Electricity: magnetically operated switches – magnets – and electr – Electromagnetically actuated switches – Polarity-responsive
Reexamination Certificate
2002-01-18
2004-09-21
Donovan, Lincoln (Department: 2832)
Electricity: magnetically operated switches, magnets, and electr
Electromagnetically actuated switches
Polarity-responsive
C200S181000
Reexamination Certificate
active
06794965
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to electronic and optical switches. More specifically, the present invention relates to micro-magnetic latching switches with relaxed permanent magnet alignment requirements.
2. Background Art
Switches are typically electrically controlled two-state devices that open and close contacts to effect operation of devices in an electrical or optical circuit. Relays, for example, typically function as switches that activate or de-activate portions of electrical, optical or other devices. Relays are commonly used in many applications including telecommunications, radio frequency (RF) communications, portable electronics, consumer and industrial electronics, aerospace, and other systems. More recently, optical switches (also referred to as “optical relays” or simply “relays” herein) have been used to switch optical signals (such as those in optical communication systems) from one path to another.
Although the earliest relays were mechanical or solid-state devices, recent developments in micro-electro-mechanical systems (MEMS) technologies and microelectronics manufacturing have made micro-electrostatic and micro-magnetic relays possible. Such micro-magnetic relays typically include an electromagnet that energizes an armature to make or break an electrical contact. When the magnet is de-energized, a spring or other mechanical force typically restores the armature to a quiescent position. Such relays typically exhibit a number of marked disadvantages, however, in that they generally exhibit only a single stable output (i.e., the quiescent state) and they are not latching (i.e., they do not retain a constant output as power is removed from the relay). Moreover, the spring required by conventional micro-magnetic relays may degrade or break over time.
Another micro-magnetic relay is described in U.S. Pat. No. 5,847,631, (the '631 patent) issued to Taylor et al. on Dec. 8, 1998, the entirety of which is incorporated herein by reference. The relay disclosed in this patent includes a permanent magnet and an electromagnet for generating a magnetic field that intermittently opposes the field generated by the permanent magnet. The replay must consume power in the electromagnet to maintain at least one of the output states. Moreover, the power required to generate the opposing field would be significant, thus making the relay less desirable for use in space, portable electronics, and other applications that demand low power consumption.
The basic elements of a micro-magnetic latching switch include a permanent magnet, a substrate, a coil, and a cantilever at least partially made of soft magnetic materials. In its optimal configuration, the permanent magnet produces a static magnetic field that is relatively perpendicular to the horizontal plane of the cantilever. However, the magnetic field lines produced by a permanent magnet with a typical regular shape (disk, square, etc.) are not necessarily perpendicular to a plane, especially at the edge of the magnet. Then, any horizontal component of the magnetic field due to the permanent magnet can either eliminate one of the bistable states, or greatly increase the current that is needed to switch the cantilever from one state to the other. Careful alignment of the permanent magnet relative to the cantilever so as to locate the cantilever in the right spot of the permanent magnet field (usually near the center) will permit bi-stability and minimize switching current. Nevertheless, high-volume production of the switch can become difficult and costly if the alignment error tolerance is small.
What is desired is a bi-stable, latching switch with relaxed permanent magnet alignment requirements. Such a switch should also be reliable, simple in design, low-cost and easy to manufacture, and should be useful in optical and/or electrical environments.
BRIEF SUMMARY OF THE INVENTION
The micro-magnetic latching switches of the present invention can be used in a plethora of products including household and industrial appliances, consumer electronics, military hardware, medical devices and vehicles of all types, just to name a few broad categories of goods. The micro-magnetic latching switches ofthe present invention have the advantages of compactness, simplicity of fabrication, and have good performance at high frequencies, which lends them to many novel applications in many RF applications.
The present invention is directed to a micro magnetic latching device. The device, or switch, comprises a substrate having a moveable element supported thereon. The moveable element, or cantilever, has a long axis and a magnetic material. The device also has first and second magnets that produce a first magnetic field, which induces a magnetization in the magnetic material. The magnetization is characterized by a magnetization vector pointing in a direction along the long axis of the moveable element, wherein the first magnetic field is approximately perpendicular to a major central portion of the long axis. The device also has a coil that produces a second magnetic field to switch the movable element between two stable states, wherein only temporary application of the second magnetic field is required to change direction of the magnetization vector thereby causing the movable element to switch between the two stable states.
In one embodiment, the first magnet is a permanent magnet that is substantially planar and substantially parallel to the substrate.
In another embodiment, the first and the second magnets are permanent magnets that are substantially planar and substantially parallel to the substrate. In this embodiment the moveable element and the substrate are located between the first and the second magnets.
In another embodiment, the second magnet is a permalloy layer that is substantially planar and substantially parallel to the substrate.
In still another embodiment, the permalloy layer is located between the substrate and the movable element.
In yet another embodiment, the permalloy layer is located on an opposite side of the substrate from a side of the substrate that supports the movable element.
In a further embodiment, the movable element is located between the permalloy layer and the substrate, and the permanent magnet is located on an opposite side of the substrate from a side of the substrate that supports the movable element.
In another embodiment, the permanent magnet is located on an opposite side of the substrate from a side of the substrate that supports the movable
In still another embodiment, the device further comprises a second permalloy layer located on an opposite side of the substrate from a side of the substrate that supports the movable element.
In yet another embodiment, the movable element is located between the permalloy layer and the permanent magnet.
In another embodiment, the movable element is located between the substrate and the permanent magnet.
In still another embodiment, the device further comprises a second permalloy layer located between the permanent magnet and the moveable element.
In another embodiment, the device further comprises a second permalloy layer located on an outer side of the permanent magnet.
In yet another embodiment, the substrate comprises raised structures that support the moveable element.
In another embodiment, the device further comprises a pair of ground planes that sandwich the moveable element.
In still another embodiment, the permalloy layer comprises alternating discrete sections of soft magnetic material and sections of non-magnetic material, wherein the alternating sections are located along the long axis.
In another embodiment, the second permalloy layer comprises alternating discrete sections of soft magnetic material and sections of non-magnetic material, wherein the alternating sections are located along the long axis.
In yet another embodiment, the device further comprises a plurality of moveable elements supported by the substrate.
In still another embodiment, the device further comprises a plurality of movea
Ruan Meichun
Shen Jun
Wheeler Charles
Arizona State University
Donovan Lincoln
Ingrassia Fisher & Lorenz P.C.
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