Imaging device and camera system including sense circuits to make binary decision
An imaging device includes: a pixel array section having an array of pixels, each of which has a photoelectric converting device and outputs an electric signal according to an input photon; a sense circuit section having a plurality of sensor circuits each of which makes binary decision on whether there is a photon input to a pixel in a predetermined period upon reception of the electric signal therefrom; and a decision result IC section which integrates decision results from the sense circuits, pixel by pixel or for each group of pixels, multiple times to generate imaged data with a gradation, the decision result IC section including a count circuit which performs a count process to integrate the decision results from the sense circuits, and a memory for storing a counting result for each pixel from the count circuit, the sense circuits sharing the count circuit for integrating the decision results.
1. An imaging device comprising:
a pixel array section configured to have an array of pixels, each of which has a photoelectric converting device and outputs an electric signal according to an input photon;
a sense circuit section configured to have a plurality of sense circuits, each of which makes a binary decision on whether there is a photon input to a pixel in a predetermined period upon reception of the electric signal therefrom;
a decision result IC section configured to integrate decision results from the sense circuits; and
wherein the sense circuits include at least two switch elements, a circuit element, and a memory element, and the memory element is located between one of the at least two switch elements and the circuit element.
2. The imaging device according to claim 1 , wherein the memory element is a capacitor.
3. The imaging device according to claim 1 , wherein the circuit element is an inverter.
4. The imaging device according to claim 1 , wherein
the plurality of pixels in the pixel array section and the plurality of sense circuits in the sense circuit section are formed in one-to-one correspondence and are connected together respectively, and
every predetermined number of sense circuits in the plurality of sense circuits share a respective count circuit.
5. The imaging device according to claim 4 , wherein
the pixel array section has the plurality of pixels laid out in a matrix form in a row direction and in a column direction,
the sense circuit section has the plurality of sense circuits laid out in a matrix form in a row direction and in a column direction and the plurality of sense circuits are connected in one-to-one correspondence to the plurality of pixels in the pixel array section, and
sense circuits in the plurality of sense circuits which are located in a same row or a same column share a respective count circuit.
6. The imaging device according to claim 1 , further comprising a count circuit shared by a plurality of pixels.
7. The imaging device according to claim 6 , wherein
the pixel array section has a plurality of pixel blocks formed therein, each including a plurality of pixels and a selection element thereof, and
the sense circuit section has independent sense circuits arranged therein in association with the pixel blocks.
8. The imaging device according to claim 7 , wherein
the selection element in the sense circuit section cyclically selects each pixel in a pixel block, and outputs a signal of the selected pixel to a respective independent sense circuit, and
the respective independent sense circuit makes a decision on whether a photon is input to each pixel in a given period from previous selection to current selection.
9. The imaging device according to claim 8 , having a reset function of resetting each of the pixels to a state where a photon is not input, and an adjustment function of adjusting an exposure period by inserting a reset process to set the exposure period constant for the individual pixels between selective outputting of each pixel and next selective outputting in the pixel block.
10. The imaging device according to claim 1 , having a reset function of resetting each of the pixels to a state where a photon is not input, wherein each of the sense circuits carries out the binary decision by reading a signal in a reset state and a read signal after exposure, and comparing the signals one of which is added with an offset with each other.
11. The imaging device according to claim 1 , wherein
the decision result IC section has a function of adding count values for a plurality of pixels via a count circuit shared by the pixels.
12. The imaging device according to claim 1 , wherein
the sense circuit section has a function of repeatedly executing binary decision in a unit frame period multiple times, and integrating the decision results to derive an amount of photons input to a light receiving section, and a function of variably setting a cycle period of the decision within a range of a plurality of cycle periods according to N times a unit cycle period (N being an integer).
13. The imaging device according to claim 12 , including a mode of carrying out derivation of the amount of photons input in a same unit frame period in a small number of decisions over a long cycle period, and a mode of carrying out the derivation of the amount of photons input in a large number of decisions over a short cycle period.
14. The imaging device according to claim 13 , wherein
a plurality of decisions including a decision in a short cycle period and a decision in a long cycle period are further cyclically made in the unit frame period, results of the decisions are combined and integrated to derive an amount of photons input to the light receiving section.
15. The imaging device according to claim 12 , wherein
a small number of decisions are made over a long cycle period in imaging at low illuminance, and a large number of decisions are made over a short cycle period in imaging at high illuminance.
16. A system comprising:
a lens to guide input light; and
an imaging device to receive input light from the lens, the imaging device including
a pixel array section configured to have an array of pixels, each of which has a photoelectric converting device and outputs an electric signal according to an input photon,
a sense circuit section configured to have a plurality of sense circuits, each of which makes a binary decision on whether there is a photon input to a pixel in a predetermined period upon reception of the electric signal therefrom, and
a decision result IC section configured to integrate decision results from the sense circuits;
wherein the sense circuits include at least two switch elements, a circuit element, and a memory element, and the memory element is located between one of the at least two switch elements and the circuit element.
17. The system according to claim 16 , wherein the memory element is a capacitor.
18. The system according to claim 16 , wherein the circuit element is an inverter.