US4472743A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic diaphragm control device for a closed circuit television camera
Assignee: Pentax Precision Co Ltd
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Filing: 1982-04-02
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Granted: 1984-09-18
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Expires: 2002-04-02
Abstract
Abstract A diaphragm control for a video camera is disclosed and controls the camera diaphragm in response to the camera video output. The video output signal is inverted by an inverting amplifier and is selectively voltage doubled to vary the weight of the light portions of the signal with respect to its dark portions. The selectively voltage doubled signal is averaged to a D.C. voltage and is compared to a reference exposure voltage. The reference exposure voltage is automatically varied to compensate for level variations in the voltage doubled signal caused by the selective doubling.
Inventors
- 👤 Terumi Ogasawara
- 👤 Masayuki Arai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 15:15
CPC Classifications
H; H04; H04N; H04N23/00; H04N23/70; H04N23/75
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
170 words
A diaphragm control for a video camera producing a video output signal having bright signal portions and dark signal portions representative of bright and dark areas of the area monitored by said video camera, respectively, said control comprising: input means for receiving said video output signal; means for adjustably weighting said video output signal to vary the weight of said bright signal portions with respect to said dark signal portions, said means for adjustably weighting varying the average strength of said video output signal and producing a weighted signal therefrom; reference signal generator means for producing a reference signal representative of desired average signal strength, said reference signal being varied in strength in order to compensate for variations in the average strength of said weighted signal produced by said means for adjustably weighting; and comparator means for producing a comparator output corresponding to the difference between said reference signal and the average strength of said weighted signal, said comparator output being used as a control signal for the camera diaphragm.
Claim 2
Dependent Claim
170 words
A diaphragm control for a video camera producing a video output signal having bright signal portions and dark signal portions representative of bright and dark areas of the area monitored by said video camera, respectively, said control comprising: input means for receiving said video output signal; means for adjustably weighting said video output signal to vary the weight of said bright signal portions with respect to said dark signal portions, said means for adjustably weighting varying the average strength of said video output signal and producing a weighted signal therefrom; reference signal generator means for producing a reference signal representative of desired average signal strength, said reference signal being varied in strength in order to compensate for variations in the average strength of said weighted signal produced by said means for adjustably weighting; and comparator means for producing a comparator output corresponding to the difference between said reference signal and the average strength of said weighted signal, said comparator output being used as a control signal for the camera diaphragm.
Claim 3
Dependent Claim
13 words
The control of claim 1 wherein said input means includes an inverting amplifier.
Claim 4
Dependent Claim
30 words
The control of claim 2 wherein said means for adjustably weighting said video output signal includes a voltage doubling means for selectively doubling the voltage of said video output signal.
Claim 5
Dependent Claim
45 words
The control of claim 3 wherein said voltage doubling means includes a switch for selectively by-passing said voltage doubling means to place said control in an average light measuring mode, said control being in a peak light measurement mode when said switch is open circuited.
Claim 6
Dependent Claim
40 words
The control of claim 4 wherein said voltage doubling means includes a variable resistance to variably select the enablement of said voltage doubling means to switch said control between an average light measuring mode and a peak light measurement mode.
Claim 7
Dependent Claim
42 words
The control circuit of claim 5 wherein said voltage doubling means includes a capacitor which, when charged, enables operation of said voltage doubling means; said variable resistance being arranged in parallel with said capacitor to selectively prevent the charging of said capacitor.
Claim 8
Dependent Claim
33 words
The control circuit of claim 4 wherein said voltage doubling means includes a capacitor which, when charged, enables operation of said voltage doubling means; said switch, when actuated, preventing said capacitor from charging.
Claim 9
Dependent Claim
12 words
The control circuit of claim 7 wherein said switch is remotely controlled.
Claim 10
Dependent Claim
13 words
The control circuit of claim 6 wherein said variable resistance is remotely controlled.
Claim 11
Dependent Claim
177 words
A diaphragm control for a video camera producing a video output signal having bright signal portions and dark signal portions representative of bright and dark areas of the area monitored by said video camera, respectively, said control comprising: input means for receiving said video output signal; inverting amplifier means coupled to said input means for inverting said video output signal to form an inverted output signal; voltage doubling means for selectively doubling the voltage of said inverted output signal to produce voltage doubler output; means for averaging said voltage doubler output to produce a DC voltage control signal; means for comparing said DC voltage control signal with a reference voltage to generate a control signal for the camera diaphragm; said voltage doubling means varying the weight of said bright signal portions with respect to said dark signal portions of said inverted output signal and also varying the average strength of said video inverted output signal; and means for varying said reference voltage in order to compensate for variations in the average strength of said voltage doubler output.
Claim 12
Dependent Claim
177 words
A diaphragm control for a video camera producing a video output signal having bright signal portions and dark signal portions representative of bright and dark areas of the area monitored by said video camera, respectively, said control comprising: input means for receiving said video output signal; inverting amplifier means coupled to said input means for inverting said video output signal to form an inverted output signal; voltage doubling means for selectively doubling the voltage of said inverted output signal to produce voltage doubler output; means for averaging said voltage doubler output to produce a DC voltage control signal; means for comparing said DC voltage control signal with a reference voltage to generate a control signal for the camera diaphragm; said voltage doubling means varying the weight of said bright signal portions with respect to said dark signal portions of said inverted output signal and also varying the average strength of said video inverted output signal; and means for varying said reference voltage in order to compensate for variations in the average strength of said voltage doubler output.
Claim 13
Dependent Claim
45 words
The control of claim 10 wherein said voltage doubling means includes a switch for selectively by-passing said voltage doubling means to place said control in an average light measuring mode, said control being in a peak light measurement mode when said switch is open circuited.
Claim 14
Dependent Claim
33 words
The control circuit of claim 11 wherein said voltage doubling means includes a capacitor which, when charged, enables operation of said voltage doubling means; said switch, when actuated, preventing said capacitor from charging.
Claim 15
Dependent Claim
40 words
The control of claim 10 wherein said voltage doubling means includes a variable resistance to variably select the enablement of said voltage doubling means to switch said control between an average light measuring mode and a peak light measurement mode.
Claim 16
Dependent Claim
42 words
The control circuit of claim 13 wherein said voltage doubling means includes a capacitor which, when charged, enables operation of said voltage doubling means; said variable resistance being arranged in parallel with said capacitor to selectively prevent the charging of said capacitor.
Claim 17
Dependent Claim
12 words
The control circuit of claim 12 wherein said switch is remotely controlled.
Claim 18
Dependent Claim
13 words
The control circuit of claim 14 wherein said variable resistance is remotely controlled.
References Cited (Backward Citations)
US4050085A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-09-18 | 1988-03-19 | 1988-09-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-09-18 | 1992-03-19 | 1992-09-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-09-18 | 1996-03-19 | 1996-09-18 | $7700.00 | Window Closed / Lapsed |