US3614391A

US3614391A - Control circuit for composite electronic modulator flexible heating element

Info

Publication number: US3614391A
Application number: US65868A
Authority: US
Inventors: Peter Lauck
Original assignee: JP Stevens and Co Inc
Current assignee: JP Stevens and Co Inc
Priority date: 1970-08-21
Filing date: 1970-08-21
Publication date: 1971-10-19
Anticipated expiration: 1988-10-19

Abstract

A composite electronic modulator flexible heating element control circuit, adapted to detachable juxtaposition with complemental outer and inner layers, as for example, undersheeting and a heating element insular, nonflammable layer and an outer decorative covering. In this particular circuit, an applied thermistor-sensor is adapted, upon a rise in preselected maximum temperature, to lowering its resistance to fire an NPN transistor to shut off an SCR load. The circuit is stable, sensitive and is particularly adapted to a nonflammable material, having an insular heat shield or ultrafrequency shield with the temperature responsive means being optionally either in the matrix of nonflammable material or in the control plug or control receptacle. It is adaptable to miniaturization by integrated circuit or equivalent means.

Description

United States Patent [72] Inventor Peter Lauck, III

Princeton, NJ.

[21] AppL No. 65,868

[22] Filed Aug. 21, 1970 [45] Patented Oct. 19, I971 [73] Assignee J. P. Stevens 8: Company, Inc.

New York, N.Y.

[54] CONTROL CIRCUIT FOR COMPOSITE ELECTRONIC MODULATOR FLEXIBLE HEATING ELEMENT 9 Claims, 2 Drawing Figs. v

[52] U.S.Cl 219/501 [5 1] Int. Cl r IIOSb 1/02 [50] Field of Search 219/501,

[56] References Cited UNITED STATES PATENTS 3,385,958 5/1968 Lauck 219/501 3,422,244 l/l969 Lauck 219/501 X 3,46l,273 8/1969 Dykcs 219/501 3,475,593 10/1969 Olofsson 219/501 3,478,532 11/] 969 Codtey et al 2l9/50l X Primary Examiner-Bernard A. Gilheany Assistant Examiner-F. E. Bell AttorneyJ. Gibson Semmes ABSTRACT: A composite electronic modulator flexible heating element control circuit, adapted to detachable juxtaposition with complemental outer and inner layers, as for example, undersheeting and a heating element insular, nonflammable layer and an outer decorative covering. In this particular circuit, an applied thermistor-sensor is adapted, upon a rise in preselected maximum temperature, to lowering its resistance to fire an NPN transistor to shut off an SCR load. The circuit is stable, sensitive and is particularly adapted to a nonflammable material, having an insular heat shield or ultrafrequency shield with the temperature responsive means being optionally either in the matrix of nonflammable material or in the control plug or control receptacle. It is adaptable to miniaturization by integrated circuit or equivalent means.

CONTROL CIRCUIT FOR COMPOSITE ELECTRONIC MODULATOR FLEXIBLE HEATING ELEMENT This invention is related to, but distinctive from the control circuit described in U.S. Pat. No. 3,385,958 issued May 28, I968 in the name of Peter Lauck, III, and U.S. Pat. No. 3,422,244 issued .Ian. 14, 1969 in the name of Peter Lauck, lll.

BACKGROUND OF THE INVENTION 1. Field of the Invention Whereas the invention is defined with reference to electronically controlled blankets, per se, it is obvious that its scope is such as to encompass any flexible heating system as for example, clothing, draperies, flexible partitions and the like.

2. Description of the Prior Art In addition to the aforementioned patents, the prior art comprises specifically U.S. Pat. No. 3,461,273, in the name of C. H. Dykes, issued Aug. 12, I969, entitled 'SOLID STATE CIRCUIT FOR CONTROLLING THE TEMPERATURE OF AN ELECTRIC APPLIANCE SUCH AS A BLANKET. Distinctive as to that and the aforementioned patents, is the specific means of biasing the transistor and the resultant effect thereof.

In the present instance the biasing and amplification of transistor means is effected by a series electrical configuration of temperature sensing means, and voltage control media connected directly to the base of a transistor on one side and the DC supply voltage on the other.

. In Dykes circuit (U.S. Pat. No. 3,461,273), however, specific claims are developed around resistive and capacitive switches and voltage divider means with resistive and capacitive legs contacted between a reference supply voltage on one hand, and ground on the other. Such divider means utilizes the variable legs and particularly the center tap between the reference voltage and ground as the connection to the base control electrode of a transistor. Dykes depends on capacitor and resistor 22 to interconnect the emitter of Q1 gate of his thyristor l2. Fundamentally, when his transistor 24 triggers on through its emitter, capacitor 20 and resistor 22 aid in providing a current path to the gate control electrode of the thyristor causing the latter to turn on.

In the opposite manner, the present system connects its transistor via its collector directly to and in common with the thyristor gate. Thus, it discharges its capacitor and when the transistor triggers it shunts current away from the thyristor gate through the transistor itself and a low resistive path, to ground. In so doing, it turns off the thyristor control, rather than turning it on" as in the Dykes emitter configuration. Thus, the two biasing arrangements, hookups and transistor functions difier radically.

SUMMARY OF THE INVENTION In the control of heating means for flexibleheating elements such. as electric blankets and the like, series voltage attenuation coupled with a connected capacitor to effect snap-on, snap-off control of the SCR or thyristor as opposed to normal parallel capcitive, resistive leg" bridge control systems, therefor. The present comprises cqmplemental series biasing of the applied voltage, sensor controlled, to turn on a transistor which in its turn produces a solid-off condition of the thyristor-switching unit control.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a preferred form of invention circuit;

FIG. 2 illustrates in fragment a modification of the FIG. I circuit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The specific SCR thyristor control for load input may be described as follows: A resistive voltage divider and power source comprises R1 in series with diode D1 and capacitor Cl.

The latter being in parallel with zener diode D2, both having common legs to ground. Through this configuration a reference supply voltage of approximately 10 volts DC is established below rectifier DI at the common junction of resistor R2, electrolytic capacitor CI and zener diode D2.

Connected below resistive voltage divider RI but above the anode of rectifying diode D1 is capacitor C2 whose outer side is connected directly to the gate control electrode of the thyristor SCR and in common also with the collector of transistor 01. Thus C2 charges upon AC input excursion at the same time turning on" the thyristor through its gate electrode. By virtue of C2 series connectioi'l with the AC input via resistive voltage divider RI, C2 maintains its charge and keeps the thyristor on until transistor 01 is biased so as to amplify its signal, but above all provide a low-resistive path R5 (approximately 40 ohms) to ground; thereby shunting current and voltage away from its collector and the thyristor gate electrode. The transistor itself and R5 therefor perform as a shunt when the transistor is so biased as to trigger.

For normal operating temperatures, (6090 F. in the electric blanket field, biasing numbers for R2, T1 and R3, direct voltage attenuation means to the base of OI, and the remainder should be approximately as follows:

D2=I0 volt, 1 watt R3=50K l80 Swing) C2=0.047 mfd.

These attenuations and variable resistances will permit transistor 01 with a high base to ground/emitter resistor R4 of approximately 12K and small emitter resistance of 40 ohms for R5 to develop through 01 and RS a feasible and easy shunt path for thedischarge of capacitor C2, once 01 has triggered. Naturally, depending on the strengthening or weakening of the resistive values of the directly coupled series base hookup, 01 will turn on or off, depending on the preselection position of R3 and the thermistor variables or their pluralities thereof. The cycle will thus be completed by and determined by the triggering on or off of 01 with its opposite effect on the gate of the thyristor. This is in marked contrast to normal amplified transistorized or other gate trigger means" which are normally used to turn on thyristor-switching means not turn them off.

The effect of the present application is to cut down the heating lead times and lag times of thermal control from the sleeping area or receptacle control areas, depending upon the specific optional disposition of thermistor or thermistors T and variable resistance R3.

As indicated, attenuation of the voltage is accomplished substantially via the resistances R2, R3 and the thermistor T to the base of the transistor Q1.

It will be apparent to those skilled in the art of manufacture that ultra miniaturization of the present control circuit by modifying to integrated or equivalent circuit means can be undertaken without departing from the spirit and structure of invention as set forth in the appended claims.

1. Electronic control for flexible heating element having AC current voltage supply which includes heating element and switching control means therefor, comprising in operative connection to the gate of said control:

A. a control power source including resistive voltage-divider means;.

B. the series connection therewith of atemperature sensor,

fixed and variable resistance to the base of a transistor;

C. transistor means, the collector of which has common connection to the gate of the switch means and a capacitance, the emitter of which has connection to ground, through leakage resistance whereby upon an increase in temperature above a preset maximum of the variable resistance, current is discharged through the capacitance via the collector and emitter of the transistor through the leakage resistance to ground, turning the switch "off".

2. The electronic control of claim 1 further comprising high resistance means connected to the base of the transistor to produce pronouncedly high amplification of temperature sensor signal thereto.

3. Electronic control of claim 1, including temperature override sensor means between the collector of the transistor and the gate of the switch.

4. The electronic control means of claim 2, including temperature override sensor means between the collector of the transistor and the gate of the switch.

5. Electronic control for flexible heating element having AC current voltage supply which includes heating element and switching control therefor, comprising in operative connection to the gate of said control:

A. power source, including resistive voltage divider means,

said voltage divider means including the series connection of a first resistance, first rectifier and a first capacitance to ground;

B. a second rectifier voltage stabilizer having parallel connection to the first capacitance and ground, said power source and components thereof having common series connection through a resistor to the input of a temperature sensor, the temperature sensor also being connected in series to the base of a transistor with selective temperature control means interposed therebetween;

C. a second capacitance connected between the voltage divider means and the collector of said transistor, the

emitter of the transistor being connected to ground, via

low resistive means, said collector having gate connection to the switching control, whereby upon response of said temperature sensor to an excess in heat, the transistor is triggered in such a manner as to discharge capacitor C2 and shunt current away from the gate-switching control to ground via a low resistive path.

6. The heater controls system of claim 5 is which high resistance means is connected to the base of the transistor to produce pronouncedly high amplification of temperature sensor signal.

7. The heater controls system of claim 6 including temperature override sensor means interposed between the collector of the transistor and the gage of the switching control.

8. Electronic on-off safety control circuit for flexible electric heating element having SCR switch therefor comprising in combination:

A. AC power source, the heater and switch being in series connection with said power source;

B. voltage-divider power supply for control circuit to provide current via a capacitor to the heater switch though its gate electrode;

C. the parallel connection of temperature sensor and capacitance interposed between the power supply and switch,

D. a transistor in the control circuit having base connection to the sensor and collector connection to the switch and capacitance, the emitter of said transistor being connected to ground;

E. means interposed between said sensor and the base of said transistor to selectively attenuate the signal of said sensor, whereby upon increase in temperature above the preselected temperature, current is shunted away from .the switch via the transistor to ground to shut off the source of heat to said heating element.

9. Electronic on-off safety control circuit according to claim 8 including temperature override sensor means interposed between transistor collector connection to SCR switch.

Claims

1. Electronic control for flexible heating element having AC current voltage supply which includes heating element and switching control means therefor, comprising in operative connection to the gate of said control: A. a control power source including resistive voltage-divider means; B. the series connection therewith of a temperature sensor, fixed and variable resistance to the base of a transistor; C. transistor means, the collector of which has common connection to the gate of the switch means and a capacitance, the emitter of which has connection to ground, through leakage resistance whereby upon an increase in temperature above a preset maximum of the variable resistance, current is discharged through the capacitance via the collector and emitter of the transistor through the leakage resistance to ground, turning the switch ''''off''''.

5. Electronic control for flexible heating element having AC current voltage supply which includes heating element and switching control therefor, comprising in operative connection to the gate of said control: A. power source, including resistive voltage divider means, said voltage divider means including the series connection of a first resistance, first rectifier and a first capacitance to ground; B. a second rectifier voltage stabilizer having parallel connection to the first capacitance and ground, said power source and components thereof having common series connection through a resistor to the input of a temperature sensor, the temperature sensor also being connected in series to the base of a transistor with selective temperature control means interposed therebetween; C. a second capacitance connected between the voltage divider means and the collector of said transistor, the emitter of the transistor being connected to ground, via low resistive means, said collector having gate connection to the switching control, whereby upon response of said temperature sensor to an excess in heat, the transistor is triggered in such a manner as to discharge capacitor C2 and shunt current away from the gate-switching control to ground via a low resistive path.

8. Electronic on-off safety control circuit for flexible electric heating element having SCR switch therefor comprising in combination: A. AC power source, the heater and switch being in series connection with said power source; B. voltage-divider power supply for control circuit to provide current via a capacitor to the heater switch though its gate electrode; C. the parallel connection of temperature Sensor and capacitance interposed between the power supply and switch, D. a transistor in the control circuit having base connection to the sensor and collector connection to the switch and capacitance, the emitter of said transistor being connected to ground; E. means interposed between said sensor and the base of said transistor to selectively attenuate the signal of said sensor, whereby upon increase in temperature above the preselected temperature, current is shunted away from the switch via the transistor to ground to shut off the source of heat to said heating element.