JP7309332B2 - Control device, sensor device, control method and program - Google Patents

Description

The present invention relates to a control device, a sensor device, a control method and a program.

A detector for detecting light may include an avalanche photodiode (APD). APDs have high sensitivity due to avalanche breakdown, allowing detection of high single photons. However, when the intensity of input light is high, the APD may not be able to obtain good output characteristics due to the space charge effect.

Patent Literature 1 describes an example of a structure for alleviating the space charge effect of APDs. This structure includes undoped InGaAs (first light absorption layer), p-type InGaAs (second light absorption layer), undoped InAlGaAs (gap continuous layer), p-type InGaAs (electric field control layer), and undoped InAlAs ( avalanche layer). Patent Document 1 describes that in this structure, holes are accelerated in the vicinity of the avalanche layer, and the space charge effect is alleviated.

JP 2015-170686 A

The present inventor studied the output signal characteristics of an APD. Specifically, when pulsed light is repeatedly incident on the APD while a reverse bias voltage is constantly applied to the APD, the output signal of the APD decreases over time. I found what I could do.

One example of the problem to be solved by the present invention is to suppress the decrease in the output signal of the avalanche diode.

The invention according to claim 1,
a control circuit for controlling a first avalanche diode having an anode and a cathode;
The control circuit is
in a first period, setting the voltage of the cathode to the anode of the first avalanche diode in a range above a first value;
setting the voltage of the cathode with respect to the anode of the first avalanche diode in a range equal to or lower than a first value in a second period after the first period;
A controller for setting the voltage of the cathode with respect to the anode of the first avalanche diode to a range greater than a first value during a third period after the second period.

The invention according to claim 7,
an electromagnetic source;
a first avalanche diode having an anode and a cathode for detecting electromagnetic waves emitted from the electromagnetic wave source;
a control circuit for controlling the first avalanche diode;
including
The control circuit is
in a first period, setting the voltage of the cathode to the anode of the first avalanche diode in a range above a first value;
setting the voltage of the cathode with respect to the anode of the first avalanche diode in a range equal to or lower than a first value in a second period after the first period;
In the sensor device, the voltage of the cathode with respect to the anode of the first avalanche diode is set to a range above a first value during a third period after the second period.

The invention according to claim 8,
A control method for controlling a first avalanche diode having an anode and a cathode by a control circuit, comprising:
By the control circuit,
in a first period, setting the voltage of the cathode to the anode of the first avalanche diode in a range above a first value;
setting the voltage of the cathode with respect to the anode of the first avalanche diode in a range equal to or lower than a first value in a second period after the first period;
In the control method, the voltage of the cathode with respect to the anode of the first avalanche diode is set in a range exceeding a first value in a third period after the second period.

The invention according to claim 9,
A program for causing a computer to function as a control device for controlling a first avalanche diode having an anode and a cathode,
to the computer;
setting the voltage of the cathode to the anode of the first avalanche diode in a range above a first value in a first period;
setting the voltage of the cathode with respect to the anode of the first avalanche diode to a range equal to or less than a first value in a second period after the first period;
The program causes the voltage of the cathode with respect to the anode of the first avalanche diode to be set in a range exceeding a first value in a third period after the second period.

1 is a diagram for explaining a control device according to Embodiment 1; FIG. 3 is a diagram showing a time chart for explaining an example of control by the control device shown in FIG. 1; FIG. 2 is a diagram for explaining an example of the detection device shown in FIG. 1; FIG. FIG. 7 is a diagram for explaining a control device according to Embodiment 2; 5 is a diagram showing a time chart for explaining an example of control by the control device shown in FIG. 4; FIG. 5 is a diagram for explaining an example of the detection device shown in FIG. 4; FIG. 1 is a diagram for explaining a sensor device according to Example 1; FIG. 8 is a diagram showing a time chart for explaining a first example of control by the control device shown in FIG. 7; FIG. 8 is a diagram showing a time chart for explaining a second example of control by the control device shown in FIG. 7; FIG. 8 is a diagram showing a time chart for explaining a third example of control by the control device shown in FIG. 7; FIG. 8 is a diagram showing a time chart for explaining a fourth example of control by the control device shown in FIG. 7; FIG. FIG. 10 is a diagram for explaining a sensor device according to Example 2; 13 is a diagram showing a time chart for explaining an example of control by the control device shown in FIG. 12; FIG. FIG. 11 is a circuit diagram for explaining a detection device according to Example 3; 10 is a graph showing measurement results of the amplitude of the output signal of the first AD in the detection device according to Example 3. FIG. 7 is a graph showing measurement results of the amplitude of the output signal of the first AD in the detection device according to the comparative example; FIG. 11 is a diagram for explaining a sensor device according to Example 4; It is a figure for demonstrating the detection apparatus which concerns on a modification.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In addition, in all the drawings, the same constituent elements are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

(Embodiment 1)
FIG. 1 is a diagram for explaining the control device 300 according to the first embodiment. FIG. 2 is a diagram showing a time chart for explaining an example of control by control device 300 shown in FIG.

An outline of the control device 300 will be described with reference to FIGS. 1 and 2. FIG. Control device 300 includes a control circuit 310 . A control circuit 310 is for controlling the first avalanche diode (AD) 210 . The first AD 210 has an anode A and a cathode K. As shown in FIG. 2, the control circuit 310 sets the voltage V1 of the cathode K with respect to the anode A of the first AD 210 to a range exceeding the first value Vth1 in the first period (for example, period P1 or period P3). The control circuit 310 sets the voltage V1 of the cathode K with respect to the anode A of the first AD 210 to a range equal to or lower than the first value Vth1 in a second period (for example, period P2 or period P4) after the first period. The control circuit 310 sets the voltage V1 of the cathode K with respect to the anode A of the first AD 210 to a range exceeding the first value Vth1 in a third period (for example, period P3 or period P5) after the second period.

According to the configuration described above, it is possible to suppress a decrease in the output signal of the first AD 210 . As will be described later, the inventors have found that the output signal of the first AD 210 may decrease over time when an electromagnetic wave is incident on the first AD 210 while a reverse bias voltage is constantly applied to the first AD 210 . The present inventor studied a method for suppressing the drop in the output signal of the first AD 210 and found that the reverse bias voltage of the first AD 210 was temporarily relaxed. In the above-described configuration, in the second period from the first period to the third period (for example, the period P2 from the period P1 to the period P3 or the period P4 from the period P3 to the period P5), the first AD 210 temporarily relaxes the reverse bias voltage of Therefore, a decrease in the output signal of the first AD 210 can be suppressed.

Details of the detection device 200 and the control device 300 will be described with reference to FIG. Detection device 200 includes a first AD 210 . Control device 300 includes a control circuit 310 .

The first AD 210 can detect electromagnetic waves, and in the example shown in FIG. 1, can detect light (eg, visible light, infrared light, or ultraviolet light). In the example shown in FIG. 1, the first AD 210 may be an avalanche photodiode (APD). In other examples, the first AD 210 may be capable of detecting electromagnetic waves other than light, such as radio waves or electromagnetic radiation (eg, gamma rays or X-rays).

In one example, controller 300 may be a computer. In this example, the program can cause the computer to function as the control device 300 .

Details of the control of the control circuit 310 will be described with reference to FIG.

In the example shown in FIG. 2, the first value Vth1 is 0V. The first value Vth1 is set such that the voltage V1 of the first AD 210 is equal to or higher than the breakdown voltage and the voltage of the first AD 210 is equal to or higher than the breakdown voltage in periods (periods P1, P3, and P5) in which the voltage V1 of the first AD 210 exceeds the first value Vth1. In the period (periods P2 and P4) in which V1 is equal to or less than the first value Vth1, the voltage V1 of the first AD 210 may be set to 0V or a value different from 0V as long as the voltage V1 is less than the breakdown voltage.

In the example shown in FIG. 2, the control circuit 310 keeps the voltage V1 of the first AD 210 constant regardless of time during periods (periods P1, P3, and P5) in which the voltage V1 of the first AD 210 exceeds the first value Vth1. is set to In another example, the control circuit 310 may time-dependently vary the voltage V1 of the first AD 210 during the period.

In the example shown in FIG. 2, the control circuit 310 keeps the voltage V1 of the first AD 210 constant (first value Vth: 0V). In another example, the control circuit 310 sets the voltage V1 of the first AD 210 to a voltage different from 0 V, such as a negative voltage (that is, increases the potential of the anode A with respect to the cathode K) during the period. may In yet another example, the control circuit 310 may time-dependently vary the voltage V1 of the first AD 210 during the period.

The control circuit 310 controls the period during which the voltage V1 of the first AD 210 exceeds the first value Vth1 (periods P1, P3, and P5) and the period during which the voltage V1 of the first AD 210 is equal to or less than the first value Vth1 (periods P2 and P4). are alternately repeated. Thus, the control circuit 310 temporarily relaxes the reverse bias voltage of the first AD 210 . Therefore, a decrease in the output signal of the first AD 210 can be suppressed.

In the example shown in FIG. 2, the control circuit 310 periodically applies a reverse bias voltage exceeding the first value Vth1. In another example, the control circuit 310 may aperiodically apply a reverse bias voltage greater than the first value Vth1 to the first AD 210 .

FIG. 3 is a diagram for explaining an example of the detection device 200 shown in FIG. The upper part of FIG. 3 is a perspective view of the detection device 200, and the lower part of FIG. 3 is a top view of the detection device 200. As shown in FIG.

Sensing device 200 includes sensing surface 402 , terminals 412 and terminals 414 .

Detection surface 402 constitutes at least a portion of first AD 210 . The detection device 200 can detect electromagnetic waves incident on the detection surface 402 .

The terminal 412 constitutes the anode A of the first AD 210 and the terminal 414 constitutes the cathode K of the first AD 210 .

(Embodiment 2)
FIG. 4 is a diagram for explaining the control device 300 according to the second embodiment. FIG. 5 is a diagram showing a time chart for explaining an example of control by control device 300 shown in FIG. The control device 300 according to this embodiment is the same as the control device 300 according to the first embodiment except for the following points.

The control circuit 310 is for controlling a plurality of avalanche diodes, and in the example shown in FIG. 4, for controlling the first AD 210 and the second AD 220 . The second AD 220 has an anode A and a cathode K, similar to the first AD 210 .

As shown in FIG. 5, the control circuit 310 sets the voltage V1 of the cathode K with respect to the anode A of the first AD 210 in a range exceeding the first value Vth1 in the first period (for example, the period P1 or the period P3). , the voltage V2 of the cathode K with respect to the anode A of the second AD 220 is set to a range equal to or less than the second value Vth2. In a second period (for example, period P2 or period P4) after the first period, the control circuit 310 sets the voltage V1 of the cathode K with respect to the anode A of the first AD 210 to a range equal to or lower than the first value Vth1. The voltage V2 of the cathode K with respect to the anode A of the 2AD220 is set in a range exceeding the second value Vth2. In a third period (for example, period P3 or period P5) after the second period, the control circuit 310 sets the voltage V1 of the cathode K with respect to the anode A of the first AD 210 to a range exceeding the first value Vth1. The voltage V2 of the cathode K with respect to the anode A of the 2AD220 is set within the range of the second value Vth2 or less.

According to the configuration described above, it is possible to suppress a decrease in the output signal of the first AD 210 and a decrease in the output signal of the second AD 220, and to operate the first AD 210 and the second AD 220 complementarily. Specifically, in the above-described configuration, during a period in which the reverse bias voltage of the first AD 210 is relaxed (that is, a period during which the first AD 210 cannot detect electromagnetic waves) (for example, period P2 or period P4), the second A reverse bias voltage is applied to the second AD 220 so that the second AD 220 can detect electromagnetic waves, and the period during which the reverse bias voltage of the second AD 220 is relaxed (that is, the period during which the second AD 220 cannot detect electromagnetic waves) ) (for example, period P1, period P3, or period P5), a reverse bias voltage is applied to the first AD 210 so that the first AD 210 can detect electromagnetic waves. Therefore, the first AD 210 and the second AD 220 can be operated complementarily.

Details of the control of the control circuit 310 will be described with reference to FIG.

In the example shown in FIG. 5, the second value Vth2 is equal to the first value Vth1, which is 0V. In another example, the second value Vth may be different from the first value Vth1, or may be a voltage other than 0V.

In the example shown in FIG. 5 , the voltage V2 of the cathode K with respect to the anode A of the second AD 220 is set to It is equal to or less than the second value Vth. In another example, the voltage V2 of the cathode K with respect to the anode A of the second AD 220 is only during a part of the period (for example, the period P1, the period P3, or the period P5) when the voltage V1 of the first AD 210 exceeds the first value Vth1. It may be equal to or less than the second value Vth. Also in this example, the decrease in the output signal of the second AD 220 can be suppressed.

In the example shown in FIG. 5, the voltage V2 of the cathode K with respect to the anode A of the second AD 220 is the second value for the entire period (for example, period P2 or period P4) in which the voltage V1 of the first AD 210 is equal to or less than the first value Vth1. Vth is exceeded. In another example, the voltage V2 of the cathode K with respect to the anode A of the second AD 220 is the second value only during a portion of the period (for example, the period P2 or the period P4) in which the voltage V1 of the first AD 210 is equal to or less than the first value Vth1. Vth may be exceeded. Also in this example, the first AD 210 and the second AD 220 can be operated complementarily.

FIG. 6 is a diagram for explaining an example of the detection device 200 shown in FIG. The upper part of FIG. 6 is a perspective view of the detection device 200, and the lower part of FIG. 6 is a top view of the detection device 200. As shown in FIG.

The sensing device 200 includes a sensing surface 402, a terminal 412a (terminal 412), a terminal 414a (terminal 414), a terminal 412b (terminal 412) and a terminal 414b (terminal 414).

The detection surface 402 includes a plurality of detection surfaces, and includes a first detection surface 402a and a second detection surface 402b in the example shown in FIG. The first detection surface 402a and the second detection surface 402b are aligned with each other and oriented in the same direction. The first detection surface 402a constitutes at least a portion of the first AD210. The second detection surface 402b constitutes at least a portion of the second AD220. Therefore, the first AD 210 and the second AD 220 are capable of detecting electromagnetic waves irradiated to the detection device 200 from the same direction.

The terminal 412 a constitutes the anode A of the first AD 210 , and the terminal 414 a constitutes the cathode K of the first AD 210 . The terminal 412 b constitutes the anode A of the second AD 220 and the terminal 414 b constitutes the cathode K of the second AD 220 .

(Example 1)
FIG. 7 is a diagram for explaining the sensor device 10 according to the first embodiment.

The sensor device 10 includes an electromagnetic wave source 100 , a detection device 200 and a control device 300 . Detection device 200 includes a first AD 210 . The first AD 210 is for detecting electromagnetic waves emitted from the electromagnetic wave source 100 . Control device 300 includes a control circuit 310 . The control circuit 310 is for controlling the first AD 210 in the same manner as in the first embodiment (FIG. 1). Therefore, as in the first embodiment (FIG. 1), the decrease in the output signal of the first AD 210 can be suppressed.

The electromagnetic wave source 100 can emit electromagnetic waves (for example, light or radio waves). If the emitted electromagnetic wave is light, the electromagnetic wave source 100 may be, for example, a laser diode (LD).

The first AD 210 detects electromagnetic waves emitted from the electromagnetic wave source 100 and reflected by objects. In one example, the sensor device 10 can measure the distance from the sensor device 10 to the object based on the time from when the electromagnetic wave is emitted from the electromagnetic wave source 100 to when the electromagnetic wave is detected by the first AD 210 .

In one example, the sensor device 10 may be a LiDAR (Light Detection And Ranging). In this example, the electromagnetic wave source 100 emits light and the detector 200 (first AD 210) detects the light. In another example, the sensor device 10 may be a RADAR (RADio Detection And Ranging). In this example, the electromagnetic wave source 100 emits radio waves, and the detection device 200 (first AD 210) detects the radio waves.

FIG. 8 is a diagram showing a time chart for explaining a first example of control by control device 300 shown in FIG. The upper part of FIG. 8 shows the time chart of the electromagnetic wave emitted from the electromagnetic wave source 100, the middle part of FIG. 8 shows the time chart of the voltage V1 of the first AD 210, and the lower part of FIG. 2 shows a time chart of output signals (for example, photocurrent flowing from the first AD 210).

The control circuit 310 controls the voltage of the first AD 210 after the electromagnetic wave is incident on the first AD 210 in the first period (the period in which the reverse bias voltage of the first AD 210 exceeds the first value Vth1, for example, the period P1, the period P3, or the period P5). V1 is switched from a value greater than the first value Vth1 to a value equal to or less than the first value Vth, and transitions to a second period (for example, period P2, period P4, or period P6).

According to the configuration described above, it is possible to suppress a decrease in the output signal of the first AD 210 and to detect the electromagnetic wave by the first AD 210 with high reliability. Specifically, in the configuration described above, after the electromagnetic wave enters the first AD 210 (that is, after the first AD 210 no longer needs to detect further electromagnetic waves), the reverse bias voltage of the first AD 210 is temporarily relaxed. there is Therefore, electromagnetic waves can be detected by the first AD 210 with high reliability.

Details of the control of the control circuit 310 will be described with reference to FIG.

In the example shown in FIG. 8, the electromagnetic wave source 100 periodically emits electromagnetic waves at a period T. In the example shown in FIG. In another example, electromagnetic wave source 100 may emit electromagnetic waves aperiodically.

The first AD 210 detects electromagnetic waves emitted from the electromagnetic wave source 100 and reflected from objects. As the distance from the sensor device 10 to the object increases, the propagation time of the electromagnetic wave increases and the electromagnetic wave tends to attenuate. In the example shown in FIG. 8, the first output signal of the first AD 210 can be said to be generated by the electromagnetic wave reflected by the object closest to the sensor device 10 among the three output signals of the first AD 210. It can be said that the third output signal of the first AD 210 is generated by the electromagnetic waves reflected by the farthest object from the sensor device 10 among the three output signals of the first AD 210 .

FIG. 9 is a diagram showing a time chart for explaining a second example of control by control device 300 shown in FIG. The example shown in FIG. 9 is similar to the example shown in FIG. 8, except for the following points.

The electromagnetic wave source 100 emits one electromagnetic wave in a second period (a period in which the reverse bias voltage of the first AD 210 is equal to or lower than the first value Vth1, eg, period P1, period P3, or period P5). After the electromagnetic wave source 100 emits one electromagnetic wave, the control circuit 310 switches the voltage V1 of the first AD 210 from a value lower than the first value Vth1 to a value higher than the first value Vth1 for a third period (reverse bias of the first AD 210 A transition is made to a period in which the voltage exceeds the first value Vth1, for example, period P2, period P4, or period P6).

According to the configuration described above, it is possible to suppress a decrease in the output signal of the first AD 210 and to allow the sensor device 10 to selectively detect an object separated from the sensor device 10 by a specific distance or more. Specifically, in the configuration described above, the reverse bias voltage of the first AD 210 is temporarily relaxed for a certain period from the timing when the electromagnetic wave source 100 emits the electromagnetic waves. The electromagnetic wave irradiated to the first AD 210 during this period is the electromagnetic wave reflected from an object located at a short distance from the sensor device 10 and cannot be detected by the first AD 210 . Therefore, it is possible to cause the sensor device 10 to selectively detect objects separated from the sensor device 10 by a specific distance or more.

FIG. 10 is a diagram showing a time chart for explaining a third example of control by control device 300 shown in FIG. The example shown in FIG. 10 is similar to the example shown in FIG. 8, except for the following points.

The control circuit 310 reduces the voltage V1 of the first AD 210 to the first AD 210 after the electromagnetic wave is incident on the first AD 210 in the first period (the period in which the reverse bias voltage of the first AD 210 exceeds the first value Vth1, for example, the period P2 or the period P4). A value greater than one value Vth1 is switched to a value equal to or less than the first value Vth to shift to a second period (a period in which the reverse bias voltage of the first AD 210 is equal to or less than the first value Vth1, for example, period P3 or period P5). . The electromagnetic wave source 100 emits one electromagnetic wave in the second period (for example, period P3 or period P5). After the electromagnetic wave source 100 emits one electromagnetic wave, the control circuit 310 switches the voltage V1 of the first AD 210 from a value lower than the first value Vth1 to a value higher than the first value Vth1 for a third period (reverse bias of the first AD 210 A transition is made to a period in which the voltage exceeds the first value Vth1, for example, period P4 or period P6).

According to the above-described configuration, it is possible to suppress a decrease in the output signal of the first AD 210, and similarly to the example described with reference to FIG. 9, it is possible to cause the sensor device 10 to selectively detect objects separated from the sensor device 10 by a specific distance or more.

FIG. 11 is a diagram showing a time chart for explaining a fourth example of control by control device 300 shown in FIG. The example shown in FIG. 11 is similar to the example shown in FIG. 8, except for the following points.

The control circuit 310 gradually increases the voltage V1 of the first AD 210 in the first period (the period in which the reverse bias voltage of the first AD 210 exceeds the first value Vth1, eg, period P1, period P3, or period P5). Similarly to the example shown in FIG. 8, after the electromagnetic wave is incident on the first AD 210 in the first period, the control circuit 310 changes the voltage V1 of the first AD 210 from a value exceeding the first value Vth1 to a value equal to or less than the first value Vth. to the second period (for example, period P3 or period P5).

According to the configuration described above, it is possible to suppress a decrease in the output signal of the first AD 210 and to apply an appropriate reverse bias voltage according to the intensity of the electromagnetic wave incident on the first AD 210 . Specifically, the longer the distance from the sensor device 10 to the object (that is, the longer the time from the emission of the electromagnetic wave from the electromagnetic wave source 100 to the incidence of the electromagnetic wave on the first AD 210), the easier it is for the electromagnetic wave to attenuate. Therefore, when the time from the emission of the electromagnetic wave from the electromagnetic wave source 100 to the incidence of the electromagnetic wave on the first AD 210 is short, the voltage V1 of the first AD 210 may be small. If the time until the electromagnetic wave enters the 1AD 210 is long, the voltage V1 of the 1AD 210 should be increased. According to the above-described configuration, when the time from the emission of the electromagnetic wave from the electromagnetic wave source 100 to the incidence of the electromagnetic wave on the first AD 210 is short, the voltage V1 of the first AD 210 can be reduced, and the emission of the electromagnetic wave from the electromagnetic wave source 100 can be reduced. to the incidence of the electromagnetic wave on the first AD 210, the voltage V1 of the first AD 210 can be increased. Therefore, it is possible to apply a suitable reverse bias voltage according to the intensity of the electromagnetic waves incident on the first AD 210 .

In the example shown in FIG. 11, the control circuit 310 gradually increases the voltage V1 of the first AD 210 throughout the first period (for example, period P1, period P3, or period P5). In another example, the control circuit 310 may gradually increase the voltage V1 of the first AD 210 during only part of the first period. In this example, the control circuit 310 may set the voltage V1 of the first AD 210 constant irrespective of time during other portions of the first period.

In the example shown in FIG. 11, the control circuit 310 linearly increases the voltage V1 of the first AD 210 during the first period (for example, period P1, period P3, or period P5). In another example, the control circuit 310 may increase the voltage V1 of the first AD 210 non-linearly. In one example, the control circuit 310 may increase the voltage V1 of the first AD 210 stepwise.

(Example 2)
FIG. 12 is a diagram for explaining the sensor device 10 according to the second embodiment. The sensor device 10 according to the second embodiment is the same as the sensor device 10 according to the first embodiment except for the following points.

The sensor device 10 includes an electromagnetic wave source 100 , a detection device 200 and a control device 300 . Detecting device 200 includes first AD 210 and second AD 220 . The first AD 210 and the second AD 220 are for detecting electromagnetic waves emitted from the electromagnetic wave source 100 . Control device 300 includes a control circuit 310 . The control circuit 310 is for controlling the first AD 210 and the second AD 220 in the same manner as in the second embodiment (FIG. 4). Therefore, as in the second embodiment (FIG. 4), it is possible to suppress the decrease in the output signal of the first AD 210 and the decrease in the output signal of the second AD 220, and to operate the first AD 210 and the second AD 220 complementarily. .

FIG. 13 is a diagram showing a time chart for explaining an example of control by control device 300 shown in FIG. The first stage of FIG. 13 shows the time chart of the electromagnetic wave emitted from the electromagnetic wave source 100, the second stage of FIG. 13 shows the time chart of the voltage V1 of the first AD 210, and the third stage of FIG. 13 shows the time chart of the output signal of the first AD 210 (for example, the photocurrent flowing from the first AD 210), the fourth row of FIG. 13 shows the time chart of the voltage V2 of the second AD 220, and the The fifth stage shows a time chart of the output signal of the second AD 220 (for example, the photocurrent flowing from the second AD 220).

In the example shown in FIG. 13, the control circuit 310 controls the period (period P1 and period P3) during which the voltage V1 of the first AD 210 exceeds the first value Vth1 and the period during which the voltage V1 of the first AD 210 is equal to or less than the first value Vth1 (period P2) is alternately repeated in synchronization with the period T of emission of electromagnetic waves from the electromagnetic wave source 100 . The control circuit 310 sets the voltage V2 of the cathode K with respect to the anode A of the second AD 220 to a range equal to or lower than the second value Vth2 during periods (periods P1 and P3) in which the voltage V1 of the first AD 210 exceeds the first value Vth1. In the period (period P2) in which the voltage V1 of the first AD 210 is equal to or less than the first value Vth1, the voltage V2 of the cathode K with respect to the anode A of the second AD 220 is set in a range exceeding the second value Vth2. In this way, it is possible to suppress a decrease in the output signal of the first AD 210 and a decrease in the output signal of the second AD 220, and to operate the first AD 210 and the second AD 220 complementarily.

(Example 3)
FIG. 14 is a circuit diagram for explaining the detection device 200 according to the third embodiment.

A cathode K of the first AD 210 is connected to a power supply VV1 via a protective resistor Rlim and a ferrite bead Rfb1. A line for interconnecting the cathode K of the first AD 210 and the protection resistor Rlim is grounded via a capacitor Cph. An anode A of the first AD 210 is connected to a current-voltage conversion circuit T.

A current-voltage conversion circuit T converts the current flowing from the first AD 210 into a voltage. The current-voltage conversion circuit T includes an operational amplifier U1. An inverting input terminal of the operational amplifier U1 is connected to the anode A of the first AD210. A potential VCC is supplied to the non-inverting input terminal of the operational amplifier U1. A line for supplying the potential VCC to the non-inverting input terminal of the operational amplifier U1 is grounded via a bypass capacitor Cp. A feedback resistor Rf and a feedback capacitor Cf are connected in parallel between the output terminal and the inverting input terminal of the operational amplifier U1. The negative power supply terminal of operational amplifier U1 is grounded. A signal (voltage) is output from the output terminal of the operational amplifier U1. The output terminal of operational amplifier U1 is connected to the non-inverting input terminal of comparator U2.

A comparator U2 compares the voltage output from the output terminal of the operational amplifier U1 and the voltage of the power supply E, and if the voltage output from the output terminal of the operational amplifier U1 is greater than the voltage of the power supply E, a signal for turning on the transistor Q1. to output When the transistor Q1 is turned on, the potential of the cathode K of the first AD210 is lowered toward ground. In this way, for example, as shown in FIG. 8 or 10, after the electromagnetic wave is incident on the first AD 210 (that is, after the current flows from the first AD 210), the voltage V1 of the first AD 210 can be lowered.

A terminating resistor Ro and a capacitor Co are connected in series to a line for interconnecting the output terminal of the operational amplifier U1 and the non-inverting input terminal of the comparator U2. A signal (voltage Vout) corresponding to the current flowing from the first AD 210 is output from the capacitor Co.

Potential VCC is controlled by power supply VV2 connected via ferrite bead Rfb2.

The control circuit 310 of the control device 300 controls the voltage of the power supply VV1 and the voltage of the power supply VV2 to control the voltage of the cathode K with respect to the anode A of the first AD210. Specifically, the cathode K of the first AD 210 is connected to the power supply VV1. The anode A of the first AD 210 is connected to the inverting input terminal of the operational amplifier U1. Potential VCC is controlled by power supply VV2. Therefore, the voltage of the cathode K with respect to the anode A of the first AD 210 can be controlled by the voltage of the power supply VV1 and the voltage of the power supply VV2.

FIG. 15 is a graph showing measurement results of the amplitude of the output signal of the first AD 210 in the detection device 200 according to the third embodiment. FIG. 16 is a graph showing measurement results of the amplitude of the output signal of the first AD 210 in the detection device 200 according to the comparative example.

In the example shown in FIG. 15, pulsed light with a pulse width of 5 ns was incident on the first AD 210 at a period of 1 μs. The voltage between the anode A and the cathode K of the first AD 210 is set to 0 V for 15 to 20 seconds out of 30 seconds, and is set to the reverse bias voltage for the remaining period of 30 seconds (30 seconds). Let Note that in the example shown in FIG. 15, the comparator U2 shown in FIG. 14 is removed from the detector 200. FIG.

The example shown in FIG. 16 is the same as the example shown in FIG. 15 except that the voltage between the anode A and cathode K of the first AD 210 is always set to the reverse bias voltage.

In the comparative example, as shown in FIG. 16, the amplitude of the output signal of the first AD 210 decreased to about 50% of the initial amplitude after about 200 seconds from the start of measurement. On the other hand, in Example 3, as shown in FIG. 15, the amplitude of the output signal of the first AD 210 remained at about 80% of the initial amplitude even after about 200 seconds from the start of measurement. These results suggest that the decrease in the output signal of the first AD 210 can be suppressed by temporarily relaxing the reverse bias voltage of the first AD 210 .

(Example 4)
FIG. 17 is a diagram for explaining the sensor device 10 according to the fourth embodiment.

The sensor device 10 includes an electromagnetic wave source 100 , a detection device 200 , a control device 300 , a movable reflector 400 and a splitter 410 .

The electromagnetic wave source 100, the detection device 200 and the control device 300 are similar to the electromagnetic wave source 100, the detection device 200 and the control device 300 according to any of the embodiments described above. Therefore, a decrease in the output signal of the first AD 210 can be suppressed.

Movable reflector 400 is for reflecting electromagnetic waves emitted from electromagnetic wave source 100 toward the outside of sensor device 10 . The moveable reflector 400 allows electromagnetic waves to scan objects outside the sensor device 10 . In one example, the movable reflector 400 can be a Micro Electro Mechanical Systems (MEMS) mirror.

In the example shown in FIG. 17 , electromagnetic waves emitted from electromagnetic wave source 100 pass through splitter 410 and are reflected by movable reflector 400 . Electromagnetic waves emitted from the outside of sensor device 10 are reflected by movable reflector 400 and reflected toward detection device 200 by splitter 410 .

The structure for scanning an object outside sensor device 10 is not limited to movable reflector 400 . In another example, the electromagnetic wave source 100 and detector 200 may be mounted on a rotating stage to scan objects around the rotating stage.

(Modification)
FIG. 18 is a diagram for explaining a detection device 200 according to a modification.

As shown in FIG. 18, the detection device 200 may include a control device 300 (control circuit 310). In the example shown in FIG. 18 as well, the decrease in the output signal of the first AD 210 can be suppressed.

Although the embodiments and examples have been described above with reference to the drawings, these are examples of the present invention, and various configurations other than those described above can be adopted.
Examples of reference forms are added below.
1. a control circuit for controlling a first avalanche diode having an anode and a cathode;
The control circuit is
in a first period, setting the voltage of the cathode to the anode of the first avalanche diode in a range above a first value;
setting the voltage of the cathode with respect to the anode of the first avalanche diode in a range equal to or lower than a first value in a second period after the first period;
A controller for setting the voltage of the cathode with respect to the anode of the first avalanche diode to a range above a first value for a third time period after the second time period.
2. 1. In the control device according to
The control circuit adjusts the voltage of the cathode of the first avalanche diode with respect to the anode of the first avalanche diode after the electromagnetic wave is incident on the first avalanche diode in the first period from a value exceeding the first value to a value equal to or less than the first value. value to transition to the second time period.
3. 2. In the control device according to
The control device, wherein the control circuit gradually increases the voltage of the cathode with respect to the anode of the first avalanche diode during at least part of the first period.
4. 1. In the control device according to
The first avalanche diode is for detecting electromagnetic waves emitted from an electromagnetic wave source,
The electromagnetic wave source emits one electromagnetic wave in the second period,
The control circuit switches the voltage of the cathode with respect to the anode of the first avalanche diode from a value equal to or less than the first value to a value greater than the first value after the electromagnetic wave source emits the one electromagnetic wave. A control device that transitions to the third period.
5. 1. In the control device according to
The first avalanche diode is for detecting electromagnetic waves emitted from an electromagnetic wave source,
The control circuit adjusts the voltage of the cathode of the first avalanche diode with respect to the anode of the first avalanche diode after the electromagnetic wave is incident on the first avalanche diode in the first period from a value exceeding the first value to a value equal to or less than the first value. value and transition to the second period;
The electromagnetic wave source emits one electromagnetic wave in the second period,
The control circuit switches the voltage of the cathode with respect to the anode of the first avalanche diode from a value equal to or less than the first value to a value greater than the first value after the electromagnetic wave source emits the one electromagnetic wave. A control device that transitions to the third period.
6. 1. In the control device according to
the control circuit is also for controlling a second avalanche diode having an anode and a cathode;
The control circuit is
setting the voltage of the cathode with respect to the anode of the second avalanche diode to a range equal to or less than a second value in at least part of the first period;
setting the voltage of the cathode to the anode of the second avalanche diode in a range above a second value for at least part of the second period;
A controller for setting the voltage of the cathode with respect to the anode of the second avalanche diode to a range equal to or less than a second value during at least part of the third period.
7. an electromagnetic source;
a first avalanche diode having an anode and a cathode for detecting electromagnetic waves emitted from the electromagnetic wave source;
a control circuit for controlling the first avalanche diode;
including
The control circuit is
in a first period, setting the voltage of the cathode to the anode of the first avalanche diode in a range above a first value;
setting the voltage of the cathode with respect to the anode of the first avalanche diode in a range equal to or lower than a first value in a second period after the first period;
The sensor device, wherein the voltage of the cathode with respect to the anode of the first avalanche diode is set in a range above a first value for a third period of time after the second period of time.
8. A control method for controlling a first avalanche diode having an anode and a cathode by a control circuit, comprising:
By the control circuit,
in a first period, setting the voltage of the cathode to the anode of the first avalanche diode in a range above a first value;
setting the voltage of the cathode with respect to the anode of the first avalanche diode in a range equal to or lower than a first value in a second period after the first period;
A control method, wherein the voltage of the cathode with respect to the anode of the first avalanche diode is set in a range exceeding a first value in a third period after the second period.
9. A program for causing a computer to function as a control device for controlling a first avalanche diode having an anode and a cathode,
to the computer;
setting the voltage of the cathode to the anode of the first avalanche diode in a range above a first value in a first period;
setting the voltage of the cathode with respect to the anode of the first avalanche diode to a range equal to or less than a first value in a second period after the first period;
A program for setting the voltage of the cathode with respect to the anode of the first avalanche diode to a range greater than a first value during a third period after the second period.

10 sensor device 100 electromagnetic wave source 200 detection device 210 first avalanche diode (AD)
220 second avalanche diode (AD)
300 control device 310 control circuit 400 movable reflector 402 detection surface 402a first detection surface 402b second detection surface 410 splitter 412 terminal 412a terminal 412b terminal 414 terminal 414a terminal 414b terminal

Claims (18)

a control circuit for controlling a first avalanche diode having an anode and a cathode;
The control circuit is
in a first period, setting the voltage of the cathode to the anode of the first avalanche diode in a range above a first value;
setting the voltage of the cathode with respect to the anode of the first avalanche diode in a range equal to or lower than a first value in a second period after the first period;
setting the voltage of the cathode to the anode of the first avalanche diode in a range exceeding a first value in a third period after the second period;
gradually increasing the voltage of the cathode to the anode of the first avalanche diode over the first period;
The first period and the second period are continuous,
The control circuit adjusts the voltage of the cathode of the first avalanche diode with respect to the anode of the first avalanche diode after the electromagnetic wave is incident on the first avalanche diode in the first period from a value exceeding the first value to a value equal to or less than the first value. value and transition to the second period;
a current-voltage conversion circuit that converts a current flowing through the first avalanche diode into a voltage is connected to the first avalanche diode;
A comparator for comparing an output voltage of the current-voltage conversion circuit and a voltage of a power supply is connected to the current-voltage conversion circuit,
The comparator reduces the potential of the cathode of the first avalanche diode from a first potential according to the output of the comparator, thereby reducing the voltage of the cathode with respect to the anode of the first avalanche diode to a first value or less. A transistor is connected to switch to
The control circuit controls the first potential
Control device. a control circuit for controlling a first avalanche diode having an anode and a cathode;
The control circuit is
in a first period, setting the voltage of the cathode to the anode of the first avalanche diode in a range above a first value;
setting the voltage of the cathode with respect to the anode of the first avalanche diode in a range equal to or lower than a first value in a second period after the first period;
setting the voltage of the cathode to the anode of the first avalanche diode in a range exceeding a first value in a third period after the second period;
After the electromagnetic wave emitted from the electromagnetic wave source during the first period is incident on the first avalanche diode during the first period, the second period is entered;
transition from the second period to the third period so that the next electromagnetic wave is emitted from the electromagnetic wave source in the third period following the second period ;
The control circuit is connected to the electromagnetic wave source,
a current-voltage conversion circuit that converts a current flowing through the first avalanche diode into a voltage is connected to the first avalanche diode;
A comparator for comparing an output voltage of the current-voltage conversion circuit and a voltage of a power supply is connected to the current-voltage conversion circuit,
The comparator reduces the potential of the cathode of the first avalanche diode from a first potential according to the output of the comparator, thereby reducing the voltage of the cathode with respect to the anode of the first avalanche diode to a first value or less. A transistor is connected to switch to
The control circuit controls the first potential
Control device. a control circuit for controlling a first avalanche diode having an anode and a cathode;
The control circuit controls the anode of the first avalanche diode for a period from when the first electromagnetic wave emitted from the electromagnetic wave source is incident on the first avalanche diode to when the next second electromagnetic wave is emitted. setting the voltage of the cathode to a range equal to or less than a first value ;
The control circuit is connected to the electromagnetic wave source,
a current-voltage conversion circuit that converts a current flowing through the first avalanche diode into a voltage is connected to the first avalanche diode;
A comparator for comparing an output voltage of the current-voltage conversion circuit and a voltage of a power supply is connected to the current-voltage conversion circuit,
The comparator reduces the potential of the cathode of the first avalanche diode from a first potential according to the output of the comparator, thereby reducing the voltage of the cathode with respect to the anode of the first avalanche diode to a first value or less. A transistor is connected to switch to
The control device, wherein the control circuit controls the first potential . In the control device according to claim 3,
The control circuit is
During a first period from when the first electromagnetic wave is emitted until when the second electromagnetic wave is emitted, the voltage of the cathode with respect to the anode of the first avalanche diode exceeds the first value. set it to the range and
The control device, wherein the period after the first period is defined as the period from when the first electromagnetic wave is emitted until when the second electromagnetic wave is emitted. In the control device according to claim 3 or 4,
The control circuit is
in a third period following the period, setting the voltage of the cathode to the anode of the first avalanche diode in a range above a first value;
A control device that transitions from the period to the third period such that the second electromagnetic wave is emitted during the third period. In the control device according to claim 2,
The control device, wherein the control circuit gradually increases the voltage of the cathode with respect to the anode of the first avalanche diode during at least part of the first period. The control device according to claim 1,
The first avalanche diode is for detecting electromagnetic waves emitted from an electromagnetic wave source,
The control circuit is connected to the electromagnetic wave source,
The electromagnetic wave source emits one electromagnetic wave in the second period,
The control circuit switches the voltage of the cathode with respect to the anode of the first avalanche diode from a value equal to or less than the first value to a value greater than the first value after the electromagnetic wave source emits the one electromagnetic wave. A control device that transitions to the third period. The control device according to claim 1,
The first avalanche diode is for detecting electromagnetic waves emitted from an electromagnetic wave source,
The control circuit is connected to the electromagnetic wave source,
The electromagnetic wave source emits one electromagnetic wave in the second period,
The control circuit switches the voltage of the cathode with respect to the anode of the first avalanche diode from a value equal to or less than the first value to a value greater than the first value after the electromagnetic wave source emits the one electromagnetic wave. A control device that transitions to the third period. The control device according to claim 1,
the control circuit is also for controlling a second avalanche diode having an anode and a cathode;
The control circuit is
setting the voltage of the cathode with respect to the anode of the second avalanche diode to a range equal to or less than a second value in at least part of the first period;
setting the voltage of the cathode to the anode of the second avalanche diode in a range above a second value for at least part of the second period;
A controller for setting the voltage of the cathode with respect to the anode of the second avalanche diode to a range equal to or less than a second value during at least part of the third period. an electromagnetic source;
a first avalanche diode having an anode and a cathode for detecting electromagnetic waves emitted from the electromagnetic wave source;
a current-voltage conversion circuit connected to the first avalanche diode and converting a current flowing through the first avalanche diode into a voltage;
a comparator connected to the current-voltage conversion circuit for comparing the output voltage of the current-voltage conversion circuit with the voltage of the power supply;
connected to the comparator, and by lowering the potential of the cathode of the first avalanche diode from a first potential according to the output of the comparator, the voltage of the cathode with respect to the anode of the first avalanche diode is reduced to the first potential; a transistor that switches to a value of 1 or less;
a control circuit for controlling the first avalanche diode;
including
The control circuit is
in a first period, setting the voltage of the cathode to the anode of the first avalanche diode in a range above a first value;
setting the voltage of the cathode with respect to the anode of the first avalanche diode in a range equal to or lower than a first value in a second period after the first period;
setting the voltage of the cathode to the anode of the first avalanche diode in a range exceeding a first value in a third period after the second period;
gradually increasing the voltage of the cathode to the anode of the first avalanche diode over the first period;
The first period and the second period are continuous,
The control circuit is
controlling the first potential;
After the electromagnetic wave is incident on the first avalanche diode in the first period, the voltage of the cathode with respect to the anode of the first avalanche diode is switched from a value exceeding the first value to a value equal to or less than the first value, and the A sensor device that transitions to a second period . an electromagnetic source;
a first avalanche diode having an anode and a cathode for detecting electromagnetic waves emitted from the electromagnetic wave source;
a current-voltage conversion circuit connected to the first avalanche diode and converting a current flowing through the first avalanche diode into a voltage;
a comparator connected to the current-voltage conversion circuit for comparing the output voltage of the current-voltage conversion circuit with the voltage of the power supply;
connected to the comparator, and by lowering the potential of the cathode of the first avalanche diode from a first potential according to the output of the comparator, the voltage of the cathode with respect to the anode of the first avalanche diode is reduced to the first potential; a transistor that switches to a value of 1 or less;
a control circuit for controlling the first avalanche diode;
including
The control circuit is
controlling the first potential;
in a first period, setting the voltage of the cathode to the anode of the first avalanche diode in a range above a first value;
setting the voltage of the cathode with respect to the anode of the first avalanche diode in a range equal to or lower than a first value in a second period after the first period;
setting the voltage of the cathode to the anode of the first avalanche diode in a range exceeding a first value in a third period after the second period;
After the electromagnetic wave emitted from the electromagnetic wave source during the first period is incident on the first avalanche diode during the first period, the second period is entered;
The sensor device transitions from the second period to the third period such that the next electromagnetic wave is emitted from the electromagnetic wave source during the third period following the second period. an electromagnetic source;
a first avalanche diode having an anode and a cathode for detecting electromagnetic waves emitted from the electromagnetic wave source;
a current-voltage conversion circuit connected to the first avalanche diode and converting a current flowing through the first avalanche diode into a voltage;
a comparator connected to the current-voltage conversion circuit for comparing the output voltage of the current-voltage conversion circuit with the voltage of the power supply;
connected to the comparator, and by lowering the potential of the cathode of the first avalanche diode from a first potential according to the output of the comparator, the voltage of the cathode with respect to the anode of the first avalanche diode is reduced to the first potential; a transistor that switches to a value of 1 or less;
a control circuit for controlling the first avalanche diode;
including
The control circuit controls the anode of the first avalanche diode for a period from when the first electromagnetic wave emitted from the electromagnetic wave source is incident on the first avalanche diode to when the next second electromagnetic wave is emitted. setting the voltage of the cathode to a range equal to or less than a first value ;
The sensor device , wherein the control circuit controls the first potential . A control method for controlling a first avalanche diode having an anode and a cathode by a control circuit, comprising:
By the control circuit,
in a first period, setting the voltage of the cathode to the anode of the first avalanche diode in a range above a first value;
setting the voltage of the cathode with respect to the anode of the first avalanche diode in a range equal to or lower than a first value in a second period after the first period;
setting the voltage of the cathode to the anode of the first avalanche diode in a range exceeding a first value in a third period after the second period;
gradually increasing the voltage of the cathode to the anode of the first avalanche diode over the first period;
After the electromagnetic wave is incident on the first avalanche diode in the first period, the voltage of the cathode with respect to the anode of the first avalanche diode is switched from a value exceeding the first value to a value equal to or less than the first value, and the Move to the second period,
The first period and the second period are continuous,
a current-voltage conversion circuit that converts a current flowing through the first avalanche diode into a voltage is connected to the first avalanche diode;
A comparator for comparing an output voltage of the current-voltage conversion circuit and a voltage of a power supply is connected to the current-voltage conversion circuit,
The comparator reduces the potential of the cathode of the first avalanche diode from a first potential according to the output of the comparator, thereby reducing the voltage of the cathode with respect to the anode of the first avalanche diode to a first value or less. A transistor is connected to switch to
A control method , wherein the control circuit controls the first potential . A control method for controlling a first avalanche diode having an anode and a cathode by a control circuit, comprising:
By the control circuit,
in a first period, setting the voltage of the cathode to the anode of the first avalanche diode in a range above a first value;
setting the voltage of the cathode with respect to the anode of the first avalanche diode in a range equal to or lower than a first value in a second period after the first period;
setting the voltage of the cathode to the anode of the first avalanche diode in a range exceeding a first value in a third period after the second period;
After the electromagnetic wave emitted from the electromagnetic wave source during the first period is incident on the first avalanche diode during the first period, the second period is entered;
transition from the second period to the third period so that the next electromagnetic wave is emitted from the electromagnetic wave source in the third period following the second period ;
The control circuit is connected to the electromagnetic wave source,
a current-voltage conversion circuit that converts a current flowing through the first avalanche diode into a voltage is connected to the first avalanche diode;
A comparator for comparing an output voltage of the current-voltage conversion circuit and a voltage of a power supply is connected to the current-voltage conversion circuit,
The comparator reduces the potential of the cathode of the first avalanche diode from a first potential according to the output of the comparator, thereby reducing the voltage of the cathode with respect to the anode of the first avalanche diode to a first value or less. A transistor is connected to switch to
A control method , wherein the control circuit controls the first potential . A control method for controlling a first avalanche diode having an anode and a cathode by a control circuit, comprising:
The control circuit controls the anode of the first avalanche diode during the period from when the first electromagnetic wave emitted from the electromagnetic wave source is incident on the first avalanche diode to when the next second electromagnetic wave is emitted. setting the voltage of the cathode to a range equal to or less than a first value ;
The control circuit is connected to the electromagnetic wave source,
a current-voltage conversion circuit that converts a current flowing through the first avalanche diode into a voltage is connected to the first avalanche diode;
A comparator for comparing an output voltage of the current-voltage conversion circuit and a voltage of a power supply is connected to the current-voltage conversion circuit,
The comparator reduces the potential of the cathode of the first avalanche diode from a first potential according to the output of the comparator, thereby reducing the voltage of the cathode with respect to the anode of the first avalanche diode to a first value or less. A transistor is connected to switch to
A control method for controlling the first potential by the control circuit . A program for causing a computer to function as a control device for controlling a first avalanche diode having an anode and a cathode,
to the computer;
setting the voltage of the cathode to the anode of the first avalanche diode in a range above a first value in a first period;
setting the voltage of the cathode with respect to the anode of the first avalanche diode to a range equal to or less than a first value in a second period after the first period;
setting the voltage of the cathode with respect to the anode of the first avalanche diode in a range exceeding a first value in a third period after the second period;
gradually increasing the voltage of the cathode to the anode of the first avalanche diode over the first period;
After the electromagnetic wave is incident on the first avalanche diode in the first period, the voltage of the cathode with respect to the anode of the first avalanche diode is switched from a value exceeding the first value to a value equal to or less than the first value, and the Move to the second period,
The first period and the second period are continuous,
a current-voltage conversion circuit that converts a current flowing through the first avalanche diode into a voltage is connected to the first avalanche diode;
A comparator for comparing an output voltage of the current-voltage conversion circuit and a voltage of a power supply is connected to the current-voltage conversion circuit,
The comparator reduces the potential of the cathode of the first avalanche diode from a first potential according to the output of the comparator, thereby reducing the voltage of the cathode with respect to the anode of the first avalanche diode to a first value or less. A transistor is connected to switch to
A program that causes the computer to control the first potential . A program for causing a computer to function as a control device for controlling a first avalanche diode having an anode and a cathode,
to the computer;
setting the voltage of the cathode to the anode of the first avalanche diode in a range above a first value in a first period;
setting the voltage of the cathode with respect to the anode of the first avalanche diode to a range equal to or less than a first value in a second period after the first period;
setting the voltage of the cathode with respect to the anode of the first avalanche diode in a range exceeding a first value in a third period after the second period;
After the electromagnetic wave emitted from the electromagnetic wave source during the first period is incident on the first avalanche diode during the first period, the period is shifted to the second period;
shifting from the second period to the third period so that the next electromagnetic wave is emitted from the electromagnetic wave source in the third period following the second period ;
The control device is connected to the electromagnetic wave source,
a current-voltage conversion circuit that converts a current flowing through the first avalanche diode into a voltage is connected to the first avalanche diode;
A comparator for comparing an output voltage of the current-voltage conversion circuit and a voltage of a power supply is connected to the current-voltage conversion circuit,
The comparator reduces the potential of the cathode of the first avalanche diode from a first potential according to the output of the comparator, thereby reducing the voltage of the cathode with respect to the anode of the first avalanche diode to a first value or less. A transistor is connected to switch to
A program that causes the computer to control the first potential . A program for causing a computer to function as a control device for controlling a first avalanche diode having an anode and a cathode,
to the computer;
During the period from when the first electromagnetic wave emitted from the electromagnetic wave source is incident on the first avalanche diode to when the next second electromagnetic wave is emitted, the voltage of the cathode with respect to the anode of the first avalanche diode is Set it to the range below the first value ,
The control device is connected to the electromagnetic wave source,
a current-voltage conversion circuit that converts a current flowing through the first avalanche diode into a voltage is connected to the first avalanche diode;
A comparator for comparing an output voltage of the current-voltage conversion circuit and a voltage of a power supply is connected to the current-voltage conversion circuit,
The comparator reduces the potential of the cathode of the first avalanche diode from a first potential according to the output of the comparator, thereby reducing the voltage of the cathode with respect to the anode of the first avalanche diode to a first value or less. A transistor is connected to switch to
A program that causes the computer to control the first potential .

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