Pulse-width modulated relay
AssigneeCredence Systems Corporation
InventorPaul Dana Wohlfarth
Life of this patent
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Abstract
A relay controller intermittently connects a power supply across a relay coil with a controlled duty cycle whenever the relay coil is to generate a magnetic field for opening or closing the relay's contacts. The duty cycle with which the controller connects the power supply across the coil controls limits a steady-state amplitude of current passing through the coil, thereby controlling the intensity of the magnetic field the coil generates.
Claims35
An apparatus for providing a signal path between circuit nodes in response to a first control signal, the apparatus comprising:
- contacts for closing to provide the signal path between the circuit nodes and for opening to break the signal path between the circuit nodes selectively in response to a magnetic field;
- a coil for supplying the magnetic field to the contacts with an intensity proportional to a amplitude of a current passing through the coil;
- and
- first means for applying a pulsed signal across the coil in response to the first control signal, wherein the pulsed signal intermittently applies a voltage across that coil producing a current in the coil of amplitude rising to a steady state range that is a function of a duty cycle of the pulsed signal.
An apparatus for selectively providing signal paths between circuit nodes, the apparatus comprising:
- a plurality of contacts, each for closing to make the signal path between the circuit nodes and for opening to break the signal path between the circuit nodes selectively in response to a separate magnetic field;
- a plurality of coils, each corresponding to a separate one of the contacts, each coil for providing a separate magnetic field to its corresponding contact, the magnetic field having an intensity proportional to a amplitude of a current passing through the coil;
- and
- first means for applying a pulsed signal across any selected subset of the coils, wherein the pulsed signal produces a current in each coil of amplitude rising to a steady state range that is a function of a duty cycle of the pulsed signal.
A method for controlling a relay having contacts and a coil for producing a magnetic field for operating the contacts, the method comprising the steps of:
- a. connecting a voltage source across the coil,
- b. concurrently disconnecting the voltage source from across the coil and shorting the coil, and
- c. repeating steps a and b to until a current developed in the coil rises to a steady state amplitude range that is a function of a duty cycle with which the voltage source is connected across the coil, wherein the coil produces said magnetic field of sufficient intensity to operate the contacts.
Dependencies are inferred from the claim text.