JPH0559363U - Beacon receiver - Google Patents

Abstract

(57) [Summary] [Structure] A portable beacon receiver is composed of a base 5 and an openable / closable display unit 3, and an antenna element 1 having a predetermined directivity is provided near the tip of the display unit 3. With the display unit 3 closed, at least a portion of the base 5 facing the antenna element 1 is radio wave reflective. [Effect] When the beacon receiver is placed on the dashboard of the vehicle and the display unit 3 is opened, the antenna element 1 is located near the tip of the display unit 3, so that the base 5 and the vehicle body are greatly affected. It can receive radio waves from roadside beacons. When the display unit 3 is closed, the antenna element 1 faces the radio wave reflection plate of the base 5, so that the directivity is directed upward and the radio waves coming from diagonally forward can be received. Stable reception characteristics can be obtained without being affected by radio wave propagation conditions such as multipath fading.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a beacon receiver for displaying data to a driver by obtaining data necessary for driving assistance based on information obtained from a roadside beacon.

[0002]

[Prior Art]

 Conventionally, a roadside beacon that emits a signal containing various data from a beacon antenna in a relatively narrow range is arranged at every predetermined distance of the road traffic network, and a beacon receiver that receives the radio wave radiated from the beacon antenna has been developed. ing. The roadside beacon has a function of transmitting position data and road direction data, road congestion information around the place where the beacon antenna is installed, road information such as construction and other road usage conditions, and a beacon antenna is installed. Various types of information (hereinafter referred to as "traffic information") such as the location of facilities and houses around the location, detailed map information including personal names, and map information covering a relatively wide range including locations where beacon antennas are installed. ) Is sent.

On the other hand, in order to assist the vehicle traveling on an unfamiliar land, it is composed of a position detection unit that detects the current position of the vehicle based on the outputs from the distance sensor and the direction sensor, a CD-ROM, and the like. An in-vehicle navigation device having a map memory, a display device, and a control unit for reading a road map including the current position of the vehicle detected by the position detection unit from the map memory and displaying the road map on the display device has been put into practical use.

In such a navigation device, the current position of the vehicle on the display device largely deviates from the actual position due to an increase in the traveling distance due to the errors that the vehicle speed sensor and the direction sensor necessarily have. There is a risk that In addition, when running near a railroad track, a large error may occur in the direction sensor due to the magnetic effect.

Therefore, the beacon receiver is mounted on the vehicle in order to capture the position data and the road direction data radiated from the roadside beacon into the navigation device and calibrate the current position and direction of the vehicle to be correct. .. Therefore, since the beacon receiver has a function of calibrating the navigation device, the beacon receiver is often mounted on the vehicle in a form attached to the navigation device. In this case, the receiving antenna was fixed to the roof of the vehicle to reduce the sensitivity to reflected and scattered waves from the road surface coming from below the horizontal direction, and was connected to the receiver with a coaxial cable (special feature). (See Japanese Laid-Open Patent Publication No. 62-212898).

However, since the beacon receiver can capture not only the position data and the road direction data but also the traffic information data as described above, not only the vehicle equipped with the navigation device but also the navigation device can be used. It is also useful for vehicles that are not equipped at all. For this reason, there is a demand for a beacon receiver that can be easily brought into a vehicle without being presumed to be connected to a navigation device.

FIG. 12 is a perspective view showing such a simple beacon receiver, in which a thin display element 4 is incorporated in a lid portion of a foldable housing. When using this beacon receiver, place it on the dashboard inside the vehicle and use it with the lid raised, as shown in Fig. 13, but it blocks the view, so it is not used when you want to see the display. It is envisioned that the lid will be closed. It is desirable to be able to receive radio waves even in this state. This is because even when the lid is closed, it is necessary to receive the information from the roadside beacon and store it in the memory in order to process the information later.

[0008]

[Problems to be solved by the device]

 By the way, beacon antennas are mostly installed on the side of the road using existing structures such as lighting columns and sign columns as shown in Fig. 14, and it is ideal for looking down the road from a high place. Therefore, the directivity of the beacon antenna has an appropriate depression angle.

Therefore, the receiving antenna of the beacon receiver needs to be set such that the directivity is horizontal or slightly upward. By doing so, the sensitivity to reflected and scattered waves from surrounding buildings and other vehicles coming from below the horizontal direction can be reduced, and the effects of multipath fading can be reduced. However, when the portable beacon receiver as described above is used, there is a problem that the reception condition differs depending on whether the lid is open or closed, and the reception condition deteriorates in either case.

Therefore, an object of the present invention is to solve the above-mentioned problems and to stably receive the radio wave from the beacon antenna regardless of the usage state in a simple beacon receiver that can be brought into a vehicle. To provide a beacon receiver that can.

[0011]

[Means for Solving the Problems]

 The beacon receiver according to claim 1 for achieving the above object, the beacon receiver comprises a base and an openable / closable display unit, and an antenna element having a predetermined directivity near the tip of the display unit. Is provided, and at least the portion of the base that faces the antenna element is radio wave reflective with the display unit closed.

Further, in the beacon receiver according to claim 2, a first antenna element having a predetermined directivity is provided near the tip of the display unit, and the beacon is placed outside the display unit in a state where the display unit is closed. The second antenna element having directivity toward the direction is provided in the display unit, and if it is confirmed by the opening / closing detection means that detects the open / closed state of the display unit that the display unit is open, reception from the first antenna element A switching means is provided for taking in radio waves from the second antenna element to the receiving section when the radio waves are taken into the receiving section and the display section is confirmed to be closed.

[0013]

[Action]

 According to the configuration of the invention of claim 1, since the antenna element is located near the tip of the display unit when the display unit is open, the antenna element is not greatly affected by the base and the vehicle body. , It can receive radio waves from roadside beacons.

When the display unit is closed, the antenna element faces the radio wave reflection plate of the base, so that the directivity is directed upward and the radio waves coming from diagonally above can be received. Therefore, in either case, stable reception characteristics can be obtained without being affected by radio wave propagation conditions such as multipath fading.

According to the configuration of the invention of claim 2, when the display unit is opened, the first antenna element having a predetermined directivity is located near the tip of the display unit. It is possible to receive radio waves from roadside beacons without being greatly affected by the base or vehicle body. When the display unit is closed, radio waves are received by the second antenna element having directivity directed outward from the display unit, so the directivity is directed upward, and radio waves coming from diagonally above can also be received. ..

Therefore, in either case, stable reception characteristics can be obtained without being affected by radio wave propagation conditions such as multipath fading.

[0017]

【Example】

 Embodiments will be described in detail below with reference to the accompanying drawings. FIG. 1 is a side sectional view of a beacon receiver according to the first embodiment. The beacon receiver has a base 5 and a display unit 3 that can be opened and closed. (A) shows a state in which the display unit 3 is open, and (b) shows a state in which the display unit 3 is closed.

The display section 3 is made of a radio wave transmitting material such as resin, and the antenna element 1, the receiving circuit 2 and the display element 4 are incorporated therein. The base 5 is made of metal so as to serve as a reflector of the antenna element 1 with the display unit 3 closed. A metal plate 9 may be attached to the portion of the base 5 facing the antenna element 1 with the display unit 3 closed (see FIG. 2). Instead of attaching the metal plate, a metal film is formed by vapor deposition. You may.

As shown in FIG. 3, the antenna element 1 has an inverted L shape, and is arranged in the receiving circuit 2 so that the side 11 at the tip of the antenna element 1 is parallel to the upper side of the display unit 3. It is fixed. The coordinate system fixed to the display unit 3 is shown in FIG. The receiving circuit 2 is built in the display unit 3 so as to be directly connected to the antenna element 1. A control unit 7 is built in the base 5.

The beacon receiver is placed on the dashboard in the vehicle as shown in FIG. 13, and is used with the display unit 3 opened and the display unit 3 closed. When the display unit 3 is open, the directivity of the antenna element 1 is almost the same as the directivity of the antenna element alone (see Fig. 4), and the beacon antenna that passes through the front glass of the automobile and arrives from the upper front. You can receive radio waves from.

On the other hand, in the state where the display unit 3 is closed, the directivity of the whole is a single leaf oriented in the direction (−x direction) perpendicular to the back surface of the display unit 3 because of the metal reflection directly below the antenna element 1. It becomes directional (see FIG. 5). Therefore, the directivity is almost upward, but since it has sensitivity in the diagonally upward direction as well, it is possible to receive the radio wave from the beacon antenna that arrives from the front through the windshield of the automobile, and the multipath fading Good reception characteristics not affected by

FIG. 6 is a side sectional view of the beacon receiver according to the second embodiment. In this embodiment, the display unit 3 is provided with the first antenna element 1a and the second antenna element 1b, and the open / closed state of the display unit 3 is detected in the vicinity of the open / close shaft of the display unit 3. An open / close detection sensor 8 is provided. FIG. 7 is a block diagram of an electric circuit. The outputs of the first antenna element 1a and the second antenna element 1b are supplied to the changeover switch 81, and the output of the changeover switch 81 is supplied to the receiving circuit 2. The changeover switch 81 may be an electronic switch using a diode or a mechanical relay. The beacon signal demodulated and waveform-shaped by the receiving circuit 2 is stored in the control unit 7, signal-processed, converted into an image signal and then sent to the display element 4, where it is displayed on the screen.

The changeover switch 81 operates according to the open / close detection signal of the open / close detection sensor 8 (which can be manufactured by a micro switch), and when the display unit 3 is open, the first antenna element 1 a To the side of the second antenna element 1b when the display unit 3 is closed. In this embodiment, a monopole antenna is used as the first antenna element 1a, and a microstrip antenna is used as the second antenna element 1b. The monopole antenna has the structure shown in FIG. 8, in which a strip line 22 is formed on one surface of an insulating print substrate 21 and a copper foil 23 is formed on the entire back surface. The microstrip antenna has the structure shown in FIG. 9, and a strip copper plate 32 is attached to one surface of an insulating printed circuit board 31, and a copper plate 33 is attached to one surface on the back side. The high frequency signal is fed from the feeding point 34 through the connector 35 on the back side.

In the state where the display unit 3 is opened, the directivity of the first antenna element 1a is almost the same as the directivity of the antenna element alone (see FIG. 10). Radio waves can be received from the beacon antenna. On the other hand, when the display unit 3 is closed, the directivity of the second antenna element 1b becomes a single-leaf directivity directed in the direction (−x direction) perpendicular to the back surface of the display unit 3 (see FIG. 11). Therefore, similar to the first embodiment, good reception characteristics that are not affected by multipath fading can be obtained.

The present invention is not limited to the above embodiment. For example, as the antenna element 1, a dipole antenna, a notch antenna, or the like may be used in addition to the inverted L-shaped antenna. For the first antenna element 1a, a combination of a plurality of monopole antennas, an inverted L-shaped antenna, a notch antenna, etc. may be used in addition to a single monopole antenna. For the second antenna element 1b, a slot antenna, a dipole antenna with a reflector, or the like may be used instead of the microstrip antenna.

Other various modifications can be made without changing the gist of the present invention.

[0027]

[Effect of the device]

 As described above, according to the beacon receiver of the present invention, it is possible to efficiently receive the radio wave coming from the beacon antenna whether the display unit is open or closed. .. Therefore, a beacon receiver that can be easily carried into the vehicle and is easy to use can be realized.

[Brief description of drawings]

FIG. 1 is a side sectional view of a beacon receiver according to a first embodiment, (a) showing a state in which a display unit 3 is opened, and (b) showing a state in which the display unit 3 is closed.

FIG. 2 shows the antenna element 1 with the display unit 3 closed.
It is a figure which shows the modification which attached the metal plate 9 to the part of the base 5 which opposes.

FIG. 3 is an antenna element 1 having an inverted L shape.
FIG.

FIG. 4 is a graph showing the directivity of the antenna element 1 when the display unit 3 is opened.

FIG. 5 is a graph showing the directivity of the antenna element 1 when the display unit 3 is closed.

6A and 6B are side cross-sectional views of the beacon receiver according to the second embodiment, where FIG. 6A shows a state in which the display unit 3 is opened, and FIG. 6B shows a state in which the display unit 3 is closed.

FIG. 7 is an electric circuit block diagram of a beacon receiver.

FIG. 8 is a perspective view showing a structure of a monopole antenna as a first antenna element.

9A is a perspective view showing the structure of a microstrip antenna as a first antenna element, and FIG. 9B is a side sectional view.

FIG. 10 is a graph showing the directivity of the first antenna element 1a when the display unit 3 is opened.

FIG. 11 is a graph showing the directivity of the second antenna element 1b when the display unit 3 is closed.

FIG. 12 is a perspective view showing the outer shape of a beacon receiver.

FIG. 13 is a diagram showing a state in which a beacon receiver is installed inside a vehicle.

FIG. 14 is a diagram showing an installation state of roadside beacons.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Antenna element 1a 1st antenna element 1b 2nd antenna element 2 Reception circuit 3 Display part 4 Display element 5 Base stand 7 Control part 8 Open-close detection sensor 9 Reflector plate

Claims (2)

[Scope of utility model registration request] 1. Based on information obtained from a roadside beacon,
In a beacon receiver that obtains data necessary for driving assistance and displays it to the driver, the beacon receiver is composed of a base and an openable / closable display unit, and has a predetermined directivity near the tip of the display unit. A beacon receiver, characterized in that an antenna element is provided, and at least a portion of the base facing the antenna element is radio wave reflective in a state where the display section is closed. 2. Based on information obtained from roadside beacons,
In a beacon receiver that obtains data necessary for driving assistance and displays it to the driver, the beacon receiver is composed of a base and an openable / closable display unit, and has a predetermined directivity near the tip of the display unit. A first antenna element is provided, and a second antenna element having directivity outward from the display unit is provided in the display unit with the display unit closed, and an open / close detection for detecting the open / closed state of the display unit is provided. If it can be confirmed by the means that the display section is open, the reception radio wave from the first antenna element is introduced into the reception section, and if it is confirmed that the display section is closed, the reception radio wave from the second antenna element is received. Beacon receiver characterized by being provided with a switching means for incorporating the signal into the receiving section.