Texas Instruments Corporation

Other

Eric P Reidemeister

Larry K Johnson

Keith W Kawate

Robert O Southworth

Steven Beringhause

Raymond E Mandeville

Andrew A Amatruda

William Silva

Michael D Gouin

Douglas B Strott

Douglas B Christensen

An acceleration sensor is shown having a substrate (16, 16', 16', 16'') on which a capacitor detect plate (24) and source plate mounting portion (28c) are disposed. An electrically conductive blade member (40, 44) having an attachment portion (40a, 44h), a source plate portion (40i, 44a) and integrally attached beams (40b, 40c; 44b) extending along opposite sides of the blade member is mounted on the substrate by welding the attachment portion to a mounting element (36, 36', 36', 36'') which is closely received in a bore (32, 32', 32', 32'') formed through the substrate at the source plate mounting portion. The mounting element or the bore is formed with a surface suitable for forming an interference fit and for making electrical engagement with a conductive layer received in the bore. The mounting element has one end (36b, 36b', 36b') which extends above the top surface (26, 26') an adjustable selected amount(s) to provide desired spacing between the source plate portion and the detect plate. A single mounting element of a pair of mounting elements can be used and may be in the form of a solid (36, 36', 36'') or a hollow (36') pin.

Method of making an acceleration sensor

Acceleration sensor apparatus and method for making same

An acceleration sensor (10, 10', 10') in which a metal blade member (24) having a source plate portion (24a), attachment portion (24p) and integral resilient beams (24b) extending between the source plate portion and the attachment portion is attached to a pin (22) received in turn in a bore (18a) of a substrate (18). The metal blade member (24) is mounted on the substrate (18) so that the source plate portion is a selected distance from a detect plate (18b) mounted on the substrate. The sensor is disposed in a cylindrical housing (12, 12', 12') which can be directly mounted to a circuit board (50) through terminal pins (18g, 18h, 18i) or can be provided with a threaded fastener (12'd). In one embodiment first and second sensor modules are received in a housing (42) to sense acceleration forces in two perpendicular directions. In another embodiment tab (30b) extending from a signal conditioning circuit (30) is placed between a connector body (20') and the sidewall (12b) of housing (12) with a detent (12c) formed in the sidewall (12b) to effect an electrical connection between circuit (30) and housing (12'). An O-ring gasket (13) is placed between the sidewall (12b) and the connector body (20') outboard of the detent to provide an environmental seal.

Compact capacitive acceleration sensor

An accelerometer unit has a capacitor detect plate and a source place connector preferably defined respectively inside and outside a groove in one surface of a ceramic substrate. A flat metal member has an attachment portion secured in electrically conductive relation to the connector, has a source plate portion spaced over the detect plate to form a capacitor, and has integral resilient beams extending from the attachment portion to support the source plate portion spaced from the detect plate to be movable relative to the detect plate in response to acceleration force to provide an electrical signal. Preferably glass rods between the attachment member portion and source place connector facilitate the spacing. An electrically insulating housing base has integral pins extending through openings in the accelerometer unit substrate and in a separate electrical circuit unit to mount the circuit unit in spaced, overlying relation to the accelerometer unit, and an electrically conductive adhesive extends through guide holes in a gasket between the accelerometer and circuit units to electrically connect the circuit to the detect plate and to the connector on the ceramic substrate.

Accelerometer

An accelerometer has a capacitor detect plate defined on an electrically insulating substrate adjacent a capacitor source plate connector and has circuit paths on the substrate connected to the detect plate and source plate connector. A resilient metal plate has an attachment portion secured to the source plate connector, has a capacitor source plate portion, has integral first beam elements extending away from the attachment portion and has a second beam element extending from the first beam elements back toward the attachment portion to dispose the capacitor source plate in spaced relation to the detect plate to form a capacitor having selected initial capacitance. The capacitor source plate member portion is movable relative to the detect plate to modify device capacitance in response to acceleration. Electronic components are mounted on the substrate connected to the circuit paths to provide an output signal corresponding to the acceleration. Preferably the device is cantilever mounted on a housing base with a part of the device substrate carrying the metal member extending over a housing recess to isolate that device end from thermal stresses in an accelerometer unit.

Capacitive accelerometer with cantilever mount

An accelerometer has a capacitor detect plate defined on an electrically insulating substrate adjacent a capacitor source plate connector and has circuit paths on the substrate connected to the detect plate and source plate connector. A resilient metal plate has an attachment portion secured to the source plate connector, has a capacitor source plate portion, has integral first beam elements extending away from the attachment portion and has a second beam element extending from the first beam elements back toward the attachment portion to dispose the capacitor source plate in spaced relation to the detect plate to form a capacitor having selected initial capacitance. The capacitor source plate member portion is movable relative to the detect plate to modify device capacitance in response to acceleration. Electronic components are mounted on the substrate connected to the circuit paths to provide an output signal corresponding to the acceleration. Preferably the device is mounted on a housing base with a part of the device substrate carrying the metal member extending over a housing recess to isolate that device end from thermal stresses in an accelerometer unit. Preferably the detect plate, source plate connector, resilient metal member, are provided on and soldered on a plurality of detachable sections of a ceramic insulating substrate in a batch process, and the substrate sections are then separated to form a plurality of accelerometer devices.

Capacitive accelerometer

A capacitive acceleration sensor using a common PWB as one of the plates of the capacitive transducer and the wiring connections thereto. An acceleration input moves a capacitor plate to produce a measurable change in capacitance. An electronic signal conditioner accurately converts the capacitance output to a voltage signal to provide an acceleration sensor featuring accurate DC performance. The transducer and electronics are disposed on a PWB making up a complete sensor package. In a first embodiment, the capacitor comprises a fixed electrode on the PWB and a movable acceleration responsive electrode secured to a support by a conductive resilient member, the support coupled to an electrically conductive region on the PWB spaced from the fixed electrode by a guard ring to minimize stray charge between the capacitor electrodes. In a second embodiment, the movable capacitor electrode is supported at its center by a pair of electrically conductive members, one coupled to an electrically conductive region on a substrate spaced from the movable electrode by a sealing spacer. The fixed capacitor electrode is disposed either on the same substrate or a separate substrate on the opposite side of the movable electrode spaced from the movable electrode by a sealing spacer and having the fixed capacitor electrode thereon. The movable capacitor electrode can be secured at its center or at an edge and can be produced by stamping and/or photoetching and provide a single element where plural elements were previously required.

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Arlington, MA, United States of America

Eric P Reidemeister