Patent US4702567A successfully refreshed from Google Patents.
US4702567A
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US
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Zoom lens
Assignee: Canon Inc
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Filing: 1987-02-18
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Granted: 1987-10-27
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Expires: 2007-02-18
Abstract
Abstract A zoom lens having a component V which has at least one group of lens elements axially movable mainly for changing image magnification, a component C which has at least one group of lens elements axially movable for compensating for the image shift resulting from the change of image magnification to maintain the constant position of the image plane, and a compound component F positioned on the image side of either, or both, of said component V and said component C to be movable with zooming, and having a plurality of lens groups contributing to a small overall refractive power, whereby the focusing provision is made in at least one of the groups in said compound component F.
Inventors
- 👤 Masatake Kato
- 👤 Keiji Ikemori
- 👤 Tsunefumi Tanaka
- 👤 Kazuo Tanaka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 07:44
CPC Classifications
G; G02; G02B; G02B15/00; G02B15/14; G02B15/16; G02B15/163; G02B15/167; G02B15/173; G02B15/145; G02B15/1451; G02B15/145129
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
119 words
A zoom lens comprising: a plurality of lens units axially movable for the zooming of said zoom lens and stationary during focusing; and a compound lens unit, having a focusing sub-unit axially movable for focusing from an infinitely distant object to a close object and a further sub-unit stationary during focusing, lying on the image side of at least one of said plurality of lens units, and arranged upon zooming to move axially as a unit along with said plurality of lens units; said focusing and further lens units having substantially the same but opposite refractive powers so that the overall power of the compound lens unit is so small as to have substantially no influence on the zooming.
Claim 2
Dependent Claim
119 words
A zoom lens comprising: a plurality of lens units axially movable for the zooming of said zoom lens and stationary during focusing; and a compound lens unit, having a focusing sub-unit axially movable for focusing from an infinitely distant object to a close object and a further sub-unit stationary during focusing, lying on the image side of at least one of said plurality of lens units, and arranged upon zooming to move axially as a unit along with said plurality of lens units; said focusing and further lens units having substantially the same but opposite refractive powers so that the overall power of the compound lens unit is so small as to have substantially no influence on the zooming.
Claim 3
Dependent Claim
46 words
A zoom lens according to claim 1, satisfying -1/3f.sub.T <1/f.sub.F <1/3f.sub.T where f F is the focal length of said compound lens unit, and f T is the focal length of the entire system at the telephoto side of the zooming range of said zoom lens.
Claim 4
Dependent Claim
25 words
A zoom lens according to claim 1, wherein said focusing sub-unit has a positive refractive power and the other sub-unit has a negative refractive power.
Claim 5
Dependent Claim
38 words
A zoom lens according to claim 1, wherein at least one of said plurality of lens units axially moves to vary the magnification power and another one axially moves to compensate for the shift of the image plane.
Claim 6
Dependent Claim
85 words
A zoom lens comprising: a plurality of lens units axially movable for zooming and stationary during focusing from an infinitely distant object to a close object; and a compound lens unit having a plurality of sub-units arranged to move axially along with said lens units when zooming, and to change their axial separations to effect focusing, whereby satisfying -1/3f.sub.T <1/f.sub.F <1/3f.sub.T where f F is the focal length of said compound lens unit and f T is the longest focal length of the entire system.
Claim 7
Dependent Claim
85 words
A zoom lens comprising: a plurality of lens units axially movable for zooming and stationary during focusing from an infinitely distant object to a close object; and a compound lens unit having a plurality of sub-units arranged to move axially along with said lens units when zooming, and to change their axial separations to effect focusing, whereby satisfying -1/3f.sub.T <1/f.sub.F <1/3f.sub.T where f F is the focal length of said compound lens unit and f T is the longest focal length of the entire system.
References Cited (Backward Citations)
US3286592A
Cited
US4054371A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-10-26 | 1991-04-27 | 1991-10-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-10-26 | 1995-04-27 | 1995-10-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-10-26 | 1999-04-27 | 1999-10-27 | $7700.00 | Window Closed / Lapsed |