Optical: systems and elements – Single channel simultaneously to or from plural channels
Reexamination Certificate
1999-11-18
2001-10-30
Epps, Georgia (Department: 2873)
Optical: systems and elements
Single channel simultaneously to or from plural channels
C359S649000, C359S634000
Reexamination Certificate
active
06310726
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an image projecting device for projecting an image on a screen, and capable of shifting the image projected on the screen in a direction parallel to the screen.
As an example of such an image projecting device, in Japanese Patent Provisional Publication HEI 5-27324, an image projecting device employing a liquid crystal device is described. In the image projecting device described in the publication, parallel light is emitted by a light source and passes through a transmission type liquid crystal panel. The liquid crystal panel is driven to modulate the beam transmitting therein. The light beam passed through and modulated by the liquid crystal panel is projected on a screen via a condenser lens and an image projecting lens.
The condenser lens and the image projecting lens are mounted on a lens shift mechanism so as to be unitarily movable in a direction perpendicular to an optical axis of the image projecting lens. By shifting the condenser lens and the image projecting lens in the direction perpendicular to the optical axis, the image projected on the screen is shifted in the direction parallel to the screen without the keystone distortion.
Generally, various members of the image projecting device are accommodated in a casing, while the image projecting lens is arranged to be protruded from the casing. When the image projecting device is carried, such a protruded part may be inadvertently used in the manner of a handle, i.e., that the weight of the projector may be inappropriately supported on the protruding lens. If the projecting lens is made shiftable as described in the publication, when the protruded part of the image projecting lens is grasped and the image projecting device is lifted or carried to change a location of the image projecting device, undesirable force may be applied to the lens shifting mechanism and the mechanism may be broken.
Further, in the conventional structure of the image projecting device, a relatively large opening should be formed on the casing where the projecting lens is protruded in order to allow the projecting lens to move in the direction perpendicular to its optical axis. Therefore, a space is formed between the outer circumference of the projecting lens and the inner circumference of the opening, which deteriorates the appearance of the image projecting device.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an improved image projecting device. Even if the projecting lens protruded from the casing is grasped to lift the device, the lens shifting mechanism is not damaged. Further, the appearance is improved by eliminating space between the projecting lens and the inner circumferential of the opening through which the image projecting lens is protruded.
For the above object, according to the present invention, there is provided an image projecting device, which is provided with: a light source for emitting light; a modulating device that modulates the light emitted by the light source in accordance with an image to be projected; a projecting lens that receives the light emitted by the light source and modulated by the modulating device, and projects the modulated light on a screen; and a relay lens system provided between the modulating device and the projecting lens, the relay lens system being movable in at least one direction perpendicular to an optical axis of the projecting lens.
Since the image projected on the screen is shifted by shifting the relay lens which is located between the projecting lens and the modulating device, the projecting lens is not necessarily be moved, and can be fixed to a casing of the image projecting device. Therefore, even if the projecting lens is grasped by a user for lifting the device, the lens shifting mechanism is not damaged. Further, the appearance is improved since there is no space between the projecting lens and the inner circumferential of the opening through which the image projecting lens is protruded from the casing of the image projecting device.
Specifically, the relay lens is telecentric both on a modulating device side and on a projecting lens side, and the projection lens is telecentric on the relay lens side.
Optionally, the projection lens may be arranged such that an optical axis of the projection lens is shifted, with respect to a central axis of said modulating elements, in a direction perpendicular to the central axis of the modulating device. Alternatively, the projection lens may be arranged such that the optical axis of the projection lens coincides with a central axis of the modulating device.
The modulating device maybe configured to form a color image. For example, the modulating device may include: a plurality of transparent type liquid crystal panels capable of modulating different color components; a first set of dichroic mirrors provided between the light source and respective modulating elements, the dichroic mirrors limiting wavelength ranges of light entering the modulating elements, respectively; and another set of dichroic mirrors are provided between the relay lens and the modulating elements for combining light modulated by the modulating elements.
According to another aspect of the invention, there is provided an image projecting device, which is provided with: an image source that forms an image to be projected; a projecting lens that projects the image formed by the image source on a screen, the projecting lens being unmovable with respect to the image projecting device; and a relay lens system provided between the image source and the projecting lens, the relay lens system being movable in at least one direction perpendicular to an optical axis of the projecting lens.
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patent: 6183094 (2001-02-01), Ohta
patent: 5-27324 (1993-02-01), None
patent: 8-62566 (1996-03-01), None
Asahi Kogaku Kogyo Kabushiki Kaisha
Epps Georgia
Greenblum & Bernstein P.L.C.
Seyrafi Saeed
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