Apparatus and method for controlling the power supplied to a load

Claim 2

A control circuit comprising: a load; a power source for said load; control means connected between said load and said power source, said control means being adapted to control the power supplied to said load and said control means comprising reference means adapted to generate a reference signal; monitoring means connected between said control means and said load, said monitoring means being adapted to generate a signal proportional to the instantaneous voltage supplied to said load; and a feedback circuit comprising a voltage squaring circuit connected between said monitoring means and said control means, said voltage squaring circuit being adapted to generate a signal proportional to the average value of the square of the signal generated by said monitoring means and to feed that signal to said control means, said control means being further adapted to compare the signal from said squaring circuit with said reference signal and to proportionally control the power supplied to said load in response to the difference between the reference signal and the signal from said squaring circuit.

Claim 3

The control circuit of claim 1 wherein said load is a resistive load.

Claim 4

The control circuit of claim 1 wherein said load is a resistive load, said power source is an AC power source, and said control means is adapted to control the power supplied to said load by controlling the portion of the AC cycle during which voltage is supplied to said load.

Claim 5

The controller of claim 1 wherein said voltage squaring circuit comprising: an input junction; an output junction; a resistance; and a plurality of voltage sensitive conductance elements adapted to begin conducting when the voltage across said conductance elements exceeds the conductance threshold of said conductance elements; said resistance and said conductance elements being disposed relative to one another and relative to said input junction and said output junction in such manner that the resistance between said input junction and said output junction changes in substantially discrete steps as the voltage applied to said input junction increases.

Claim 6

The voltage squaring circuit of claim 4 wherein said voltage sensitive conductance elements comprise a resistor and a dioDe connected in series and wherein the conductance threshold is the conductance threshold of said diode.

Claim 7

The voltage squaring circuit of claim 4 wherein: said resistance is connected directly between said input junction and said output junction; the first of said conductance elements is connected in parallel with said resistance; and each subsequent conductance element is connected in parallel with the resistor of the proceeding conductance element.

Claim 12

A control circuit comprising: a load; a power source for said load; control means connected between said load said power source, said control means being adapted to control the power supplied to said load and said control means comprising reference means adapted to generate a reference signal; voltage monitoring means connected between said control means and said load, said voltage monitoring means being adapted to generate a signal proportional to the instantaneous value of the voltage applied to said load; measuring means connected between said control means and said load, said measuring means being adapted to measure the property that said control circuit is adapted to control, to generate a measuring signal proportional to that property and to feed that measuring signal to said control means; and a voltage squaring circuit connected between said monitoring means and said control means, said voltage squaring circuit being adapted to generate a signal proportional to the average value of the square of the signal generated by said monitoring means, and to feed this signal to said control means, said control means being further adapted to add the measuring signal to the signal from said squaring circuit, to compare the resultant signal with the reference signal and to proportionally control the power supplied to said load in response to the difference between the resultant signal and said reference signal.

Claim 13

A control circuit comprising: a load; a power source for said load; control means connected between said load said power source, said control means being adapted to control the power supplied to said load and said control means comprising reference means adapted to generate a reference signal; voltage monitoring means connected between said control means and said load, said voltage monitoring means being adapted to generate a signal proportional to the instantaneous value of the voltage applied to said load; measuring means connected between said control means and said load, said measuring means being adapted to measure the property that said control circuit is adapted to control, to generate a measuring signal proportional to that property and to feed that measuring signal to said control means; and a voltage squaring circuit connected between said monitoring means and said control means, said voltage squaring circuit being adapted to generate a signal proportional to the average value of the square of the signal generated by said monitoring means, and to feed this signal to said control means, said control means being further adapted to add the measuring signal to the signal from said squaring circuit, to compare the resultant signal with the reference signal and to proportionally control the power supplied to said load in response to the difference between the resultant signal and said reference signal.

Claim 14

The control circuit of claim 9 wherein said load is a resistive load.

Claim 15

The control circuit of claim 9 wherein said load is a resistive load, said power source is an AC power source, and said control means is adapted to control the power supplied to said load by controlling the portion of the AC cycle during which voltage is applied to said load.

Claim 16

A temperature controller comprising: a load adapted to provide heat to a sample; a power source for said load; control means connected between said load and said power source, said control means being adapted to control the power supplied to said load and said control means comprising reference means adapted to generate a reference signal; voltage monitoring means connected between said control means and said load, said voltage monitoring means being adapted to generate a signal proportional to the instantaneous value of the voltage applied to said load; temperature monitoring means connected beTween said control means and said load, said temperature monitoring means being adapted to generate a temperature signal proportional to the temperature monitored, and to feed that temperature signal to said control means; and voltage squaring circuit connected between said monitoring means and said control means, said voltage squaring circuit being adapted to generate a signal proportional to the average value of the square of the signal generated by said monitoring means, and to feed this signal to said control means, said control means being further adapted to add the temperature signal to the signal from said squaring circuit, to compare the resultant signal with said reference signal and to proportionally control the power supplied to said load in response to the difference between the resultant signal and said reference signal.

Claim 17

A temperature controller comprising: a load adapted to provide heat to a sample; a power source for said load; control means connected between said load and said power source, said control means being adapted to control the power supplied to said load and said control means comprising reference means adapted to generate a reference signal; voltage monitoring means connected between said control means and said load, said voltage monitoring means being adapted to generate a signal proportional to the instantaneous value of the voltage applied to said load; temperature monitoring means connected beTween said control means and said load, said temperature monitoring means being adapted to generate a temperature signal proportional to the temperature monitored, and to feed that temperature signal to said control means; and voltage squaring circuit connected between said monitoring means and said control means, said voltage squaring circuit being adapted to generate a signal proportional to the average value of the square of the signal generated by said monitoring means, and to feed this signal to said control means, said control means being further adapted to add the temperature signal to the signal from said squaring circuit, to compare the resultant signal with said reference signal and to proportionally control the power supplied to said load in response to the difference between the resultant signal and said reference signal.

Claim 18

The control circuit of claim 12 wherein said load is a resistive load.

Claim 19

The control circuit of claim 12 wherein said load is a resistive load, said power source is an AC power source, and said control means is adapted to control the power supplied to said load by controlling the portion of the AC cycle during which voltage is applied to said load.

Claim 20

The control circuit of claim 12 wherein said temperature monitoring means is adapted to monitor the temperature of the load.

Claim 21

The control circuit of claim 12 wherein said temperature monitoring means is adapted to monitor the temperature of the sample.

Claim 22

The controller of claim 12 wherein said voltage squaring circuit comprising: an input junction; an output junction; a resistance; and a plurality of voltage sensitive conductance elements adapted to begin conducting when the voltage across said conductance elements exceeds the conductance threshold of said conductance elements; said resistance and said conductance elements being disposed relative to one another and relative to said input junction and said output junction in such manner that the resistance between said input junction and said output junction changes in substantially discrete steps as the voltage applied to said input junction increases.

Claim 23

The voltage squaring circuit of claim 17 wherein said voltage sensitive conductance elements comprise a resistor and a diode connected in series and wherein the conductance threshold is the conductance threshold of said diode.

Claim 24

The voltage squaring circuit of claim 17 wherein: said resistance is connected directly between said input junction and said output junction; the first of said conductance elements is connected in parallel with said resistance; and each subsequent conductance element is connected in parallel with the resistor of the preceding conductance element.