Imaging device
An imaging device includes pixel units, a control unit, and a correction unit. The control unit causes each pixel unit to output first and second signal. The first signal is a potential of a floating diffusion held when the charge accumulated in a photoelectric conversion unit is transferred upon a transfer switch being closed. The second signal is a potential of the floating diffusion held when a reset switch is closed with the transfer switch being open. The correction unit generates, with respect to the first and second signals output by each pixel unit, the pixel signal by subtracting a correction amount from a signal intensity of the first signal. The correction amount is a product of a signal intensity of the second signal and a coefficient determined in advance in accordance with a position of each pixel unit.
1. An imaging device comprising:
a plurality of pixel units;
a control unit configured to control a signal output by each of the plurality of pixel units; and
a correction unit configured to correct the signal output by each of the plurality of pixel units to generate a pixel signal, wherein
each of the plurality of pixel units includes
a photoelectric conversion unit,
a transfer switch configured to transfer a charge generated in the photoelectric conversion unit to a floating diffusion, and
a reset switch configured to discharge the charge accumulated in the floating diffusion,
the control unit is configured to cause each of the plurality of pixel units to output a first signal and a second signal, the first signal being a potential of the floating diffusion held when the charge accumulated in the photoelectric conversion unit is transferred upon the transfer switch being closed, the second signal being a potential of the floating diffusion held when the reset switch is closed with the transfer switch being open, and
the correction unit is configured to generate, with respect to the first signal and the second signal output by each of the plurality of pixel units, the pixel signal by subtracting a correction amount from a signal intensity of the first signal, the correction amount being a product of a signal intensity of the second signal and a coefficient determined in advance in accordance with a position of each of the plurality of pixel units.
2. The imaging device according to claim 1 , wherein the correction unit is configured to generate the pixel signal by subtracting a correction amount from the signal intensity of the first signal when an analog gain set for an output of the first signal and an output of the second signal is smaller than a predetermined threshold, the correction amount being a product of the signal intensity of the second signal and a common coefficient determined in advance for the plurality of pixel units.
3. The imaging device according to claim 1 , further comprising a detection unit configured to detect a temperature in a vicinity of the plurality of pixel units, wherein
the correction unit is configured to calculate the correction amount with the use of the coefficient corresponding to a detection result of the detection unit.
4. The imaging device according to claim 1 , wherein the correction unit is configured to calculate the correction amount with the use of the coefficient set for a group of pixels grouped by an output signal line shared thereby.
5. The imaging device according to claim 1 , wherein the control unit is configured to cause the second signal to be output while the photoelectric conversion unit is accumulating the charge with the transfer switch being open.
6. The imaging device according to claim 1 , wherein the control unit is configured to, when the first signal is to be output alternatingly in different charge accumulation periods, cause the second signal to be output in a non-charge accumulation period provided between a first charge accumulation period and a second charge accumulation period that is shorter than the first charge accumulation period.