Oblique projection optical system and method for setting the same
AssigneeMinolta Co., Ltd.
InventorJun Ishihara
Life of this patent
Estimating the term…
Abstract
An oblique projection optical system is compact as compared with the size of the image it presents, offers high imaging performance, produces satisfactorily small distortion, and has a small f-number. The oblique projection optical system is composed of a plurality of powered reflection surfaces, of which the one closest to the projection surface is positively powered and the one second closest thereto is negatively powered. At least one of these two reflection surfaces is a free-form surface, and the one closest to the projection surface has a size larger than half the size of the projection surface.
Claims13
A projection optical system that directs rays of light from a display surface to a projection surface in such a way that a ray of light from a center of the display surface is obliquely incident on the projection surface in order to form on the projection surface an optical image of an image displayed on the display surface, the projection optical system comprising:
- a plurality of reflection surfaces for successively reflecting the rays of light from the display surface to direct the rays of light to the projection surface,
- wherein, when relative positions of the plurality of reflection surfaces with respect to the projection surface are expressed based on order in which the reflection surfaces reflect the rays of light,
- of the plurality of reflection surfaces, the reflection surface closest to the projection surface is a free-form surface, has a size larger than half a size of the projection surface in both of directions corresponding to height and width directions of the display surface, and has a positive optical power.
A projection optical system that directs rays of light from a display surface to a projection surface in such a way that a ray of light from a center of the display surface is obliquely incident on the projection surface in order to form on the projection surface an optical image of an image displayed on the display surface, the projection optical system comprising:
- a plurality of reflection surfaces, each having an optical power, for successively reflecting the rays of light from the display surface to direct the rays of light to the projection surface,
- wherein, when relative positions of the plurality of reflection surfaces with respect to the projection surface are expressed based on order in which the reflection surfaces reflect the rays of light,
- of the plurality of reflection surfaces, the reflection surface closest to the projection surface has a positive optical power and has a size larger than half a size of the projection surface in both of directions corresponding to height and width directions of the display surface,
- of the plurality of reflection surfaces, the reflection surface second closest to the projection surface has a negative optical power, and
- at least one of the reflection surfaces closest and second closest to the projection surface is a free-form surface.
A projection optical system that directs rays of light from a display surface to a projection surface in such a way that a ray of light from a center of the display surface is obliquely incident on the projection surface in order to form on the projection surface an optical image of an image displayed on the display surface, the projection optical system comprising:
- a plurality of reflection surfaces, each having an optical power, for successively reflecting the rays of light from the display surface to direct the rays of light to the projection surface,
- wherein, when relative positions of the plurality of reflection surfaces with respect to the projection surface are expressed based on order in which the reflection surfaces reflect the rays of light,
- of the plurality of reflection surfaces, the reflection surface closest to the projection surface has a positive optical power and has a size larger than half a size of the projection surface in both of directions corresponding to height and width directions of the display surface,
- of the plurality of reflection surfaces, the reflection surface second closest to the projection surface has a negative optical power,
- of the plurality of reflection surfaces, the reflection surface third closest to the projection surface has a positive optical power, and
- at least two of the reflection surfaces closest, second closest, and third closest to the projection surface are free-form surfaces.
Dependencies are inferred from the claim text.