Object detection device and object detection system

Abstract

To provide an object detection device and an object detection system with which optical axis is adjustable with good accuracy, yet it is possible to save labor of optical axis adjustment work.SOLUTION: The object detection device includes a plurality of light projection-receiving mechanisms, and each light projection-receiving mechanism comprises a light projection unit and a light receiving unit. The control mode of the light projection control unit is switchable between a first mode for optical axis adjustment work of each light projection unit and each light receiving unit and a second mode for detecting passage of an object. When the control mode of the light projection control unit is the first mode, the light projection control unit controls each light projection unit so that a light projection pattern which is a pattern of light projection by the light projection unit is different for each light projection-receiving mechanism and light projection by a light projection-receiving mechanism is carried out avoiding the timing of light projection by the other light projection-receiving mechanisms.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

[0002] As described in Patent Document 1, an object detection device (referred to as an "infrared detection sensor" in Patent Document 1) equipped with two upper and lower light projecting and receiving mechanisms is known. Generally, in such an object detection device, each light projecting and receiving mechanism has a light projecting section that projects infrared rays, and a light receiving section that receives the infrared rays projected from the light projecting section. Then, the passage of an object is detected based on the interruption of the infrared rays projected from the light projecting section to the light receiving section. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4352167 Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, when an object detection device as described above is installed, adjustment of the optical axis of each light-projecting unit and each light-receiving unit is required before starting operation. In this object detection device, for example, if pulsed infrared rays are projected from the upper and lower light-projecting units, and the waveform of each pulse is the same between the upper and lower light-projecting units, and the light-projection patterns are the same (for example, the same period) between the upper and lower units, it is difficult to identify, based on the infrared rays received by the light-receiving unit, whether the infrared rays were projected from the upper or lower light-projecting unit.

[0005] In this case, when adjusting the optical axis, it is necessary to stop the light emission of the other (e.g., the lower) while adjusting the optical axis of one (e.g., the upper) of the two-stage light emitting and receiving mechanisms. In other words, it is not possible to adjust the optical axes of the two-stage light emitting and receiving mechanisms at the same time. This means that the adjustment of the optical axes requires a relatively large amount of effort.

[0006] An object of the present invention is to provide an object detection device and an object detection system that are capable of adjusting an optical axis with high precision while reducing the labor required for adjusting the optical axis. [Means for solving the problem]

[0007] A feature of the object detection device of the present invention is that it comprises a plurality of light-projecting and receiving mechanisms, each of which has 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 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, and further comprises a light-projection control unit that controls each of the light-projecting units, and the control mode of the light-projection control unit is switchable between a first mode for adjusting the optical axes of each of the light-projecting units and each of the light-receiving units and a second mode for detecting the passage of an object, and when the control mode of the light-projection control unit is in the first mode, the light-projection control unit controls each of the light-projecting units so that a light projection pattern, which is a pattern of light projection by the light-projecting units, is different for each of the light-projecting and receiving mechanisms, and so that light projection in each of the light-projecting and receiving mechanisms is performed to avoid the timing of light projection in the other light-projecting and receiving mechanisms.

[0008] According to this configuration, when the control mode of the light projection control unit is the first mode, the light projection / reception mechanism projects light while avoiding the timing of light projection by other light projection / reception mechanisms, thereby making it possible to avoid a situation in which the light projection timings of a plurality of light projection / reception mechanisms coincide with each other, thereby reducing the accuracy of adjustment of the optical axis.

[0009] Furthermore, according to this configuration, when the control mode of the light-projecting control unit is the first mode, the light-projecting pattern differs for each light-projecting and receiving mechanism. This makes it possible to identify which light-projecting and receiving mechanism's light-projecting unit the infrared ray was projected from, based on the infrared ray received by the light-receiving unit. Therefore, in the optical axis adjustment work, while adjusting the optical axis of one of the multiple light-projecting and receiving mechanisms, it is not necessary to stop light projection from the other light-projecting and receiving mechanisms. In other words, the optical axis adjustment work of the multiple light-projecting and receiving mechanisms can be performed simultaneously.

[0010] Therefore, according to this configuration, it is possible to realize an object detection device that is capable of adjusting the optical axis with high precision while reducing the labor required for adjusting the optical axis.

[0011] Furthermore, in the present invention, it is preferable that the device includes a first mechanism which is the light-projecting and receiving mechanism, and a second mechanism which is the light-projecting and receiving mechanism different from the first mechanism, wherein the light-projection period of the light-projecting unit in the first mechanism is the sum of a first time and a second time different from the first time, and the light-projection period of the light-projecting unit in the second mechanism is alternately switched between a first period and a second period, the first period being twice as long as the first time, and the second period being twice as long as the second time.

[0012] According to this configuration, it is possible to realize a configuration that prevents the timing of light projection from coinciding between the first mechanism and the second mechanism with a relatively simple configuration, thereby realizing an object detection device that can adjust the optical axis with high precision, despite having a relatively simple configuration.

[0013] Furthermore, in the present invention, it is preferable that the light-projection control unit is capable of executing a temporary pause control in which the interval between light projections by the light-projection unit is temporarily lengthened, and that the light-projection control unit executes the temporary pause control every time a predetermined first number of light projections is performed in the first mode, and executes the temporary pause control every time a predetermined second number of light projections is performed in the second mode, the first number of times and the second number of times being different from each other.

[0014] According to this configuration, it is possible to determine whether the control mode of the light projection control unit is the first mode or the second mode based on the infrared light received by the light receiving unit. Therefore, when a member other than the light projection control unit in the object detection device (for example, if a light reception control unit that controls the light receiving unit is provided, the light reception control unit, etc.) is configured to determine the control mode of the light projection control unit, there is no need to provide a dedicated member for outputting a signal indicating whether the control mode of the light projection control unit is the first mode or the second mode. This makes it easier to keep manufacturing costs down.

[0015] Furthermore, in the present invention, an AND mode and an OR mode are provided, and in the AND mode, an alarm is issued when infrared light projection is interrupted in all of the multiple light-projecting and receiving mechanisms, and in the OR mode, an alarm is issued when infrared light projection is interrupted in at least one of the multiple light-projecting and receiving mechanisms, and each of the light-receiving units is switchable between a first state in which the light projection from the light-projecting unit can be detected and a second state in which the light projection from the light-projecting unit cannot be detected, and when the control mode of the light-projection control unit is in the second mode, each of the light-receiving units is always in the first state in the AND mode, and in the OR mode, each of the light-receiving units alternately switches between the first state and the second state in synchronization with the light projection timing of the corresponding light-projecting unit.

[0016] According to this configuration, in the AND mode, if multiple light-projecting units are configured to project infrared rays simultaneously, the intensity of the infrared rays received by each light-receiving unit becomes relatively high. This improves the S / N ratio in the AND mode and makes it more resistant to false alarms caused by external noise and the like.

[0017] Furthermore, according to this configuration, in the OR mode, each light receiving unit alternates between the first state and the second state in synchronization with the light projection timing of the corresponding light projecting unit. This makes it possible to prevent each light receiving unit from detecting light projection by a light projecting unit other than the corresponding light projecting unit. This improves the accuracy of detecting the passage of an object in the OR mode.

[0018] Furthermore, in the present invention, it is preferable that the multiple light-projecting and receiving mechanisms are arranged in the vertical direction and comprise a light-projecting unit and a light-receiving unit installed at a distance from each other, and that each of the light-projecting sections is included in the light-projecting unit and each of the light-receiving sections is included in the light-receiving unit.

[0019] According to this configuration, the passage of an object can be detected by a plurality of light emitting and receiving mechanisms at different heights, which makes it easier to prevent an object from passing through the detection range of the object detection device without blocking the infrared rays.

[0020] A feature of the object detection system of the present invention is that, in an object detection system having a plurality of the above-mentioned object detection devices, when the control mode of the light-projection control unit is the first mode, the light-projection control unit is capable of controlling each of the light-projection units so that the light-projection pattern is different from those of the other object detection devices.

[0021] According to this configuration, when the control mode of the light-projection control unit is in the first mode, the light-projection pattern differs for each object detection device, making it possible to determine, based on the infrared light received by the light-receiving unit, whether the infrared light is infrared light projected by the object detection device to which the light-receiving unit belongs.

[0022] Therefore, during the optical axis adjustment work, while adjusting the optical axis of one of the multiple object detection devices, it is not necessary to stop light projection from the other object detection devices. In other words, the optical axis adjustment work of the multiple object detection devices can be performed simultaneously. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a plan view showing a configuration of an object detection system. [Diagram 2] FIG. 2 is a front view showing the configuration of the object detection device. [Diagram 3] FIG. 1 is a block diagram showing a configuration of an object detection device. [Figure 4] 4 is a diagram showing a transition of the intensity (output level) of infrared rays projected from each light-projecting unit. FIG. [Diagram 5] 5 is a diagram showing transitions in the intensity (output level) of infrared light projected from each light-projecting section and transitions in the state of each light-receiving section in the first mode. FIG. [Figure 6] 11 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 in AND mode. FIG. 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 Object Detection System] 1, the object detection system A in this embodiment includes a plurality of object detection devices 1. More specifically, the object detection system A in this embodiment includes four object detection devices 1. However, the present invention is not limited to this. The number of object detection devices 1 included in the object detection system A may be three or less, or may be five or more.

[0026] 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 spaced-apart state. That is, the object detection device 1 includes the light projecting unit 2 and the light receiving unit 3 which are installed in a spaced-apart state. Each object detection device 1 has the same configuration.

[0027] 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.

[0028] The multiple object detection devices 1 are arranged around a predetermined area 5 in a plan view. In the example shown in Fig. 1, the multiple object detection devices 1 are arranged such that the entire periphery (all four sides) of the predetermined area 5 is surrounded by multiple infrared rays 4 in a plan view. However, the present invention is not limited to this. The multiple object detection devices 1 may be arranged in any manner.

[0029] The predetermined area 5 is not particularly limited, and may be, for example, a restricted access area, a protected area, a building, or the like.

[0030] [Configuration of the object detection device] 2, 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 light projecting and receiving mechanisms 6. In other words, the object detection device 1 includes the first mechanism 11 which is a light projecting and receiving mechanism 6, and the second mechanism 12 which is a light projecting and receiving mechanism 6 different from the first mechanism 11.

[0031] 2, 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.

[0032] 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.

[0033] 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. That is, each light-projecting and receiving mechanism 6 has 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.

[0034] The object whose passage is detected is not particularly limited, but may be, for example, an intruder.

[0035] As shown in FIG. 2, 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.

[0036] 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.

[0037] The upper light-projecting unit 71 and the lower light-projecting unit 72 are included in the light-projecting unit 2. Additionally, the upper light-receiving unit 81 and the lower light-receiving unit 82 are included in the light-receiving unit 3. That is, each light-projecting unit 7 is included in the light-projecting unit 2. Additionally, each light-receiving unit 8 is included in the light-receiving unit 3.

[0038] 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.

[0039] 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.

[0040] [Control mode] 3, the light-projecting unit 2 (more specifically, the light-projecting main body 21) has a light-projection control unit 23 and a light-projection side mode switching unit 24. The light-projection control unit 23 controls each light-projecting unit 7 (more specifically, the upper light-projecting unit 71 and the lower light-projecting unit 72). That is, the object detection device 1 is provided with the light-projection control unit 23 that controls each light-projecting unit 7.

[0041] The control mode of the light-projection control unit 23 can be switched between a first mode and a second mode. The first mode is a control mode for adjusting the optical axes of the light-projecting units 7 and the light-receiving units 8. The second mode is a control mode for detecting the passage of an object. In other words, the control mode of the light-projection control unit 23 can be switched between the first mode for adjusting the optical axes of the light-projecting units 7 and the light-receiving units 8, and the second mode for detecting the passage of an object.

[0042] Light-emitter-side mode switching unit 24 is configured to be able to switch the control mode of light-emitter control unit 23. In detail, light-emitter-side mode switching unit 24 is configured to detect whether light-emitter cover 22 is attached or detached.

[0043] Then, when light-projection-side mode switching unit 24 detects that light-projection cover 22 has been removed from light-projection main body 21, it switches the control mode of light-projection control unit 23 from the second mode to the first mode. Also, when light-projection-side mode switching unit 24 detects that light-projection cover 22 has been attached to light-projection main body 21, it switches the control mode of light-projection control unit 23 from the first mode to the second mode.

[0044] However, the present invention is not limited to this. The control mode of light-projection control unit 23 may be switched regardless of attachment / detachment of light-projection cover 22. For example, the control mode of light-projection control unit 23 may be switched by manually operating a selector switch (not shown).

[0045] 3, the light receiving unit 3 (more specifically, the light receiving main body 31) has a light receiving control unit 33 and a light receiving side mode switching unit 34. The light receiving control unit 33 controls each light receiving unit 8 (more specifically, the upper light receiving unit 81 and the lower light receiving unit 82).

[0046] The control mode of the light-receiving control section 33, like the light-emitting control section 23, is switchable between a first mode and a second mode.

[0047] The light-receiving-side mode switching unit 34 is configured to be able to switch the control mode of the light-receiving control unit 33. More specifically, the light-receiving-side mode switching unit 34 determines the control mode of the light-projecting control unit 23, and automatically switches the control mode of the light-receiving control unit 33 according to the control mode of the light-projecting control unit 23. More specifically, when the control mode of the light-projecting control unit 23 switches from the second mode to the first mode, the light-receiving-side mode switching unit 34 switches the control mode of the light-receiving control unit 33 from the second mode to the first mode. Also, when the control mode of the light-projecting control unit 23 switches from the first mode to the second mode, the light-receiving-side mode switching unit 34 switches the control mode of the light-receiving control unit 33 from the first mode to the second mode.

[0048] That is, the light-receiving-side mode switching unit 34 switches the control mode of the light-receiving control unit 33 so as to match the control mode of the light-projection control unit 23 .

[0049] Here, the determination of the control mode of the light-projection control unit 23 by the light-receiving-side mode switching unit 34 will be described in detail. 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 a pulsed state as shown in FIG. 4. The light-projection control unit 23 can execute temporary pause control. The temporary pause control is a control in which the interval between light projections by each light-projection unit 7 is temporarily extended. In other words, the light-projection control unit 23 can execute temporary pause control, which is a control in which the interval between light projections by the light-projection unit 7 is temporarily extended. In this specification, one pulse is considered to be one light projection.

[0050] 4, the light-projection control unit 23 pauses light projection once every time a predetermined number of light projections (N times) are performed. As a result, the interval between the last light projection of the predetermined number of light projections (N times) and the first light projection of the next predetermined number of light projections (N times) becomes longer than the interval between light projections in the predetermined number of light projections (N times). That is, the temporary pause control in this embodiment is control to pause light projection once.

[0051] The light-projection control unit 23 executes a temporary pause control every time a first predetermined number of light projections are performed in the first mode, and executes a temporary pause control every time a second predetermined number of light projections are performed in the second mode, where the first number and the second number are different from each other.

[0052] For example, "N" shown in Fig. 4 is the first number in the first mode and the second number in the second mode. Note that the first number and the second number may be any number as long as they are different from each other.

[0053] 3, the light-receiving-side mode switching unit 34 acquires, from the upper light-receiving unit 81, a detection result of the infrared rays 4 received by the upper light-receiving unit 81 (light projected by the light-projecting unit 7). In addition, the light-receiving-side mode switching unit 34 acquires, from the lower light-receiving unit 82, a detection result of the infrared rays 4 received by the lower light-receiving unit 82 (light projected by the light-projecting unit 7).

[0054] Then, the light-receiving-side mode switching unit 34 detects the interval of the temporary pause control based on the detection result of the infrared rays 4 (light projection by the light-projecting 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). That is, the light-receiving-side mode switching unit 34 detects how many times light projection has been performed after the temporary pause control has been performed until the next temporary pause control is performed. In this way, the light-receiving-side mode switching unit 34 determines the control mode of the light-projection control unit 23.

[0055] For example, when it is detected based on the detection result of infrared rays 4 received by the upper light receiving unit 81 that the interval between temporary pause controls is the first number of times (in other words, after a temporary pause control is executed, light projection is performed the first number of times before the next temporary pause control is executed), the light receiving side mode switching unit 34 determines that the control mode of the light projection control unit 23 is the first mode.

[0056] However, the present invention is not limited to this. The control mode of the light-receiving control unit 33 may be switched manually. For example, the control mode of the light-receiving control unit 33 may be switched by manually operating a changeover switch (not shown).

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

[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] However, the present invention is not limited to this. The alarm issued by the alarm issuing unit 35 may be an alarm that the passage of an object has been detected by sound, light, or the like. That is, the alarm issuing unit 35 may be configured to emit sound, light, or the like.

[0060] The object detection device 1 detects the passage of an object only when the light projection control unit 23 and the light reception control unit 33 are in the second mode. More specifically, the alarm unit 35 issues an alarm only when the light projection control unit 23 and the light reception control unit 33 are in the second mode.

[0061] In other words, the object detection device 1 does not detect the passage of an object when the light projection control unit 23 and the light reception control unit 33 are in the first mode. More specifically, the alarm emitting unit 35 does not emit an alarm when the light projection control unit 23 and the light reception control unit 33 are in the first mode. However, the present invention is not limited to this. The object detection device 1 may detect the passage of an object and the alarm emitting unit 35 may emit an alarm even when the light projection control unit 23 and the light reception control unit 33 are in the first mode. This allows an operation test to be performed in the first mode to confirm that the detection of the passage of an object and the alarm are functioning normally. The operation test may be performed by connecting a tester or the like for detecting the detection to the alarm emitting unit 35 and outputting an alarm signal from the alarm emitting unit 35 to the tester or the like instead of to the alarm device.

[0062] [Operation mode] The object detection device 1 has two operation modes, an AND mode and an OR mode. That is, the object detection device 1 is provided with the AND mode and the OR mode.

[0063] 3, the light projecting unit 2 (more specifically, the light projecting main body 21) and the light receiving unit 3 (more specifically, the light receiving main body 31) each have an operation mode setting unit 9. The operation mode setting unit 9 sets the operation mode of the object detection device 1 (in other words, the light projecting unit 2 and the light receiving unit 3) in response to a manual operation. Although not particularly limited, the operation mode setting unit 9 may set the operation mode based on, for example, a manual operation of a setting switch (not shown).

[0064] When the object detection device 1 is in the AND mode, and the light-projection control unit 23 and the light-reception control unit 33 are in the second mode, if the projection of the infrared rays 4 is interrupted in both the first mechanism 11 and the second mechanism 12, the alarm unit 35 issues an alarm. Note that, at this time, if 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 does not issue an alarm.

[0065] That is, in the AND mode, when the projection of the infrared rays 4 is interrupted in all of the plurality of light projecting and receiving mechanisms 6, an alarm is issued.

[0066] When the object detection device 1 is in the OR mode, and the light projection control unit 23 and the light receiving control unit 33 are in the second mode, if the projection of infrared light 4 is blocked by at least one of the first mechanism 11 and the second mechanism 12, an alarm is issued by the alarm issuing unit 35.

[0067] That is, in the OR mode, when the projection of the infrared ray 4 is interrupted in at least one of the plurality of light emitting and receiving mechanisms 6, an alarm is issued.

[0068] The light-projection control unit 23, the light-projection side mode switching unit 24, the light-reception control unit 33, the light-reception side mode switching unit 34, the alarm issuing unit 35, and the operation mode setting unit 9 may be physical devices such as a microcomputer, or may be functional units in software.

[0069] [Light emission control in the first mode] When the control mode of the light-projection control unit 23 is the first mode, the light-projection control unit 23 controls each light-projecting unit 7 so that the light-projecting pattern differs for each light-projecting and light-receiving mechanism 6, as shown in Fig. 5. Note that the light-projection pattern refers to a pattern of light projected by the light-projecting unit 7.

[0070] 5, the transition of the intensity (output level) of the infrared rays 4 projected from the upper light-projecting unit 71 in the first mode is shown as an "upper light-projecting stage." Also, the transition of the intensity (output level) of the infrared rays 4 projected from the lower light-projecting unit 72 in the first mode is shown as a "lower light-projecting stage."

[0071] 5, the light projection pattern of the lower light projector 72 is a pattern in which the light projection period is alternately switched between a first period T1 and a second period T2. That is, the light projection period of the light projector 7 in the second mechanism 12 is alternately switched between the first period T1 and the second period T2. The first period T1 and the second period T2 are different from each other.

[0072] Moreover, the light projection pattern of upper light projector 71 is a pattern in which the light projection cycle is maintained at third cycle T3.

[0073] In this manner, in this embodiment, when the control mode of the light projection control unit 23 is the first mode, the light projection pattern differs for each light projection and reception mechanism 6.

[0074] Furthermore, in this embodiment, when the control mode of the light-projection control unit 23 is the first mode, the light-projection control unit 23 can control each light-projection unit 7 so that the light-projection pattern is different from those of the other object detection devices 1. More specifically, for example, the light-projection control unit 23 may be able to control each light-projection unit 7 so that the light-projection period is different from those of the other object detection devices 1.

[0075] Also, for example, a light projection pattern may be individually selectable from a plurality of light projection patterns for each object detection device 1. In this case, if a different light projection pattern is selected for each object detection device 1, the light projection control unit 23 in each object detection device 1 controls each light projection unit 7 so that the light projection pattern is different from that of the other object detection devices 1.

[0076] In addition, when the control mode of the light-projection control unit 23 is the first mode, the light-projection control unit 23 controls each light-projection unit 7 so that the light projection and reception mechanism 6 projects light at a timing that avoids the projection of light from other light-projection and reception mechanisms 6, as shown in FIG. 5.

[0077] 5, the first period T1 is twice as long as the first time T4, and the second period T2 is twice as long as the second time T5. The first time T4 and the second time T5 are different from each other.

[0078] The third period T3 is the sum of the first time T4 and the second time T5. That is, the light projection period of the light projector 7 in the first mechanism 11 is the sum of the first time T4 and the second time T5 that is different from the first time T4.

[0079] By defining the first period T1, the second period T2, and the third period T3 in this manner and shifting the timing of the first light projection in each light projecting and receiving mechanism 6 from one another, the light projection in each light projecting and receiving mechanism 6 is avoided from the timing of light projection in each of the other light projecting and receiving mechanisms 6. Note that this "first light projection" may be the first light projection after the object detection device 1 is powered on, or may be the first light projection after the control mode of the light projection control unit 23 becomes the first mode.

[0080] That is, when the control mode of the light-projection control unit 23 is the first mode, the light-projection control unit 23 controls each light-projection unit 7 so that the light-projection pattern, which is the pattern of light projection by the light-projection unit 7, is different for each light-projection and receiving mechanism 6, and so that light projection in each light-projection and receiving mechanism 6 is performed to avoid the timing of light projection in other light-projection and receiving mechanisms 6.

[0081] [Switching the state of the light receiving unit] 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 the light emitted by the light projector 7 can be detected. The second state is a state in which the light emitted by the light projector 7 cannot be detected. In other words, each 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.

[0082] More specifically, in Fig. 5, the transition of the state of the upper light receiving section 81 in the first mode is shown as the "upper light receiving section". Also, the transition of the state of the lower light receiving section 82 in the first mode 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. 5, "ON" corresponds to the first state, and "OFF" corresponds to the second state.

[0083] As shown in FIG. 5, in the first mode, the upper light receiving unit 81 enters a first state to coincide with the light projection timing of the upper light projecting unit 71, and enters a second state when the upper light projecting unit 71 is not projecting light.

[0084] In the first mode, the lower light receiving section 82 goes into the first state 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.

[0085] In this manner, in the first mode, each light receiving section 8 alternately switches between the first state and the second state in synchronization with the light projection timing of the corresponding light projecting section 7.

[0086] Furthermore, when the object detection device 1 is in the OR mode and the light-projection control unit 23 and the light-reception control unit 33 are in the second mode, the light-projection units 7 and the light-reception units 8 are controlled in the same manner as in the first mode, except for the temporary pause control described above. That is, when the object detection device 1 is in the OR mode and the light-projection control unit 23 and the light-reception control unit 33 are in the second mode, the light-projection units 7 and the light-reception units 8 are controlled as shown in FIG.

[0087] When the object detection device 1 is in the AND mode, and the light-projection control unit 23 and the light-reception control unit 33 are in the second mode, the light-projection units 7 and the light-reception units 8 are controlled as shown in Fig. 6. Hereinafter, the control of the light-projection units 7 and the light-reception units 8 at this time is referred to as "AND mode control."

[0088] In FIG. 6, the transition of the intensity (output level) of infrared rays 4 projected from upper light-projecting section 71 and lower light-projecting section 72 in AND mode control is shown as "common to upper and lower light-projecting sections."

[0089] In the AND mode control, the upper light projector 71 and the lower light projector 72 project light at the same timing. In the AND mode control, light projection is performed at the light projection timing of the upper light projector 71 in the OR mode, and also at the light projection timing of the lower light projector 72 in the OR mode. This increases the frequency of light projection compared to the OR mode.

[0090] More specifically, as shown in FIG. 6, the light projection period in the AND mode control changes so that "second time T5, first time T4, first time T4, second time T5" is repeated.

[0091] 6, the transition of the states of the upper light-receiving section 81 and the lower light-receiving section 82 in AND mode control is shown as "common to upper and lower light-receiving sections." In the graph of "common to upper and lower light-receiving sections" in FIG. 6, "ON" corresponds to the first state, and "OFF" corresponds to the second state.

[0092] As shown in FIG. 6, in the AND mode control, the upper light receiving section 81 and the lower light receiving section 82 are always in the first state.

[0093] That is, when the control mode of the light-projection control unit 23 is the second mode, in the AND mode, each light-receiving unit 8 is always in the first state, and in the OR mode, each light-receiving unit 8 alternates between the first state and the second state in synchronization with the light-projection timing of the corresponding light-projecting unit 7.

[0094] [About synchronization] In the following, a detailed description will be given of the control for synchronizing the state switching of the light receiving unit 8 with the light projection timing of the light projecting unit 7 when the light projection control unit 23 and the light reception control unit 33 are switched to the first mode.

[0095] 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 spread out in a fan shape reach the upper light-receiving unit 81. Also, 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 spread out in a fan shape reach the lower light-receiving unit 82. However, the present invention is not limited to this. The upper light-receiving unit 81 may be configured so that the infrared rays 4 from the lower light-projecting unit 72 do not reach (are not received by) the lower light-receiving unit 82. Also, it is assumed that the infrared rays 4 from the upper light-projecting unit 71 do not reach (are not received by) the lower light-receiving unit 82.

[0096] When the light-receiving control unit 33 is switched to the first mode, the light-receiving control unit 33 executes synchronization start control. The synchronization 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 synchronization 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.

[0097] 3, 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.

[0098] 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.

[0099] Furthermore, from the time when the light receiving control unit 33 enters the first mode until the state switching of the upper light receiving unit 81 begins in synchronization with the light projection timing of the upper light projector 71, the upper light receiving unit 81 may always be in the first state.

[0100] 3, 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.

[0101] 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.

[0102] Furthermore, from the time when the light receiving control unit 33 enters the first mode until the state switching of the lower light receiving unit 82 begins in synchronization with the light projection timing of the lower light projecting unit 72, the lower light receiving unit 82 may always be in the first state.

[0103] 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.

[0104] After the synchronization start control ends, each light-receiving unit 8 detects light emitted from the corresponding light-projecting unit 7, and does not detect light emitted from the non-corresponding light-projecting unit 7. Therefore, the adjustment work of the optical axes of the multiple light-projecting and receiving mechanisms 6 can be performed simultaneously without stopping light projection from each light-projecting and receiving mechanism 6.

[0105] Note that the object detection device 1 may be provided with a plurality of indicators (not shown) corresponding to the plurality of light receiving sections 8. The indicators may be configured to indicate the intensity (input level) of the infrared rays 4 received by the corresponding light receiving sections 8 during the optical axis adjustment work. The indicators may be provided in the light receiving unit 3, for example. The user can appropriately perform the optical axis adjustment work by looking at the indicators.

[0106] According to the configuration described above, when the control mode of the light projection control unit 23 is the first mode, the light projection / reception mechanism 6 projects light while avoiding the timing of light projection by other light projection / reception mechanisms 6. This makes it possible to avoid a situation in which the light projection timings of a plurality of light projection / reception mechanisms 6 coincide with each other, resulting in a decrease in the accuracy of adjustment of the optical axis.

[0107] Furthermore, according to the configuration described above, when the control mode of the light-projection control unit 23 is the first mode, the light projection pattern differs for each light-projecting and receiving mechanism 6. This makes it possible to identify, based on the infrared rays 4 received by the light-receiving unit 8, the infrared rays 4 projected from which light-projecting unit 7 of which light-projecting and receiving mechanism 6 the infrared rays 4 have been projected. Therefore, in the optical axis adjustment work, while adjusting the optical axis of one of the multiple light-projecting and receiving mechanisms 6, it is not necessary to stop light projection from the other light-projecting and receiving mechanisms 6. In other words, the optical axis adjustment work of the multiple light-projecting and receiving mechanisms 6 can be performed simultaneously.

[0108] Therefore, according to the configuration described above, it is possible to realize an object detection device 1 that is capable of adjusting the optical axis with high precision while reducing the labor required for adjusting the optical axis.

[0109] Other embodiments (1) One light-projecting unit 7 may have a plurality of light-projecting elements. In other words, one light-projecting unit 7 may project a plurality of infrared rays 4. In that case, one light-receiving unit 8 may have a plurality of light-receiving elements.

[0110] (2) In the above embodiment, the light-projection period in the first mechanism 11 and the second mechanism 12 when the light-projection control unit 23 is in the first mode is determined by a combination of two types of time, the first time T4 and the second time T5. However, the present invention is not limited to this. The light-projection period may be determined by a combination of three types of time, or may be set randomly, for example.

[0111] (3) The configuration may be such that the temporary pause control is not executed.

[0112] (4) The first mechanism 11 may be located at the bottom of the object detection device 1, and the second mechanism 12 may be located at the top of the object detection device 1.

[0113] (5) Either the AND mode or the OR mode does not have to be provided.

[0114] (6) The light emitting and receiving mechanisms 6 do not have to be aligned vertically.

[0115] 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]

[0116] The present invention can be used in an object detection device and an object detection system. [Explanation of symbols]

[0117] 1: Object detection device 2: Light projection unit 3: Light receiving unit 4: Infrared 6: Light emitting and receiving mechanism 7: Light projection section 8: Light receiving part 11: 1st mechanism 12:Second mechanism 23: Light emission control section A: Object detection system T1: 1st period T2: 2nd period T4: First Hour T5: 2nd Hour

Claims

1. A plurality of light emitting and receiving mechanisms are provided, Each of the light projecting and receiving mechanisms includes a light projecting unit that projects infrared rays and a light receiving unit that receives the infrared rays 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-projection control unit for controlling each of the light-projecting units, The control mode of the light projection control unit is switchable between a first mode for adjusting the optical axes of the light projection units and the light receiving units and a second mode for detecting the passage of an object; An object detection device in which, when the control mode of the light-projection control unit is the first mode, the light-projection control unit controls each of the light-projecting units so that a light-projection pattern, which is the pattern of light projected by the light-projecting unit, is different for each of the light-projecting and receiving mechanisms, and so that light projection in each of the light-projecting and receiving mechanisms is performed to avoid the timing of light projection in the other light-projecting and receiving mechanisms.

2. a first mechanism which is the light emitting / receiving mechanism, and a second mechanism which is the light emitting / receiving mechanism different from the first mechanism, a light-projection period of the light-projecting unit in the first mechanism is a sum of a first time and a second time different from the first time, a light projection period of the light projection unit in the second mechanism is alternately switched between a first period and a second period; the first period is twice as long as the first time; 2. The object detection device according to claim 1, wherein the second period is twice as long as the second time period.

3. the light-projection control unit is capable of executing a temporary pause control that is a control for temporarily lengthening an interval between light projections by the light-projecting unit, the light-projection control unit executes the temporary pause control every time a predetermined first number of light projections are performed in the first mode, and executes the temporary pause control every time a predetermined second number of light projections are performed in the second mode; The object detection device according to claim 1 , wherein the first number of times and the second number of times are different from each other.

4. An AND mode and an OR mode are provided, In the AND mode, an alarm is issued when infrared light projection is interrupted in all of the plurality of light projection and reception mechanisms. In the OR mode, an alarm is issued when infrared light is blocked from at least one of the plurality of light emitting and receiving mechanisms, Each of the light receiving units 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 emitted by the light projecting unit cannot be detected, 3. The object detection device according to claim 1, wherein when the control mode of the light-projecting control unit is the second mode, in the AND mode, each of the light-receiving units is always in the first state, and in the OR mode, each of the light-receiving units alternates between the first state and the second state in synchronization with the light-projecting timing of the corresponding light-projecting unit.

5. The plurality of light emitting and receiving mechanisms are arranged vertically, A light-projecting unit and a light-receiving unit are provided so as to be spaced apart from each other, Each of the light-projecting sections is included in the light-projecting unit, The object detection device according to claim 1 or 2, wherein each of the light receiving sections is included in the light receiving unit.

6. An object detection system including a plurality of object detection devices according to claim 1 or 2, An object detection system, wherein when the control mode of the light-projection control unit is the first mode, the light-projection control unit is capable of controlling each of the light-projection units so that the light-projection pattern is different from those of the other object detection devices.

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