Abstract:
A method and structure for an electrical switch. According to the structure of the present invention, a liquid-filled chamber is housed within a solid material. A plurality of switch contacts within the liquid-filled chamber are coupled to the solid material, while a plurality of piezoelectric elements are coupled to a plurality of membranes. The plurality of membranes are coupled to the liquid-filled chamber. The plurality of switch contacts are coupled to a plurality of liquid metal globules. According to the method, a piezoelectric element is actuated, causing a membrane element to be deflected. The deflection of the membrane element increases pressure of actuator liquid and the increase in pressure of the actuator liquid breaks a liquid metal connection between a first contact and a second contact of the electrical switch.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is related to the following co-pending U.S. patent applications, being identified by the below enumerated identifiers and arranged in alphanumerical order, which have the same ownership as the present application and to that extent are related to the present application and which are hereby incorporated by reference:
         Application 10010448-1, titled “Piezoelectrically Actuated Liquid Metal Switch”, filed May 2, 2002 and identified by Ser. No. 10/137,691;   Application 10010529-1, “Bending Mode Latching Relay”, and having the same filing date as the present application;   Application 10010531-1, “High Frequency Bending Mode Latching Relay”, and having the same filing date as the present application;   Application 10010570-1, titled “Piezoelectrically Actuated Liquid Metal Switch”, filed May 2, 2002 and identified by Ser. No. 10/142,076;   Application 10010571-1, “High-frequency, Liquid Metal, Latching Relay with Face Contact”, and having the same filing date as the present application;   Application 10010572-1, “Liquid Metal, Latching Relay with Face Contact”, and having the same filing date as the present application;   Application 10010573-1, “Insertion Type Liquid Metal Latching Relay”, and having the same filing date as the present application;   Application 10010617-1, “High-frequency, Liquid Metal, Latching Relay Array”, and having the same filing date as the present application;   Application 10010618-1, “Insertion Type Liquid Metal Latching Relay Array”, and having the same filing date as the present application;   Application 10010634-1, “Liquid Metal Optical Relay”, and having the same filing date as the present application;   Application 10010640-1, titled “A Longitudinal Piezoelectric Optical Latching Relay”, filed Oct. 31, 2001 and identified by Ser. No. 09/999,590;   Application 10010643-1, “Shear Mode Liquid Metal Switch”, and having the same filing date as the present application;   Application 10010644-1, “Bending Mode Liquid Metal Switch”, and having the same filing date as the present application;   Application 10010656-1, titled “A Longitudinal Mode Optical Latching Relay”, and having the same filing date as the present application;   Application 10010664-1, “Method and Structure for a Pusher-Mode Piezoelectrically Actuated Liquid Metal Optical Switch”, and having the same filing date as the present application;   Application 10010790-1, titled “Switch and Production Thereof”, filed Dec. 12, 2002 and identified by Ser. No. 10/317,597;   Application 10011055-1, “High Frequency- Latching Relay with Bending Switch Bar”, and having the same filing date as the present application;   Application 10011056-1, “Latching Relay with Switch Bar”, and having the same filing date as the present application;   Application 10011064-1, “High Frequency Push-mode Latching Relay”, and having the same filing date as the present application;   Application 10011065-1, “Push-mode Latching Relay”, and having the same filing date as the present application;   Application 10011121-1, “Closed Loop Piezoelectric Pump”, and having the same filing date as the present application;   Application 10011329-1, titled “Solid Slug Longitudinal Piezoelectric Latching Relay”, filed May 2, 2002 and identified by Ser. No. 10/137,692;   Application 10011344-1, “Method and Structure for a Slug Pusher-Mode Piezoelectrically Actuated Liquid Metal Switch”, and having the same filing date as the present application;   Application 10011345-1, “Method and Structure for a Slug Assisted Longitudinal Piezoelectrically Actuated Liquid Metal Optical Switch”, and having the same filing date as the present application;   Application 10011397-1, “Method and Structure for a Slug Assisted Pusher-Mode Piezoelectrically Actuated Liquid Metal Optical Switch”, and having the same filing date as the present application;   Application 10011398-1, “Polymeric Liquid Metal Switch”, and having the same filing date as the present application;   Application 10011410-1, “Polymeric Liquid Metal Optical Switch”, and having the same filing date as the present application;   Application 10011436-1, “Longitudinal Electromagnetic Latching Optical Relay”, and having the same filing date as the present application;   Application 10011437-1, “Longitudinal Electromagnetic Latching Relay”, and having the same filing date as the present application;   Application 10011458-1, “Damped Longitudinal Mode Optical Latching Relay”, and having the same filing date as the present application;   Application 10011459-1, “Damped Longitudinal Mode Latching Relay”, and having the same filing date as the present application;   Application 10020013-1, titled “Switch and Method for Producing the Same”, filed Dec. 12, 2002 and identified by Ser. No. 10/317,963;   Application 10020027-1, titled “Piezoelectric Optical Relay”, filed Mar. 28, 2002 and identified by Ser. No. 10/109,309;   Application 10020071-1, titled “Electrically Isolated Liquid Metal Micro-Switches for Integrally Shielded Microcircuits”, filed Oct. 8, 2002 and identified by Ser. No. 10/266,872;   Application 10020073-1, titled “Piezoelectric Optical Demultiplexing Switch”, filed Apr. 10, 2002 and identified by Ser. No. 10/119,503;   Application 10020162-1, titled “Volume Adjustment Apparatus and Method for Use”, filed Dec. 12, 2002 and identified by Ser. No. 10/317,293;   Application 10020241-1, “Method and Apparatus for Maintaining a Liquid Metal Switch in a Ready-to-Switch Condition”, and having the same filing date as the present application;   Application 10020242-1, titled “A Longitudinal Mode Solid Slug Optical Latching Relay”, and having the same filing date as the present application;   Application 10020473-1, titled “Reflecting Wedge Optical Wavelength Multiplexer/Demultiplexer”, and having the same filing date as the present application;   Application 10020540-1, “Method and Structure for a Solid Slug Caterpillar Piezoelectric Relay”, and having the same filing date as the present application;   Application 10020541-1, titled “Method and Structure for a Solid Slug Caterpillar Piezoelectric Optical Relay”, and having the same filing date as the present application;   Application 10030438-1, “Inserting-finger Liquid Metal Relay”, and having the same filing date as the present application;   Application 10030440-1, “Wetting Finger Liquid Metal Latching Relay”, and having the same filing date as the present application;   Application 10030521-1, “Pressure Actuated Optical Latching Relay”, and having the same filing date as the present application;   Application 10030522-1, “Pressure Actuated Solid Slug Optical Latching Relay”, and having the same filing date as the present application; and   Application 10030546-1, “Method and Structure for a Slug Caterpillar Piezoelectric Reflective Optical Relay”, and having the same filing date as the present application.       

   TECHNICAL FIELD 
   This invention relates generally to the field of electronic devices and systems, and more specifically to electronic switching technology. 
   BACKGROUND 
   A relay or switch may be used to change an electrical signal from a first state to a second state. In general there may be more than two states. In applications that require a small switch geometry or a large number of switches within a small region, microelectronic fabrication techniques may be used to create switches with a small footprint. A semiconductor switch may be used in a variety of applications, such as industrial equipment, telecommunications equipment and control of electromechanical devices such as ink jet printers. 
   In switching applications, the use of piezoelectric technology may be used to actuate a switch. Piezoelectric materials have several unique characteristics. A piezoelectric material can be made to expand or contract in response to an applied voltage. This is known as the indirect piezoelectric effect. The amount of expansion or contraction, the force generated by the expansion or contraction, and the amount of time between successive contractions are important material properties that influence the application of a piezoelectric material in a particular application. Piezoelectric material also exhibits a direct piezoelectric effect, in which an electric field is generated in response to an applied force. This electric field may be converted to a voltage if contacts are properly coupled to the piezoelectric material. The indirect piezoelectric effect is useful in making or breaking a contact within a switching element, while the direct piezoelectric effect is useful in generating a switching signal in response to an applied force. 
   SUMMARY 
   A method and structure for an electrical switch is disclosed. According to the structure of the present invention, a liquid-filled chamber is housed within a solid material. Switch contacts within the liquid-filled chamber are coupled to the solid material, while piezoelectric elements are coupled to a plurality of membranes. The plurality of membranes are coupled to the liquid-filled chamber. The plurality of switch contacts are coupled to a plurality of liquid metal globules. According to the method of the present invention, a piezoelectric element is actuated, causing a membrane element to be deflected. The deflection of the membrane element increases pressure of actuator liquid and the increase in pressure of the actuator liquid breaks a liquid metal connection between a first contact and a second contact of the electrical switch. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features of the invention believed to be novel are set forth with particularity in the appended claims. The invention itself however, both as to organization and method of operation, together with objects and advantages thereof, may be best understood by reference to the following detailed description of the invention, which describes certain exemplary embodiments of the invention, taken in conjunction with the accompanying drawings in which: 
       FIG. 1  is a side view of a pusher mode liquid metal switch, according to certain embodiments of the present invention. 
       FIG. 2  is a cross sectional drawing of a pusher mode liquid metal switch, according certain embodiments of the present invention. 
       FIG. 3  is a top view of a circuit substrate layer of a pusher mode liquid metal switch, according to certain embodiments of the present invention. 
       FIG. 4  is a top view of a liquid metal channel layer of a pusher mode liquid metal switch, according to certain embodiments of the present invention. 
       FIG. 5  is a top view of a membrane layer of a pusher mode liquid metal switch, according to certain embodiments of the present invention. 
       FIG. 6  is a top view of an actuator fluid reservoir layer of a pusher mode liquid metal switch, according to certain embodiments of the present invention. 
       FIG. 7  is a bottom view of a piezoelectric substrate layer of a pusher mode liquid metal switch, according to certain embodiments of the present invention. 
   

   DETAILED DESCRIPTION 
   While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail specific embodiments, with the understanding that the present disclosure is to be considered as an example of the principles of the invention and not intended to limit the invention to the specific embodiments shown and described. In the description below, like reference numerals are used to describe the same, similar or corresponding parts in the several views of the drawings. 
   A liquid metal switch may be represented using a plurality of layers, wherein the plurality of layers represent layers created during a fabrication of the liquid metal switch. 
   Referring now to  FIG. 1  a side view  100  of a pusher mode liquid metal switch  105  is shown, according to certain embodiments of the present invention. The pusher mode liquid metal switch  105  may be composed of a plurality of distinct layers, wherein the plurality of layers provide a plurality of functions. A piezoelectric substrate layer  110  is coupled to an actuator fluid reservoir layer  120 . The actuator fluid reservoir layer  120  is coupled to membrane layer  130 , while membrane layer  130  is coupled to liquid metal channel layer  140 . Liquid metal channel layer  140  is further coupled to circuit substrate layer  150 . It is noted that circuit substrate layer  150  may further comprise a plurality of circuit traces, wherein the plurality of circuit traces are not shown in  FIG. 1 . It is noted that one or more of the layers shown in  FIG. 1  could be combined for otherwise named without departing from the spirit and scope of the present invention. As an example, membrane layer  130  and liquid metal channel layer  140  could be further combined into a channel layer, wherein the channel layer comprises a membrane and a channel. It is also noted that one or more additional layers could be present without departing from the spirit and scope of the present invention. In certain embodiments of the present invention, the piezoelectric substrate layer  110 , actuator fluid reservoir layer  120 , membrane layer  130 , liquid metal channel layer  140 , and circuit substrate layer  150  may be composed of one or more of glass, ceramic, composite material and ceramic-coated material. 
   Referring now to  FIG. 2  a cross-sectional drawing  200  of pusher mode liquid metal switch  105  is shown, according to certain embodiments of the present invention. Cross-sectional drawing  200  illustrates piezoelectric substrate layer  110  coupled to a plurality of contacts  210 , wherein the plurality of contacts  210  are coupled to a plurality of vias  225 . Plurality of vias  225  allow an electrical potential to be applied to a corresponding plurality of piezoelectric elements  215 . The electrical potential may be applied using two contacts of the plurality of contacts  210 . The two contacts are insulated by the use of a dielectric of plurality of dielectrics  220 . The dielectric of the plurality of dielectrics  220  is coupled to each pair of contacts of the plurality of contacts  210 , as illustrated in  FIG. 2 . In certain embodiments of the present invention, the plurality of dielectrics  220 , plurality of piezoelectric elements  215 , and a segment of each contact of the plurality of contacts  210  are located in actuator fluid reservoir layer  120 . In certain embodiments of the present invention, pusher element  227  is comprised of a piezoelectric element of the plurality of piezoelectric elements  215 , a dielectric of the plurality of dielectrics  220 , and a segment of a contact of the plurality of contacts  210 . 
   Pusher element  227  resides in the actuator fluid reservoir layer  120 . Pusher element  227  is separated from an adjacent pusher element by the use of actuating fluid  205 . In certain embodiments of the present invention, each pusher element in actuator fluid reservoir layer  120  is separated by actuating fluid  205 . In certain embodiments of the present invention, actuating fluid  205  is composed of an inert, low viscosity, high-boiling fluid such as 3M Fluorinert. A forward electric potential is operable to elongate a piezoelectric element of the plurality of piezoelectric elements  215 , while a reverse electric potential is operable to shorten a piezoelectric element of the plurality of piezoelectric elements  215 . It is noted that a forward electric potential could be used to shorten a piezoelectric element, while a reverse electric potential could be used to elongate a piezoelectric element without departing from the spirit and scope of the present invention. Pusher element  227  is coupled to membrane layer  130  as shown in  FIG. 2 , so that an elongation of pusher element  227  pushes on membrane layer  130  thereby causing switching fluid  230  to expand from the membrane layer  130  into a channel  240  of the liquid metal channel layer  140 . 
   Channel  240  comprises plurality of liquid metal  235 , plurality of switch contacts  245 , and switching fluid  230 . The liquid metal  235 , such as mercury or a Gallium alloy, acts as a friction-reducing lubricant. The plurality of liquid metal  235  are coupled to plurality of switch contacts  245 , and one of the plurality of liquid metal  235  is coupled to two of the plurality of switch contacts  245 . The plurality of switch contacts  245  are further coupled to circuit substrate layer  150 . 
   Pusher mode liquid metal switch  105  operates by means of an applied electric potential to two contacts of the plurality of contacts  210 . The applied electric potential causes a piezoelectric element of the plurality of piezoelectric elements to elongate. This elongation increases a pressure of switching fluid  230 . Switching fluid  230  is then forced into chamber  240 . A corresponding increase of a pressure of switching fluid  230  in chamber  240  causes a liquid metal, currently coupled to a first switch contact and a second switch contact of the plurality of switch contacts  245 , of the plurality of liquid metal  235  to separate into two distinct regions where a first region is coupled to the first switch contact of the plurality of switch contacts  245  and a second region is coupled to the second switch contact of the plurality of switch contacts  245 . In certain embodiments of the present invention, the liquid metal separates so that the second region is coupled to the second switch contact and a third switch contact of the plurality of switch contacts  245 . The separation of the liquid metal of the plurality of liquid metal  235  is operable to change a value of the pusher mode liquid metal switch  105  from a first state to a second state. It is noted in certain embodiments of the present invention, the separation of the liquid metal is operable to be used to change a state of pusher mode liquid metal switch  105  without the use of the third switch contact. The liquid metal is maintained in a coupling to the second switch contact and the third switch contact by a surface tension between the liquid metal and a corresponding surfaces of the second switch contact and the third switch contact. 
   It is also noted that two pusher elements could be used so that a first pusher element separates a liquid metal of the plurality of liquid metal  235  coupled to the first switch contact and the second switch contact and a liquid metal is then coupled to the second switch contact and the third switch contact. A second pusher element could then be used to separate the liquid metal coupled to the second switch contact and the third switch contact. In certain embodiments of the present invention, the first pusher element could be made to push (elongate), while the second pusher element could be made to pull (shorten) so that the liquid metal is pushed by the first pusher element while the second pusher element creates a negative pressure to pull the liquid metal apart. 
   Referring now to  FIG. 3  a first top view  300  of the circuit substrate layer  110  of the pusher mode liquid metal switch  105  is shown, according to certain embodiments of the present invention. The first top view  300  illustrates the arrangement of the plurality of contacts  210 . Although plurality of contacts  210  are represented as having a square top profile, other profiles, such as circular, could be used without departing from the spirit and scope of the present invention. 
   Referring now to  FIG. 4  a top view  400  of the liquid metal channel layer  140  of the pusher mode liquid metal switch  105  is shown, according to certain embodiments of the present invention. The top view  400  illustrates a top view  415  of channel  240  showing a plurality of through holes  405 , wherein plurality of through holes  405  are operable to enable switching fluid  230  to pass more forcefully into channel  240 . Plurality of through holes  405  are sized so that a pressure of switching fluid  230  is increased, thereby enhancing a separation of a liquid metal of the plurality of liquid metals  235 . A sectional view  410  of liquid metal channel layer  140  is also shown. The sectional view  410  illustrates a width of plurality of through holes  405  relative to a width of channel  240 . It is noted that although two through holes are shown in  FIG. 4 , a greater number of through holes could be used without departing from the spirit and scope of the present invention. It is also noted that the plurality of through holes  405  are operable to have a plurality of distinct widths. The plurality of distinct widths may be chosen to match an amount of switching fluid  230  and an amount of elongation or shortening of plurality of piezoelectric elements  215 . 
   Referring now to  FIG. 5  a top view  500  of the membrane layer  130  of the pusher mode liquid metal switch  105  is shown, according to certain embodiments of the present invention. The top view  500  illustrates an orientation of membrane layer  130  that includes a view of fluid flow restrictors  510 . Fluid flow restrictors  510  are operable to control an amount of switching fluid  230  that flows into actuation fluid reservoir layer  120 . Fluid flow restrictors  510  are sized so that adequate pressure is transferred to a liquid metal of plurality of liquid metals  235  while still providing a sufficient amount of switching fluid  230 . A sectional view  505  illustrates an orientation of fluid flow restrictors  510  with respect to plurality of membranes  515 . 
   Referring now to  FIG. 6 , a top view  600  of actuator fluid reservoir layer  120  of the pusher mode liquid metal switch  105  is shown, according to certain embodiments of the present invention. The top view  600  illustrates a size of a reservoir  610  containing actuating fluid  230 . A sectional view  605  further illustrates a geometric shape of reservoir  610 . 
   Referring now to  FIG. 7  a bottom view  700  of piezoelectric substrate layer  110  of the pusher mode liquid metal switch  105  is shown, according to certain embodiments of the present invention. The bottom view  700  illustrates an orientation of plurality of actuators  227 . Sectional view  705  further shows the orientation of a contact of the plurality of contacts  210 . Also shown in  FIG. 7  is fill port  710 . Fill port  710  is operable to be used to fill reservoir  610  with actuating fluid  205 . In certain embodiments of the present invention, actuating fluid  205  is filled during assembly of pusher mode liquid metal switch  105 , after which fill port  710  is sealed. 
   While the invention has been described in conjunction with specific embodiments, it is evident that many alternatives, modifications, permutations and variations will become apparent to those of ordinary skill in the art in light of the foregoing description. Accordingly, it is intended that the present invention embrace all such alternatives, modifications and variations as fall within the scope of the appended claims.