Patent Grant
8174343
The present invention relates to relays. More specifically, the present invention relates to electromechanical relays and to methods of making electromechanical relays.
Relays are electromechanical switches operated by a flow of electricity in one circuit and controlling the flow of electricity in another circuit. A typical relay consists basically of an electromagnet with a soft iron bar, called an armature, held close to it. A movable contact is connected to the armature in such a way that the contact is held in its normal position by a spring. When the electromagnet is energized, it exerts a force on the armature that overcomes the pull of the spring and moves the contact so as to either complete or break a circuit. When the electromagnet is de-energized, the contact returns to its original position. Variations on this mechanism are possible: some relays have multiple contacts; some are encapsulated; some have built-in circuits that delay contact closure after actuation; some, as in early telephone circuits, advance through a series of positions step by step as they are energized and de-energized, and some relays are of latching type.
Relays are classified by their number of poles and number of throws. The pole of a relay is the terminal common to every path. Each position that the pole can connect to is called a throw. A relay can be made of n poles and m throws. For example, a single-pole-single-throw relay (SPST) has one pole and one throw. A single-pole-double-throw (SPDT) relay has one pole and two throws. A double-pole-double-throw (DPDT) relay has two poles, each with two simultaneously controlled throws.
Relays are then classified into forms. Relay forms are categorized by the number of poles and throws as well as the default position of the relay. Three common relay forms are: A, B, and C. Form A relays are SPST with a default state of normally open. Form B relays are SPST with a default state of normally closed. Form C relays are SPDT and break the connection with one throw before making contact with the other (break-before-make).
Latching relays are the types of relays which can maintain closed and open contact positions without energizing an electromagnet. Short current pulses are used to temporally energize the electromagnet and switch the relay from one contact position to the other. An important advantage of latching relays is that they do not consume power (actually they do not need a power supply) in the quiescent state.
Conventional electromechanical relays have traditionally been fabricated one at a time, by either manual or automated processes. The individual relays produced by such an “assembly-line” type process generally have relatively complicated structures and exhibit high unit-to-unit variability and high unit cost. Conventional electromechanical relays are also relatively large when compared to other electronic components. Size becomes an increasing concern as the packaging density of electronic devices continues to increase.
Many designs and configurations have been used to make latching electromechanical relays. Two forms of conventional latching relays are described in the Engineers' Relay Handbook (Page 3-24, Ref. [1]). A permanent magnet supplies flux to either of two permeable paths that can be completed by an armature. To transfer the armature and its associated contacts from one position to the other requires energizing current through the electromagnetic coil using the correct polarity. One drawback of these traditional latching relay designs is that they require the coil to generate a relatively large reversing magnetic field in order to transfer the armature from one position to the other. This requirement mandates a large number of wire windings for the coil, making the coil size large and impossible or very difficult to fabricate other than using conventional winding methods.
A non-volatile programmable switch is described in U.S. Pat. No. 5,818,316 issued to Shen et al. on Oct. 6, 1998, the entirety of which is incorporated herein by reference. The switch disclosed in this reference includes first and second magnetizable conductors having first and second ends, respectively, each of which is a north or south pole. The ends are mounted for relative movement between a first position in which they are in contact and a second position in which they are insulated from each other. The first conductor is permanently magnetized and the second conductor is switchable in response to a magnetic field applied thereto. Programming means are associated with the second conductor for switchably magnetizing the second conductor so that the second end is alternatively a north or south pole. The first and second ends are held in the first position by magnetic attraction and in the second position by magnetic repulsion.
Another latching relay is described in U.S. Pat. No. 6,469,602 B2 issued to Ruan et al. on Oct. 22, 2002 (claiming priority established by the Provisional Application No. 60/155,757, filed on Sep. 23, 1999), the entirety of which is incorporated herein by reference. The relay disclosed in this reference is operated by providing a movable body sensitive to magnetic fields such that the movable body exhibits a first state corresponding to the open state of the relay and a second state corresponding to the closed state of the relay. A first magnetic field may be provided to induce a magnetic torque in the movable body, and the movable body may be switched between the first state and the second state with a second magnetic field that may be generated by, for example, a conductor formed on a substrate with the relay.
Yet another non-volatile micro relay is described in U.S. Pat. No. 6,124,650 issued to Bishop et al. on Sep. 26, 2000, the entirety of which is incorporated herein by reference. The device disclosed in this reference employs square-loop latchable magnetic material having a magnetization direction capable of being changed in response to exposure to an external magnetic field. The magnetic field is created by a conductor assembly. The attractive or repulsive force between the magnetic poles keeps the switch in the closed or open state.
Each of the prior arts, though providing a unique approach to make latching electromechanical relays and possessing some advantages, has some drawbacks and limitations. Some of them may require large current for switching, and some may require precise relative placement of individual components. These drawbacks and limitations can make manufacturing difficult and costly, and hinder their value in practical applications.
Accordingly, it would be highly desirable to provide an easily switchable electromechanical relay which is also simple and easy to manufacture and use.
It is a purpose of the present invention to provide a new and improved method to make such electromechanical relays.
The above problems and others are at least partially solved and the above purposes and others are realized in a relay comprising a movable body placed in a cavity which is formed on a substrate, surrounded by a spacer layer and sealed by a cover layer. The movable body comprises a first magnet which is permanently magnetized and has at least a first end. A nearby switching electromagnet, when energized, produces a switching magnetic field which is primarily perpendicular to the magnetization direction of the first magnet and exerts a magnetic torque on the first magnet to force the first magnet and said movable body to rotate and closes an electrical conduction path at the first end. Changing the direction of the electrical current in the switching electromagnet changes the direction of the switching magnetic field and thus the direction of the magnetic torque on the first magnet, and causes the first magnet to rotate in an opposite direction and opens the electrical conduction path at the first end. The first magnet can comprise multiple magnetic layers to form relatively closed magnetic circuits with other magnetic components. Latching and non-latching types of relays can be formed by appropriately using soft and permanent magnets as various components.
The above and other features and advantages of the present invention are hereinafter described in the following detailed description of illustrative embodiments to be read in conjunction with the accompanying figures, wherein like reference numerals are used to identify the same or similar parts in the similar views, and:
It should be appreciated that the particular implementations shown and described herein are examples of the invention and are not intended to otherwise limit the scope of the present invention in any way. Indeed, for the sake of brevity, conventional electronics, manufacturing, and other functional aspects of the systems (and components of the individual operating components of the systems) may not be described in detail herein. Furthermore, for purposes of brevity, the invention is frequently described herein as pertaining to an electromagnetic relay for use in electrical or electronic systems. It should be appreciated that many other manufacturing techniques could be used to create the relays described herein, and that the techniques described herein could be used in mechanical relays, optical switches, fluidic control systems, or any other switching devices. Further, the techniques would be suitable for application in electrical systems, optical systems, consumer electronics, industrial electronics, wireless systems, space applications, fluidic control systems, medical systems, or any other application. Moreover, it should be understood that the spatial descriptions made herein are for purposes of illustration only, and that practical latching relays may be spatially arranged in any orientation or manner. Arrays of these relays can also be formed by connecting them in appropriate ways and with appropriate devices.
Movable body 10 comprises a first magnet 11, flexure spring and support 12, and electrical contacts 13 and 14. Movable body 10 is further supported by a pivot 15. First magnet 11 comprises a permanent (hard) magnetic layer and is permanently magnetized primarily along the positive x-axis when said first magnet 11 lies leveled. Other magnetization orientation of first magnet 11 is also possible as long as it achieves the function and purpose of this invention. Movable body 10 has a first (right) end associated with the first (right) end of first magnet 11 and contact 13, and has a second (left) end associated with the second (left) end of first magnet 11 and contact 14. Said permanent (hard) magnetic layer can be any type of hard magnetic material that can retain a remnant magnetization in the absence of an external magnetic field and its remnant magnetization cannot be easily demagnetized. In an exemplary embodiment, said permanent magnetic layer is a SmCo permanent magnet with an approximate remnant magnetization (Br=μ0M) of about 1 T predominantly along the positive x-axis when it lies leveled. Other possible hard magnetic materials are, for example, NdFeB, AlNiCo, Ceramic magnets (made of Barium and Strontium Ferrite), CoPtP alloy, and others, that can maintain a remnant magnetization (Br=μ0M) from about 0.001 T (10 Gauss) to above 1 T (104 Gauss), with coercivity (Hc) from about 7.96×102 A/m (10 Oe) to above 7.96×105 A/m (104 Oe). First magnet 11 has a combined magnetic moment m predominantly along the positive x-axis when first magnet 11 lies leveled. Flexure spring and support 12 can be any flexible material that on one hand supports movable body 10 and on the other allows movable body 10 to be able to move and rotate. Flexure spring and support 12 can be made of metal layers (such as Beryllium Copper, Ni, NiFe, stainless steel, etc.), or non-metal layers (such as polyimide, Si, Si3Ni4, etc.). The flexibility of the flexure spring 12 can be adjusted by its thickness, width, length, shape, and elasticity, etc. Pivot 15 further supports movable body 10 to maintain a gap between movable body 10 and substrate 33. Pivot 15 can be placed on the top of movable body 10 to maintain a gap between movable body 10 and soft magnetic layer 32. Electrical contacts 13 and 14 can be any electrically conducting layer such as Au, Ag, Rh, Ru, Pd, AgCdO, Tungsten, etc., or suitable alloys. Electrical contacts 13 and 14 can be formed onto the tips (ends) of movable body 10 by electroplating, deposition, soldering, welding, lamination, screen printing, melting, evaporation, or any other suitable means. Flexure spring and support 12 and electrical contacts 13 and 14 can be formed by either using one process and the same material, or by using multiple processes, multiple layers, and different materials. When movable body 10 rotates and its two ends move up or down, electrical contact 13 (or 14) either makes or breaks the electrical connection with the bottom contact 41 (or 42). Optional insulating layers (not shown) can be placed between the conducting layers to isolate electrical signals in some cases.
Coil 20 (switching electromagnet) is formed by having multiple windings of conducting wires around movable body 10. The conducting wires can be any conducting materials such as Cu, Al, Au, Ag, or others. The windings can be formed by either winding the conducting wires around a bobbin, or by electroplating, deposition, screen printing, etching, laser forming, or other means used in electronics industry (e.g., semiconductor integrated circuits, printed circuit boards, multi-layer ceramic electronic devices, etc.). One purpose of coil 20 in relay 100, when energized, is to provide a switching vertical (along y-axis) magnetic field (Hs) so that a magnetic torque (τ=μ0m×Hs) can be created on movable body 10. Because the magnetic moment m in first magnet 11 is fixed, the direction and magnitude of the torque depends on the direction and magnitude of the current in coil 20. This arrangement provides a means for external electronic control of the relay switching between different states, as to be explained in detail below.
Soft magnetic layers 31 (second magnet) and 32 can be any magnetic material which has high permeability (e.g., from about 100 to above 105) and can easily be magnetized by the influence of an external magnetic field. Examples of these soft magnetic materials include permalloy (NiFe alloys), Iron, Silicon Steels, FeCo alloys, soft ferrites, etc. One purpose of soft magnetic layers 31 and 32 is to form a closed magnetic circuit and enhance the coil-induced magnetic flux density (switching vertical magnetic field Hs) in the movable body region. Another purpose of soft magnetic layers 31 and 32 is to cause an attractive force between a pole of first magnetic layer 11 and the induced local opposite magnetic pole of the soft magnetic layer so that a stable contact force can be maintained between electrical contact 13 (or 14) and electrical contact 41 (or 42) when the latching feature is desired. Yet another purpose of soft magnetic layers 31 and 32 is to confine the magnetic field inside cavity 36 enclosed by soft magnetic layers 31 and 32 so that the magnetic interference between adjacent devices can be eliminated or reduced. The distance between soft magnetic layer 31 (or 32) and first magnet 11 can be adjusted to alter the attractive force between the magnetic poles of magnet 11 and the soft magnetic layer 31 (or 32). Openings can also be suitably formed in soft magnetic layers 31 and 32 to achieve the same purpose.
Electrical contacts 41 and 42 can be any electrically conducting layer such as Au, Ag, Rh, Ru, Pd, AgCdO, Tungsten, etc., or suitable alloys. Electrical contacts 41 and 42 can be formed on substrate 33 by electroplating, deposition, screen printing, welding, lamination, melting, evaporation, firing, or any other suitable means. Optional insulating layers (not shown) can be placed between the conducting layers to isolate electrical signals in some cases. Transmission-line types of contacts and metal traces can also be suitably designed and formed for high performance radio-frequency applications.
Substrate 33 can be any suitable structural material (plastic, ceramics, semiconductors, metal coated with thin films, glass, etc.).
Spacer 35 can be any suitable structural material (plastic, ceramics, semiconductors, metal coated with thin films, glass, etc.). Spacer 35 is provided so that cavity 36 can be formed to house movable body 10. Spacer 35 can be formed as a single layer together with coil 20 as shown, or as a separate layer. In this exemplary embodiment, multiple layers of metal traces are printed on a dielectric layer (e.g., ceramic material) and stacked together and co-fired to form coil 20 and spacer 35. The metal traces on adjacent layers are joined from head to tail so that current can flow in a consistent manner (either all clockwise or all counterclockwise).
Cover 34 can be any suitable structural material (plastic, ceramics, semiconductors, metal, glass, etc.) and is provided to seal cavity 36 and to protect movable body 10 and various electrical contacts from outside environment. In this exemplary embodiment (relay 100), cover 34 is formed together with coil 20 and spacer 35 as a unitary body.
Adhesion layer 70 can be any suitable material (glue, epoxy, glass frit, solder, melted metal, paste, etc.) which bonds two interfaces together so that two bodies can be joined. Adhesion layer 70 can be pre-formed on the surfaces of the joining bodies or applied as an individual layer between the two joining interfaces. To promote strong adhesion, a physical (heat, pressure, etc.) or chemical (cross-link, etc.) process is caused to occur in adhesion layer 70 when forming the bond.
Via 53 can be any suitable conducting material (Au, Ag, Cu, Pd, Pt, Tungsten, Al, etc.) which is formed in some openings through various layers (e.g., substrate 33, coil 20, cover 34, etc.) to facilitate electrical connection between metal pads on different surfaces.
Side trace 60 can be any suitable conducting material (Au, Ag, Cu, Pd, Pt, Tungsten, Al, etc.) which is formed on the sides of relay 100 to facilitate electrical connection between metal pads on different surfaces.
Pad 50 can be any suitable conducting material (Au, Ag, Cu, Pd, Pt, Tungsten, Al, etc.) which is formed on the outside surface of relay 100 to serve as electrical terminals. Pad 50 can be coated with suitable soldering material to facilitate soldering on a printed circuit board.
Alignment features 720 (fiducial marks or registration holes) are placed on various layers for alignment purposes during assembly.
In a broad aspect of the invention, an electromagnet 20, when energized, produces a switching magnetic field which is primarily perpendicular to the magnetization direction of first movable magnet 11 and exerts a magnetic torque on first magnet 11 to force first magnet 11 and movable body 10 to rotate and close an electrical conduction path at one end (e.g., first end) of movable body 10. Changing the direction of the electrical current in switching electromagnet 20 changes the direction of the switching magnetic field and thus the direction of the magnetic torque on first magnet 11, and causes first magnet 11 and movable body 10 to rotate in an opposite direction and opens the electrical conduction path at the end (e.g., first end) of movable body 10 and closes the electrical conduction path at the other end (e.g., second end).
With continued reference to
Many methods can be used to make aforementioned exemplary relays. A few examples are provided below.
With reference to
With reference to
With reference to
It is understood that a variety of methods can be used to fabricate the electromechanical relay. These methods include, but not limited to, semiconductor integrated circuit fabrication methods, printed circuit board fabrication methods, micro-machining methods, co-fired ceramic processes, and so on. The methods include processes such as photo lithography for pattern definition, deposition, plating, screen printing, etching, lamination, molding, welding, adhering, bonding, and so on. The detailed descriptions of various possible fabrication methods are omitted here for brevity.
It will be understood that many other embodiments and combinations of different choices of materials and arrangements could be formulated without departing from the scope of the invention. Similarly, various topographies and geometries of the electromechanical relay could be formulated by varying the layout of the various components.
The corresponding structures, materials, acts and equivalents of all elements in the claims below are intended to include any structure, material or acts for performing the functions in combination with other claimed elements as specifically claimed. Moreover, the steps recited in any method claims may be executed in any order. The scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given above.
This patent application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/165,460, filed on Mar. 31, 2009, which is hereby incorporated by reference. This application is a continuation-in-part of U.S. application Ser. No. 11/534,655, filed on Sep. 24, 2006, now U.S. Pat. No. 7,482,899 B2 issued on Jan. 27, 2009, which is incorporated herein by reference in its entirety.
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| Number | Date | Country | |
|---|---|---|---|
| 20100182110 A1 | Jul 2010 | US |
| Number | Date | Country | |
|---|---|---|---|
| 61165460 | Mar 2009 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11534655 | Sep 2006 | US |
| Child | 12748470 | US |
