US5343329A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Zoom lens system
Assignee: Pentax Corp
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Filing: 1992-10-09
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Granted: 1994-08-30
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Expires: 2012-10-09
Abstract
Abstract The improved zoom lens system comprises at least three lens groups which are arranged, in order from the object side, as a first lens group having a positive focal length, a second lens group having a positive focal length and a third lens group having a negative focal length, wherein, when zooming is carried out from the wide-angle to the narrow-angle end, said first, second and third lens groups are moved towards the object so that the distance between said first and second lens groups is increased whereas the distance between said second and third lens groups is decreased. The system is characterized in that each of the first and second lens groups has at least one aspheric surface.
Inventors
- 👤 Takayuki Ito
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 20:47
CPC Classifications
G; G02; G02B; G02B15/00; G02B15/14; G02B15/16; G02B15/143; G02B15/1431; G02B15/143103
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
115 words
In a zoom lens system comprising at least three lens groups which are arranged, in order from the object side, as a first lens group having a positive focal length, a second lens group having a positive focal length and a third lens group having a negative focal length, wherein, when zooming is carried out from the extreme wide-angle to the extreme narrow-angle end, said first, second and third lens groups are moved towards the object so that the distance between said first and second lens groups is increased whereas the distance between said second and third lens groups is decreased, each of said first and second lens groups has at least one aspheric surface.
Claim 2
Dependent Claim
115 words
In a zoom lens system comprising at least three lens groups which are arranged, in order from the object side, as a first lens group having a positive focal length, a second lens group having a positive focal length and a third lens group having a negative focal length, wherein, when zooming is carried out from the extreme wide-angle to the extreme narrow-angle end, said first, second and third lens groups are moved towards the object so that the distance between said first and second lens groups is increased whereas the distance between said second and third lens groups is decreased, each of said first and second lens groups has at least one aspheric surface.
Claim 3
Dependent Claim
96 words
A zoom lens system according to claim 1 wherein said aspheric surface satisfy the following conditions: (a) -30<ΔI.sub.2 <0 (b) -1<ΔIII.sub.1 <0 where ΔI 2 : the sum of variations in the coefficient of the third order spherical aberration due to all aspheric surfaces in the second lens group (the aberration coefficient is such as is calculated with the focal length of the overall system at the wide-angle end being taken as 1.0); and ΔIII 1 : the sum of variations in the coefficient of astigmatism due to all aspheric surfaces in the first lens group.
Claim 4
Dependent Claim
40 words
A zoom lens system according to claim 1 wherein said third lens group comprises two lens elements which are arranged, in order from the object side, as a positive and a negative element and has at least one aspheric surface.
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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) | 1997-08-29 | 1998-02-28 | 1998-08-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-08-29 | 2002-02-28 | 2002-08-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-08-29 | 2006-02-28 | 2006-08-30 | $7700.00 | Window Closed / Lapsed |