Variable magnification projection optical system and projection apparatus
AssigneeKonica Minolta, Inc.
InventorAtsuo MASUI
Life of this patent
Estimating the term…
Abstract
A variable magnification projection optical system includes, in order from an enlargement side: a first lens group having negative refractive power; a second lens group having negative refractive power; and a third lens group having positive refractive power. During zooming, the first lens group is fixed, and the second lens group and the third lens group move. The second lens group includes a plurality of lenses each having positive refractive power. All lenses each having positive refractive power in the first lens group and the second lens group are made of a glass material having a transmittance greater than 0.98 per thickness of 10 mm with respect to light having a wavelength of 440 nm.
Claims17
A variable magnification projection optical system that enlarges and projects an image displayed on an image display surface, the variable magnification projection optical system comprising, in order from an enlargement side:
- a first lens group having negative refractive power,
- a second lens group having negative refractive power;
- and
- a third lens group having positive refractive power, wherein
- during zooming, the first lens group is fixed, and the second lens group and the third lens group move,
- the second lens group includes a plurality of lenses each having positive refractive power, and
- all lenses each having positive refractive power in the first lens group and the second lens group are made of a glass material having a transmittance greater than 0.98 per thickness of 10 mm with respect to light having a wavelength of 440 nm.
A variable magnification projection optical system that enlarges and projects an image displayed on an image display surface, the variable magnification projection optical system comprising, in order from an enlargement side:
- a first lens group having negative refractive power,
- a second lens group having negative refractive power;
- and
- a third lens group having positive refractive power, wherein
- during zooming, the first lens group is fixed, and the second lens group and the third lens group move,
- the second lens group includes a plurality of lenses each having positive refractive power, and
- a refractive index of each of all lenses that has positive refractive power in the first lens group and the second lens group with respect to a d-line is smaller than 1.6.
Dependencies are inferred from the claim text.