Patent US4712883A successfully refreshed from Google Patents.
US4712883A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Rear focus zoom lens
Assignee: Canon Inc
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Filing: 1984-01-17
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Granted: 1987-12-15
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Expires: 2004-01-17
Abstract
Abstract The disclosed zoom lens includes, from front to rear, a magnification-power variable lens assembly which serves for zooming and an image forming lens assembly which is stationary during zooming. The image forming assembly has a lens component B of negative refractive power which is preceded by at least one lens component A movable for focusing and which is followed by at least one lens component C movable for focusing. This structure makes achievement of a compact form and good stability in aberration correction possible throughout the entire focusing range.
Inventors
- 👤 Masatake Kato
- 👤 Sadahiko Tsuji
- 👤 Toshiaki Asano
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 13:12
CPC Classifications
G; G02; G02B; G02B15/00; G02B15/14; G02B15/144; G02B15/1441
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
94 words
A zoom lens of the rear focusing type comprising: from front to rear, a magnification varying assembly having a plurality of movable lens components movable during zooming and stationary during focusing, and an image forming assembly stationary during zooming, said image forming assembly including a lens component B having negative refractive power and movable at a time of focusing, a lens component A on the object side of said lens component B and movable when focusing, and a lens component C on the image side of said lens group B and movable when focusing.
Claim 2
Dependent Claim
94 words
A zoom lens of the rear focusing type comprising: from front to rear, a magnification varying assembly having a plurality of movable lens components movable during zooming and stationary during focusing, and an image forming assembly stationary during zooming, said image forming assembly including a lens component B having negative refractive power and movable at a time of focusing, a lens component A on the object side of said lens component B and movable when focusing, and a lens component C on the image side of said lens group B and movable when focusing.
Claim 3
Dependent Claim
22 words
A zoom lens according to claim 1, wherein said lens component A and said lens component C each have a positive power.
Claim 4
Dependent Claim
21 words
A zoom lens according to claim 1, wherein said lens component A and said lens component C move as a unit.
Claim 5
Dependent Claim
24 words
A zoom lens according to claim 1, wherein said lens component A and said lens component C move in different relation to each other.
Claim 6
Dependent Claim
25 words
A zoom lens according to claim 1, wherein the lens component A has a negative power and the lens component C has a positive power.
Claim 7
Dependent Claim
47 words
A zoom lens according to claim 1, wherein each lens component moves such that the separation between the lens component A and the lens component B increases and the separation between the lens component B and the lens component C decreases when focusing to a short distance.
Claim 8
Dependent Claim
116 words
A zoom lens of the rear focusing type comprising: a lens component B movable when focusing and having a negative power; a lens component A arranged on the object side of said lens component B at a point adjacent to said lens component B and movable when focusing; a lens component C arranged on the image side of said lens component B at a point adjacent to said lens component B and movable when focusing, said lens component B, said lens component A and said lens component C being stationary during zooming; and a magnification varying lens group arranged on the object side of said lens component A and movable when zooming and stationary when focusing.
Claim 9
Dependent Claim
116 words
A zoom lens of the rear focusing type comprising: a lens component B movable when focusing and having a negative power; a lens component A arranged on the object side of said lens component B at a point adjacent to said lens component B and movable when focusing; a lens component C arranged on the image side of said lens component B at a point adjacent to said lens component B and movable when focusing, said lens component B, said lens component A and said lens component C being stationary during zooming; and a magnification varying lens group arranged on the object side of said lens component A and movable when zooming and stationary when focusing.
Claim 10
Dependent Claim
21 words
A zoom lens according to claim 7, wherein said lens component A and said lens component C have positive refractive powers.
Claim 11
Dependent Claim
25 words
A zoom lens according to claim 7, wherein the lens component A has a negative power and the lens component C has a positive power.
Claim 12
Dependent Claim
47 words
A zoom lens according to claim 7, wherein each lens component moves such that the separation between the lens component B and the lens component A increases and the separation between the lens component B and the lens component C decreases when focusing to a short distance.
Claim 13
Dependent Claim
113 words
A zoom lens of the rear focusing type comprising: a lens component B stationary during focusing and having a negative power; a lens component A arranged on the object side of said lens component B at a point adjacent to said lens component B and movable when focusing; a lens component C arranged on the image side of said lens component B at a point adjacent to said lens component B and movable when focusing, said lens component B, said lens component A and said lens component C being stationary during zooming; and a magnification varying fourth lens group arranged on the object side of said lens component A and movable when zooming.
Claim 14
Dependent Claim
113 words
A zoom lens of the rear focusing type comprising: a lens component B stationary during focusing and having a negative power; a lens component A arranged on the object side of said lens component B at a point adjacent to said lens component B and movable when focusing; a lens component C arranged on the image side of said lens component B at a point adjacent to said lens component B and movable when focusing, said lens component B, said lens component A and said lens component C being stationary during zooming; and a magnification varying fourth lens group arranged on the object side of said lens component A and movable when zooming.
Claim 15
Dependent Claim
21 words
A zoom lens according to claim 11, wherein said lens component A and said lens component C have positive refractive power.
Claim 16
Dependent Claim
25 words
A zoom lens according to claim 11, wherein the lens component A has a negative power and the lens component C has a positive power.
Claim 17
Dependent Claim
50 words
A zoom lens according to claim 11, wherein each lens component moves in such a manner that the separation between the lens component B and the lens component A increases and the separation between the lens component B and the lens component C decreases when focusing to a short distance.
Claim 18
Dependent Claim
94 words
A zoom lens of the rear focusing type comprising: from front to rear, a magnification varying assembly having a plurality of movable lens components movable during zooming and stationary during focusing, and an image forming assembly stationary during zooming, said image forming assembly including a lens component B having negative refractive power and stationary at a time of focusing, a lens component A on the object side of said lens component B and movable when focusing, and a lens component C on the image side of said lens group B and movable when focusing.
Claim 19
Dependent Claim
94 words
A zoom lens of the rear focusing type comprising: from front to rear, a magnification varying assembly having a plurality of movable lens components movable during zooming and stationary during focusing, and an image forming assembly stationary during zooming, said image forming assembly including a lens component B having negative refractive power and stationary at a time of focusing, a lens component A on the object side of said lens component B and movable when focusing, and a lens component C on the image side of said lens group B and movable when focusing.
Claim 20
Dependent Claim
22 words
A zoom lens according to claim 15, wherein said lens component A and said lens component C each have a positive power.
Claim 21
Dependent Claim
21 words
A zoom lens according to claim 15, wherein said lens component A and said lens component C move as a unit.
Claim 22
Dependent Claim
24 words
A zoom lens according to claim 15, wherein said lens component A and said lens component C move in different relation to each other.
Claim 23
Dependent Claim
25 words
A zoom lens according to claim 15, wherein the lens component A has a negative power and the lens component C has a positive power.
Claim 24
Dependent Claim
47 words
A zoom lens according to claim 15, wherein each lens component moves such that the separation between the lens component A and the lens component B increases and the separation between the lens component B and the lens component C decreases when focusing to a short distance.
References Cited (Backward Citations)
US3975089A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-12-14 | 1991-06-15 | 1991-12-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-12-14 | 1995-06-15 | 1995-12-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-12-14 | 1999-06-15 | 1999-12-15 | $7700.00 | Window Closed / Lapsed |