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US 6,285,509 B1Granted
Zoom lens and display apparatus having the same
AssigneeCanon Kabushiki Kaisha
InventorsHiroki Nakayama, Akihiro Nishio, Saburo Sugawara
Life of this patent
Estimating the term…
Abstract
A zoom lens for projecting an original image onto a screen in an enlarged scale includes, in order from the screen side, a first lens unit of negative refractive power, a second lens unit of positive refractive power, a third lens unit of negative refractive power, a fourth lens unit of positive refractive power and a fifth lens unit of positive refractive power, wherein, during zooming from a wide-angle end to a telephoto end, the second lens unit and the fourth lens unit move toward the screen side.
Claims47
A zoom lens comprising in order from a larger conjugate side,
- a first lens unit of negative refractive power,
- a second lens unit of positive refractive power which moves toward the larger conjugate side during zooming from a wide-angle end to a telephoto end,
- a third lens unit of negative refractive power,
- a fourth lens unit of positive refractive power which moves toward the larger conjugate side during zooming from the wide-angle end to the telephoto end,
- a fifth lens unit of positive refractive power, and
- a stop which moves during zooming from the wide-angle end to the telephoto end,
- wherein the lens satisfies the following condition:
- |tk|/fw>4.0
- where fw is a focal length of a whole lens system at the wide angle end, and tk is a minimum value of a distance from a conjugate surface on a smaller conjugate side to a pupil on the smaller conjugate side during zooming from the wide-angle end to the telephoto end.
6 more elements
A zoom lens, comprising in order from a larger conjugate side,
- a first lens unit of negative refractive power,
- a second lens unit of positive refractive power which moves toward a larger conjugate side during zooming from a wide-angle end to a telephoto end, and
- a third lens unit of negative refractive power,
- wherein the zoom lens satisfies the following conditions:
- |tk|/fw>4.0
- ν1n>60
- wherein fw is a focal length of a whole lens system at the wide-angle end, and tk is a minimum value of a distance from a conjugate surface on a smaller conjugate side to a pupil on the smaller conjugate side during zooming from the wide-angle end to the telephoto end, and
- ν1n is a mean value of Abbe numbers of negative lenses of the first lens unit.
5 more elements
A display apparatus, comprising:
- display means for displaying an image, and
- a zoom lens for projecting the image onto a projection surface,
- wherein the zoom lens comprising in order from a larger conjugate side:
- a first lens unit of negative refractive power,
- a second lens unit of positive refractive power which moves toward the larger conjugate side during zooming from a wide-angle end to a telephoto end,
- a third lens unit of negative refractive power,
- a fourth lens unit which moves toward the larger conjugate side during the zooming from the wide-angle end to the telephoto end, and
- a fifth lens unit of positive refractive power.
5 more elements
A zoom lens, comprising in order from a larger conjugate side,
- a first lens unit of negative refractive power, having at least one aspherical surface,
- a second lens unit of positive refractive power, which moves toward the larger conjugate side during zooming from a wide-angle end to a telephoto end,
- a third lens unit of negative refractive power,
- a fourth lens unit of positive refractive power, which moves toward the larger conjugate side during the zooming from the wide-angle end of the telephoto end, and
- a fifth lens unit of positive refractive power,
- wherein the zoom lens satisfies the following condition:
- 4<|tkw/fw|
- where tkw is a distance from a pupil on the larger conjugate side at the wide-angle end to a conjugate surface on a smaller conjugate side at the wide-angle end when the conjugate length on the larger conjugate side is infinite, and fw is a focal length of a whole zoom lens system at the wide-angle end.
5 more elements
A zoom lens comprising, in order from a larger conjugate side:
- a first lens unit of negative refractive power,
- a second lens unit of positive refractive power, which moves toward the larger conjugate side during zooming from a wide-angle end to a telephoto end,
- a third lens unit of negative refractive power,
- a fourth lens unit of positive refractive power, which moves toward the larger conjugate side during the zooming from the wide-angle end of the telephoto end,
- a fifth lens unit of positive refractive power, and
- at least one aspherical surface,
- wherein the zoom lens satisfies the following condition:
- 4<|tkw/fw|
- where tkw is a distance from a pupil on the larger conjugate side at the wide-angle end to a conjugate surface on a smaller conjugate side at the wide-angle end when the conjugate length on the larger conjugate side is infinite and fw is a focal length of a whole zoom lens system at the wide-angle end.
6 more elements
A zoom lens, comprising in order from a larger conjugate side,
- a first lens unit of negative refractive power,
- a second lens unit of positive refractive power, which moves toward the larger conjugate side during zooming from a wide-angle end to a telephoto end,
- a third lens unit of negative refractive power,
- a fourth lens unit of positive refractive power, which moves toward the larger conjugate side during the zooming from the wide-angle end to the telephoto end, and
- a fifth lens unit of positive refractive power, and
- a stop which moves together with the second lens unit during the zooming from the wide-angle end to the telephoto end.
3 more elements
Dependencies are inferred from the claim text.