US3625607A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic focusing camera
Assignee: Individual
•
Filing: 1969-05-22
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Granted: 1971-12-07
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Expires: 1989-05-22
Abstract
Abstract A preferred embodiment of an automatic focusing device for a camera system which gives the necessary magnification. It includes a pair of servo driven self-nulling bridge circuits. The physical position of the lens, image source and image plane is encoded by slide rheostats.
Inventors
- 👤 Frank R Bravenec
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 20:33
CPC Classifications
G; G03; G03B; G03B27/00; G03B27/32; G03B27/34
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
193 words
An apparatus for positioning a lens system image source and a photographic medium to obtain a sharp image and a desired image magnification, comprising: a. a first bridge circuit; b. a second bridge circuit; c. sliding resistive position indicator means adapted to be connected to and positioned by a lens system, image source and photographic medium of an associated equipment, said means forming signals indicative of the positions of the connected equipment; d. circuit means connected to said indicator means and to said bridge circuits such that at least one leg of each bridge circuit is comprised at least partially of said indicator means; e. said first bridge circuit implementing the equation 1/F 1/V+1/u Where: F-Focal length of the lens system u-Distance to the image source V-Distance to the photographic medium; f. said second bridge circuit implementing the equation M h''/h Where: M-magnification ratio L''-Size of the image at the photographic medium h-Size of the image at the image source; and, g. motive means adapted to move at least one of the image image source, photographic medium, or lens system in responSe to the inbalance of at least one of said bridge circuits.
Claim 2
Independent Claim
193 words
An apparatus for positioning a lens system image source and a photographic medium to obtain a sharp image and a desired image magnification, comprising: a. a first bridge circuit; b. a second bridge circuit; c. sliding resistive position indicator means adapted to be connected to and positioned by a lens system, image source and photographic medium of an associated equipment, said means forming signals indicative of the positions of the connected equipment; d. circuit means connected to said indicator means and to said bridge circuits such that at least one leg of each bridge circuit is comprised at least partially of said indicator means; e. said first bridge circuit implementing the equation 1/F 1/V+1/u Where: F-Focal length of the lens system u-Distance to the image source V-Distance to the photographic medium; f. said second bridge circuit implementing the equation M h''/h Where: M-magnification ratio L''-Size of the image at the photographic medium h-Size of the image at the image source; and, g. motive means adapted to move at least one of the image image source, photographic medium, or lens system in responSe to the inbalance of at least one of said bridge circuits.
Claim 3
Dependent Claim
63 words
The invention of claim 1 including a second motive means adapted to be connected to one of the remaining of the image source, photographic medium, or lens system, and wherein said first bridge circuit is connected on, and on inbalance thereof, drives said first motive means, and said second bridge circuit is connected to said second motive means and drives it on inbalance.
Claim 4
Dependent Claim
32 words
The invention of claim 1 wherein said first bridge circuit has four legs, two of which are standard impedance values and two of which are determined by said sliding resistive indicator means.
Claim 5
Dependent Claim
66 words
The invention of claim 3 wherein one of said legs is determined by a length of measure of the associated equipment proportional to the focal length of the lens system thereof, and the other is given by the parallel combination of the two measures of length of the associated equipment which are the distances from the image source and the photographic medium to the lens system.
Claim 6
Dependent Claim
95 words
The invention of claim 1 wherein said second bridge circuit has four legs, one of which is a standard impedance, the second thereof being an adjustable potentiometer having a range of values, one of the values thereof corresponding to a predetermined magnification ratio and other values thereof corresponding to different magnification ratios, the third leg thereof corresponding to the distance from the image formed by the lens system of the associated equipment to the photographic medium thereof, and the last leg thereof corresponding to the focal length of the lens system of the associated equipment.
Claim 7
Dependent Claim
41 words
The invention of claim 1 wherein said sliding resistance position indicator means includes first and second linear slide wire resistors positioned along the associated equipment to indicate the position of the image source, the lens system, and the photographic medium thereof.
Claim 8
Dependent Claim
32 words
The invention of claim 6 wherein slidable contacts are carried on said indicator means for additionally indicating a distance corresponding to the focal length of the lens system of the associated equipment.
Claim 9
Dependent Claim
74 words
The invention of claim 1 including an elongate slide wire resistive circuit component being contacted by a plurality of contacts, one of said contacts being adapted to be moved by and indicative of the position of the image source, a second being adapted to be moved by and indicative of the position of the lens system, and a third being adapted to be moved by and indicative of the position of the photographic medium.
Claim 10
Dependent Claim
37 words
The invention of claim 8 wherein the three contacts are connected to define two portions of said resistive slide wire which are connected in parallel to one another and are thusly connected into said first bridge circuit.
Claim 11
Dependent Claim
51 words
The invention of claim 1 wherein said first bridge circuit is connected to a differential amplifier and any inbalance thereof forms an output signal at said differential amplifier, and including connection with said motive means which is mechanically connected to either the image source or photographic medium of the associated equipment.
Claim 12
Dependent Claim
73 words
The invention of claim 1 wherein said second bridge circuit is connected to the input of a differential amplifier and any inbalance thereacross is amplified and forms an output at said differential amplifier, and said differential amplifier is further connected to a second motive means which is adapted to be connected with the lens system of the associated equipment for manipulation thereof which respect to the image source or the photographic medium thereof.
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) | 1974-12-06 | 1975-06-07 | 1975-12-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-12-06 | 1979-06-07 | 1979-12-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-12-06 | 1983-06-07 | 1983-12-07 | $7700.00 | Window Closed / Lapsed |