JP2014181993A - Security device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a security device which includes a rotary mirror rotated by a motor, emits laser light for scanning from the rotary mirror, and detects a direction where a reflection object is present and a distance to the reflection object by receiving reflection light of the emitted laser light, wherein, upon receiving laser light, the security device discriminates whether or not the received laser light is the laser light emitted from other security device.SOLUTION: In a plurality of times of rotations of a rotary mirror 11, when the security device continuously receives reflection laser light at a same rotation angle position, if there are changes in time periods from emission to reception of the laser light of the reflection laser light having received the plurality of times and there is no change in the reception light intensity of the reflection laser light, the security device determines that the received laser light is not emitted by itself but emitted from another security device.

Description

  The present invention relates to a security device for detecting an intruder by a laser radar.

  In a security device equipped with a laser radar, as seen in Patent Document 1, a laser beam is emitted in a horizontal direction at a predetermined angular interval, and a reflected light (reflected laser beam) of the emitted laser beam is received to be suspicious. It is detected that the person has entered the monitoring area, and the direction in which the suspicious person is present and the distance to the suspicious person are detected.

  In order to emit laser light at a predetermined angular interval in the horizontal direction, a light projecting element that emits laser light and a mirror that is provided at an angle and reflects the laser light emitted from the light projecting element toward the front horizontally. And a motor that rotationally drives the mirror at a constant speed, and emits laser light in a pulse form from the light projecting element each time the mirror (hereinafter referred to as a rotating mirror) rotates by a predetermined angle. When a suspicious person enters the monitoring area, the emitted laser light strikes the suspicious person and is reflected, so that the reflected laser light is incident on the rotating mirror and reflected and received by the light receiving element.

  When the control device receives the reflected laser beam with the light receiving element, the control device detects the time from when the light projecting element emits the laser light to when the light receiving element receives the reflected laser light, and based on this time, Calculate the distance. Further, the laser beam emission direction, that is, the direction in which the suspicious person is present is detected based on the rotation angle position of the rotary mirror when the light projecting element emits the laser beam. And the position where a suspicious person exists is specified from this distance and direction.

JP 2010-102697 A

  For example, when a wide area is monitored in the horizontal direction (horizontal direction), the wide area may not be carried by a single security device. In this case, for example, two security devices are installed apart from each other in the horizontal direction, and half of each area is set as an area in charge of each security device to detect the intrusion of a suspicious person.

  When two security devices are installed side by side in the horizontal direction, etc., if a trap or the like stands in front of the monitoring area, the laser light emitted from the two security devices hits the front trap and reflects. The reflected laser light may enter the rotating mirror of the other security device, and the light receiving element may receive the light. Then, the two security devices erroneously detect that a suspicious person has entered the monitoring area.

In order to eliminate such erroneous detection, conventionally, even if the laser light emitted from the security device on the other side is reflected by the heel of two security device motors, the reflected laser light is incident on the rotating mirror. The rotation angle is set so that the rotation angle is not set so as to be rotated.
However, the motors provided in the two security devices do not rotate at exactly the same speed, but usually have a slight speed difference. For this reason, due to long-term use, the rotational positional relationship of the motors of the two security devices is shifted, and the laser beams emitted from the two security devices and reflected by the scissors eventually become the other security device. Incident on the rotating mirror and received by the receiver element. As a result, the two security devices erroneously detect the intrusion of the suspicious person even though there is no suspicious person.

  The present invention has been made in view of the above circumstances, and when the reflected laser beam is received, it is possible to determine whether this is due to the laser beam emitted from another security device. It is to provide a security device.

  In two security devices, due to long-term use, when their rotating mirrors are in a rotational angular position relationship such that they receive laser light emitted from the other security device and reflected by a scissors or the like, Since the difference in the rotational speed of the motors of the two security devices is negligible, the rotational angle positional relationship continues for a while.

  During this time, the rotating mirror rotates a plurality of times. During a plurality of rotations of the rotating mirror, in the two security devices, there is almost no change in the optical path length of the laser light until it receives the laser light emitted from the other side and reflected by the eaves or the like. For this reason, when the reflected laser beam from the ridge of the security device on the other side is received, the received light intensity does not change while the rotating mirror rotates a plurality of times, and shows the same received light intensity.

  In contrast, since the time required for one rotation of the motors of the two security devices is slightly different, the time required for the rotation mirror to make one rotation and reach the same rotation angle position as before is the same for the two security devices. Slightly different. For this reason, when the other security device receives the laser beam emitted from one security device and reflected by a bag or the like, in the other security device, after the laser beam is emitted from the one security device, The time until the reflected laser beam is received (required light reception time) slightly changes for each rotation of the rotating mirror.

  That is, when the rotating mirror of the one security device is rotated at a higher speed (slower speed) than the rotating mirror of the other security device, the laser beam emission time at each rotation angle position of the rotating mirror is set as the reference time. The reference time at the rotation angle position of one security device is advanced (delayed) with respect to the reference time at the rotation angle position of the other security device, and as a result, the time required for light reception is early (slow). Become. Even if this change in the time required for light reception is slight, the speed of light is very fast, so the other security device detects that the distance to the reflecting object has changed.

Of course, when the laser beam emitted from itself is reflected by a reflecting object such as a heel and receives the reflected laser beam, the received light intensity does not change during the rotation of the rotating mirror, and the laser beam The time from the emission time (reference time) to the light reception time (time required for light reception) does not change (the distance to the reflecting object does not change). In addition, when the laser beam emitted from itself is reflected by a moving object such as a person and the reflected laser beam is received, the distance to the reflecting object changes during multiple rotations of the rotating mirror. Both the time required for light reception changes.
Accordingly, when it is detected that the required light reception time is changed but the received light intensity is not changed, it can be determined that the reflected light of the laser light emitted from the other has been received.

  The present invention has been made on the basis of the above consideration of the relationship between the time required for light reception and the light reception intensity.

In the present invention, when the laser beam is continuously received a plurality of times at the same rotational position in a plurality of rotations of the rotating mirror, the time from the emission of the laser beam to the reception (required time for light reception) changes, and the light is received. When there is no change in intensity, there is provided determination means for determining that the reflected laser beam of the laser beam emitted from the other is received instead of the laser beam emitted by itself.
In the present invention having this configuration, it is possible to determine whether the reflected laser beam emitted from itself or the reflected laser beam emitted from another has been detected.

The block diagram which shows one Embodiment of this invention and shows the electrical structure of a process part Longitudinal side view of sensor Plan view showing the case of monitoring the site with two security devices The figure which shows the relation between the change of the distance to the reflective object and the change of the light reception timing and the light reception intensity A graph showing the relationship between the distance to the reflective object and the received light intensity Plan view when receiving laser light emitted from another security device Wave diagram of each signal when receiving laser light emitted from other security devices Flowchart 1 showing processing contents for distance data and received light intensity data Flowchart 2 showing processing contents for distance data and received light intensity data

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
The security device includes a sensor unit 1 shown in FIG. 2 and a processing unit 2 shown in FIG. For example, the security device detects a suspicious person who enters the site 4 of the house 3 shown in FIG. In the example of FIG. 3, two security devices indicated by A and B are installed.

  As shown in FIG. 2, the sensor unit 1 is attached to the outer wall 5 of the house 3. The sensor unit 1 emits scanning light, that is, laser light toward the front monitoring area, and the emitted laser light (hereinafter referred to as emitted laser light L) is reflected by a reflecting object (including a person) and returned. The incoming laser beam (hereinafter, reflected laser beam M) is detected (received).

  The sensor unit 1 is provided with a laser light emitting unit 7 and a light receiving unit 8 in a body case 6 fixed to the outer wall 5. The laser beam emitting unit 7 is a semiconductor laser 9 as a light projecting element, a fixed mirror 10 that is disposed at an angle of 45 ° in front of the semiconductor laser 9, and a tilt angle of 45 ° below the fixed mirror 10 that is rotated at an angle of 45 °. And a rotating mirror 11 arranged in a possible manner. The fixed mirror 10 has a lower surface as a mirror surface, and the rotary mirror 11 has an upper surface as a mirror surface.

A motor 12 made of, for example, a direct current motor controlled by an inverter is fixed to the inner bottom surface of the main body case 6. The rotation axis 12a of the motor 12 is vertically upward, and the rotation center line thereof coincides with the laser light L reflected vertically downward by the fixed mirror 11.
Laser light is emitted horizontally from the semiconductor laser 9 forward. The emitted laser beam L is reflected vertically downward by the fixed mirror 10, further reflected horizontally by the rotating mirror 11, and out of the main body case 6 from the window 6 a formed from the front surface of the main body case 6 to the left and right side surfaces. Is emitted. A transparent cover 13 is attached to the window 6a.

  The rotating mirror 11 is rotated at a constant speed by the motor 12. For this reason, the emitted laser light L reflected by the rotating mirror 11 is emitted within one horizontal plane, and the emitting direction thereof varies depending on the rotational angle position of the rotating mirror 11 and, consequently, the motor 12. In this embodiment, while the motor 12 rotates from 0 ° to 180 °, the laser beam is emitted for a short time each time it rotates 1 ° including 0 °. Accordingly, the emitted laser light L is pulsed.

  Here, as shown in FIG. 3, when a straight line is drawn directly in front of the main body case 6 through the central axis of the rotating shaft 12a, this straight line has a rotation angle position of 90 ° and a straight line at the rotation angle position of 90 °. The positions when rotated 90 ° clockwise and counterclockwise around the rotation axis 12a are defined as the rotation angle position 0 ° and the rotation angle position 180 °. Accordingly, the straight lines at the rotation angle positions of 0 ° and 180 ° are substantially parallel to the outer wall 5 of the house 3.

  On the other hand, the light receiving unit 8 includes a perforated fixed mirror 14, a condenser lens 15, and a photodiode 16 as a light receiving element. The perforated fixed mirror 14 is disposed at an angle of 45 ° between the fixed mirror 10 and the rotating mirror 11 of the laser light emitting unit 7. The perforated fixed mirror 14 has a hole 14a through which the outgoing laser light L reflected by the fixed mirror 10 passes at the center. The perforated fixed mirror 14 has a mirror surface on the lower surface.

  The emitted laser light L emitted from the window 6a of the main body case 6 hits an object and is reflected. The laser beam M reflected by the reflecting object enters the main body case 6 through the window 6a, enters the rotating mirror 11, and is reflected vertically upward. Then, the reflected laser beam M reflected by the fixed mirror 11 is reflected toward the condenser lens 15 by the perforated fixed mirror 14 and condensed by the condenser lens 15. The photodiode 16 receives the reflected laser light M collected by the condenser lens 15.

  The processing unit 2 is provided in the main body case 6 or configured separately from the main body case 6 and installed in the house 3. The processing unit 2 includes a control device (control means) 17 as shown in FIG. The control device 17 is configured mainly with a microcomputer including a CPU, a ROM, a RAM, and the like. The control device 17 controls the motor 12. That is, the motor 12 is provided with a rotation detection device (rotation detection means) 18 such as a frequency generator or a rotary encoder for detecting the rotation position of the rotation shaft 12a. The rotation detection device 18 is connected to the control device 17 at the rotation shaft 12a. Rotation position information is sent. The control device 17 detects the rotational speed of the rotary shaft 12a from the rotational position information, compares the detected rotational speed with the target rotational speed, and performs inverter control of the motor 12 so that the rotational shaft 12a becomes the target rotational speed.

  Further, when the control device 17 detects from the rotational position information from the rotation detection device 18 that the rotation shaft 12a has rotated to the rotation angle position of 0 °, it sends an output signal to the semiconductor laser 9, and thereafter the rotation shaft 12a. Each time it detects that it has rotated 1 ° while rotating to a rotation angle position of 180 °, it sends an output signal to the semiconductor laser 9. When receiving an output signal from the control device 17, the semiconductor laser 9 outputs laser light for a very short time, that is, emits pulsed laser light. Thereby, pulsed laser light (scanning light) is sequentially emitted from the sensor unit 1 toward the monitoring area at intervals of 1 ° between the rotation angle positions of 0 ° and 180 °.

  The photodiode 16 generates a current corresponding to the amount of received light. An amplifier 19 is connected to the photodiode 16, and the current generated by the photodiode 16 is amplified by the amplifier 19. In addition, a current-voltage conversion circuit 20 is connected to the amplifier 19, and the current amplified by the amplifier 19 is converted into a voltage corresponding to the current by the current-voltage conversion circuit 20.

The conversion voltage of the current-voltage conversion circuit 20 is input to the non-inverting input terminal V ⁺ of the comparator 21. Inverting input terminal V of the comparator 20 ^- the reference voltage applied to the current in the absence of incidence of the reflected laser beam M - and voltage conversion circuit 20 is defined to the value of a degree exceeding slightly the voltage generated. When the voltage (conversion voltage of the current-voltage conversion circuit 20) input to the non-inverting input terminal V ⁺ becomes higher than the reference voltage, that is, when the reflected laser beam M is incident, the comparator 21 reflects the reflection. A light reception signal for notifying that the laser beam M has been detected is output.

  The light reception signal output from the comparator 21 is given to a time measurement IC (time measurement means) 22 connected to the control device 17 and also to the control device 17 itself. The control device 17 outputs an output signal to the semiconductor laser 9 and simultaneously outputs a start signal to the time measurement IC 22. When the time measurement IC 22 receives the start signal from the control device 17 (when the emitted laser light L is emitted from the semiconductor laser 9), the time measurement IC 22 measures the time t from that time to the time when the light reception signal is input from the comparator 21. To do. The measurement time t is given to the control device 17, and the control device 17 calculates the distance to the reflecting object based on the time t.

  The output voltage of the current-voltage conversion circuit 20 is also supplied to the peak value detection circuit 23. Each time the photodiode 16 receives the reflected laser light M, the peak value detection circuit 23 detects the maximum value of the received light intensity as the maximum value of the output voltage of the current-voltage conversion circuit 20, and the detected voltage value Is given to the control device 17.

When the light reception signal is input from the comparator 21, the control device 17 determines whether or not a suspicious person has entered based on the time given from the time measurement IC 22 and the voltage value given from the peak value detection circuit 23.
Further, the control device 17 determines whether or not the light received by the photodiode 16 is reflected light of the laser light emitted from its own semiconductor laser 9 (determination means). Prior to explaining this determination operation, it will be explained that the laser light received by the photodiode 16 may not be the reflected light of the laser light emitted from its own semiconductor laser 9.

In other words, in the example shown in FIG. 3, two security devices A and B are installed on the outer wall 5 of the house 3, and the site 4 is monitored by these security devices A and B. A fence 24 is installed around the site 4, and the laser light emitted from the security devices A and B strikes and reflects the fence 24.
Under this circumstance, as shown in FIG. 6, depending on the rotation angle position of the rotating mirror 11 of the two security devices A and B, the laser beams emitted from the other security device and reflected by the flange 24 In some cases, the light enters the rotating mirror 11 and the photodiode 16 receives the laser light reflected by the reflecting mirror 11. Then, the security device may erroneously determine that there is an intruder even though there is no intruder.

  In order to eliminate the influence of the laser beam emitted from such other security devices, for example, when the two security devices A and B are installed, both of the rotating mirrors 11 rotate from the 0 ° position. Initialize to If the two security devices are initially set in this way, even if the laser beams emitted from the other security device collide with each other and are reflected by the flange 24, the reflected light is reflected on the photodiode 16 thereof. Will not receive light.

However, the characteristics of the motor 12 are different one by one. For example, even if the motor 12 is set to rotate once in 1 sec for control, actually, for example, although the motor 12 of one security device A rotates exactly once in 1 sec, the other security device The characteristics of the motors 12 of the two security devices A and B are different such that the motor 12 of the B rotates once in 1.0000001 (1 + 1/10 ⁸ ) sec.

  Then, when the two security devices A and B are installed, even if they are initially set so that both of the rotating mirrors 11 start to rotate from the 0 ° position, the two security devices are used for a long time. The rotational angle positional relationship of the A and B motors 12 gradually deviates from the initial setting state, and the laser light emitted from the other security device and reflected by the flange 24 enters the rotating mirror 11 and enters the photodiode. A situation occurs in which 16 receives light. When such a situation occurs, the difference in rotational speed between the motors 12 of the two security devices A and B is negligible. For this reason, the reflected laser light from the other security device is received for a while. It will continue.

  In this embodiment, when it is detected that the photodiode 16 has received a laser beam, it is determined whether the laser beam is emitted from the counterpart security device, and the laser emitted from the counterpart security device is determined. If it is light, the motor 12 is restarted so that the laser light emitted from the security device on the other side is not received.

  Such control is performed by executing a program stored in a storage means, for example, a ROM. The operation of the control device 17 performed according to this program will be described below with reference to the flowcharts of FIGS. 8 and 9, n is an integer from 0 to 180, and represents the rotational angle position at which the laser beam is emitted.

  Power on security devices A and B. Then, the control devices 17 of the security devices A and B perform rotation control so that the motor 12 rotates once in 1 sec. Each time the motor 12 rotates once, a pulsed laser beam L is emitted from the semiconductor laser 9 every time it rotates by 1 ° from the rotation angle position of 0 ° to 180 °. Each time the laser beam L is emitted from the semiconductor laser 9, the time until the photodiode 16 receives the reflected laser beam M from the emission point (reference point) of the laser beam L to the control device 17 (light reception). (Required time) t is input from the time measurement IC 22, and the received light intensity of the photodiode 16 is input from the peak value detection circuit 23.

  That is, in the monitoring area in front of each of the security devices A and B, a total of 181 laser beams are every 1 ° in a plane space from the rotation angle position 0 ° to 180 ° of the motor 12 (rotating mirror 11). The time required for light reception and the light reception intensity are obtained for each of the output and emitted laser beams.

  And the control apparatus 17 calculates the distance from the light reception required time t given from the time measurement IC22 to a reflective object (S1-S4 of FIG. 8). Thereafter, the control device 17 stores both data of the distance to the reflecting object and the received light intensity for each of the emitted laser beams L during one rotation of the motor 12 in, for example, both areas A1 and B1 of the RAM as storage means. For example, the number of consecutive misperceptions E (n) stored in the RAM (storage means) is set to 0 (S5 to S8 in FIG. 8).

  Subsequently, during the next one rotation of the motor 12, the control device 17 receives light for each laser beam L emitted every 1 ° in the plane space from the rotation angle position 0 ° to 180 °. The distance from t to the reflecting object is calculated and the received light intensity is acquired (S9 to S12 in FIG. 8). Then, the control device 17 stores both data of the distance to the reflecting object and the received light intensity for each of the obtained emitted laser beams in both areas A2 and B2 of the RAM in the same manner as described above (S13 in FIG. 9). To S16).

  Next, for each of the 181 laser beams output in the same rotation angle position (n) direction, the control device 17 receives the received light intensity of one rotation of the previous motor 12 and one rotation of the current motor 12. It is determined whether or not the received light intensity is the same (S17, S18 in FIG. 9: received light intensity difference calculating means). Whether the received light intensity at this time is the same may be determined based on whether or not they are exactly the same, but in the case of the present embodiment, for example, a predetermined ratio of the received light intensity of the previous time (or this time). The values that rise and fall within the range are determined to be the same.

  If there is a difference in the received light intensity, the control device 17 repeats the operation of comparing the previous and current received light intensity for the laser light emitted at the next rotation angle position (“NO” in S18, “NO” in S19, S20). "Repeat S18). When the received light intensity is the same (“YES” in S18), the control device 17 proceeds to S21 and determines whether or not the distance to the reflecting object is a difference of 30 cm or less between the previous time and the current time ( Distance difference calculation means).

  As will be apparent from the following description, the fact that the received light intensity is usually the same means that the reflecting object is stationary or hardly moves. Therefore, the control device 17 always determines “YES” in S21. Thereafter, the process proceeds to S19 and returns to the comparison operation of the received light intensity (after determining “YES” in S21, “NO” in S19 and S20, S18).

  When the comparison of the received light intensity is performed for all of the 181 outgoing laser beams L, the control device 17 becomes “YES” in S20 and proceeds to S22. Then, the control device 17 has the same number of consecutive misidentification times E (n) from the rotation angle position 0 ° to 180 ° in one rotation of the rotating mirror 11 this time as the E (n) in one rotation of the rotating mirror 11 last time. It is determined whether it is a numerical value (S23). If they are the same, the control device 17 clears the same E (n) to 0 (“YES” in S23, S24), and proceeds to S25.

  In addition, the controller 17 determines that the number of consecutive misidentifications E (n) at any rotation angle position from 0 ° to 180 ° in S23 is E (n) in the previous rotation of the rotary mirror 11. If it is not the same numerical value as the above and is larger by 1 than the previous time (“NO” in S23), the previous E (n) is deleted, the current E (n) value is stored in the RAM, and the process proceeds to S25. The purpose of the processes in S23 and S24 will be described later.

  In S25, the control device 17 stores the light reception required time data and the light reception intensity data at the rotation angle positions 0 ° to 180 ° in the current one rotation stored in both the areas A2 and B2 of the RAM, respectively. Copy to both areas (S25-S27). As a result, the light reception required time data and light reception intensity data for the previous rotation stored in both the areas A1 and B1 are deleted.

  Thereafter, the control device 17 obtains the distance data and light reception intensity data for the next one rotation, and in the same manner as described above, the light reception required time data and the light reception intensity data between the rotation angle positions 0 ° to 180 ° are obtained. Store in each area of RAM A2 and B2 (S9-S12). Subsequently, in the same manner as the previous operation, the control device 17 receives the required light reception time data and the received light intensity data at the rotation angle positions 0 ° to 180 ° in the current rotation stored in the areas A2 and B2 of the RAM, The light reception required time data and the light reception intensity data at the rotation angle positions 0 ° to 180 ° in the previous one rotation stored in the areas A1 and B1 are compared (“NO” in S18, “NO” in S19, S20). Repeat, or after determining “YES” in S18 and “YES” in S21, repeat “NO” and S18 in S19 and S20).

  By the way, when there is a difference between the previous and current received light intensity for one laser beam L emitted in a certain rotation angle position direction (“NO” in S18), the control device 17 performs a suspicious person intrusion alarm process. . This suspicious person intrusion alarm process has no direct relationship with the present invention and is not shown in the flowcharts of FIGS.

  In other words, when the reflective object is a person (suspicious person), the person moves with some degree. As shown in FIG. 4, when the reflective object is near the security device (a-1) and when it is far (b-1), as shown in (a-2) and (b-2), The closer the time from the emission of the emitted laser beam L to the reception of the reflected laser beam M reflected by the reflecting object is shorter (t1 <t2), and the closer the received light intensity is, the stronger (h1> h2). The relationship between the distance to the reflecting object and the received light intensity is as shown in the graph in FIG. Accordingly, when a person (suspicious person) enters the monitoring area, the person moves, so the time required for receiving light from the emission of the laser light L to the reception of the reflected laser light M is one rotation of the previous time and one of the current time. It is different from rotation.

  Therefore, the control device 17 compares the time required for light reception between the previous time and the current time for a certain rotation angle position direction, and if there is a difference between the two, determines that there is a suspicious person, and determines the rotation angle position direction as the suspicious person. The distance to the suspicious person is calculated from the current time required for receiving light, and a suspicious person intrusion warning process is performed.

  In addition, when the light reception intensity of the previous time and this time are the same (“YES” in S18), and the distance to the reflecting object is not less than 30 cm between the previous time and this time (“YES” in S21), A suspicious person is considered to be stationary so as not to move intentionally, and in addition, if the difference in distance is zero and there is no movement, it is determined as a stationary object. In other words, even if the person is consciously trying to stand still, it will move somewhat, so if it is more than 0 and 30 cm or less, it will be judged that there is a suspicious person who is not moving consciously, A suspicious person intrusion alarm process similar to that described above is performed.

  Now, if there is a slight difference (usually) between the rotational speeds of the motors 12 in the two security devices A and B, the laser light emitted from one security device during long-term use. Is reflected by the ridge 24 and incident on the rotating mirror 11 of the other security device, received by the photodiode 16, and the laser light emitted from the other security device is reflected by the ridge 24 and is reflected by one of the security devices. The light enters the rotating mirror 11 and is received by the photodiode 16.

  FIG. 6 shows that when viewed from one security device A, the laser beam emitted from the other security device B is reflected by the flange 24 at a certain rotational angle position of the motor 12 and is rotated by the rotating mirror 11 of the security device A. Is shown, and the light received by the photodiode 16 is shown.

Once in such a situation, the difference in rotational speed between the two motors 12 is negligible, so that the light is emitted from the other security device B at the same rotational angle position and reflected by the flange 24. The state of receiving the emitted laser beam continues for a while. During this time, as described above, the rotational speed difference between the motors 12 of both security devices A and B is such that one makes exactly one revolution in 1 sec, while the other makes one revolution in (1 + 1/10 ⁸ ) sec. Assuming that, the timing of receiving the laser beam emitted from the other security device B and reflected by the flange 24 is delayed by 1/10 ⁸ sec for each rotation of the motor 12.

Here, it is assumed that the shift in the light reception timing is captured as a result of the movement of the reflecting object. Then, since the speed of light is about 300,000 km (3 × 10 ¹⁰ cm), the delay in the light reception timing is 1/10 ⁸ sec. The delay of the laser light from when the laser light is emitted until it is reflected by the reflecting object and returned. Since the optical path length is increased by 3 × 10 ¹⁰ cm / 10 ⁸ = 300 cm, the distance to the reflective object is equivalent to ½ of that, that is, 150 cm longer.

  On the other hand, the received light intensity is the same between the previous time and this time. When one security device A receives the laser beam emitted from the other security device B and reflected by the flange 24 during the previous rotation of the motor 12 and the current rotation, it is emitted from the security device B. This is because there is almost no change in the optical path length of the laser light from when the security device A is received until the previous time and this time.

  The above is shown in FIG. 7A shows the first rotation, FIG. 7B shows the second rotation, and FIG. 7C shows the third rotation. In addition, when one security device itself emits laser light, the laser light emitted from the other security device is emitted from the other security device and reflected by the flange 24. The time when light is received is shown, and “light reception intensity” indicates the light reception intensity at the time of “laser light reception from another”.

  As is apparent from FIG. 7, at the second rotation, the time of receiving the laser light from the other is delayed from the time of emitting the emitted laser light, but the received light intensity of the laser light received from the other is the same as the first time. h0 is shown. Furthermore, at the time of the third rotation, the time of receiving the laser beam from the other is delayed more than the time of receiving the laser beam from the other, but the received light intensity of the laser beam received from the other is the same as the second time. Intensity h0 is indicated and there is no change.

  For this reason, when the laser beam emitted from the other security device and reflected by the flange 24 is received, the control device 17 determines “YES” in S18 of FIG. Then, since the distance to the reflecting object has changed beyond 30 cm, the control device 17 determines “NO” in the next S21, and increments the consecutive misidentification frequency E (n) in the subsequent S28.

  Then, the control device 17 determines whether or not E (n) is 5 or more in the next S29, and if it is less than 5 (“NO” in S29), the rotation angle position n is incremented and n is 180. If it is less, the process returns to S18, and it is determined whether or not the received light intensity at the next 1 ° rotated position is the same as the received light intensity at the same rotation angle position in the previous one rotation. Thereafter, the above-described operation is performed until n reaches 180 (“NO” in S18, “NO” in S19, S20, “YES” in S18, “YES” in S21, “NO” in S19, S20, or “YES” in S18, “NO” in S21, “NO” in S28 to S30, and S31).

  When n becomes 180 and “YES” in S20 or “YES” in S31, the control device 17 proceeds to S22. Then, as described above, the control device 17 determines whether or not the current consecutive misidentification frequency E (n) is the same value as the previous E (n) (S24: consecutive misidentification frequency difference calculating means). If they are the same, E (n) is cleared to 0, and if not, E (n) is replaced with the current value (1 greater than the previous time) (“YES” in S23, S24). Next, the control device 17 copies the light reception required time data and light reception intensity data from the rotational positions 0 ° to 180 ° stored in both areas A2 and B2 of the RAM to both areas A1 and B1, respectively ( S22 to S27).

  Thereafter, in the next one rotation, the control device 17 acquires the required light reception time data and the light reception intensity data between the rotational positions 0 ° to 180 ° in the same manner as described above (S9 to S12). It stores in each area of RAM A2 and B2 (S13-S16). Then, in the same manner as the previous operation, the control device 17 receives the required light reception time data and the received light intensity data for the rotation angle positions 0 ° to 180 ° in the current rotation stored in the regions A2 and B2 of the RAM, and the region. The light reception required time data and the light reception intensity data at the rotation angle positions 0 ° to 180 ° in the previous one rotation stored in A1 and B1 are compared.

  Thereafter, the comparison between the required light reception time data and the received light intensity data in the current rotation and the previous rotation is continuously performed for each subsequent rotation of the rotating mirror 11, and the received light intensity is the same at the same rotation angle position n. When the same number of times that the distance difference exceeds 30 cm is 5 or more, that is, E (n) is 5 or more, the control device 17 determines “YES” in S29, and proceeds to S32. In S32, the control device 17 determines that there is an influence of the laser beam output from another security device (determination means), and stops and restarts the motor 12 in the next S33 (restart processing means).

At this time, the control device 17 determines that the rotational angle position when E (n) is incremented, that is, the number of determinations that the laser beam emitted from the other security device B and reflected by the flange 24 is received is 5 or more. The restart of the motor 12 is controlled so as to achieve a constant rotational speed that is a control target at the rotational angle position of the motor 12 at that time.
By restarting the motor 12, it is possible to prevent the rotational angle positional relationship between the rotating mirrors 11 of the two security devices A and B from being influenced by the reflected light from the laser beam 24 on the other side.

As described above, according to the present embodiment, when the reflected light of the laser beam is received, it is possible to determine whether this is the reflected light of the laser beam emitted from another security device.
On the other hand, in the conventional case in which it is not determined whether or not the reflected light is a laser beam emitted from another security device (the steps S18 to S20 and S21 to S33 are not provided), the time required for light reception is the previous time and the current time. If there is a difference, it is determined that there is an intruder. Therefore, even if the reflected light of the laser beam emitted from another security device is received (one or more times), alarm processing for suspicious person intrusion (intruder Did not go there).
However, in this embodiment, even if the reflected light of the laser beam emitted from another security device is received, this can be determined, so that an alarm process is executed as an intruder exists even though there is no intruder. There is no fear.

  Further, in this embodiment, in S23, it is determined whether or not the consecutive misidentification frequency E (n) is the same value as E (n) in one rotation of the previous rotating mirror 11, and if it is the same value, E (n) is cleared to 0 (“YES” in S23, S24). The purpose of this is as follows.

  That is, for some reason, it is assumed that light from another light source that is not the laser light emitted from one security device and reflected by the ridge 24 is received at a certain rotation angle position n of the rotating mirror 11. Then, E (n) is incremented in S26. Thereafter, it is assumed that the rotation mirror 11 receives light from another light source again at the same rotation angle position n after one rotation or more. In this case, if it is assumed that the steps S23 and S24 are not provided, E (n) is further incremented and may eventually become 5 or more, and the restart process is executed. However, since this is caused by light from another light source that is not the laser light emitted from one security device and reflected by the ridge 24, it is not necessary to perform the restart process.

  On the other hand, in this embodiment, since S23 and S24 are provided, E (n) must be raised one by one every time the rotating mirror 11 makes one rotation, that is, from another light source. If the light is not continuously received for 5 or more rotations, the restart process is not performed. For this reason, it is not necessary to perform the restart process unnecessarily.

The present invention is not limited to the embodiment described above and shown in the drawings, and can be expanded or changed as follows.
The distance difference in S21 is not limited to 30 cm, and may be set to an appropriate value in consideration of the movement of a person in a stationary state and the difference in rotational speed between the two motors 12.
The restart of the motor 12 when E (n) becomes 5 or more is the rotational angle position of the motor 12 when it is emitted from the other security device, reflected by the flange 24 and received by one security device. It is not restricted to what controls it so that it may become a fixed rotational speed of a control target. Even if such control is not performed, if the system is restarted anyway, it is rare that the rotational angle positional relationship of the motor 12 is affected by the reflected light of the laser beam emitted from the counterpart security device. Therefore, it is possible to avoid the influence of the laser beam emitted from the security device on the other side.

The rotating mirror 11 may be configured not to be directly connected to the rotating shaft 12 a of the motor 12 but to reduce the rotation of the motor 12 and transmit it to the rotating mirror 11.
The semiconductor laser 9 may be configured to emit a laser beam in a pulse shape every time the motor 12 rotates 1 ° in the range of 0 ° to 360 °. However, only the reflected light of the laser beam emitted from the window 6a of the main body case 6 is a measurement target of the distance and the received light intensity.
The emission position of the laser beam is not limited every time the rotary mirror 11 rotates by 1 °, and the rotation angle position to be emitted may be any number of times.
E (n) may be a plurality of times and at least twice. Therefore, E (n) may be at least twice.

  In the drawings, 1 is a sensor unit, 2 is a processing unit, 7 is a laser beam emitting unit, 8 is a reflected light receiving unit, 9 is a semiconductor laser, 11 is a rotating mirror, 12 is a motor, 16 is a photodiode, and 17 is a control device. (Determination means) and 22 are a time measurement IC and a peak value detection circuit.

Claims (1)

A rotating mirror that is rotated by a motor, and each time the rotating mirror rotates by a predetermined angle, the laser beam is emitted toward the monitoring area, the emitted laser beam is reflected by an object, and the reflected laser beam is When entering the rotating mirror, the laser beam is reflected based on the rotation angle position of the rotating mirror when the laser beam is emitted and the time from when the laser beam is emitted until the reflected laser beam is received. In the security device that detects the direction of the object and the distance to the object,
When the laser beam is continuously received a plurality of times at the same rotation angle position in a plurality of rotations of the rotating mirror, the laser beam is emitted for the plurality of times of light reception until the reflected laser beam is received. When there is a change in time and the received light intensity of the reflected laser light does not change, there is provided a determination means for determining that the laser light emitted from another and reflected by the object is received instead of the laser light emitted by itself. A security device characterized by that.

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