 and 0.7 microns;
a polarizing beam splitter located near the light source in the light beam and oriented at an angle with respect to the light beam, the beam splitter comprising a transparent substrate having a surface located in the light beam with the light striking the surface at an angle, and a generally parallel arrangement of thin, elongated elements supported by the substrate, the arrangement being configured and the elements being sized to interact with electromagnetic waves of the source light beam to generally (i) transmit light through the elements which has a polarization oriented perpendicular to the plane that includes at least one of the elements and the direction of the incident light beam, defining a transmitted beam, and (ii) reflect light from the elements which has a polarization oriented parallel with the plane that includes at least one of the elements and the direction of the incident light beam;
a reflective array located near the polarizing beam splitter in the transmitted beam, the array modulating the polarization of the transmitted beam by selectively altering the polarization of the transmitted beam to encode image information thereon and creating a modulated beam, and being oriented to direct the modulated beam back to the beam splitter;
the polarizing beam splitter further being located in the modulated beam and oriented at an angle with respect to the modulated beam, the arrangement of elements of the beam splitter interacting with electromagnetic waves of the modulated beam to generally (i) transmit light through the elements which has a polarization oriented perpendicular to a plane that includes at least one of the elements and the direction of the incident light beam, and (ii) reflect light from the elements which has a polarization parallel with the plane that includes at least one of the elements and the direction of the incident light beam, defining a reflected beam, to separate the altered polarization from the unaltered polarization in the modulated beam, thereby extracting the image information in the modulated beam; and
a screen located in the reflected beam for displaying the extracted image information in the modulated beam. - View Dependent Claims (23, 24, 25, 26, 27)
wherein the arrangement of elements has a period less than approximately 0.21 microns, wherein the elements have a thickness between approximately 0.04 to 0.5 microns, and wherein the elements have a width of between approximately 30 to 76% of the period.
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28. A method for projecting an image, the method comprising:
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producing a source light beam having a wavelength in a range between approximately 0.4 to 0.7 microns using a light source;
substantially separating the polarizations of the source light beam using a polarizing beam splitter disposed in the source light beam, the polarizing beam splitter comprising a generally parallel arrangement of thin, elongated elements configured and sized to interact with electromagnetic waves of the source light beam to generally (i) transmit light through the elements which has a polarization oriented perpendicular to a plane that includes at least one of the elements and the direction of the incident light beam, defining a transmitted beam, and (ii) reflect light from the elements which has a polarization orientation that lies in the plane that includes at least one of the elements and the direction of the incident light beam, defining a reflected beam;
modulating either the transmitted or reflected beam and creating a modulated beam by selectively altering the polarization of the beam using an array disposed in either the transmitted or reflected beam;
substantially separating the polarizations of the modulated beam using the polarizing beam splitter disposed in the modulated beam, the elements interacting with electromagnetic waves of the modulated beam to generally (i) transmit light through the elements which has a polarization oriented perpendicular to plane that includes at least one of the elements and the direction of the incident light beam, defining a second transmitted beam, and (ii) reflect light from the elements which has a polarization orientation that lies in the plane that includes at least one of the elements and the direction of the incident light beam, defining a second reflected beam; and
displaying either the second transmitted beam or the second reflected beam on a screen.
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29. An image display system for producing a visible image, the system comprising:
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a light source for emitting a source light beam having a wavelength in a range between approximately 0.4 to 0.7 microns;
a liquid crystal array positioned and oriented for receiving and modulating at least a portion of the source light beam and creating a modulated beam, the modulated beam containing image information;
a screen positioned and oriented for receiving and displaying at least a portion of the modulated beam; and
a polarizing beam splitter disposed in both the source light beam and the modulated beam, the beam splitter being used at an F-number less than approximately f/2.5, the polarizing beam splitter comprising a generally parallel arrangement of thin, elongated elements configured and sized to interact with electromagnetic waves of the source light beam to generally (i) transmit light through the elements which has a polarization oriented perpendicular to a plane that includes at least one of the elements and the direction of the incident light beam, defining a transmitted beam, and (ii) reflect light from the elements which has a polarization orientation that lies in the plane that includes at least one of the elements and the direction of the incident light beam, defining a reflected beam, and interacts with the electromagnetic waves of the modulated beam to generally (i) transmit light through the elements which has a polarization oriented perpendicular to a plane that includes at least one of the elements and the direction of the modulated light beam, defining a second transmitted beam, and (ii) reflect light from the elements which has a polarization orientation that lies in the plane that includes at least one of the elements and the direction of the modulated light beam, defining a second reflected beam; and
wherein the beam splitter is oriented with respect to the source light beam at an angle of incidence between approximately 10 to 80 degrees. - View Dependent Claims (30, 31, 32)
wherein the arrangement of elements has a period less than approximately 0.21 microns, wherein the elements have a thickness between approximately 0.04 to 0.5 microns, and wherein the elements have a width of between approximately 30 to 76% of the period. -
31. The system of claim 29, wherein the array is disposed in the reflected beam, and wherein the screen is disposed in the second transmitted beam.
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32. The system of claim 29, wherein the array is disposed in the transmitted beam, and wherein the screen is disposed in the second reflected beam.
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Specification