JP3135855B2 - In-vehicle microwave detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave detector for a vehicle which is mounted on a general automobile and generates an alarm to a driver when a predetermined microwave arriving from outside is detected. The present invention relates to a technique for preventing an unnecessary alarm from being generated during operation at a low speed.

[0002]

2. Description of the Related Art This kind of microwave detector for on-vehicle use includes:
As is well known, receiving circuit means for receiving and receiving microwaves arriving from the outside with an antenna, signal discriminating means for discriminating whether or not the received signal is a predetermined microwave signal, and Alarm means for generating an alarm output when a predetermined microwave signal is discriminated by the means. In this way, microwaves from radar for speed enforcement cracking are detected, and the driver is notified to encourage safe driving.

Therefore, when traveling at a sufficiently low speed, there is no need to generate an alarm even if microwaves are detected from the speed detection radar. Therefore, in some in-vehicle microwave detection devices, a vehicle speed signal is extracted from the electronic control system of the vehicle and input to the device, and based on the vehicle speed signal, when the traveling speed value is lower than the set value, the above alarm is generated. The function to control so as not to appear is added.

[0004]

It is not preferable in various senses to extract a vehicle speed signal from an electronic control system of a vehicle in order to prohibit an alarm output in a low-speed running state in a vehicle-mounted microwave detection device. . First, when extracting the vehicle speed signal from the complicated electronic control system of the car,
Improper wiring work can cause serious malfunctions in the electronic control system of the vehicle, so wiring work cannot be performed unless a specialized contractor with specialized knowledge is used. Therefore, the end user cannot utilize the unnecessary alarm prohibition function simply by purchasing this type of device and mounting it on his / her own vehicle, and has to ask a specialized contractor to perform installation work. In addition, some automobiles do not have a circuit configuration / wiring configuration for extracting a vehicle speed signal to the outside. In such an automobile, even if a professional company is requested, an unnecessary alarm prohibition function cannot be used.

SUMMARY OF THE INVENTION The present invention has been made in view of the above background, and has as its object to solve the above-described problems and allow an end user to make his own work without performing special wiring work by a specialist. An object of the present invention is to provide an in-vehicle microwave detection device which can utilize an unnecessary alarm prohibition function in a low-speed running state by simply being mounted on an automobile. Also,
Another object of the present invention is to provide a vehicle speed sensor suitable for such an in-vehicle microwave detection device and the like, which can detect a vehicle speed in a simple and independent system from a vehicle.

[0006]

In order to achieve the above-mentioned object, in a vehicle-mounted microwave detecting apparatus according to the present invention, a receiving circuit means for receiving and receiving a microwave arriving from the outside with an antenna, Signal discriminating means (corresponding to "microcomputer" in the embodiment) for discriminating whether or not the received signal is a predetermined microwave signal, and an alarm for outputting an alarm when the predetermined microwave signal is discriminated by this means. Means (corresponding to an "alarm circuit" in the embodiment), a magnetic sensor arranged in proximity to the wheel rotation mechanism and outputting a signal proportional to the rotation speed of the wheel, and a magnetic sensor based on the output of the magnetic sensor. To detect the running speed of the vehicle,
A control means (corresponding to a "microcomputer" in the embodiment) for prohibiting an output operation of the alarm means when the traveling speed value is lower than a predetermined set value; and a signal proportional to the rotation speed is: The detection signal is a detection signal of a magnetization pattern magnetized on the wheel.

[0007] Preferably, the vehicle-mounted microwave detecting device having the above-mentioned configuration includes parameter input means for appropriately setting a parameter for converting an output of the magnetic sensor into a running speed of the vehicle. 2) A speed set value input means for arbitrarily setting the set value of the traveling speed value for inhibiting the operation of the alarm means can be provided (claim 3).

[0008] Then, as the vehicle speed sensor for use in microwave detecting apparatus described above (the function of detecting the magnetic sensor + speed), for example, is arranged close to the rotating mechanism of the car wheels, the opposing wheel wear A magnetic sensor for detecting a change in a magnetic field accompanying rotation of the wheel based on the magnetized magnetization pattern; and speed detecting means for detecting a traveling speed of the vehicle from a change pattern of the magnetic field based on an output of the magnetic sensor. Ru can be configured Te.

As a more specific example, the speed detecting means detects a rotation cycle of the wheel by obtaining an autocorrelation function for a waveform based on an output signal of the magnetic sensor, and detects a rotation cycle of the wheel based on the autocorrelation function. Ru can be configured to which detects the running speed.

[0010] Incidentally, the car speed sensor described above, according to claim 1
Although it may be incorporated in a part of the on-vehicle microwave detection device specified in 3 above, it is not limited to this, and it is also possible to output vehicle speed information to another device. On the contrary, as an apparatus for determining the vehicle speed in an independent system for realizing claims 1 to 3, the above-mentioned apparatus can be suitably used. However, the present invention is not limited to this. Anything can be used as long as it satisfies the requirements of items 1 to 3.

That is, the wheels are magnetized, and
The state of magnetization is not uniform in the circumferential direction (rotational direction). Therefore, when the wheel rotates, the magnetic sensor facing the wheel detects a magnetic field based on the state of magnetization of the facing portion and outputs a signal corresponding to the strength, so that the output signal becomes a waveform signal. . In this waveform (change pattern), one rotation of the wheel is one cycle, and the one-cycle change pattern is repeatedly output. Therefore, the rotational speed of the wheels, that is, the vehicle speed can be obtained from the appearance of the change pattern.

[0012] Then, good simple and accurate, autocorrelation by obtaining the thereby be varied on the way the state of magnetization can be always extracted accurately one cycle. When the vehicle speed increases or decreases, the wheel rotation speed also increases or decreases.
The frequency of the magnetic field change pattern also increases or decreases. Therefore, the frequency can be obtained, and the speed can be detected from the frequency.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a schematic configuration of an on-vehicle microwave detecting device according to an embodiment of the present invention.
The reception signal of the antenna 1 is processed by the reception circuit 2 and input to the microcomputer 3. The microcomputer 3 performs a discrimination process on the signal from the receiving circuit 2 by a predetermined algorithm, and discriminates whether or not the received signal is a microwave signal from a radar used for speed regulation. When it is determined that a predetermined microwave signal has been received, a control signal is given to the alarm circuit 4 to generate an alarm notifying the driver of the fact. The alarm circuit 4 includes a buzzer and an LED lamp, and sounds and a lamp indicate that the vehicle is approaching the speed detection radar.

The above is the basic functional part of the microwave detector for vehicle use. On the other hand, a control system for prohibiting an unnecessary alarm in a low-speed running state is configured as follows.

According to the present invention, instead of performing wiring work for extracting a vehicle speed signal from an electronic control system of an automobile, a magnetic device which is disposed close to a wheel rotation mechanism and outputs a signal proportional to the rotation speed of the wheel is provided. The sensor 5 is used. As the magnetic sensor 5, for example, a flux gate type magnetic sensor can be used. The magnetic sensor 5 and a preamplifier 6 for amplifying the sensor output are both housed in a small package 7. The output of the preamplifier 6 is connected to a circuit section of the apparatus main body by a two-core shielded wire 8 having a length of about 3 meters.

The main body of the apparatus is installed near the driver's seat in the vehicle, and the sensor package 7 is disposed, for example, under the seat cushion of the rear seat and as close as possible to the rear wheel. By doing so, the rotation of the magnetized rear wheel is detected by the magnetic sensor 5, and the preamplifier 6 outputs a waveform signal according to the state of magnetization of the rear wheel.

A rotation detection signal (waveform signal) from the preamplifier 6 is guided to a circuit section of the apparatus main body through a two-core shielded wire 8,
Low-pass filter 9 and automatic gain control amplifiers 10 and A
The signal is processed by the / D converter 11 and input to the microcomputer 3.
Here, the low-pass filter 9 has a function of removing high-frequency noise components, and the frequency characteristic of the fluxgate type magnetic line has a mountain shape with a peak in a certain frequency band as shown in FIG. As shown by the solid line in the figure, the filter has a function of obtaining a substantially flat output in a wide frequency range as shown by a solid line in FIG.

FIG. 3 shows an example of a signal waveform finally input to the microcomputer 3. That is, as shown, a signal having a frequency proportional to the rotation speed of the wheel is output.

In the microcomputer 3, an autocorrelation function is obtained for a given signal waveform, and a waveform as shown in FIG. 4 is obtained. Thereby, the basic period T is known, and the basic period T is a waveform obtained by one rotation of the rear wheel.
Therefore, the speed V of the vehicle on which the present sensor is mounted is a value obtained by dividing a certain proportional coefficient by the basic period T, and by performing such an arithmetic processing, the current speed V of the vehicle can be obtained.

In a car, for example, when passing through a railroad crossing with a strong magnetic field, the magnetization distribution on the outer peripheral surface of the rear wheel may be changed. As an example, when the output waveform before the crossing is as shown in FIG. (A), the output waveform after the crossing is the same even though the vehicle travels at a constant speed of 50 km / h. different. However, if the rotation speed of the rear wheel is the same, the basic period T
Will be the same. Further, according to the same principle, if the wheels are the same, the basic period T is the same even if the magnetization distribution is different. Therefore, the speed V can be obtained regardless of whether or not the magnetization distribution of the rear wheel changes during traveling.

A numerical setting device 12 such as a DIP switch is provided as a parameter input means for appropriately setting a parameter (such as α) for converting the output of the magnetic sensor 5 into a running speed of the vehicle. It is connected to the. Then, appropriate parameters are set in the numerical value setting device 12 in accordance with the wheel diameter of the vehicle on which the present device is mounted.

With the above configuration, the microcomputer 3 determines the traveling speed of the vehicle from the frequency of the output signal of the magnetic sensor 5.
Further, the microcomputer 3 determines whether the obtained traveling speed value exceeds or falls below a predetermined set value. If the traveling speed value falls below the set value, the received signal from the receiving circuit 2 indicates a speed violation. Even if it is determined that the signal is a microwave signal from the radar used for the control, no drive control signal is output to the alarm circuit 4. This is the control system that prohibits the unnecessary alarm in the low-speed running state.

The set value of the traveling speed value at which the operation of the alarm means is prohibited is determined as follows. A setting switch 13 for that purpose is connected to the microcomputer 3. The vehicle is run at an appropriate speed, and the driver or assistant presses the setting switch 13 at an appropriate timing. Then, the microcomputer 3 writes the running speed value (the value calculated from the output of the magnetic sensor 5) at the time when the setting switch 13 is pressed into a predetermined nonvolatile memory, and sets the value as the set value.

In the above embodiment, A /
Although the D converter 11 is provided, the present invention is not limited to this. For example, a comparator may be used instead of the A / D converter. Then, for example, in the case of the signal waveform shown in FIG. 3, since a pulse signal as shown in FIG. 6 is generated, the microcomputer 3 may calculate the autocorrelation based on the pulse signal. With such a configuration, the cost can be reduced although the accuracy is lowered. In particular, in the case of the above-described microwave detection device, a specific speed is not determined, but a low speed / high speed is discriminated, and the boundary of the discrimination does not need to be very precise. In the case of a device, a device using such a comparator is also effective.

Further, in the above-described embodiment, the function for obtaining the auto-correlation function of the package 7, the low-pass filter 9, the automatic gain control amplifier 10, the A / D converter 11, and the microcomputer 3 and the vehicle speed based on the auto-correlation function shown in FIG. And a vehicle speed sensor according to the present invention.

An embodiment of an independent vehicle speed sensor can be configured as shown in FIG. 7, for example. That is, as is clear from the comparison with FIG. 1, the antenna 1, which is indispensable for the microwave detection function from the circuit configuration of FIG.
The display circuit 14 is provided in place of the alarm circuit 4 while eliminating the receiving circuit 2. Further, an output terminal 15 is provided. Other configurations are the same as those of the device shown in FIG. 1, and therefore, the same reference numerals are given and the detailed description is omitted.

With this configuration, the speed can be determined by detecting the rotation speed of the rear wheel based on a change in the magnetic field detected by the magnetic sensor 5 in accordance with the same principle as described above. Then, the determined speed can be output to the display unit 14 or the speed information can be output to another device via the output terminal 15. Note that the display unit 14
It is not necessary to provide both the output terminal 15 and the output terminal 15, and either one may be provided, and the output device is not limited to the display unit 14.

[0028]

As described above in detail, according to the present invention, it is not necessary to perform a special wiring work by a specialist to extract a vehicle speed signal from an electronic control system of an automobile, and a mechanism for extracting a vehicle speed signal. Even in a car that is not turned on, the end user can utilize the unnecessary alarm prohibition function in a low-speed running state simply by mounting it on his own car. Also, the vehicle speed sensor can detect one rotation of the axle from the change pattern of the magnetization distribution in the circumferential direction (rotation direction) of the axle, and can calculate the speed from the rotation.
With a simple configuration, the vehicle speed can be measured by an independent measurement system without receiving a signal from the vehicle.

[Brief description of the drawings]

FIG. 1 is a schematic configuration block diagram of an on-vehicle microwave detection device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating frequency characteristics of outputs of respective units.

FIG. 3 is a waveform chart showing an example of a sensor (low-pass filter) output in the embodiment device.

FIG. 4 is a diagram illustrating an autocorrelation function of the waveform signal of FIG. 3;

FIG. 5 is a diagram showing an example of an output waveform signal when the magnetization distribution of the wheels changes during traveling.

FIG. 6 is a diagram illustrating a modification.

FIG. 7 is a schematic configuration block diagram of an on-vehicle microwave detection device according to another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 antenna 2 reception circuit 3 microcomputer 4 alarm circuit 5 magnetic sensor 6 preamplifier 7 sensor package 8 2-core shielded wire 9 low-pass filter 10 automatic gain control amplifier 11 A / D converter 12 numerical setting device 13 setting switch

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) G01S ⁷ /00-7/42 G01P 3/487 G01R 29/08

Claims (3)

(57) [Claims] 1. A receiving circuit means for receiving a microwave arriving from the outside through an antenna, and a signal discriminating means for discriminating whether a received signal is a predetermined microwave signal, and a signal discriminating means. An alarm means for outputting an alarm when a predetermined microwave signal is discriminated by a magnetic sensor disposed close to a wheel rotation mechanism and outputting a signal proportional to the rotation speed of the wheel; Control means for detecting the traveling speed of the vehicle based on the output, and prohibiting the output operation of the alarm means when the traveling speed value is lower than a predetermined set value, wherein the signal proportional to the rotation speed is And a detection signal of a magnetization pattern magnetized on a wheel. 2. The on-vehicle microwave detecting device according to claim 1, further comprising parameter input means for appropriately setting a parameter for converting an output of the magnetic sensor into a running speed of the vehicle. . 3. The vehicle-mounted vehicle according to claim 1, further comprising a speed setting value input means for arbitrarily setting the set value of the traveling speed value for inhibiting the operation of the alarm means. Microwave detector.