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US 7,215,477 B2Granted
Zoom lens and image display apparatus including the zoom lens
AssigneeCanon Kabushiki Kaisha
InventorsShinji Yamasaki, Takashi Sudo
Life of this patent
Estimating the term…
Abstract
Provided is a projection lens, including: a plurality of moving lens units that move on an optical axis for zooming; and a plurality of plastic lenses containing plastic, in which when a focal distance of an i-th positive lens from a predetermined plane side of N positive lenses of the plurality of plastic lenses is given by fpi, a focal distance of a j-th negative lens from the predetermined plane side of M negative lenses of the plurality of plastic lenses is given by fnj, and fp and fn are defined by 1 fp = ∑ i = 1 N 1 fpi 1 fn = ∑ j = 1 M 1 fnj (N and M each are a natural number, that is, an integer equal to or larger than 1), −0.56<fn/fp<−0.05 is satisfied.
Claims32
A projection lens comprising:
- a plurality of plastic lenses containing plastic,
- wherein when a focal distance of an i-th positive lens from a predetermined plane side of N positive lenses of the plurality of plastic lenses is given by fpi,
- a focal distance of a j-th negative lens from the predetermined plane side of M negative lenses of the plurality of plastic lenses is given by fnj, and
- fp and fn are defined by
- 1
- fp
- =
- ∑
- i
- =
- 1
- N
-
- 1
- fpi
- 1
- fn
- =
- ∑
- j
- =
- 1
- M
-
- 1
- fnj
- (N and M each are a natural number, that is, an integer equal to or larger than 1),
- −0.56<fn/fp<−0.05
- is satisfied,
- wherein 50% or more of a volume of each of the plastic lenses at 20 degrees centigrade is made of plastic.
27 more elements
A projection lens comprising:
- a plurality of plastic lenses containing plastic,
- wherein when a focal distance of an i-th positive lens from a predetermined plane side of N positive lenses of the plurality of plastic lenses is given by fpi,
- a focal distance of a j-th negative lens from the predetermined plane side of M negative lenses of the plurality of plastic lenses is given by fnj, and
- fp and fn are defined by
- 1
- fp
- =
- ∑
- i
- =
- 1
- N
-
- 1
- fpi
- 1
- fn
- =
- ∑
- j
- =
- 1
- M
-
- 1
- fnj
- (N and M each are a natural number, that is, an integer equal to or larger than 1),
- −0.56<fn/fp<−0.05
- is satisfied,
- wherein the projection lens comprises a first lens unit having negative refracting power, a second lens unit which is one of the plurality of moving lens units and has positive refracting power, a third lens unit which is one of the plurality of moving lens units and has positive refracting power, a fourth lens unit which is one of the plurality of moving lens units and has negative refracting power, a fifth lens unit which is one of the plurality of moving lens units and has positive refracting power, and a sixth lens unit having positive refracting power, which are disposed in order from a magnifying conjugate side (front) to a reducing conjugate side (rear), and
- wherein an interval between the first lens unit and the second lens unit, an interval between the second lens unit and the third lens unit, an interval between the third lens unit and the fourth lens unit, an interval between the fourth lens unit and the fifth lens unit, and an interval between the fifth lens unit and the sixth lens unit change in accordance with zooming, wherein the first lens unit and the sixth lens unit are not moved for zooming.
28 more elements
A projection lens comprising:
- a plurality of plastic lenses containing plastic,
- wherein when a focal distance of an i-th positive lens from a predetermined plane side of N positive lenses of the plurality of plastic lenses is given by fpi,
- a focal distance of a j-th negative lens from the predetermined plane side of M negative lenses of the plurality of plastic lenses is given by fnj, and
- fp and fn are defined by
- 1
- fp
- =
- ∑
- i
- =
- 1
- N
-
- 1
- fpi
- 1
- fn
- =
- ∑
- j
- =
- 1
- M
-
- 1
- fnj
- (N and M each are a natural number, that is, an integer equal to or larger than 1),
- −0.56<fn/fp<−0.05
- is satisfied,
- wherein the projection lens comprises a first lens unit having negative refracting power, a second lens unit which is one of the plurality of moving lens units and has positive refracting power, a third lens unit which is one of the plurality of moving lens units and has positive refracting power, a fourth lens unit which is one of the plurality of moving lens units and has positive refracting power, and a fifth lens unit having positive refracting power, which are disposed in order from a magnifying conjugate side (front) to a reducing conjugate side (rear), and
- wherein the first lens unit and the fifth lens unit are not moved for zooming.
28 more elements
A projection lens comprising:
- a plurality of plastic lenses containing plastic,
- wherein when a focal distance of an i-th positive lens from a predetermined plane side of N positive lenses of the plurality of plastic lenses is given by fpi,
- a focal distance of a j-th negative lens from the predetermined plane side of M negative lenses of the plurality of plastic lenses is given by fnj, and
- fp and fn are defined by
- 1
- fp
- =
- ∑
- i
- =
- 1
- N
-
- 1
- fpi
- 1
- fn
- =
- ∑
- j
- =
- 1
- M
-
- 1
- fnj
- (N and M each are a natural number, that is, an integer equal to or larger than 1),
- −0.56<fn/fp<−0.05
- is satisfied,
- wherein when a focal distance of an entire system of the projection lens in a zoom position at a wide angle end is given by fw,
- −7<fn/fw<−1
- is satisfied.
29 more elements
A projection lens comprising:
- a plurality of plastic lenses containing plastic,
- wherein when a focal distance of an i-th positive lens from a predetermined plane side of N positive lenses of the plurality of plastic lenses is given by fpi,
- a focal distance of a j-th negative lens from the predetermined plane side of M negative lenses of the plurality of plastic lenses is given by fnj, and
- fp and fn are defined by
- 1
- fp
- =
- ∑
- i
- =
- 1
- N
-
- 1
- fpi
- 1
- fn
- =
- ∑
- j
- =
- 1
- M
-
- 1
- fnj
- (N and M each are a natural number, that is, an integer equal to or larger than 1),
- −0.56<fn/fp<−0.05
- is satisfied,
- wherein
- a lens unit disposed closest to a magnifying conjugate side includes a plurality of lenses, each of which has negative refracting power, and
- of the plurality of lenses, a lens closest to a reducing conjugate side has a meniscus shape in which a surface of the lens on the reducing conjugate side is convex.
29 more elements
A projection lens comprising:
- a plurality of plastic lenses containing plastic,
- wherein when a focal distance of an i-th positive lens from a predetermined plane side of N positive lenses of the plurality of plastic lenses is given by fpi,
- a focal distance of a j-th negative lens from the predetermined plane side of M negative lenses of the plurality of plastic lenses is given by fnj, and
- fp and fn are defined by
- 1
- fp
- =
- ∑
- i
- =
- 1
- N
-
- 1
- fpi
- 1
- fn
- =
- ∑
- j
- =
- 1
- M
-
- 1
- fnj
- (N and M each are a natural number, that is, an integer equal to or larger than 1),
- −0.56<fn/fp<−0.05
- is satisfied,
- wherein when an average value of Abbe numbers of materials of negative lenses in a lens unit closest to a magnifying conjugate side is given by ν1n,
- 47<ν1n
- is satisfied.
29 more elements
A projection lens comprising:
- a plurality of plastic lenses containing plastic,
- wherein when a focal distance of an i-th positive lens from a predetermined plane side of N positive lenses of the plurality of plastic lenses is given by fpi,
- a focal distance of a j-th negative lens from the predetermined plane side of M negative lenses of the plurality of plastic lenses is given by fnj, and
- fp and fn are defined by
- 1
- fp
- =
- ∑
- i
- =
- 1
- N
-
- 1
- fpi
- 1
- fn
- =
- ∑
- j
- =
- 1
- M
-
- 1
- fnj
- (N and M each are a natural number, that is, an integer equal to or larger than 1),
- −0.56<fn/fp<−0.05
- is satisfied,
- wherein when a focal distance of the projection lens at a wide angle end is given by fw and an air conversion length of a back focus is given by bf,
- 0.25<fw/bf<0.60
- is satisfied.
29 more elements
An image display apparatus, comprising:
- a plurality of image display devices;
- an illumination optical system for illuminating the plurality of image display devices with light from a light source;
- a color composition system for synthesizing light beams from the plurality of image display devices;
- and
- a projection lens for projecting light from the color composition system onto the predetermined plane, said projection lens comprising:
- a plurality of plastic lenses containing plastic,
- wherein when a focal distance of an i-th positive lens from a predetermined plane side of N positive lenses of the plurality of plastic lenses is given by fpi,
- a focal distance of a j-th negative lens from the predetermined plane side of M negative lenses of the plurality of plastic lenses is given by fnj, and
- fp and fn are defined by
- 1
- fp
- =
- ∑
- i
- =
- 1
- N
-
- 1
- fpi
- 1
- fn
- =
- ∑
- j
- =
- 1
- M
-
- 1
- fnj
- (N and M each are a natural number, that is, an integer equal to or larger than 1),
- −0.56<fn/fp<−0.05
- is satisfied.
31 more elements
Dependencies are inferred from the claim text.