Proportioning temperature control apparatus

Claim 2

A proportional temperature control apparatus for generating at an output heating or cooling producing signals to be cyclically intermittently applied over a range of temperatures so the proportion of each cycle a heating or cooling producing signal is present is a maximum at one end of said temperature range and progressively decreases to a minimum near zero at the other end of the temperature range, said apparatus comprising: manually operable temperature set point means for selecting the midpoint of the range of temperatures over which the proportional temperature control is to take place, temperature measuring means responsive to the temperature of the environment to be heated or cooled, a control circuit responsive to said manually operable temperature set point means and said temperature measuring means for generating said cyclically applied signals at said output within the selected temperature range, said control circuit including bandwidth and rate control means for simultaneously adjusting both the number of degrees included within said range of temperatures over which the proportional control is effected, and the rate at which said heating or cooling signals are cyclically applied to said output at corresponding points within the selected range of temperatures increasing with the number of degrees within the temperatures range over which proportional control is effected.

Claim 3

In proportional temperature control apparatus including an output at which heating or cooling producing signals are to be cyclically applied so the proportion of each cycle a heating or cooling producing signal is present is a maximum at one end of said temperature range and progressively decreases to a minimum near zero at the other end of the temperature range, manually operable temperature set point means for selecting the midpoint of the range of temperatures over which the proportional temperature control is to take place, and temperature measuring means responsive to the temperature of the environment to be heated or cooled, the improvement comprising: a differential input signal responsive circuit which generates a heating or cooling producing signal at the output of said apparatus when an input signal fed thereto reaches a first level and continues to generate said heating or cooling producing signal at said output until said input signal reverses direction and reaches a second signal level, whereupon said heating and cooling producing signal disappears until the resultant input signal again reaches said first level; first voltage generating means responsive to said temperature measuring means and said manually operable temperature set point means for providing a first input voltage component which progressively varies between first and second voltage levels as the temperature of said environment varies between the limits of said temperature range over which proportional control is to be effected; second voltage generating means which provides a second input voltage component which is mixed or added to said first input voltage component; signal feeding means for feeding a signal to said input of said differential input signal resPonsive circuit which is a function of the added or mixed voltage components; said second voltage generating means including a capacitor across which said second input voltage component is developed, and a charge circuit for the capacitor including means for selectively providing first and second DC capacitor charging voltages having values spaced apart a number of voltage units substantially greater than the variation of said second voltage input component, and means responsive to the presence of heating or cooling signals in the output of said temperature control apparatus for causing the capacitor to charge toward one of said DC voltages to bring the voltage across the capacitor to a value which provides a resultant signal at said second level at the input of said differential input signal responsive circuit which causes the heating or cooling signals to disappear from said output, and responsive to the absence of heating or cooling signals in the output of said temperature control apparatus for causing the capacitor to charge toward the other of said DC voltages to bring the voltage across the capacitor to a value which provides a resultant signal at first level at the input of said differential input signal responsive circuit to reestablish said heating or cooling signals at the output of said temperature control apparatus.

Claim 4

In proportional temperature control apparatus including an output at which heating or cooling producing signals are to be cyclically applied so the proportion of each cycle a heating or cooling producing signal is present is a maximum at one end of said temperature range and progressively decreases to a minimum near zero at the other end of the temperature range, manually operable temperature set point means for selecting the midpoint of the range of temperatures over which the proportional temperature control is to take place, and temperature measuring means responsive to the temperature of the environment to be heated or cooled, the improvement comprising: a differential input signal responsive circuit which generates a heating or cooling producing signal at the output of said apparatus when an input signal fed thereto reaches a first level and continues to generate said heating or cooling producing signal at said output until said input signal reverses direction and reaches a second signal level, whereupon said heating and cooling producing signal disappears until the resultant input signal again reaches said first level; first voltage generating means responsive to said temperature measuring means and said manually operable temperature set point means for providing a first input voltage component which progressively varies between first and second voltage levels as the temperature of said environment varies between the limits of said temperature range over which proportional control is to be effected; second voltage generating means which provides a second input voltage component which is mixed or added to said first input voltage component; signal feeding means for feeding a signal to said input of said differential input signal resPonsive circuit which is a function of the added or mixed voltage components; said second voltage generating means including a capacitor across which said second input voltage component is developed, and a charge circuit for the capacitor including means for selectively providing first and second DC capacitor charging voltages having values spaced apart a number of voltage units substantially greater than the variation of said second voltage input component, and means responsive to the presence of heating or cooling signals in the output of said temperature control apparatus for causing the capacitor to charge toward one of said DC voltages to bring the voltage across the capacitor to a value which provides a resultant signal at said second level at the input of said differential input signal responsive circuit which causes the heating or cooling signals to disappear from said output, and responsive to the absence of heating or cooling signals in the output of said temperature control apparatus for causing the capacitor to charge toward the other of said DC voltages to bring the voltage across the capacitor to a value which provides a resultant signal at first level at the input of said differential input signal responsive circuit to reestablish said heating or cooling signals at the output of said temperature control apparatus.

Claim 5

The proportional temperature control apparatus of claim 2 wherein the time constant of said capacitor charge circuit over the various temperatures involved within said temperature range remains substantially constant.

Claim 6

The proportional temperature control apparatus of claim 2 wherein said voltage charge circuit of said second voltage generating means including means for selectively varying the value of at least one of said first and second DC capacitor charging voltages.

Claim 7

The proportional temperature control apparatus of claim 2 wherein said means responsive to the presence or absence of the heating or cooling signals in the output of the apparatus includes a bridge circuit having opposite branches connected across a pair of voltage energizing input terminals, the capacitor and a charging resistance being connected across intermediate points of said branches constituting output terminals of the bridge circuit, and means for selectively varying the points of connection of said capacitor and charging resistance to at least one of said branches in accordance with the presence and absence of the heating or cooling signals in the output of said apparatus to provide said first and said second capacitor charging voltages.

Claim 8

The proportional control apparatus of claim 5 wherein one of said branches has a potentiometer with a wiper constituting one of said points of connection of said capacitor and charging resistance and the other point of connection thereof in said one branch being a point other than the potentiometer, wherein the variation of the position of the wiper on the potentiometer will progressively vary the magnitude of one of said capacitors charging voltages.

Claim 9

The proportional control apparatus of claim 2 wherein said means responsive to the presence and absence of the heating or cooling signals in the output of the apparatus includes a voltage divider circuit having at least three series connected resistor means extending between a pair of DC energizing voltage input terminals, said capacitor having one plate coupled to a point in the voltage divider circuit remote from adjacent ones of said resistor means, and switch means respectively coupling the other plate of said capacitor through a charging resistor means to the remote ends of said adjacent resistor means when the heating or cooling signals are respectively present and absent in the output of the proportional control apparatus.

Claim 10

The proportional temperature control apparatus of claim 7 wherein said one plate of said capacitor is coupled to the juncture of said adjacent resistor means through at least two series connected coupling resistor meAns of very high value relative to said capacitor charging resistor means so the latter is insignificant relative thereto, and said means for feeding a signal to said differential input signal responsive circuit including means responsive to the voltage across the one of said series connected coupling resistor means remote from said one plate of said capacitor.

Claim 11

The proportional temperature control apparatus of claim 8 provided with automatic offset eliminating means comprising a second capacitor and a second charging resistor means connected in series across the first-mentioned capacitor and its charging resistor means, the time constant of the second capacitor and its charging resistor means being extremely long relative to the time constant of the first-mentioned capacitor and its charging resistor means, and means for coupling the voltage across said second capacitor to the terminal of said one coupling resistor means remote from said first-mentioned capacitor, whereby ultimately the voltage across said one coupling resistor means drops substantially to zero.

Claim 12

The proportional temperature control apparatus of claim 8 wherein said first voltage generating means comprises a DC bridge circuit having a pair of DC voltage input terminals and a pair of resistance-containing branches extending between said voltage input terminals, there being associated with at least one of said branches variable responsive means which produces a variation in the voltage between a point associated with said one branch constituting an output terminal of the bridge circuit and a point in common between said branches, said manually operable temperature set point means including means for varying the point of connection of a second output terminal for the bridge to said other branch; second and third capacitors respectively coupled between said bridge output terminals and said common point; and said means for feeding a signal to the input of said differential input signal responsive circuit includes means for coupling the output across said one coupling resistor means of said voltage divider circuit respectively across the terminals of said second and third capacitors remote from said common point, said voltage divider and bridge circuits sharing a common DC voltage source, a fourth capacitor having one plate connected to said common point, switch means for connecting the other plate of said fourth capacitor alternately and cyclically to the plate of said second and third capacitors remote from said common point, and means for coupling the output of said fourth capacitor to the input of said differential input responsive circuit.

Claim 13

The proportional temperature control apparatus of claim 2 wherein said differential level signal output circuit responds to a chopped signal so said signal levels represent the envelope of the chopped signals, said first voltage generating means comprises a DC bridge circuit having a pair of DC voltage input terminals and a pair of resistance-containing branches extending between said voltage input terminals, there being associated with one of said branches said temperature measuring means which produces a variation in the voltage with temperature between a point associated with said one branch constituting an output terminal of the bridge circuit and a point in common between said branches, said manually operable temperature set point means including means for varying the point of connection of a second output terminal for the bridge to said other branch; second and third capacitors respectively coupled between said bridge output terminals and said common point; and said means for feeding a signal to the input of said differential input signal responsive circuit includes means for coupling a voltage following that across said first mentioned capacitor across the terminals of said second and third capacitors remote from said common point, a fourth capacitor having one plate connected to said common point, switch means for connecting the oTher plate of said fourth capacitor alternately and cyclically to the plate of said second and third capacitors remote from said common point, and means for coupling the output of said fourth capacitor to the input of said differential input responsive circuit.

Claim 14

The proportional temperature control apparatus of claim 2 wherein there is provided offset eliminating means comprising means for progressively reducing said second input voltage component to zero over a prolonged period.

Claim 15

In proportional temperature control apparatus including an output at which heating or cooling producing signals are to be cyclically applied so the proportion of each cycle a heating or cooling producing signal is present is a maximum at one end of said temperature range and progressively decreases to a minimum near zero at the other end of the temperature range, manually operable temperature set point means for selecting the midpoint of the range of temperatures over which the proportional temperature control is to take place, and temperature measuring means responsive to the temperature of the environment to be heated or cooled, the improvement comprising: a differential input signal responsive circuit which generates a heating or cooling producing output signal when a resultant input voltage Er reaches a first level V1 and continues to generate a heating or cooling producing output signal until Er changes direction and reaches a second voltage level V2, whereupon said heating or cooling producing signal disappears until Er again reaches V1; first signal input generating means responsive to said temperature measuring means and said manually operable temperature set point means for providing a first input voltage component ei which progressively varies between a third and fourth level Vp1 and Vp2 as the temperature of said environment varies between the limits of said temperature range over which proportional control is effected; and second voltage input generating means which provides a second input voltage component ei'' coupled in additive relationship with said first input voltage component ei to the input of said differential input voltage responsive section, said second voltage input generating means including a capacitor across which said second input voltage component ei is generated, when the temperature of said environment is at one end of said temperature range the variation in the capacitor voltage to make Er vary between V1 and V2 being Vc1 and Vc1'' respectively to initiate and terminate said heating or cooling input signal, and when the temperature of said environment is at the other end of said temperature range the variation in capacitor voltage to make Er vary between V1 and V2 being Vc2 and Vc2'' respectively to initiate and terminate said heating or cooling output signal, means responsive to the presence of a heating or cooling signal in the output of the apparatus for applying to said capacitor through a charging resistance a voltage V3 which is at or near the value Vc1'' so it will take a relatively long time for the charge on the capacitor to reach the value Vc1'' relative to the time it takes to reach the value Vc1 when the temperature of the environment is at or near one end of said temperature range, and means responsive to the absence of a heating or cooling signal in the output of the apparatus for applying to said capacitor through a charging resistance a voltage V4 which is at or near the value Vc2 so it will take a relatively long time for the charge on the capacitor to reach the value Vc2 relative to the time it takes to reach the value Vc2'' when the temperature of the environment is at or near the other end of said temperature range.

Claim 16

In proportional temperature control apparatus including an output at which heating or cooling producing signals are to be cyclically applied so the proportion of each cycle a heating or cooling producing signal is present is a maximum at one end of said temperature range and progressively decreases to a minimum near zero at the other end of the temperature range, manually operable temperature set point means for selecting the midpoint of the range of temperatures over which the proportional temperature control is to take place, and temperature measuring means responsive to the temperature of the environment to be heated or cooled, the improvement comprising: a differential input signal responsive circuit which generates a heating or cooling producing output signal when a resultant input voltage Er reaches a first level V1 and continues to generate a heating or cooling producing output signal until Er changes direction and reaches a second voltage level V2, whereupon said heating or cooling producing signal disappears until Er again reaches V1; first signal input generating means responsive to said temperature measuring means and said manually operable temperature set point means for providing a first input voltage component ei which progressively varies between a third and fourth level Vp1 and Vp2 as the temperature of said environment varies between the limits of said temperature range over which proportional control is effected; and second voltage input generating means which provides a second input voltage component ei'' coupled in additive relationship with said first input voltage component ei to the input of said differential input voltage responsive section, said second voltage input generating means including a capacitor across which said second input voltage component ei is generated, when the temperature of said environment is at one end of said temperature range the variation in the capacitor voltage to make Er vary between V1 and V2 being Vc1 and Vc1'' respectively to initiate and terminate said heating or cooling input signal, and when the temperature of said environment is at the other end of said temperature range the variation in capacitor voltage to make Er vary between V1 and V2 being Vc2 and Vc2'' respectively to initiate and terminate said heating or cooling output signal, means responsive to the presence of a heating or cooling signal in the output of the apparatus for applying to said capacitor through a charging resistance a voltage V3 which is at or near the value Vc1'' so it will take a relatively long time for the charge on the capacitor to reach the value Vc1'' relative to the time it takes to reach the value Vc1 when the temperature of the environment is at or near one end of said temperature range, and means responsive to the absence of a heating or cooling signal in the output of the apparatus for applying to said capacitor through a charging resistance a voltage V4 which is at or near the value Vc2 so it will take a relatively long time for the charge on the capacitor to reach the value Vc2 relative to the time it takes to reach the value Vc2'' when the temperature of the environment is at or near the other end of said temperature range.

Claim 17

The proportional temperature control apparatus of claim 13 wherein the number of voltage units between said voltage levels V1 and V2 is a fraction of the number of voltage units between the voltages V3 and V4.

Claim 18

The proportional temperature control apparatus of claim 13 wherein said charging resistance for the capacitor remains substantially constant.

Claim 19

The proportional temperature control apparatus of claim 13 wherein there is provided means for selectively varying at least one of the voltages V3 and V4 effectively simultaneously to vary the number of degrees in said temperature range over which proportional control is effected and the period between the successive or cyclic appearance of the heating or cooling signals at the output of said apparatus, said period increasing with the reduction in the number of degrees in said temperature range for any given relative position within the range.

Claim 20

The proportional temperature control apparatus of claim 13 wherein said means responsive to the presence and absence of the heating or cooling signals in the output of the apparatus including a bridge circuit with the capacitor and said charging resistance being connected across the output of the bridge circuit, and means for varying the relative values of the resistances in at least two arms of the bridge circuit in accordance with the presence and absence of the heating or cooling signals in the output of said apparatus to produce said voltages V3 and V4.

Claim 21

The proportional temperature control apparatus of claim 2 wherein said differential level signal output circuit responds to a chopped signal so said signal levels represent the envelope of the chopped signals, said first voltage generating means includes a bridge having a pair of energizing voltage input terminals and a pair of resistance containing branches extending between said energizing voltage input terminals, there being associated with at least one of said branches said temperature measuring means which produces a variation in the voltage between a point associated with said one branch and constituting an output terminal of the bridge circuit and a point in common with said branches, said manually operable set point means being associated with the other of said branches to produce a variation in the voltage between a point associated with the other branch and constituting another output terminal of the bridge circuit and said common point, and a bridge output circuit connected between said bridge output terminals which includes the voltage output of said second voltage generating means applied between a voltage addition point in said output circuit and said common point so a voltage is provided at the voltage addition point which is a function of the sum of the voltage at one of said bridge output terminals and the output of said second voltage generating means, and said bridge output circuit including a chopper circuit comprising a pair of switch means in series between said voltage addition point and the other bridge output terminal, a capacitor coupled between the juncture of said switch means and said common point, and means for alternately rendering said switch means conductive and nonconductive at the desired chopping rate for alternately coupling said capacitor between said output terminals of the bridge circuit, the time constant of the circuit including said capacitor being such that the capacitor charges to the applied voltage during the conduction period of the associated switch means, and means for coupling the voltage variations on said capacitor to the input of said differential level signal output circuit.

Claim 22

The bridge circuit of claim 18 wherein said switch means are a pair of field effect transistors with the corresponding load terminals thereof respectively connected between said capacitor and said voltage addition point and the latter said other bridge input terminal, said means for rendering said switch means alternately conductive including means for feeding signals to the gate terminals of said field effect transistors for alternately rendering the same conductive and nonconductive.