JP2894872B2 - Navigation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a navigation device.

[0002]

2. Description of the Related Art Global positioning system GPS (Globa)
l Positioning System is a global navigation system using satellites developed by the US Department of State. At present, automobiles, ships, aircraft, etc. are receiving signals from satellites. This system is composed of 24 satellites including a spare unit. By using three satellites, two-dimensional positioning can be performed.
In addition, three-dimensional positioning is performed using four pieces. But GP
Since S uses SHF radio waves, it is often attenuated or blocked by tunnels, valleys of buildings, rainfall, cumulonimbus clouds, etc., and cannot be received. In addition, there are times when there are no satellites at this time, so accuracy is good. However, there are various problems in using it for cars. In addition, the life of satellite solar cells is short,
There is also a problem that transmission becomes impossible due to weak radio waves. In addition, in a navigation system using self-contained navigation using a geomagnetic sensor and a distance sensor using a tire, it was necessary to modify the car because data had to be taken from the tire. In addition, since this distance sensor is fixed to a car, this system cannot be used in a car without a distance sensor. On the other hand, the self-contained navigation using an acceleration sensor has a lower accuracy than a distance sensor using a tire and is not generally used at present.

[0003]

SUMMARY OF THE INVENTION As mentioned earlier, GP
Since the navigation system using S uses SHF radio waves, it cannot be received in tunnels or valleys of buildings.
During this time, when the track of the car cannot be displayed on the display unit and the GPS receiver receives a signal again, the map on the display unit is switched and the usability is poor. SUMMARY OF THE INVENTION It is an object of the present invention to provide a navigation device capable of obtaining a continuous track even when a GPS receiver cannot receive a signal. In addition, portable and accurate navigation
It is to get an action system.

[0004]

A GP for outputting an absolute position
An S receiver, a geomagnetic sensor for obtaining a bearing, an acceleration sensor for obtaining a distance, a map storage unit for storing and storing map information, a display unit for displaying map information read from the map storage unit, A control unit for selecting information using a GPS receiver or a geomagnetic sensor and an acceleration sensor in accordance with the arrival condition of radio waves, and a control unit for controlling a display unit, a map storage unit, and the like; When there is no information, the information from the acceleration sensor and the geomagnetic sensor is used.

[0005]

According to the present invention, two systems, namely, G
A system using a PS and a system using a geomagnetic sensor and an acceleration sensor are combined, and when the GPS cannot be received, a continuous track is displayed on the display unit by supplementing the track of the vehicle with another system.

[0006]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is an external perspective view of a navigation device. In FIG. 1, reference numeral 1 denotes an antenna for receiving GPS radio waves from satellites. To perform positioning by GPS, radio waves from four satellites must be received at the same time. It is not possible to use an antenna having a large gain and a planar antenna such as an orthogonal dipole antenna, a helical antenna, or a microstrip antenna is generally used.
Reference numeral 2 denotes a GPS receiver. GPS radio waves obtained from an antenna are processed inside the receiver and output the absolute position of longitude and latitude.
Reference numeral 3 denotes a control unit which, when a reception signal from the GPS receiver 2 is interrupted, switches to a system including an acceleration sensor 4 and a geomagnetic sensor 5 to be described later and inputs the signal to the display unit 6 or reads from the map storage unit 7. And controls such as storage. The terrestrial magnetism sensor 5 has a toroidal ferrite core provided with a set of detection coils orthogonal to the excitation coil, and the direction of the azimuth is displayed by extracting a change in magnetic flux by the excitation coil due to an external magnetic field.

[0007] The acceleration sensor 4 extracts acceleration by a piezoelectric element. When acceleration is felt, the piezoelectric element is deformed. A voltage is generated by a piezo phenomenon according to the deformation. The speed of the acceleration sensor 4 is obtained by integrating the output of the piezoelectric element with time. This speed is further integrated to indicate the distance. By combining this output with the output of the geomagnetic sensor 5, the relative position of the vehicle can be determined. However, accuracy is degraded due to double integration for obtaining the distance. However, a short distance is sufficient for GPS correction. In addition, since there is no need to take a signal from a car part such as a tire, it is advantageous that the car does not need to be modified. Reference numeral 6 denotes a display unit which reads out a necessary map 12 based on a signal from the control unit 3 and displays a current position thereon. Liquid crystal panel (LC
Use D). When the size is not limited, a CRT or the like may be used. 7 is a map storage unit which is a CD-R as a medium.
OM is used, and CD-ROM
A map 12 of a necessary place is output from the map data read from the display unit 6 to the display unit 6. In addition, an IC memory, an optical card, or the like can be used as the medium. 8 is a handle. In this embodiment, the antenna 1 and the display unit 6 are detachable, so that they can be carried by attaching an external battery 9, and as shown in FIG. If it is rotatable, the case 13
When viewing the display unit, the display unit can be appropriately tilted. The display section can be separated from the case 13 and connected to each other by a lead line.

Reference numeral 10 denotes a power supply terminal. If the antenna 1 is moved, the navigation device can be moved from the car A to the car B without modifying the car. Power supply terminal 10
It only needs to be connected to a writer and can be used like a CD radio cassette. Reference numeral 11 denotes a support for the LCD display unit.

Next, the map shown on the display unit of the present invention, FIG.
Will be described. Reference numeral 12 denotes a map displayed on the display unit 6. Now, when going from point A to point E in FIG. 3, turn right at point B and pass point C, point H, point I and point D to point E. If there is a GPS signal, the map is switched at point I and the position is displayed continuously. Next, GP at point C
If the S radio wave is cut off and the signal can be received again at the point D, the map is suddenly switched, and the user is very confused. Therefore, when the radio wave becomes unreceivable at the point C as in the present embodiment, a signal indicating that the radio wave cannot be received appears in the control unit 3 and switches to a signal from a geomagnetic sensor or an acceleration sensor provided with the signal. In this case, since the integration of the distance is small at the point I, the map is almost correctly switched at the point I and reaches the point D. At the point D, the GPS signal is switched again. However, since the error is small and the movement of the map is small, the user is not confused.

[0010]

As described above, according to the present invention, when a GPS receiver becomes unreceivable, a system using an acceleration sensor and a terrestrial magnetism sensor instead of a GPS is used to supplement the trajectory of the map on the display unit. Can be uninterrupted.
Therefore, if GPS cannot be received for a certain period of time and reception becomes possible after a while, even if the map is switched, there is no uncomfortable feeling. Also, since the present invention has a built-in case other than the antenna, it can be carried anywhere by attaching an external battery, not only to the sea and mountains, but also to the antenna without modifying the automobile. -The navigation system can be used immediately by simply attaching the power supply to the cigarette lighter and taking power from the cigar lighter. In addition, since the display unit is rotatable, the display unit can be tilted at an easy-to-view angle, and can be stored in a case when being carried, so that it is easy to carry. Further, since the display unit is detachable, the display unit can be set at a place where the display unit can be easily seen.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is an external perspective view of a navigation device according to one embodiment of the present invention.

FIG. 3 is a map shown on a display unit of the navigation device according to the embodiment of the present invention;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Antenna 2 GPS receiver 3 Control part 4 Acceleration sensor 5 Geomagnetic sensor 6 Display part 7 Map storage part 10 Power supply terminal 12 Map 13 Case

Continuation of the front page (56) References JP-A-2-216011 (JP, A) JP-A-3-48716 (JP, A) JP-A-64-80815 (JP, A) JP-A-62-98214 (JP) , A) Fully open 1988-62715 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01C 21/00 G01S 5/14 G09B 29/00

Claims (3)

(57) [Claims] 1. A GPS receiver indicating an absolute position, a geomagnetic sensor for obtaining an azimuth, an acceleration sensor for obtaining a distance, a map storage unit for storing and storing map information, and reading from a map storage unit. A display unit for displaying map information;
A control unit that selects a signal of the PS receiver and a signal of the geomagnetic sensor and the acceleration sensor, and controls a display unit, a map storage unit, and the like. When there is no signal from the GPS, information from the acceleration sensor and the geomagnetic sensor is provided. Navigation device characterized by switching to 2. The navigation device according to claim 1, wherein the display unit is rotatably housed in a case. 3. The navigation device according to claim 1, wherein the display unit is detachable.