# US 2017/0255337 A1 · Instrument Detection with an Optical Touch Sensitive Device, with Associating Contacts with Active Instruments > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0255337 A1 - Document ID: US20170255337A1 - Status: Published application - Kind: A1 - Application number: 15/603,310 - Filed: 2017-05-23 - Published: 2017-09-07 - Earliest claimed: 2014-09-02 - Assignees: Rapt IP Limited - Applicants: Rapt IP Limited - Inventors: Owen Drumm - Web page: https://patentgrep.com/patent/US20170255337A1 ## CPC - G06F 3/0421: {by interrupting or reflecting a light beam, e.g. optical touch-screen} - G06F 3/0346: with detection of the device orientation or free movement in a three-dimensional [3D] space, e.g. 3D mice, 6-DOF [six degrees of freedom] pointers using gyroscopes, accelerometers or tilt-sensors - G06F 3/03542: {Light pens for emitting or receiving light} - G06F 3/038: Control and interface arrangements therefor, e.g. drivers or device-embedded control circuitry - G06F 3/0386: {for light pen} - G06F 3/0416: {Control or interface arrangements specially adapted for digitisers} - G06F 3/0428: {by sensing at the edges of the touch surface the interruption of optical paths, e.g. an illumination plane, parallel to the touch surface which may be virtual (sensing beam interruptions in a planar beam grid of an optical touch-screen G06F3/0421)} - G06F 3/0488: using a touch-screen or digitiser, e.g. input of commands through traced gestures - G06F 2203/04104: Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger - G06F 2203/04106: Multi-sensing digitiser, i.e. digitiser using at least two different sensing technologies simultaneously or alternatively, e.g. for detecting pen and finger, for saving power or for improving position detection - G06F 2203/04109: FTIR in optical digitiser, i.e. touch detection by frustrating the total internal reflection within an optical waveguide due to changes of optical properties or deformation at the touch location - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract An optical touch-sensitive device detects touch events caused by instruments (e.g., pens, styluses) and distinguishes these events from touch events caused by fingers. In some embodiments, different instruments can also be distinguished. The optical touch-sensitive device includes multiple emitters and detectors. Each emitter produces optical beams which are received by the detectors. The optical beams preferably are multiplexed in a manner so that many optical beams can be received by a detector simultaneously. Touch events disturb the optical beams, for example due to frustrated total internal reflection. Information indicating which optical beams have been disturbed is analyzed to detect one or more touch events. The analysis also distinguishes instrument touch events from finger touch events. ## Claims ### Claim 1 A method for making an association between an active instrument and a detected touch event on a touch-sensitive surface, the method comprising: receiving information specific to each of one or more detected touch events; receiving information specific to an active instrument; analyzing the information specific to the active instrument with the information specific to the detected touch events for consistency with a situation in which the active instrument caused one of the detected touch events; and making an association between the active instrument and one of the detected touch events based on said analysis. ### Claim 2 (depends on 1) The method of claim 1, wherein a plurality of emitters and a plurality of detectors are arranged around the touch-sensitive surface's periphery, optical beams propagate from the plurality of emitters to the plurality of detectors by total internal reflection in an optical waveguide, the method further comprising: detecting locations for the detected touch events based on disturbances of the optical beams as a result of frustrated total internal reflection coupling energy out of the optical waveguide at the detected touch events. ### Claim 3 (depends on 2) The method of claim 2, wherein: the information specific to each of the detected touch events comprises transmittance of the optical beams disturbed by the detected touch event; the information specific to the active instrument comprises a strength of optical coupling between the active instrument and the optical waveguide; and analyzing the information specific to the active instrument with the information specific to the detected touch events comprises determining consistency between the transmittance of the optical beams disturbed by the detected touch events and the strength of optical coupling between the active instrument and the optical waveguide. ### Claim 4 (depends on 3) The method of claim 3, wherein the active instrument injects light into the optical waveguide, the method further comprising: determining the strength of optical coupling between the active instrument and the optical waveguide based on coupling of the light injected from the active instrument into the optical waveguide. ### Claim 5 (depends on 3) The method of claim 3, wherein the active instrument detects optical beams coupled out of the optical waveguide, the method further comprising: determining the strength of optical coupling between the active instrument and the optical waveguide based on the optical beams coupled out of the optical waveguide by frustrated total internal reflection and into the active instrument. ### Claim 6 (depends on 3) The method of claim 3, wherein: the information specific to each of the detected touch events comprises time variation of transmittance of the optical beams disturbed by the detected touch event; the information specific to the active instrument comprises time variation of a strength of optical coupling between the active instrument and the optical waveguide; and analyzing the information specific to the active instrument with the information specific to the detected touch events comprises determining consistency between the time variation of transmittance of the optical beams disturbed by the detected touch events and the time variation of the strength of optical coupling between the active instrument and the optical waveguide. ### Claim 7 (depends on 2) The method of claim 2, wherein the information specific to each of the detected touch events comprises a movement over time of the detected touch event; the information specific to the active instrument comprises a movement over time of the active instrument; and analyzing the information specific to the active instrument with the information specific to the detected touch events comprises determining consistency between the movement of the detected touch events and the movement of the active instrument. ### Claim 8 (depends on 7) The method of claim 7, wherein the movement of the active instrument is captured by a motion sensor in the active instrument. ### Claim 9 (depends on 8) The method of claim 8, wherein receiving the information specific to the active instrument occurs on a delayed basis. ### Claim 10 (depends on 2) The method of claim 2, wherein the information specific to each of the detected touch events comprises a location of the detected touch event; the active instrument injects light into the optical waveguide according to an emission pattern, and the information specific to the active instrument comprises the emission pattern for the active instrument and further comprises a pattern of the injected light detected by the plurality of detectors; and analyzing the information specific to the active instrument with the information specific to the detected touch events comprises determining consistency between the pattern of injected light that is actually detected and the patterns that would be produced by the emission pattern centered at the locations of the detected touch events. ### Claim 11 (depends on 10) The method of claim 10, wherein determining consistency between the pattern of injected light that is actually detected and the patterns that would be produced by the emission pattern centered at the locations of the detected touch events comprises: using templates for the patterns that would be produced by the emission pattern centered at different locations. ### Claim 12 (depends on 10) The method of claim 10, wherein determining consistency between the pattern of injected light that is actually detected and the patterns that would be produced by the emission pattern centered at the locations of the detected touch events comprises: estimated an approximate location for the active instrument based on the emission pattern for the active instrument and the actual pattern of injected light detected by the plurality of detectors; and determining consistency between the estimated approximate location for the active instrument and the locations of the detected touch events. ### Claim 13 (depends on 10) The method of claim 10, wherein: the information specific to each of the detected touch events comprises time variation of location of the detected touch event; the active instrument injects light into the optical waveguide according to an emission pattern, and the information specific to the active instrument comprises the emission pattern for the active instrument and further comprises a time variation of a pattern of the injected light detected by the plurality of detectors; and analyzing the information specific to the active instrument with the information specific to the detected touch events comprises determining consistency between the time variation of the pattern of injected light that is actually detected and the time variations of the patterns that would be produced by the emission pattern centered at the time-varying locations of the detected touch events. ### Claim 14 (depends on 2) The method of claim 2, wherein the active instrument injects light into the optical waveguide according to an emission pattern, the method further comprising: identifying the active instrument based on the injected light detected by the plurality of detectors in comparison to the emission pattern. ### Claim 15 (depends on 14) The method of claim 14, wherein the emission pattern includes spatial variation of the injected light as a function of angle. ### Claim 16 (depends on 14) The method of claim 14, wherein the emission pattern includes intensity modulation of the injected light over time. ### Claim 17 (depends on 14) The method of claim 14, wherein the emission pattern includes wavelength variation of the injected light over time. ### Claim 18 (depends on 14) The method of claim 14, wherein the emission pattern includes spatial variation of the injected light over time. ### Claim 19 (depends on 2) The method of claim 2, wherein the active instrument injects light into the optical waveguide according to an emission pattern, the method further comprising: determining an orientation of the active instrument based on the injected light detected by the plurality of detectors in comparison to the emission pattern. ### Claim 20 A non-transitory computer-readable medium comprising computer program instructions that when executed by a processor of a touch-sensitive device causes the processor to perform steps comprising: receiving information specific to each of one or more detected touch events; receiving information specific to an active instrument; analyzing the information specific to the active instrument with the information specific to the detected touch events for consistency with a situation in which the active instrument caused one of the detected touch events; and making an association between the active instrument and one of the detected touch events based on said analysis. ### Claim 21 An optical touch-sensitive device comprising: a surface for which one or more touch events are to be detected; a detector configured to detect the one or more touch events; and a touch event processor coupled, directly or indirectly, to the detector, the touch event processor configured to perform steps comprising: receiving information specific to each of the one or more detected touch events, receiving information specific to an active instrument, analyzing the information specific to the active instrument with the information specific to the detected touch events for consistency with a situation in which the active instrument caused one of the detected touch events, and making an association between the active instrument and one of the detected touch events based on said analysis.