Light receiving device and distance measuring device
According to the present embodiment, a light receiving device includes a plurality of pixels. Each of the pixels includes a photoelectric conversion element configured to be able to detect incidence of a photon and a power supply portion configured to change an applied voltage applied across both ends of the photoelectric conversion element.
1 . A distance measuring device comprising:
a light receiving device including a plurality of pixels; and
a processor configured to control the light receiving device,
wherein
each of the pixels comprises:
a photoelectric conversion element that detects incidence of a photon;
a first power supply configured to supply a voltage to an anode side of the photoelectric conversion element for each pixel; and
a second power supply configured to supply a voltage to a cathode side of the photoelectric conversion element for each pixel or each pixel group including one or more pixels,
the voltage of the first power supply is changeable independently for each photoelectric conversion element, and
the processor is configured to control at least one of the first power supply and the second power supply, to control voltage between terminals of the photoelectric conversion elements so that the voltage between terminals of the photoelectric conversion elements is lowered in the order of a measurement pixel used for normal measurement, a preparing pixel that performs multiplication when a light intensity exceeds a predetermined level, and a non-measurement pixel that is not used for measurement.
2 . The distance measuring device of claim 1 , wherein the processor makes a fluctuation range of the voltage of the first power supply larger than a fluctuation range of the voltage of the second power supply.
3 . The distance measuring device of claim 1 , wherein the processor makes the fluctuation range of the voltage of the first power supply smaller than the fluctuation range of the voltage of the second power supply.
4 . The distance measuring device of claim 1 , wherein the photoelectric conversion element is a photodiode.
5 . The distance measuring device of claim 1 , wherein the voltage of the first power supply and the voltage of the second power supply are changeable independently for each pixel or each pixel group including one or more pixels.
6 . The distance measuring device of claim 2 , wherein the first power supply supplies the voltage to the photoelectric conversion element included in each of the pixels.
7 . The distance measuring device of claim 2 , wherein the processor makes an absolute value of the applied voltage in a measurement state larger than the applied voltage in a non-measurement state.
8 . The distance measuring device of claim 2 , wherein the pixel is configured by elements on a high breakdown voltage side and elements on a low breakdown voltage side, the first power supply is one of the elements on the high breakdown voltage side, and the second power supply is one of the elements on the low breakdown voltage side.
9 . The distance measuring device of claim 6 , wherein the processor sets each of the pixels in the measurement state in accordance with a magnitude of an output signal that is based on the photoelectric conversion element in the non-measurement state.
10 . The distance measuring device of claim 7 , wherein the processor changes a magnitude of the applied voltage in the non-measurement state in at least two steps.
11 . The distance measuring device of claim 9 , wherein the processor sets each of the pixels in the measurement state when the output signal is smaller than a predetermined value.
12 . The distance measuring device of claim 9 , wherein the processor changes a magnitude of the applied voltage in accordance with a temperature of the photoelectric conversion element.
13 . The distance measuring device of claim 12 , wherein the processor makes the magnitude of the applied voltage larger with increase of the temperature of the photoelectric conversion element.
14 . The distance measuring device of claim 13 , further comprising:
a first optical element that irradiates a measurement object with laser light while changing an emission direction of the laser light; and
a second optical element that receives reflected light of the laser light irradiated by the first optical element,
wherein the light receiving device converts the reflected light received through the second optical element to an electrical signal.
15 . The distance measuring device of claim 14 , wherein the photoelectric conversion element is a Geiger-mode avalanche photodiode.