Patent DE3119295C2 successfully refreshed from Google Patents.
US4984878A
Expired / Lapsed
US
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Ojective lens for endoscope
Assignee: Fujinon Corp
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Filing: 1989-08-08
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Granted: 1991-01-15
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Expires: 2009-08-08
Abstract
Abstract An objective lens particularly suitable for use in endoscope, employing a lens system which is composed of four single lenses, namely, composed of, from the object side, a first lens L 1 consisting of a negative lens having the concave surface thereof on the object side, a second lens L 2 consisting of a positive lens having a surface of smaller radius of curvature disposed on the object side, a third lens L 3 consisting of a positive lens having a surface of smaller radius of curvature on the image side, and a fourth lens L 4 consisting of a positive lens. In this lens construction, the respective lenses L 1 to L 4 are adapted to satisfy the conditions of n 1 >1.70, γ 1 >40.0, γ 3 <42.5, n 5 >1.60, γ 5 >50.0, n 7 >1.60, and γ 7 >50.0 (where n 1 , n 5 and n 7 are refractive indices of the first lens L 1 , third lens L 3 and fourth lens L 4 relative to line d, respectively, and γ 1 , γ 3 , γ 5 and γ 7 are Abbe's numbers of the first to fourth lenses L 1 and L 4 , respectively.)
Inventors
- 👤 Hitoshi Miyano
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 10:47
CPC Classifications
G; G02; G02B; G02B9/00; G02B9/34; G02B23/00; G02B23/24; G02B23/2407; G02B23/2423; G02B23/243; G02B13/00; G02B13/22
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
211 words
An objective lens for an endoscope, having a lens system consisting of four single lenses designated as first lens L 1 , second lens L 2 , third lens L 3 and fourth lens L 4 from the object side, wherein: said first lens L 1 consists of a negative lens having a concave surface on the image side; said second lens L 2 consists of a positive lens having a surface of a smaller radius of curvature on the object side; said third lens L 3 consists of a positive lens having a surface of a smaller radius of curvature on the image side; and said fourth lens L 4 consists of a positive lens; said first to fourth lenses L 1 to L 4 of said lens system being arranged to satisfy the following conditions (1) to (4). ##EQU1## where n 1 , n 5 and n 7 are refractive indices of said first lens L 1 , third lens L 3 and fourth lens L 4 relative to line d, and γ 1 , γ 3 , γ 5 and V 7 are Abbe's numbers of said first lens L 1 , second lens L 2 , third lens L 3 and fourth lens L 4 , respectively.
Claim 2
Dependent Claim
211 words
An objective lens for an endoscope, having a lens system consisting of four single lenses designated as first lens L 1 , second lens L 2 , third lens L 3 and fourth lens L 4 from the object side, wherein: said first lens L 1 consists of a negative lens having a concave surface on the image side; said second lens L 2 consists of a positive lens having a surface of a smaller radius of curvature on the object side; said third lens L 3 consists of a positive lens having a surface of a smaller radius of curvature on the image side; and said fourth lens L 4 consists of a positive lens; said first to fourth lenses L 1 to L 4 of said lens system being arranged to satisfy the following conditions (1) to (4). ##EQU1## where n 1 , n 5 and n 7 are refractive indices of said first lens L 1 , third lens L 3 and fourth lens L 4 relative to line d, and γ 1 , γ 3 , γ 5 and V 7 are Abbe's numbers of said first lens L 1 , second lens L 2 , third lens L 3 and fourth lens L 4 , respectively.
Claim 3
Dependent Claim
112 words
An objective lens as defined in claim 1, wherein said first to fourth lenses L 1 to L 4 are arranged to satisfy further the following conditions (5) and (6): (5) d.sub.1 +d.sub.2 +d.sub.3 <2.5f, and (6) 2f<r.sub.7 /(n.sub.7 -1.0)<3f where d 1 is the center thickness of said first lens L 1 , d 2 is the airspace between said first and second lenses L 1 and L 2 , d 3 is the center thickness of said second lens L 2 , f is the resultant focal length of said system, and r 7 is the radius of curvature of the object-side surface of said fourth lens L 4 .
Claim 4
Dependent Claim
25 words
An objective lens as defined in claim 1, further comprising a stop interposed between said second and third lenses L 2 and L 3 .
Claim 5
Dependent Claim
31 words
An objective lens as defined in claim 1, wherein said lens system has the image plane thereof located to coincide with the image-side surface of said fourth lens L 4 .
Claim 6
Dependent Claim
32 words
An objective lens as defined in claim 4, wherein said the focus of said lens system is adjusted by shifting said fourth lens L 4 in the direction of the optical axis.
Claim 7
Dependent Claim
28 words
An objective lens as defined in claim 1, wherein said lens system is arranged to have an imaging position located rearward of said fourth lens L 4 .
Claim 8
Dependent Claim
31 words
An objective lens as defined in claim 5, wherein the focus of said lens system is adjusted by varying the distance between said fourth lens L 4 and said image plane.
References Cited (Backward Citations)
US4674844A
Cited
US4806001A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-01-14 | 1994-07-16 | 1995-01-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-01-14 | 1998-07-16 | 1999-01-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-01-14 | 2002-07-16 | 2003-01-15 | $7700.00 | Window Closed / Lapsed |