Regulator circuit for photographic illumination
First Claim
1. A circuit for regulating an alternating input voltage source of the type subject to relatively wide variations in amplitude and in frequency to provide an energizing current to a load at a select power level, said regulating circuit comprising:
- a pair of input terminals for connection to the source of alternating input voltage;
a pair of output terminals for connection to a load;
first switch means in series connection electrically with said output load terminals between said input terminals for switching between a nonconductive state and a conductive state in which said switch means carries current during a portion of each half-cycle of the alternating input voltage;
control means connected with said switch means and actuatable for selectively switching said switch means from its said nonconductive state is its said conductive state;
timing means for actuating said control means to switch said switch means from its said nonconductive state to its said conductive state ater an adjustable time interval within each half-cycle of alternating input voltage wherein said timing means includes a timing capacitor and means for charging said timing capacitor;
first regulating means of a feed-forward type in electrical connection with said timing means and with said control means for adjusting said time interval in response to variations in the input voltage wherein said first regulating means includes second switch means connected with said timing capacitor for actuating said control means only in response to a voltage arising across said timing capacitor having a select value relative to the amplitude of the input voltage; and
second regulating means of the feedback type in electrical connection with said timing means and with the voltage developed across said output terminals for adjusting said time interval in response to variations in the mean square of the voltage developed across said output terminals.
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Accused Products
Abstract
An electrical regulator for operating a photographic illuminating lamp provides two controls on the triggering of a phase-controlled power switch. One control employs a differential switch in a feed-forward loop that adjusts the potential at which a timing capacitor triggers the power switch. The other control is a feedback loop which controls the rate at which the timing capacitor is charged. The regulator combines the feed-forward and feedback controls to regulate the mean square of the lamp voltage for a wide range of input voltage amplitudes and frequency.
46 Citations
9 Claims
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1. A circuit for regulating an alternating input voltage source of the type subject to relatively wide variations in amplitude and in frequency to provide an energizing current to a load at a select power level, said regulating circuit comprising:
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a pair of input terminals for connection to the source of alternating input voltage; a pair of output terminals for connection to a load; first switch means in series connection electrically with said output load terminals between said input terminals for switching between a nonconductive state and a conductive state in which said switch means carries current during a portion of each half-cycle of the alternating input voltage; control means connected with said switch means and actuatable for selectively switching said switch means from its said nonconductive state is its said conductive state; timing means for actuating said control means to switch said switch means from its said nonconductive state to its said conductive state ater an adjustable time interval within each half-cycle of alternating input voltage wherein said timing means includes a timing capacitor and means for charging said timing capacitor; first regulating means of a feed-forward type in electrical connection with said timing means and with said control means for adjusting said time interval in response to variations in the input voltage wherein said first regulating means includes second switch means connected with said timing capacitor for actuating said control means only in response to a voltage arising across said timing capacitor having a select value relative to the amplitude of the input voltage; and second regulating means of the feedback type in electrical connection with said timing means and with the voltage developed across said output terminals for adjusting said time interval in response to variations in the mean square of the voltage developed across said output terminals. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A lamp regulator circuit for regulating an alternating input voltage source of the type subject to relatively wide variations in amplitude and in frequency to provide an energizing current to a lamp at a select power level, said regulator circuit comprising:
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a pair of input terminals for connection to the source of the alternating input voltage; a pair of output terminals for connection to a lamp; a semiconductor current-carrying switch means in series electrically with said output terminals between said input terminals, for switching between a nonconductive state and a first conductive state to carry current in a first conduction direction during the first half-cycle of the alternating input voltage, and a second conductive state to carry current in a second conduction direction during a second half-cycle of an alternating input voltage; rectifier means in parallel electrical connection with said switch means for producing a direct voltage in response to the alternating input voltage; trigger means for initiating conduction of said switch means; a timing capacitor; means for charging said timing capacitor from a substantially fixed voltage developed from said rectifier direct voltage; differential semiconductor switch means having a normally-open conduction path in series between said timing capacitor and said trigger means and having a gate element for initiating conduction therein connected to receive a voltage proportional to the amplitude of the alternating input voltage; a feedback detector in electrical connection with the voltage across said output terminals for developing in response thereto a feedback signal; and means for controlling the rate at which said capacitor-charging means charges said timing capacitor in resonse to said feedback signal, wherein said differential switch means controls the timing capacitor voltage at which said trigger means initiates switch means conduction in response to the amplitude of said input voltage, and said feedback detector and control means regulate the rate of capacitor charging in response to the voltage developed at said load terminals. - View Dependent Claims (9)
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Specification