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US 2017/0318248 A1Published application
Image capturing apparatus and image capturing system
AssigneeCanon Kabushiki Kaisha
InventorYu Maehashi
Life of this patent
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Abstract
An image capturing apparatus includes a comparison circuit unit including a first comparator and a second comparator. The second comparator is kept in a non-operating state until the signal level of a first comparison result signal from the first comparator changes and is brought into an operating state in correspondence with a change in the signal level of the first comparison result signal.
Claims20
An image capturing apparatus comprising:
- a pixel outputting a pixel signal;
- a ramp-signal supplying unit configured to output a ramp signal whose potential changes with a lapse of time;
- and
- an analog-to-digital conversion unit,
- wherein the analog-to-digital conversion unit comprises:
- an offset imparting unit configured to impart an offset to at least one of the pixel signal and the ramp signal;
- a first comparator configured to perform first comparison that is comparison between the pixel signal and the ramp signal, at least one of the pixel signal and the ramp signal being offset by the offset imparting unit, and to output a first comparison result signal indicating a result of the first comparison;
- and
- a second comparator configured to perform second comparison that is comparison between the pixel signal and the ramp signal and to output a second comparison result signal indicating a result of the second comparison,
- wherein, in the analog-to-digital conversion unit, the first comparison result signal and the second comparison result signal change in signal level in that order due to the offset during an analog-to-digital conversion period from start of a change in potential of the ramp signal to end of the change,
- wherein the second comparator is in a non-operating state during a period from start of the analog-to-digital conversion period until the signal level of the first comparison result signal changes,
- wherein the second comparator enters an operating state in correspondence with a change in the signal level of the first comparison result signal to perform the second comparison, and
- wherein current consumption per unit time of the first comparison is lower than current consumption per unit time of the second comparison.
10 more elements
An image capturing system comprising:
- an image capturing apparatus;
- and
- a signal processing unit configured to generate an image by processing a signal output from the image capturing apparatus,
- wherein the image capturing apparatus comprises:
- a pixel outputting a pixel signal;
- a ramp-signal supplying unit configured to output a ramp signal whose potential changes with the lapse of time;
- and
- an analog-to-digital conversion unit,
- wherein the analog-to-digital conversion units comprises:
- an offset imparting unit configured to impart an offset to at least one of the pixel signal and the ramp signal;
- a first comparator configured to perform first comparison that is comparison between the pixel signal and the ramp signal, at least one of the pixel signal and the ramp signal being offset by the offset imparting unit, and to output a first comparison result signal indicating a result of the first comparison;
- and
- a second comparator configured to perform second comparison that is comparison between the pixel signal and the ramp signal and to output a second comparison result signal indicating a result of the second comparison,
- wherein, in the analog-to-digital conversion unit, the first comparison result signal and the second comparison result signal change in signal level in that order due to the offset during an analog-to-digital conversion period from start of a change in potential of the ramp signal to end of the change,
- wherein the second comparator is in a non-operating state during a period from start of the analog-to-digital conversion period until the signal level of the first comparison result signal changes,
- wherein the second comparator enters an operating state in correspondence with a change in the signal level of the first comparison result signal to perform the second comparison, and
- wherein current consumption per unit time of the first comparison is lower than current consumption per unit time of the second comparison.
14 more elements
Dependencies are inferred from the claim text.