Method for (prepolarizing and centering) operating a piezoceramic power switching device

Abstract

This application describes a number of novel advanced piezoelectric ceramic power switching devices which are mounted within protective gastight enclosures that are either evacuated to a high degree of vacuum or filled with an inert gas protective atmosphere. The devices thus constructed are capable of operating over a range of load voltages extending from about 100 volts to 5000 volts or more with corresponding currents of from a few amperes to hundreds of amperes and wherein it is possible to provide a number of such structures in a single common protective gastight enclosure. For certain circuit applications the devices thus constructed have unpoled portions on which are mounted either passive circuit components such as resistors, capacitors and the like or active semiconductor devices all interconnected in circuit relationship with each other and the switching devices by using printed circuit or integrated circuit fabrication techniques. In these devices, stray circuit impedances whether capacitive, inductive or resistive in nature can be reduced to an absolute minimum by appropriate designs. Such complementary circuit components and active semiconductor devices can be, if desired, mounted within the common protective enclosures in close proximity to the piezoceramic switching devices to which they are connected, or alternatively may be mounted exteriorly of the protective enclosures.

Description

This application is a divisional application of copending parent application U.S. Ser. No. with,preceedingpreceedingresult15B18characteristics of a vacuum or protective gas atmosphere in which the devices are mounted. Because of these characteristics and the protective atmosphere provided by the gastight enclosure, plural switching devices can be mounted in a single common enclosure and the need for conformal protective coatings or enscapulation encapsulation of the prepolarized portion of the piezoceramic plate elements is obviated. Further, it is possible to employ contact materials such as copper-vanadium alloys having low melting points for establishment of stable arcs to reduce di/dt at current chop (current extinction) during switching and high voltage withstandability. This is made possible since the protective atmosphere in which the contacts are used provides higher voltage withstandability upon contact opening and at current extinction and maintain while maintaining the contacts in a non-oxidizing atmosphere such as a vacuum to protect the low melting point contacts and prevent changes in their contact resistance. Because of the higher dielectric strength and other characteristics noted above which are achieved while operating in a vacuum or protective gas atmosphere, voltage withstandability of at least 2000 volts per mil are is obtainable with such devices. Further, repeatability timing of bender charging, contact closing, bender discharging, contact opening and reverse bender assist, as needed, is optimized.

INDUSTRIAL APPLICABILITY

The invention makes available a family of novel advance advanced piezoelectric ceramic power switching devices which are mounted within protective gastight enclosures that can be either evacuated to a high degree of vacuum of the order of 10-10 to 10-6 Torrs Torr or filled with an inert protective gas atmosphere such as nitrogen, argon, SF6 or the like. The switching devices thus fabricated can be used over a wide power range for both industrial, commercial and residential applications.

Having described several embodiments of advanced piezoceramic power switching structures employing protective gastight enclosures and constructed in accordance with the invention, it is believed obvious that other modifications and variations of the invention will be suggested to those skilled in the art in the light of the above teachings. It is therefore to be understood that changes may be made in the particular embodiments of the invention described which are within the full intended scope of the invention as defined by the appended claims.

Claims

1. The method of prepolarizing and centering the movable piezoceramic bender member of a piezoceramic bender-type switching device contained within a protective gastight enclosure which comprises substantially completing the fabrication assembly of all of the major components of the piezoceramic switching device into a unitary structure mounted within the protective gastight enclosure and sealed closed, applying a relativey relatively high value prepolarization potential to the respective piezoceramic plate elements of the bender member while maintaining the plate elements near their Curie temperature to achieve dipole alignment of the dipoles of the piezoceramic material and simultaneously adjusting the relative magnitudes of the prepolarizing potential applied to the respective piezoceramic plate elements of the bender member to cause it to precisely position the movable switch contacts mounted thereon relative to fixed load current switch contacts of the switching device.

2. A method of centering the movable piezoceramic bender member of a piezoelectric bender-type switching device contained within a protective gastight enclosure, the bender member having a pair of plate elements each having a planar outside surface, conductive surfaces on the planar surfaces, and a switch contact on the outside planar surface of each plate element adjacent a movable end of the bender member, the switching device having a fixed contact adjacent each of the movable contacts, comprising the steps of

substantially completing the fabrication assembly of the major components of the switching device into a unitary structure mounted within the protective gastight enclosure, and

applying an initial potential to the conductive surfaces of the plate elements of the bender member and adjusting the relative magnitudes of the initial potential applied to the respective plate elements of the bender member to precisely position the bender member switch contacts between the fixed switch contacts.

3. The method of initially polarizing and centering the movable piezoceramic bender member of a piezoceramic bender-type switching device contained within a protective gastight enclosure which comprises substantially completing the fabrication assembly of the major components of the switching device into a unitary structure mounted within the protective gastight enclosure, applying a relatively high value initial polarizing potential to the respective piezoceramic plate elements of the bender member, and simultaneously adjusting the relative magnitudes of the initial polarization potential applied to the respective piezoceramic plate elements of the bender member to cause it to precisely position movable switch contacts mounted thereon relative to fixed load current switch contacts of the switching device.

4. The method of claim 2 wherein the fixed contacts and movable contacts enable make or break connection to at least two separate electrically conductive paths extending through the contacts. 5. The method of claim 2 wherein the plate elements include a poled and unpoled portion with the initial polarizing potential being selectively applied to the poled portion. 6. The method of claim 5 wherein the unpoled portion of the selected plate element remains electrically neutral and physically unstrained during switching device operation.

7. The method of claim 5 wherein electric circuit components in the form of passive circuit elements and/or active semiconductor devices are physically supported by the unpoled portion of the selected plate element and are electrically connected in circuit relationship with the switching device. 8. The method of claim 2 wherein there are a plurality of bender-type piezoelectric ceramic switching devices physically mounted within a single common gastight protective enclosure with each such device being operated for controlling the electric load current therethrough. 9. The method of claim 8 wherein each bender-type piezoelectric ceramic switching device within the common protective enclosure includes its own coacting first and second electric switch contact means and operates independently of the other switching devices mounted within the common protective enclosure. 10. The method of claim 8 wherein the bender-type piezoelectric ceramic switching devices mounted within the common protective enclosure are made to operate interdependently of the other switching devices mounted within the same common protective enclosure. 11. The method of claim 3 wherein the fixed contacts and movable contacts enable make or break connection to at least two separate electrically conductive paths extending through the contacts. 12. The method of claim 3 wherein the plate elements include a poled and unpoled portion with the initial polarizing potential being selectively applied to

the poled portion. 13. The method of claim 12 wherein the unpoled portion of the selected plate element remains electrically neutral and physically unstrained during switching device operation. 14. The method of claim 12 wherein electric circuit components in the form of passive circuit elements and/or active semiconductor devices are physically supported by the unpoled portion of the selected plate element and are electrically connected in circuit relationship with the switching device. 15. The method of claim 3 wherein there are a plurality of bender-type piezoelectric ceramic switching devices physically mounted within a single common gastight protective enclosure with each such device being operated for controlling the electric load current therethrough. 16. The method of claim 15 wherein each bender-type piezoelectric ceramic switching device within the common protective enclosure includes its own coacting first and second electric switch contact means and operates independently of the other switching devices mounted within the common protective enclosure. 17. The method of claim 15 wherein the bender-type piezoelectric ceramic switching devices mounted within the common protective enclosure are made to operate interdependently of the other switching devices mounted within the same common protective enclosure.