Solid-state image sensor and imaging device
In a solid-state image sensor that detects presence or absence of an address event, power consumption when capturing an image is reduced. The solid-state image sensor includes a plurality of pixels and an analog-digital conversion unit. In the solid-state image sensor, each of the plurality of pixels generates an analog signal by photoelectric conversion. Moreover, in the solid-state image sensor, the analog-digital conversion unit converts the analog signal of a pixel into a digital signal, the pixel having an amount of change in incident light amount that falls outside a predetermined range, of the plurality of pixels.
1. A solid-state image sensor comprising:
a plurality of pixels each configured to generate an analog signal by photoelectric conversion;
an analog-digital conversion unit configured to convert the analog signal into a digital signal for at least one of the pixels having an amount of change in an incident light amount that falls outside a predetermined range; and
a row arbiter configured to arbitrate first requests from a predetermined number of respective rows arrayed in a direction perpendicular to a predetermined direction, wherein
the plurality of pixels is arrayed in the predetermined number of rows, and
each of the plurality of pixels is configured to transmit one of the first requests in a case where the amount of change falls outside the predetermined range.
2. The solid-state image sensor according to claim 1 , wherein
the analog-digital conversion unit includes
selection circuitry configured to select the analog signal of the pixel having the amount of change that falls outside the predetermined range from among the analog signals of the plurality of pixels, and
an analog-digital converter that converts the selected analog signal into the digital signal.
3. The solid-state image sensor according to claim 1 , wherein
the plurality of pixels is provided in a predetermined number of columns arrayed in a predetermined direction,
the analog-digital conversion unit includes a fixed number of analog-digital converters for each of the columns, and
in a case where the amount of change of at least one of the pixels belonging to the corresponding column falls outside the predetermined range, the corresponding analog-digital converter converts the analog signal of the pixel into the digital signal.
4. The solid-state image sensor according to claim 1 , wherein
the plurality of pixels is provided in a predetermined number of columns arrayed in a predetermined direction, and
the analog-digital conversion unit includes
a first analog-digital conversion unit connected to part of the predetermined number of columns, and
a second analog-digital conversion unit connected to rest of the predetermined number of columns.
5. The solid-state image sensor according to claim 4 , wherein
each of the first and second analog-digital conversion units includes
selection circuitry configured to select the analog signal of a column having the amount of change that falls outside the predetermined range from among the analog signals of the corresponding columns, and
an analog-digital converter that converts the selected analog signal into the digital signal.
6. The solid-state image sensor according to claim 4 , wherein
each of the first and second analog-digital conversion units includes a fixed number of analog-digital converters for the respective corresponding columns, and
in a case where the amount of change of one of the pixels belonging to one of the respective corresponding columns falls outside the predetermined range, the analog-digital converter converts the analog signal of the pixel into the digital signal.
7. The solid-state image sensor according to claim 1 , wherein
each of the plurality of pixels includes
pixel signal generation circuitry configured to generate the analog signal, and
detection circuitry configured to detect whether or not an absolute value of the amount of change exceeds a predetermined threshold, and generates a predetermined enable signal on a basis of a detection result, and
the analog-digital conversion unit converts the analog signal into the digital signal according to the enable signal.
8. The solid-state image sensor according to claim 1 , further comprising:
a column arbiter configured to arbitrate second requests from a predetermined number of respective columns arrayed in the predetermined direction, wherein
each of the plurality of pixels is configured to transmits one of the second requests on a basis of an arbitration result of the row arbiter.
9. The solid-state image sensor according to claim 8 , wherein
the column arbiter generates a predetermined enable signal on a basis of the one of the second requests, and
the analog-digital conversion unit converts the analog signal into the digital signal according to the enable signal.
10. An imaging device comprising:
a plurality of pixels each configured to generate an analog signal by photoelectric conversion;
an analog-digital conversion unit configured to convert the analog signal of a pixel into a digital signal for at least one of the pixels having an absolute value of an incident light amount that falls outside a predetermined range; and
signal processing or configured to process the digital signal;
a row arbiter configured to arbitrate first requests from a predetermined number of respective rows arrayed in a direction perpendicular to a predetermined direction, wherein
the plurality of pixels is arrayed in the predetermined number of rows, and
each of the plurality of pixels is configured to transmit one of the first requests in a case where the absolute value falls outside the predetermined range.
11. The imaging device according to claim 10 , wherein
the analog-digital conversion unit includes
selection circuitry configured to select the analog signal of the pixel having the absolute value that falls outside the predetermined range from among the analog signals of the plurality of pixels, and
an analog-digital converter that converts the selected analog signal into the digital signal.
12. The imaging device according to claim 10 , wherein
the plurality of pixels is provided in a predetermined number of columns arrayed in a predetermined direction,
the analog-digital conversion unit includes a fixed number of analog-digital converters for each of the columns, and
in a case where the absolute value of at least one of the pixels belonging to the corresponding column falls outside the predetermined range, the corresponding analog-digital converter converts the analog signal of the pixel into the digital signal.
13. The imaging device according to claim 10 , wherein
the plurality of pixels is provided in a predetermined number of columns arrayed in a predetermined direction, and
the analog-digital conversion unit includes
a first analog-digital conversion unit connected to part of the predetermined number of columns, and
a second analog-digital conversion unit connected to rest of the predetermined number of columns.
14. The imaging device according to claim 13 , wherein
each of the first and second analog-digital conversion units includes
selection circuitry configured to select the analog signal of a column having the absolute value that falls outside the predetermined range from among the analog signals of the corresponding columns, and
an analog-digital converter that converts the selected analog signal into the digital signal.
15. The imaging device according to claim 13 , wherein
each of the first and second analog-digital conversion units includes a fixed number of analog-digital converters for the respective corresponding columns, and
in a case where the absolute value of one of the pixels belonging to one of the respective corresponding columns falls outside the predetermined range, the analog-digital converter converts the analog signal of the pixel into the digital signal.
16. The imaging device according to claim 10 , wherein
each of the plurality of pixels includes
pixel signal generation circuitry configured to generate the analog signal, and
detection circuitry configured to detect whether or not an absolute value of the absolute value exceeds a predetermined threshold, and generates a predetermined enable signal on a basis of a detection result, and
the analog-digital conversion unit converts the analog signal into the digital signal according to the enable signal.
17. The imaging device according to claim 10 , further comprising:
a column arbiter configured to arbitrate second requests from a predetermined number of respective columns arrayed in the predetermined direction, wherein
each of the plurality of pixels is configured to transmit one of the second requests on a basis of an arbitration result of the row arbiter.
18. The imaging device according to claim 17 , wherein
the column arbiter generates a predetermined enable signal on a basis of the one of the second requests, and
the analog-digital conversion unit converts the analog signal into the digital signal according to the enable signal.