Patent US5325236A successfully refreshed from Google Patents.
US5325236A
Expired / Lapsed
US
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Ultra-wide-angle type zoom lens
Assignee: Canon Inc
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Filing: 1992-02-27
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Granted: 1994-06-28
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Expires: 2012-02-27
Abstract
Abstract An ultra-wide-angle type zoom lens is disclosed, comprising, in the order from the object side, a negative first lens unit, a negative second lens unit and a positive third lens unit, wherein zooming from the wide-angle end to the telephoto end is performed by differentially moving the second and third lens units.
Inventors
- 👤 Tsunefumi Tanaka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 20:50
CPC Classifications
G; G02; G02B; G02B15/00; G02B15/14; G02B15/16; G02B15/177
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
65 words
A wide-angle type zoom lens comprising: in the order from an object side, a first lens unit, which is closest to the object side, having a negative refractive power; a second lens unit having a negative refractive power; and a third lens unit having a positive refractive power, wherein said second lens unit and said third lens unit are made to move differentially for zooming.
Claim 2
Dependent Claim
65 words
A wide-angle type zoom lens comprising: in the order from an object side, a first lens unit, which is closest to the object side, having a negative refractive power; a second lens unit having a negative refractive power; and a third lens unit having a positive refractive power, wherein said second lens unit and said third lens unit are made to move differentially for zooming.
Claim 3
Dependent Claim
19 words
A wide-angle type zoom lens according to claim 1, wherein focusing is performed by moving said second lens unit.
Claim 4
Dependent Claim
49 words
A wide-angle type zoom lens according to claim 1, satisfying the following conditions: |f.sub.1 |>|f.sub.2 | 1.5<|f.sub.2 /f.sub.W |<3 where f 1 and f 2 are focal lengths of said first and second lens units, respectively, and f W is the shortest focal length of the entire lens system.
Claim 5
Dependent Claim
31 words
A wide-angle type zoom lens according to claim 1, wherein said first lens unit comprises a negative meniscus lens and a positive lens having an aspheric surface facing the object side.
Claim 6
Dependent Claim
33 words
A wide-angle type zoom lens according to claim 4, wherein said aspheric surface of said positive lens is in such a shape that a positive refractive power gets progressively stronger toward a margin.
Claim 7
Dependent Claim
26 words
A wide-angle type zoom lens according to claim 5, wherein said third lens unit includes a positive lens having an aspheric surface facing an image side.
Claim 8
Dependent Claim
27 words
A wide-angle type zoom lens according to claim 6, wherein said positive lens of said third lens unit is positioned on the image side of a stop.
Claim 9
Dependent Claim
72 words
A wide-angle type zoom lens comprising: in the order from an object side, a first lens unit, which is closest to the object side, having a negative refractive power; a second lens unit having a negative refractive power; and a third lens unit having a positive refractive power, wherein said first lens unit is fixed and said second lens unit and said third lens unit are made to move differentially for zooming.
Claim 10
Dependent Claim
72 words
A wide-angle type zoom lens comprising: in the order from an object side, a first lens unit, which is closest to the object side, having a negative refractive power; a second lens unit having a negative refractive power; and a third lens unit having a positive refractive power, wherein said first lens unit is fixed and said second lens unit and said third lens unit are made to move differentially for zooming.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-06-27 | 1997-12-27 | 1998-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-06-27 | 2001-12-27 | 2002-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-06-27 | 2005-12-27 | 2006-06-28 | $7700.00 | Window Closed / Lapsed |