# US 11,310,445 B2 · Dynamic vision sensor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,310,445 B2 - Document ID: US11310445B2 - Status: Granted - Kind: B2 - Application number: 17/215,729 - Filed: 2021-03-29 - Published: 2021-07-15 - Granted: 2022-04-19 - Earliest claimed: 2018-09-29 - Assignees: Huawei Technologies Co., Ltd. - Applicants: Huawei Technologies Co., Ltd. - Inventors: Zhaolei Xiao; Jiantong Zhou; Yuntan Fang; Shan Gao; Zhenhua Wu; Jing Xiao - Web page: https://patentgrep.com/patent/US11310445B2 ## CPC - H04N 25/00: Circuitry of solid-state image sensors [SSIS]; Control thereof - H04N 25/78: Readout circuits for addressed sensors, e.g. output amplifiers or A/D converters - H04N 25/47: Image sensors with pixel address output; Event-driven image sensors; Selection of pixels to be read out based on image data - H04N 25/707: Pixels for event detection - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract This application provides a dynamic vision sensor. The sensor converts an optical signal into an electrical signal by using a photoelectric conversion unit, to generate a photovoltage; performs second-order difference on the photovoltage by using a second-order differential circuit; and generates a second-order event signal based on a result of second-order difference. A camera including the sensor can generate an image based on the second-order event signal, where the image represents a change of a light change speed. ## Claims ### Claim 1 A sensor, comprising: a photoelectric converter, configured to convert a received optical signal into an electrical signal, to generate a photovoltage; a second-order differential circuit, configured to perform second-order differential processing on the photovoltage, to generate a second-order differential voltage; and a comparison circuit, configured to: compare the second-order differential voltage with a second-order comparison threshold, to determine a comparison result; and generate a second-order event signal based on the comparison result. ### Claim 2 (depends on 1) The sensor according to claim 1, wherein the second-order differential voltage comprises a non-zero second-order differential voltage or a zero second-order differential voltage; and wherein the second-order differential circuit being configured to perform second-order difference on the photovoltage, to generate the second-order differential voltage comprises the second-order differential circuit being configured to: when a change speed of a photovoltage at a current moment is different from a change speed of a photovoltage at a previous moment, generate the non-zero second-order differential voltage; or when a change speed of a photovoltage at a current moment is the same as a change speed of a photovoltage at a previous moment, generate the zero second-order differential voltage. ### Claim 3 (depends on 1) The sensor according to claim 1, wherein the second-order differential circuit comprises: a sample-and-hold circuit, configured to convert the photovoltage into a differential input voltage; and a second-order differential sub-circuit, configured to perform second-order differential processing on the photovoltage based on the differential input voltage, to generate the second-order differential voltage. ### Claim 4 (depends on 3) The sensor according to claim 3, wherein the differential input voltage comprises a plurality of voltages, and voltages of the plurality of voltages correspond on a one-to-one basis to photovoltages at a plurality of different moments. ### Claim 5 (depends on 3) The sensor according to claim 3, wherein: the second-order differential sub-circuit comprises a first first-order differential circuit and a second first-order differential circuit connected in series; the first first-order differential circuit is configured to generate a first first-order differential voltage and a second first-order differential voltage based on the differential input voltage; and the second first-order differential circuit is configured to generate the second-order differential voltage based on the first first-order differential voltage and the second first-order differential voltage. ### Claim 6 (depends on 5) The sensor according to claim 5, wherein the comparison circuit is further configured to: compare the first first-order differential voltage or the second first-order differential voltage with a first-order comparison threshold to generate a second comparison result; and generate a first-order event signal based on the second comparison result. ### Claim 7 (depends on 5) The sensor according to claim 5, wherein the comparison circuit is further configured to: separately compare the first first-order differential voltage and the second first-order differential voltage with a first-order comparison threshold, generate a first first-order event signal based on a comparison result of the first first-order differential voltage; and generate a second first-order event signal based on a comparison result of the second first-order differential voltage. ### Claim 8 (depends on 5) The sensor according to claim 5, wherein the second-order differential circuit further comprises: a gating circuit, configured to: when a preset condition is satisfied, control the second first-order differential circuit to generate the second-order differential voltage based on the first first-order differential voltage and the second first-order differential voltage. ### Claim 9 (depends on 1) The sensor according to claim 1, further comprising: a readout circuit; and wherein the photoelectric converter is further configured to send the photovoltage to the readout circuit; and wherein the readout circuit is configured to perform integration on the photovoltage, to generate an integral voltage signal. ### Claim 10 An apparatus, comprising: a sensor array, comprising a plurality of sensors, wherein each sensor of the plurality of sensors comprises: a respective photoelectric converter, configured to convert a received optical signal into an electrical signal, to generate a respective photovoltage; a respective second-order differential circuit, configured to perform second-order differential processing on the respective photovoltage, to generate a respective second-order differential voltage; and a respective comparison circuit, configured to: compare the respective second-order differential voltage with a second-order comparison threshold, to determine a respective comparison result; and generate a respective second-order event signal based on the respective comparison result; and send the respective second-order event signal to a peripheral circuit; and the peripheral circuit, configured to, for each received second-order event signal, generate an address event representation based on the respective second-order event signal, wherein each address event representation comprises the respective second-order event signal and position information of the sensor that generated the respective second-order event signal. ### Claim 11 (depends on 10) A camera, comprising: the apparatus according to claim 10; and an operating circuit, configured to, for each address event representation, generate an image based on the respective address event representation. ### Claim 12 (depends on 11) A mobile terminal device, comprising: the camera according to claim 11; and a transmitter, configured to send each generated image to another device. ### Claim 13 (depends on 10) A system, comprising: the apparatus according to claim 10, and an operating circuit, configured to, for each address event representation, perform scene recognition based on the respective address event representation. ### Claim 14 A method, comprising: converting an optical signal into an electrical signal, to generate a photovoltage; performing second-order differential processing on the photovoltage, to generate a second-order differential voltage; and comparing the second-order differential voltage with a second-order comparison threshold to determine a comparison result, and generating a second-order event signal based on the comparison result. ### Claim 15 (depends on 14) The method according to claim 14, wherein the second-order differential voltage comprises a non-zero second-order differential voltage or a zero second-order differential voltage; and wherein performing second-order difference on the photovoltage, to generate the second-order differential voltage, comprises: when a change speed of a photovoltage at a current moment is different from a change speed of a photovoltage at a previous moment, generating the non-zero second-order differential voltage; or when the change speed of the photovoltage at the current moment is the same as the change speed of the photovoltage at the previous moment, generating the zero second-order differential voltage. ### Claim 16 (depends on 14) The method according to claim 14, wherein performing second-order differential processing on the photovoltage comprises: performing first-order differential processing on the photovoltage, to generate a first-order differential voltage; and performing first-order differential on the first-order differential voltage, to generate the second-order differential voltage. ### Claim 17 (depends on 16) The method according to claim 16, further comprising: comparing the first-order differential voltage with a first-order comparison threshold to generate a second comparison result, and generating a first-order event signal based on the second comparison result. ### Claim 18 (depends on 14) The method according to claim 14, further comprising: performing integration on the photovoltage, to generate an integral voltage signal.