Object detection device

Abstract

To provide an object detection device capable of appropriately correcting the state switching timing of a light receiving unit.SOLUTION: An object detection device that detects the passage of an object on the basis of the interruption of infrared light projected from a light-projecting unit to a light-receiving unit includes a light-receiving control unit that controls the light-receiving unit, the light-receiving unit is switchable between a first state in which light projected by the light-projecting unit can be detected and a second state in which light projected by the light-projecting unit cannot be detected, the light-receiving control unit is configured to alternately switch the state of the light-receiving unit between the first state and the second state in synchronization with the light-projecting timing of the light-projecting unit, and includes an acquisition unit that acquires a waveform that indicates the progress of the intensity of light received by the light-receiving unit, and the light-receiving control unit corrects the state switching timing, which is the timing of switching between the first state and the second state, on the basis of the waveform.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an object detection device. [Background technology]

[0002] An object detection device is already known, for example, as described in Patent Document 1. This object detection device (referred to as a "photoelectric switch" in Patent Document 1) is equipped with a light-projecting unit and a light-receiving unit. This object detection device detects the passage of an object (the presence of an object) based on the interruption of infrared light projected from the light-projecting unit to the light-receiving unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5865669 Summary of the Invention [Problem to be solved by the invention]

[0004] In an object detection device as described above, it is conceivable that the light receiving unit can be switched between a first state in which it can detect light emitted by the light projecting unit, and a second state in which it cannot detect light emitted by the light projecting unit, and that a light receiving control unit that controls the light receiving unit can be configured to alternately switch the state of the light receiving unit between the first state and the second state in synchronization with the timing of light emission from the light projecting unit.

[0005] In this configuration, if a time discrepancy occurs between the timing unit on the light-projecting side (e.g., a crystal oscillator) and the timing unit on the light-receiving side, light may be projected at a timing when the light-receiving unit is in the second state. In that case, it will be determined that the infrared light projection has been blocked, even though in fact the infrared light projection has not been blocked.

[0006] Here, it is conceivable to configure the device so that the state switching timing, which is the timing of switching between the first state and the second state, is corrected based on the timing of receiving infrared light by the light receiving unit. However, in such a configuration, it is expected that erroneous correction will be performed if the light receiving unit receives infrared light from the outside (for example, infrared light from another object detection device).

[0007] An object of the present invention is to provide an object detection device capable of appropriately correcting the state switching timing of a light receiving unit. [Means for solving the problem]

[0008] A feature of the present invention is an object detection device comprising a light-projecting unit that projects infrared rays and a light-receiving unit that receives the infrared rays projected from the light-projecting unit, and which detects the passage of an object based on the interruption of the infrared rays projected from the light-projecting unit to the light-receiving unit, the object detection device further comprising a light-receiving control unit that controls the light-receiving unit, the light-receiving unit being switchable between a first state in which the light projected by the light-projecting unit can be detected and a second state in which the light projected by the light-projecting unit cannot be detected, the light-receiving control unit being configured to alternately switch the state of the light-receiving unit between the first state and the second state in synchronization with the light-projection timing of the light-projecting unit, and an acquisition unit that acquires a waveform that indicates a transition in the intensity of the light received by the light-receiving unit, and the light-receiving control unit corrects the state switching timing, which is the timing of switching between the first state and the second state, based on the waveform.

[0009] According to this configuration, the state switching timing of the light receiving unit is corrected based on a waveform that indicates a transition in the intensity of light received by the light receiving unit. As a result, when the light receiving unit receives infrared light from the outside (for example, infrared light from another object detection device), not only a peak (a mountain-shaped part including a maximum value) corresponding to the infrared light from the outside appears in the waveform, but also a peak corresponding to the infrared light projected from the light projecting unit. Then, by correcting the state switching timing of the light receiving unit based on the peak corresponding to the infrared light projected from the light projecting unit, the correction can be performed appropriately.

[0010] That is, according to this configuration, it is possible to realize an object detection device capable of appropriately correcting the state switching timing of the light receiving unit.

[0011] Furthermore, in the present invention, it is preferable that the light reception control section corrects the state switching timing based on maximum value information which is information indicating at least one of the magnitude and timing of a maximum value in the waveform.

[0012] According to this configuration, when multiple peaks appear in the waveform, the maximum value information can be used to easily identify the peak corresponding to the infrared ray projected from the light-projecting unit, which makes it easy to appropriately correct the state switching timing of the light-receiving unit.

[0013] Furthermore, in the present invention, when a plurality of maximum values ​​are present during a first state period in which the light receiving unit is in the first state, it is preferable that the light receiving control unit corrects the state switching timing based on the maximum value information corresponding to the maximum value that has the smallest deviation from the maximum value in the previous first state period in terms of at least one of the magnitude and timing of the plurality of maximum values.

[0014] According to this configuration, it is easy to accurately identify the maximum value corresponding to the infrared ray projected from the light projecting unit, which makes it easy to appropriately correct the state switching timing of the light receiving unit.

[0015] Furthermore, in the present invention, it is preferable that the device further includes a first judgment unit which judges whether or not the waveform satisfies a predetermined first condition, the first condition being that the timing of the maximum value in a first state period during which the light receiving unit is in the first state is earlier than the timing of the maximum value in the first state period before the previous time, the light receiving control unit corrects the state switching timing to be earlier when a predetermined second condition is satisfied, the second condition being that the first condition is satisfied consecutively over a predetermined number of first state periods, and the light receiving control unit does not correct the state switching timing when the first condition is satisfied but the second condition is not satisfied.

[0016] According to this configuration, when the light projection timing is relatively advanced, the state switching timing is corrected to be advanced, which makes it easier to appropriately correct the state switching timing of the light receiving unit.

[0017] Furthermore, in the present invention, it is preferable that the device further includes a second judgment unit which judges whether or not the waveform satisfies a predetermined third condition, the third condition being that the timing of the maximum value in a first state period during which the light receiving unit is in the first state is later than the timing of the maximum value in the first state period before the previous time, the light receiving control unit corrects the state switching timing to be delayed when a predetermined fourth condition is satisfied, the fourth condition being that the third condition is satisfied continuously over a predetermined number of first state periods, and the light receiving control unit does not correct the state switching timing when the third condition is satisfied but the fourth condition is not satisfied.

[0018] According to this configuration, when the light projection timing is relatively delayed, the state switching timing is corrected to be delayed, which makes it easier to appropriately correct the state switching timing of the light receiving unit.

[0019] Furthermore, in the present invention, it is preferable to provide a correction memory unit that stores correction information, which is information regarding the correction, when the state switching timing is corrected, and a prediction unit that predicts the time when the state switching timing will next be corrected based on the correction information.

[0020] According to this configuration, the state switching timing can be corrected based on the prediction result by the prediction unit, for example, which makes it easier to appropriately correct the state switching timing of the light receiving unit.

[0021] Furthermore, in the present invention, it is preferable that the light receiving control unit corrects the state switching timing based on the maximum value information corresponding to the maximum value in a first state period, which is a period during which the light receiving unit is in the first state, and not based on the maximum value information corresponding to the maximum value in any period other than the first state period.

[0022] In the waveform, the maximum values ​​outside the first state period are likely to be maximum values ​​corresponding to infrared rays from outside. In other words, with this configuration, it is possible to correct the state switching timing after excluding the maximum values ​​likely to be corresponding to infrared rays from outside from the objects of consideration (in other words, information referenced for correcting the state switching timing). This makes it easier to appropriately correct the state switching timing of the light receiving unit. [Brief description of the drawings]

[0023] [Figure 1] FIG. 2 is a front view showing the configuration of the object detection device. [Diagram 2] FIG. 1 is a block diagram showing a configuration of an object detection device. [Diagram 3] 4 is a diagram showing transitions in the intensity (output level) of infrared light projected from each light-projecting unit and transitions in the state of each light-receiving unit. FIG. [Figure 4] 4A to 4C are diagrams showing transitions in the intensity (input level) of received light at a light receiving section and transitions in the state of the light receiving section. [Diagram 5] FIG. 4 is a block diagram showing a configuration of an object detection device according to a first alternative embodiment. [Figure 6] 13A and 13B are diagrams illustrating an example in which a correction is performed to advance the state switching timing in the first alternative embodiment. [Figure 7] 13A and 13B are diagrams illustrating an example in which correction for advancing the state switching timing is not performed in the first alternative embodiment. [Figure 8] 13A and 13B are diagrams illustrating an example in which a correction is performed to delay the state switching timing in the first alternative embodiment. [Figure 9] 13A and 13B are diagrams illustrating an example in which correction for delaying the state switching timing is not performed in the first alternative embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the accompanying drawings. In the following description, unless otherwise specified, the direction of the arrow U in the drawings is "up" and the direction of the arrow D is "down."

[0025] [Configuration of the object detection device] As shown in Fig. 1, the object detection device 1 includes a light projecting unit 2 and a light receiving unit 3. The light projecting unit 2 and the light receiving unit 3 are installed in a state spaced apart from each other.

[0026] The light-projecting unit 2 projects infrared rays 4. The light-receiving unit 3 receives the infrared rays 4 projected from the light-projecting unit 2.

[0027] The object detection device 1 includes a plurality of light projecting and receiving mechanisms 6. More specifically, the object detection device 1 includes a first mechanism 11 and a second mechanism 12. Both the first mechanism 11 and the second mechanism 12 are the light projecting and receiving mechanisms 6.

[0028] The first mechanism 11 is located at the upper part of the object detection device 1. The second mechanism 12 is located at the lower part of the object detection device 1. In this manner, the multiple light emitting and receiving mechanisms 6 are lined up in the vertical direction.

[0029] In this embodiment, the object detection device 1 includes two light emitting and receiving mechanisms 6, one above the other. However, the present invention is not limited to this. The object detection device 1 may include any number of light emitting and receiving mechanisms 6.

[0030] Each light projecting and receiving mechanism 6 has a light projecting unit 7 and a light receiving unit 8. The light projecting unit 7 projects infrared rays 4. The light receiving unit 8 receives the infrared rays 4 projected from the light projecting unit 7. In other words, the object detection device 1 includes the light projecting unit 7 that projects infrared rays 4, and the light receiving unit 8 that receives the infrared rays 4 projected from the light projecting unit 7. The object detection device 1 detects the passage of an object based on the interruption of the projection of the infrared rays 4 from the light projecting unit 7 to the light receiving unit 8.

[0031] The object whose passage is detected is not particularly limited, but may be, for example, an intruder.

[0032] As shown in FIG. 1, the first mechanism 11 has an upper-stage light-projecting unit 71 and an upper-stage light-receiving unit 81. The upper-stage light-projecting unit 71 and the upper-stage light-receiving unit 81 face each other. The upper-stage light-projecting unit 71 is a light-projecting unit 7. The upper-stage light-receiving unit 81 is a light-receiving unit 8 corresponding to the upper-stage light-projecting unit 71. In other words, the upper-stage light-projecting unit 71 projects infrared rays 4 toward the upper-stage light-receiving unit 81. Then, the upper-stage light-receiving unit 81 receives the infrared rays 4 projected from the upper-stage light-projecting unit 71.

[0033] The second mechanism 12 has a lower-stage light-projecting unit 72 and a lower-stage light-receiving unit 82. The lower-stage light-projecting unit 72 and the lower-stage light-receiving unit 82 face each other. The lower-stage light-projecting unit 72 is a light-projecting unit 7. The lower-stage light-receiving unit 82 is a light-receiving unit 8 corresponding to the lower-stage light-projecting unit 72. In other words, the lower-stage light-projecting unit 72 projects infrared rays 4 toward the lower-stage light-receiving unit 82. And the lower-stage light-receiving unit 82 receives the infrared rays 4 projected from the lower-stage light-projecting unit 72.

[0034] The upper light-projecting section 71 and the lower light-projecting section 72 are included in a light-projecting unit 2. The upper light-receiving section 81 and the lower light-receiving section 82 are included in a light-receiving unit 3.

[0035] The light-projecting unit 2 has a light-projecting body 21 and a light-projecting cover 22. An upper light-projecting section 71 and a lower light-projecting section 72 are provided on the light-projecting body 21. The light-projecting cover 22 is made of resin and configured to cover the upper light-projecting section 71 and the lower light-projecting section 72. The light-projecting cover 22 is detachable from the light-projecting body 21. Infrared rays 4 pass through the light-projecting cover 22.

[0036] The light-receiving unit 3 has a light-receiving main body 31 and a light-receiving cover 32. An upper light-receiving section 81 and a lower light-receiving section 82 are provided on the light-receiving main body 31. The light-receiving cover 32 is made of resin and is configured to cover the upper light-receiving section 81 and the lower light-receiving section 82. The light-receiving cover 32 is detachable from the light-receiving main body 31. Infrared rays 4 pass through the light-receiving cover 32.

[0037] [Control of the light projecting unit and the light receiving unit] 2, the light-projecting unit 2 (more specifically, the light-projecting main body 21) has a light-projection control section 23. The light-projection control section 23 controls each of the light-projecting sections 7 (more specifically, the upper light-projecting section 71 and the lower light-projecting section 72).

[0038] The light-projection control unit 23 controls each light-projecting unit 7 so as to project light as shown in Fig. 3. More specifically, in Fig. 3, the "upper light projection" indicates a transition in the intensity (output level) of the infrared rays 4 projected from the upper light-projecting unit 71. The "lower light projection" indicates a transition in the intensity (output level) of the infrared rays 4 projected from the lower light-projecting unit 72 in the first mode.

[0039] The light-projection control unit 23 controls each light-projection unit 7 so that the intensity (output level) of the infrared rays 4 projected from each light-projection unit 7 becomes pulsed as shown in the "upper light-projection stage" and "lower light-projection stage" of Fig. 3. In this specification, one pulse is considered to be one light projection.

[0040] 3, the light-projection control unit 23 controls each light-projecting unit 7 so that light projection in the light-projecting and receiving mechanism 6 is performed while avoiding the timing of light projection in other light-projecting and receiving mechanisms 6. More specifically, the light-projection control unit 23 controls the upper-stage light-projecting unit 71 and the lower-stage light-projecting unit 72 so that the light-projection timing of the upper-stage light-projecting unit 71 and the light-projection timing of the lower-stage light-projecting unit 72 do not coincide (do not overlap).

[0041] 3, in this embodiment, light projection by the upper light projector 71 and light projection by the lower light projector 72 are performed alternately. The light projection period by the lower light projector 72 is alternately switched between a first period T1 and a second period T2. The light projection period by the upper light projector 71 is maintained as a third period T3.

[0042] 2, the light receiving unit 3 (more specifically, the light receiving main body 31) has a light receiving control section 33. The light receiving control section 33 controls each light receiving section 8 (more specifically, the upper light receiving section 81 and the lower light receiving section 82). That is, the object detection device 1 has the light receiving control section 33 that controls the light receiving sections 8.

[0043] The light receiving control unit 33 can switch the state of each light receiving unit 8 between a first state and a second state. The first state is a state in which light emitted by the light projector 7 can be detected. The second state is a state in which light emitted by the light projector 7 cannot be detected. In other words, the light receiving unit 8 can be switched between the first state in which the light emitted by the light projector 7 can be detected, and the second state in which the light emitted by the light projector 7 cannot be detected.

[0044] More specifically, in Fig. 3, the transition of the state of the upper light receiving section 81 is shown as the "upper light receiving section". Also, the transition of the state of the lower light receiving section 82 is shown as the "lower light receiving section". In the graphs of the "upper light receiving section" and the "lower light receiving section" in Fig. 3, "ON" corresponds to the first state, and "OFF" corresponds to the second state.

[0045] As shown in FIG. 3, the upper light receiving section 81 goes into a first state so as to coincide with the light projection timing of the upper light projecting section 71, and goes into a second state when the upper light projecting section 71 is not projecting light.

[0046] The lower light receiving section 82 goes into the first state so as to coincide with the light projection timing of the lower light projecting section 72, and goes into the second state when the lower light projecting section 72 is not projecting light.

[0047] In this manner, the light-receiving control section 33 is configured to alternately switch the state of the light-receiving section 8 between the first state and the second state in synchronization with the light-projecting timing of the light-projecting section 7.

[0048] [About synchronization] The control for synchronizing the state switching of the light receiving unit 8 with the light projection timing of the light projecting unit 7 will be described in detail below.

[0049] In this embodiment, it is assumed that not only the infrared rays 4 from the upper light-projecting unit 71 but also the infrared rays 4 projected from the lower light-projecting unit 72 and spreading out in a fan shape reach the upper light-receiving unit 81. It is assumed that not only the infrared rays 4 from the lower light-projecting unit 72 but also the infrared rays 4 projected from the upper light-projecting unit 71 and spreading out in a fan shape reach the lower light-receiving unit 82.

[0050] The light-receiving control unit 33 is configured to be able to execute synchronous start control. The synchronous start control is control that starts state switching of each light-receiving unit 8 synchronized with the light-projection timing of each light-projecting unit 7. In other words, the synchronous start control is control that starts synchronization between the light-projection timing of each light-projecting unit 7 and the state switching of each light-receiving unit 8. The synchronous start control may be executed, for example, when the operation of the object detection device 1 is started.

[0051] 2, in the synchronization start control, the light-receiving control unit 33 acquires from the upper light-receiving unit 81 the detection result of the infrared rays 4 received by the upper light-receiving unit 81. At this time, the upper light-receiving unit 81 receives not only the infrared rays 4 from the upper light-projecting unit 71 but also the infrared rays 4 from the lower light-projecting unit 72.

[0052] Based on the detection result, the light-reception control unit 33 identifies the infrared ray 4 (pulse) whose light-reception cycle is the third cycle T3. As a result, the light-reception control unit 33 identifies the infrared ray 4 as the infrared ray 4 projected from the upper-stage light-projection unit 71. Then, the light-reception control unit 33 starts switching the state of the upper-stage light-receiving unit 81 so as to synchronize with the light-receiving cycle of the infrared ray 4. As a result, the state switching of the upper-stage light-receiving unit 81 is synchronized with the light-projection timing of the upper-stage light-projection unit 71.

[0053] 2, in the synchronization start control, the light-reception control unit 33 acquires, from the lower light-receiving unit 82, the detection result of the infrared rays 4 received by the lower light-receiving unit 82. At this time, the lower light-receiving unit 82 receives not only the infrared rays 4 from the lower light-projecting unit 72, but also the infrared rays 4 from the upper light-projecting unit 71.

[0054] Based on the detection result, the light-reception control unit 33 identifies the infrared ray 4 (pulse) whose light-reception cycle alternates between a first cycle T1 and a second cycle T2. As a result, the light-reception control unit 33 identifies the infrared ray 4 as the infrared ray 4 projected from the lower-stage light-projecting unit 72. Then, the light-reception control unit 33 starts switching the state of the lower-stage light-receiving unit 82 so as to synchronize with the light-receiving cycle of the infrared ray 4. As a result, the state switching of the lower-stage light-receiving unit 82 is synchronized with the light-projecting timing of the lower-stage light-projecting unit 72.

[0055] In addition, in the synchronization start control, the upper light receiving section 81 and the lower light receiving section 82 may always be in the first state until the state switching of each light receiving section 8 synchronized with the light projection timing of each light projecting section 7 starts.

[0056] When state switching of the upper stage light receiving section 81 synchronized with the light projection timing of the upper stage light projecting section 71 and state switching of the lower stage light receiving section 82 synchronized with the light projection timing of the lower stage light projecting section 72 are started, the synchronization start control ends.

[0057] [Report] 2, the light-receiving unit 3 has an alarm unit 35. The alarm unit 35 acquires, from the upper light-receiving unit 81, a detection result of the infrared rays 4 (light projected by the light-projecting unit 7) received by the upper light-receiving unit 81. The alarm unit 35 also acquires, from the lower light-receiving unit 82, a detection result of the infrared rays 4 (light projected by the light-projecting unit 7) received by the lower light-receiving unit 82.

[0058] The alarm unit 35 issues an alarm based on the detection result of the infrared rays 4 (light emitted by the light-emitting unit 7) received by each light-receiving unit 8 (in other words, the upper light-receiving unit 81 and the lower light-receiving unit 82). In this embodiment, the alarm issued by the alarm unit 35 is the output of an alarm signal to an alarm device (not shown). Upon receiving the alarm signal, the alarm device issues an alarm by sound, light, etc. that the passage of an object has been detected. The alarm device may or may not be included in the object detection device 1.

[0059] In this embodiment, when the projection of the infrared rays 4 is interrupted in at least one of the first mechanism 11 and the second mechanism 12, the alarm unit 35 issues an alarm. However, the present invention is not limited to this. When the projection of the infrared rays 4 is interrupted in both the first mechanism 11 and the second mechanism 12, the alarm unit 35 may also issue an alarm. In other words, when the projection of the infrared rays 4 is interrupted in only one of the first mechanism 11 and the second mechanism 12, the alarm unit 35 may not issue an alarm.

[0060] Alternatively, the object detection device 1 may have two operation modes, an AND mode and an OR mode. In this case, in the AND mode, an alarm may be issued only when the projection of the infrared rays 4 is interrupted in both the first mechanism 11 and the second mechanism 12. In the OR mode, an alarm may be issued when the projection of the infrared rays 4 is interrupted in at least one of the first mechanism 11 and the second mechanism 12. Although not particularly limited, for example, the operation mode may be set based on a manual operation of a setting switch (not shown).

[0061] [Correction of state switching timing] 2, the light-receiving control unit 33 has an acquisition unit 36 ​​and a timing correction unit 37. The acquisition unit 36 ​​acquires a waveform (see FIG. 4) indicating a transition in the intensity of light received by each light-receiving unit 8. The timing correction unit 37 corrects the state switching timing of each light-receiving unit 8 based on the waveform. The state switching timing is the timing of switching between the first state and the second state.

[0062] That is, the object detection device 1 includes an acquisition unit 36 ​​that acquires a waveform that indicates a transition in the intensity of received light at the light receiving unit 8. Furthermore, the light receiving control unit 33 corrects the state switching timing, which is the timing of switching between the first state and the second state, based on the waveform.

[0063] The correction of the state switching timing will be described in detail below.

[0064] 4 shows an example in which the state switching timing of the upper light receiving section 81 is corrected. The following description also applies to the correction of the state switching timing of the lower light receiving section 82.

[0065] The upper part of Fig. 4 shows a waveform indicating the transition of the intensity of received light at the upper light receiving section 81. The lower part of Fig. 4 shows the transition of the state of the upper light receiving section 81 as the "detection state". In the graph of the "detection state" in Fig. 4, "ON" corresponds to the first state, and "OFF" corresponds to the second state.

[0066] 2, the light receiving control unit 33 acquires, from the upper light receiving unit 81, a detection result of the infrared rays 4 received by the upper light receiving unit 81. The acquisition unit 36 ​​acquires a waveform indicating a transition in the intensity of the received light at the upper light receiving unit 81 based on the detection result. Although not particularly limited, the acquisition unit 36 ​​may acquire the waveform by, for example, performing A / D conversion on the detection result.

[0067] In this embodiment, the acquisition unit 36 ​​acquires the waveform regardless of the state of the upper light receiving unit 81. However, the present invention is not limited to this. The acquisition unit 36 ​​may acquire the waveform only during the period in which the upper light receiving unit 81 is in the first state. In other words, the waveform acquired by the acquisition unit 36 ​​may indicate the transition of the intensity of received light only during the period in which the upper light receiving unit 81 is in the first state.

[0068] 4 shows a first period E1, a second period E2, a third period E3, a fourth period E4, and a fifth period E5. The first period E1, the third period E3, and the fifth period E5 are all first state periods G1. The first state period G1 is a period during which the light receiving section 8 (the upper light receiving section 81 in the example shown in FIG. 4) is in the first state.

[0069] Although not particularly limited, in the present embodiment, the length of the first state period G1 is constant, that is, the lengths of the first period E1, the third period E3, and the fifth period E5 are the same.

[0070] The second period E2 and the fourth period E4 are both the second state period G2. The second state period G2 is a period in which the light receiving section 8 (the upper light receiving section 81 in the example shown in FIG. 4) is in the second state.

[0071] A central point CE is also shown in Fig. 4. The central point CE is the middle (center) point in the first state period G1.

[0072] FIG. 4 also shows a first peak P1, a second peak P2, a third peak P3, a fourth peak P4, a fifth peak P5, a first maximum value Q1, a second maximum value Q2, a third maximum value Q3, a fourth maximum value Q4, and a fifth maximum value Q5.

[0073] The first peak P1, the second peak P2, the third peak P3, the fourth peak P4, and the fifth peak P5 are all peaks (mountain-shaped parts including maximum values) that appear in the waveform acquired by the acquisition unit 36. The first maximum value Q1, the second maximum value Q2, the third maximum value Q3, the fourth maximum value Q4, and the fifth maximum value Q5 are the maximum values ​​in the first peak P1, the second peak P2, the third peak P3, the fourth peak P4, and the fifth peak P5, respectively.

[0074] The timing of the first maximum value Q1 belongs to the first period E1. In particular, the timing of the first maximum value Q1 coincides with the center point CE of the first period E1.

[0075] The timing of the second maximum value Q2 belongs to the second period E2.

[0076] The timings of the third maximum value Q3 and the fourth maximum value Q4 belong to the third period E3. The timing of the third maximum value Q3 is earlier than the center point CE of the third period E3 by the first time difference J1. The timing of the fourth maximum value Q4 is later than the center point CE of the fourth period E4 by the second time difference J2.

[0077] The timing of the fifth maximum value Q5 belongs to the fifth period E5. In particular, the timing of the fifth maximum value Q5 coincides with the center point CE of the fifth period E5.

[0078] The magnitudes of the first maximum value Q1, the third maximum value Q3, and the fifth maximum value Q5 are assumed to be the same. The magnitude of the second maximum value Q2 is assumed to be smaller than the magnitude of the third maximum value Q3. The magnitude of the fourth maximum value Q4 is assumed to be larger than the magnitude of the third maximum value Q3.

[0079] 2, the light receiving control unit 33 has a correction determination unit 38. The correction determination unit 38 determines whether or not it is necessary to correct the state switching timing of the light receiving unit 8, based on the waveform acquired by the acquisition unit 36. More specifically, the correction determination unit 38 determines whether or not it is necessary to correct the start timing of the next first state period G1, based on the portion of the waveform that corresponds to the first state period G1.

[0080] At this time, if there is a maximum value whose timing coincides (or nearly coincides) with the central point CE, the correction determination unit 38 determines that correction of the state switching timing of the light receiving unit 8 is not necessary (more specifically, determines that correction of the start timing of the next first state period G1 is not necessary).

[0081] Furthermore, if there is no maximum value whose timing coincides (or nearly coincides) with the central point CE, the correction determination unit 38 determines that the state switching timing of the light receiving unit 8 needs to be corrected (more specifically, determines that the start timing of the next first state period G1 needs to be corrected).

[0082] 4, there is a maximum value whose timing coincides with the central time point CE of the first period E1. Therefore, the correction determination unit 38 determines that it is not necessary to correct the start timing of the third period E3, which is the next first state period G1.

[0083] 4, there is no maximum value whose timing coincides with the central time point CE of the third period E3. Therefore, the correction determination unit 38 determines that it is necessary to correct the start timing of the fifth period E5, which is the next first state period G1.

[0084] If the correction determination unit 38 determines that the state switching timing of the light receiving unit 8 needs to be corrected (more specifically, if it determines that the start timing of the next first state period G1 needs to be corrected), the timing correction unit 37 corrects the state switching timing of the light receiving unit 8 (more specifically, corrects the start timing of the next first state period G1).

[0085] At this time, the timing corrector 37 corrects the state switching timing based on the maximum value information, which is information indicating at least one of the magnitude and timing of the maximum value in the waveform.

[0086] That is, the light reception control unit 33 corrects the state switching timing based on maximum value information, which is information indicating at least one of the magnitude and timing of the maximum value in the waveform.

[0087] More specifically, when correcting the state switching timing, the timing correction unit 37 first identifies all maximum values ​​in the waveform that belong to the first state period G1 (the third period E3 in the example shown in FIG. 4) and that do not include any maximum values ​​whose timing coincides with the central time point CE. As a result, in the example shown in FIG. 4, the third maximum value Q3 and the fourth maximum value Q4 are identified.

[0088] Next, the timing correction unit 37 acquires maximum value information corresponding to each identified maximum value based on the waveform. In this embodiment, the maximum value information acquired by the timing correction unit 37 is information indicating the timing of the maximum value. However, the present invention is not limited to this. The maximum value information acquired by the timing correction unit 37 may be information indicating the magnitude of the maximum value, or may be information indicating the magnitude and timing of the maximum value.

[0089] Then, the timing correction unit 37 corrects the state switching timing based on the acquired maximum value information. At this time, if there are multiple maximum values ​​in the first state period G1 (the third period E3 in the example shown in FIG. 4) in which there is no maximum value whose timing coincides with the central time point CE, the timing correction unit 37 determines that the maximum value among the multiple maximum values ​​that has the smallest deviation from the maximum value in the previous first state period G1 (the first period E1 in the example shown in FIG. 4) in at least one of the magnitude and timing is the light projection maximum value. Note that the light projection maximum value is the maximum value corresponding to the light projection from the light projector 7 (the upper light projector 71 in the example shown in FIG. 4) corresponding to the light receiver 8. Then, the timing correction unit 37 corrects the state switching timing based on the maximum value information corresponding to the light projection maximum value.

[0090] 4, the timing of the first maximum value Q1, which is the maximum value in the first period E1, coincides with the central time point CE. In contrast, the timing of the third maximum value Q3, which is one of the two maximum values ​​in the third period E3, is shifted from the central time point CE by a first time difference J1. Moreover, the timing of the fourth maximum value Q4, which is the other of the two maximum values ​​in the third period E3, is shifted from the central time point CE by a second time difference J2. The first time difference J1 is shorter than the second time difference J2. That is, in terms of timing, the shift of the third maximum value Q3 from the central time point CE is smaller than the shift of the fourth maximum value Q4 from the central time point CE.

[0091] Therefore, the timing correction unit 37 determines that the third maximum value Q3 is the light projection maximum value. In this way, the third maximum value Q3 is determined to be the light projection maximum value based on the "deviation from the maximum value in the previous first state period G1" regarding the timing of the maximum value.

[0092] Then, the timing correction unit 37 corrects the state switching timing based on the maximum value information corresponding to the third maximum value Q3. More specifically, the timing correction unit 37 corrects the start timing of the fifth period E5 to be earlier by the first time difference J1 based on the timing of the third maximum value Q3. As a result, the length of the fourth period E4 becomes shorter than before the correction.

[0093] In this way, the timing correction section 37 determines the magnitude of correction of the start timing of the first state period G1 based on the "deviation from the maximum value in the previous first state period G1" regarding the timing.

[0094] More specifically, the timing correction unit 37 determines the magnitude of correction of the start timing of the first state period G1 so as to be equal to the magnitude of "deviation from the maximum value in the previous first state period G1" with respect to timing. Furthermore, the timing correction unit 37 corrects the start timing of the first state period G1 in the same direction as the direction of "deviation from the maximum value in the previous first state period G1" with respect to timing.

[0095] Furthermore, when determining the "deviation from the maximum value in the previous first state period G1" in terms of timing, the relative timings within the first state period G1 to which each maximum value belongs are compared. For example, the relative timing of the first maximum value Q1 within the first period E1 is compared with the relative timing of the third maximum value Q3 within the third period E3. In this case, more specifically, the relative timing of the first maximum value Q1 with respect to the central time point CE of the first period E1 may be compared with the relative timing of the third maximum value Q3 with respect to the central time point CE of the third period E3.

[0096] That is, in the present invention, "timing of the maximum value" means the relative timing within the first state period G1 to which the maximum value belongs.

[0097] However, the present invention is not limited to the configuration described above. The "deviation from the maximum value in the previous first state period G1" may be determined with respect to the magnitude of the maximum value. In this case, for example, in the example shown in FIG. 4, the difference between the magnitude of the first maximum value Q1 and the magnitude of the third maximum value Q3 is smaller than the difference between the magnitude of the first maximum value Q1 and the magnitude of the fourth maximum value Q4. As a result, the timing correction unit 37 determines that the third maximum value Q3 is the light projection maximum value based on the "deviation from the maximum value in the previous first state period G1" with respect to the magnitude of the maximum value.

[0098] In this way, when multiple maximum values ​​are present during the first state period G1, which is the period during which the light receiving unit 8 is in the first state, the light receiving control unit 33 corrects the state switching timing based on the maximum value information corresponding to the maximum value that has the smallest deviation from the maximum value in the previous first state period G1 in terms of at least one of the magnitude and timing of the multiple maximum values.

[0099] Furthermore, if there is only one maximum value during the first state period G1 (the third period E3 in the example shown in Figure 4) in which there is no maximum value whose timing coincides with the central point CE, the timing correction unit 37 determines that the maximum value is the light projection maximum value.

[0100] 4, the timing of the third maximum value Q3 in the third period E3 is earlier than the timing of the first maximum value Q1 in the first period E1, so the start timing of the fifth period E5 is corrected to be earlier. If the timing of the third maximum value Q3 in the third period E3 was later than the timing of the first maximum value Q1 in the first period E1, the start timing of the fifth period E5 would be corrected to be later.

[0101] 4, the state switching timing is corrected based on maximum value information corresponding to the third maximum value Q3, and not based on maximum value information corresponding to the second maximum value Q2. In this way, the light-receiving control unit 33 corrects the state switching timing based on maximum value information corresponding to maximum values ​​in the first state period G1, which is the period during which the light-receiving unit 8 is in the first state, and not based on maximum value information corresponding to maximum values ​​in any period other than the first state period G1.

[0102] 4, the length of each second state period G2 after the fifth period E5 is the same as the second period E2. That is, after the correction of the state switching timing, the light reception control unit 33 controls the lengths of the first state period G1 and the second state period G2 in the same manner as before the correction of the state switching timing.

[0103] The state switching timing of each light receiving unit 8 may be corrected uniformly or individually. If there is no peak in the first state period G1, the correction determination unit 38 determines that the infrared ray 4 has been blocked and determines that the state switching timing of the light receiving unit 8 does not need to be corrected (more specifically, determines that the start timing of the next first state period G1 does not need to be corrected). In this case, the light receiving control unit 33 does not correct the state switching timing of each light receiving unit 8.

[0104] [Prediction of correction period] 2, the light reception control unit 33 has a correction storage unit 39 and a prediction unit 40. The correction storage unit 39 stores correction information when a correction of the state switching timing is performed. The correction information is information related to the correction of the state switching timing that has been performed. In other words, the object detection device 1 has the correction storage unit 39 that stores correction information, which is information related to the correction, when a correction of the state switching timing is performed.

[0105] Although not particularly limited, the correction information may be, for example, the date and time when the state switching timing was corrected.

[0106] The prediction unit 40 predicts the time when the state switching timing will be next corrected by the timing correction unit 37, based on the correction information stored in the correction storage unit 39. That is, the object detection device 1 includes the prediction unit 40 which predicts the time when the state switching timing will next be corrected, based on the correction information.

[0107] Although not particularly limited, the prediction unit 40 may be configured to predict the time when the state switching timing will be corrected next by utilizing a neural network trained using deep learning.

[0108] The correction determination unit 38 may determine whether or not correction of the state switching timing of the light receiving unit 8 is necessary, based on the waveform acquired by the acquisition unit 36 ​​and the prediction result by the prediction unit 40. Furthermore, the object detection device 1 may include a notification unit (not shown) that notifies the prediction result by the prediction unit 40.

[0109] The light projection control unit 23, the light reception control unit 33, the alarm issuing unit 35, the acquisition unit 36, the timing correction unit 37, the correction determination unit 38, the correction memory unit 39, and the prediction unit 40 may be physical devices such as a microcomputer, or may be functional units in software.

[0110] According to the configuration described above, the state switching timing of the light receiving unit 8 is corrected based on the waveform indicating the transition of the intensity of light received by the light receiving unit 8. As a result, when the light receiving unit 8 receives infrared rays 4 from the outside (for example, infrared rays 4 from another object detection device 1), not only a peak (a mountain-shaped part including a maximum value) corresponding to the infrared rays 4 from the outside appears in the waveform, but also a peak corresponding to the infrared rays 4 projected from the light projecting unit 7. Then, by correcting the state switching timing of the light receiving unit 8 based on the peak corresponding to the infrared rays 4 projected from the light projecting unit 7, the correction can be performed appropriately.

[0111] That is, according to the configuration described above, an object detection device 1 capable of appropriately correcting the state switching timing of the light receiving section 8 can be realized.

[0112] [First Alternative Embodiment] In the above embodiment, when there is a maximum value whose timing coincides (or nearly coincides) with the central point CE, the correction determination unit 38 determines that correction of the state switching timing of the light receiving unit 8 is not necessary (more specifically, determines that correction of the start timing of the next first state period G1 is not necessary).

[0113] Furthermore, if there is no maximum value whose timing coincides (or nearly coincides) with the central point CE, the correction determination unit 38 determines that the state switching timing of the light receiving unit 8 needs to be corrected (more specifically, determines that the start timing of the next first state period G1 needs to be corrected).

[0114] However, the present invention is not limited thereto. The following describes the first embodiment of the present invention, focusing on the differences from the above embodiment. The configuration other than the parts described below is the same as the above embodiment. Also, the same reference numerals are used for the same configuration as the above embodiment.

[0115] 5 is a block diagram showing the configuration of an object detection device 1 in a first alternative embodiment of the present invention. As shown in FIG. 5, a correction determination unit 38 in the object detection device 1 has a first determination unit 41.

[0116] The first determination unit 41 determines whether or not the waveform acquired by the acquisition unit 36 ​​satisfies a predetermined first condition. The first condition is that the timing of the maximum value in the first state period G1 is earlier than the timing of the maximum value in a specific first state period G1 before the previous one.

[0117] That is, the object detection device 1 includes a first determination unit 41 that determines whether or not the waveform satisfies a predetermined first condition. The first condition is that the timing of the maximum value in a first state period G1, during which the light receiving unit 8 is in the first state, is earlier than the timing of the maximum value in the first state period G1 before the previous time.

[0118] In this configuration, the correction determination unit 38 determines whether or not a predetermined second condition is satisfied based on the determination result by the first determination unit 41. The second condition is that the first condition is satisfied continuously over a predetermined number of first state periods G1.

[0119] In this first alternative embodiment, the predetermined number of times is three times. However, the present invention is not limited to this. The predetermined number of times may be one time or any number of times equal to or greater than two times.

[0120] If the second condition is satisfied, the timing correction unit 37 corrects the state switching timing to be earlier. If the first condition is satisfied but the second condition is not satisfied, the timing correction unit 37 does not correct the state switching timing.

[0121] That is, when the second predetermined condition is satisfied, the light reception control unit 33 corrects the state switching timing to be earlier. Also, when the first condition is satisfied but the second condition is not satisfied, the light reception control unit 33 does not correct the state switching timing.

[0122] 6 shows a waveform acquired by the acquisition unit 36, and a sixth period E6, a seventh period E7, an eighth period E8, a ninth period E9, and a tenth period E10. The sixth period E6, the seventh period E7, the eighth period E8, the ninth period E9, and the tenth period E10 are all first state periods G1. Each of the sixth period E6, the seventh period E7, the eighth period E8, the ninth period E9, and the tenth period E10 includes one maximum value.

[0123] The timing of the maximum value belonging to the sixth period E6 coincides with the central point CE.

[0124] The timing of each maximum value belonging to the seventh period E7, the eighth period E8, and the ninth period E9 is earlier than the central time point CE. That is, the timing of each maximum value in the seventh period E7, the eighth period E8, and the ninth period E9 is earlier than the timing of the maximum value in a specific first state period G1 (specifically, the sixth period E6) before the previous one. Therefore, the above-mentioned first condition is satisfied in each of the seventh period E7, the eighth period E8, and the ninth period E9. That is, the first condition is satisfied continuously over three first state periods G1.

[0125] Therefore, the correction determination section 38 determines that the second condition is satisfied. Then, the timing correction section 37 corrects the start timing of the tenth period E10 so as to be earlier.

[0126] 7 shows, for example, a waveform acquired by the acquiring unit 36, and an eleventh period E11, a twelfth period E12, a thirteenth period E13, a fourteenth period E14, and a fifteenth period E15. The eleventh period E11, the twelfth period E12, the thirteenth period E13, the fourteenth period E14, and the fifteenth period E15 are all first state periods G1. The eleventh period E11, the twelfth period E12, the thirteenth period E13, the fourteenth period E14, and the fifteenth period E15 each include one maximum value.

[0127] The timing of the maximum value belonging to the eleventh period E11 coincides with the central point CE.

[0128] The timing of each maximum value in the 12th period E12 and the 13th period E13 is earlier than the central time point CE. However, the timing of the maximum value in the 14th period E14 coincides with the central time point CE. Therefore, the first condition described above is satisfied in the 12th period E12 and the 13th period E13, but not in the 14th period E14.

[0129] Therefore, the correction determination unit 38 determines that the second condition is not satisfied. Therefore, the timing correction unit 37 does not correct the state switching timing. Therefore, unlike the tenth period E10 in Fig. 6, a correction is not performed to advance the start timing of the fifteenth period E15 in Fig. 7.

[0130] As shown in FIG. 5, the correction determination section 38 in the object detection device 1 has a second determination section 42.

[0131] The second determination section 42 determines whether or not the waveform acquired by the acquisition section 36 satisfies a predetermined third condition. The third condition is that the timing of the maximum value in the first state period G1 is later than the timing of the maximum value in a specific first state period G1 before the previous one.

[0132] That is, the object detection device 1 includes a second determination unit 42 that determines whether or not the waveform satisfies a predetermined third condition. The third condition is that the timing of the maximum value in a first state period G1, in which the light receiving unit 8 is in the first state, is later than the timing of the maximum value in the first state period G1 before the previous time.

[0133] In this configuration, the correction determination unit 38 determines whether or not a predetermined fourth condition is satisfied based on the determination result by the second determination unit 42. The fourth condition is that the third condition is satisfied continuously over a predetermined number of first state periods G1.

[0134] In this first alternative embodiment, the predetermined number of times is three times. However, the present invention is not limited to this. The predetermined number of times may be one time or any number of times equal to or greater than two times.

[0135] If the fourth condition is satisfied, the timing correction unit 37 corrects the state switching timing to delay it. If the third condition is satisfied but the fourth condition is not satisfied, the timing correction unit 37 does not correct the state switching timing.

[0136] That is, when the predetermined fourth condition is satisfied, the light-receiving control unit 33 corrects the state switching timing to delay it. Also, when the third condition is satisfied but the fourth condition is not satisfied, the light-receiving control unit 33 does not correct the state switching timing.

[0137] 8 shows a waveform acquired by the acquiring unit 36, and a 16th period E16, a 17th period E17, an 18th period E18, a 19th period E19, and a 20th period E20. The 16th period E16, the 17th period E17, the 18th period E18, the 19th period E19, and the 20th period E20 are all first state periods G1. The 16th period E16, the 17th period E17, the 18th period E18, the 19th period E19, and the 20th period E20 each include one maximum value.

[0138] The timing of the maximum value belonging to the sixteenth period E16 coincides with the central point CE.

[0139] The timing of each maximum value belonging to the 17th period E17, 18th period E18, and 19th period E19 is later than the central time point CE. That is, the timing of each maximum value in the 17th period E17, 18th period E18, and 19th period E19 is later than the timing of the maximum value in a specific first state period G1 (specifically, the 16th period E16) before the previous one. Therefore, the above-mentioned third condition is satisfied in all of the 17th period E17, 18th period E18, and 19th period E19. That is, the third condition is satisfied continuously over three first state periods G1.

[0140] Therefore, the correction determination section 38 determines that the fourth condition is satisfied. Then, the timing correction section 37 corrects the start timing of the twentieth period E20 so as to delay it.

[0141] 9 shows, for example, a waveform acquired by the acquiring unit 36, and a 21st period E21, a 22nd period E22, a 23rd period E23, a 24th period E24, and a 25th period E25. The 21st period E21, the 22nd period E22, the 23rd period E23, the 24th period E24, and the 25th period E25 are all first state periods G1. The 21st period E21, the 22nd period E22, the 23rd period E23, the 24th period E24, and the 25th period E25 each include one maximum value.

[0142] The timing of the maximum value belonging to the twenty-first period E21 coincides with the central point CE.

[0143] The timing of each maximum value in the 22nd period E22 and the 23rd period E23 is later than the central time point CE. However, the timing of the maximum value in the 24th period E24 coincides with the central time point CE. Therefore, the third condition described above is satisfied in the 22nd period E22 and the 23rd period E23, but not in the 24th period E24.

[0144] Therefore, the correction determination unit 38 determines that the fourth condition is not satisfied. Therefore, the timing correction unit 37 does not correct the state switching timing. Therefore, unlike the 20th period E20 in Fig. 8, a correction is not performed to delay the start timing of the 25th period E25 in Fig. 9.

[0145] Other embodiments (1) The number of light projecting units 7 included in the object detection device 1 may be one, or may be any number equal to or greater than two.

[0146] (2) The number of light receiving units 8 included in the object detection device 1 may be one, or may be any number equal to or greater than two.

[0147] (3) The light receiving control unit 33 may be configured to correct the state switching timing regardless of the maximum value in the waveform.

[0148] (4) The light reception control unit 33 may be configured to correct the state switching timing based on both the magnitude and timing of the maximum value in the waveform.

[0149] (5) When multiple maximum values ​​are present during the first state period G1, the light receiving control unit 33 may correct the state switching timing based on maximum value information corresponding to a maximum value selected from the multiple maximum values ​​based on information other than the “deviation from the maximum value in the previous first state period G1.”

[0150] (6) The correction storage unit 39 does not necessarily have to be provided.

[0151] (7) The prediction unit 40 does not necessarily have to be provided.

[0152] (8) The light reception control unit 33 may correct the state switching timing based on maximum value information corresponding to maximum values ​​in periods other than the first state period G1.

[0153] The configurations disclosed in the above-mentioned embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, unless a contradiction occurs. In addition, the embodiments disclosed in this specification are merely examples, and the present invention is not limited to these embodiments, and can be appropriately modified within the scope of the present invention. [Industrial Applicability]

[0154] The present invention can be used in an object detection device. [Explanation of symbols]

[0155] 1: Object detection device 4: Infrared 7: Light projection section 8: Light receiving part 33: Light receiving control unit 36: Acquisition part 39: Correction storage section 40: Prediction section 41:1st judgment part 42:Second judgment part G1: First state period

Claims

1. a light-projecting unit that projects infrared rays; a light receiving unit that receives the infrared light projected from the light projecting unit, An object detection device that detects passage of an object based on interruption of infrared light projected from the light projecting unit to the light receiving unit, A light receiving control unit that controls the light receiving unit, the light receiving unit is switchable between a first state in which the light emitted by the light projecting unit can be detected and a second state in which the light receiving unit cannot be detected, the light-reception control unit is configured to alternately switch a state of the light-receiving unit between the first state and the second state in synchronization with a light-projecting timing of the light-projecting unit, An acquisition unit that acquires a waveform indicating a transition of the intensity of the received light at the light receiving unit, The light receiving control unit corrects a state switching timing, which is the timing of switching between the first state and the second state, based on the waveform.

2. The object detection device according to claim 1 , wherein the light reception control unit corrects the state switching timing based on maximum value information that is information indicating at least one of the magnitude and timing of a maximum value in the waveform.

3. 3. The object detection device according to claim 2, wherein when a plurality of maximum values ​​are present during a first state period in which the light receiving unit is in the first state, the light receiving control unit corrects the state switching timing based on the maximum value information corresponding to the maximum value that has the smallest deviation from the maximum value in the previous first state period in terms of at least one of magnitude and timing among the plurality of maximum values.

4. a first determination unit that determines whether or not the waveform satisfies a predetermined first condition, the first condition is that a timing of the maximum value in a first state period during which the light receiving unit is in the first state is earlier than a timing of the maximum value in a previous or previous first state period; The light reception control unit corrects the state switching timing to be earlier when a predetermined second condition is satisfied, the second condition is that the first condition is satisfied continuously for a predetermined number of the first state periods, The object detection device according to claim 2 , wherein the light reception control unit does not correct the state switching timing when the first condition is satisfied but the second condition is not satisfied.

5. a second determination unit that determines whether or not the waveform satisfies a predetermined third condition; the third condition is that a timing of the maximum value in a first state period during which the light receiving unit is in the first state is later than a timing of the maximum value in a previous or previous first state period; the light reception control unit corrects the state switching timing so as to delay it when a predetermined fourth condition is satisfied; the fourth condition is that the third condition is satisfied continuously for a predetermined number of the first state periods, The object detection device according to claim 2 , wherein the light reception control unit does not correct the state switching timing when the third condition is satisfied but the fourth condition is not satisfied.

6. a correction storage unit that stores correction information, which is information regarding the correction, when the state switching timing is corrected; The object detection device according to claim 1 , further comprising: a prediction unit configured to predict a time when the state switching timing will be corrected next based on the correction information.

7. 4. The object detection device according to claim 2 or 3, wherein the light receiving control unit corrects the state switching timing based on the maximum value information corresponding to the maximum value in a first state period, which is a period during which the light receiving unit is in the first state, and without being based on the maximum value information corresponding to the maximum value in any period other than the first state period.

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