US3611894A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic exposure control system
Assignee: Bell and Howell Co
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Filing: 1969-04-22
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Granted: 1971-10-12
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Expires: 1989-04-22
Abstract
Abstract This disclosure describes an automatic exposure control system for controlling the iris of a camera. Power is applied through a stabilizing voltage string and voltage dividers, as well as from unregulated batteries through collector resistors, to preamplifiers. A photocell circuit that senses the amount of light passing through the iris is connected to the inputs of the preamplifiers. Signal shapers are connected to the preamplifiers to provide fast exposure correction without overshoot. The outputs from the preamplifiers are connected through stabilizer amplifiers and power amplifiers to a motor which controls the opening and closing of the iris. The stabilizer amplifiers may also be connected through a feedback circuit to the photocell circuit so that sustained oscillations are created and either a balanced or an unbalanced duty cycle waveform is imposed upon the reversible DC motor. When the duty cycle waveform is balanced, the motor has moved the iris to its correct balance position. When the waveform is unbalanced, the motor shaft rotates and moves the connected iris in the appropriate direction.
Inventors
- 👤 Viktor Minneste Jr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 04:58
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/081; G03B7/085
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
152 words
An automatic exposure control system for controlling the opening of an iris comprising: a power supply; a diode string connected across the output terminal of said power supply; a first amplifier loop connected to said power supply to receive power from said power supply; a second amplifier loop connected to said power supply to receive power from said power supply; a feedback circuit connected between the inputs and the outputs of said first and second amplifier loops so as to be common to said first and second amplifier loops; a photocell circuit connected to said diode string and to said first and second amplifier loops, said photocell circuit including a photocell mounted to sense light passing through said iris; and, a reversible DC motor electrically connected to said first and second amplifier loops and having its shaft mechanically connected to said iris to control the size of the aperture of said iris.
Claim 2
Dependent Claim
152 words
An automatic exposure control system for controlling the opening of an iris comprising: a power supply; a diode string connected across the output terminal of said power supply; a first amplifier loop connected to said power supply to receive power from said power supply; a second amplifier loop connected to said power supply to receive power from said power supply; a feedback circuit connected between the inputs and the outputs of said first and second amplifier loops so as to be common to said first and second amplifier loops; a photocell circuit connected to said diode string and to said first and second amplifier loops, said photocell circuit including a photocell mounted to sense light passing through said iris; and, a reversible DC motor electrically connected to said first and second amplifier loops and having its shaft mechanically connected to said iris to control the size of the aperture of said iris.
Claim 3
Dependent Claim
45 words
An automatic exposure control system for controlling the opening of an iris as claimed in claim 1 wherein: said first amplifier loop includes a first preamplifier connected to said photocell circuit; and, said second amplifier loop includes a second preamplifier connected to said photocell circuit.
Claim 4
Dependent Claim
54 words
An automatic exposure control system for controlling the opening of an iris as claimed in claim 2 including: a first voltage divider, connected across a portion of said diode string, connected to said first preamplifier; and, a second voltage divider, connected across a different portion of said diode string, connected to said second preamplifier.
Claim 5
Dependent Claim
39 words
An automatic exposure control system for controlling the opening of an iris as claimed in claim 3 including: a first signal shaping network connected to said first preamplifier; and, a second signal shaping network connected to said second preamplifier.
Claim 6
Dependent Claim
95 words
An automatic exposure control system for controlling the opening of an iris as claimed in claim 4 wherein: said first amplifier loop includes a first amplifier having its input connected to the output of said first preamplifier and its output connected to one side of said feedback circuit; and, said second amplifier loop includes a second amplifier having its input connected to the output of said second preamplifier and its output connected to said one side of said feedback circuit, the other side of the feedback circuit being connected to said first and second preamplifiers.
Claim 7
Dependent Claim
75 words
An automatic exposure control system for controlling the opening of an iris as claimed in claim 5 including: a first power amplifier connected between the output of said first amplifier and one side of said DC motor; and, a second power amplifier connected between the output of said second amplifier and said one side of said DC motor, the other side of said DC motor being connected to the center tap of said power supply.
Claim 8
Dependent Claim
28 words
An automatic exposure control system for controlling the opening of an iris as claimed in claim 6 wherein said diode string is center tapped to said power supply.
Claim 9
Dependent Claim
37 words
An automatic exposure control system for controlling the opening of an iris as claimed in claim 7 including: a first stabilizing circuit connected to said first amplifier; and, a second stabilizing circuit connected to said second amplifier.
Claim 10
Dependent Claim
57 words
An automatic exposure control system for controlling the opening of an iris as claimed in claim 8 including: a switch mechanically connected to the shaft of said motor and electrically connected between said motor and the output of said second power amplifier, said switch being opened by said shaft when said iris is in a predetermined position.
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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) | 1974-10-11 | 1975-04-12 | 1975-10-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-10-11 | 1979-04-12 | 1979-10-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-10-11 | 1983-04-12 | 1983-10-12 | $7700.00 | Window Closed / Lapsed |