초록 ▼

Zero crossing synchronous AC switching circuits are provided which employ piezoelectric ceramic bender-type switching devices for use in supplying loads of a resistive, inductive or capacitive nature. The circuits include zero crossing sensing sub-circuits for sensing the passage through zero value

Zero crossing synchronous AC switching circuits are provided which employ piezoelectric ceramic bender-type switching devices for use in supplying loads of a resistive, inductive or capacitive nature. The circuits include zero crossing sensing sub-circuits for sensing the passage through zero value of a supply source of alternating current voltage and/or current and for deriving zero crossing timing signals representative of the occurrance of the zero crossings. The zero crossing timing signals are employed to control operation of a bender energizing potential control sub-circuit for selectively controlling application or removal of a bender energizing potential across the piezoelectric bender member of the bender-type switching devices. Phase shift networks are included in the circuit for shifting the phase or time of application of the selectively applied bender energization potential so as to cause it to close or open a set of load current carrying switch contacts substantially at or near the naturally occurring zero crossings of the applied alternating current supplying the load.

대표청구항 ▼

A zero crossing synchronous AC switching circuit for alternating current systems employing at least one piezoelectric ceramic bender-type switching device having load current carrying electric switch contacts and at least one prepolarized piezoelectric ceramic bender number for selectively closing o

A zero crossing synchronous AC switching circuit for alternating current systems employing at least one piezoelectric ceramic bender-type switching device having load current carrying electric switch contacts and at least one prepolarized piezoelectric ceramic bender number for selectively closing or opening the electric switch contacts to control load current flow therethrough, said prepolarized piezoelectric ceramic bender member comprising a pair of planar prepoled piezoelectric ceramic plate elements secured in opposed parallel relationship sandwich fashion on opposite sides of a central conductive surface and having respective outer conductive surfaces that are insulted from each other and the central conductive surface by the respective intervening piezoelectric ceramic plate element thickness, said piezoelectric ceramic bender member further carrying at least one movable contact which coacts with a fixed contact to open and close the electric switch contact means of said switching device, zero crossing sensing circuit means for sensing the passage through zero value of a supply source of alternating current applied across the circuit and for deriving a zero crossing timing signal representative of the occurrence of the zero crossings, bender energization potential control circuit means responsive to the zero crossing timing signals for selectively controlling application and removal of a bender energizing potential across a piezeoelectric ceramic bender member of the bender-type switching device to selectively apply said bender energization potential to each piezoelectric ceramic plate element and having the same polarity as the polarity of the prepole electric field previously permanently induced in said prepoled piezoelectric ceramic plate elements so that no depolarization of said piezeoelectric ceramic plate elements occurs during successive operations of the switching device, and phase shift circuit means effectively responsive to the applied alternating current for shifting the timing of the application and removal of the bender energizing potential to the piezeoelectric ceramic bender member by a preselected phase shift interval relative to the naturally occurring zero crossings of the applied alternating circuit.