Patent US4871240A successfully refreshed from Google Patents.
US4871240A
Expired / Lapsed
US
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Zoom lens system having a lens unit with a variable refractive power
Assignee: Canon Inc
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Filing: 1987-12-17
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Granted: 1989-10-03
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Expires: 2007-12-17
Abstract
Abstract Disclosed is a zoom lens comprising a first lens group having a first lens unit movable on the optic axis to effect a magnification change, a correcting lens unit whose refractive power is variable to correct the movement of the image surface during the magnification change, and a second lens group having a second lens unit whose refractive power is variable for the magnification change.
Inventors
- 👤 Shigeyuki Suda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 21:08
CPC Classifications
G; G02; G02B; G02B15/00; G02B15/14; G02B15/142; G02B15/143
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
52 words
A zoom lens comprising a first lens unit movable on an optic axis for a first magnification change, a second lens unit whose refractive power is variable for a second magnification change, and a correcting lens unit for correcting the movement of an image surface during a first or second magnification change.
Claim 2
Dependent Claim
52 words
A zoom lens comprising a first lens unit movable on an optic axis for a first magnification change, a second lens unit whose refractive power is variable for a second magnification change, and a correcting lens unit for correcting the movement of an image surface during a first or second magnification change.
Claim 3
Dependent Claim
44 words
A zoom lens according to claim 1, wherein said first lens unit has a first magnification change in a first range, and said second lens unit has a second magnification change in a second range that is succeeding to said first magnification change range.
Claim 4
Dependent Claim
38 words
A zoom lens according to claim 1, wherein said lens units are disposed along said optic axis from the object side in the order of said first lens unit, said correcting lens unit and said second lens unit.
Claim 5
Dependent Claim
37 words
A zoom lens according to claim 1, wherein said correcting lens unit is a single unit and corrects the movement of the image surface by said first and second lens units by varying the refractive power thereof.
Claim 6
Dependent Claim
94 words
A zoom lens according to claim 1, wherein said correcting lens unit comprises a first correcting lens sub-unit and a second correcting lens sub-unit both movable along an optic axis, said first correcting lens sub-unit is positioned on the image surface side of said first lens unit so as to correct the movement of the image surface by said first lens unit, and said second correcting lens sub-unit is positioned on the object side of said second lens unit so as to correct the movement of the image surface by said second lens unit.
Claim 7
Dependent Claim
17 words
A zoom lens according to claim 4, wherein a focusing is effected by said correcting lens unit.
Claim 8
Dependent Claim
16 words
A zoom lens according to claim 5, wherein said first lens unit comprises a focusing lens.
Claim 9
Dependent Claim
45 words
A zoom lens according to claim 6, wherein said correcting lens unit comprises a radius of curvature that is variable and satisfies a substantially aplanatic condition relative to an on-axis object point at a position in an area of variation of the radius of curvature.
Claim 10
Dependent Claim
45 words
A zoom lens according to claim 6, wherein said second lens unit comprises a radius of curvature that is variable and satisfies a substantially concentric condition relative to an on-axis object point at a position in an area of variation of the radius of curvature.
Claim 11
Dependent Claim
50 words
A zoom lens according to claim 7, wherein said second lens unit comprises a radius of curvature that is variable and satisfies a substantially concentric condition relative to an on-axis object point at a position on the wide angle side in an area of variation of the radius of curvature.
Claim 12
Dependent Claim
65 words
A zoom lens comprising a first lens group having a first lens unit movable on an optic axis for a first magnification change, a second lens group having a second lens unit whose refractive power is variable for a second magnification change, and a correcting lens unit for correcting the movement of an image surface by said first lens unit and said second lens unit.
Claim 13
Dependent Claim
65 words
A zoom lens comprising a first lens group having a first lens unit movable on an optic axis for a first magnification change, a second lens group having a second lens unit whose refractive power is variable for a second magnification change, and a correcting lens unit for correcting the movement of an image surface by said first lens unit and said second lens unit.
Claim 14
Dependent Claim
30 words
A zoom lens according to claim 11, wherein said correcting lens unit is positioned between said first lens group and said second lens group and varies the refractive power thereof.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-10-02 | 1993-04-03 | 1993-10-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-10-02 | 1997-04-03 | 1997-10-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-10-02 | 2001-04-03 | 2001-10-03 | $7700.00 | Window Closed / Lapsed |