# US 10,501,107 B2 · Method and device for detecting steering wheel contact > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,501,107 B2 - Document ID: US10501107B2 - Status: Granted - Kind: B2 - Application number: 15/522,017 - Filed: 2015-11-09 - Published: 2017-11-23 - Granted: 2019-12-10 - Earliest claimed: 2014-11-07 - Assignees: TRW Automotive Safety Systems GmbH - Applicants: TRW Automotive Safety Systems GmbH - Inventors: Hans-Jürgen Bossler; Martin Kreuzer; Guido Hirzmann; Alexander Lammers; Helga Heist - Web page: https://patentgrep.com/patent/US10501107B2 ## CPC - B62D 1/046: {Adaptations on rotatable parts of the steering wheel for accommodation of switches} - B62D 1/065: {Steering wheels with heating and ventilating means (heating and ventilation of steering wheel when connected to vehicle HVAC B60H1/00292)} - G01D 5/2417: {by varying separation} - H03K 17/955: using a capacitive detector - H03K 17/962: {Capacitive touch switches} - H03K 2217/960725: Charge-transfer - B62D: MOTOR VEHICLES; TRAILERS (steering, or guiding on a desired track, of agricultural machines or implements A01B69/00; wheels, castors, axles, increasing wheel adhesion B60B; vehicle tyres, tyre inflation or tyre changing B60C; connections between vehicles of a train or the like B60D; vehicles for use on rail and road, amphibious or convertible vehicles B60F; suspension arrangements B60G; heating, cooling, ventilating or other air treating devices B60H; windows, windscreens, non-fixed roofs, doors or similar devices, protective coverings for vehicles not in use B60J; propulsion plant arrangements, auxiliary drives, transmissions, controls, instrumentation or dashboards B60K; electric equipment or propulsion of electrically-propelled vehicles B60L; power supply for electrically-propelled vehicles B60M; passenger accommodation not otherwise provided for B60N; adaptations for load transportation or to carry special loads or objects B60P; arrangement of signalling or lighting devices, the mounting or supporting thereof or circuits therefor, for vehicles in general B60Q; vehicles, vehicle fittings or vehicle parts not otherwise provided for B60R; servicing, cleaning, repairing, supporting, lifting, or manoeuvring, not otherwise provided for, B60S; brake arrangements, brake control systems or parts thereof B60T; air-cushion vehicles B60V; motor-cycles, accessories therefor B62J, B62K; testing of vehicles G01M) - G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR - 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 device for detecting steering wheel contact comprises at least a first electrode (12) which is provided in a steering wheel (10) and which forms, together with a human body acting as a second electrode and a dielectric situated therebetween, at least one sensor capacitor (26). The device also comprises an evaluation circuit (24) having a reference capacitor (30) of known capacitance which can be connected parallel to the sensor capacitor (26), a direct current voltage source (34) which can be connected to the reference capacitor (30), and a measuring device for measuring the voltage at the reference capacitor (30). A method for detecting steering wheel contact using such a device comprises the following successive steps: charging the reference capacitor (30) by applying a known reference voltage, or charging the reference capacitor (30) and subsequently measuring a first voltage at the reference capacitor (30); connecting, in parallel, the sensor capacitor (26) to the reference capacitor (30) so that a portion of the charge of the reference capacitor (30) is transmitted to the sensor capacitor (26); measuring a second voltage at the reference capacitor (26); end determining the capacitance of the sensor capacitor (26) from the known capacitance of the reference capacitor (30), the reference voltage or the first voltage and the second voltage. ## Claims ### Claim 1 A device for detecting steering wheel contact comprising: at least one first electrode (12) which is provided in a steering wheel (10) and which forms, together with a human body acting as a second electrode and a dielectric situated therebetween, at least one sensor capacitor (26), and an evaluation circuit (24) having a reference capacitor (30) of known capacitance which is selectably connected in parallel to the sensor capacitor (26) through a first switch (32), and a direct current voltage source (34) which is selectably connected to the reference capacitor (30) through a second switch (28), the direct current voltage source (34) being connected to the reference capacitor (30) through the second switch (28) when the second switch (28) is closed and the first switch (32) is open, the reference capacitor (30) being separated from the direct current voltage source (34) and connected in parallel to the at least one sensor capacitor (26) through the first switch (32) when the second switch (28) is open and the first switch (32) is closed, wherein voltage at the reference capacitor (30) is measured to detect steering wheel contact. ### Claim 2 (depends on 1) The device according to claim 1, wherein the evaluation circuit is arranged at least partially on a chip. ### Claim 3 (depends on 1) The device according to claim 1, wherein a metallic armature (16) of the steering wheel (10) or an electric conductor arranged between the steering wheel armature (16) and the first electrode (12) is placed on a constant potential or ground. ### Claim 4 (depends on 1) The device according to claim 1, wherein the evaluation circuit is arranged so that a metallic armature (16) of the steering wheel (10) or an electric conductor arranged between the steering wheel armature (16) and the first electrode (12) is charged to a predetermined potential when the sensor capacitor (26) and the reference capacitor (30) are connected in parallel. ### Claim 5 (depends on 1) The device according to claim 1, wherein plural first electrodes (12) arranged to be spread over the steering wheel rim (14) are provided. ### Claim 6 (depends on 1) The device according to claim 1, wherein the first electrode (12) is formed by an electric conductor arranged in a steering wheel rim (14) of the steering wheel (10). ### Claim 7 (depends on 6) The device according to claim 6, wherein the electric conductor includes one or more wires (22). ### Claim 8 (depends on 6) The device according to claim 6, wherein the electric conductor includes one or more conductive tapes or bundles of plural strands. ### Claim 9 (depends on 6) The device according to claim 6, wherein the electric conductor includes an electrically conductive lacquer or an electrically conductive paste. ### Claim 10 (depends on 6) The device according to claim 6, wherein the electric conductor includes a metal plate or film. ### Claim 11 (depends on 6) The device according to claim 6, wherein the electric conductor is arranged within a foam-coating (18) which surrounds a steering wheel armature (16). ### Claim 12 (depends on 6) The device according to claim 6, wherein the electric conductor is applied to foam-coating (18) which surrounds a steering wheel armature (16). ### Claim 13 (depends on 6) The device according to claim 6, wherein the electric conductor is arranged directly beneath an outer wrapping (20) of the steering wheel rim (20). ### Claim 14 (depends on 6) The device according to claim 6, wherein the electric conductor extends substantially along the toroidal peripheral direction of the steering wheel rim (14). ### Claim 15 (depends on 6) The device according to claim 6, wherein the electric conductor extends substantially along the poloidal peripheral direction of the steering wheel rim (14). ### Claim 16 (depends on 6) The device according to claim 6, wherein the electric conductor is part of a metallic fabric or a metallic knit fabric. ### Claim 17 (depends on 6) The device according to claim 6, wherein the electric conductor is formed of a semiconductor material. ### Claim 18 (depends on 6) The device according to claim 6, wherein the electric conductor is applied to a carrier, especially to a textile, a mat or a film. ### Claim 19 (depends on 18) The device according to claim 18, wherein the electric conductor is fastened to one or both sides of the carrier by pulling through or stitching. ### Claim 20 (depends on 1) A method for detecting steering wheel contact using such device according to claim 1, comprising the following successive steps of: charging the reference capacitor (30) by applying a known reference voltage or charging the reference capacitor (30) and subsequently measuring a first voltage at the reference capacitor (30); connecting, in parallel, the sensor capacitor (26) to the reference capacitor (30) so that a portion of the charge of the reference capacitor (30) is transmitted to the sensor capacitor (26); measuring a second voltage at the reference capacitor (30); and determining the capacitance of the sensor capacitor (26) from the known capacitance of the reference capacitor (30), the reference voltage or the first voltage and the second voltage. ### Claim 21 (depends on 20) The method according to claim 20, wherein when the sensor capacitor (26) and the reference capacitor (30) are connected in parallel, an electric conductor serving as a shielding within the steering wheel is charged to a predetermined potential. ### Claim 22 (depends on 20) The method according to claim 20, wherein for sensing steering wheel contact at least one threshold value for the capacitance of the sensor capacitor (26) which is preferably based on empirically established empirical values is resorted to. ### Claim 23 (depends on 20) The method according to claim 20, wherein plural sensor capacitors (26) are monitored by means of the evaluation circuit. ### Claim 24 (depends on 20) The method according to claim 20, wherein the method steps are continuously repeated. ### Claim 25 (depends on 24) The method according to claim 24, wherein the time interval between the repetitions of the method steps is within a range of milliseconds.