A Comb Capacitance MEMS Accelerometer Structure

Abstract

The invention discloses a comb-tooth capacitive micro-electromechanical accelerometer structure. The structure includes a comb group, a quality block, a flexible beam, a flexible beam support rod and a comb tooth support rod. The mass block is a "day"-shaped frame structure, the comb teeth group is a comb teeth group with variable gaps, and the single comb tooth that constitutes the comb teeth group is a pentagonal tooth with a gradually changing tooth width in the overlapping area. The comb groups are distributed across the inner and outer sides of the mass block frame to form a differential capacitor. The movable teeth of the comb group are connected to the mass block, and are then suspended on the lowest point of the structure through four flexible beams on the four corners of the mass block frame. The two ends of the flexible beam support rods on the outer two sides are connected with the fixed teeth of the comb group and the comb support rods. The pentagonal teeth can increase the number of tooth pairs while maintaining the tooth gap ratio, which is beneficial to improve the sensitivity of the accelerometer. The cross-distributed comb group can compensate for the capacitance difference caused by the uneven etching process and improve the symmetry of the capacitance; it can also compensate the influence of the differential capacitance by the change of the ambient temperature and improve the stability of the accelerometer scale coefficient.

Description

technical field [0001] The invention belongs to the technical field of microelectromechanical accelerometer structures, and relates to a comb-tooth capacitive microelectromechanical accelerometer structure. Background technique [0002] The comb capacitive micro-electromechanical accelerometer has the advantages of small size, low power consumption, good stability, and strong overload capability. It is often used for acceleration, vibration, and inclination testing, and is widely used in medical, industrial, and military fields. [0003] The structure of a conventional comb capacitive MEMS accelerometer usually consists of a mass block, 4 sets of variable-gap comb teeth, 4 flexible beams and corresponding anchor points. Four sets of comb teeth are symmetrically distributed up and down on both sides of the mass block to form a differential capacitor. The fixed teeth of the comb set are connected to the anchor point, and the movable teeth are connected to the mass block. Four ...

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Problems solved by technology

[0004] The comb teeth of the above-mentioned types of accelerometers usually use square long teeth. Considering that the force on the end of the comb is smaller than that on the root, the width of the end of the comb does not have to be the same as the root. The extra mass brought about by this will affect the indicators of the accelerometer. design

The comb groups of the above-mentioned types of accelerometers are usually distributed symmetrically up and down or left and right to form a differential capacitance, which is easily affected by the unevenness of the etching process during processing; in addition, when the temperature changes and the material expands and contracts, the gap between the comb teeth will change slightly. Changes, resulting in changes in the base capacitance, affecting the stability of the accelerometer scale coefficient

Finally, the anchor points of the above-mentioned types of accelerometers are usually large and far away, resulting in a structure that is easily affected by the anchoring material

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