Patent US4443973A successfully refreshed from Google Patents.
Patent US5056900A successfully refreshed from Google Patents.
US5056900A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Zoom lens
Assignee: Canon Inc
•
Filing: 1990-10-10
•
Granted: 1991-10-15
•
Expires: 2010-10-10
Abstract
Abstract A zoom lens comprising a first lens unit of positive power, a second lens unit of negative power as the variator, a third lens unit of negative power as the compensator, and a fourth lens unit of positive power stationary during zooming, the fourth lens unit being composed of a bi-convex first lens, a positive second lens, a negative third lens of strong concave curvature at the front, a positive fourth lens, a fifth lens of strong concave curvature at the rear, and a positive sixth lens, and satisfying the following condition: 0.5<D/Fw<1.5 where D is the air separation between the fourth and fifth lenses, and Fw is the shortest focal length of the entire lens system.
Inventors
- 👤 Hitoshi Mukaiya
- 👤 Akihisa Horiuchi
- 👤 Yasunori Murata
- 👤 Akihiro Nishio
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 19:48
CPC Classifications
G; G02; G02B; G02B15/00; G02B15/14; G02B15/144; G02B15/1441; G02B15/144109
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
159 words
A zoom lens comprising: when counted from the object side, a first lens unit having a positive refractive power; a second lens unit having a negative refractive power and arranged to move along an optical axis for varying the image magnification; a third lens unit arranged to move along the optical axis as the image magnification is varied; and a fourth lens unit having a positive refractive power and arranged to be stationary, said fourth lens unit including a ti-convex first lens, when counted from the object side, a positive second lens, a negative third lens having a strong concave surface facing the object side, a positive fourth lens, a fifth lens having a strong concave surface facing the image side, and a positive sixth lens, and satisfying the following condition: 0.5<D/Fw<1.5 where D is the air separation between said positive fourth lens and said fifth lens, and Fw is the shortest focal length of the entire lens system.
Claim 2
Dependent Claim
159 words
A zoom lens comprising: when counted from the object side, a first lens unit having a positive refractive power; a second lens unit having a negative refractive power and arranged to move along an optical axis for varying the image magnification; a third lens unit arranged to move along the optical axis as the image magnification is varied; and a fourth lens unit having a positive refractive power and arranged to be stationary, said fourth lens unit including a ti-convex first lens, when counted from the object side, a positive second lens, a negative third lens having a strong concave surface facing the object side, a positive fourth lens, a fifth lens having a strong concave surface facing the image side, and a positive sixth lens, and satisfying the following condition: 0.5<D/Fw<1.5 where D is the air separation between said positive fourth lens and said fifth lens, and Fw is the shortest focal length of the entire lens system.
Claim 3
Dependent Claim
31 words
A zoom lens according to claim 1, satisfying the following condition: -0.3<B<-0.08 where β is the overall magnification of said second lens to said sixth lens of said fourth lens unit.
Claim 4
Dependent Claim
33 words
A zoom lens according to claim 1, satisfying the following condition: -1.5<φ.sub.B /φ.sub.A <0 where φ A and φ B are the curvatures of front and rear surfaces of said fourth lens respectively.
Claim 5
Dependent Claim
46 words
A zoom lens according to claim 1, satisfying the following condition: 0.9<F.sub.B /F.sub.A <2.4 where F A is the overall focal length of said second lens to said fourth lens, and F B is the overall focal length of said fifth lens and said sixth lens.
References Cited (Backward Citations)
US4720181A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-10-14 | 1995-04-15 | 1995-10-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-10-14 | 1999-04-15 | 1999-10-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-10-14 | 2003-04-15 | 2003-10-15 | $7700.00 | Window Closed / Lapsed |