# US 12,181,612 B2 · Optical sensor diagnostics > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,181,612 B2 - Document ID: US12181612B2 - Status: Granted - Kind: B2 - Application number: 17/203,382 - Filed: 2021-03-16 - Published: 2021-09-23 - Granted: 2024-12-31 - Earliest claimed: 2020-03-20 - Assignees: Melexis Technologies SA - Applicants: Melexis Technologies NV - Inventors: Hans Van Den Broeck - Web page: https://patentgrep.com/patent/US12181612B2 ## CPC - G01S 7/497: Means for monitoring or calibrating - G01S 17/08: for measuring distance only (indirect measurement G01S17/46; active triangulation systems G01S17/48) - H04N 13/204: using stereoscopic image cameras (stereoscopic photography G03B35/00) - H04N 17/002: {for television cameras} - H04N 23/73: by influencing the exposure time - H04N 25/671: for non-uniformity detection or correction - H04N 25/705: Pixels for depth measurement, e.g. RGBZ - H04N 2013/0081: {Depth or disparity estimation from stereoscopic image signals} - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract A method for diagnosing an optical sensor includes a photodetector and an integrator. The method comprises exposing the photodetector to incoming light; obtaining an initial integrated signal at an initial frame; at least once executing the steps of changing at least one control parameter of the optical sensor, exposing the photodetector to incoming light, and obtaining one or more subsequent integrated signals at a subsequent frame; obtaining a characteristic of the optical sensor from the obtained integrated signals; comparing the obtained characteristic with a pre-determined characteristic of the optical sensor to diagnose the optical sensor. ## Claims ### Claim 1 A method for diagnosing an optical sensor which comprises a photodetector and an integrator, the method comprising: exposing the photodetector to incoming light; obtaining an initial integrated signal at an initial frame; at least once executing the steps of changing at least one control parameter of the optical sensor, exposing the photodetector to incoming light, and obtaining one or more subsequent integrated signals at a subsequent frame; wherein integrated signals are obtained per frame for each pixel, and a frame comprises at least one sequence of resetting the optical sensor and accumulating, during an integration time, a signal from circuitry which connects the photodetector with the integrator, and reading the integrated signal wherein the integrated signal is representative for the amount of incoming light on the photodetector and is a calculated voltage difference between an output voltage before and after the integration time; obtaining a characteristic of the optical sensor from the obtained integrated signals; and comparing the obtained characteristic with a pre-determined characteristic of the optical sensor, wherein the pre-determined characteristic is defined in function of the at least one control parameter, to diagnose the optical sensor to detect if a fault is present in each pixel of the optical sensor. ### Claim 2 (depends on 1) The method according to claim 1, wherein at least one control parameter is the integration time. ### Claim 3 (depends on 2) The method according to claim 2, wherein the integration times have a ratio ranging from 50% to 150%. ### Claim 4 (depends on 1) The method according to claim 1, wherein at least one control parameter is the gain of the optical sensor. ### Claim 5 (depends on 1) The method according to claim 1, wherein the integrated signal Vout(t) is modelled as g*t+Voffset, wherein g and Voffset are characteristics of the optical sensor which are obtained from the obtained integrated signals. ### Claim 6 (depends on 1) The method according to claim 1, wherein a characteristic of the optical sensor is obtained by dividing subsequent integrated signals. ### Claim 7 (depends on 1) A computer program product for, if implemented on a processing unit, performing the method for diagnosing an optical sensor according to claim 1. ### Claim 8 An optical sensor, the optical sensor comprising a photodetector, an integrator, and circuitry connecting the photodetector with the integrator such that a signal from the photodetector, or a processed version thereof, can be accumulated on the integrator, the optical sensor comprising a controller configured for: obtaining an initial integrated signal at an initial frame; at least once executing the steps of changing at least one control parameter of the optical sensor, and obtaining one or more subsequent integrated signals at a subsequent frame; wherein integrated signals are obtained per frame for each pixel, and a frame comprises at least one sequence of resetting the optical sensor and accumulating, during an integration time, a signal from the circuitry which connects the photodetector with the integrator, and reading the integrated signal wherein the integrated signal is representative for the amount of incoming light on the photodetector and is a calculated voltage difference between an output voltage before and after the integration time; obtaining a characteristic of the optical sensor from the obtained integrated signals; and comparing the obtained characteristic with a pre-determined characteristic of the optical sensor, wherein the pre-determined characteristic is defined in function of the at least one control parameter, to diagnose the optical sensor to detect if a fault is present in each pixel of the optical sensor. ### Claim 9 (depends on 8) The optical sensor according to claim 8, wherein the integrator comprises a plurality of parallel capacitors wherein the controller is configured for connecting or disconnecting one or more of the capacitors of the integrator. ### Claim 10 (depends on 9) The optical sensor according to claim 9, wherein the optical sensor further comprises a gain transistor configured for connecting or disconnecting a capacitor from the plurality of parallel capacitors of the integrator. ### Claim 11 (depends on 8) The optical sensor according to claim 8, wherein the optical sensor further comprises a reset transistor configured for resetting the integrator voltage. ### Claim 12 (depends on 8) An indirect Time-of-Flight system for measuring the time of flight of a modulated optical signal which is reflected on an object, the indirect Time-of-Flight system comprising an optical sensor according to claim 8, for receiving the reflected optical signal, wherein the Time-of-Flight system is configured for obtaining a measure of the time-of-flight and wherein this measure is the characteristic of the optical sensor for diagnosing the optical sensor. ### Claim 13 (depends on 12) The indirect Time-of-Flight system according to claim 12, wherein the circuitry connecting the photodetector with the integrator comprises a mixer configured for mixing a signal from the photodetector with a signal which is phase correlated with the modulated optical signal with such that the mixed signal can be accumulated on the integrator. ### Claim 14 A camera comprising a plurality of pixels, each pixel comprising a photodetector, an integrator, and circuitry connecting the photodetector with the integrator the camera comprising a controller which is for each of the pixels configured for: obtaining an initial integrated signal at an initial frame; at least once executing the steps of changing at least one control parameter of the camera, and obtaining one or more subsequent integrated signals at a subsequent frame; wherein integrated signals are obtained per frame for each pixel, and a frame comprises at least one sequence of resetting the optical sensor and accumulating, during an integration time, a signal from the circuitry which connects the photodetector with the integrator, and reading the integrated signal wherein the integrated signal is representative for the amount of incoming light on the photodetector and is a calculated voltage difference between an output voltage of the optical sensor before and after the integration time; obtaining a characteristic of the optical sensor from the obtained integrated signals; and comparing the obtained characteristic with a pre-determined characteristic of the optical sensor, wherein the pre-determined characteristic is defined in function of the at least one control parameter, to diagnose the optical sensor to detect if a fault is present in each pixel of the optical sensor. ### Claim 15 (depends on 14) The camera according to claim 14, wherein the camera is a 3D-camera and wherein the controller is configured for obtaining a pixel depth for each pixel as characteristic of the pixel, and wherein comparing the obtained characteristic with the pre-determined characteristic corresponds with verifying that the pixel depth does not significantly change for each pixel.