JPS61282999A - Parked vehicle sensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a parked vehicle sensing device used for, for example, fee management using a parking meter or parking position management in a parking lot.

(Summary of the Invention) The present invention provides such a parked vehicle sensing device that is easy to install, avoids false detections caused by drivers, luggage, etc., and can accurately detect parked vehicles. This is how it was done.

(Prior art and its problems) Conventional parked vehicle sensing devices are generally employed to detect vehicles traveling on roads, and the following are known.

(i) First conventional example At or near the location where the vehicle is to be detected,
A loop coil is buried under the road surface, and changes in inductance as a metal vehicle approaches the loop coil are captured, and a vehicle detection signal is output based on a predetermined level change in the received current due to the inductance change. I was letting it happen.

(ii) At or near the location where the second conventional vehicle is to be detected,
An ultrasonic sensor consisting of a transmitter that projects ultrasonic waves and a receiver that receives reflected ultrasonic waves is installed to detect when ultrasonic waves are transmitted and received when reflected from the road surface and when reflected from parked vehicles. A vehicle detection signal was output based on the time difference between

However, the conventional example having such a configuration has the following drawbacks.

■Disadvantages of the first conventional example In order to accurately detect a vehicle using a loop coil, a large coil of about 2111X2+11 is usually required, and furthermore, this loop coil must be buried under the road surface. The road surface has no choice but to be cut over a wide area. For this reason, there is a drawback that cutting requires time and effort and construction costs are high.

- Disadvantages of the second conventional example There was a drawback that the detection accuracy for parked vehicles was reduced because it also sensed people such as drivers and luggage.

(Purpose of the Invention) The present invention has been made in view of the above circumstances, and is capable of detecting parked vehicles with simple installation work and avoiding false detections caused by drivers, luggage, etc. The purpose is to be able to perform this with high precision.

(Structure and Effects of the Invention) In order to achieve the above object, the present invention provides a transmission system in which a magnetic core is a magnetic body placed at one of two locations spaced apart from each other by a predetermined distance at or near a vehicle parking location. a reliable coil, a high-frequency oscillation circuit that outputs an excitation current to the transmitting coil, a receiving coil whose magnetic core is a magnetic material disposed at the other of the two locations, and a receiving coil that responds to level changes in the receiving current of the receiving coil. and an output circuit that outputs a parked vehicle presence signal in response.

According to this configuration, when an excitation current is output from the high-frequency oscillation circuit to the transmitting coil, a magnetic field is formed across the transmitting coil and the receiving coil, and a current is induced in the receiving coil by this magnetic field. When a vehicle enters a parking area, magnetic flux passes through the vehicle, lowering the magnetic resistance of the receiving coil, increasing the density of the magnetic flux interlinking the receiving coil, increasing the received current, or causing eddying. A level change occurs depending on whether the received current of the receiving coil decreases due to current loss. The presence of a parked vehicle can be detected based on changes in the level of

Therefore, the transmitting coil and the receiving coil are sufficiently smaller than conventional loop coils, and they only need to be installed at or near the vehicle parking area, and even if both coils are buried, However, the burial space required is small, the cutting work is simplified, the installation work is less labor-intensive, and construction costs are lower.

In addition, although magnetic vehicles have large changes in the level of received current, the level changes are small for non-magnetic people and cargo, making it possible to avoid false detections that occur with ultrasonic systems.
Parked vehicles can now be detected with high accuracy.

(Description of Examples) Hereinafter, the present invention will be described in detail based on examples shown in the drawings. FIG. 1 is a schematic configuration diagram of a parked vehicle sensing device according to an embodiment of the present invention, and FIG. 2 is a circuit diagram. In these figures, 1 is a transmitting coil wound around a magnetic material 1a such as ferrite as a magnetic core, and 2 is a receiving coil wound around a magnetic material 2a such as ferrite as a magnetic core. Yes, near the vehicle parking area,
They are arranged at two locations separated by a predetermined interval in the longitudinal direction of the parked vehicle 3. Both coils 1.2 and both magnetic bodies 1a, 2a are attached and supported at the upper end of the column 4, respectively.

5 is a main body housing an electric circuit section.

An excitation means 8 comprising a high frequency oscillation circuit 6 that outputs an excitation current and an amplifier circuit 7 that amplifies the excitation current is connected to the transmitting coil l.

The receiving coil 2 is connected to an output circuit 9 that outputs a parked vehicle presence signal in response to a change in the level of the received current. The output circuit 9 includes an amplifier 10, a bandpass filter 11, a detection circuit 12, and a determination section 13, and after amplifying the multiplier current from the receiving coil 2,
Suffi) Letter 11 (2) The noise component is removed, the detection circuit 12 detects the signal, and the signal is input to the determination section I3.
．． ). The determination unit 13 includes a switch circuit 14 , a first capacitor 15 connected to a first contact of the switch circuit 14 , and a second capacitor 15 connected to a second contact of the switch circuit 14 .
Capacitor 16 and first and second capacitors 15.1
6, a differential amplifier circuit 17 connected to each positive terminal, a comparator 18 connected to the output terminal of the differential amplifier circuit 17, and a constant voltage power supply 19 for determining a threshold voltage V ref of the comparator 18; The switch circuit 14 is provided with a timing circuit 20 that outputs a pulse signal C for switching the switch.

The timing circuit 20 is a comparator! When the output of the comparator 8 is at the "L" level, a pulse signal is output to the switch circuit 14, and when the output of the comparator 18 is at the "H" level, the output of the pulse signal is stopped. Further, the switch circuit 14 connects the detection circuit 12 to the first capacitor 15 when the pulse signal from the timing circuit 20 is at the "H" level, and vice versa.
The detection circuit 12 is configured to be connected to the second capacitor 16 when the signal is at the "level".

Next, the operation of this embodiment will be explained based on the time chart of FIG.

The excitation current from the high frequency oscillation circuit 6 is amplified by the amplifier circuit 7, and the excitation current excites the transmitting coil l, and as shown in FIG. 4(a), the transmitting coil l and the receiving coil 2
A magnetic field is formed between the two.

The reception current received by the reception coil 2 is amplified by the amplifier circuit 7, noise components are removed by the bandpass filter 11, and the signal a is detected by the detection circuit 12 to become a signal.

When the vehicle 3 enters the parking area and reaches the magnetic field, the timing circuit 20 outputs the pulse signal C to the switch circuit 14 from the time 1+ at which the vehicle 3 reaches the magnetic field until the time t, at which a minute amount of time has passed. 14 switchings are repeated. The first capacitor 15 is connected to the pulse signal C
is charged by the input signal d when is at “H” level,
The second capacitor 16 is charged by the input signal e when the pulse signal is at the "L" level. These input signals d and e are at the same level as the output signal of the detection circuit 12.

Since both the first and second capacitors I6 alternately repeat charging and discharging in response to switching operations, the charging voltage V of the first capacitor 15 and the charging voltage V of the second capacitor 16 are usually substantially different from each other. maintain an equal state.

By the way, as the vehicle 3 enters the parking area and reaches the magnetic field, the magnetic flux concentrates on the metal parts of the vehicle 3, as shown in FIG. The mutual inductance with 2 changes. That is, the amplitude of the output signal a of the bandpass filter 11 begins to increase, and the level of the output signal a of the detection circuit 12 also begins to increase accordingly. At this time, if the pulse signal C rises at time t and the detection circuit 12 is connected to the first capacitor 15, the level of the input signal d to the first capacitor 15 is the output from the detection circuit '12. The level of the output signal f of the differential amplifier circuit 17 rises by a very small amount in response to the rise of the signal f. However, since the increase in the output signal f is very small, the output signal f is lower than the threshold voltage V rer of the comparator 18, and the output signal g of the comparator 18 maintains the "L" level, and the parked vehicle presence signal is S is not output.

When the pulse signal C falls at time t and the detection circuit 12 is connected to the second capacitor 16, at this time the vehicle 3 has entered the magnetic field significantly, and the level of the output signal S of the detection circuit 12 is low. The level of the input signal e to the second capacitor 16 is sufficiently higher than the rise of the input signal d to the first capacitor 15, since rise significantly. Therefore, in the first capacitor 15, the charging voltage V is maintained constant, but in the second capacitor 16, the charging voltage V is changed depending on the level of the input signal e thereto.
That is, it changes upward in response to a change in the level of the output signal of the detection circuit 12. As a result, the output signal f of the differential amplifier circuit 17 also rises, and its level reaches the threshold voltage V r
ef is exceeded, and the converter 918 (7) output signal g becomes “H”.
As a result, the parked vehicle presence signal S is output to an external device (not shown), and the output signal g at the "H" level is input to the timing circuit 20.
The output of the pulse signal C from the timing circuit 20 is stopped.

When the vehicle 3 leaves the parking area and passes through the magnetic field, the level of the output signal of the detection circuit 12 decreases accordingly. As a result, the level of the output signal f of the differential amplifier circuit 17 reaches the threshold voltage V re at time t3.
When it becomes lower than f, the output signal g from the comparator 18 becomes "L" level, and the parked vehicle presence signal S is no longer output. Moreover, as a result of the output signal g becoming "L" level, the pulse signal C is outputted from the timing circuit 20 to the switch circuit 14, and switching is restarted.

As a result, the levels of the human input signals d and e to the first and second capacitors 15 and 16, respectively, become low corresponding to the level of the output signal S of the detection circuit 12, and the output signal R from the differential amplifier circuit 17 also becomes low. It stabilizes at “L” level.

The output signal from the detection circuit 12 is input to the amplifier circuit 7 of the excitation means 8, and the gain of the amplifier circuit 7 is automatically adjusted in response to the level of the output signal.

FIG. 5 is a plan view showing an example of use, and FIG. 5(a) is a
This shows a case where it is applied to a parking lot, and a transmitting coil 1, a receiving coil 2, and a main body 5 are installed at each parking location of each vehicle, and the parked vehicle presence signal S from these main bodies 5 is transmitted to a control device in a management room. 21, and is configured to display the location where the parked vehicle is located, for example, on a display device that displays the entire parking lot. Figure 5(b)
2 shows a case in which the parking meter 22 is applied to parking fee management, in which a transmitting coil 1, a receiving coil 2, and a main body 5 are installed at the end of a sidewalk 24 corresponding to the parking area 23. The vehicle presence signal S is input to the parking meter 22, and the parking meter 22 is activated when the vehicle is parked, and the parking meter 22 is automatically deactivated and reset as the vehicle leaves. is configured to do so.

According to the present invention, since the transmitting coil 1 itself is an active type that generates a magnetic field, it has the advantage of being less susceptible to external influences such as steel-framed buildings. It also has the advantage of being easy to handle when carrying out communication while supplying operating power to the communication device.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a parked vehicle sensing device according to an embodiment of the present invention, FIG. 2 is a circuit diagram, FIG. 3 is a time chart, and FIG.
The figures are schematic side views showing how the magnetic field is formed, with (a) showing a state without a vehicle and (b) showing a state with a vehicle. FIGS. 5(a) and 5(b) are schematic plan views each showing an example of use. DESCRIPTION OF SYMBOLS 1... Transmission coil, la... Magnetic material of the transmission coil, 2... Receiving coil, 2a... Magnetic material of the receiving coil, 3... Vehicle, 6... High frequency oscillation Circuit, 9... Output circuit, S...
Parked vehicle presence signal.

Claims (1)

[Claims] (1) A transmitting coil having a magnetic core made of a magnetic material disposed at one of two locations separated by a predetermined distance from each other at or near a vehicle parking location; and a high-frequency oscillation circuit that outputs an excitation current to the transmitting coil. A parked vehicle, comprising: a receiving coil having a magnetic core that is a magnetic material disposed at the other of the two locations; and an output circuit that outputs a parked vehicle presence signal in response to a change in the level of a received current of the receiving coil. Sensing device.