# US 11,029,200 B2 · Ambient luminosity level detection > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,029,200 B2 - Document ID: US11029200B2 - Status: Granted - Kind: B2 - Application number: 15/890,533 - Filed: 2018-02-07 - Published: 2018-06-14 - Granted: 2021-06-08 - Earliest claimed: 2012-10-25 - Assignees: STMicroelectronics (Grenoble 2) SAS - Applicants: STMicroelectronics (Grenoble 2) SAS - Inventors: Pascal Mellot - Web page: https://patentgrep.com/patent/US11029200B2 ## CPC - G01J 1/4204: {with determination of ambient light (solar light G01J2001/4266)} - G01J 1/18: using comparison with a reference electric value - G01J 1/42: using electric radiation detectors (optical or mechanical part G01J1/04; by comparison with a reference light or electric value G01J1/10) - G01J 1/44: Electric circuits {(for command of an exposure part G03B7/02)} - G01J 2001/4426: {with intensity to frequency or voltage to frequency conversion [IFC or VFC]} - H04N 1/00917: {Resuming after an intentional interruption, e.g. resetting parameters} - 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) - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract The following steps are performed in connection with a photodiode circuit: a) resetting the photodiode circuit; b) determining when a photodiode voltage changes in response to illumination to reach a threshold; and c) updating a counter in response to the determination in step b). The steps a) to c) are repeated until an end of a measurement period is reached. The value of the counter at the end of the measurement period is then output to indicate an intensity of the illumination. ## Claims ### Claim 1 A method, comprising: a) resetting a photodiode; b) determining when a photodiode voltage changes in response to illumination to reach a threshold; c) updating a counter in response to the determination in step b); d) repeating steps a) to c) until an end of a measurement period is reached; and e) outputting a value of the counter at the end of the measurement period that is indicative of an intensity of said illumination; wherein a difference between a time for resetting the photodiode and a time when the threshold is reached is a discharge time; and wherein the measurement period expires when a sum of a plurality of consecutive discharge times equals or exceeds a threshold period. ### Claim 2 (depends on 1) The method of claim 1, wherein said measurement period is at least equal to a multiple of a half period of an A.C. mains power supply. ### Claim 3 (depends on 2) The method of claim 2, wherein the A.C. mains power supply operates at a frequency selected from a group consisting of 50 Hz and 60 Hz. ### Claim 4 (depends on 1) The method of claim 1, wherein said measurement period is selected according to a frequency of A.C. signals provided by an electric power supply network. ### Claim 5 (depends on 1) The method of claim 1, wherein said measurement period is a multiple of 50 ms. ### Claim 6 (depends on 1) The method of claim 1, further comprising measuring a charge level of the photodiode at the end of said measurement period. ### Claim 7 (depends on 6) The method of claim 6, further comprising adjusting the output value of the counter in response to the measured charge level. ### Claim 8 A method, comprising: a) sensing a discharge of a photodiode; b) in response to said sensing: triggering an updating of a counter storing a count value and resetting the photodiode; c) measuring a discharge time of the photodiode after resetting of the photodiode; d) repeating steps a) to c) over a time interval; and e) outputting a light intensity received by the photodiode as said count value of the counter at an end of the time interval; wherein the time interval is equal to a sum of a plurality of discharge times for said photodiode. ### Claim 9 (depends on 8) The method of claim 8, further comprising summing the plurality of discharge times; comparing the sum to a threshold duration; and terminating the time interval when the sum equals or exceeds the threshold duration. ### Claim 10 (depends on 9) The method of claim 9, wherein the threshold duration is selected according to a frequency of A.C. signals provided by an electric power supply network. ### Claim 11 (depends on 9) The method of claim 9, wherein said threshold duration is a multiple of 50 ms. ### Claim 12 (depends on 8) The method of claim 8, further comprising measuring a charge level of the photodiode at the end of said time interval. ### Claim 13 (depends on 12) The method of claim 12, further comprising adjusting the count value in response to the measured charge level. ### Claim 14 A method, comprising: a) generating by a photodiode of a voltage which changes at a rate dependent on illumination; b) comparing the voltage to a reference; c) incrementing a count value in response to said comparison and resetting the photodiode; repeating steps a) to c) until a measurement period expires; and outputting the count value at an end of the measurement period as being indicative of an intensity of said illumination; wherein a difference between a time for resetting the photodiode and a time for the compared voltage to pass the reference change is a discharge time, and wherein the measurement period expires when a sum of a plurality of consecutive discharge times equals or exceeds a threshold period. ### Claim 15 (depends on 14) The method of claim 14, wherein said measurement period is at least equal to a multiple of a half period of an A.C. mains power supply. ### Claim 16 (depends on 15) The method of claim 15, wherein the A.C. mains power supply operates at a frequency selected from the group consisting of 50 Hz and 60 Hz. ### Claim 17 (depends on 14) The method of claim 14, further comprising measuring the voltage of the photodiode at the end of said measurement period. ### Claim 18 (depends on 17) The method of claim 17, further comprising adjusting the count value in response to the measured voltage.