Acceleration sensor
First Claim
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1. An acceleration sensor comprising:
- a base;
a deformable beam comprising a first portion rigidly secured to the base and a second portion movable, by deformation of the beam in response to an acceleration force exerted thereon, from a predetermined initial position relative to the first portion to a second position displaced from the initial position by an amount proportional to the exerted acceleration force, and returnable to the initial position upon cessation of the acceleration force;
a permanent magnet attached to the second portion of the deformable beam for common movement therewith;
first and second magnetic sensors respectively comprising;
first and second zig-zag patterns of magnetic think film lying substantially in a common plane, each film pattern comprising a first plurality of spaced, parallel segments extending in a first direction and a second plurality of spaced, parallel segments extending in a second direction transverse to the first direction and respectively, integrally interconnecting the adjacent first segments at the opposite ends thereof in an alternating sequence in accordance with the zig-zag pattern;
the respective first segments of the first and second zig-zag patterns being in interdigitized and parallel, spaced relationship and with the respective, second segments thereof being in spaced and parallel, aligned relationship;
the first and second zig-zag patterns of magnetic thin films having respective, first ends defining corresponding input terminal pads and respective, second ends connected together to form a common output terminal pad;
first and second patterns of parallel, spaced line segments conductive material having a higher conductivity than that of the magnetic thin film, formed on the respective first and second zig-zag patterns of magnetic thin film, the first conductive pattern line segments being angularly inclined, relatively to the first plurality of parallel segments of the first zig-zag pattern, in a first sense, and the second conductive line segments being angularly inclined, relatively to the first plurality of parallel segments of the second, zig-zag pattern in a second, opposite sense, the first and second conductive material line segment patterns producing respective, first and second net bias current flow paths in the corresponding first and second magnetic thin film patterns which are angularly inclined with respect to each other;
the first and second magnetic sensors being fixedly mounted on the base at predetermined positions substantially symmetrically spaced from the magnet relative to the initial position of the deformable beam and with the common plane thereof parallel to the magnetic flux of the permanent magnet, the magnetic sensors producing respective outputs which are proportional to the extent of movement of the permanent magnet and correspondingly of the second portion of the deformable beam from the predetermined initial position thereof and thus to the acceleration force exerted thereon; and
an electrical circuit receiving the respective outputs of the magnetic sensors the producing an output indication of the acceleration force.
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Abstract
An acceleration sensor including a cantilever beam having a free end to which a permanent magnet is attached. A pair of magnetic sensors, each comprising a barber-pole type magnetoresistive sensing element, is arranged in symmetrically spaced and opposed relationship and in a common plane extending parallel to the magnetic flux of the permanent magnet with respect to respective, opposite sides of the magnet. The cantilever is bent and the magnet is moved accordingly in response to an acceleration force, which is detected as outputs from the magnetoresistive sensing elements.
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Citations
13 Claims
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1. An acceleration sensor comprising:
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a base; a deformable beam comprising a first portion rigidly secured to the base and a second portion movable, by deformation of the beam in response to an acceleration force exerted thereon, from a predetermined initial position relative to the first portion to a second position displaced from the initial position by an amount proportional to the exerted acceleration force, and returnable to the initial position upon cessation of the acceleration force; a permanent magnet attached to the second portion of the deformable beam for common movement therewith; first and second magnetic sensors respectively comprising; first and second zig-zag patterns of magnetic think film lying substantially in a common plane, each film pattern comprising a first plurality of spaced, parallel segments extending in a first direction and a second plurality of spaced, parallel segments extending in a second direction transverse to the first direction and respectively, integrally interconnecting the adjacent first segments at the opposite ends thereof in an alternating sequence in accordance with the zig-zag pattern; the respective first segments of the first and second zig-zag patterns being in interdigitized and parallel, spaced relationship and with the respective, second segments thereof being in spaced and parallel, aligned relationship; the first and second zig-zag patterns of magnetic thin films having respective, first ends defining corresponding input terminal pads and respective, second ends connected together to form a common output terminal pad; first and second patterns of parallel, spaced line segments conductive material having a higher conductivity than that of the magnetic thin film, formed on the respective first and second zig-zag patterns of magnetic thin film, the first conductive pattern line segments being angularly inclined, relatively to the first plurality of parallel segments of the first zig-zag pattern, in a first sense, and the second conductive line segments being angularly inclined, relatively to the first plurality of parallel segments of the second, zig-zag pattern in a second, opposite sense, the first and second conductive material line segment patterns producing respective, first and second net bias current flow paths in the corresponding first and second magnetic thin film patterns which are angularly inclined with respect to each other; the first and second magnetic sensors being fixedly mounted on the base at predetermined positions substantially symmetrically spaced from the magnet relative to the initial position of the deformable beam and with the common plane thereof parallel to the magnetic flux of the permanent magnet, the magnetic sensors producing respective outputs which are proportional to the extent of movement of the permanent magnet and correspondingly of the second portion of the deformable beam from the predetermined initial position thereof and thus to the acceleration force exerted thereon; and an electrical circuit receiving the respective outputs of the magnetic sensors the producing an output indication of the acceleration force. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An acceleration sensor comprising:
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a base; a deformable beam member having a first portion rigidly secured to said base and a second portion movable from a predetermined, initial position relative to the base in response to and by an extent proportional to an acceleration force exerted thereon and returnable to said initial position when an acceleration is not exerted thereon; a permanent magnet affixed to said deformable beam at said second portion; said deformable beam and said permanent magnet being formed integrally and of a semirigid magnetic material; a pair of magnetic sensors, each comprising a magnetoresistive sensing element, fixedly mounted on said base opposite to said magnet and arranged substantially symmetrically with respect to said magnet in the absence of any acceleration force being exerted thereon and thus at the initial position thereof; and an electrical circuit for detecting the acceleration according to outputs from said magnetic sensors. - View Dependent Claims (13)
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Specification