CONTROLLER CIRCUIT
First Claim
1. A controller comprising a source of electrical power, thermocouple means, operational amplifier means connected to said source and to said thermocouple means and responsive to said thermocouple means for manifesting a first output signal when the temperature of said thermocouple means is below a predetermined limit, and a second output signal when the temperature of said thermocouple means is above said predetermined limit, sensing means connected to said source of power for sensing a restoration of power after an interruption thereof, and means for connecting said sensing means with said operational amplifier for forcing said amplifier to manifest said first output signal for a predetermined interval following said restoration.
0 Assignments
0 Petitions
Accused Products
Abstract
Temperature controllers including a sensing device, such as a thermocouple which is temperature compensated by means of a negative temperature coefficient resistance, and which generates a signal in response to the temperature of the thermocouple junction; an output circuit for manifesting a first output when a temperature limit is not exceeded and a second output when the limit is exceeded; a circuit which senses power interruption and forces the output circuit to manifest the first output for a limited time after the power is restored; and an alternative output circuit which provides a proportional controlling signal in response to the sensed temperature.
31 Citations
11 Claims
-
1. A controller comprising a source of electrical power, thermocouple means, operational amplifier means connected to said source and to said thermocouple means and responsive to said thermocouple means for manifesting a first output signal when the temperature of said thermocouple means is below a predetermined limit, and a second output signal when the temperature of said thermocouple means is above said predetermined limit, sensing means connected to said source of power for sensing a restoration of power after an interruption thereof, and means for connecting said sensing means with said operational amplifier for forcing said amplifier to manifest said first output signal for a predetermined interval following said restoration.
-
2. A controller according to claim 1 wherein said sensing means comprises delay means having a time constant corresponding to said predetermined interval, and selectively conductive means connected to said delay means and responsive thereto to assume its conductive state during said predetermined interval.
-
3. A controller according to claim 1 wherein said sensing means comprises a first transistor connected to said power source, connecting means for connecting said first transistor to said operational amplifier to force said amplifier to assume its first condition when said first transistor is conductive, a first timing circuit connected with said power supply and with a control element of said first transistor, a second transistor connected with said power supply and with said first timing circuit for selectively disabling said first timing circuit when said second transistor becomes conductive, and a second timing circuit interconnected with said power supply and a control element of said second transistor to cause said second transistor to become nonconductive at a predetermined time following said restoration, said first timing circuit being responsive to the operation of said second transistor to cause said first transistor to become nonconductive at a predetermined time following the time when said second transistor becomes nonconductive.
-
4. A controller according to claim 3 wherein said second timing circuit comprises a resistor connected with said power supply, and a capacitor connected to said resistor and adapted to be charged by said power supply through said resistor, and means for connecting said capacitor and said resistor to the gate of said second transistor for disabling said second transistor at said predetermined time.
-
5. A controller comprising sensing means for producing an electrical signal in response to the value of a physical parameter, an output terminal, and means connected to said sensing means and responsive to said electrical signal for producing a proportional signal at said output terminal, said proportional signal having a duty cycle related to the deviation of the sensed level of said parameter from a preselected level over a given range of said parameter, said last named means comprising an operational amplifier, a first voltage divider connected to the output of said operational amplifier, means for connecting said first voltage divider to the inverting input of said amplifier for supplying negative feedback to said amplifier, a second voltage divider connected with the output of said amplifier, means for connecting said second voltage divider to the noninverting input of said amplifier for supplying positive feedback to said amplifier, and capacitor means connected between said inverting input and a source of reference potential.
-
6. A controller according to claim 5 wherein said negative feedback means comprises a first resistor connected in series with a first diode between said first voltage divider and said inverting input, and a second resistor connected in series with a second diode between said first voLtage divider and said inverting input, said first and second diodes being connected in oppositely poled relationship.
-
7. A controller according to claim 5 including a source of a.c. power, a silicon controlled rectifier having its anode and cathode connected in series with said source, and means for connecting said output terminal to the gate terminal of said silicon controlled rectifier whereby a.c. current through said silicon controlled rectifier is controlled in response to said proportional signal.
-
8. A controller according to claim 5 wherein said sensing means includes thermocouple means for producing an electrical signal in response to the temperature of the junction of said thermocouple means, and generating means connected to said thermocouple means and responsive to said electrical signal for producing an output signal, said generating means including a source of regulated voltage, a first adjustable voltage divider connected between said regulated voltage and a source of reference potential, connecting means for connecting said first adjustable voltage divider to a first input of a differential amplifier, a second adjustable voltage divider connected between said source of regulated voltage and said reference potential, one terminal of said thermocouple means being connected with said second adjustable voltage divider and the other terminal of said thermocouple means being connected to the other input of said differential amplifier, whereby the differential in the potential of the two inputs to said differential amplifier is proportional to the temperature of said junction.
-
9. A controller according to claim 8 including a negative temperature coefficient resistor element connected in series with said second adjustable voltage divider, said resistor element being positioned adjacent the connection of said thermocouple means with said second voltage divider and the connection of said thermocouple means with said differential amplifier.
-
10. A controller according to claim 8 including a rheostat, said rheostat being connected across a portion of said second adjustable voltage divider, said rheostat establishing a range of potentials which may be selected by adjustment of said second voltage divider.
-
11. A controller comprising a source of electrical power, parameter sensing means, operational amplifier means connected to said source and to said parameter sensing means and responsive to said parameter sensing means for manifesting a first output signal when the parameter sensed by said parameter sensing means is below a predetermined limit, and a second output signal when the parameter sensed by said parameter sensing means is above said predetermined limit, power sensing means connected to said power source of power for sensing a restoration of power after an interruption thereof, and means for connecting said power sensing means with said operational amplifier for forcing said amplifier to manifest said first output signal for a predetermined interval following said restoration.
Specification