Heat-responsive temperature control device

Claim 2

A heat-responsive temperature control device comprising a. a series circuit connected across the terminals of an AC power source, said series circuit including a heaterconstituting resistance load, a plurality of diodes and a thyristor, b. gate signal generating means connected to the gate of said thyristor, c. a charge-and-discharge circuit including a capacitor having one end connected to the anode of said thyristor and a resistor having one end connected to the cathode of said thyristor, d. lead means connecting the juncture between the other ends of said capacitor and said resistor to one terminal of said power source, e. a reverse current blocking diode connected between the other terminal of said power source and the terminal of said capacitor to which the anode of the thyristor is connected, said blocking diode having a polarity opposite to that of said plurality of diodes, whereby said thyristor is triggered at its gate during the negative half cycle of said power source to be rendered and maintained in its conductive state until the subsequent positive half cycle by charge stored in said capacitor.

Claim 3

The device according to claim 1, in which said heater-constituting resistance load is composed of heating wires mounted in an insulating material which is fusible at a temperature above a predetermined value, and said gate signal generating means includes a series circuit composed of a variable resistor, a couple of conductors interposing a thermistor therebetween, a pulse generator and the primary winding of a pulse transformer, said series circuit being connected across the terminals of said power source, the secondary winding of said pulse transformer being connected between the gate and the cathode of said thyristor.

Claim 4

The device according to claim 1, in which said gate signal generating means includes a series circuit composed of a variable resistor, one of a couple of conductors interposing a thermistor therebetween, a pulse generator and the primary winding of a pulse transformer, said series circuit being connected across the terminals of an AC source, the secondary winding of said pulse transformer being connected between the Gate and the cathode of said thyristor.

Claim 5

A device according to claim 3 wherein the series circuit comprising said gate signal generating means further includes the other of said couple of conductors having the thermistor interposed therebetween.

Claim 6

The device according to claim 4, in which said heating member is composed of a couple of heating wires mounted in an insulating material which is fusible at a temperature above a predetermined value, one of said couple of heating wires being connected in series with one of said plurality of diodes series-connected with said thyristor to said one terminal of the power source, and the other being connected in series with another of said plurality of diodes series-connected to said thyristor to the other terminal of said power source.

Claim 7

A heat-responsive temperature control device comprising a. a thermistor layer interposed between a pair of conductors which serve as a heater and a signal wire respectively, b. a first series circuit composed of one of said pair of conductors, first and second diodes, and a thyristor connected across an AC power source, c. gate signal generating means including a second series circuit composed of a temperature-adjusting variable resistor, the other of said pair of conductors, a pulse generator and the primary winding of a pulse transformer connected across said power source, the secondary winding of said pulse transformer being connected between the gate and the cathode of said thyristor, d. a third diode connected across the one of said paired conductors constituting the heater in opposite polarity with said first and second diodes, e. a fourth diode connected in parallel with a series circuit composed of said thyristor and said second diode in opposite polarity therewith, f. a charge-and-discharge circuit composed of a series-connected capacitor and a resistor connected between the anode and the cathode of said thyristor, g. and lead means connecting the juncture between said capacitor and said resistor of the charge and discharge circuit to a terminal of said power source.

Claim 8

A heat-responsive temperature control device comprising a. a thermistor layer interposed between a pair of conductors which serve as a heater and a signal wire respectively, b. a first series circuit composed of one of said pair of conductors, first and second diodes, and a thyristor connected across an AC power source, c. gate signal generating means including a second series circuit composed of a temperature-adjusting variable resistor, the other of said pair of conductors, a pulse generator and the primary winding of a pulse transformer connected across said power source, the secondary winding of said pulse transformer being connected between the gate and the cathode of said thyristor, d. a third diode connected across the one of said paired conductors constituting the heater in opposite polarity with said first and second diodes, e. a fourth diode connected in parallel with a series circuit composed of said thyristor and said second diode in opposite polarity therewith, f. a charge-and-discharge circuit composed of a series-connected capacitor and a resistor connected between the anode and the cathode of said thyristor, g. and lead means connecting the juncture between said capacitor and said resistor of the charge and discharge circuit to a terminal of said power source.