JP3548776B2 - Vehicle detection device - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a vehicle, such as a passenger car or a truck, that passes through a predetermined route one by one.Vehicle detection device to detectAbout.
[0002]
[Prior art]
In recent years, with the proposal of non-stop toll booths that allow payment to be made through communication, development of a vehicle detection device for detecting vehicles approaching the toll booth one by one has been promoted. . 2. Description of the Related Art Conventionally, as this type of vehicle detection device, there is a vehicle detection device having a configuration in which a sensor unit having a light emitting and receiving unit and a regression reflection plate are arranged to face each other.
[0003]
FIG. 18 is an installation example of the vehicle detection device, in which a sensor unit 1 and a regression reflection plate 2 are provided to face each other across a road RD.
The sensor unit 1 includes a light emitting unit and a light beam scanning unit for scanning light generated by the light emitting unit as a light beam in a housing 1 ′ having a window (not shown) for transmitting and receiving light. , A light receiving unit for receiving the reflected light with respect to the light beam, a control circuit for detecting the vehicle, and the like.
[0004]
The regression reflection plate 2 functions as a reflection surface by arranging reflective optical elements such as prisms in a longitudinal direction along the length direction of the plate surface. 1 and is arranged in a state in which the length direction of the plate is aligned with the vertical direction.
[0005]
In the vehicle detection device having the above-described configuration, the light projecting unit emits light by being provided with a driving pulse at predetermined time intervals, and the light beam BM generated by the pulse emission is sequentially scanned and emitted to the regression reflection plate 2. This scanning is performed so as to spread in a fan shape in the length direction of the regression reflection plate 2. Each light applied to the regression reflection plate 2 is specularly reflected on the reflection surface, and the light received by the sensor unit 1 is received. Incident on the part.
[0006]
The example of FIG. 18 shows a state in which the vehicle 40 has not reached the scanning area of the light beam BM. In this case, the reflected light for each light applied to the regression reflector 2 is incident on the light receiving unit. , A detection signal indicating "no vehicle" is output from the control circuit. Thereafter, when the vehicle 40 moves forward and reaches the scanning area of the light beam BM, the light beam BM is shielded by the vehicle body, so that the amount of reflected light incident on the light receiving unit is drastically reduced. As a result, the control circuit determines that the vehicle 40 exists in the scanning area of the light beam BM, and outputs a detection signal indicating “vehicle present”.
[0007]
[Problems to be solved by the invention]
When the vehicle detection device having the above configuration is introduced into a tollgate on an expressway, two or more vehicles connected by a towbar must be detected as "one vehicle". Therefore, it is necessary to make the scanning interval of the light beam dense so that the detection signal of "vehicle presence" is output to each vehicle in series with the tow bar portion interposed therebetween. Furthermore, in order to remove erroneous detection due to noise such as dust and dust, the detection of “vehicle present” is performed in a state where the light beam is continuously shielded a plurality of times. It is necessary to make settings so that the beam light corresponding to the pulse is reliably irradiated.
[0008]
FIG. 19 shows an example in which the beam light BM for four pulses is applied to the traction rod 41 having a diameter of about 50 mm. The thickness of the beam light BM is set to 30 mm, and the irradiation position of this beam is shifted by 5 mm. Is set. By narrowing the scanning interval of the light beam in this way, the detection signal of “vehicle presence” is continuously output from the front traction drive vehicle to the rear traction vehicle, and the connected vehicle is It will be recognized as one vehicle.
[0009]
However, when the resolution of vehicle detection is increased in this manner, a problem occurs in that a vehicle whose cargo or the like protrudes from the vehicle main body is erroneously detected as a separate vehicle from the vehicle main body and the protruding portion.
[0010]
FIG. 20 is an example of the erroneous detection described above, and shows the side shape of the vehicle 40C to be detected and the presence / absence determination signal obtained for each part in association with each other. The determination signal indicates “vehicle present” in the on state and “no vehicle” in the off state. R in the figure_AIndicates a region in which the projected portion of the cargo can be irradiated with four light beams in the above-described light beam scanning region.
[0011]
In the case of the illustrated example, when the vehicle body passes through the inspection region R, the four beams of light do not hit the rear cargo 42, the vehicle detection state is released, and the detection signal changes from ON to OFF. However, after this, the region r_ASince the leading end portion of the cargo 42 enters the inside, the light beam is again shielded, and the detection signal returns to ON. Therefore, in this case, it is erroneously detected that two vehicles have passed.
The present inventionAt the time of vehicle detection, while accurately recognizing even small objects such as towbars, when a vehicle is not detected, small objects other than the vehicle body are not detected,A technical task is to realize high-precision vehicle detection.
[0012]
[Means for Solving the Problems]
In order to solve the above problems,The inventionIn this example, a detection area having a predetermined spread in the height direction is set from one side to the opposite side of the passage path of the vehicle, and the light beam is scanned with respect to this detection area along the height direction. Observe the shading condition ofWhen judgingWhen it is determined that there is a vehicle, the light-blocking state of the light beam is observed with finer accuracy than when it is determined that there is no vehicle.
[0013]
The vehicle detection device according to claim 1 isA beam light scanning means installed on one side of a passing path of a vehicle and scanning the beam light by pulse emission with a predetermined spread in a height direction toward the opposite side of the passing path; and a beam passing through the scanning area. A light receiving unit for receiving light, a determining unit for determining the presence or absence of a vehicle in a scanning area based on a light receiving state of the light beam by the light receiving unit; Scanning interval control means. Further, the scanning interval control means is configured to set a wider scanning interval while the determination means determines that there is a vehicle than when it is determined that there is no vehicle.
[0014]
Claim 2The vehicle detecting device according to the invention of the present invention includes the same light beam scanning means, light receiving means, and determination means as described above. The determining means in this case determines the presence or absence of a vehicle by observing the light receiving state of each light beam by a predetermined number in the scanning order of the light beams, and determines that there is no vehicle while determining that there is a vehicle. It is configured to execute the determination processing using the light receiving state for a smaller number of light beams than when the light beam is being transmitted.
[0015]
Claim 3The vehicle detection device according to the invention of the present invention includes the same light beam scanning means, light receiving means, and judgment means as in the invention of claim 2, and controls the power value of the light beam according to the judgment result by the judgment means. An optical power control unit is provided. Further, the light emission power control means is configured to set a lower light emission power value while the determination means determines that there is a vehicle than when determining that there is no vehicle.
[0017]
[Action]
Claim 1According to the invention, while the vehicle is being detected, the scanning interval of the light beams is set densely so that the light beams are surely applied even to a small object such as a towbar, and the presence of the vehicle is determined. Become so. On the other hand, while the vehicle is not detected, the scanning interval of the light beam can be set coarse so that the light beam does not hit the small object as described above, thereby preventing erroneous detection.
[0018]
Claim 2According to the invention, while the vehicle is being detected, the light receiving state is checked for every number of light beams corresponding to the small object such as the towbar, so that the small object is also accurately detected as a part of the vehicle. Is done. On the other hand, while the vehicle is not detected, the light receiving state is checked for each of a larger number of light beams than when the vehicle is detected, so that such a small object comes off the detection target.
[0019]
Claim 3According to the invention, when the vehicle is detected, the power value of the light beam is set lower than when the vehicle is not detected. Therefore, even if the light beam is blocked under the same condition, Is small when the vehicle is detected, and large when the vehicle is not detected. Therefore, even if the object is detected as a vehicle at the time of vehicle detection, the object is removed from the detection target when the vehicle is not detected.
[0020]
【Example】
FIG. 1 shows an example in which a vehicle detection device according to the present invention is installed at a position before a gate (not shown) of a tollgate.
In the drawing, 50A and 50B are concrete islands formed at positions before the gate, and the sensor unit 1 is embedded in one of the islands 50A.
[0021]
On the inner surface of the island 50A, a window (not shown) is opened corresponding to the buried position of the sensor unit 1, and the light beam BM from the sensor unit 1 is emitted from this window. On the other island 50B, a position facing the sensor unit 1 is cut out in the vertical direction to form a groove 51, in which the recursive reflection plate 2 faces the reflection surface toward the sensor unit 1 side. It is erected.
[0022]
FIG. 2 shows the configuration of the optical system of the sensor unit 1. In the figure, reference numeral 3 denotes a light projecting unit for generating a light beam to the regression reflection plate 2, which is composed of a light emitting element 6, such as an LED, a collimating lens 7, and a polarizing filter 8. Reference numeral 4 denotes a light beam scanning unit for scanning the light beam generated by the light projecting unit, and includes a galvanometer mirror 9 and a pulse motor 10 for sequentially changing the inclination angle of the galvanometer mirror 9. You. Reference numeral 5 denotes a light receiving portion for receiving the light beam reflected from the regression reflection plate 2, and includes a condenser lens 12 for condensing light and a polarizing filter 13 in front of a light receiving element 11 such as a photodiode. Deployed and configured.
[0023]
The light emitting element 6 of the light projecting unit 3 emits light at predetermined time intervals upon receiving a driving pulse from a modulation circuit described later. This light is collimated via a collimating lens 7, then polarized by a polarizing filter 8 to a predetermined wavelength, and guided to a galvanomirror 9. The galvanomirror 9 sequentially displaces the inclination in the vertical direction by the rotation of the pulse motor 10. Thus, the hourly light from the light projecting unit 3 is emitted as a beam light BM at different angles with respect to the length direction of the regression reflector 2.
[0024]
When the light beam BM is applied to the reflection surface of the regression reflection plate 2 in each scanning direction, the light is specularly reflected with the polarization plane rotated by 90 degrees due to the characteristics of the regression reflection plate 2. The reflected light enters the sensor unit 1 from a light emitting / receiving window (not shown), and is guided by the galvanomirror 9 in a direction parallel to the light emitting path.
[0025]
The light receiving unit 5 is provided at a position adjacent to the light projecting unit 3 on the path of the reflected light. The polarizing filter 13 on the light receiving unit 5 side is the same as that of the polarizing filter 8 on the light projecting unit 3 side, and is arranged with the azimuth orthogonal to the polarizing filter 8. Only the reflected light of the light beam BM from the regression reflector 2 is incident on the light receiving element 11, and the light receiving element 11 outputs a voltage signal corresponding to the amount of incident light.
[0026]
When the light beam BM is specularly reflected on a vehicle or the like, the specularly reflected light is also guided to the light receiving unit 5. However, since light hitting a metal part such as a vehicle body is reflected while maintaining the angle of the polarization plane, the polarization filter 13 blocks the reflected light from entering the light receiving element 11 to prevent erroneous detection. Can be.
[0027]
According to the optical system having the above-described configuration, the light projecting unit 3 and the light receiving unit 5 are disposed adjacent to the position below the galvanomirror 9, so that the optical system can be made compact and the sensor unit 1 can be downsized. be able to. Therefore, the sensor unit 1 can be buried in the concrete island 50A to make it inconspicuous, and a practical vehicle detection device can be provided.
[0028]
FIG. 3 shows the relationship between the installation state of the vehicle detection device and the detection area of the vehicle.
In the sensor unit 1, the light emitted from the light projecting unit 3 is sequentially swung up and down by the displacement of the galvanometer mirror 9, so that a fan-shaped scanning region R is set between the sensor unit 1 and the regression reflector 2. You. Therefore, by setting the angle θ between the upper limit and the lower limit of the light beam swing so that the amplitude of the light beam on the road is large enough to detect the vehicle, the scanning region R is detected by the vehicle. It will function as an area.
Note that r in the drawing corresponds to a passage area of a tow rod for connecting a tow vehicle.
[0029]
FIG. 4 shows an electric configuration of the vehicle detection device.
The sensor unit 1 includes, in addition to the optical system shown in FIG. 2, a modulation circuit 19 for generating a drive pulse for the light projecting unit 3, a scan driving unit 14 for driving the light beam scanning unit 4, A sine wave generation circuit 15, a comparator 16, a control circuit 17 for performing a vehicle detection process, and the like are incorporated. In the figure, reference numeral 1a denotes the above-mentioned light emitting / receiving window.
[0030]
The scanning drive unit 14 applies a driving pulse to the pulse motor 10 of the light beam scanning unit 4 to displace the galvanomirror 9 by a predetermined angle. The sine wave generating circuit 15 outputs a sine waveform signal having a cycle corresponding to one reciprocating operation of the galvanomirror 9, that is, one scanning period of the light beam BM. The pulse interval of the drive pulse is sequentially varied so that the hourly angular velocity varies according to the level of the sine waveform signal. In this case, the galvanomirror 9 is controlled so as to be fastest at the center position and to be slower as the vertical swing angle increases.
[0031]
A drive pulse is applied to the light emitting element 6 of the light projecting unit 3 at a fixed time interval from the modulation circuit 19, and the generated light is applied to the galvanomirror 9 via the lens 7 and the polarizing filter 8. You. By controlling the light projecting operation and the displacement operation of the galvanomirror 9 described above, the light beam BM is scanned at a finer interval from the center to the vertical direction as shown in FIGS.
[0032]
The light receiving unit 5 receives the reflected light of the emitted light from the regression reflector 2, and outputs a signal of a potential corresponding to the amount of the received light. This output signal is amplified by the amplifier 18 and then input to the comparator 16 where it is compared with a predetermined threshold value.
[0033]
An inverting circuit (not shown) is provided in the input path or the output path of the comparator 16, and the control circuit 17 outputs a signal of L level when the potential level of the received light exceeds the threshold value. Are below the threshold, H-level signals are input.
[0034]
The control circuit 17 includes a detection output stabilizing circuit 20, an off-delay timer 21, a scanning cycle measuring circuit 22, and the like. The detection output stabilizing circuit 20 includes a register for holding the comparison signal from the comparator 16 for a predetermined number of pulses (for example, four pulses), and outputs a signal H according to the level of the held four signals. Alternatively, an L-level signal is output.
[0035]
FIG. 5 shows the relationship between the comparison signal from the comparator 16 and the output signal from the detection output stabilizing circuit 20.
Each time a comparison signal is input from the comparator 16, the detection output stabilization circuit 20 checks the past four comparison signals including the comparison signal, and when all of them are at the H level (at time t1 in the figure). To raise the signal level to the H level.
[0036]
That is, this H level signal functions as a detection signal for recognizing an object having a size that blocks the four light beams BM, and the H level state is maintained until the next comparison signal is input. Is done. Therefore, when an H-level comparison signal is input continuously for four or more pulses, the detection output stabilizing circuit 20 continuously outputs an H-level detection signal. This detection signal falls when the comparison signal from the comparator 16 falls to the L level (time t2 in the figure).
[0037]
The scanning cycle measuring circuit 22 receives the sine waveform signal from the sine wave generating circuit 15 and measures one scanning period T of the light beam BM. The off-delay timer 21 outputs a signal that is at the H level for a predetermined period, triggered by the rise of the detection signal from the detection output stabilizing circuit 20. The H level period is the measured value of the scanning period. A period (T + α) that exceeds T by a predetermined time α is set.
The signal from the off-delay timer 21 serves as a final vehicle presence / absence determination signal. The H-level signal provides a “vehicle present” determination result, and the L-level signal provides a “vehicle absent” determination result. , Respectively.
[0038]
FIG. 6 shows the relationship between the detection signal and the determination signal.
Even if the detection signal from the detection output stabilizing circuit 20 falls within one scanning period T due to the function of the off-delay timer 21, the output of the H level is maintained for (T + α) from the rising of the first signal. The signal is maintained. Further, as shown in the drawing, if the detection signal is output again after the elapse of the period of (T + α), the output signal from the off-delay timer 21 is further maintained at the H level. It is possible to maintain the output signal of the H level over the period.
[0039]
Therefore, when the level of the received light with respect to the four continuous light beams BM becomes equal to or less than the threshold value by the detection output stabilizing circuit 20, that is, these four light beams BM are projected onto some object and the sensor unit If it does not return to the range of 1, it is determined that "there is a vehicle", and erroneous detection due to noise such as dust can be prevented. Further, even when the vehicle detection output of the detection output stabilization circuit 20 becomes intermittent, the off-delay timer 21 keeps the determination result of “vehicle present” for a period of (T + α).
[0040]
Normally, when the vehicle passes through the inspection area R, a state in which four or more light beams BM are blocked during one scanning period T continues for a plurality of scanning periods. Therefore, by the function of the off-delay timer 21, the determination signal of "vehicle present" can be continuously output to one vehicle, and a stable detection operation can be realized.
[0041]
Further, in this embodiment, in order to solve the problem shown in FIG. 20, the scanning interval of the light beam BM is changed according to the level of the determination signal from the off-delay timer 21. Here, the scanning interval is an interval between light beams one by one, and here, the modulation interval is used to vary the pulse interval of the driving pulse to the light projecting unit 3 so that the scanning interval is changed. Is made to fluctuate.
[0042]
FIG. 7A shows a specific configuration of the modulation circuit 19, and FIG. 7B shows its operation.
The modulation circuit 19 includes two comparators 23A and 23B, transistors 24A and 24B, a capacitor C, resistors R1-R6 for voltage division, a photocoupler 25, and the like.
[0043]
Capacitor C is power supply V_cc, And the divided potential Va from the connection line is input to the negative terminals of the comparators 23A and 23B. A reference potential V is provided on the + terminal side of each of the comparators 23A and 23B._REF, Divided potentials Vb and Vc are input. When the capacitor C is not charged, the potential Vd of the connection line is Vd_CCTherefore, the relationship of Va> Vb> Vc is established, and the outputs of the comparators 23A and 23B are both at the L level.
[0044]
The divided potential Va decreases as the capacitor C is charged, and when the capacitor C first decreases to Vb, the first comparator 23A is turned on to turn on the transistors 24A and 24B.
Further, the conduction of the transistor 24A increases the potentials of Vb and Vc so that Vc> Va, and the second comparator 23B is turned on. In addition, the conduction of the second transistor 24B causes the capacitor C to be discharged, and in response to this, Va gradually increases, and the outputs of the comparators 23B and 23A sequentially fall.
[0045]
Therefore, as shown in FIG. 7 (2), a drive pulse is output from the second comparator 23B to the light projecting unit 3 at predetermined time intervals due to a change in the potential Va based on charging and discharging of the capacitor C. Will be.
[0046]
On the other hand, the photocoupler 25 is rendered conductive by receiving the H-level determination signal from the off-delay timer 21. Since the resistance applied to the capacitor C is reduced by this conduction, the charging voltage of the capacitor C is increased, and the gradient of the change of the divided potential Va is steep. With this change, the time interval between the rise and fall of the drive pulse from the comparator 23B becomes smaller than when the photocoupler 25 is not conducting.
[0047]
Therefore, at the time of the determination that “there is a vehicle”, the output interval of the drive pulse from the modulation circuit 19 becomes short due to the conduction of the photocoupler 25. By providing the driving pulse with the short cycle to the light projecting unit 3, it becomes possible to set the scanning interval of the light beam BM more densely than at the time of the determination of "no vehicle".
By controlling the drive intervals of the light-emitting elements 6 in this manner, the average current flowing through the light-emitting elements 6 is much smaller than in the case where the light-emitting elements 6 are constantly driven at fine intervals, and the life of the light-emitting elements 6 can be extended.
[0048]
FIG. 8 shows an example of switching of the scanning interval of the light beam BM realized by the above-described circuit configuration. FIG. 8A shows the change of the light beam BM at the time when the "vehicle present" determination signal is output. FIG. 8B shows the scanning state of the light beam BM at the time when the “vehicle not present” determination signal is output.
[0049]
In the example of FIG. 8A, the detection interval with high accuracy is performed by making the pulse interval of the driving pulse small, and the scanning interval of the light beam BM in this case is shown in FIG. The same conditions as those described above, that is, conditions are set such that the four light beams BM surely pass through the passage area r of the towbar. Therefore, when a vehicle connected by a tow bar passes through the detection area R, the determination signal of “vehicle present” is continuously output to the tow bar.
[0050]
Conversely, in the example of FIG. 8B, the drive pulse interval is set wide so that the scan interval of the light beams BM is coarse, and the scan range r 'of the four light beams BM is the pulling rod. Is much larger than the passing area r.
In this case, the scanning interval of the light beams BM is such that the four light beams BM can be reliably projected on the body of a general passenger car, and an object smaller than the minimum size that the body can take is not detected. It is desirable to set as follows.
[0051]
According to the above configuration, when two vehicles connected by the tow rod 41 are to be detected, the front towing drive vehicle 40A enters the detection area R as shown in FIG. At this point, a determination signal indicating that "there is a vehicle" is output, and accordingly, the scanning interval of the light beam BM is switched from a coarse interval to a fine interval. Therefore, the four or more light beams BM surely hit the part of the middle tow rod 41, and the determination signal is kept at the “vehicle present” H level state until the succeeding tow vehicle 40B has passed. Will be.
[0052]
FIG. 9 (2) shows each signal when the vehicle 40C with the cargo 42 protruding rearward from the vehicle body is a detection target. Also in this case, similarly to the above, when the vehicle body enters the detection area R, a determination signal of "vehicle presence" is output, and the scanning interval of the light beam BM is switched to a fine interval at the time of "vehicle presence" determination. . Thereafter, an H-level determination signal of “vehicle present” is continuously output to the vehicle body, but when the vehicle body exits the detection area R, four or more light beams A state in which the BM does not hit occurs, and the determination signal is inverted to the L level of “no vehicle”. In response to this, the scanning interval of the light beam BM is also switched from the fine interval to the coarse interval, so that the determination signal is “no vehicle” even for the leading end portion of the cargo that was conventionally determined to be “vehicle present”. The L level is maintained.
[0053]
In the above embodiment, the scanning interval of the light beam BM is varied by controlling the light emission interval. However, the present invention is not limited to this, and the scanning interval of the light beam is varied by controlling the displacement speed of the galvanometer mirror 9. Is also good.
Further, the method for preventing one vehicle from being erroneously detected as a plurality of vehicles is not limited to the above-described method of controlling the scanning interval of the light beam. A method of changing the number of checks of the light blocking state of the reference light beam, and a method of changing a threshold value for determining that the light beam is in the light blocking state can also be adopted. Hereinafter, the configuration and operation of the vehicle detection device in which these methods are introduced will be described step by step.
[0054]
FIG. 10 shows an example in which the sensor unit 1 is configured to vary the number of light beams of the light beam BM serving as a reference for vehicle detection at that time in accordance with a determination signal indicating the presence or absence of a vehicle.
The control circuit 17 of the sensor unit 1 of this embodiment is provided with an on-delay timer 26 and two switch units 27 and 28 in addition to the same configuration as that of the first embodiment. Two signal paths are formed: a direct path 30A that directly connects the power supply and the off-delay timer 21, and a second path 30B with an on-delay timer 26 interposed therebetween.
[0055]
The configuration of the optical system and the drive system of the beam light operation unit 4 is the same as that of the first embodiment, and the detailed description is omitted here. The oscillation circuit 29 in the figure is different from the modulation circuit 19 of the first embodiment in that it is configured to output drive pulses at fixed time intervals. The time interval is set to be the same as that of the first embodiment when the “vehicle is present” is determined.
[0056]
The switches 27 and 28 operate in response to the determination signal from the off-delay timer 21. When the H-level determination signal of "vehicle present" is output, both switches 27 and 28 are connected to the direct path 30A. Is done. As a result, the detection signal from the detection output stabilizing circuit 20, that is, the detection signal indicating that "there is a vehicle" when the four or more light beams BM are continuously shielded is maintained as it is.
[0057]
On the other hand, when the determination signal is in the L level state of "no vehicle", each switch unit 27, 28 is connected to the second path 30B side. The on-delay timer 26 delays the rise timing of the detection signal from the detection output stabilizing circuit 20 by a predetermined period, thereby delaying the detection signal by the delay time and shortening the detection signal by the delay time. Output.
[0058]
For example, when a delay time corresponding to six light emission pulses is set, the detection signal is enabled as an H level when the state of the H level continues for 10 pulses or more, and the detection signal when the H level is 10 pulses or less is detected. The signal is invalidated.
[0059]
FIG. 11 shows the timing of each part in the control circuit 17 when the vehicle 40C shown in FIG. 9 (2) passes through the detection area R. In the drawing, the connection state of the switch units 27 and 28 indicates “off” when each of the switch units 27 and 28 is connected to the first direct path 30A, and is connected to the second path side 30B. Is indicated as “on”.
[0060]
When it is determined that "there is no vehicle", the switches 27 and 28 are connected to the second direct path 30B, and the on-delay timer 26 functions effectively. As in the first embodiment, the detection output stabilizing circuit 20 outputs a detection signal in response to the continuous input of the H-level signal to the control circuit 17 for four or more pulses (T in the figure).₁At the time).
[0061]
In response to the rise of this detection signal, the on-delay timer 26 is activated, and a period T for six light emission pulses is set._DLTime until elapses. And this period T_DLTime T has elapsed₂If the detection signal is still at the H level, the detection signal is validated at that time and the H-level signal rises.
[0062]
The off-delay timer 21 processes the validated detection signal in the same manner as described above and outputs a "vehicle present" determination signal. As a result, the switches 27 and 28 are switched to the direct path 30A side, and the detection signal from the detection output stabilizing circuit 20 is directly input to the off-delay timer 21.
[0063]
Thereafter, the "vehicle present" is determined when four or more light beams BM are continuously blocked, but the detection signal falls off after the vehicle body has passed.(T in the figure ₃ At the time)The set time (T + α) of the off-delay timer 21 isAfter that, the judgment signalIt is inverted to the L level of "no vehicle". In response to this, each switch unit is switched to the second path 30B side, and the on-delay timer 26 again functions effectively.
[0064]
Next, when the detection signal rises again, for example, when four light beams BM hit the portion of the cargo 42 protruding from the vehicle body (time T).₄At the time point), the on-delay timer 26 operates in the same manner as described above, and the delay time T_DLThe detection signal is suspended until elapses. At this time, as shown in the illustrated example, the delay time T_DLHas elapsed (T in the figure)₅If the detection signal has already fallen at the time point), the detection signal is invalidated, and the determination signal from the off-delay timer 21 is maintained at the L level indicating "no vehicle".
[0065]
FIGS. 12 (1) and 12 (2) show the accuracy of the detection processing in comparison with the case of "vehicle presence" and the case of "vehicle absence". Note that, in the drawing, r1 and r2 indicate regions including the necessary number of light beams BM for determining the presence or absence of a vehicle based on the detection signal.
[0066]
If "vehicle present" is determined, the detection signal is passed as it is, so that the presence or absence of a vehicle is checked for each of the four light beams BM as shown in FIG. Even for a small object such as a towbar, the determination signal of "vehicle present" can be continuously output. On the other hand, if it is determined that there is no vehicle, the delay time T_DLIf the time for six light emission pulses is set as, the number of continuous light-shielding of the light beam BM, which is a condition for raising the detection signal, is increased from four times to ten times, as shown in FIG. Then, the presence or absence of the vehicle is checked every 10 light beams. Therefore, small objects, such as towbars and projecting parts of the cargo, will be displaced from the detection target.
[0067]
FIG. 13 illustrates a configuration of the sensor unit 1 according to the third embodiment.
In this embodiment, the reflected light amount of the beam light serving as the vehicle detection means is varied between the time of "vehicle presence" and the time of "vehicle absence" determination. A light emitting current control circuit 31 is provided between the light emitting device and the circuit 29. The control circuit, the optical system, and the drive system of the beam light operation unit 4 all have the same configuration as that of the first embodiment.
[0068]
FIG. 14 shows a specific configuration of the light emitting current circuit 31.
In the figure, a light emitting element 6 composed of an LED has a driving transistor on the anode side.33And one of the two resistors R1 and R2 is connected to the cathode side via the switch unit 32. The switch section 32 is switched in accordance with the level of a determination signal from the off-delay timer 21. The switch section 32 is connected to the resistor R1 when "no vehicle" is determined, and to the resistor R2 when "vehicle is present". Is done.
Note that a resistor having a larger resistance value than the first resistor R1 is used as the second resistor R2.
[0069]
When the transistor 33 is turned on by receiving a driving pulse from the oscillation circuit 29,The light emitting element 6The light is emitted by the charging voltage of the capacitor 34, and the light emission power changes depending on which resistor R1 or R2 is connected to the light emitting element 6 at this time. That is, when the light emitting element 6 is connected to the first resistor R1 having a small resistance value at the time of the "vehicle absence" determination, a larger current flows than when the light emitting element 6 is connected to the resistor R2, and a light beam having a large power is emitted. be able to.
[0070]
FIG. 15 shows a state in which a part of the light beam BM is shielded by the presence of some object.
In each of the determinations of “vehicle present” and “vehicle not present”, assuming that a part of the light beam BM is shielded in the state as shown in the illustrated example, in any case, the sensor unit 1 The reflected light of the same ratio returns to the irradiation amount of the light beam BM at the time. However, the power value of the reflected light is larger at the time of “vehicle absence” determination where the strong light beam is applied than at the time of “vehicle presence” determination where the weak light beam is applied.
[0071]
FIG. 16 shows an output waveform from the light receiving element 11 when reflected light corresponding to one light beam BM is incident on the light receiving unit 5. Note that TH in the figure is a threshold value set in the comparator 16.
[0072]
At the time of the determination of "there is a vehicle", the level of the reflected light returning to the light receiving section 5 becomes lower than the threshold value TH even if the light is slightly blocked because the power of the original light beam is weak. Therefore, in this case, the comparator 16 outputs an H-level comparison signal indicating “there is a vehicle”.
[0073]
On the other hand, at the time of the determination of “no vehicle”, the light beam level of the main body is strong even though the light beam is blocked at the same rate. Reflected light enters. Therefore, in this case, the comparison output from the comparator 16 is at the L level, and the determination signal is maintained as "no vehicle".
At the time of “vehicle absence” determination, as shown in FIG. 17, it is desirable to set a light projection level such that the power value of the received light amount falls below the threshold value only when the light beam is completely blocked.
[0074]
Therefore, the light blocking state of the light beam BM with respect to the smallest detection target such as a tow bar is sampled, and the irradiation level of the light beam at each determination is set so that a remarkable difference occurs in the reflected light level at each determination. For example, the level of the detection signal for the detection target can be changed at each determination, and the size of the detection target at each determination becomes different.
[0075]
In this embodiment, the light emission power of the light projecting unit 3 is controlled in accordance with the level of the determination signal. Instead, two threshold values are set in the comparator 16 for each determination. Alternatively, the threshold value to be compared may be switched according to the level of the determination signal.
[0076]
In this way, a small object such as a tow bar can be detected by performing a detailed detection process when the “vehicle is present” is determined, while the detection accuracy is coarsened when the “no vehicle” is determined, and is smaller than the vehicle body. If the object is removed from the detection target, the number of vehicles can be counted accurately both when two vehicles are connected by a connecting rod and when luggage etc. protrude to the rear of the vehicle. Thus, a practical vehicle detection device can be provided.
[0077]
The embodiments described above can be implemented not only alone but also in combination with each other. In each of the embodiments, the control circuit 17 for vehicle detection is configured by hardware. However, the same operation as the circuit can be realized by a microcomputer.
[0078]
Further, each of the above embodiments is an apparatus for detecting a vehicle on a road, but the present invention is not limited to this, and the same configuration can be applied to a vehicle such as a train.
[0079]
【The invention's effect】
The present invention, as described above, scans light beams along the height direction from one side to the opposite side of the vehicle passage path, observes the light blocking state of each light beam, and determines the presence or absence of the vehicle When the vehicle is determined to be present, the light-blocking state of the light beam is observed with higher precision than when it is determined that the vehicle is not present. While the vehicle is recognized with high accuracy, small objects other than the vehicle body are not detected when the vehicle is not detected, so that each vehicle can be detected with high accuracy.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an installation example of a vehicle detection device according to the present invention.
FIG. 2 is a perspective view illustrating a configuration of an optical system of a sensor unit.
FIG. 3 is a front view illustrating a relationship between an installation state of the vehicle detection device and a detection area.
FIG. 4 is a block diagram illustrating a configuration of a vehicle detection device.
FIG. 5 is a timing chart showing a relationship between a comparison signal and a detection signal based on a light receiving level of reflected light.
FIG. 6 is a timing chart showing a relationship between a detection signal and a final determination signal.
FIG. 7 is a circuit block diagram and a timing chart showing a specific configuration and operation of the modulation circuit.
FIG. 8 is an explanatory diagram illustrating an example of a change in a scanning interval of a light beam.
FIG. 9 is an explanatory diagram showing a detection operation of the vehicle.
FIG. 10 is a block diagram illustrating a configuration of a vehicle detection device according to a second embodiment.
FIG. 11 is a timing chart showing a detection operation in the control circuit.
FIG. 12 is an explanatory diagram showing an example of a change in vehicle detection accuracy.
FIG. 13 is a block diagram illustrating a configuration of a vehicle detection device according to a third embodiment.
FIG. 14 is a circuit block diagram showing a specific configuration of a light emitting current control circuit.
FIG. 15 is an explanatory diagram illustrating an example of a light blocking state of a light beam.
FIG. 16 is an explanatory diagram illustrating an output signal from a light receiving element that has received reflected light of a light beam.
FIG. 17 is an explanatory diagram showing an example of a light-shielded state serving as a criterion for determining that there is no vehicle.
FIG. 18 is a front view showing an example of installation of a conventional vehicle detection device.
FIG. 19 is an explanatory diagram showing a specific example of irradiating a tow bar with four light beams.
FIG. 20 is an explanatory diagram showing an example in which a malfunction has occurred in vehicle detection.
[Explanation of symbols]
BM beam light
R inspection area
1 Sensor section
3 Emitter
4 Beam light scanning unit
5 Receiver
17 Control circuit
19 Modulation circuit
26 On-delay timer
31 Current control circuit for light emission

Claims (3)

Light beam scanning means installed on one side of the passage of the vehicle and scanning the beam light by pulse emission with a predetermined spread in the height direction toward the opposite side of the passage,
Light receiving means for receiving the light beam passing through the scanning area,
Determining means for determining the presence or absence of a vehicle in a scanning area based on a light receiving state of the light beam by the light receiving means;
Scanning interval control means for setting the scanning interval of the light beam according to the determination result by the determination means,
The vehicle detection device, wherein the scanning interval control means sets a smaller scanning interval during the time when the determination means determines that there is a vehicle than when it is determined that there is no vehicle. Beam light scanning means installed on one side of the passage path of the vehicle and scanning the light beam by pulse emission with a predetermined spread in the height direction toward the opposite side of the passage path,
Light receiving means for receiving the light beam passing through the scanning area,
Based on the light receiving state of the light beam of the light receiving means, comprising a determination means for determining the presence or absence of a vehicle in the scanning area,
The determination means determines the presence or absence of a vehicle by observing the light receiving state of each light beam by a predetermined number in the scanning order of the light beams, and determines that there is no vehicle while determining that there is a vehicle. A vehicle detection device that performs a determination process using a light receiving state for a smaller number of light beams. Light beam scanning means installed on one side of the passage of the vehicle and scanning the beam light by pulse emission with a predetermined spread in the height direction toward the opposite side of the passage,
Light receiving means for receiving the light beam passing through the scanning area,
Determining means for determining the presence or absence of a vehicle in a scanning area based on a light receiving state of the light beam of the light receiving means,
A projection power control unit that controls a power value of the light beam according to a determination result by the determination unit,
A vehicle detection device, wherein the light emission power control means sets a lower light emission power value while the determination means determines that there is a vehicle than when it is determined that there is no vehicle.

Images