Image capturing apparatus, image capturing system, and equipment

1 . An image capturing apparatus comprising:

a pixel region having a plurality of pixels configured to generate and output event signals upon detecting a variation in quantity of incident light; and

a readout circuit configured to read out the event signals output from the pixel region,

wherein the readout circuit counts the number of the event signals read out from the pixel region, and when the number of the counted event signals exceeds a preset threshold within a predetermined period, the readout circuit discards the event signals read out from the pixel region, and transmits an acknowledge signal to the pixel region,

the pixel detects a new variation in the quantity of incident light in accordance with the acknowledge signal,

the pixel updates a setting for detection of a variation in the quantity of incident light in accordance with the acknowledge signal, and

the readout circuit further transmits the acknowledge signal to the pixel that has output the event signal upon reading out the event signal.

2 . The apparatus according to claim 1 , wherein the pixel detects a new variation in the quantity of incident light in accordance with the acknowledge signal.

3 . The apparatus according to claim 1 , wherein the pixel updates a setting for detection of a variation in the quantity of incident light in accordance with the acknowledge signal.

4 . The apparatus according to claim 1 , wherein the readout circuit further transmits the acknowledge signal to the pixel that has output the event signal upon reading out the event signal.

5 . The apparatus according to claim 1 , wherein the pixel comprises a light amount variation detector, the light amount variation detector comprising:

a photodiode configured to output a photocurrent corresponding to a quantity of incident light,

a current/voltage converter configured to convert the photocurrent into a signal potential,

a subtractor configured to output a potential corresponding to a difference between the signal potential and a reference potential, and

a comparator configured to compare an output from the subtractor with a threshold and output a signal when an output from the subtractor exceeds the threshold.

6 . The apparatus according to claim 5 , wherein the light amount variation detector updates the reference potential with the signal potential in accordance with the acknowledge signal.

7 . The apparatus according to claim 1 , wherein the readout circuit further comprises an arbiter configured to arbitrate, when the pixel region generates a plurality of the event signals in a predetermined period, a readout order of the event signals from among the plurality of event signals.

8 . The apparatus according to claim 6 , wherein the readout circuit further comprises an arbiter configured to arbitrate, when the pixel region generates a plurality of the event signals in a predetermined period, a readout order of the event signals from among the plurality of event signals.

9 . The apparatus according to claim 8 , wherein the arbiter further comprises a priority determination unit configured to hold priority corresponding to a readout order of the event signals and performs the arbitration based on the priority.

10 . The apparatus according to claim 1 , wherein the readout circuit further comprises an addressing unit configured to output an event signal read out from the pixel upon attaching an address corresponding to a position of the pixel to the event signal, and

the readout circuit counts how many of the event signals have a predetermined address attached there to, and when the number of the counted event signals exceeds a threshold, the readout circuit discards the event signals read out from the pixel region and transmits the acknowledge signal to the pixel region.

11 . The apparatus according to claim 1 , wherein a predetermined pixel of the pixels is a detection pixel, and

the readout circuit counts the event signals read out from the detection pixel, and when the number of the counted event signals exceeds a threshold, the readout circuit discards the event signals read out from the pixel region and transmits an acknowledge signal to the pixel region.

12 . The apparatus according to claim 11 , wherein the detection pixel comprises:

a photodiode configured to output a photocurrent corresponding to a quantity of incident light,

a current/voltage converter configured to convert the photocurrent into a signal potential,

a subtractor configured to output a potential corresponding to a difference between the signal potential and a reference potential, and

a comparator configured to compare an output from the subtractor with a threshold and output a signal when an output from the subtractor exceeds the threshold,

wherein the reference potential is updated with the signal potential when the acknowledge signal is received.

13 . The apparatus according to claim 1 , wherein a plurality of pixels are arranged in a matrix pattern in the pixel region, and the pixel circuit reads out event signals for each row from the pixel region.

14 . An image capturing system comprising:

an image capturing apparatus defined in claim 1 ; and

an arithmetic device configured to process a signal output from the image capturing apparatus.

15 . Equipment comprising:

an image capturing apparatus defined in claim 1 ; and

a processing apparatus configured to process a signal output from the image capturing apparatus.

16 . An image capturing apparatus comprising:

a pixel region having a plurality of pixels configured to generate and output event signals upon detecting a variation in quantity of incident light; and

a readout circuit configured to read out the event signals output from the pixel region,

wherein the readout circuit counts the number of the event signals read out from the pixel region, and when the number of the counted event signals exceeds a preset threshold within a predetermined period, the readout circuit discards the event signals read out from the pixel region, and transmits an acknowledge signal to the pixel region,

the pixel comprises a light amount variation detector, the light amount variation detector comprising:

a photodiode configured to output a photocurrent corresponding to a quantity of incident light,

a current/voltage converter configured to convert the photocurrent into a signal potential,

a subtractor configured to output a potential corresponding to a difference between the signal potential and a reference potential, and

a comparator configured to compare an output from the subtractor with a threshold and output a signal when an output from the subtractor exceeds the threshold, and

the light amount variation detector updates the reference potential with the signal potential in accordance with the acknowledge signal.

17 . An image capturing apparatus comprising:

a pixel region having a plurality of pixels configured to generate and output event signals upon detecting a variation in quantity of incident light; and

a readout circuit configured to read out the event signals output from the pixel region,

wherein the readout circuit counts the number of the event signals read out from the pixel region, and when the number of the counted event signals exceeds a preset threshold within a predetermined period, the readout circuit discards the event signals read out from the pixel region, and transmits an acknowledge signal to the pixel region,

the readout circuit further comprises an arbiter configured to arbitrate, when the pixel region generates a plurality of the event signals in a predetermined period, a readout order of the event signals from among the plurality of event signals, and

the arbiter further comprises a priority determination unit configured to hold priority corresponding to a readout order of the event signals and performs the arbitration based on the priority.