US3788731A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Two point focus variable magnification lens system
Assignee: Canon Inc
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Filing: 1972-07-14
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Granted: 1974-01-29
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Expires: 1992-07-14
Abstract
Abstract WHEREIN F1 IS THE FOCAL LENGTH OF THE FIRST LENS GROUP, F2 IS THE FOCAL LENGTH OF THE SECOND LENS GROUP, S1 IS THE DISTANCE OF A SPECIAL FARTHER SIDE OF OBJECTS FROM THE FRONT END OF THE LENS SYSTEM IN THE CASE OF THE MINIMUM FOCAL LENGTH, S2 IS THE DISTANCE OF A SPECIAL NEARER SIDE OF OBJECTS FROM THE FRONT END OF THE LENS SYSTEM, xi O IS THE DISPLACEMENT LENGTH OF THE SECOND LENS GROUP, K 1 square root z (z: the variation ratio of magnification), ln is the interval between the principal points of the first and second lens groups in the case of the maximum focal length, x is the distance from the front principal point of the first lens group to the point of image formed of an object at a special farther side by the first lens group in the case of the minimum focal length, and y is f2(1 - K)2/k. A two point focus variable magnification lens system which can be focussed at two points, the minimum and maximum focal lengths with different magnifications by the movement of the only second lens groups, and which when focussed at the minimum focal length of the maximum focal length can be made to focus for an object at either of special two distances without performing the focussing operation as far as the following conditions are satisfied,
Inventors
- 👤 M Sugiura
- 👤 R Hirose
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 13:10
CPC Classifications
G; G02; G02B; G02B15/00; G02B15/14; G02B15/16; G02B15/177; G02B15/143; G02B15/1435; G02B15/143507
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
121 words
A lens system with a front end for focusing at a distance s1 from the front end with a magnification zF and at a second distance s2 from the front end of the lens system with a focal length F, said lens system comprising a first lens group at the front of the lens system, a second lens group and a third lens group, said lens groups lying along a common optical axis, said first and third lens groups having substantially fixed positions, said second lens groups being displaceable along the axis a distance xi o, the first lens group having a focal length f1 and the second lens group having the focal length f2, said lens system satisfying the equations:
Claim 2
Dependent Claim
121 words
A lens system with a front end for focusing at a distance s1 from the front end with a magnification zF and at a second distance s2 from the front end of the lens system with a focal length F, said lens system comprising a first lens group at the front of the lens system, a second lens group and a third lens group, said lens groups lying along a common optical axis, said first and third lens groups having substantially fixed positions, said second lens groups being displaceable along the axis a distance xi o, the first lens group having a focal length f1 and the second lens group having the focal length f2, said lens system satisfying the equations:
Claim 3
Dependent Claim
41 words
The system as in claim 1, wherein said first and second and third lens groups have respective dispersive, collective, and collective refraction powers arranged in that order from the object, said third lens group being a fixed position relay lens group.
Claim 4
Dependent Claim
265 words
A two point focus variable magnification lens system which comprises three lens groups having respectively dispersive, collective and collective refraction powers arranged in order from the object side, the first lens group being fixed as a rule, the second lens group being movable so as to vary the magnification, and the third lens group being a fixed position relay lens, and which satisfies the following several dimensions: r: Radii of curvatures of the refraction surfaces in sequence d: Axial widths or air distances of the lens components in sequence N: Refractive indices of the glasses of the lens components in sequence V: Abbe''s number of the same glasses as above in sequence Focal length: f 17.5mm (Object distance: s1 0.8 m) f 25.1mm (Object distance: s2 0.4m) Variation ratio of magnification: 1.45 Aperture ratio 1 : 2 r1 64.018 d1 2.0 N1 1.62041 V1 60.2 r2 30.422 d2 2.0 r3 65.643 d3 4.5 N2 1.65844 V2 50.8 r4 -87.374 d4 2.0 N3 1.74000 V3 28.2 r5 90.547 d5 variable r6 37.646 d6 4.0 N4 1.62230 V4 53.1 r7 -366.922 d7 1.0 N5 1.74077 V5 27.7 r8 123.847 dg 0.2 r9 82.098 d9 3.0 N6 1.51633 V6 64.0 r10 -82.577 d10 variable r11 -13.258 d11 2.5 N7 1.71300 V7 53.1 r12 -11.280d12 2.0 r13 -7.888 d13 5.0 N8 1.78472 V8 25.6 r14 -10.078 d14 0.2 r15 11.548 d15 2.0 N9 1.73500 V9 49.7 r16 9.466 d16 2.0 r17 27.672 d17 2.5 N10 1.67790 V10 50.6 r18 -51.809 Said variable air distance being: When f 17.5 d5 20.803, d10 4.5 When f 25.1 d5 4.263, d10 21.040
Claim 5
Dependent Claim
265 words
A two point focus variable magnification lens system which comprises three lens groups having respectively dispersive, collective and collective refraction powers arranged in order from the object side, the first lens group being fixed as a rule, the second lens group being movable so as to vary the magnification, and the third lens group being a fixed position relay lens, and which satisfies the following several dimensions: r: Radii of curvatures of the refraction surfaces in sequence d: Axial widths or air distances of the lens components in sequence N: Refractive indices of the glasses of the lens components in sequence V: Abbe''s number of the same glasses as above in sequence Focal length: f 17.5mm (Object distance: s1 0.8 m) f 25.1mm (Object distance: s2 0.4m) Variation ratio of magnification: 1.45 Aperture ratio 1 : 2 r1 64.018 d1 2.0 N1 1.62041 V1 60.2 r2 30.422 d2 2.0 r3 65.643 d3 4.5 N2 1.65844 V2 50.8 r4 -87.374 d4 2.0 N3 1.74000 V3 28.2 r5 90.547 d5 variable r6 37.646 d6 4.0 N4 1.62230 V4 53.1 r7 -366.922 d7 1.0 N5 1.74077 V5 27.7 r8 123.847 dg 0.2 r9 82.098 d9 3.0 N6 1.51633 V6 64.0 r10 -82.577 d10 variable r11 -13.258 d11 2.5 N7 1.71300 V7 53.1 r12 -11.280d12 2.0 r13 -7.888 d13 5.0 N8 1.78472 V8 25.6 r14 -10.078 d14 0.2 r15 11.548 d15 2.0 N9 1.73500 V9 49.7 r16 9.466 d16 2.0 r17 27.672 d17 2.5 N10 1.67790 V10 50.6 r18 -51.809 Said variable air distance being: When f 17.5 d5 20.803, d10 4.5 When f 25.1 d5 4.263, d10 21.040
Claim 6
Dependent Claim
236 words
A two point focus variable magnification lens system which comprises three lens groups having respectively dispersive, collective and collective refraction powers arranged in order from the object side, the first lens group being fixed as a rule, the second lens group being movable so as to vary the magnification, and the third lens group being a fixed position relay lens, and which satisfies the following several dimensions: r: Radii of curvatures of the refraction surfaces in sequence d: Axial widths or aid distances of the lens components in sequence N: Refractive indices of the glasses of the lens components in sequence V: Abbe''s numbers of the same glasses as just above in sequence Focal length f 17.5mm (Object distance: s1 0.8 m) f 25.32mm (Object distance: s2 0.4 m) Variation ratio of magnification 1.45 Aperture ratio 1 : 2.8 r1 43.605 d1 1.5 N1 1.62004 V1 36.3 r2 25.3206 d2 variable r3 34.6907 d3 6.0 N2 1.69100 V2 54.8 r4 -32.719 d4 1.4 N3 1.59270 V3 35.6 r5 -490.6 d5 variable r6 -5.7813 d6 3.3 N4 1.72825 V4 28.5 r7 -7.682 d7 0.2 r8 16.579 d8 2.5 N5 1.71300 V5 54.0 r9 -19.4325 d9 3.2 r10 -11.067 d10 1.5 N6 1.72825 V6 28.5 r11 11.577 d11 0.85 r12 15.839 d12 3.9 N7 1.62041 V7 60.13 r13 -15.839 Said variable air distance being: When f 17.5 d2 19.740 d5 5.0 When f 25.32 d 4.303, d 20.437
Claim 7
Dependent Claim
236 words
A two point focus variable magnification lens system which comprises three lens groups having respectively dispersive, collective and collective refraction powers arranged in order from the object side, the first lens group being fixed as a rule, the second lens group being movable so as to vary the magnification, and the third lens group being a fixed position relay lens, and which satisfies the following several dimensions: r: Radii of curvatures of the refraction surfaces in sequence d: Axial widths or aid distances of the lens components in sequence N: Refractive indices of the glasses of the lens components in sequence V: Abbe''s numbers of the same glasses as just above in sequence Focal length f 17.5mm (Object distance: s1 0.8 m) f 25.32mm (Object distance: s2 0.4 m) Variation ratio of magnification 1.45 Aperture ratio 1 : 2.8 r1 43.605 d1 1.5 N1 1.62004 V1 36.3 r2 25.3206 d2 variable r3 34.6907 d3 6.0 N2 1.69100 V2 54.8 r4 -32.719 d4 1.4 N3 1.59270 V3 35.6 r5 -490.6 d5 variable r6 -5.7813 d6 3.3 N4 1.72825 V4 28.5 r7 -7.682 d7 0.2 r8 16.579 d8 2.5 N5 1.71300 V5 54.0 r9 -19.4325 d9 3.2 r10 -11.067 d10 1.5 N6 1.72825 V6 28.5 r11 11.577 d11 0.85 r12 15.839 d12 3.9 N7 1.62041 V7 60.13 r13 -15.839 Said variable air distance being: When f 17.5 d2 19.740 d5 5.0 When f 25.32 d 4.303, d 20.437
Claim 8
Dependent Claim
116 words
A two point focus variable magnification lens system in which only the second lens group is movable and focussing on one object at one fixed distance from the lens system is performed when the second lens group is at its first position, and focussing on another object at a shorter fixed distance from the lens system when the second lens group is at its second position, the object being at the minimum focal length from the lens system when focussing at the longer fixed distance from the lens system, and the object being at the maximum focal length when the focussing is at the shorter fixed distance from the lens system, said lens systems satisfying equations
Claim 9
Dependent Claim
116 words
A two point focus variable magnification lens system in which only the second lens group is movable and focussing on one object at one fixed distance from the lens system is performed when the second lens group is at its first position, and focussing on another object at a shorter fixed distance from the lens system when the second lens group is at its second position, the object being at the minimum focal length from the lens system when focussing at the longer fixed distance from the lens system, and the object being at the maximum focal length when the focussing is at the shorter fixed distance from the lens system, said lens systems satisfying equations
Claim 10
Dependent Claim
68 words
The two point focus variable magnification lens system as set forth in claim 5, wherein the lens system comprises three lens groups having respectively dispersive, collective and collective refraction powers arranged in that order from the object side, the first lens group being fixed, the second lens group being movable so as to vary the magnification and the third lens group being a fixed position relay lens group.
Claim 11
Dependent Claim
138 words
A video-telephone system, comprising means for transmitting and receiving video-telephone images, a lens system for alternately focussing upon the head and shoulders of one subscriber and also alternately focussing upon documents closer to the lens system, said lens system including a first lens group and a second lens group and a third lens group arranged along an optical axis, the head and shoulders of a subscriber being anticipated to be a distance s1 from the front end of the lens system, the document being anticipated to be a distance s2 from the front end of the lens system, the lens system requiring a magnification zF for producing images to be transmitted of the head and shoulders of the subscriber, the lens system requiring a magnification F for transmitting images of the document, said lens system satisfying the equations
Claim 12
Dependent Claim
138 words
A video-telephone system, comprising means for transmitting and receiving video-telephone images, a lens system for alternately focussing upon the head and shoulders of one subscriber and also alternately focussing upon documents closer to the lens system, said lens system including a first lens group and a second lens group and a third lens group arranged along an optical axis, the head and shoulders of a subscriber being anticipated to be a distance s1 from the front end of the lens system, the document being anticipated to be a distance s2 from the front end of the lens system, the lens system requiring a magnification zF for producing images to be transmitted of the head and shoulders of the subscriber, the lens system requiring a magnification F for transmitting images of the document, said lens system satisfying the equations
Claim 13
Dependent Claim
72 words
An apparatus as in claim 7, wherein said first and second and third lens groups have respective dispersive, collective, and collective refraction powers arranged in that order from the object, said third lens group being a fixed position relay lens group, said first and third lens groups being substantially fixed relative to each other, said second lens group being movable only to between two positions defining the focal lengths zF and F.
References Cited (Backward Citations)
GB1067428A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-28 | 1977-07-30 | 1978-01-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-28 | 1981-07-30 | 1982-01-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-28 | 1985-07-30 | 1986-01-29 | $7700.00 | Window Closed / Lapsed |