Power switching circuit

• US 4,016,428 A
• Filed: 11/13/1975
• Issued: 04/05/1977
• Est. Priority Date: 11/13/1975
• Status: Expired due to Term

• Current Assignee: Allan S. Beck
• Original Assignee: Allan S. Beck
• Inventors: Gutterman, Eric D.
• Primary Examiner(s): Hohauser, Herman J.
• Application Number:
  US05/631,438
• Time in Patent Office: 509 Days
• Field of Search: 307/116, 307/117, 307/118, 307/308, 307/248, 307/253, 317/DIG. 2, 340/258 R, 340/258 A, 340/258 B, 340/258 C, 340/279, 328/5
• US Class Current: 307/116
• CPC Class Codes: B41J 29/387 Automatic cut-off devices
• CPC Class Codes: H03K 17/962 Capacitive touch switches

Abstract

An automatic power switching circuit for controlling the application of electrical power to an electric typewriter or like apparatus. Radiated electrical energy emanating from alternating current machinery is transmitted to an input antenna by the touch of the operator. The input alternating current signal is shaped to produce electrical signal indicia responsive to the operator'"'"'s contact with the apparatus. The input signal is transmitted to a timing circuit to initiate the time-out of predetermined delay following which an output signal will be generated and the apparatus will be disconnected from the power source in the absence of human contact during the delay interval.

Claims

1. A power switching circuit for use with electrical appliances driveable by a power source comprising:

a. input signal means for receiving signal indicia representative of appliance operation;

b. timing means for initiating the time out of a predetermined interval, said time out commencing upon each signal indicia received by said input signal means, said timing means being coupled to said input signal means, said timing means outputting a signal responsive to said interval, said output signal being in a first state during said interval and changing to a second state following the termination of said interval;

c. a power switch connected to the electrical appliance, said power switch including control means for connecting and disconnecting the electrical appliance from the power source; and

d. isolation means for coupling the output signal of said timing means and the control means of said power switch whereby said control means disconnects the electrical appliance from the power source when the output signal of said timing means is in the second state thereof.

2. A power switching circuit as defined in claim 1 wherein said isolation means comprises a light dependent resistance and lamp assembly including a light emitting member and a light dependent resistive member, said light emitting member being connected to the output of said timing means, said light dependent resistive member being connected to the control means of said power switch.

3. A power switching circuit as defined in claim 1 wherein said input signal means includes an antenna comprising an electrically conductive member.

4. A power switching circuit as defined in claim 3 further including a power source, a first electrical translating element having at least three active regions, the first active region of said first electrical translating element being connected to said antenna, the second active region of said first electrical translating element being connected to a first pole of said power source, and the third active region of said first electrical translating element being coupled to the second pole of said power source and to the input of said timing means whereby signal indicia received by said antenna are transmitted to said timing means.

5. A power switching circuit as defined in claim 4 wherein said timing means includes threshold means for detecting a threshold signal, and further including a second electrical translating element having at least three active regions, the first active region of said second electrical translating element being connected to the second active region of said first electrical translating element, the second active region of said second electrical translating element being connected to the third active region of said first electrical translating element, and the third active region of said second electrical translating element being coupled to the threshold means of said timing means, a resistive member connected intermediate the third active region of said second electrical translating element and the first pole of said power source, and a capacitive member being connected intermediate the third active region of said second electrical translating element and the second pole of said power source whereby said resistive and capacitive members determine the threshold signal.

6. A power switching circuit as defined in claim 5 wherein said resistive member is a variable resistor.

7. A power switching circuit for use with electrical appliances driveable by a power source comprising:

a. an input antenna;

b. a first electrical translating member having base, collector and emitter regions, the base region of said first electrical translating member coupled to said input antenna;

c. a second electrical translating member having base, collector and emitter regions, the base and collector of said second electrical transmitting member being connected to the collector and emitter respectively of said first electrical translating member;

d. timing means for initiating the time-out of a predetermined interval, said time-out commencing upon the receipt of signal indicia by said input antenna, said timing means including threshold and discharge means for generating and detecting a threshold signal, said timing means producing an output signal responsive to the detection of said threshold signal, said timing means being coupled to the collector of said first electrical translating member, said threshold and discharge means being coupled to the emitter of said second electrical translating member;

e. charging means for controlling the rate of charging of said threshold signal, said charging means being connected to said threshold;

f. a power switch connected to the electrical appliance, said power switch including control means for connecting and disconnecting the electrical appliance from the power source; and

g. isolation means for coupling the output signal of said timing means and the control means of said power switch whereby said control means disconnects the electrical appliance from the power source when the output signal of said timing means is responsive to the discharge of said threshold signal.

8. A power switching circuit as defined in claim 7 wherein said isolation means comprises a light dependent resistive and lamp assembly including a light emitting member and a light dependent resistive member, said light emitting member being connected to the output of said timing means, said light dependent resistive member being connected to the control means of said power source.

9. A power switching circuit as defined in claim 7 wherein said charging means comprises a direct current power source having first and second poles of opposite polarity, a capacitive member connected intermediate the emitter of said second electrical translating member and the first pole of said power source, and a resistive member being connected intermediate the emitter of said second translating member and the second pole of said power source.

10. A power switching circuit as defined in claim 9 wherein said resistive member is a variable resistor.