Capacitive sensing dryer control

Claim 2

In a fabric drying machine having an enclosure for receiving moist fabrics to be dried: a. capacitive sensing means comprising: i. insulating means having a first surface exposed to the interior of said enclosure for contacting said fabrics, and a second surface unexposed to the interior of said enclosure; ii. first conductor means disposed upon said second surface of said insulating means to provide a first cApacitor plate; iii. second conductor means for coupling said first conductor means to one side of a source of alternating potential; iv. third conductor means for coupling said enclosure to a second side of said source of alternating potential, said moist fabrics when tumbled within said enclosure providing an electrical path between said enclosure and said insulating means to form a second capacitor plate with the conductivity of said path reflecting the degree of moisture retained by said fabrics; and b. control means responsive to the level of current flow in said second conductor means for terminating the operation of said fabric drying machine.

Claim 3

In a fabric drying machine having an enclosure for receiving moist fabrics to be dried, said enclosure having an insulating material disposed on the inner surface thereof: a. capacitive sensing means comprising; i. a dielectric housing having an outer surface exposed to the interior of said enclosure for contacting said fabrics, ii. conductive material disposed over the inner surface thereof to provide a first capacitor plate, iii. means for resistively coupling said conductive material to a source of alternating potential, iv. means for coupling said enclosure to a point of ground potential, said fabrics when tumbled within said enclosure providing an electrically-conductive path between said enclosure and said dielectric housing to form a second capacitor plate with the conductivity of said path reflecting the degree of moisture retained by said fabrics, b. control means for sensing the voltage across said resistive coupling means and providing an output representative thereof; and c. timer means coupled to said control means for terminating the operation of said fabric drying machine upon receiving said output from said control means.

Claim 4

In a fabric drying machine having an enclosure for receiving moist fabrics to be dried, said enclosure having an insulating material disposed on the inner surface thereof: a. capacitive sensing means comprising; i. a dielectric housing having an outer surface exposed to the interior of said enclosure for contacting said fabrics, ii. conductive material disposed over the inner surface thereof to provide a first capacitor plate, iii. means for resistively coupling said conductive material to a source of alternating potential, iv. means for coupling said enclosure to a point of ground potential, said fabrics when tumbled within said enclosure providing an electrically-conductive path between said enclosure and said dielectric housing to form a second capacitor plate with the conductivity of said path reflecting the degree of moisture retained by said fabrics, b. control means for sensing the voltage across said resistive coupling means and providing an output representative thereof; and c. timer means coupled to said control means for terminating the operation of said fabric drying machine upon receiving said output from said control means.

Claim 5

The invention as recited by claim 2, wherein said control means includes an amplifier means having a high input impedance and a high gain, said resistive coupling means being coupled to the input of said amplifier, and said control means further including gated switching means, said switching means being adapted to be operated in response to an output signal derived from said amplifier means.

Claim 6

The invention as recited in claim 2, wherein said control means comprises amplifier means having a high input impedance and including at least one transistor, said resistive coupling means being connected to the input terminal of said amplifier, said transistor being operatively coupled to an output terminal of said amplifier means for disabling said switching means in response to a signal outputted by said amplifier means.

Claim 7

In a fabric drying machine, a capacitive sensor, comprising: a. a rotatable enclosure for tumbling moist fabrics confined therein, said enclosure being adapted to be coupled to a first side of a source of alternating potential; b. insulator means having a first and a second side, said first side of said insulator means communicating with the interior of said enclosure for contacting said fabrics, said fabrics providing an electrically conductive path between said enclosure and said first side of said insulator means to form a capacitor plate; and c. conductor means disposed upon said second side of said insulator means to provide a capacitor plate and coupled to a second means connecting said capacitive sensor in a control circuit for controlling the operation of the drying machine in response the moisture content of the fabric.

Claim 8

In a fabric drying machine, a capacitive sensor, comprising: a. a rotatable enclosure for tumbling moist fabrics confined therein, said enclosure being adapted to be coupled to a first side of a source of alternating potential; b. insulator means having a first and a second side, said first side of said insulator means communicating with the interior of said enclosure for contacting said fabrics, said fabrics providing an electrically conductive path between said enclosure and said first side of said insulator means to form a capacitor plate; and c. conductor means disposed upon said second side of said insulator means to provide a capacitor plate and coupled to a second means connecting said capacitive sensor in a control circuit for controlling the operation of the drying machine in response the moisture content of the fabric.

Claim 9

In a fabric drying machine having an enclosure for receiving moist fabrics to be dried: a. capacitive sensing means comprising: i. first conductive means being adapted to be connected to a first side of a source of alternating potential and providing a first capacitor plate, ii. insulator means having a first and second side, said second side of said insulator means communicating with the interior of said enclosure and said first side disposed adjaCent said first conductive means, iii. second conductive means adapted to be connected to a second side of said source of alternating potential and communicating with said enclosure, said moist fabrics when tumbled within said enclosure providing an electrical path between said second conductive means and said insulator means to form a second capacitor plate with the conductivity of said path reflecting the degree of moisture retained by said fabrics; and b. control means coupled to said capacitive sensing means for terminating the operation of said fabric drying machine in response to a predetermined change in the amount of current flowing through said capacitive sensing means.

Claim 10

In a fabric drying machine having an enclosure for receiving moist fabrics to be dried: a. capacitive sensing means comprising: i. first conductive means being adapted to be connected to a first side of a source of alternating potential and providing a first capacitor plate, ii. insulator means having a first and second side, said second side of said insulator means communicating with the interior of said enclosure and said first side disposed adjaCent said first conductive means, iii. second conductive means adapted to be connected to a second side of said source of alternating potential and communicating with said enclosure, said moist fabrics when tumbled within said enclosure providing an electrical path between said second conductive means and said insulator means to form a second capacitor plate with the conductivity of said path reflecting the degree of moisture retained by said fabrics; and b. control means coupled to said capacitive sensing means for terminating the operation of said fabric drying machine in response to a predetermined change in the amount of current flowing through said capacitive sensing means.