Photodetector circuit and photodetector device

1. A photodetector circuit comprising:

a photodetector transistor;

a current output transistor;

a switching transistor; and

a first capacitor,

wherein a source of the photodetector transistor, a gate of the current output transistor, and a first terminal of the first capacitor are connected to one another,

a source of the current output transistor, a drain of the switching transistor, and a second terminal of the first capacitor are connected to one another,

the photodetector transistor has a drain connected to a reference potential line, and upon receiving light when the photodetector transistor is in an off state, the source of the photodetector transistor collects electric charges generated by an internal photoelectric effect,

the current output transistor has a drain connected to a power line which can have a first power supply potential and a second power supply potential, and

the switching transistor has a source connected to a photodetection line.

2. The photodetector circuit according to claim 1 ,

wherein the first power supply potential is for causing the source of the current output transistor to have a potential lower than a potential of the gate of the current output transistor by a threshold voltage of the current output transistor, and

the second power supply potential is lower than the first power supply potential, and is for causing the source and the drain of the current output transistor to have an approximately same potential.

3. The photodetector circuit according to claim 1 ,

wherein the source and the drain of the current output transistor have an approximately same potential in a photodetection period which is at least part of a period during which the photodetector transistor is in an off state.

4. The photodetector circuit according to claim further comprising

a second capacitor connected to the second terminal and a fixed power supply.

5. The photodetector circuit according to claim 1 ,

wherein the reference potential line can have a first reference potential and a second reference potential.

6. The photodetector circuit according to claim 5 ,

wherein the second reference potential is higher than the first reference potential, and

when the photodetector transistor is in an on state, the gate of the current output transistor has the first reference potential, and the source of the current output transistor has a first potential lower than the first reference potential by a threshold voltage of the current output transistor, the second reference potential is for causing the gate of the current output transistor to have the second reference potential to cause the source of the current output transistor to have a potential higher than the first potential.

7. A photodetector device comprising

a photodetector circuit array including a plurality of the photodetector circuits arrayed two-dimensionally in N rows and M columns, each of the photodetector circuits being the photodetector circuit according to claim 1 , each of N and M being an integer greater than or equal to two,

wherein M photodetector circuits in each row are connected to a common reference potential line,

M photodetector circuits in each row are connected to a common power line, and

N photodetector circuits in each column are connected to a common photodetection line.

8. The photodetector device according to claim 7 , further comprising

a reference potential line drive circuit which drives the reference potential lines for two or more rows at a same time.