Photoelectric load control system
First Claim
1. A photoelectric load control system for applying a.c. power to a street light as a function of ambient light level, comprising:
- electromagnetically-activated switching means for selectively applying a.c. power to a street light for turning the street light on and off;
a Schmitt trigger circuit having two states, a first state which actuates said switching means to turn on the street light, and a second state which actuates said switching means to turn off the street light;
said trigger circuit further including a suppression circuit for suppressing regenerative oscillations caused by the operation of said switching means;
means for biasing said trigger circuit into one of said states; and
a photoelectric cell for varying the bias on said trigger circuit to bias it into the other state in response to the ambient light level sensed by said photoelectric cell wherein said trigger circuit and said photoelectric cell are commonly interconnected to a bias point of said means for biasing.
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Accused Products
Abstract
A photoelectric load control system for applying a.c. power to a street light as a function of ambient light level includes switching means for selectively applying a.c. power to a street light for turning the street light on and off; a trigger circuit having two states, a first state which actuates the switching means to turn on the street light and a second state which actuates the switching means to turn off the street light; means for biasing the trigger circuit into one of the states; and photoelectric sensing means for varying the bias on the trigger circuit to drive it into the other state in response to the ambient light level sensed by the photoelectric sensing means.
56 Citations
13 Claims
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1. A photoelectric load control system for applying a.c. power to a street light as a function of ambient light level, comprising:
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electromagnetically-activated switching means for selectively applying a.c. power to a street light for turning the street light on and off; a Schmitt trigger circuit having two states, a first state which actuates said switching means to turn on the street light, and a second state which actuates said switching means to turn off the street light; said trigger circuit further including a suppression circuit for suppressing regenerative oscillations caused by the operation of said switching means; means for biasing said trigger circuit into one of said states; and a photoelectric cell for varying the bias on said trigger circuit to bias it into the other state in response to the ambient light level sensed by said photoelectric cell wherein said trigger circuit and said photoelectric cell are commonly interconnected to a bias point of said means for biasing. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A photoelectric load control system for applying a.c. power to a street light as a function of ambient light level, comprising:
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a d.c. electromagnetic relay for selectively applying the a.c. power to a street light for turning the street light on and off; a Schmitt trigger circuit having two states, a first state which actuates said relay to turn on the street light, and a second state which actuates said relay to turn off the street light; said trigger circuit further including a suppression capacitor for suppressing low frequency regenerative oscillations caused by the operation of said relay; means for biasing said trigger circuit into one of said states; and a photoelectric cell for varying the bias on said trigger circuit to bias it into the other state in response to the ambient light level sensed by said photoelectric cell wherein said trigger circuit and said photoelectric cell are commonly interconnected to a bias point of said means for biasing.
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13. A photoelectric load control system for applying a.c. power to a street light as a function of ambient light level, comprising:
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a d.c. electromagnetic relay for selectively applying the a.c. power to a street light for turning the street light on and off; a Schmitt trigger circuit having two states, a first state which actuates said relay to turn on the street light, and a second state which actuates said relay to turn off the street light; said trigger circuit further including a suppression capacitor for suppressing low frequency regenerative oscillations caused by the changing inductance of said relay during said selective application of a.c. power to the street light; means for biasing said trigger circuit into one of said states; and a photoelectric cell for varying the bias on said trigger circuit to bias it into the other state in response to the ambient light level sensed b said photoelectric cell wherein said trigger circuit ad said photoelectric cell are commonly interconnected to a bias point of said means for biasing.
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Specification