Electrical transmission or interconnection systems – Switching systems
Reexamination Certificate
1999-10-06
2001-09-18
Ballato, Josie (Department: 2836)
Electrical transmission or interconnection systems
Switching systems
C307S121000, C307S010100, C073S514110, C073S514240
Reexamination Certificate
active
06291908
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a switch apparatus and, more particularly, to a micro-miniature switch apparatus that may be manufactured using a semiconductor fabrication technique.
BACKGROUND OF THE INVENTION
High speed switch devices are used in various technologies, including, for example, automotive safety systems and microwave relay systems. In each of these systems, switch devices must operate reliably and at high frequencies.
In a vehicle safety system, for example, inertia-operated mechanical switches often are used to sense the onset of a vehicle crash event and trigger the actuation of an occupant protection device (e.g., an air bag or a seat belt pretensioner). More recently, vehicles are being equipped with one or more electronic acceleration sensors working in cooperation with a microprocessor and sophisticated software. The sensors provide electronic signals proportional to sensed vehicle acceleration. The microprocessor assesses the changes in the vehicle's acceleration to determine whether the signal indicates that a vehicle crash event is in progress that requires actuation of the occupant protection system.
Safing switches often are used in combination with acceleration sensors to provide a redundant level of detection for a vehicle crash event. The safing switch usually is designed and calibrated to close at a relatively early stage in a crash event. The occupant protection device (e.g., an air bag or seat belt pretensioner) is only actuated when the safing switch is closed and the microprocessor determines that the severity of the crash is sufficient to warrant such actuation.
Safing switches may be manufactured by processes generally similar to those used to assemble other small mechanical devices. Efforts are being made, however, to develop smaller switches that could be manufactured using techniques like those used to manufacture semiconductor components and/or micro-machined silicon elements. Patents describing such micro-machined switch devices include U.S. Pat. Nos. 5,331,853 and 5,591,910.
U.S. Pat. No. 5,331,853 discloses an acceleration sensor micro-machined from a silicon substrate. The sensor includes pair of accelerometers, each having a force sensing axis. Each accelerometer includes a mass supported by micro-machined flexures connected to a support frame so as to permit movement of the mass relative to the substrate. Each accelerometer measures movement of. the associated mass so as to provide an output signal indicative of the sensed acceleration along its force-sensing axis.
U.S. Pat. No. 5,591,910 discloses a micro-machined acceleration sensor formed of an inertial mass supported above a substrate by flexure hinges. The inertial mass moves relative to the substrate when subjected to an acceleration perpendicular to the plane of the substrate. Movement of the mass results in a change in a capacitance value of the sensor. The changing capacitance value is indicative of acceleration.
Other examples of micro-machined switch devices and accelerometers are disclosed in U.S. Pat. Nos. 4,736,629; 4,882,933; 5,541,437; 5,635,739; and 5,804,783.
SUMMARY OF THE INVENTION
In accordance with one aspect, the present invention provides a micro-miniature switch apparatus that includes a substrate which has a surface. First and second channels extend from the surface into the substrate. The first and second channels are spaced apart from each other, with a channel axis extending longitudinally through the channels. A body that is movable relative to the substrate includes two arms. Each of the arms extends into one of the first and second channels to support the body for movement relative to the substrate between first and second electrical conditions of the switch apparatus.
In accordance with another aspect, the present invention provides a micro-miniature acceleration switch apparatus that includes a substrate which has a surface. A pair of channels extend from the surface into the substrate. Each of the channels has a channel axis, and each channel axis is parallel with the other channel axis. The apparatus also includes a body that is movable relative to the substrate. The body has two substantially coaxial arms. Each arm extends from a central part of the body into a bearing relationship with one of the first and second channels to support the body for movement relative to the substrate from a first switch position to a second switch position when the switch apparatus is accelerated in a direction substantially orthogonal to the surface of the substrate.
In accordance with yet another aspect, the present invention provides a micro-miniature acceleration switch apparatus that includes a substrate having a surface. Two fulcrum supports are formed at the surface of the substrate, with each of the fulcrum supports being spaced apart from the other fulcrum support. A body that is movable relative to the substrate includes a plate positioned near the surface of the substrate at a location between the fulcrum supports. The body also includes two substantially coaxial arms that extend from the plate into a bearing relationship with an associated one of the fulcrum supports to permit rocking movement of the body relative to the substrate. The body is movable relative to the substrate between first and second switch positions in response to acceleration of the switch apparatus in a direction orthogonal to the surface of the substrate.
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Berenz John Joseph
DePace Ronald A.
Rochin Luis M.
Roth Thomas J.
Tran Dean
Ballato Josie
Deberadinis Robert
Tarolli, Sundheim, Covell Tummino & Szabo L.L.P.
TRW Inc.
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