Imaging device, method of converting read-out signal, and camera

A method of converting a read-out signal, the method comprising the steps of:

• reading out a read-out signal from a pixel unit for a first period;
• correcting the voltage of the read-out signal, which is read out in the reading out of a signal, for the first period to be constant;
• stopping the correcting of the voltage of the read-out signal;
• generating a clock signal having a frequency corresponding to the voltage of the read-out signal that is corrected in the stopping of the correcting of the voltage;
• counting the clock signals that are generated in the generating of a clock signal;
• correcting the frequency of the output clock signal, which is output in the counting of the clock signals, to a frequency that is higher than the frequency of the output clock signal;
• counting the output clock signals that are corrected in the correcting of the frequency of the output clock signal;
• reading out a read-out signal from the pixel unit for the second period;
• generating a clock signal having a frequency corresponding to the voltage of the read-out signal that is read out in the reading out of a signal for the second period;
• counting the clock signals generated in the generating of the clock signal;
• correcting the frequency of the output clock signal, which is output in the counting of the clock signals, to a frequency higher than the frequency of the output clock signal;
• and
• counting the output clock signals that are corrected in the correcting of the frequency of the output clock signal,
• wherein the clock signals are counted by a base 2M counter, and the output clock signals are counted by a base 2(N-M)/2 counter, M denoting the number of bits considered to be on the least significant bit side of the read-out signal, and N−M denoting the number of bits considered to be on the most significant bit side of the read-out signal.

A camera comprising:

• an imaging device;
• an optical system that guides light incident to a pixel area of the imaging device;
• and
• a signal processing unit that processes an output signal output by the imaging device,
• wherein the imaging device includes
• a pixel unit that converts incident light into an electrical signal corresponding to the amount of the incident light, and
• a read-out unit that reads out a read-out signal from the pixel unit for a first period and a second period,
• wherein the read-out unit includes
• a clock signal generating section that generates clock signals having a frequency corresponding to the voltage of the read-out signal,
• a first counter section that counts the clock signals generated by the clock signal generating section,
• a second counter section that counts output clock signals of the first counter section,
• a first correction section that corrects the voltage of the read-out signal to be constant before start of counting of the first and second counter sections for the first period and stops correction of the voltage of the read-out signal after the start of counting of the first and second counting sections for the first period and during the second period, and
• a second correction section that corrects a frequency of the output clock signals of the first counter section to a frequency that is higher than the frequency of the output clock signals,
• wherein the clock signals are counted by a base 2M counter, and the output clock signals are counted by a base 2(N-M)/2 counter, M denoting the number of bits considered to be on the least significant bit side of the read-out signal, and N−M denoting the number of bits considered to be on the most significant bit side of the read-out signal.