Accelerometric sensor with flectional vibratory beams
First Claim
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1. An accelerometric sensor, comprising:
- (a) a unitary generally parallelepiped plate-like member containing along its central longitudinal axis in a direction parallel with its sides a central plane (PM) and including at one end a fixed mass part (1);
(b) said member including at its other end a movable mass part (2), said member having a uniform thickness defining the thickness of said mass parts;
(c) two flectional vibrating beams (31,32) that extend longitudinally between said mass parts and each having ends integral with said mass parts, respectively; and
(d) two second beams (41,42) extending longitudinally between said mass parts and each having ends integral with said mass parts, respectively, said second beams having longitudinal central axes contained in said central plane;
(e) said vibrating beams being formed by chemical machining from said plate-like member with the longitudinal axes of said vibrating beams being offset relative to each other on opposite sides of said central plane and being contained in a plane P that is obliquely arranged relative to said central plane;
(f) said second beams having a flexural stiffness higher than the flexural stiffness of said vibrating beams.
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Abstract
The accelerometric sensor is of the type comprising a fixed mass, a mobile mass and two flectional vibrating beams each having ends that are linked to the masses. According to the invention, the masses and the beams consist of one single piece machined in a same plate of material of uniform thickness, e.g. in a piezoelectric material such as quartz. The single piece preferably comprises two second beams each having ends that are integral with the masses and placed on both sides of the vibratory beams. The flexural stiffness of the second beams is higher than that of the vibrating beams.
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11 Claims
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1. An accelerometric sensor, comprising:
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(a) a unitary generally parallelepiped plate-like member containing along its central longitudinal axis in a direction parallel with its sides a central plane (PM) and including at one end a fixed mass part (1); (b) said member including at its other end a movable mass part (2), said member having a uniform thickness defining the thickness of said mass parts; (c) two flectional vibrating beams (31,32) that extend longitudinally between said mass parts and each having ends integral with said mass parts, respectively; and (d) two second beams (41,42) extending longitudinally between said mass parts and each having ends integral with said mass parts, respectively, said second beams having longitudinal central axes contained in said central plane; (e) said vibrating beams being formed by chemical machining from said plate-like member with the longitudinal axes of said vibrating beams being offset relative to each other on opposite sides of said central plane and being contained in a plane P that is obliquely arranged relative to said central plane; (f) said second beams having a flexural stiffness higher than the flexural stiffness of said vibrating beams. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An accelerometric sensor, comprising:
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(a) a unitary generally parallelpiped plate-like member containing along its central longitudinal axis in a direction parallel with its sides a central plane (PM) and including at one end a fixed mass part adapted for attachment to a base; (b) a mobile mass part; (c) two flectional vibrating beams each having ends that are integral with said mass parts, respectively; (d) two second beams each having ends that are integral with said mass parts, said second beams having a flexural stiffness higher than the flexural stiffness of said vibrating beams; and (f) two pairs of electrode strips extending on coplanar sides of said vibrating beams and said fixed part, (g) said fixed and mobile mass parts and said vibrating and second beams constituting one single piece formed from a piezoelectric material plate having a uniform thickness, said vibratory beams being formed by chemical machining from said plate and being offset relative to each other on opposite sides of said central plane, the longitudinal axes of said vibratory beams being contained in a plane P that is obliquely arranged relative to said central plane.
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Specification