Accelerometers and associated control circuits
First Claim
1. An accelerometer unit comprising:
- an electrically conductive plate having a center portion including an opening therethrough and an edge portion,first and second piezoelectric elements of substantially identical configuration mounted on opposite surfaces of the electrically conductive plate including openings concentric with the opening in the electrically conductive plate,a post having a longitudinal bore, the post being received through the openings in the piezoelectric elements and electrically conductive plate for supporting the center portion of the plate, the edge portion being free to flex in response to applied acceleration forces, an electrically insulative sleeve being disposed in said openings in the piezoelectric elements and electrically conductive plate and surrounding said post, andmeans connecting the first and second piezoelectric elements electrically in parallel for offsetting any electrical signals arising from pyroelectric effects of the piezoelectric elements.
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Accused Products
Abstract
An accelerometer unit characterized by first and second piezo-electric elements (5, 6) mounted upon opposed surfaces of an electrically conductive sheet, plate or the like (1), and in that the sheet, plate or the like is adapted to be centrally supportable by support (12) such that the first and second piezo-electric elements are subjectable to similar forces upon subjecting the piezo-electric elements to acceleration forces. The elements (5, 6) are connected electrically in parallel so that the effects of one piezo-electric element are caused to negate electrical output arising from pyroelectric effects of the other piezeo-electric element. A combined band pass filter and amplification circuit in which at least a part of the capacitance (37) of the initial high frequency pass filter of the circuit is provided by the capacitance of the piezo-electric elements.
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Citations
9 Claims
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1. An accelerometer unit comprising:
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an electrically conductive plate having a center portion including an opening therethrough and an edge portion, first and second piezoelectric elements of substantially identical configuration mounted on opposite surfaces of the electrically conductive plate including openings concentric with the opening in the electrically conductive plate, a post having a longitudinal bore, the post being received through the openings in the piezoelectric elements and electrically conductive plate for supporting the center portion of the plate, the edge portion being free to flex in response to applied acceleration forces, an electrically insulative sleeve being disposed in said openings in the piezoelectric elements and electrically conductive plate and surrounding said post, and means connecting the first and second piezoelectric elements electrically in parallel for offsetting any electrical signals arising from pyroelectric effects of the piezoelectric elements. - View Dependent Claims (2)
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3. An accelerometer unit comprising:
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an electrically conductive plate having a center portion including an opening therethrough and an edge portion, first and second piezoelectric elements of substantially identical configuration mounted on opposite surfaces of the electrically conductive plate including openings concentric with the opening in the electrically conductive plate, wherein each of the piezoelectric elements includes an outside surface facing away from the electrically conductive plate, a post having a longitudinal bore, the post being received through the openings in the piezoelectric elements and electrically conductive plate for supporting the center portion of the plate, the edge portion being free to flex in response to applied acceleration forces, and means connecting the first and second piezoelectric elements electrically in parallel for offsetting any electrical signals arising from pyroelectric effects of the piezoelectric elements, wherein the means for offsetting the electrical outputs arising from pyroelectric effects of the piezoelectric elements further includes means for electrically connecting the outside surfaces of the piezoelectric elements to said post.
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4. An accelerometer unit comprising:
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an electrically conductive plate having a center portion and an edge portion, the center portion including an opening therethrough, first and second piezoelectric elements mounted on opposite surfaces of the electrically conductive plate, the first and second piezoelectric elements including openings concentric with the opening in the electrically conductive plate, a post having a longitudinal bore, the post being received through the openings in the piezoelectric elements and electrically conductive plate for supporting the center portion of the plate, the edge portion being free to flex in response to applied acceleration forces, an electrically insulative sleeve disposed in said openings in the piezoelectric elements and electrically conductive plate and surrounding said post, connecting means connecting the first and second piezoelectric elements electrically in parallel to a pair of electrodes, the piezoelectric elements exhibiting an inherent capacitance of known value, the piezoelectric elements generating an electrical signal across the electrodes which is proportional to the acceleration experienced by the piezoelectric elements, and an amplification circuit for amplifying the electrical signal generated by the piezoelectric elements, the amplification circuit including at an input thereof a resistor coupled to a first of the electrodes to define with said inherent capacitance a pass filter for restricting the frequency of the signal generated by the piezoelectric elements which the amplification circuit will amplify. - View Dependent Claims (5, 6, 7, 8, 9)
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Specification