JP2529111Y2 - Satellite signal receiving antenna device for vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to a structure of a vehicular satellite signal receiving antenna device used for a traveling guidance device of an automobile or the like.

(Prior Art) Now, for example, suppose that a driver is driving to a certain destination while driving a car. In a lonely space isolated from the outside of a car, a driver maps a strange land with a map. It can be said that he is simply stepping on the accelerator to his intended destination, relying on road signs and landscape.

In other words, even today, when computers and data communication have been developed and information is said to be excessive, the essence of driving a car is almost the same as when the car was invented.

In view of such circumstances, recently, a vehicle travel guidance device generally called a navigation system has been increasingly developed.

The navigation system detects, for example, a horizontal component of a geomagnetic vector and uses it as a direction parameter (hereinafter referred to as a geomagnetic method) or a gas rate gyro using inertia of helium gas as a direction sensor. In addition to the GPSS system (hereinafter referred to as the inertial navigation system), the GPSS system (at least three circular orbiting satellites (called navigation satellites) that can detect the exact position anywhere on the earth A system such as Global Positioning System with Satellite) has been proposed.

By the way, in such a traveling guidance device for a vehicle, it is most important that the guidance accuracy is high first, in addition to the cost problem. It is the vehicle position detection performance of the vehicle position recognition means that basically determines the guidance accuracy. Therefore, from this viewpoint, the GPSS system using an artificial satellite among the above-mentioned three traveling guidance systems (own vehicle position detection system) is the most promising at present.

In the case of the GPSS system, the distance information and the time information from a plurality of (at least three) satellites are received, and the absolute position of the vehicle in two or three dimensions can be recognized. There is an advantage that a sufficiently high own-vehicle position detection capability (positioning error of about ± 30 m) can be ensured without the need for correction by means. Further, even when the vehicle is transported by sea on a ferry boat or the like, it is not necessary to set the own vehicle position again, which is convenient.

(Problems to be Solved by the Invention) Incidentally, a circular flat plate antenna is generally used as a receiving antenna of the vehicle-side GPS receiver (satellite signal receiver) in the GPSS method. As shown in FIG. 7, it is installed on the upper surface of the roof portion 81 of the vehicle A and configured to receive a transmission signal from a GPS satellite at a wide angle (360 °).

However, for example, as shown in the graph of FIG.
Each of the S-navigation satellites has a time when positioning is possible and a time when positioning is not possible within a day,
It is defined in relation to the elevation angle θ with respect to the GPS navigation satellite.

Therefore, basically, assuming that a specific GPS navigation satellite is in a time zone in which positioning is possible for the time being, the smaller the incident elevation angle θ (closer to the horizontal) with respect to the transmission signal on the receiving antenna side, the better, and the longer time, Positioning becomes possible.

However, as can be understood from the graph of FIG. 8, when the angle of incidence θ becomes smaller than a certain value (θ = 6 °), for example, attenuation due to the influence of the density of the atmospheric layer or the presence of mountains, buildings, and the like. Electric field level stabilized by shielding radio waves,
In some cases, it becomes impossible to receive a transmission signal with an appropriate arrival time.

As a result, there is a problem in that when the position of the own vehicle is measured by the signal in the area, incorrect recognition of the own vehicle position is caused.

(Means for Solving the Problems) The invention of the present application has been made for the purpose of solving the above problems, and is provided on a vehicle body upper surface portion.
A vehicular satellite signal receiving antenna device that receives transmission signals of a predetermined frequency band from a plurality of artificial satellites and detects the position of the vehicle based on the reception timing of each of the signals. , An elevation control member provided around the antenna element and configured to restrict an incident elevation angle of a transmission signal from each of the satellites incident on the antenna element.
The antenna device is characterized in that the antenna element is set to an incident elevation angle restriction angle which does not have a stable electric field level and an appropriate arrival time with respect to the antenna element and does not receive a transmission signal having a predetermined incident elevation angle or less.

(Operation) In the configuration of the vehicular satellite signal receiving antenna device of the present invention, the antenna is arranged around a flat antenna element capable of receiving transmission signals from a plurality of satellites at an incident azimuth as wide as possible. When the antenna element receives a transmission signal within the range of the incident elevation angle at which the antenna element obtains a stable electric field level and an appropriate arrival time, the incident angle of the transmission signal from a plurality of satellites with respect to the element is increased. There is provided an incident elevation restriction member configured to be set to an incident elevation restriction angle for restricting a transmission signal having a possibility of erroneous positioning to an unreceivable incident elevation angle.

For this reason, for example, the transmission signal from an unstable and random satellite having an incident elevation angle θ of about 6 ° or less, which leads to erroneous positioning as described above, can be reliably cut, and the vehicle in the accurate positioning area alone can be cut off. The position can be measured and recognized.

(Effects of the Invention) Therefore, according to the vehicular satellite signal receiving antenna device of the present invention, it is possible to realize an accurate vehicular reception system without erroneous positioning due to the influence of the atmospheric layer density near the ground surface or the influence of radio wave obstacles. .

(Embodiment) FIGS. 1 to 6 show a configuration and an operation of a traveling guidance device for a vehicle including a satellite signal receiving antenna device according to an embodiment of the present invention. First, FIG. 3 shows a system structure of a traveling guidance device for a vehicle in the embodiment. Reference numeral 10 denotes a navigation control unit which is a center of a control unit. Equipment (hereinafter simply referred to as CPU) 1
1, a read-only memory (hereinafter referred to as ROM) 12 with a built-in control program, a random access memory (hereinafter simply referred to as RAM) 13 for storing various control data at any time, and between the CPU 11 and various external devices described later. It is composed of an interface circuit 14 for inputting and outputting data.

And the above navigation control unit 10
An external device to be combined with the map information and altitude data of a CD-ROM (compact disk type read-only memory) 1 in which a large number of map-type travel guidance information including altitude data are stored at a plurality of scales. , An operation switch section 3 for performing various operations such as setting and changing and resetting of a destination, changing an optimum route, and displaying details of a map, and detecting a current position Pn of the vehicle. A vehicle position recognition device 4, a display control circuit 5 for inputting an image signal output from the CPU 11 and displaying the image signal output on a screen of a CRT display 6 in a meter cluster unit, a video memory 7 attached to the display control circuit 5, and the like; Is provided.

The CD player 2 drives the CD-ROM 1 and drives the CD-RO
Outputs the map information of the required predetermined area and the corresponding altitude data among the map information of all over Japan stored in M1 according to the designated address (designated by east, west, north and south), and outputs the decoder 8 and the interface. Above via circuit 14
Input to CPU11. These pieces of read information are temporarily stored in the RAM 13. The output of the CD player 2 decoded through the decoder 8 is also output to the side of a normal in-vehicle audio device (AMP, equalizer, speaker, etc.) 9.

The mounting CD-ROM 1 stores about 30,000 pieces of map information of color still images together with, for example, altitude data. For example, in the case of this embodiment, at least two types of scales (normal / enlarged) ) Are prepared, and four levels (area level a: 1 to
It is configured to be able to enlarge or reduce 4).

Next, the operation switch 3 is formed of, for example, a screen touch type, and includes (1) menu, (2) information, and (3)
Reset, (4) enlarge, (5) shrink, (6) detail, (7)
Various operation switches, such as correction and (8) altitude reading, are provided. The ON output of the operation switch 3 is coded by the encoder 16 and then input to the CPU 11 via the interface circuit 14. The CRT 11 performs a predetermined calculation (program processing) in response to the input of the operation switch 3 to operate the display control circuit 5 for driving the CRT to display an image corresponding to the contents of the command.

Further, in the case of the present embodiment, the own vehicle position recognizing device 4 for recognizing the current own vehicle position is, for example, as shown in FIG.
It is configured by combining two sets of own-vehicle position recognizing means with the second own-vehicle position recognizing means 4B based on the SS system, and inputs respective outputs thereof to the CPU 11 via the switching circuit 20. .

First, as shown in FIG. 4, the first vehicle position recognizing means 4A receives a vehicle speed sensor 42 for detecting a vehicle speed, a geomagnetic sensor 41 composed of a magnetic compass, and respective detection signals of the two sensors 42, 41. The signal processing circuit 43 detects the current position of the vehicle by detecting the traveling direction of the vehicle and the relative distance from the reference value. Also, the second vehicle position recognition means 4B
As described above, for example, a global positioning satellite system (GPSS) shown in FIG. 5 is used, and as shown in FIG.
And at least four artificial navigation satellites (GPS navigation satellites) 77A to 77D each receiving a radio wave from the ground station antenna 75
And a monitor station 85 that receives radio waves from each of these navigation satellites 77A to 77D, calculates a deterioration coefficient indicating the degree of a positioning error of the radio waves, and superimposes the deterioration coefficient on the radio wave from the ground antenna 75. As shown in FIG. 4, a GPS receiver 44 for receiving the transmission radio waves from the four GPS navigation satellites 77A to 77D and a reception timing between the radio waves received by the GPS receiver are shown in FIG. And a signal processing circuit 45 for detecting the distance, altitude, and time between the four satellites 77A to 77D and the vehicle A based on the signal, and absolutely detecting the current position of the vehicle A. Coefficient judgment circuit to judge
46 and. The deterioration coefficient judging circuit 46 uses the GPS
When the degradation coefficient value, including a radio wave across the receiver 44 has received is a predetermined value or more, and the signal strength (field intensity: D _B) is time of less than a predetermined value (for example, the vehicle is traveling secondary in a tunnel When a radio wave cannot be received, the positioning error increase signal is output. Further, the vehicle position recognizing means 4 shown in FIG.
Is the means of recognizing the position of each vehicle of the geomagnetic type and the satellite type.
A switching circuit 20 for selectively switching between A and 4B. The switching circuit 20 is a satellite-based second vehicle position recognizing means when the positioning error increase signal from the deterioration coefficient determination circuit 46 is not output.
4B, on the other hand, when the positioning error increase signal is output, the first self-vehicle position recognizing means 4A of the terrestrial magnetism type is selected, and the current own-vehicle position signal of the selected vehicle is transmitted to the navigation control unit 10. Output to CPU11.

However, the GPS receiver 44 has, for example, FIGS.
An antenna 80 for receiving satellite signal radio waves as shown in the figure is provided. The antenna 80 has a quarter-wavelength circular flat plate-shaped antenna element 80a installed and fixed on the upper surface of the vehicle body roof portion 81 of the vehicle similarly to the conventional antenna shown in FIG. And a radio wave incident elevation angle restricting member 80b having a cylindrical incident elevation angle restricting wall provided at the second position. The radio wave incidence elevation angle control member 80b is formed to have a shield structure capable of shielding radio waves, and the height H of the regulating wall in the vertical direction is set to a stable electric field level and a proper arrival time. In order for a signal to be incident, for example, the incident angle θ of the transmission radio waves from the navigation satellites 77A to 77D is set to be, for example, θ = about 10 ° or more.

Therefore, according to the antenna structure, for example, a satellite radio wave in an unstable and random positioning area of θ = about 6 ° or less as shown in the graph of FIG. 8 is not received,
The possibility of erroneous positioning of the vehicle position _{Pn as in} the related art is eliminated.

Then, the navigation control unit 10 shown in FIG. 3 always sets the optimal route in relation to the destination Po set in advance based on the actual vehicle position Pn recognized as described above. Navigation control is performed so as to follow, and the display of the optimum route in relation to the destination Po is made, for example, as shown in FIG.

That is, first, before starting operation,
In S1, the above-mentioned CD-ROM ₁ is loaded into the CD player 2, and the CD player 2 is driven. As a result, the map information (normal scale) of the optimal traveling circuit set corresponding to the destination Po to be made from now on can be read.

Next, in step S _2, specifically set a destination Po to go from now by operating the operation switch 3.

Further, in this state, the above-mentioned own-vehicle position recognizing means 4 is _operated to read an accurate own-vehicle position P _start (input to the RAM).

Then, the following step S ₃ in the current vehicle position P _start
From the start point P _start based on the optimal route (No. 1 map) is displayed on the screen of the CRT display 6 on the meter cluster side. The vehicle position mark MP is plotted on the map road on the screen in a superimposed state. Then, this is sequentially updated as the vehicle advances.

Then, the navigation traveling is continued in this manner.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a satellite signal receiving antenna device used for a vehicle guidance device according to an embodiment of the present invention.
FIG. 3 is a perspective view of the same, FIG. 3 is a block diagram showing an overall system configuration of the traveling guidance device, FIG. 4 is a block diagram showing an internal configuration of the own vehicle position recognition device of FIG. FIG. 5 is an explanatory diagram showing the recognition principle of the own vehicle position recognition device, and FIG.
FIG. 7 is a flowchart showing the basic control operation of the navigation control unit in the configuration of FIG. 3, FIG. 7 is a perspective view showing the configuration of a conventional satellite signal receiving antenna, and FIG. It is a prediction of the arrival of a satellite. 1 ... CD-ROM 2 ... CD player 3 ... operation switch 4 ... own vehicle position recognition device 6 ... CRT display 10 ... navigation control unit 11 ... CPU 41 ... geomagnetic sensor 42 ... wheel speed sensor 44 GPS receiver 77A-77D Navigation satellite 80 Flat antenna 80a Antenna element 80b Incident elevation angle limiting member

Claims (1)

(57) [Scope of request for utility model registration] 1. A vehicular satellite that is installed on the upper surface of a vehicle body, receives transmission signals in a predetermined frequency band from a plurality of artificial satellites, and detects the position of the vehicle based on the reception timing of each of the signals. A signal receiving antenna device, comprising: a flat antenna element; and an incident elevation angle regulating member provided around the antenna element and regulating an incident elevation angle of a transmission signal from each of the satellites incident on the antenna element. The incident elevation angle restricting member is set at an incident elevation angle restricting angle that does not have a stable electric field level and an appropriate arrival time with respect to the antenna element and that does not receive a transmission signal having a predetermined incident elevation angle or less. Vehicle signal receiving antenna device.