# US 2019/0377136 A1 · Capacitive Position Sensing for Capacitive Drive MEMS Devices > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0377136 A1 - Document ID: US20190377136A1 - Status: Published application - Kind: A1 - Application number: 16/221,523 - Filed: 2018-12-16 - Published: 2019-12-12 - Earliest claimed: 2018-06-06 - Assignees: Apple Inc. - Applicants: Apple Inc. - Inventors: Sebastian Fluegel; Andrew J. Sutton; Bryce T. Bradford; Yuval Gerson - Web page: https://patentgrep.com/patent/US20190377136A1 ## CPC - G02B 6/357: {Electrostatic force (electrostatic forces controlling reflecting elements in general G02B26/0841)} - G02B 6/3584: {constructional details of an associated actuator having a MEMS construction, i.e. constructed using semiconductor technology such as etching (MEMS per se B81B, B81C)} - G02B 26/0841: {the reflecting element being moved or deformed by electrostatic means} - G01P 15/125: by capacitive pick-up - G02B 6/359: {of the position of the moving element itself during switching, i.e. without monitoring the switched beams} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - 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}) ## Abstract An apparatus for driving and position sensing in a comb-drive actuator includes a generator, a driver circuit, sensing circuitry, and signal processing circuitry. The generator is configured to apply a sensing-voltage to a first electrode of the comb-drive actuator. The driver circuit is configured to apply a drive-voltage to a second electrode of the comb-drive actuator, having an opposite polarity relative to the first electrode. The sensing circuitry is configured to measure at the second electrode a sensed-waveform resulting from the sensing-voltage applied to the first electrode. The signal processing circuitry is configured to estimate a position of the first electrode relative to the second electrode based on the sensed-waveform. ## Claims ### Claim 1 An apparatus for driving and position sensing in a comb-drive actuator, the apparatus comprising: a generator, configured to apply a sensing-voltage to a first electrode of the comb-drive actuator; a driver circuit, configured to apply a drive-voltage to a second electrode of the comb-drive actuator, having an opposite polarity relative to the first electrode; sensing circuitry, which is configured to measure at the second electrode a sensed-waveform resulting from the sensing-voltage applied to the first electrode; and signal processing circuitry, which is configured to estimate a position of the first electrode relative to the second electrode based on the sensed-waveform. ### Claim 2 (depends on 1) The apparatus according to claim 1, wherein the sensed-waveform falls on a resistor connected in series to the second electrode. ### Claim 3 (depends on 1) The apparatus according to claim 1, wherein the sensed-waveform is measured by a circuit having an adaptive reference ground. ### Claim 4 (depends on 1) The apparatus according to claim 1, wherein the sensing-voltage comprises a sine waveform. ### Claim 5 (depends on 1) The apparatus according to claim 1, wherein: the generator is configured to apply the sensing-voltage to a common first electrode of two or more comb-drive actuators; the driver circuit comprises two or more driver circuits configured to apply respective drive-voltages to two or more respective second electrodes of the two or more comb-drive actuators; the sensing circuitry is configured to measure at the second electrodes respective sensed-waveforms resulting from the sensing-voltage applied to the common first electrode; and the signal processing circuitry is configured to estimate positions of the first electrodes relative to the respective second electrodes based on the respectively sensed-waveforms. ### Claim 6 A method for driving and position sensing in a comb-drive actuator, the method comprising: applying a sensing-voltage to a first electrode of the comb-drive actuator; applying a drive-voltage to a second electrode of the comb-drive actuator, having an opposite polarity relative to the first electrode; measuring at the second electrode a sensed-waveform resulting from the sensing-voltage applied to the first electrode; and estimating a position of the first electrode relative to the second electrode based on the sensed-waveform. ### Claim 7 (depends on 6) The method according to claim 6, wherein measuring the sensed-waveform comprises measuring the sensed-waveform that falls on a resistor connected in series to the second electrode. ### Claim 8 (depends on 6) The method according to claim 6, wherein measuring the sensed-waveform comprises measuring the sensed-waveform using a circuit having an adaptive reference ground. ### Claim 9 (depends on 6) The method according to claim 6, wherein applying the sensing-voltage comprises applying a sine waveform. ### Claim 10 (depends on 6) The method according to claim 6, wherein: applying the sensing-voltage comprises applying the sensing-voltage to a common first electrode of two or more comb-drive actuators; applying the drive-voltage comprises applying respective drive-voltages to two or more second electrodes of two or more respective comb-drive actuators; measuring at the two or more second electrodes respective sensed-waveforms resulting from the sensing-voltage applied to the common first electrode; and estimating positions of the first electrodes relative to the respective second electrodes based on the sensed-waveforms.