Variable magnification optical system and projector
First Claim
1. A variable magnification optical system comprising:
- a reflective optical element having a positive magnification power and configured to be movable relative to an object plane; and
a refractive optical system configured to form an intermediate image between the object plane and the reflective optical element, the refractive optical system including plural refractive optical elements, wherein a substantially constant magnification of the intermediate image to the object plane is maintained before and after the magnification change applied to an image projected onto a screen by moving at least one of the plural refractive optical elements;
increasing a distance between the screen and the reflective optical element increases a magnification applied to the image projected onto the screen, and a change in distance between the screen and the reflective optical element, to effect a change in magnification applied to an image projected onto the screen, is substantially the same as a corresponding change in distance between the reflective optical element and the object plane.
1 Assignment
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Accused Products
Abstract
A variable magnification optical system projects an image onto a screen with a sufficient magnification without requiring a large-sized mirror. The variable magnification optical system includes a first optical system through which a light beam modulated with an image signal corresponding to the image is passed; a second optical system disposed downstream of the first optical system in a direction of travel of the light beam along an optical axis; and a reflective optical element having a magnification power that is configured to reflect the light beam from the second optical system toward the screen. A magnification of the image projected on the screen is changed by moving the reflective optical element relative to the object plane, thus changing a distance between the screen and the reflective optical element, while an incident angle of the light beam on the screen is maintained substantially constant.
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Citations
20 Claims
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1. A variable magnification optical system comprising:
- a reflective optical element having a positive magnification power and configured to be movable relative to an object plane; and
a refractive optical system configured to form an intermediate image between the object plane and the reflective optical element, the refractive optical system including plural refractive optical elements, wherein a substantially constant magnification of the intermediate image to the object plane is maintained before and after the magnification change applied to an image projected onto a screen by moving at least one of the plural refractive optical elements;
increasing a distance between the screen and the reflective optical element increases a magnification applied to the image projected onto the screen, and a change in distance between the screen and the reflective optical element, to effect a change in magnification applied to an image projected onto the screen, is substantially the same as a corresponding change in distance between the reflective optical element and the object plane. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
- a reflective optical element having a positive magnification power and configured to be movable relative to an object plane; and
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16. A variable magnification optical system for projecting an image onto a screen, the system comprising:
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a first optical system through which a light beam irradiated from an object plane is passed; a second optical system disposed downstream of the first optical system in a direction of travel of the light beam along an optical axis; and a reflective optical element having a magnification power that is configured to reflect the light beam from the second optical system toward the screen, wherein a magnification of the image projected on the screen is changed by moving the reflective optical element relative to the object plane, thus changing a distance between the screen and the reflective optical element, while an incident angle of the light beam on the screen is maintained substantially constant, and a change in distance between the screen and the reflective optical element, to effect a change in magnification applied to an image projected onto the screen, is substantially the same as a corresponding change in distance between the reflective optical element and the object plane. - View Dependent Claims (17, 18)
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19. A variable magnification optical apparatus comprising:
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a light source; an image generation unit that receives light from the light source; a reflective optical element having a positive magnification power and configured to be movable relative to an object plane of the image generation unit; and a refractive optical system configured to form an intermediate image between the object plane and the reflective optical element, the refractive optical system including plural refractive optical elements, wherein a movement of the reflective optical element effects a magnification change applied to an image projected onto a screen, a substantially constant magnification of the intermediate image to the object plane is maintained before and after the magnification change applied to the image projected onto the screen by moving at least one of the plural refractive optical elements, and when magnifying the image projected onto the screen, the distance between the screen and the reflective optical element is enlarged without changing the distance between the screen and the object plane.
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20. A variable magnification optical apparatus for projecting an image onto a screen, the apparatus comprising:
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a light source; an image generation unit that receives light from the light source; a first optical system through which a light beam irradiated from an object plane of the image generation unit is passed; a second optical system disposed downstream of the first optical system in a direction of travel of the light beam along an optical axis; and a reflective optical element having a magnification power that is configured to reflect the light beam from the second optical system toward the screen, wherein a magnification of the image projected on the screen is changed by moving the reflective optical element relative to the object plane, thus changing a distance between the screen and the reflective optical element, while an incident angle of the light beam on the screen is maintained substantially constant, and when magnifying the image projected onto the screen, the distance between the screen and the reflective optical element is enlarged without changing the distance between the screen and the object plane.
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Specification