IMAGE SENSOR, CAMERA, SURVEILLANCE SYSTEM, AND METHOD FOR DRIVING THE IMAGE SENSOR
First Claim
1. An image sensor comprising:
- a vertical signal line;
a pixel electrically connected to the vertical signal line; and
an analog-digital conversion device electrically connected to the vertical signal line,wherein the pixel includes a photodiode, a first capacitor, a first transistor, a second transistor, a third transistor, a first wiring, a second wiring, a third wiring, and a fourth wiring,wherein one electrode of the first capacitor is electrically connected to an anode of the photodiode,wherein the other electrode of the first capacitor is electrically connected to a gate of the second transistor,wherein a node between the other electrode of the first capacitor and the gate of the second transistor is configured to store a potential corresponding to an amount of electric charge generated in the photodiode,wherein a gate of the first transistor is electrically connected to the first wiring,wherein one of a source and a drain of the first transistor is electrically connected to the node, and the other of the source and the drain of the first transistor is electrically connected to the third wiring,wherein one of a source and a drain of the second transistor is electrically connected to one of a source and a drain of the third transistor,wherein a gate of the third transistor is electrically connected to the second wiring,wherein the analog-digital conversion device includes a comparator to which a first or second reference potential is input and which compares the first or second reference potential with an analog signal input through the vertical signal line; and
a counter which measures a period during which comparison operation is performed by the comparator and holds a measurement result thereof as a digital value,wherein, the counter is configured to hold an N-bit digital value (N is an integer of 3 or more) as the measurement result when the comparator performs comparison operation using the first reference potential, andwherein the counter is configured to hold an M-bit digital value (M is an integer of 2 or more and less than N) as the measurement result when the comparator performs comparison operation using the second reference potential.
1 Assignment
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Accused Products
Abstract
Provided is an image sensor having a pixel includes a photoelectric conversion element; a capacitor which is connected between the photoelectric conversion element; a reset circuit which resets a potential of a node between the photoelectric conversion element and the capacitor; an amplifier circuit which outputs a signal corresponding to the potential of the node; and a switch which controls electrical conduction between the amplifier circuit and a vertical signal line. When the node is brought into an electrically floating state, the potential of the optical signal is stored in the node in a state of being inverted. When an optical signal is detected while the potential is stored in the node, the potential of the node increases in accordance with an output potential of the photoelectric conversion element, and thus the potential of the node corresponds to a difference in potential between the optical signals in different light-receiving periods.
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Citations
19 Claims
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1. An image sensor comprising:
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a vertical signal line; a pixel electrically connected to the vertical signal line; and an analog-digital conversion device electrically connected to the vertical signal line, wherein the pixel includes a photodiode, a first capacitor, a first transistor, a second transistor, a third transistor, a first wiring, a second wiring, a third wiring, and a fourth wiring, wherein one electrode of the first capacitor is electrically connected to an anode of the photodiode, wherein the other electrode of the first capacitor is electrically connected to a gate of the second transistor, wherein a node between the other electrode of the first capacitor and the gate of the second transistor is configured to store a potential corresponding to an amount of electric charge generated in the photodiode, wherein a gate of the first transistor is electrically connected to the first wiring, wherein one of a source and a drain of the first transistor is electrically connected to the node, and the other of the source and the drain of the first transistor is electrically connected to the third wiring, wherein one of a source and a drain of the second transistor is electrically connected to one of a source and a drain of the third transistor, wherein a gate of the third transistor is electrically connected to the second wiring, wherein the analog-digital conversion device includes a comparator to which a first or second reference potential is input and which compares the first or second reference potential with an analog signal input through the vertical signal line; and
a counter which measures a period during which comparison operation is performed by the comparator and holds a measurement result thereof as a digital value,wherein, the counter is configured to hold an N-bit digital value (N is an integer of 3 or more) as the measurement result when the comparator performs comparison operation using the first reference potential, and wherein the counter is configured to hold an M-bit digital value (M is an integer of 2 or more and less than N) as the measurement result when the comparator performs comparison operation using the second reference potential. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method for driving an image sensor:
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the image sensor including; a pixel, a vertical signal line and a signal processing circuit which is configured to convert an analog signal output from the pixel through the vertical signal line into a digital signal, wherein the pixel includes a capacitor;
a photoelectric conversion element electrically connected to one electrode of the capacitor;
an amplifier circuit electrically connected to the other electrode of the capacitor, the amplifier circuit configured to output an analog signal corresponding to a potential of a node between the other electrode of the capacitor and the amplifier circuit;
a first switch which controls electrical conduction between the amplifier circuit and the vertical signal line; and
a circuit which resets the potential of the node;the method for driving the image sensor comprising; a first step of accumulating electric charge in the photoelectric conversion element while the node is an electrically floating state; a second step of reading the analog signal corresponding to the potential of the node in the first step through the vertical signal line and converting the analog signal into an N-bit digital signal (N is an integer of 3 or more) in the signal processing circuit; a third step of accumulating electric charge in the photoelectric conversion element while the potential of the node is fixed, and then bringing the node into an electrically floating state; a fourth step, after the third step, of accumulating electric charge in the photoelectric conversion element while the node is maintained in an electrically floating state; and a fifth step of reading the analog signal corresponding to the potential of the node in the fourth step through the vertical signal line and converting the analog signal into an M-bit digital signal (M is an integer of 2 or more and less than N) in the signal processing circuit. - View Dependent Claims (17)
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18. A method for driving an image sensor:
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the image sensor including; a pixel, a vertical signal line and a signal processing circuit which is configured to convert an analog signal output from the pixel through the vertical signal line into a digital signal, wherein the pixel includes a capacitor;
a photoelectric conversion element electrically connected to one electrode of the capacitor;
an amplifier circuit electrically connected to the other electrode of the capacitor, the amplifier circuit configured to output an analog signal corresponding to a potential of a node between the other electrode of the capacitor and the amplifier circuit;
a first switch which controls electrical conduction between the amplifier circuit and the vertical signal line;
a circuit which resets the potential of the node by supplying a constant potential to the node; and
a second switch which controls electrical conduction between the photoelectric conversion element and the other electrode of the capacitor;the method for driving the image sensor comprising; a first step of accumulating electric charge in the photoelectric conversion element in a state where the second switch is turned on and then turning off the second switch, while the node is maintained in an electrically floating state; a second step of reading the analog signal corresponding to the potential of the node in the first step through the vertical signal line and converting the analog signal into an N-bit digital signal (N is an integer of 3 or more) in the signal processing circuit; a third step of accumulating electric charge in the photoelectric conversion element in the state where the second switch is turned on and then turning off the second switch while the potential of the node is fixed, and then bringing the node into an electrically floating state; a fourth step, after the third step, of accumulating electric charge in the photoelectric conversion element in the state where the second switch is turned on and then turning off the second switch while the node is maintained in an electrically floating state; and a fifth step of reading the analog signal corresponding to the potential of the node in the fourth step through the vertical signal line and converting the analog signal into an M-bit digital signal (M is an integer of 2 or more and less than N) in the signal processing circuit. - View Dependent Claims (19)
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Specification