Dryer control system using moisture sensor and semiconductors to control cycle

Claim 2

In a dryer control which is responsive to desired moisture content level in articles of fabric to end the drying period, and a dryness sensor circuit having a dryness sensor comprising a pair of spaced electrodes which may be bridged by an article of fabric undergoing drying, means for rejecting false signals caused by static electricity generated by the drying articles comprising means associated with said sensor for grounding one polarity of static signals and means associated with said sensor for blocking the other polarity of static signals, said means for blocking static signals including a diode connected to one of said electrodes, and said means for grounding static signals including a capacitor connected between said diode and ground, the other electrode being connected to ground.

Claim 3

In a dryer control according to claim 1, wherein said sensor circuit comprises means for adjusting the desired moisture level and means for adjusting the control sensitivity.

Claim 4

In a dryer control according to claim 1, wherein said sensor circuit comprises first resistor means for establishing the desired moisture level and second resistor means for establishing the control sensitivity.

Claim 5

In a dryer control according to claim 1, wherein said sensor circuit comprises means for contemporaneously adjusting the desired moisture level and the control sensitivity.

Claim 6

In a dryer control according to claim 4, wherein said means for contemporaneously adjusting the desired moisture level and the control sensitivity comprises a pair of ganged variable resistors connected in a circuit of the dryer control and mechanically linked together so that adjustment of the desired moisture level also provides an adjustment of the control sensitivity of the circuit.

Claim 7

In a dryer control according to claim 5, wherein the variable resistors are linked so that proportional resistance portions Of each of the resistors are connected into the circuit as the resistors are varied.

Claim 8

In a dryer control according to claim 1, comprising means for selectively extending the drying period in time increments beyond the time required to reach the desired moisture content level.

Claim 9

In a dryer control according to claim 1, wherein the control includes means for limiting the voltage across the sensor to a DC voltage of relatively low magnitude so that the sensor can be connected into an integrated circuit.

Claim 10

Dryness sensing apparatus for controlling the operation of the drying means of a laundry appliance, comprising: a dryness sensor including a pair of spaced electrodes for contacting an article of fabric undergoing drying, said electrodes connected across an electrical supply, a diode connected to one of said electrodes and a capacitor connected between said diode and the other of said electrodes which is connected to a reference potential of the electrical supply, said diode effective to block static signals of one polarity and pass via said capacitor static signals of the opposite polarity to the supply reference, means for establishing a desired moisture content level, and means connected to the junction of said diode and said capacitor for providing a control signal in response to the detection of the desired moisture content level; and means connected to said dryness sensor and operable in response to said control signal to terminate operation of the drying means.

Claim 11

Dryness sensing apparatus for controlling the operation of the drying means of a laundry appliance, comprising: a dryness sensor including a pair of spaced electrodes for contacting an article of fabric undergoing drying, said electrodes connected across an electrical supply, a diode connected to one of said electrodes and a capacitor connected between said diode and the other of said electrodes which is connected to a reference potential of the electrical supply, said diode effective to block static signals of one polarity and pass via said capacitor static signals of the opposite polarity to the supply reference, means for establishing a desired moisture content level, and means connected to the junction of said diode and said capacitor for providing a control signal in response to the detection of the desired moisture content level; and means connected to said dryness sensor and operable in response to said control signal to terminate operation of the drying means.

Claim 12

A dryness sensing apparatus according to claim 9, wherein said means for establishing a desired moisture content level includes adjustable means for changing the desired moisture content level.

Claim 13

A dryness sensing apparatus according to claim 9, wherein said means for providing a control signal includes adjustable means for varying its sensitivity to the sensed moisture content level.

Claim 14

A dryness sensing apparatus according to claim 9, wherein there is a series of time delay circuits connected between said dryness sensor and said means for terminating operation of said drying means to extend the drying time by selected intervals, and wherein said means for providing a control signal includes means for applying periodic reference signals to said series of time delay circuits.

Claim 15

A dryness sensing apparatus according to claim 9, wherein said means for establishing a desired moisture content level comprises means for adjusting the duration of a time period wherein if no moisture signal is received by the dryness sensor from the fabric undergoing drying by the end of the time period, the drying cycle is terminated.

Claim 16

A dryness sensing apparatus according to claim 9, wherein said means for terminating operation of the drying means comprises adjustable means for providing selected delay times for terminating drying beyond that drying time elapsed upon sensing of the desired moisture content level.

Claim 17

A dryness sensing apparatus according to claim 14, wherein said adjustable means includes means for generating delayed control signals, means for selecting the delay time of said control signals, and means for interposing said adjustable means between said means for providing a control signal and the drying means.