JP2000025541A - Antenna device, and alarm system for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alarm system for automobile which is capable of surely detecting a person behind an automobile and giving an alarm, and an antenna device suitable for the alarm system for automobile. SOLUTION: The transmitted radio wave from a transmitter 13 possessed by a person 12 is received by an antenna 15 installed on an electrically grounded rear gate of a truck 14, a receiving device 16 demodulates the received ID code from the received signal, the receiving device collates the demodulated signal with a stored ID code, and only when both ID codes are agreed with each other, and the received signal is on not less than a specified level, an alarm signal is outputted to an alarm device 17, and an alarm sound is given to a driver of the truck 14. The person behind the truck 14 can be surely detected, and an alarm can be given thereby.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna device and a vehicle alarm system for a vehicle alarm system for detecting a case where a person is behind a vehicle and issuing an alarm to a driver.

[0002]

2. Description of the Related Art Conventionally, as an alarm system for a vehicle, a system using ultrasonic waves or infrared rays has been proposed.

In an alarm system using ultrasonic waves, for example, an ultrasonic wave emitted from an ultrasonic wave generator installed at the rear of an automobile is reflected by a human body located within a reachable range of the ultrasonic waves, and the reflected light is reflected by a human body. Ultrasonic sensors, also located at the rear of the car, detected the waves and detected that a person was behind the car, alerting the driver and alerting the driver.

In an alarm system using infrared rays, a person is located behind the automobile by detecting an infrared ray emitted by a human body located within a range where infrared rays can be detected by an infrared sensor installed at the rear of the automobile. The driver was alerted and alerted the driver.

[0005]

However, in the case of the ultrasonic system, an alarm may be issued even if there is not only a person but also an object in the detection range of the ultrasonic sensor. In addition, the ultrasonic waves emitted from the ultrasonic generator and returning to the ultrasonic sensor are not limited to those directly reflected by the human body and returned, and the reflected waves from other objects, the ground, walls, etc. are similar. In some cases, the ultrasonic sensor may detect the alarm and issue an alarm even when there is a person outside the predetermined detection range behind the vehicle. Further, other ultrasonic noises may be detected and an alarm may be issued by mistake.

In the infrared system, if there is an object or the like between an infrared sensor installed at the rear of an automobile and a person, infrared rays emitted from the human body are not correctly detected, and a person is present in a range where an alarm should be issued. In some cases, no alarm was issued. Further, there is a problem that the detection error increases when the ambient temperature fluctuates.

The present invention has been made by focusing on the problems existing in the prior art as described above. Its purpose is to reliably detect a person behind the car and issue a warning alarm system for vehicles, and
An object of the present invention is to provide an antenna device suitable for defining a detection range of a person by the vehicle alarm system.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, there is provided an antenna and an antenna device using a structural member of an automobile as a ground plane of the antenna. And

In such a configuration, since the structural member of the automobile functions as the ground plane of the antenna, the antenna can easily have directivity only on the side facing the structural member as the ground plane. .

According to the second aspect of the present invention, there is provided a transmitting device having a function of transmitting a signal radio wave of a specific frequency, the antenna device of the first embodiment receiving the signal radio wave of the specific frequency, and the antenna device. Receiving means having a function of detecting a signal from the signal radio wave of the specific frequency and outputting a warning signal when the voltage level of the signal is equal to or higher than a predetermined value, and issuing an alarm when receiving the warning signal The gist is to provide an alarm means.

[0011] In such a configuration, the antenna device receives the signal radio wave emitted from the transmitter, and the receiving device connected to the antenna device transmits the alarm signal when the signal radio wave is at a predetermined level or more. Emitted to the alarm device,
Since the alarm device issues an alarm, a transmitter within a predetermined sensitivity range of the antenna device can be detected, and the driver can be alerted.

According to a third aspect of the present invention, in the second aspect of the present invention, the transmitting device has a function of including an authentication code in a signal radio wave transmitted by the transmitting device, and the receiving means includes:
A storage device capable of storing a plurality of the authentication codes, wherein the reception unit outputs a warning signal when the code stored in the storage device matches the authentication code detected by the reception unit. The gist is that it has.

[0013] In such a configuration, in addition to the function of the invention of claim 2, the transmitter within the predetermined sensitivity range of the antenna device is detected without being affected by noise or erroneous signal, and the driver is notified. You can call attention.

According to a fourth aspect of the present invention, in the second or third aspect, the receiving means outputs an alarm signal corresponding to a reception voltage level of the signal radio wave emitted by the transmitting device. The point is that it has a function.

In such a configuration, in addition to the effect of the second or third aspect of the present invention, the receiving means can output an alarm signal corresponding to the received voltage level, so that the detection range in which an alarm should be issued is limited. It will be adjustable.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, in a vehicle alarm system 11 of the present embodiment, a transmitter 13 as a transmitting device carried by a person 12 and a rear part of a truck 14 as a vehicle are provided and emitted by the transmitter 13. Antenna 15 as an antenna device for receiving a signal radio wave, receiving device 16 as a receiving device, and alarm device 1 as an alarm device for issuing an alarm to a driver
7 is comprised.

As shown in FIG. 2, the antenna 15 is disposed on a rear tilt 18 as a structural member of an automobile made of a conductive metal at a rear portion of the truck 14, and an element 19 of the antenna 15 is arranged horizontally with respect to the ground. And rear tilt 18
Is held by the support member 20 so as to be horizontal. Element 19 of the antenna 15 and rear tilt 1
The distance to the antenna 8 is about 1/10 or less of the wavelength with respect to the frequency of the radio wave transmitted by the transmitter 13. The length L of the element 19 is one half of the wavelength, and the rear tilt 18 is longer. The rear tilt 18 is electrically grounded. By providing the antenna 15 as described above, an antenna directivity 21 as shown in FIG. 2 is obtained. That is, by using the rear tilt 18 of the antenna 15, it is possible to obtain sensitivity only behind the track 14.

The transmitter 13 is carried by a person 12 around the truck 14. With the transmitter 13,
The ID code as the authentication code is modulated at a specific frequency, and a signal wave is transmitted. Since the transmitter 13 includes an omnidirectional antenna (not shown), radio waves are radiated in all directions. Therefore, the signal wave emitted by the transmitter 13 is received by the antenna 15 only when the person 12 having the transmitter 13 is behind the truck 14.

Next, the receiving device 16 will be described. FIG.
As shown in FIG.
, A receiving circuit 31, a memory circuit 32 as a storage device, a signal processing circuit 33, and a registration switch 34.
It is composed of

The receiving circuit 31 is connected to the antenna 15 and receives a signal radio wave of a specific frequency transmitted from the transmitter 13 and arriving only from behind the truck 14. The receiving circuit 31 demodulates the ID code from the received signal, and demodulates the ID code.
A D code (hereinafter, reception ID code) 35 is output.

The reception circuit 31 outputs a voltage value corresponding to the voltage level of the received signal as a reception level signal 36. For example, when the transmitter 13 approaches the antenna 15 and the level of the received signal becomes the highest, the received level signal 35 is set to a maximum voltage of 5 volts, and as the transmitter 13 moves away from the antenna 15, the level of the received signal becomes higher. Is set so that the reception level signal 36 also becomes smaller in proportion to this.

Further, in the memory circuit 32, a plurality of ID codes and threshold voltages are stored as digital data. Both data are stored in the signal processing circuit 33.
Is read as appropriate.

The signal processing circuit 33 includes a read circuit for reading a plurality of ID codes and threshold voltage values stored in the memory circuit 32 from the memory circuit 32, and an ID code and a threshold level stored in the memory circuit 32. , An A / D conversion circuit for converting the reception level signal into a digital signal, and a central processing circuit (hereinafter referred to as C) for controlling these circuits and processing data.
PU) and the like (not shown).

The CPU has a collation function for collating the ID code read from the memory circuit 32 with the reception ID code 35 inputted from the reception circuit 31, and a CPU for retrieving the reception level signal 36 from the memory circuit 32. It has a comparison function of comparing the output threshold level data, a determination function of outputting an alarm signal 37 with reference to the output results of the comparison function and the comparison function, and the like.

The alarm device 17 receives an alarm signal 37 output from the signal processing circuit and issues an alarm sound to a driver. Next, the operation of the vehicle alarm system 11 will be described with reference to FIGS.

When the person 12 carrying the transmitter 13 enters the receivable range of the antenna 15, the antenna 15
Receives a radio wave transmitted from the transmitter 13. The receiving circuit 31 demodulates the ID code from the received signal and outputs the received ID code 35 to the signal processing circuit 33 as a digital signal. Also, a reception level signal 36 corresponding to the voltage level of the reception signal is output to the signal processing circuit 33 at the same time.

The signal processing circuit 33 includes the receiving circuit 3
When the receiving ID code 35 is received from 1, the reading circuit reads a plurality of ID codes stored in the memory circuit 32, and the CPU sequentially compares the ID code with the receiving ID code 35. The CPU temporarily holds the logic signal 1 when both ID codes match, and temporarily holds the logic signal 0 when they do not match.

Further, in the signal processing circuit 33,
The A / D conversion circuit converts the reception level signal 36 received from the reception circuit 31 into a digital signal and outputs the digital signal to the CPU. When receiving the digitized reception level signal, the CPU reads the threshold level data stored in advance from the memory circuit 32 and compares it. When the CPU determines that the reception level signal is larger than the threshold level data, the CPU holds the logic signal 1, and when the CPU determines that the reception level signal 36 is equal to or smaller than the threshold level data, it temporarily holds the logic signal 0. .

Based on the above signal processing, the CPU
Outputs an alarm signal 37 when it is determined that the reception ID code 35 matches the ID code stored in the memory circuit 32 and that the reception level signal 36 is larger than the threshold level data. . That is, the CPU
Means that the person 12 having the transmitter 13
It is determined that it is within a predetermined range behind by four. Note that the reception ID code 35 matches the ID code stored in the memory circuit 32 and the reception level signal 3
When 6 is equal to or smaller than the threshold level data, the CPU determines that the person 12 holding the transmitter 13 is outside the predetermined range behind the truck 14 and does not output the alarm signal 37. When the reception ID code 35 does not match the ID code stored in the memory circuit 32 and the reception level signal 36 is larger than the threshold level data, the CPU receives the erroneous signal. Is determined, and the alarm signal 37 is not output. Further, the reception ID
The code 35 is the ID stored in the memory circuit 32
When the code does not match and the reception level signal 36 is lower than the threshold level, the CPU does not output the alarm signal 37.

As described above, when the alarm signal 37 is output from the CPU, the alarm device 17 emits an alarm sound, so that the driver is notified that the person 12 is within a predetermined range behind the truck 14. I can judge.

Next, the adjustment of the detection range of a person behind the truck 14 in the vehicle alarm system will be described. In FIG. 3, the receiving device 16 is set to be switched to the registration mode by pressing the registration switch 34 for 5 seconds. Next, in the registration mode state, the transmitter 13 is held on the boundary of the range for detecting a person behind the truck 14 to output a signal radio wave. The receiving device 16 receives the signal radio wave, and receives a reception ID code 35
When the ID matches the ID code stored in the memory circuit 32, the reception level signal 36 is converted into a digital signal by the A / D conversion circuit in the signal processing circuit 33, and the digital data is transmitted to the memory circuit 32. Remember. The above operation is performed a plurality of times on the boundary of the detection range, and the value at which the reception level signal 36 becomes smallest is stored in the memory circuit 32 as threshold level data. That is, the receiving device 16 checks the ID code transmitted by the transmitter 13 from a signal wave received from a predetermined range behind the truck 14 and, when the reception level signal 36 is larger than the threshold value, issues an alarm signal. 37 can be output. Therefore, the detection range behind the truck 14 of the vehicle alarm system 11 can be adjusted.

Next, FIG. 4 shows the measurement results of the working distance of the warning system for an automobile using a real vehicle. The origin is set at the horizontal center of the rear tilt 42 disposed on the loading platform 41 of the truck 40, and an antenna (not shown) installed at the center of the rear tilt 42 receives the transmission wave of the transmitter with respect to a specific threshold level. Then, the area behind the truck 40 where the receiving device outputs the alarm signal was evaluated. As a result, the receiver output an alarm signal at a plurality of measurement points 43 shown in FIG. In other words, it was found from this evaluation that the vehicle warning system can detect a person behind the truck 40 in the hatched detection range 44. According to the present embodiment configured as described above, the following effects can be obtained.

(1) By using the rear tilt 18 fixed to the ground potential, the antenna 1 can be easily mounted.
5 can have unidirectionality. (2) Since the antenna 15 has unidirectionality,
The detection range can be easily set behind the track 14.

(3) Since the person 12 around the truck 14 has the transmitter 13 and detects the radio wave transmitted by the transmitter 13, the person 12 can reliably detect the radio wave even if there is an obstacle. Can be detected.

(4) ID code of the transmitter 13;
Since the ID code stored in the receiving device 16 is collated with the ID code, the alarm does not malfunction due to an erroneous signal or noise. (5) Since the threshold level for comparison with the reception level signal 36 can be changed, the detection range can be adjusted.

The present embodiment may be modified as follows. In the embodiment, the antenna 15 is provided on the track 14 side,
Although the case where the receiving device 16 and the alarm device 17 are provided and the transmitter 12 is provided on the person 12 side is shown, the antenna and the transmitter are provided on the truck 14 side, and the receiving device and the alarm device are provided on the person 12 side. You may. In this case, when a person having the receiving device and the alarm device enters a predetermined electric field of the antenna installed in the vehicle, the alarm device issues an alarm to the person, and indicates that the truck is near. I can let you know.

An antenna, a receiving device, a transmitter, and an alarm device may be provided on both the truck 14 side and the person 12 side. In the case of this configuration, it is necessary to set the frequency of the radio wave emitted from the transmitter on the person 12 side and the frequency of the radio wave emitted from the transmitter on the truck 14 side differently. In such a case, both the person 12 and the truck driver are alerted by the alarm device.

When the rear tilt 18 is not conductive, a conductive material such as a plate-like material, such as iron, copper, or aluminum, a net-like material, or an interdigital shape is formed on the surface of the rear tilt-like material 18. The antenna 15 may be arranged to be larger than the antenna 15 and may be grounded. At this time, the conductive material is grounded. In this case, the same effects as those of the above embodiment can be obtained.

By connecting a coil or a capacitor to the antenna 15, the length L of the element 19 of the antenna 15, the transmission frequency of the transmitter 13, and the detection range can be adjusted.

The alarm issued by the alarm device may be not only sound but also light or vibration. That is, a warning by light includes a rotating light and a blinking light, and a warning by vibration includes a vibrator.

The antenna 15 may be arranged not only at the rear tilt 18 but also at the left or right tilt of the truck 14. In this case, a person not only behind the track 14 but also on the left or right side can be detected.

[0042]

The present invention is configured as described above, and has the following effects. According to the first aspect of the present invention, since the structural members of the automobile are used, the unidirectionality of the antenna can be easily obtained.

According to the second aspect of the present invention, since the radio wave of the transmitter is received by the antenna having a single directivity,
The radio wave can be reliably detected within a predetermined range, and an alarm can be issued.

According to the third aspect of the present invention, in addition to the effect of the second aspect of the present invention, an alarm is issued only when a specific signal is received by the authentication code. An alarm can be issued without being affected by radio waves.

According to the fourth aspect of the present invention, in addition to the same effects as those of the second or third aspect, the detection range can be adjusted according to the surrounding environment. .

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an alarm system for a vehicle according to an embodiment.

FIG. 2 is a plan view of an antenna device installed on a rear tilt of the truck.

FIG. 3 is a configuration diagram of a receiving device.

FIG. 4 is an actual vehicle evaluation result of a working distance.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 ... Warning system for vehicles, 13 ... Transmitter as an oscillation device, 14 ... Truck as a vehicle, 15 ... Antenna, 16 ... Receiving device as a receiving means, 17 ... Warning device as a warning device, 18 ... Structure of a vehicle Tilt as a member

Claims (4)

[Claims] An antenna device using an antenna and a structural member of an automobile as a ground plane of the antenna. 2. A transmitting device having a function of transmitting a signal radio wave of a specific frequency, the antenna device according to claim 1, receiving the signal radio wave of the specific frequency, and the specific frequency being connected to the antenna device. A receiving unit having a function of detecting a signal from the signal radio wave and outputting a warning signal when the voltage level of the signal is equal to or higher than a predetermined value; and an alarming unit for issuing an alarm when receiving the alarm signal. Alarm system. 3. The transmitting device has a function of including an authentication code in a signal wave transmitted by the transmitting device, and the receiving unit includes a storage device capable of storing a plurality of the authentication codes.
3. The vehicle alarm system according to claim 2, wherein the reception unit has a function of outputting an alarm signal when a code stored in the storage device matches an authentication code detected by the reception unit. . 4. The vehicle alarm system according to claim 2, wherein said receiving means has an adjusting function of outputting an alarm signal corresponding to a reception voltage level of said signal radio wave emitted by said transmission device.