US3885862A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Zoom lens
Assignee: Yashica Co Ltd
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Filing: 1973-10-05
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Granted: 1975-05-27
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Expires: 1993-10-05
Abstract
Abstract A zoom lens composed of four groups of lenses which have a common optical axis with the first three groups which are situated from the front toward the rear along the common optical axis be movable along the optical axis. The first group of lenses consists of three lenses the first two of which have a combined focal length which when divided by the focal length of the third lens is less than 3 but greater than 2. The radius of the rear surface of the second lens of the first group divided into 1 is less than 0 but greater than -1 divided by 5 times the focal length of the first group. The second group of lenses includes three lenses forming the fourth, fifth, and sixth lens of the zoom lens, with the fifth and sixth lens contacting each other. The radius of the front surface of the fifth lens divided by the radius of the rear surface of the sixth lens has a value which is less than 2.5 but greater than 1.0. The difference between the refractive indices of the fifth and sixth lenses with respect to the d-line divided by the radius of curvature of the common surface between fifth and sixth lenses and multiplied by the focal length of the second group of lenses is less than 0.15.
Inventors
- 👤 Yoshisato Fujioka
- 👤 Tetsuro Ishizuka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 15:21
CPC Classifications
G; G02; G02B; G02B15/00; G02B15/14; G02B15/144; G02B15/1441; G02B15/144109
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
382 words
In a zoom lens having a front end to be directed toward an object to be photographed and a rear end to be directed toward an image plane of a camera, first means situated at said front end for carrying out an image-composing function with respect to a finite object, second means situated behind said first means for varying magnification, said first and second means having a common optical axis and being movable therealong, third means situated along said optical axis behind said second means and being movable therealong for compensating for a change in focal point produced by movement of said second means along said optical axis, and fourth means situated behind said third means along said optical axis for composing an image, said fourth means being fixed with respect to said optical axis, said first means including a first lens group of positive refracting power and consisting of three lens members which include from the front toward the rear a first negative meniscus lens having a forwardly directed convex surface, a second positive lens having a forwardly directed convex surface of greater curvature than its rearwardly directed convex surface, with said forwardly directed convex surface of said second lens contacting the rear surface of said first lens for providing a focusing function therewith, and a third positive meniscus lens having a forwardly directed convex surface, said second means including a second lens group having a negative refracting power and consisting of three lens members forming the fourth, fifth, and sixth lens, respectively, of the zoom lens, said fourth lens being a negative meniscus lens having a forwardly directed convex surface, said fifth lens being a positive meniscus lens having a rearwardly directed convex surface of greater curvature than its forwardly directed surface, and said sixth lens being a negative lens whose concave forwardly directed surface is of greater curvature than its rearwardly directed surface, said fifth and sixth lenses engaging each other and having a diverging function, said third means including a third lens group having a negative refracting power and consisting of a negative meniscus lens having a forwardly directed concave surface, said fourth means including a fourth lens group having a positive refracting power and consisting of four positive lens members and at least one negative lens member.
Claim 2
Dependent Claim
382 words
In a zoom lens having a front end to be directed toward an object to be photographed and a rear end to be directed toward an image plane of a camera, first means situated at said front end for carrying out an image-composing function with respect to a finite object, second means situated behind said first means for varying magnification, said first and second means having a common optical axis and being movable therealong, third means situated along said optical axis behind said second means and being movable therealong for compensating for a change in focal point produced by movement of said second means along said optical axis, and fourth means situated behind said third means along said optical axis for composing an image, said fourth means being fixed with respect to said optical axis, said first means including a first lens group of positive refracting power and consisting of three lens members which include from the front toward the rear a first negative meniscus lens having a forwardly directed convex surface, a second positive lens having a forwardly directed convex surface of greater curvature than its rearwardly directed convex surface, with said forwardly directed convex surface of said second lens contacting the rear surface of said first lens for providing a focusing function therewith, and a third positive meniscus lens having a forwardly directed convex surface, said second means including a second lens group having a negative refracting power and consisting of three lens members forming the fourth, fifth, and sixth lens, respectively, of the zoom lens, said fourth lens being a negative meniscus lens having a forwardly directed convex surface, said fifth lens being a positive meniscus lens having a rearwardly directed convex surface of greater curvature than its forwardly directed surface, and said sixth lens being a negative lens whose concave forwardly directed surface is of greater curvature than its rearwardly directed surface, said fifth and sixth lenses engaging each other and having a diverging function, said third means including a third lens group having a negative refracting power and consisting of a negative meniscus lens having a forwardly directed concave surface, said fourth means including a fourth lens group having a positive refracting power and consisting of four positive lens members and at least one negative lens member.
Claim 3
Dependent Claim
154 words
The combination of claim 1 and wherein for a focal length range of the zoom lens f 9.0 * 30.0 mm, for an aperture ratio 1 : 1.9, for a diagonal of effective image surface of 7.1 mm, and for focal lengths for the first, second and third lens groups which are respectively f1 31.4, f2 - 10.70, and f3 -21.0, the zoom lens has the data presented in the following table headed Embodiment 1 (see FIG. 1), where the zoom lens includes 12 lenses with the successive surfaces of the lenses from the front to the rear having the radii of curvature indicated in the first column, where the distances between the successive lens surfaces have the values indicated in the second column, where the refractive indices of the successive lenses with respect to the d-line are indicated in the third column, and where the Abbe numbers are indicated in the fourth column:
Claim 4
Dependent Claim
154 words
The combination of claim 1 and wherein for a focal length range of the zoom lens f 9.0 *30.0 mm, for an aperture ratio 1 : 1.9, for a diagonal of effective image surface of 7.1 mm, and for focal lengths for the first, second and third lens groups which are respectively f1 31.4, f2 - 10.70, and f3 - 21.0, the zoom lens has the data presented in the following table headed Embodiment 2 (see FIG. 2), where the zoom lens includes 13 lenses with the successive surfaces of the lenses from the front to the rear having the radii of curvature indicated in the first column, where the distances between the successive lens surfaces have the values indicated in the second column, where the refractive indices of the successive lenses with respect to the d-line are indicated in the third column, and where the Abbe numbers are indicated in the fourth column:
Claim 5
Dependent Claim
151 words
The combination of claim 1 and wherein for a focal length range of the zoom lens f 9.0 *30.0 mm, for an aperture ratio 1 : 1.9, for a diagonal of effective image surface of 7.1 mm, and for focal lengths for the first, second and third lens groups which are respectively f1 31.4, f2 - 10.70, and f3 -21.0, the zoom lens has the date presented in the following table headed Embodiment 3 (see FIG. 3), where the zoom lens includes 13 lenses with successive surfaces of the lenses from the front to the rear having the radii of curvature indicated in the first column, where the distances between the successive lens surfaces have the values indicated in the second column, where the refractive indices of the successive lenses with respect to the d-line are indicated in the third column, where the Abbe numbers are indicated in the fourth column:
Claim 6
Dependent Claim
109 words
The combination of claim 1 and wherein said lens of said third means forms the seventh lens of the zoom lens while the five lens members of said fourth means respectively form the eighth, ninth, and tenth, eleventh, and twelfth lens, respectively, of the zoom lens, said eighth and ninth lenses both being positive and respectively having convex surfaces directed toward each other and each consisting of at least one lens element, said tenth lens being a negative biconcave lens, said eleventh lens being a positive lens having a rearwardly directed convex surface of greater curvature than its forwardly directed surface, and said twelfth lens being a positive lens.
Claim 7
Dependent Claim
29 words
The combination of claim 5 and wherein said eighth lens includes positive and negative lens elements cemented to each other and forming together a lens of positive refracting power.
Claim 8
Dependent Claim
28 words
The combination of claim 5 and wherein said ninth lens consists of positive and negative lens elements cemented to each other and together having a positive refracting power.
Claim 9
Dependent Claim
20 words
The combination of claim 5 and wherein said eighth and ninth lenses consist each only of a single lens element.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-05-26 | 1978-11-25 | 1979-05-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-26 | 1982-11-25 | 1983-05-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-26 | 1986-11-25 | 1987-05-27 | $7700.00 | Window Closed / Lapsed |