# US 8,570,304 B2 · Determining touch locations using disturbed light > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,570,304 B2 - Document ID: US8570304B2 - Status: Granted - Kind: B2 - Application number: 13/057,277 - Filed: 2008-09-26 - Published: 2011-06-16 - Granted: 2013-10-29 - Earliest claimed: 2008-09-26 - Assignees: Hewlett-Packard Development Company, L.P. - Applicants: Bradley N. Suggs - Inventors: Bradley N. Suggs - Web page: https://patentgrep.com/patent/US8570304B2 ## CPC - G06F 3/0418: {for error correction or compensation, e.g. based on parallax, calibration or alignment} - G06F 3/0421: {by interrupting or reflecting a light beam, e.g. optical touch-screen} - G06F 3/0423: {using sweeping light beams, e.g. using rotating or vibrating mirror} - 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 A system comprises a plurality of light sources configured to provide light beams to a waveguide layer of a touch-screen. At least one of the light beams is disturbed when an object touches the touch-screen at a touch point. The system also comprises a plurality of detectors, where at least one of the detectors is configured to detect the disturbed light. The system comprises control logic coupled to the at least one detector. The control logic determines a location of the touch point as a result of the at least one detector detecting the disturbed light. The plurality of light sources and plurality of detectors are contained within a source/detector layer. The source/detector layer is separated from the waveguide layer by a mirror layer comprising a plurality of mirrors that transfer light between the source/detector layer and the waveguide layer. ## Claims ### Claim 1 A system, comprising: a plurality of light sources configured to provide light beams to a waveguide layer of a touch-screen, at least one of said light beams is disturbed when an object touches the touch-screen at a touch point; a plurality of detectors, at least one of the detectors configured to detect said disturbed light; and control logic coupled to the at least one detector, the control logic determines a location of said touch point as a result of said at least one detector detecting said disturbed light; wherein the plurality of light sources and plurality of detectors are contained within a source/detector layer, the source/detector layer is separated from the waveguide layer by a mirror layer comprising a plurality of mirrors that transfer light between the source/detector layer and the waveguide layer. ### Claim 2 (depends on 1) The system of claim 1, wherein at least some of the plurality of light sources comprise infrared laser diodes. ### Claim 3 (depends on 1) The system of claim 1, wherein said control logic determines said location by determining which of the plurality of light sources emitted the light beam that was disturbed. ### Claim 4 (depends on 1) The system of claim 1, wherein the plurality of light sources is arranged along a different side of the source/detector layer than the plurality of detectors. ### Claim 5 (depends on 1) The system of claim 1, wherein said disturbed light comprises light dispersed from a light beam emitted by one of said plurality of light sources. ### Claim 6 (depends on 1) The system of claim 1, wherein the plurality of light sources is disposed adjacent to a side of the touch-screen that is orthogonal to another side of the touch-screen adjacent to which said plurality of detectors is disposed. ### Claim 7 (depends on 1) The system of claim 1, wherein an interval between adjacent light sources is between 0.01 mm and 10 mm. ### Claim 8 (depends on 1) The system of claim 1, wherein each of the plurality of light sources is associated with a mirror pair comprising two components, and wherein the mirror pair transfers a light beam from a light source to said touch-screen, the mirror pair spreads the light beam into a range of angles when providing the light beam to the touch-screen. ### Claim 9 (depends on 1) The system of claim 1, wherein, while a first one of the plurality of light sources is activated, each of the plurality of detectors is activated and deactivated, and wherein, while a second one of the plurality of light sources is activated, each of the plurality of detectors is activated and deactivated, the second one of the plurality of light sources is activated while the first one of the plurality of light sources is deactivated. ### Claim 10 (depends on 1) The system of claim 1, wherein all of the plurality of light sources and all of the plurality of detectors are activated within 100 milliseconds. ### Claim 11 A system, comprising: a first layer capable of guiding light waves; a second layer adjacent to the first layer, the second layer comprises multiple reflective devices; a third layer adjacent to the second layer, the third layer comprises multiple light sources and multiple detectors, the light sources arranged on one or more of a pair of sides of the third layer and the detectors arranged on one or more of another pair of sides of the third layer; and control logic coupled to the multiple detectors; wherein each of the light sources is activated so that light passes from that light source to the first layer via one of the multiple reflective devices, each of the light sources is activated and deactivated in a round-robin fashion; wherein, while each of the light sources is activated, each of the multiple detectors is activated and deactivated in a round-robin fashion; wherein, as a result of one of the multiple detectors detecting light, the control logic determines by which of the multiple light sources the detected light was generated. ### Claim 12 (depends on 11) The system of claim 11, wherein said one of the multiple detectors detects said light reflected as a result of frustrated total internal reflection to the first layer at a location that corresponds to said one of the multiple detectors and the light source that generated said detected light. ### Claim 13 (depends on 11) The system of claim 11, wherein the pair of sides is orthogonal to the another pair of sides. ### Claim 14 (depends on 11) The system of claim 11, wherein a total amount of time for each of the multiple light sources to be activated and deactivated in a round-robin fashion, and for each of the multiple detectors to be activated and deactivated in a round-robin fashion, is less than 100 milliseconds. ### Claim 15 (depends on 11) The system of claim 11, wherein said light that passes from the light source to the first layer via one of the multiple reflective devices travels through said first layer in a light beam that runs parallel to said another pair of sides. ### Claim 16 (depends on 11) The system of claim 11, wherein the system comprises a system selected from the group consisting of a display, a television, a desktop computer system, a mobile communication device, a personal digital assistant and a portable music player. ### Claim 17 A method, comprising: generating a light beam that propagates along a length of a display using total internal reflection; frustrating the total internal reflection of the light beam so as to leak at least part of said light beam; activating and deactivating each of a plurality of detectors until one of said detectors detects a reflected portion of said leaked light; and using a location of the detector that detects said reflected portion of the leaked light and a location of a light source that generated said light beam, determining one or more locations at which said total internal reflection of the light beam was frustrated. ### Claim 18 (depends on 17) The method of claim 17, wherein generating said light beam along said length comprises using the light source to generate said light beam, providing said light beam to a pair of mirrors, and introducing said light beam from the pair of mirrors into the display, said display comprises a layer of glass capable of guiding waveforms. ### Claim 19 (depends on 17) The method of claim 17 further comprising providing said one or more locations to a processor that is executing an application and that is displaying a graphical user interface (GUI) associated with said application. ### Claim 20 (depends on 17) The method of claim 17, wherein generating said light beam comprises using infrared laser diodes. ### Claim 21 A system, comprising: a light source and detector layer (LSDL) comprising a plurality of light sources disposed along at least one of a pair of sides of the LSDL and further comprising a plurality of detectors disposed along at least one of another pair sides of the LSDL; a mirror layer adjacent to said LSDL, the mirror layer comprising multiple mirror pairs, at least one of said multiple mirror pairs aligned with one of the plurality of light sources, at least another one of said mirror pairs aligned with one of the plurality of detectors; and a glass layer adjacent to said mirror layer, the glass layer at least partially separated from the LSDL by the mirror layer. ### Claim 22 (depends on 21) The system of claim 21, wherein the plurality of light sources are aligned with a single mirror pair that reflects light emitted from the plurality of light sources into the glass layer. ### Claim 23 (depends on 21) The system of claim 21, wherein the plurality of detectors are aligned with a single mirror pair that reflects light from the glass layer to said plurality of detectors. ### Claim 24 (depends on 21) The system of claim 21, wherein the plurality of light sources are spaced between 1 mm and 10 mm apart. ### Claim 25 (depends on 21) The system of claim 21, wherein the system comprises a computer display.