Emhart Industries, Inc.

Robert G Bristol

Charles E Scott

Louis M Sandler

Robert L Smith

The present invention utilizes the fact that the rate of change of the amplitude of a sinusoidal waveform is substantially constant within an interval of such waveform near its zero crossing. A circuit for measuring peak amplitudes of sinusoidal waveforms includes a voltage differentiator for differentiating between a first and second reference selected within the interval of a sinusoidal waveform wherein the rate of change of the amplitude is substantially constant; a time interval calculator for measuring a time interval between the references; a frequency determinator for determining the frequency of oscillation of the waveform; and a processing unit responsive to the voltage differentiator, the time interval calculator, and the frequency determinator for determining a peak amplitude of the waveform. In accordance with the present invention, a method of controlling the operation of an induction motor of the type having a main winding and at least one start winding utilizes the circuit for measuring peak amplitudes of sinusoidal waveforms. The motor start control system includes a current sensing device for producing a waveform proportional to the main winding current of the motor and a control circuit responsive to the waveform for deenergizing the start winding of the motor when the amplitude of the waveform is less than a threshold level wherein the threshold level is variable in accordance with the start main winding current. By continuously determining peak amplitudes of the waveform which is proportional to main winding current of the motor and storing an initial peak amplitude of the waveform, the start winding is deenergized when a peak amplitude of the waveform becomes less than a defined percentage of the stored initial peak amplitude.

Control system and method for motor starting

A system for controlling the operation of an appliance of the type having a plurality of machine functions to be activated and deactivated in accordance with a control strategy includes a plurality of selectable cycles each made up of a series of events and an array of user actuatable membrane switching devices for selecting at least one cycle of operation for the appliance. The array of membrane switching devices also allow the user to program an optional event within the selected cycle and to select a time period for at least one of the events of the selected cycle. A control logic includes a resident program with a series of instructions for the operation of the applicance and a memory for storing data which is retrievable in response to actuation of the membrane switching devices so that the appliance operates in accordance with the resident program and the retrieved data. A display panel includes various individual displays for indicating the selected cycle, optional event, time period for the one event of the cycle, and the time remaining in the selected cycle. A method of controlling the operation of the appliance includes displaying a time period for and the time remaining in a selected cycle, continuously monitoring the membrane switching devices to detect user actuated changes in the operation of the appliance during the selected cycle, and disabling certain membrane switching devices during the selected cycle to thereafter eliminate the possibility of user actuated changes associated with such disabled switching devices.

Control system for appliances and the like

A plurality of conductive strips are situated on a receptacle for receiving a liquid which at least partially comprises dielectric material. A first electrode is commonly situated in spaced relation to each of the conductive strips and provides an electrical signal which is capacitively transmitted between the electrode and each of the conductive strips. A second electrode is commonly situated in spaced relation to each of the conductive strips and the electrical signal is capacitively transmitted between each conductive strip and the second electrode. The electrical signal being capacitively transmitted is modified as the liquid comes in proximity to each conductive strip whereby the level of the liquid is detected.

Capacitive scheme for measuring the level of a liquid

A detection circuit for detecting discrete states of multiple capacitive sensing devices in a continuum provides an output which is linearly variable with respect to changes in the states of the sensing devices. The circuit uses either a time interval measurement or voltage measurement which has a magnitude which linearly corresponds to changes in the states of the sensing devices. By continuously monitoring these outputs, a continuous indication of discrete changes in the states of the sensing devices is detectable. In accordance with the present invention, a single drive electrode and a single sense electrode in combination with a plurality of sensing devices capacitively transmit electrical pulses in accordance with the various states of the sensing devices whereby the detection circuit detects discrete changes in a state of the sensing devices in a continuum.

Growing community of inventors

Everett, MA, United States of America

Robert G Bristol