# US 2017/0257580 A1 · Imaging systems with flicker mitigation and high dynamic range > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0257580 A1 - Document ID: US20170257580A1 - Status: Published application - Kind: A1 - Application number: 15/597,326 - Filed: 2017-05-17 - Published: 2017-09-07 - Earliest claimed: 2015-09-30 - Assignees: Semiconductor Components Industries, LLC - Applicants: Semiconductor Components Industries, LLC - Inventors: Sandor BARNA - Web page: https://patentgrep.com/patent/US20170257580A1 ## CPC - H04N 25/589: with different integration times, e.g. short and long exposures - H04N 23/684: {performed by controlling the image sensor readout, e.g. by controlling the integration time} - H04N 23/73: by influencing the exposure time - H04N 23/741: by increasing the dynamic range of the image compared to the dynamic range of the electronic image sensors - H04N 23/745: Detection of flicker frequency or suppression of flicker wherein the flicker is caused by illumination, e.g. due to fluorescent tube illumination or pulsed LED illumination - H04N 25/616: involving a correlated sampling function, e.g. correlated double sampling [CDS] or triple sampling - H04N 25/65: applied to reset noise, e.g. KTC noise related to CMOS structures by techniques other than CDS - H04N 25/713: Transfer or readout registers; Split readout registers or multiple readout registers - H04N 25/77: Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components - H04N 25/78: Readout circuits for addressed sensors, e.g. output amplifiers or A/D converters - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract An image pixel may include a shutter element that is operable in an open state during which a corresponding photodiode accumulates charge and a closed state during which charge is drained from the photodiode. During a first portion of an image frame, the image pixel may operate in a flicker mitigation mode in which a non-continuous exposure period is used. During a second portion of the image frame, the image pixel may operate in a high dynamic range mode in which images are obtained with exposures of varying lengths. To conserve memory requirements, the signal from the flicker mitigation mode may not be sampled until the end of the first exposure of the high dynamic range mode. ## Claims ### Claim 1 A method for capturing image data for an image pixel during an image frame, wherein the image pixel comprises a photodiode, a charge storage region, a transfer transistor coupled between the charge storage region and the photodiode, and a charge readout circuit coupled between the charge storage region and an output line, the method comprising: during a first time period, accumulating charge during a first exposure period, wherein the charge accumulated during the first exposure period is transferred to the charge storage region with the transfer transistor; during a second time period subsequent to the first time period, accumulating charge during a second exposure period; and after the majority of the second time period has passed, supplying a first signal to the output line corresponding to the charge accumulated during the first exposure period. ### Claim 2 (depends on 1) The method defined in claim 1, wherein the image pixel further comprises a reset transistor, the method further comprising: after supplying the first signal to the output line corresponding to the charge accumulated during the first exposure period, resetting the charge storage region with the reset transistor. ### Claim 3 (depends on 2) The method defined in claim 2, further comprising: after resetting the charge storage region with the reset transistor, supplying a second signal to the output line corresponding to a reset level of charge. ### Claim 4 (depends on 3) The method defined in claim 3, further comprising: after supplying the second signal to the output line corresponding to the reset level of charge, transferring the charge accumulated during the second exposure period to the charge storage region. ### Claim 5 (depends on 4) The method defined in claim 4, further comprising: after transferring the charge accumulated during the second exposure period to the charge storage region, supplying a third signal to the output line corresponding to the charge accumulated during the second exposure period. ### Claim 6 (depends on 5) The method defined in claim 5, wherein transferring charge accumulated during the second exposure period to the charge storage region comprises transferring charge accumulated during the second exposure period to the charge storage region during the second time period and wherein supplying the third signal to the output line corresponding to the charge accumulated during the second exposure period comprises supplying the third signal to the output line corresponding to the charge accumulated during the second exposure period during a third time period that is subsequent to the second time period. ### Claim 7 (depends on 6) The method defined in claim 6, further comprising: during the third time period, accumulating charge during a third exposure period, wherein the third exposure period is shorter than the second exposure period. ### Claim 8 (depends on 1) The method defined in claim 1, wherein the second time period immediately follows the first time period. ### Claim 9 A method for capturing image data for an image pixel during an image frame, wherein the image pixel comprises a photodiode, a charge storage region, and a charge readout circuit coupled between the charge storage region and an output line, the method comprising: with the photodiode, accumulating an amount of charge for a first time period, wherein the amount of charge is stored in the charge storage region; with the photodiode, accumulating an additional amount of charge for a second time period that is subsequent to the first time period; and at the end of second time period, using the charge readout circuit to supply a first signal to the output line corresponding to the amount of charge on the charge storage region. ### Claim 10 (depends on 9) The method defined in claim 9, further comprising: after using the charge readout circuit to supply the first signal to the output line corresponding to the amount of charge on the charge storage region, resetting the amount of charge at the charge storage region with a reset transistor. ### Claim 11 (depends on 10) The method defined in claim 10, further comprising: after resetting the amount of charge at the charge storage region with the reset transistor, supplying a second signal to the output line corresponding to the amount of charge on the charge storage region. ### Claim 12 (depends on 11) The method defined in claim 11, further comprising: using the second signal to correct for reset noise in the first signal. ### Claim 13 (depends on 11) The method defined in claim 11, further comprising: after supplying the second signal to the output line corresponding to the amount of charge on the charge storage region, transferring the additional amount of charge that accumulated during the second time period to the charge storage region with a transfer transistor. ### Claim 14 (depends on 13) The method defined in claim 13, further comprising: after transferring the additional amount of charge that accumulated during the second time period to the charge storage region, supplying a third signal to the output line corresponding to the additional amount of charge that accumulated during the second time period. ### Claim 15 (depends on 9) The method defined in claim 9, wherein the second time period immediately follows the first time period. ### Claim 16 A method for capturing image data for an image pixel during an image frame, wherein the image pixel comprises a photodiode, a charge storage region, a transfer transistor coupled between the charge storage region and the photodiode, a reset transistor, and a charge readout circuit coupled between the charge storage region and an output line, the method comprising: during a first time period, accumulating charge in the photodiode during a first exposure period; transferring the charge accumulated during the first exposure period to the charge storage region using the transfer transistor; supplying a first signal to the output line corresponding to the charge accumulated during the first exposure period; after supplying the first signal to the output line corresponding to the charge accumulated during the first exposure period, resetting the charge storage region with the reset transistor; and after resetting the charge storage region with the reset transistor, supplying a second signal to the output line corresponding to a reset level of charge. ### Claim 17 (depends on 16) The method defined in claim 16, further comprising: using the second signal to correct for reset noise in the first signal. ### Claim 18 (depends on 16) The method defined in claim 16, wherein supplying the first signal to the output line comprises supplying the first signal to the output line during a second exposure period and wherein an additional amount of charge is accumulated in the photodiode during the second exposure period. ### Claim 19 (depends on 18) The method defined in claim 18, wherein supplying the first signal to the output line comprises supplying the first signal to the output line after the majority of the second exposure period has passed. ### Claim 20 (depends on 19) The method defined in claim 19, wherein the second exposure period immediately follows the first exposure period.