A radiation imaging apparatus including an accumulation unit to accumulate electrical charge in accordance with radiation for each pixel circuit of a plurality of pixel circuits. An output unit outputs an analog signal for each pixel circuit by sampling and holding an electrical signal in accordance with a voltage of an accumulation unit for each pixel circuit. The output unit stops the output during a reset operation of the accumulation unit. A selection unit selects pixel circuits that output the analog signals. The selection unit stops the selection during a reset operation of the accumulation unit. A determination unit determines whether a total time of an exposure time and an output time required to output the analog signals corresponding to all the pixel circuits is longer than an imaging interval that is based on a synchronization signal representing a radiation generation timing input from an external apparatus.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A radiation imaging apparatus comprising: an accumulation unit adapted to accumulate electrical charge in accordance with exposure to generated radiation in each pixel circuit of a plurality of pixel circuits; an output unit adapted to output an analog signal for each pixel circuit by sampling and holding an electrical signal in accordance with a voltage of an accumulation unit for each pixel circuit, wherein the output unit stops the output during a reset operation of the accumulation unit; a selection unit adapted to select pixel circuits that output the analog signals, wherein the selection unit stops the selection during a reset operation of the accumulation unit; a detection unit adapted to detect a synchronization signal representing a radiation generation timing; and a determination unit adapted to determine whether a total time of an exposure time and an output time required to output the analog signals corresponding to all of the pixel circuits is longer than an imaging interval that is based on the synchronization signal, wherein, when the determination unit determines that the total time is longer than the imaging interval, the selection unit stops the selection and the output unit stops the output, in accordance with the stoppage of the selection, after the output unit outputs the electrical signals corresponding to a predetermined number of pixel circuits as analog signals.
2. The apparatus according to claim 1 , further comprising a control unit adapted to control the output unit to sample and to hold the electrical signal after starting of the radiation generated, for exposure, at the imaging interval corresponding to the synchronization signal, and the exposure time elapses, wherein the radiation is irradiated to the accumulation unit in the form of pulses having the exposure time that is shorter than the imaging interval, and wherein the selection unit starts a sequential selection of the pixel circuits between the reset operation of the accumulation unit.
3. The apparatus according to claim 2 , wherein a photodiode and a capacitor of each of the pixel circuits are reset when the detection unit detects the synchronization signal again, the selection unit resumes the selection, and the output unit resumes the output at a position of a remaining pixel circuit, after a predetermined period of time elapses since a start of exposure of the radiation at the imaging interval corresponding to the synchronization signal, before the exposure time elapses.
4. The apparatus according to claim 3 , further comprising a correction unit adapted to correct a noise offset based on a difference between a radiation image, based on the analog signal output from the output unit and pixel value data of fixed pattern noise acquired by the output unit in advance, based on the analog signal output in advance, before the exposure of the radiation.
5. The apparatus according to claim 4 , wherein the selection unit selects a position of a pixel circuit, for each array of pixel circuits, which outputs the analog signal.
6. A control method for a radiation imaging apparatus, the control method comprising: an accumulation step of accumulating electrical charge into an accumulation unit in accordance with exposure to generated radiation in each pixel circuit of a plurality of pixel circuits; an output step of outputting an analog signal for each pixel circuit by sampling and holding an electrical signal in accordance with a voltage of an accumulation unit for each pixel circuit, wherein, in the output step, the output is stopped during a reset operation of the accumulation unit; a selection step of selecting pixel circuits that output the analog signals, wherein, in the selection step, the selection is stopped during a reset operation of the accumulation unit; a detection step of detecting a synchronization signal representing a radiation generation timing; and a determination step of determining whether a total time of an exposure time and an output time required to output the analog signals corresponding to all of the pixel circuits is longer than an imaging interval that is based on the synchronization signal, wherein, when the determination step determines that the total time is longer than the imaging interval, the selection is stopped in the selection step and the output is stopped in the output step, in accordance with the stoppage of the selection, after electrical signals are outputted in the output step corresponding to a predetermined number of pixel circuits.
7. A radiation imaging apparatus comprising: a plurality of pixel circuits, each of the plurality of pixel circuits comprising (i) a conversion unit adapted to convert generated radiation to a signal, (ii) a sampling and holding unit adapted to sample and to hold the signal, (iii) an output unit adapted to output the signal sampled and held by the sampling and holding unit, and (iv) a resetting unit adapted to reset the conversion unit; a selection unit adapted to perform a selection operation of a pixel circuit that is to output the sampled and held signal, in order to output the sampled and held signal from the plurality of pixel circuits; a control unit adapted to control the plurality of pixel circuits so that the reset is collectively performed to the plurality of pixel circuits, based on a signal indicative of radiation generation timing that is detected by the control unit, and the sampling and holding is collectively performed to the plurality of pixel circuits; and a determination unit adapted to determine whether or not the selection operation to the plurality of pixel circuits, based on an immediately preceding signal indicative of the timing is completed, when the reset is performed based on the signal indicative of the timing, wherein, if the determination unit determines that the selection operation is not completed, the selection unit stops the selection operation in which a portion of pixel circuits, out of the plurality of pixel circuits, remains unselected, and resumes the selection operation to the portion of the pixel circuits after the control unit performs the reset.
8. The apparatus according to claim 7 , wherein the radiation is irradiated to the plurality of pixel circuits in the form of pulses having an exposure time that is shorter than an imaging interval defined by an interval of two consecutive signals representing the timing, wherein the selection unit starts a selection operation of the pixel circuits between the reset operation of the resetting unit, and wherein the selection unit performs the selection operation to the portion of the pixel circuits after a predetermined time elapses from the reset having been performed by the control unit.
9. The apparatus according to claim 7 , wherein the selection unit performs the selection operation after a predetermined time elapses from the reset having been performed by the control unit.
10. The apparatus according to claim 7 , further comprising a correction unit adapted to obtain pixel value data of fixed-pattern noise based on a signal preliminarily outputted by the output unit before a radiation exposure, and to correct an offset of noise based on the difference between the obtained pixel value data and a radiation image that is based on a signal outputted by the output unit.
11. A computer-readable non-transitory storage medium storing a program for causing a computer to execute each step in a control method for a radiation imaging apparatus, the control method comprising: an accumulation step of accumulating electrical charge into an accumulation unit in accordance with exposure to generated radiation in each pixel circuit of a plurality of pixel circuits; an output step of outputting an analog signal for each pixel circuit by sampling and holding an electrical signal in accordance with a voltage of an accumulation unit for each pixel circuit, wherein, in the output step, the output is stopped during a reset operation of the accumulation unit; a selection step of selecting pixel circuits that output the analog signals, wherein, in the selection step, the selection is stopped during a reset operation of the accumulation unit; a detection step of detecting a synchronization signal representing a radiation generation timing; and a determination step of determining whether a total time of an exposure time and an output time required to output analog signals corresponding to all of the pixel circuits is longer than an imaging interval that is based on the synchronization signal, wherein, when the determination step determines that the total time is longer than the imaging interval, the selection is stopped in the selection step and the output is stopped in the output step, in accordance with the stoppage of the selection, after electrical signals are outputted in the output step corresponding to a predetermined number of pixel circuits.
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September 20, 2011
February 23, 2016
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