US4699474A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Compact zoom lens
Assignee: Ricoh Co Ltd
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Filing: 1985-07-31
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Granted: 1987-10-13
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Expires: 2005-07-31
Abstract
Abstract A zoom lens for a color video camera in which zoom ratio is 6 and F number is approximately 1.4. The zoom lens comprises a positive first group for focusing, a negative second unit for zooming, a negative third unit which is a compensator, a positive fourth unit for forming an incident divergent bundle of rays into a parallel or converging bundle of rays, and a fifth unit in the form of a relay lens composed of a front component and a rear component. Parameters, especially such as a refracting power of the first unit and second unit, are suitably selected whereby a zoom lens which is compact and which aberrations are well compensated is obtained.
Inventors
- 👤 Toshiro Ozawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 16:47
CPC Classifications
G; G02; G02B; G02B15/00; G02B15/14; G02B15/145; G02B15/1451; G02B15/145125
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
388 words
A zoom lens comprising, successively from an object side, a first lens unit having a positive refracting power, a second lens unit having a negative refracting power, a third lens unit having a negative refracting power, a fourth lens unit having a positive refracting power, and a fifth lens unit having a positive refracting power with a stop sandwiched therebetween, said first lens unit comprising a lens unit for focusing consisting of a cemented lens of a first negative lens and a second positive lens and a third positive meniscus lens, said second lens unit comprising a lens unit consisting of a fourth negative lens and a cemented lens of a fifth negative lens and a sixth positive lens, said lens unit being moved as zooming takes place to vary a focal length, said third lens unit comprising a lens unit consisting of a seventh negative lens for principally maintaining a focal position constant by movement thereof as zooming takes place; said fourth lens unit comprising a lens unit consisting of two positive eighth and ninth lenses for compensating a divergent luminuous flux emitted from a zoom system composed of said first, second and third units into a bundle of rays or a gently converging luminous flux, said fifth lens unit comprising a lens group for focusing comprising a front component consisting of a positive tenth lens, a positive eleventh meniscus lens and a negative twelfth lens and a rear component consisting of a negative thirteenth lens, a positive fourteenth lens and a positive meniscus fifteenth lens, said zoom lens being satisfied with the following conditions: ##EQU2## where F w : Shortest focal length of the entire system F I : Focal length of the first lens unit F II : Focal length of the second lens unit F V : Focal length of the fifth lens unit r 7 : Radius of curvature of a surface on the image side of the fourth lens r 8 : Radius of curvature of a surface on the object side of the fifth lens n i : Refractive index of the i lens ν i : Abbe's number of the i lens f 1 : Focal length of the front component of the fifth lens unit d 22 : Spacing between the negative 12th lens and the negative 13th lens.
Claim 2
Dependent Claim
388 words
A zoom lens comprising, successively from an object side, a first lens unit having a positive refracting power, a second lens unit having a negative refracting power, a third lens unit having a negative refracting power, a fourth lens unit having a positive refracting power, and a fifth lens unit having a positive refracting power with a stop sandwiched therebetween, said first lens unit comprising a lens unit for focusing consisting of a cemented lens of a first negative lens and a second positive lens and a third positive meniscus lens, said second lens unit comprising a lens unit consisting of a fourth negative lens and a cemented lens of a fifth negative lens and a sixth positive lens, said lens unit being moved as zooming takes place to vary a focal length, said third lens unit comprising a lens unit consisting of a seventh negative lens for principally maintaining a focal position constant by movement thereof as zooming takes place; said fourth lens unit comprising a lens unit consisting of two positive eighth and ninth lenses for compensating a divergent luminuous flux emitted from a zoom system composed of said first, second and third units into a bundle of rays or a gently converging luminous flux, said fifth lens unit comprising a lens group for focusing comprising a front component consisting of a positive tenth lens, a positive eleventh meniscus lens and a negative twelfth lens and a rear component consisting of a negative thirteenth lens, a positive fourteenth lens and a positive meniscus fifteenth lens, said zoom lens being satisfied with the following conditions: ##EQU2## where F w : Shortest focal length of the entire system F I : Focal length of the first lens unit F II : Focal length of the second lens unit F V : Focal length of the fifth lens unit r 7 : Radius of curvature of a surface on the image side of the fourth lens r 8 : Radius of curvature of a surface on the object side of the fifth lens n i : Refractive index of the i lens ν i : Abbe's number of the i lens f 1 : Focal length of the front component of the fifth lens unit d 22 : Spacing between the negative 12th lens and the negative 13th lens.
References Cited (Backward Citations)
US3336094A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-10-12 | 1991-04-13 | 1991-10-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-10-12 | 1995-04-13 | 1995-10-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-10-12 | 1999-04-13 | 1999-10-13 | $7700.00 | Window Closed / Lapsed |