# US 8,541,728 B1 · Signal monitoring and control system for an optical navigation sensor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,541,728 B1 - Document ID: US8541728B1 - Status: Granted - Kind: B1 - Application number: 13/171,186 - Filed: 2011-06-28 - Granted: 2013-09-24 - Earliest claimed: 2008-09-30 - Assignees: Cypress Semiconductor Corporation - Applicants: Yansun Xu; Steven Sanders; Jahja Trisnadi - Inventors: Yansun Xu; Steven Sanders; Jahja Trisnadi - Web page: https://patentgrep.com/patent/US8541728B1 ## CPC - G01J 1/18: using comparison with a reference electric value - G01J 1/4228: {arrangements with two or more detectors, e.g. for sensitivity compensation} - G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N) ## Abstract A circuit and method are provided to control the strength of signals from an array of photo-detectors in an optical navigation sensor. In one embodiment, the method includes receiving a current signal from an automatic gain control (AGC) photo-detector and generating an AGC signal in response thereto; generating an illumination control signal in response to the AGC signal; and coupling the illumination control signal to an illuminator configured to illuminate at least a portion of an array of photo-detectors with light reflected from a surface to sense displacement of the optical navigation sensor relative to a surface, and adjusting illumination from the illuminator. Other embodiments are also disclosed. ## Claims ### Claim 1 A method of operating an optical navigation sensor comprising: receiving a current signal from an automatic gain control (AGC) photo-detector and generating an AGC signal in response thereto; generating an illumination control signal in response to the AGC signal; and coupling the illumination control signal to an illuminator configured to illuminate at least a portion of an array of photo-detectors with light reflected from a surface to sense displacement of the optical navigation sensor relative to a surface, and adjusting illumination from the illuminator. ### Claim 2 (depends on 1) The method of claim 1 wherein the optical navigation sensor further comprises transimpedance-amplifiers each including an input coupled photo-detectors in the array of photo-detectors to receive current signals therefrom and an output to output a voltage signal generated in response thereto, and further comprising generating an integration time control signal in response to the AGC signal to adjust an integration time of the transimpedance-amplifiers over which the received current signals are integrated to generate the voltage signal. ### Claim 3 (depends on 2) The method of claim 2 wherein the optical navigation sensor further comprises gain amplifiers coupled to the outputs of the transimpedance-amplifiers, and further comprising generating an amplifier gain control signal in response to the AGC signal to adjust gain of the gain amplifiers. ### Claim 4 (depends on 3) The method of claim 3 wherein the optical navigation sensor further comprises a controller coupled to the AGC photo-detector, and wherein generating the illumination control signal, the integration time control signal and the amplifier gain control signal comprises executing in the controller a signal gain adjustment algorithm to generate the illumination control signal, the integration time control signal and the amplifier gain control signal in response to the AGC signal. ### Claim 5 (depends on 2) The method of claim 2 wherein the AGC photo-detector comprises a photo-detector in the array of photo-detectors. ### Claim 6 (depends on 5) The method of claim 5 wherein generating the AGC signal comprises integrating with one of the transimpedance-amplifiers the current signal received from the AGC photo-detector. ### Claim 7 (depends on 2) The method of claim 2 wherein the transimpedance-amplifiers comprise differential transimpedance-amplifiers. ### Claim 8 (depends on 1) The method of claim 1 wherein the AGC photo-detector comprises a photo-detector proximal to and independent of the array of photo-detectors. ### Claim 9 (depends on 1) The method of claim 1 wherein generating the AGC signal comprises integrating with a single ended transimpedance-amplifier the current signal received from the AGC photo-detector. ### Claim 10 A method of operating an optical navigation sensor comprising: receiving a current signal from an automatic gain control (AGC) photo-detector and generating an AGC signal in response thereto; generating an integration time control signal in response to the AGC signal; coupling the integration time control signal to transimpedance-amplifiers each including an input coupled photo-detectors in an array of photo-detectors to receive current signals therefrom and an output to output a voltage signal generated in response thereto; and adjusting an integration time of the transimpedance-amplifiers over which the received current signals are integrated to generate the voltage signal. ### Claim 11 (depends on 10) The method of claim 10 wherein the AGC photo-detector comprises a photo-detector in the array of photo-detectors. ### Claim 12 (depends on 11) The method of claim 11 wherein generating the AGC signal comprises integrating with one of the transimpedance-amplifiers the current signal received from the AGC photo-detector. ### Claim 13 (depends on 10) The method of claim 10 wherein the transimpedance-amplifiers comprise differential transimpedance-amplifiers. ### Claim 14 (depends on 10) The method of claim 10 wherein the AGC photo-detector comprises a photo-detector proximal to and independent of the array of photo-detectors. ### Claim 15 (depends on 10) The method of claim 10 wherein generating the AGC signal comprises integrating with a single ended transimpedance-amplifier the current signal received from the AGC photo-detector. ### Claim 16 (depends on 10) The method of claim 10 wherein the optical navigation sensor further comprises a controller coupled to the AGC photo-detector, and wherein generating the integration time control signal comprises executing in the controller a signal gain adjustment algorithm to generate the integration time control signal in response to the AGC signal. ### Claim 17 (depends on 10) The method of claim 10 wherein the optical navigation sensor further comprises gain amplifiers coupled to the outputs of the transimpedance-amplifiers, and further comprising generating an amplifier gain control signal in response to the AGC signal to adjust gain of the gain amplifiers. ### Claim 18 A method of operating an optical navigation sensor comprising: illuminating at least a portion of an array of photo-detectors with light reflected from a surface; receiving in a plurality of a transimpedance-amplifiers current signals from the array of photo-detectors, each of the plurality of transimpedance-amplifiers including an input coupled to a number of photo-detectors located in a contiguous area of the array different from photo-detectors coupled to another of the plurality of transimpedance-amplifiers; generating from each transimpedance-amplifier an automatic gain control (AGC) signal in response to current signals received from the array of photo-detectors; and determining a spatial distribution of illumination level across the array of photo-detectors using AGC signals from the plurality of transimpedance-amplifiers. ### Claim 19 (depends on 18) The method of claim 18 further comprising generating each trans impedance-amplifier an integration time control signal in response to the AGC signal coupling the integration time control signal to the transimpedance-amplifier, and adjusting an integration time of the transimpedance-amplifier over which current signals received from the array of photo-detectors are integrated. ### Claim 20 (depends on 18) The method of claim 18 wherein the optical navigation sensor further comprises a controller coupled to the plurality of transimpedance-amplifiers, and wherein the controller includes logic to spatial distribution of illumination level across the array of photo-detectors using AGC signals from the plurality of transimpedance-amplifiers.