Radiation detector, method of driving the radiation detector, and radiation-image pickup system

A radiation detector comprising:

• a plurality of pixels disposed in a pixel area and including a first pixel and a second pixel disposed in a same column, the plurality of pixels being disposed in a matrix and each of the plurality of pixels including a conversion portion configured to directly convert radiation to electric charge and a transistor;
• a first comparator connected with the first pixel via a first vertical signal line;
• and
• a second comparator connected with the second pixel via a second vertical signal line,
• wherein a first distance from the transistor of the first pixel to the first vertical signal line is different from a second distance from the transistor of the second pixel to the second vertical signal line,
• wherein the first comparator is configured to receive a first reference signal and compare the first reference signal with an output signal sent from the first pixel to the first comparator via the first vertical signal line,
• wherein the second comparator is configured to receive a second reference signal and compare the second reference signal with an output signal sent from the second pixel to the second comparator via the second vertical signal line, the second reference signal being different from the first reference signal, and
• wherein the radiation detector is configured to output a comparison result from each of the first comparator and the second comparator.

A radiation detector comprising:

• a plurality of pixels disposed in a pixel area and including a first pixel and a second pixel disposed in a same column, the plurality of pixels being disposed in a matrix and each of the plurality of pixels including a conversion portion configured to directly convert radiation to electric charge and a transistor;
• a first comparator connected with the first pixel via a first vertical signal line;
• and
• a second comparator connected with the second pixel via a second vertical signal line,
• wherein a distance from the pixel area to the first comparator in the first vertical signal line is different from a distance from the pixel area to the second comparator in the second vertical signal line,
• wherein the first comparator is configured to receive a constant-voltage signal as a first reference signal and compare the first reference signal with an output signal sent from the first pixel to the first comparator via the first vertical signal line,
• wherein the second comparator is configured to receive a constant-voltage signal as a second reference signal and compare the second reference signal with an output signal sent from the second pixel to the second comparator via the second vertical signal line, voltage of the second reference signal being different from voltage of the first reference signal, and
• wherein the radiation detector is configured to output a comparison result from each of the first comparator and the second comparator.