Photoelectric conversion device and photoelectric conversion system

A photoelectric conversion device comprising:

• a pixel unit including
• a photoelectric conversion unit configured to output a pulse signal in response to incidence of light;
• a count unit including a counter configured to count the pulse signal output from the photoelectric conversion unit during a predetermined exposure period and a count value holding unit configured to hold a count value of the counter;
• a count control unit configured to control the count unit;
• and
• a determination unit configured to perform a determination processing of determining whether or not there is a change in an amount of light incident on the photoelectric conversion unit based on a count value of the counter,
• wherein the exposure period includes a plurality of periods including at least a first period and a second period,
• wherein the count control unit is configured to control the count unit to output a difference value between a first count value in the first period and a second count value in the second period,
• wherein the determination unit is configured to perform the determination processing based on the difference value,
• wherein the count control unit is configured to control the counter, when the difference value is equal to or less than a predetermined threshold value, to read out the first count value held by the count value holding unit to the counter and start a count operation in a third period of the exposure period from the first count value, and
• wherein the determination unit is configured to further perform the determination processing based on a difference value between the first count value and a third count value in the third period.