# US 11,451,263 B2 · Unconnected paired plate capacitive coupling for touch detection and communication > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,451,263 B2 - Document ID: US11451263B2 - Status: Granted - Kind: B2 - Application number: 16/621,651 - Filed: 2018-06-22 - Published: 2021-05-20 - Granted: 2022-09-20 - Earliest claimed: 2017-06-22 - Assignees: Enpointe Fencing Pty Ltd - Applicants: Enpointe Fencing Pty Ltd - Inventors: Callum Laurenson; Tony Grubman - Web page: https://patentgrep.com/patent/US11451263B2 ## CPC - G06F 21/32: using biometric data, e.g. fingerprints, iris scans or voiceprints - G06F 3/044: by capacitive means - H04B 5/22: Capacitive coupling - H04B 5/70: specially adapted for specific purposes - H04B 5/73: for taking measurements, e.g. using sensing coils - A63B 69/02: for fencing {, e.g. means for indicating hits} - A63B 71/0605: {Decision makers and devices using detection means facilitating arbitration} - A63B 2225/50: Wireless data transmission, e.g. by radio transmitters or telemetry - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - H04B: TRANSMISSION - A63B: APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT (apparatus for passive exercising, massage A61H) ## Abstract There is provided herein circuitry and methods for applications including touch detection and, in embodiments, low rate communication such as for secure device authentication. The method uses a circuit having a first device having a first pair of unconnected plates and an edge source coupled therebetween. The circuit further comprises a second device having a second pair of respective unconnected plates and a charge sensor coupled therebetween. The method for touch detection comprises applying at least one differential edge between the first pair of unconnected plates using the edge source and detecting touch by coherently (i.e. in time) sensing an imbalance in a near field channel formed between the plates and an output signal of the charge sensor. The present method/circuit has various applications including for touch detection in fencing and secure device authentication employing both touch detection and bidirectional cryptographic communication between key and secure devices. ## Claims ### Claim 1 A method for touch detection comprising employing a circuit comprising: a first device having a first pair of unconnected plates and an edge source coupled therebetween; a second device having a second pair of respective unconnected plates and a charge sensor coupled therebetween wherein the first device and the second device are provided without sharing a common ground, the method comprising: applying at least one differential edge between the first pair of unconnected plates using the edge source; and coherently sensing an imbalance in a near field channel formed between the first pair of plates using an output signal of the charge sensor to detect touch, wherein the edge source provides a current pulse transmitted through the near field channel. ### Claim 2 (depends on 1) A method as claimed in claim 1, wherein the method further comprises encoding information in the at least one differential edge and decoding the information using from the output signal of the charge sensor. ### Claim 3 (depends on 2) A method as claimed in claim 2, wherein processing gain is used for the encoding and decoding. ### Claim 4 (depends on 1) A method as claimed in claim 1, wherein the first device is a low impedance transmitter. ### Claim 5 (depends on 1) A method as claimed in claim 1, wherein the edge source is controlled to transmit a sequence of differential edges. ### Claim 6 A method as claimed in 1, wherein the charge sensor has a low input impedance. ### Claim 7 (depends on 6) A method as claimed in claim 6, wherein the charge sensor comprises a transimpedance amplifier. ### Claim 8 (depends on 7) A method as claimed in claim 7, wherein the charge sensor comprises a regulated cascode transimpedance amplifier. ### Claim 9 (depends on 6) A method as claimed in claim 6, wherein the charge sensor comprises a resettable charge amplifier configured to integrate charge over a duration of a current pulse. ### Claim 10 (depends on 1) A method as claimed in claim 1, wherein the output of the charge sensor is operably coupled to an analogue-to-digital converter. ### Claim 11 (depends on 10) A method as claimed in claim 10, wherein the output of the charge sensor is sampled according to a transmission period of the at least one differential edge. ### Claim 12 (depends on 1) A method as claimed in claim 1, further comprising transmitting timing information out-of-band and controlling sampling of the second device according to the timing information. ### Claim 13 (depends on 1) A method as claimed in claim 1, wherein the second device is configured to determine when to sample the output signal according to a signal characteristic of the output signal. ### Claim 14 (depends on 1) A method as claimed in claim 1, further comprising measuring a current path direction between the second pair of plates to determine which plate of the second device is more strongly coupled to a plate of the first device. ### Claim 15 (depends on 1) A method as claimed in claim 1, wherein the circuit further comprises: a further edge source coupled between the second pair of plates; and a further charge sensor coupled between the first pair of plates, the method comprising: applying at least one further differential edge between the second pair of unconnected plates using the further edge source and detecting touch by coherently detecting an imbalance in the near field channel formed between the plates using a further output signal of the further charge sensor. ### Claim 16 (depends on 15) A method as claimed in claim 15, further comprising applying the at least one differential edge and the at least one further differential edge alternately. ### Claim 17 (depends on 16) A method as claimed in claim 16, further comprising controlling the devices to time division multiplex the at least one differential edge and the at least one further differential edge. ### Claim 18 (depends on 1) A method as claimed in claim 1, wherein the first device has a further pair of unconnected plates and wherein the method comprises applying at least one differential edge alternately between the first pair and the further pair. ### Claim 19 (depends on 1) A method as claimed in claim 1, wherein the second device has a further pair of unconnected plates and wherein the method comprises receiving the output signal alternately from the second pair and the further pair. ### Claim 20 (depends on 1) A method as claimed in claim 1, wherein the plates provide a shield between non-respective plates of the first and second pairs to are shaped to shield parasitic capacitance between non-respective plates of the first and second pairs. ### Claim 21 (depends on 1) A method as claimed in claim 1, wherein the circuit is used for touch detection for fencing. ### Claim 22 (depends on 21) A method as claimed in claim 21, wherein the circuit is placed close to a player body, and wherein plates comprise a weapon, a weapon tip, a lame, and a local pad, the local pad coupling to a player body. ### Claim 23 (depends on 22) A method as claimed in claim 22 wherein an additional pad is used for coupling a surrounding environment. ### Claim 24 (depends on 21) A method as claimed in claim 21, wherein a player body is coupled to a weapon grip and wherein plates comprise a weapon, a grip and a weapon tip. ### Claim 25 (depends on 24) A method as claimed in claim 24, wherein the circuit is housed within a guard of a weapon. ### Claim 26 (depends on 21) A method as claimed in claim 21, wherein a signal is transmitted via a piste for floor hit detection. ### Claim 27 (depends on 1) A method as claimed in claim 1, wherein the circuit is further used for secure device authentication. ### Claim 28 (depends on 27) A method as claimed in claim 27, further comprising using the first device as a key device and the second device as a secure device and wherein: one of the plates of the key device is located closer to a body of a user; and one of the plates of the secure device is located for touching by the body of the user for authorising the key device and another of the plates of the secure device couples another of the plates of the key device via a field path. ### Claim 29 (depends on 28) A method as claimed in claim 28, wherein both of the key and secure devices comprise edge sources for transmitting and charge sensors for receiving and wherein the method further comprises alternating the devices in turn between transmitting and receiving. ### Claim 30 (depends on 28) A method as claimed in claim 28, further comprising measuring a round trip transmission propagation delay between the key and secure devices. ### Claim 31 (depends on 28) A method as claimed in claim 28, further comprising authentication by transmitting a cryptographic challenge between the key and secure devices and receiving a response between the key and secure devices. ### Claim 32 (depends on 31) A method as claimed in claim 31, further comprising shortening symbol time for distance bounding. ### Claim 33 (depends on 32) A method as claimed in claim 32, further comprising using cryptographic processing gain for at least one of secure sensitivity improvement and secure noise immunity. ### Claim 34 (depends on 28) A method as claimed in claim 28, wherein the method further comprises capacitive sensing to determine which plate of the key device plates is closest to a user's body to determine orientation of the key device. ### Claim 35 (depends on 34) A method as claimed in claim 34, further comprising verifying direction of a dominant field path with respect to the orientation for preventing unauthorised access by proximal bodies.