Electric blanket and control
DCFirst Claim
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1. An electric blanket, said blanket comprising:
- a heating element extending through said blanket so that, upon receiving electric current from a power source, said element heats said blanket;
a resistive element having a resistance (R1) and being disposed electrically in series between said power source and said heating element;
a full-wave rectifier disposed between said power source and said heating element so that said rectifier fully rectifies said current applied to said heating element; and
a regulator circuit connected to said heating element, said regulator circuit including a processor in communication with said power source and said resistive element and configured to measure a voltage drop (V1) across said power source and a voltage drop (V2) across said resistive element, wherein said processor is configured to divide V2 by R1, thereby determining a current (I)through said heating element, divide V1 by I, thereby determining a resistance (R2) having a known relationship to the resistance of said heating element, control delivery of said electric current from said power source to said heating element responsively to R2 so that said heating element heats to a desired temperature, and discontinue delivery of said electric current from said power source to said heating element when I exceeds a predetermined threshold.
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Abstract
An electric blanket includes a heating element extending through the blanket so that, upon receiving electric current from a power source, the element heats the blanket. A regulator circuit is connected to the element. It is configured to measure the resistance of the element and to control delivery of the electric current from the power source to the element responsively to the resistance so that the element heats to a desired temperature.
75 Citations
38 Claims
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1. An electric blanket, said blanket comprising:
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a heating element extending through said blanket so that, upon receiving electric current from a power source, said element heats said blanket;
a resistive element having a resistance (R1) and being disposed electrically in series between said power source and said heating element;
a full-wave rectifier disposed between said power source and said heating element so that said rectifier fully rectifies said current applied to said heating element; and
a regulator circuit connected to said heating element, said regulator circuit including a processor in communication with said power source and said resistive element and configured to measure a voltage drop (V1) across said power source and a voltage drop (V2) across said resistive element, wherein said processor is configured to divide V2 by R1, thereby determining a current (I)through said heating element, divide V1 by I, thereby determining a resistance (R2) having a known relationship to the resistance of said heating element, control delivery of said electric current from said power source to said heating element responsively to R2 so that said heating element heats to a desired temperature, and discontinue delivery of said electric current from said power source to said heating element when I exceeds a predetermined threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
a connection circuit configured to connect said heating element to a power source, and a control circuit in operative communication with said connection circuit and said heating element, said control circuit configured to selectively connect said heating element to said power source through said connection circuit responsively to R2. -
9. The blanket as in claim 8, wherein said connection circuit includes a first triac operatively in line between said heating element and a connection to said power source and wherein said control circuit drives a control input to said first triac.
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10. The blanket as in claim 9, wherein said regulator circuit includes an optically isolated triac operatively between said control input to said first triac and a signal line in said connection circuit between said power source connection and said heating element and wherein said control circuit drives a control input to said optically isolated triac, thereby driving said control input to said first triac.
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11. The blanket as in claim 8, wherein said control circuit is configured to alternatingly connect and disconnect said heating element from said power source to maintain said desired temperature.
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12. The blanket as in claim 11, wherein said control circuit is configured to connect said heating element from said power source during a predetermined phase of an alternating current signal on said connection circuit.
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13. The blanket as in claim 8, wherein said regulator circuit is configured to electrically disconnect said heating element from said power source upon detection of said resistance above a predetermined level.
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14. The blanket as in claim 8, wherein said regulator circuit is configured to electrically disconnect said element from said power source upon detection of said resistance below a predetermined level.
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15. The blanket as in claim 13, wherein said regulator circuit is configured to electrically connect said heating element to said power source after a predetermined period following said detection.
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16. The blanket as in claim 12, wherein said regulator circuit is configured to electrically disconnect said heating element from said power source upon detection of said resistance above a predetermined level.
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17. An electric blanket, said blanket comprising:
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a heating element wire wound about a core and extending through said blanket so that, upon receiving electric current from a power source, said heating element heats said blanket;
a first triac operatively in line between said heating element and a connection to a power source;
an optically isolated triac operatively between a control input to said first triac and a signal line between said power source connection and said heating element so that activation of said optically isolated triac activates said first triac to deliver electric current from said power source connection to said heating element;
a resistive element having a resistance (R1) and being disposed electrically in series between said power source and said heating element;
a full-wave rectifier disposed between said power source and said heating element so that said rectifier fully rectifies said current applied to said heating element; and
a processor in communication with said power source and said resistive element and configured to measure a voltage drop (V1) across said power source and a voltage drop (V2) across said resistive element, wherein said processor is configured to divide V2 by R1, thereby determining a current (I) through said heating element, divide V1 by I, thereby determining a resistance (R2) having a known relationship to the resistance of said element, and activate said optically isolated triac responsively to R2 so that said element heats to a desired temperature, and discontinue delivery of said electric current from said power source to said element when I exceeds a predetermined threshold. - View Dependent Claims (18, 19, 20, 21, 22, 23)
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24. A method for heating an electric blanket, said method comprising the steps of:
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providing a heating element extending through said blanket so that, upon receiving electric current from a power source, said heating element heats said blanket;
fully rectifying said current applied to said heating element;
measuring a voltage drop (V1) across said power source and a voltage drop (V2) across a resistive element in series between said power source and said heating element, wherein said resistive element has a known resistance (R1);
dividing V2 by R1, thereby determining a current (I) through said heating element;
dividing V1 by I, thereby determining a resistance (R2) having a known relationship to the resistance of said heating element;
controlling delivery of said electric current from said power source to said heating element responsively to R2 so that said heating element heats to a desired temperature; and
discontinuing delivery of said electric current from said power source to said heating element when I exceeds a predetermined threshold. - View Dependent Claims (25, 26, 27, 28, 29, 30)
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31. An electric blanket, said blanket comprising:
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a heating element extending through said blanket so that, upon receiving an alternating electric current from a power source, said element heats said blanket; and
a regulator circuit connected to said heating element, said regulator circuit configured to measure the resistance of said heating element and to control delivery of said electric current from said power source to said heating element responsively to said resistance so that said heating element heats to a desired temperature, wherein said regulator circuit is configured to deliver said electric current to said heating element in at least one predetermined ratio of cycle on-time to cycle off-time, based on a predetermined scale, and wherein said predetermined ratio is associated with said desired temperature and is less than one. - View Dependent Claims (32, 33, 34)
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36. An electric blanket, said blanket comprising:
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a heating element extending through said blanket so that, upon receiving an alternating electric current from a power source, said element heats said blanket; and
a regulator circuit connected to said heating element, said regulator circuit including memory and being configured to measure the resistance of said heating element, determine a first temperature of said heating element corresponding to said resistance, and control delivery of said electric current from said power source to said heating element responsively to said temperature so that said first temperature changes toward a desired temperature, wherein said regulator circuit includes memory in which is stored a value corresponding to the length of said heating element, a value corresponding to a temperature coefficient of said heating element and a value corresponding to a rated resistance of said heating element, and wherein said regulator circuit is configured to calculate said first temperature based on said length, said temperature coefficient and said rated resistance. - View Dependent Claims (35)
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37. An electric blanket, said blanket comprising:
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a heating element extending through said blanket so that, upon receiving an alternating electric current from a power source, said element heats said blanket; and
a regulator circuit connected to said heating element, said regulator circuit including memory and being configured to measure the resistance of said heating element, determine a first temperature of said heating element corresponding to said resistance; and
control delivery of said electric current from said power source to said heating element responsively to said temperature so that said first temperature changes toward a desired temperature, wherein said regulator circuit includes memory in which is stored a plurality of tables, each table including a plurality of said first temperatures and a range of resistances respectively corresponding to said first temperatures, wherein said ranges are non-overlapping and respectfully correspond to a plurality of different said heating elements, and wherein said regulator circuit is configured to select said range within which said heating element resistance falls and to select one of said first temperatures corresponding to said selected range based on a comparison of said heating element resistance to said resistances within said selected range. - View Dependent Claims (38)
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Specification