Micromachined accelerometer with electrostatic return
First Claim
1. An accelerometer sensor comprising a flat pendular structure made from one and the same crystalline wafer, said structure having in a same plane, a flat fixed part, at least two parallel blades flexible in the same plane and delimiting therebetween a space, each of said blades having a first end portion fixedly connected to said fixed part, and a second end portion, said structure further comprising a flat test body connected to the second end portions of said blades so as to be suspended from the flat fixed part and to be able to move in translation in the same plane along a sensitive axis under the effect of an acceleration with a position which varies in relation with said acceleration, said flat test body extending at least partially into said space, wherein said flat test body comprises at least a first edge which carries a first metallization having first and second opposite faces and said flat fixed part comprises at least a second and a third edge carrying respectively a second and a third metallizations, said second and third metallizations respectively facing said first and second opposite faces, so as to form two capacitors whose capacities vary depending on the position of said test body, said first metallization being brought to a first voltage V0, whereas the second and the third metallizations are respectively brought to a second and third voltages V1 and V2 which are capable of generating an electrostatic return force on the flat test body.
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Abstract
An accelerometer is provided using at least one sensor with flat pendular structure formed by micro-machining a fine monocrystal wafer and comprising a flat mobile mass suspended from the rest of the structure by means of two thin parallel strips situated on each side of the mass. The mass comprises at least one mobile capacitor plate disposed between two fixed capacitor plates provided on the fixed part of the structure. The mobile plate is brought to a voltage VO, whereas the fixed plates are respectively brought to voltages V1 and V2 which are capable of generating an electrostatic return force on the mobile mass.
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Citations
9 Claims
- 1. An accelerometer sensor comprising a flat pendular structure made from one and the same crystalline wafer, said structure having in a same plane, a flat fixed part, at least two parallel blades flexible in the same plane and delimiting therebetween a space, each of said blades having a first end portion fixedly connected to said fixed part, and a second end portion, said structure further comprising a flat test body connected to the second end portions of said blades so as to be suspended from the flat fixed part and to be able to move in translation in the same plane along a sensitive axis under the effect of an acceleration with a position which varies in relation with said acceleration, said flat test body extending at least partially into said space, wherein said flat test body comprises at least a first edge which carries a first metallization having first and second opposite faces and said flat fixed part comprises at least a second and a third edge carrying respectively a second and a third metallizations, said second and third metallizations respectively facing said first and second opposite faces, so as to form two capacitors whose capacities vary depending on the position of said test body, said first metallization being brought to a first voltage V0, whereas the second and the third metallizations are respectively brought to a second and third voltages V1 and V2 which are capable of generating an electrostatic return force on the flat test body.
Specification