Solid state imaging device, imaging system, and drive method of solid state imaging device

A solid state imaging device comprising:

• a pixel comprising at least one photoelectric conversion unit and a transfer transistor connected to the photoelectric conversion unit;
• a reference signal generation unit that generates at least one reference signal that changes with the lapse of time at a predetermined change rate;
• and
• an analog-to-digital converter unit that includes a comparator unit configured to perform a comparison of the signal based on the pixel signal with the reference signal, and converts the pixel signal into a digital signal based on the comparison,
• wherein, in a first period, the analog-to-digital converter unit converts a first pixel signal into a first digital signal,
• in a determination period after the first period, the analog-to-digital converter unit performs the comparison of a second pixel signal with the reference signal set to a predetermined threshold,
• in a second period after the determination period, the analog-to-digital converter unit converts the second pixel signal at a gain in accordance with a result of the comparison performed in the determination period into a second digital signal,
• until the reference signal reaches the threshold from the first period, the reference signal generation unit changes the reference signal at the change rate that is larger than the change rate in the first period without changing a direction of change of the reference signal with respect to the lapse of time,
• change of voltage of the reference signal with respect to the lapse of time is continued without being interrupted until the reference signal reaches the threshold after the reference signal starts to change in the first period, and
• the direction of the change of the reference signal with respect to the lapse of time is not changed until the end of the determination period from the start of the first period.

A drive method of a solid state imaging device having a pixel that comprises a photoelectric conversion unit and a transfer transistor connected to the photoelectric conversion unit, and outputs a pixel signal corresponding to an incident light, a reference signal generation unit that generates a reference signal that changes with the lapse of time at a predetermined change rate, an amplifier unit that outputs, as a signal based on the pixel signal, a signal obtained by the pixel signal being amplified at a predetermined gain, and an analog-to-digital converter unit that includes a comparator unit configured to perform a comparison of the signal based on the pixel signal output by the amplifier unit with the reference signal, and converts the signal based on the pixel signal into a digital signal based on the comparison, the drive method comprising:

• in a first period, converting a signal output by the amplifier unit in which reset has been released into a first digital signal;
• in a determination period, performing the comparison of the signal based on the pixel signal with the reference signal set to a predetermined threshold;
• in a second period after the determination period, the amplifier unit amplifying the signal based on the pixel signal at a gain in accordance with a result of the comparison performed in the determination period;
• until the reference signal reaches the threshold from the first period, changing the reference signal without changing a direction of change of the reference signal with respect to the lapse of time;
• change of voltage of the reference signal with respect to the lapse of time is continued without being interrupted until the reference signal reaches the threshold after the reference signal starts to change in the first period, and
• the direction of the change of the reference signal with respect to the lapse of time is not changed until the end of the determination period from the start of the first period.

A solid state imaging device comprising:

• a pixel comprising at least one photoelectric conversion unit and a transfer transistor connected to the photoelectric conversion unit, and outputs a pixel signal corresponding to an incident light;
• a reference signal generation unit that generates at least one reference signal that changes with the lapse of time at a predetermined change rate;
• and
• an analog-to-digital converter unit that includes a comparator unit configured to output a result of a comparison of the pixel signal with the reference signal,
• wherein, in a first period, the analog-to-digital converter unit converts a first pixel signal into a first digital signal,
• in a determination period after the first period, the analog-to-digital converter unit performs the comparison of a second pixel signal with the reference signal set to a predetermined threshold,
• in a second period after the determination period, the analog-to-digital converter unit converts the second pixel signal at a gain in accordance with a result of the comparison performed in the determination period into a second digital signal,
• change of voltage of the reference signal with respect to the lapse of time is continued without being interrupted until the reference signal reaches the threshold after the reference signal starts to change when the comparator unit outputs the result of a comparison of the first pixel signal with the reference signal in the first period, and
• the direction of the change of the reference signal with respect to the lapse of time is not changed until the end of the determination period from the start of the first period.