# US 8,770,043 B2 · Comb-structured MEMS accelerometer > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,770,043 B2 - Document ID: US8770043B2 - Status: Granted - Kind: B2 - Application number: 12/996,270 - Filed: 2009-06-05 - Published: 2011-06-16 - Granted: 2014-07-08 - Earliest claimed: 2008-06-05 - Assignees: National University Corporation Shizuoka University - Applicants: Gen Hashiguchi - Inventors: Gen Hashiguchi - Web page: https://patentgrep.com/patent/US8770043B2 ## CPC - G01L 1/10: by measuring variations of frequency of stressed vibrating elements, e.g. of stressed strings (using resistance strain gauges G01L1/22) - G01P 15/097: by vibratory elements - H10D 48/50: Devices controlled by mechanical forces, e.g. pressure - G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G) - G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G}) - H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES ## Abstract An object of this invention is to detect an external force or acceleration with good sensitivity using a simple configuration. An external force detection sensor comprises a comb electrode including a fixed electrode having a plurality of fixed combtooth portions and a movable electrode having a plurality of movable combtooth portions inserted between the fixed combtooth portions; a power supply connected to the fixed electrode and the movable electrode in order to cause vibration of the movable electrode at a prescribed resonance frequency through an electrostatic force on the fixed electrode; and detection means for detecting an external force based on a change in electrical characteristics between the fixed electrode and the movable electrode when the movable electrode is caused to vibrate. With respect to the fixed combtooth portions that are adjacent to each other and the movable combtooth portion inserted therebetween, the spacing between one of the fixed combtooth portions and the movable combtooth portion is different from the spacing between another of the fixed combtooth portions and the movable combtooth portion. ## Claims ### Claim 1 A detection sensor, comprising: a comb electrode, including a fixed electrode having a plurality of fixed combtooth portions and a movable electrode having a plurality of movable combtooth portions inserted between the fixed combtooth portions; a power supply, connected to the fixed electrode and the movable electrode in order to cause vibration of the movable electrode at a prescribed resonance frequency through an electrostatic force on the fixed electrode; and a detection unit for detecting an external force or acceleration based on a change in electrical characteristics between the fixed electrode and the movable electrode when the movable electrode is caused to vibrate, wherein with respect to the fixed combtooth portions that are adjacent to each other and the movable combtooth portion inserted therebetween, the spacing between one of the fixed combtooth portions and the movable combtooth portion is different from the spacing between another of the fixed combtooth portions and the movable combtooth portion, and wherein the power supply changes a direction of vibration of the movable electrode by switching the prescribed frequency, between a first resonance frequency which causes vibration in an arrangement direction of the movable combtooth portions, and a second resonance frequency which causes vibration in an extension direction of the movable combtooth portions, wherein the movable electrode vibrates in the arrangement direction of the movable combtooth portions at the first resonance frequency, and vibrates in the extension direction of the movable combtooth portions at the second resonance frequency; and wherein the power supply generates a signal in which a DC bias signal is superposed on the signal at the prescribed resonance frequency. ### Claim 2 (depends on 1) The detection sensor according to claim 1, wherein the length of the fixed combtooth portions in a direction perpendicular to an extension direction and an arrangement direction of the fixed combtooth portions are different from the length of the movable combtooth portions in a direction perpendicular to an extension direction and an arrangement direction of the movable combtooth portions, and the power supply imparts electric power at a resonance frequency which causes vibration of the movable electrode in the direction perpendicular to the extension direction and the arrangement direction of the movable combtooth portions. ### Claim 3 (depends on 1) The detection sensor according to claim 1, wherein one of the first resonance frequency and the second resonance frequency is an integral multiple of the other. ### Claim 4 A detection sensor, comprising: a comb electrode, including a fixed electrode having a plurality of fixed combtooth portions and a movable electrode having a plurality of movable combtooth portions inserted between the fixed combtooth portions; a power supply, connected to the fixed electrode and the movable electrode in order to cause vibration of the movable electrode at resonance frequencies through an electrostatic force on the fixed electrode; and a detection unit for detecting an external force or acceleration based on a change in electrical characteristics between the fixed electrode and the movable electrode when the movable electrode is caused to vibrate, wherein with respect to the fixed combtooth portions that are adjacent to each other and the movable combtooth portion inserted therebetween, the spacing between one of the fixed combtooth portions and the movable combtooth portion is different from the spacing between another of the fixed combtooth portions and the movable combtooth portion, wherein the power supply generates a signal in which are superposed a first resonance frequency which causes the movable electrode to vibrate in an arrangement direction of the movable combtooth portions, and a second resonance frequency which causes the movable electrode to vibrate in an extension direction of the movable combtooth portions; and wherein a DC bias signal is superposed on said signal generated by said power supply. ### Claim 5 (depends on 4) The detection sensor according to claim 4, wherein the length of the fixed combtooth portions in a direction perpendicular to an extension direction and an arrangement direction of the fixed combtooth portions are different from the length of the movable combtooth portions in a direction perpendicular to an extension direction and an arrangement direction of the movable combtooth portions, and the power supply imparts electric power at a resonance frequency which causes vibration of the movable electrode in the direction perpendicular to the extension direction and the arrangement direction of the movable combtooth portions. ### Claim 6 (depends on 4) The detection sensor according to claim 4, wherein one of the first resonance frequency and the second resonance frequency is an integral multiple of the other.