Circuit for providing electrical energy to a heatable means
First Claim
1. A control circuit for variably applying time-wise A.C. power to a heating element comprising in combination:
- first and second input lines respectively connected to first and second terminals of an electrical power source and arranged with respect to said electrical power source such that when said first input line has a positive electrical potential, said second input line has a relatively negative electrical potential and alternatively when said first input line is a relatively negative electrical potential, second input line has a positive electrical potential;
first circuit means and second circuit means serially connected across said first and second input lines and having a first intermediate terminal located between said first circuit means and said second circuit means;
third circuit means and heating circuit means serially connected across said first and second input lines and having a second intermediate terminal located in between said third circuit means and said heating circuit means;
first switchable bidirectional electric current conducting means having first and second power lead means respectively connected to said first input line and to said second intermediate terminal, said first bidirectional electrical conducting means having gate means which respond to signals applied thereto to cause said first switchable bidirectional electrical current conducting means to conduct current from said second input line through said heating circuit means and therefrom in a first direction to said first input line through said first power lead means and alternatively in a second direction, through said second power lead means, to said second intermediate terminal and therefrom through said heating circuit means to said second input line;
storage circuitry means to develop a control voltage signal, including means to vary current transmitted for storage at said storage circuitry means, said storage circuitry means connected to said gate means and connected between said second intermediate terminal and said first input line to cause different amounts of current to flow through said first switchable bidirectional electrical current conducting means in said first direction and in said second direction in response to different voltage signals being developed at said signal storage means.
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Accused Products
Abstract
The present device includes a bridge circuit with a first intermediate terminal and a second intermediate terminal and with one leg of the bridge circuit being a heating element. Connected across the power lines of the bridge circuit is a main bidirectional switching circuit (having a gate element) which is turned on bidirectionally by control signals developed by an R-C circuit connected to the gate element. The resistors of the R-C circuit are for the most part integral components of two photoconductor isolator devices. These last mentioned resistors provide a low resistance after their associated LED'"'"'s are turned on and the one of them whose associated LED turns off at the zero crossover remains at a low resistance value for a period of time after its associated LED'"'"'s has turned off. In addition the present device includes a circuit to bypass the control signal which ordinarily would go to the main capacitor of the R-C circuit in the event that an overcurrent situation (e.g., a short circuit) occurs in the heating element circuit. The bridge circuit and the control signal circuitry (which is arranged across the bridge circuit) are designed so that the resistance of the heating element (which changes as the heating element heats up or cools off) acts as the sensing device to control or maintain the heat output at a predetermined temperature value.
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Citations
13 Claims
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1. A control circuit for variably applying time-wise A.C. power to a heating element comprising in combination:
- first and second input lines respectively connected to first and second terminals of an electrical power source and arranged with respect to said electrical power source such that when said first input line has a positive electrical potential, said second input line has a relatively negative electrical potential and alternatively when said first input line is a relatively negative electrical potential, second input line has a positive electrical potential;
first circuit means and second circuit means serially connected across said first and second input lines and having a first intermediate terminal located between said first circuit means and said second circuit means;
third circuit means and heating circuit means serially connected across said first and second input lines and having a second intermediate terminal located in between said third circuit means and said heating circuit means;
first switchable bidirectional electric current conducting means having first and second power lead means respectively connected to said first input line and to said second intermediate terminal, said first bidirectional electrical conducting means having gate means which respond to signals applied thereto to cause said first switchable bidirectional electrical current conducting means to conduct current from said second input line through said heating circuit means and therefrom in a first direction to said first input line through said first power lead means and alternatively in a second direction, through said second power lead means, to said second intermediate terminal and therefrom through said heating circuit means to said second input line;
storage circuitry means to develop a control voltage signal, including means to vary current transmitted for storage at said storage circuitry means, said storage circuitry means connected to said gate means and connected between said second intermediate terminal and said first input line to cause different amounts of current to flow through said first switchable bidirectional electrical current conducting means in said first direction and in said second direction in response to different voltage signals being developed at said signal storage means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
- first and second input lines respectively connected to first and second terminals of an electrical power source and arranged with respect to said electrical power source such that when said first input line has a positive electrical potential, said second input line has a relatively negative electrical potential and alternatively when said first input line is a relatively negative electrical potential, second input line has a positive electrical potential;
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10. A control circuit for variably applying time-wise A.C. power to a heating element comprising in combination:
- first and second input lines respectively connected to first and second terminals of an electrical power source from whence there is provided alternating current power;
a bridge circuit means connected across said first and second input lines, said bridge circuit means comprising at least first, second, and third resistance means which constitute respectively first, second, and third legs of said bridge circuit means and a heating circuit means constituting the fourth leg of said bridge circuit means, with a first intermediate terminal means being located between said first and second legs and a second intermediate terminal being located between said third and fourth legs;
first triac means series connected with a first resistor and with said last mentioned series connected circuit being connected between said first input line and said second intermediate terminal, said first triac having a gate means;
main capacitor means circuitry connected to said gate means of said triac and to said second intermediate terminal;
first photoconductor isolator means having a first light emitting diode and an associated resistor means and connected to said main capacitor to provide a triggering voltage signal to said main capacitor and therefore to said gate of said triac;
first silicon controlled rectifier means connected to said first light emitting diode and to said first and second intermediate terminals means whereby in response to a particular difference of potential between said first and second intermediate terminal means said silicon control rectifier means is turned on which causes said first light emitting diode to be turned on which in turn lowers the resistance of the resistor associated with said first light emitting diode to cause said triggering voltage signal to occur during each half cycle while said alternating current power is applied to said first and second input lines. - View Dependent Claims (11, 12, 13)
- first and second input lines respectively connected to first and second terminals of an electrical power source from whence there is provided alternating current power;
Specification