Passive tire pressure sensor and method
First Claim
1. A membrane actuated sensor device comprising:
- (a) a surface acoustical wave conductive body for transmitting a directional acoustical wave across at least a surface portion of the body;
(b) at least one conductive contact disposed at a pre-selected location on the surface portion of the body disposed to receive and reflect the acoustical wave back as a reflected signal;
(c) a flexible conductive membrane sealing against at least the surface portion of the body, the membrane being separated from the surface portion of the body by a cavity; and
(e) the conductive membrane deforming toward the surface portion to contact the conductive contact and modulate the signal reflected by the one conductive contact.
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Accused Products
Abstract
A surface acoustic wave device includes a micro-machined pressure transducer for monitoring tire pressure. The device is configured having a micro-machined cavity that is sealed with a flexible conductive membrane. When an external tire pressure equivalent to the cavity pressure is detected, the membrane makes contact with ridges on the backside of the surface acoustic wave device. The ridges are electrically connected to conductive fingers of the device. When the detected pressure is correct, selected fingers on the device will be grounded producing patterned acoustic reflections to an impulse RF signal. When the external tire pressure is less than the cavity reference pressure, a reduced reflected signal to the receiver results. The sensor may further be constructed so as to identify itself by a unique reflected identification pulse series.
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Citations
19 Claims
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1. A membrane actuated sensor device comprising:
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(a) a surface acoustical wave conductive body for transmitting a directional acoustical wave across at least a surface portion of the body; (b) at least one conductive contact disposed at a pre-selected location on the surface portion of the body disposed to receive and reflect the acoustical wave back as a reflected signal; (c) a flexible conductive membrane sealing against at least the surface portion of the body, the membrane being separated from the surface portion of the body by a cavity; and (e) the conductive membrane deforming toward the surface portion to contact the conductive contact and modulate the signal reflected by the one conductive contact. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A sensor device comprising:
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(a) a surface acoustical wave conductive body for transmitting a directional acoustical wave across at least a surface portion of the body; (b) at least one conductive contact disposed to receive and reflect the acoustical wave back as a reflected signal, the conductive contact switching between an electrically floating state and an electrically grounded state; (c) a flexible conductive membrane sealing against at least the surface portion of the body; and (d) the membrane deforming to electrically engage and ground the one conductive contact to modulate the signal reflected by the one conductive contact. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A method for measuring the magnitude of an external applied force on a sensor device comprising the steps:
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(e) transmitting an acoustical wave across at least a surface portion of a sensor device body; (f) positioning at least one conductive contact to intercept the acoustical wave and reflect a signal back; (g) positioning a flexible conductive membrane to seal against the surface portion; (h) deforming the membrane into electrically contacting engagement with the one conductive contact responsive to the application of an external force on the membrane of a predetermined magnitude; and (i) modulating the signal reflected by the one conductive contact responsive to electrical engagement between the one conductive contact and the deformed membrane. - View Dependent Claims (17, 18, 19)
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Specification