The invention relates to the field of switching relays, and in particular to a piezoelectrically actuated relay that latches by means of liquid surface tension.
Communications systems using optical signals require the use of optical switches and routers. An early approach to optical switching was to convert the optical signal to an electrical signal, use an electrical switch or router and then convert back to an optical signal. More recently, optical relays have been used in which an electrical control signal is used to control the switching or routing of an optical signal. Optical relays typically switch optical signals by using movable solid mirrors or by using the creation of vapor bubbles to alter the index of refraction inside a cavity. The moveable mirrors may use electrostatic latching mechanisms, whereas bubble switches do not latch. Piezoelectric latching relays either use residual charges in the piezoelectric material to latch, or actuate switch contacts containing a latching mechanism.
Liquid metal is also used in electrical relays. A liquid metal droplet can be moved by a variety of techniques, including electrostatic forces, variable geometry due to thermal expansion/contraction, and pressure gradients. When the dimension of interest shrinks, the surface tension of the liquid metal becomes the dominant force over other forces, such as body forces (inertia). Consequently, some micro-electromechanical (MEM) systems utilize liquid metal switching.
The present invention relates to a switch in which a liquid metal droplet is moved within a channel and used to block or unblock a signal path passing through the channel. The liquid metal droplet is moved by piezoelectric elements acting on a diaphragm to create a pressure changes in the channel. The liquid metal droplet adheres to wettable metal contact pads within the channel to provide a latching mechanism.
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:
While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail one or more specific embodiments, with the understanding that the present disclosure is to be considered as exemplary 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.
The present invention relates to a piezoelectrically actuated relay that switches and latches by means of a liquid metal droplet moving within a switching channel. In an exemplary embodiment, the relay uses piezoelectric elements, operating in a bending mode, to deform a diaphragm and displace an actuation fluid that in turn displaces the liquid metal. Magnetorestrictive elements, such as Terfenol-D, that deform in the presence of a magnetic field may be used as an alternative to piezoelectric elements. In the sequel, piezoelectric elements and magnetorestrictive elements will be collectively referred to as “piezoelectric elements”.
The liquid metal blocks or unblocks an optical path, allowing the switching of optical signals. The liquid metal, which may be mercury, wets at least one fixed contact pad on the relay housing and is held in place by surface tension. It is noted that a switching of one or more electrical signals is also possible, wherein the switching of the one or more electrical signals may be accomplished by coupling the one or more electrical signals to one or more contact pads. The liquid metal coupling to two of the one or more contact pads may be used to effectively select an electrical signal of the one or more electrical signals. The switching of the one or more electrical signals and the switching of the optical signals may be facilitated by the use of a slug coupled to the liquid metal. In an exemplary embodiment of switching the one or more electrical signals, the slug and the liquid metal is coupled to two of the one or more contact pads so that an electrical signal path is completed that is operable to switch an electrical signal of the one or more electrical signals. In an exemplary embodiment of switching the one or more optical signals, the slug and the liquid metal are operable to block or unblock one or more of the optical signals.
In one embodiment, micro-machining techniques are used to manufacture the relay. An end view of an optical relay 100 is shown in FIG. 1. In this embodiment, the body of the relay is made up of six layers and is amenable to manufacture by micro-machining. The lowest layer is a bottom cap layer 102 containing a reservoir of actuation fluid. The next layer is a pump chamber layer 104 that incorporates the diaphragms and pump chambers of the piezoelectric pumps. The next layer is a via layer 106 containing ducts (vias) that couple the pump chambers to the switching channel. Switching of the optical signal occurs in a switching channel contained in the switching layer 108. In a first mode of operation, an optical signal enters the relay through an optical fiber or waveguide 110 and, if not blocked in the relay, exits through optical fiber or waveguide 112. The final layer is a top cap layer 114.
A view of the optical relay with the top cap layer removed is shown in FIG. 3. The switching layer 108 is positioned above the via layer 106. An optical waveguide 110, embedded in a notch 130 in the switching layer 108, is optically aligned with the optical waveguide 112 (embedded in a notch 132). For light to couple between the waveguides 110 and 112 it must pass through the transparent actuation fluid in the switching channel 128. Optical waveguide 140, embedded in a notch 142 in the switching layer 108, is optically aligned with the optical waveguide 144 (embedded in a notch 146). A central droplet of liquid metal 148 is positioned within the switching channel 128 and is held in wetted contact with the contact pad 154. In an exemplary embodiment, the liquid metal is mercury. The central liquid metal droplet 148 may be moved to coalesce with one of the further liquid metal droplets 150 and 152. The liquid metal droplets 150 and 152 are in wetted contact with contact pads 134 and 156, respectively. The total volume of liquid metal is chosen so that only two volumes coalesce at one time. The contact pads may be made of seal belt metal, for example. Each belt is made up of four elements, two attached to the switching layer 108, one attached to the top of via layer 106 and one attached to the underside of the top cap layer 114. Surface tension in the liquid metal droplets resists motion of the liquid. When the liquid metal droplets 148 and 152 are coalesced, as shown in
Motion of the liquid droplets is controlled by a transparent, inert, electrically non-conducting actuation fluid that fills the interior of the relay surrounding the liquid metal droplets. The actuation fluid is pumped into or out of the switching channel 128 through vias or ducts positioned between the contact pads. The central droplet of liquid metal 148 can be separated from droplet 152 by pumping actuation fluid into the switching channel through the duct 158 shown in FIG. 4. Optionally, fluid may simultaneously be pumped out of the switching channel through the via 126 (in FIG. 3). The resulting pressure moves the central liquid metal droplet 148 to the right, as shown in
A side view of the switching layer 108 is shown in FIG. 13. The optical waveguides 110 and 140 are imbedded in triangular notches 130 and 142 in the top surface of the layer. The use of notches allows for accurate optical alignment of the waveguides during assembly of the relay.
The optical relay of the present invention can be made using micro-machining techniques for small size.
One advantage of the use of piezoelectric elements is that they are capacitive devices and store energy rather than dissipating it. As a result, power consumption and heat build up is kept to a minimum.
In a further embodiment, a single piezoelectric pump is used. The pump is operable to pump actuation fluid into the switching channel to push the central liquid metal droplet in one direction and to pump actuation fluid out of the switching channel to pull the central liquid metal droplet in the other direction.
If two piezoelectric pumps are used, they may push alternately, pull alternately, or one may push while the other pulls and vice versa.
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.
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 10010656-1, titled “A Longitudinal Mode Optical Latching Relay”, and having the same filing date as the present application; Application 10010663-1, “Method and Structure for a Pusher-Mode Piezoelectrically Actuated Liquid Metal Switch”, 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.
Number | Name | Date | Kind |
---|---|---|---|
2312672 | Pollard, Jr. | Mar 1943 | A |
2564081 | Schilling | Aug 1951 | A |
3430020 | Tomkewitsch et al. | Feb 1969 | A |
3529268 | Rauterberg | Sep 1970 | A |
3600537 | Twyford | Aug 1971 | A |
3639165 | Rairden, III | Feb 1972 | A |
3657647 | Beusman et al. | Apr 1972 | A |
4103135 | Gomez et al. | Jul 1978 | A |
4200779 | Zakurdaev et al. | Apr 1980 | A |
4238748 | Goullin et al. | Dec 1980 | A |
4245886 | Kolodzey et al. | Jan 1981 | A |
4336570 | Brower | Jun 1982 | A |
4419650 | John | Dec 1983 | A |
4434337 | Becker | Feb 1984 | A |
4475033 | Willemsen et al. | Oct 1984 | A |
4505539 | Auracher et al. | Mar 1985 | A |
4582391 | Legrand | Apr 1986 | A |
4628161 | Thackrey | Dec 1986 | A |
4652710 | Karnowsky et al. | Mar 1987 | A |
4657339 | Fick | Apr 1987 | A |
4742263 | Harnden et al. | May 1988 | A |
4786130 | Georgiou et al. | Nov 1988 | A |
4797519 | Elenbaas | Jan 1989 | A |
4804932 | Akanuma et al. | Feb 1989 | A |
4988157 | Jackel et al. | Jan 1991 | A |
5278012 | Yamanaka et al. | Jan 1994 | A |
5415026 | Ford | May 1995 | A |
5502781 | Li et al. | Mar 1996 | A |
5644676 | Blomberg et al. | Jul 1997 | A |
5675310 | Wojnarowski et al. | Oct 1997 | A |
5677823 | Smith | Oct 1997 | A |
5751074 | Prior et al. | May 1998 | A |
5751552 | Scanlan et al. | May 1998 | A |
5828799 | Donald | Oct 1998 | A |
5841686 | Chu et al. | Nov 1998 | A |
5849623 | Wojnarowski et al. | Dec 1998 | A |
5874770 | Saia et al. | Feb 1999 | A |
5875531 | Nellissen et al. | Mar 1999 | A |
5886407 | Polese et al. | Mar 1999 | A |
5889325 | Uchida et al. | Mar 1999 | A |
5912606 | Nathanson et al. | Jun 1999 | A |
5915050 | Russell et al. | Jun 1999 | A |
5972737 | Polese et al. | Oct 1999 | A |
5994750 | Yagi | Nov 1999 | A |
6021048 | Smith | Feb 2000 | A |
6180873 | Bitko | Jan 2001 | B1 |
6201682 | Mooij et al. | Mar 2001 | B1 |
6207234 | Jiang | Mar 2001 | B1 |
6212308 | Donald | Apr 2001 | B1 |
6225133 | Yamamichi et al. | May 2001 | B1 |
6278541 | Baker | Aug 2001 | B1 |
6304450 | Dibene, II et al. | Oct 2001 | B1 |
6320994 | Donald et al. | Nov 2001 | B1 |
6323447 | Kondoh | Nov 2001 | B1 |
6351579 | Early et al. | Feb 2002 | B1 |
6356679 | Kapany | Mar 2002 | B1 |
6373356 | Gutierrez | Apr 2002 | B1 |
6396012 | Bloomfield | May 2002 | B1 |
6396371 | Streeter et al. | May 2002 | B2 |
6408112 | Bartels | Jun 2002 | B1 |
6446317 | Figueroa et al. | Sep 2002 | B1 |
6453086 | Tarazona | Sep 2002 | B1 |
6470106 | McClelland et al. | Oct 2002 | B2 |
6487333 | Fouquet et al. | Nov 2002 | B2 |
6501354 | Gutierrez et al. | Dec 2002 | B1 |
6512322 | Fong et al. | Jan 2003 | B1 |
6515404 | Wong | Feb 2003 | B1 |
6516504 | Schaper | Feb 2003 | B2 |
6559420 | Zarev | May 2003 | B1 |
6633213 | Dove | Oct 2003 | B1 |
20020037128 | Burger et al. | Mar 2002 | A1 |
20020146197 | Yong | Oct 2002 | A1 |
20020150323 | Nishida et al. | Oct 2002 | A1 |
20020168133 | Saito | Nov 2002 | A1 |
20030035611 | Shi | Feb 2003 | A1 |
Number | Date | Country |
---|---|---|
0593836 | Apr 1994 | EP |
2418539 | Sep 1979 | FR |
2458138 | Dec 1980 | FR |
2667396 | Apr 1992 | FR |
SHO 36-18575 | Oct 1961 | JP |
SHO 47-21645 | Oct 1972 | JP |
62-276838 | Dec 1987 | JP |
63-294317 | Dec 1988 | JP |
8-125487 | May 1996 | JP |
9161640 | Jun 1997 | JP |
WO9946624 | Dec 1999 | WO |
Number | Date | Country | |
---|---|---|---|
20040200703 A1 | Oct 2004 | US |