Light detection device and electronic apparatus comprising plural SPAD arrays with a photon detection rate controller
A first SPAD array on which at least one first light beam that is at least one pulse light beam is incident and which is operated in Geiger mode, a second SPAD array on which at least one second light beam resulting from the at least one first light beam reflected by a detection object is incident and which is operated in Geiger mode, a voltage generation unit that applies a reverse bias voltage to the first SPAD array and the second SPAD array, and a SPAD photon detection rate controller that adjusts and controls a SPAD photon detection rate in accordance with a first photon detection rate indicating a rate of the number of at least one pulse signal output by the second SPAD array upon incidence of the at least one second light beam relative to the number of the at least one pulse light beam are included.
1. A light detection device comprising:
a first SPAD array on which at least one first light beam that is at least one pulse light beam emitted from a light-emitting unit is incident and which is operated in Geiger mode;
a second SPAD array on which at least one second light beam resulting from the at least one first light beam reflected by a detection object is incident and which is operated in Geiger mode;
a voltage generation unit that applies a reverse bias voltage to the first SPAD array and the second SPAD array; and
a SPAD photon detection rate controller that adjusts and controls a SPAD photon detection rate in accordance with a first photon detection rate indicating a rate of the number of at least one pulse signal output by the second SPAD array upon incidence of the at least one second light beam relative to the number of the at least one pulse light beam.
2. The light detection device according to claim 1 , wherein the SPAD photon detection rate controller controls a light emission amount of the light-emitting unit in accordance with whether or not the first photon detection rate exceeds a first setting value that is set in advance.
3. The light detection device according to claim 1 , wherein the SPAD photon detection rate controller controls the voltage generation unit in accordance with whether or not the first photon detection rate exceeds a first setting value that is set in advance.
4. The light detection device according to claim 1 , wherein the SPAD photon detection rate controller controls the number of SPADs that constitute at least one SPAD array of the first SPAD array and the second SPAD array in accordance with whether or not the first photon detection rate exceeds a first setting value that is set in advance.
5. The light detection device according to claim 1 , wherein the SPAD photon detection rate controller controls a light emission amount of the light-emitting unit in accordance with whether or not the second SPAD array is in a saturated operation region above a normal operation region due to incidence of the at least one second light beam.
6. The light detection device according to claim 1 , wherein the SPAD photon detection rate controller performs control so that the first photon detection rate is 30% or more and 70% or less.
7. The light detection device according to claim 1 , wherein the SPAD photon detection rate controller controls a light emission amount of the light-emitting unit before a distance between the light detection device and the detection object is measured.
8. The light detection device according to claim 1 , wherein the SPAD photon detection rate controller controls a light emission amount of the light-emitting unit in accordance with a second photon detection rate indicating a rate of the number of at least one pulse signal output by the first SPAD array upon incidence of the at least one first light beam relative to the number of the at least one pulse light beam.
9. The light detection device according to claim 1 further comprising:
a histogram generation unit that generates a first histogram based on at least one pulse signal output by the first SPAD array and a second histogram based on the at least one pulse signal output by the second SPAD array; and
a distance calculation unit that calculates a distance between the light detection device and the detection object in accordance with a center of gravity of the first histogram that is generated by the histogram generation unit and a center of gravity of the second histogram that is generated by the histogram generation unit.
10. An electronic apparatus comprising the light detection device according to claim 1 .