# US 2018/0136271 A1 · Capacitive sensor with self-test feature > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0136271 A1 - Document ID: US20180136271A1 - Status: Published application - Kind: A1 - Application number: 15/810,696 - Filed: 2017-11-13 - Published: 2018-05-17 - Earliest claimed: 2016-11-14 - Assignees: Touchsensor Technologies, LLC - Applicants: Touchsensor Technologies, LLC - Inventors: Randall Philipson - Web page: https://patentgrep.com/patent/US20180136271A1 ## CPC - G01R 31/2829: {Testing of circuits in sensor or actuator systems (testing of apparatus for measuring electric or magnetic variables G01R35/00; testing of indicating or recording apparatus G01D; in airbag systems B60R21/0173; checking gas analysers G01N33/007; monitoring or fail-safe circuits for electromagnets H01F7/1844)} - G01R 35/007: {Standards or reference devices, e.g. voltage or resistance standards, "golden references"} - G06F 3/0445: {using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer} - H03K 17/962: {Capacitive touch switches} - H03K 2017/9613: {using two electrodes per touch switch} - H03K 2217/960705: Safety of capacitive touch and proximity switches, e.g. increasing reliability, fail-safe - H03K 2217/960745: Capacitive differential; e.g. comparison with reference capacitance - H03K 2217/960765: Details of shielding arrangements - H03K 2217/96077: comprising an electrode which is floating - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M) ## Abstract A capacitive sensor includes sensor electrode structure and a controller operating the sensor. The sensor also includes test drive electrode structure or a reference capacitor, the controller operating the test drive electrode structure or the reference capacitor to test operability of the sensor. ## Claims ### Claim 1 A capacitive sensor comprising: a first dielectric substrate having a first side and a second side; a sensor electrode structure having a first sensing electrode disposed on the first side of the dielectric substrate; and a controller coupled to the first sensing electrode, the controller configured to: selectively energize the first sensing electrode, selectively detect capacitance at the first sensing electrode, and deem the sensor to be actuated or not actuated based on the capacitance detected at the first sensing electrode; selectively simulate actuation of the sensor while the sensor is not actuated; and selectively simulate deactivation of the sensor while the sensor is actuated or while the controller is simulating actuation of the sensor. ### Claim 2 (depends on 1) The sensor of claim 1 further comprising: a test drive electrode structure disposed on the second side of the first dielectric substrate, the test drive electrode structure comprising a first test drive electrode and a second test drive electrode; the capacitive sensor electrode structure further comprising a second sensing electrode disposed on the first side of the first dielectric substrate, the first sensing electrode at least partially overlying and in registration with the first test drive electrode, and the second sensing electrode at least partially overlying and in registration with the second test drive electrode; and the controller further coupled to the second sensing electrode and to the first and second test drive electrodes; the controller further configured to: selectively energize one or both of the first sensor electrode and the second sensor electrode, selectively detect capacitance at one or both of the first sensor electrode and the second sensor electrode, and deem the sensor to be actuated or not actuated based on the capacitance detected at the first sensing electrode; selectively simulate actuation of the sensor while the sensor is not actuated by coupling the first test drive electrode to a ground potential and holding the second test drive electrode at a floating potential; and selectively simulate deactivation of the sensor while the sensor is actuated or while the controller is simulating actuation of the sensor by coupling both the first test drive electrode and the second test drive electrode to the ground potential. ### Claim 3 (depends on 2) The sensor of claim 2 wherein the controller is configured to deem the sensor to actuate properly if the controller deems the sensor to actuate while not actuated in response to the grounding of the first test drive electrode. ### Claim 4 (depends on 2) The sensor of claim 2 wherein the controller is configured to deem the sensor to not actuate properly if the controller deems the sensor to not actuate while not actuated in response to the grounding of the first test drive electrode. ### Claim 5 (depends on 2) The sensor of claim 2 wherein the controller is configured to deem the sensor to deactuate properly if the controller deems the sensor to deactuate when actuated in response to the grounding of the first test drive electrode and the second test drive electrode. ### Claim 6 (depends on 2) The sensor of claim 2 wherein the controller is configured to deem the sensor to not deactuate properly if the controller deems the sensor to not deactuate while actuated in response to the grounding of the first test drive electrode and the second test drive electrode. ### Claim 7 (depends on 2) The sensor of claim 2 wherein the controller is configured to deem the sensor to operate properly if the controller deems the sensor to actuate while not actuated in response to the grounding of the first test drive electrode, and if the controller deems the sensor to deactuate while actuated in response to the grounding of the first test drive electrode and the second test drive electrode. ### Claim 8 (depends on 2) The sensor of claim 2 wherein the controller is configured to deem the sensor to not operate properly if the controller deems the sensor to actuate while not actuated in response to the grounding of the first test drive electrode, and if the controller deems the sensor to deactuate while actuated in response to the grounding of the first test drive electrode and the second test drive electrode. ### Claim 9 (depends on 1) The sensor of claim 1 further comprising: a reference capacitor proximate the first sensing electrode, the reference capacitor having a first plate and a second plate; and a switch operable to selectively couple the second plate of the reference capacitor to ground, to a floating potential, or to the controller; the controller further coupled to the capacitive sensor and to the first plate of the reference capacitor, the controller further configured to: selectively energize the first sensor electrode, selectively detect capacitance at the first sensor electrode, and deem the sensor to be actuated or not actuated based on the capacitance detected at the first sensing electrode when the switch is configured to couple the second plate of the capacitor to the floating potential; selectively energize the first plate of the reference capacitor and selectively detect the capacitance at the first plate of the reference capacitor; selectively energize the second plate of the reference capacitor as a driven shield; deem the sensor to actuate properly when, with the sensor not actuated and with the controller coupled to the second plate of the reference capacitor and energizing the second plate of the reference capacitor as a driven shield, the controller deems the capacitance of the reference capacitor to differ by a first predetermined value from the capacitance of the reference capacitor when the switch is configured to couple the second plate of the reference capacitor to the floating potential; and deem the sensor to deactuate properly when, with the sensor actuated the sensor actuated and with the switch configured to couple the second plate of the reference capacitor to ground, the controller deems the capacitance of the reference capacitor to differ by a second predetermined value from the capacitance of the reference capacitor when the switch is configured to couple the second plate of the reference capacitor to the floating potential. ### Claim 10 (depends on 9) The apparatus of claim 9 wherein the first predetermined value is lower than the capacitance of the reference capacitor when the switch is configured to couple the second plate of the reference capacitor to the floating potential and the second predetermined value is greater than the capacitance of the reference capacitor when the switch is configured to couple the second plate of the reference capacitor to the floating potential. ### Claim 11 (depends on 1) The sensor of claim 1 further comprising: a test drive electrode disposed on the second side of the first dielectric substrate, the test drive electrode at least partially overlying and in registration with the first sensing electrode; and the controller further coupled to the test drive electrode; the controller further configured to: selectively energize the first sensing electrode, selectively detect capacitance at the first sensing electrode, and deem the sensor to be actuated or not actuated based on the capacitance detected at the first sensing electrode when the test drive electrode is at a floating potential, selectively simulate actuation of the sensor while the sensor is not actuated by coupling the test drive electrode to a ground potential; and selectively simulate deactivation of the sensor while the sensor is actuated or while the controller is simulating actuation of the sensor by energizing the test drive electrode as a driven shield. ### Claim 12 A capacitive sensor comprising: a first dielectric substrate having a first side and a second side; a sensor electrode structure having a sense electrode disposed on the first side of the dielectric substrate and a drive electrode on the second side of the dielectric substrate, the drive electrode at least partially overlying and in registration with the sense electrode; a reference capacitor proximate the sense electrode, the reference capacitor having a first plate and a second plate; a first switch operable to selectively couple the second plate of the reference capacitor to ground or to a floating potential; a second switch operable to selectively couple the sense electrode to ground; and a controller coupled to the sense electrode and the drive electrode, the controller configured to: with the first switch configured to couple the second plate of the reference capacitor to the floating potential, and with the second switch not configured to couple the sense electrode to ground, operate the capacitive sensor by selectively energizing the drive electrode, selectively detect capacitance at the sense electrode, and deem the sensor to be actuated or not actuated based on the capacitance detected at the sense electrode; operate the reference capacitor by selectively energizing the first plate of the reference capacitor and selectively detecting the capacitance at the first plate of the reference capacitor; deem the sensor to actuate properly when, with the sensor not actuated, with the first switch configured to couple the second plate of the reference capacitor to the floating potential and the second switch configured to couple the sense electrode to ground, the controller deems the capacitance of the reference capacitor to differ by a first predetermined value from the capacitance of the reference capacitor when the switch is configured to couple the second plate of the reference capacitor to the floating potential; and deem the sensor to deactuate properly when, with the sensor actuated, the first switch configured to couple the second plate of the reference capacitor to ground, and the second switch configured to couple the sense electrode to ground, the controller deems the capacitance of the reference capacitor to differ by a second predetermined value from the capacitance of the reference capacitor when the switch is configured to couple the second plate of the reference capacitor to the floating potential.