# US 2014/0152582 A1 · Noise correction for stylus applications on tablets and other touch devices > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0152582 A1 - Document ID: US20140152582A1 - Status: Published application - Kind: A1 - Application number: 13/691,637 - Filed: 2012-11-30 - Published: 2014-06-05 - Earliest claimed: 2012-11-30 - Assignees: Apple Inc. - Applicants: Apple Inc. - Inventors: Manu Agarwal; Shahrooz Shahparnia; Martin Paul Grunthaner - Web page: https://patentgrep.com/patent/US20140152582A1 ## CPC - G06F 3/0442: {using active external devices, e.g. active pens, for transmitting changes in electrical potential to be received by the digitiser} - G06F 3/033: Pointing devices displaced or positioned by the user {, e.g. mice, trackballs, pens or joysticks}; Accessories therefor (digitisers characterised by the transducing means G06F3/041) - G06F 3/03545: {Pens or stylus} - G06F 3/0418: {for error correction or compensation, e.g. based on parallax, calibration or alignment} - G06F 3/0443: {using a single layer of sensing electrodes} - G06F 3/0445: {using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer} - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract A touch sensitive device capable of detecting signals generated by a stylus and correcting the detected stylus signals for effects due to noise present on the device is disclosed. In one example, signals are taken from one or more electrodes that are a pre-determined distance away from an electrode in which a stylus signal is detected. The pre-determined distance can be empirically determined such that a noise estimate can be generated such that the electrodes have a higher probability of containing only noise that is highly correlated to the noise present on a detected stylus signal. The generated noise estimate is then subtracted from a detected stylus signal to reduce the effect of noise on the stylus signal. ## Claims ### Claim 1 A stylus detection apparatus for detecting contacts from a stylus, the apparatus comprising: a touch sensor panel comprising a plurality of electrodes, each electrode configured to receive one or more signals from a stylus; and a processor, the processor capable of: measuring a first signal from a first electrode; measuring one or more signals from a pre-determined number of second electrodes; generating a noise estimate based on the measured one or more signals from the pre-determined number of second electrodes; and adjusting the measured first signal based on at least the generated noise estimate. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein measuring one or more signals from a pre-determined number of second electrodes includes measuring a second signal from a second electrode, wherein the second electrode is a predetermined number of electrodes away from the first electrode. ### Claim 3 (depends on 1) The apparatus of claim 1, wherein the pre-determined number of second electrodes are further selected so first and second groups of the pre-determined number of second electrodes are adjacent to and on opposite sides of the first electrode, and wherein the number of electrodes in the first group is equal to the number of electrodes in the second group. ### Claim 4 (depends on 1) The apparatus of claim 1, wherein the pre-determined number of second electrodes are further selected such that they are closest to an edge of the apparatus that is closest to a determined location of the stylus. ### Claim 5 (depends on 1) The apparatus of claim 1, wherein the predetermined number of electrodes is based at least in part on a physical dimension of the stylus. ### Claim 6 (depends on 5) The apparatus of claim 5, wherein the predetermined number of electrodes is based on a width of the stylus tip. ### Claim 7 (depends on 1) The apparatus of claim 1, wherein the predetermined number of electrodes is based in part on a noise signal received by the touch sensor panel. ### Claim 8 (depends on 1) The apparatus of claim 1, wherein adjusting the measured first signal based on at least the generated noise estimate includes subtracting the noise estimate from the measured first signal. ### Claim 9 A method of correcting a detected stylus signal for the effects of noise, the method comprising: detecting a first stylus signal from a first electrode of a touch sensor panel; measuring one or more signals from a pre-determined number of second electrodes; generating a noise estimate based on the measured one or more signals from the pre-determined number of second electrodes; and adjusting the measured first signal based on at least the generated noise estimate. ### Claim 10 (depends on 9) The method of claim 9, wherein measuring one or more signals from a pre-determined number of second electrodes includes measuring a second signal from a second electrode, wherein the second electrode is a predetermined number of electrodes away from the first electrode. ### Claim 11 (depends on 9) The method of claim 9, wherein the pre-determined number of second electrodes are further selected so first and second groups of the pre-determined number of second electrodes are adjacent to and on opposite sides of the first electrode, and wherein the number of electrodes in the first group is equal to the number of electrodes in the second group. ### Claim 12 (depends on 9) The method of claim 9, wherein the pre-determined number of second electrodes are further selected such that they are closest to an edge of the apparatus that is closest to a determined location of the stylus. ### Claim 13 (depends on 9) The method of claim 9, wherein the predetermined number of electrodes is based at least in part on a physical dimension of the stylus. ### Claim 14 (depends on 13) The method of claim 13, wherein the predetermined number of electrodes is based on a width of the stylus tip. ### Claim 15 (depends on 9) The method of claim 9, wherein the predetermined number of electrodes is based in part on a noise signal received by the touch sensor panel. ### Claim 16 (depends on 9) The apparatus of claim 9, wherein adjusting the measured first signal based on at least the generated noise estimate includes subtracting the noise estimate from the measured first signal. ### Claim 17 A non-transitory computer readable storage medium having stored thereon a set of instructions for detecting a stylus signal and correcting the stylus signal for effects caused by noise in a touch sensor panel that when executed by a processor causes the processor to: detect a first stylus signal from a first electrode of a touch sensor panel; measure one or more signals from a pre-determined number of second electrodes; generate a noise estimate based on the measured one or more signals from the pre-determined number of second electrodes; and adjust the measured first signal based on at least the generated noise estimate. ### Claim 18 (depends on 17) The non-transitory computer readable storage medium of claim 17, wherein measuring one or more signals from a pre-determined number of second electrodes includes measuring a second signal from a second electrode, wherein the second electrode is a predetermined number of electrodes away from the first electrode. ### Claim 19 (depends on 17) The non-transitory computer readable storage medium of claim 17, wherein the pre-determined number of second electrodes are further selected so first and second groups of the pre-determined number of second electrodes are adjacent to and on opposite sides of the first electrode, and wherein the number of electrodes in the first group is equal to the number of electrodes in the second group. ### Claim 20 (depends on 17) The non-transitory computer readable storage medium of claim 17, wherein the pre-determined number of second electrodes are further selected such that they are closest to an edge of the apparatus that is closest to a determined location of the stylus. ### Claim 21 (depends on 17) The non-transitory computer readable storage medium of claim 17, wherein the predetermined number of electrodes is based at least in part on a physical dimension of the stylus. ### Claim 22 (depends on 21) The non-transitory computer readable storage medium of claim 21, wherein the predetermined number of electrodes is based on a width of the stylus tip. ### Claim 23 (depends on 17) The non-transitory computer readable storage medium of claim 17, wherein the predetermined number of electrodes is based in part on a noise signal received by the touch sensor panel. ### Claim 24 (depends on 17) The non-transitory computer readable storage medium of claim 17, wherein adjusting the measured first signal based on at least the generated noise estimate includes subtracting the noise estimate from the measured first signal.