LIGHTING CONTROL DEVICE
First Claim
1. A control device for controlling the operation of a load comprising, in combination, electric current supply means, photosensitive variable resistance means connected across said electric current supply means, temperature sensitive variable resistance means connected in series with said photosensitive variable resistance means and operating in response to variations of current therethrough and in ambient temperature for producing varying levels of heat, and thermal switch means operating in response to the heat produced by said temperature sensitive variable resistance means for controlling the operation of the load, said temperature sensitive variable resistance means havinG a positive temperature co-efficient whereby its resistance increases with an increase in temperature and decreases with a decrease in temperature, so as to limit the heat produced thereby and to accelerate its production of heat under low ambient temperature conditions, said temperature sensitive variable resistance means being in thermal contact with said thermal switch means, and means for connecting said thermal switch means in series with the load and said electric current supply means, said thermal switch means comprising a pair of contacts which are normally closed when said temperature sensitive variable resistance means is in non-operative cool condition, and which are normally open when said temperature sensitive variable resistance means is in operative, heat-generating condition, surge suppressing resistor means connected in series with said photosensitive means and said temperature sensitive variable resistance means, and surge protective means connected across said photosensitive means and said temperature sensitive variable resistance means and in series with said surge suppressing resistor means.
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Abstract
Photoelectric control device for switching loads such as street lighting luminaires on and off in response to ambient light levels. The circuit includes a photoelectric cell and a positive temperature co-efficient resistor (PTCR) connected in series across the luminaire load and normally closed contacts of a thermal switch in series with the luminaire load operating in response to the heat level of the PTCR, which thereby serves to compensate for varying levels of ambient temperature.
26 Citations
1 Claim
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1. A control device for controlling the operation of a load comprising, in combination, electric current supply means, photosensitive variable resistance means connected across said electric current supply means, temperature sensitive variable resistance means connected in series with said photosensitive variable resistance means and operating in response to variations of current therethrough and in ambient temperature for producing varying levels of heat, and thermal switch means operating in response to the heat produced by said temperature sensitive variable resistance means for controlling the operation of the load, said temperature sensitive variable resistance means havinG a positive temperature co-efficient whereby its resistance increases with an increase in temperature and decreases with a decrease in temperature, so as to limit the heat produced thereby and to accelerate its production of heat under low ambient temperature conditions, said temperature sensitive variable resistance means being in thermal contact with said thermal switch means, and means for connecting said thermal switch means in series with the load and said electric current supply means, said thermal switch means comprising a pair of contacts which are normally closed when said temperature sensitive variable resistance means is in non-operative cool condition, and which are normally open when said temperature sensitive variable resistance means is in operative, heat-generating condition, surge suppressing resistor means connected in series with said photosensitive means and said temperature sensitive variable resistance means, and surge protective means connected across said photosensitive means and said temperature sensitive variable resistance means and in series with said surge suppressing resistor means.
Specification
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- Resources
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Current AssigneeCharlie B. Turner
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Original AssigneeCharlie B. Turner
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InventorsTurner, Charlie B.
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Primary Examiner(s)Stolwein, Walter
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Application NumberUS05/201,278Time in Patent Office504 DaysField of Search250/239,206,214 315/159 337/100,377,378US Class Current250/206CPC Class CodesH01H 47/24 having light-sensitive inputH05B 47/11 by determining the brightne...Y02B 20/40 Control techniques providin...
