JPS6091208A - Navigation device for automobile - Google Patents

Abstract

PURPOSE:To prevent unnecessary tape running at the time of restart, by detecting the separation of the cassette tape when a system is stopped. CONSTITUTION:Power of a system is supplied from a vehicle mounted battery 8. When the system is operating, a key switch 7 is closed, and the power is supplied from a main power source 114. When the system is not operating, the key switch 7 is opened, and the power is supplied to a power stop monitor 101, an RAM103, a cassette injecting monitor 104, and a VRAM106 through a back up power source 113. The cassette injecting monitor 104 records the cassette detection at the time or operation and the history of the cassette injection at the time of non-operation. Thus, the presence or absence of the history of the cassette tape injection when the system is not operated is judged, and the unnecessary running at the time of restarting can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present BA relates to a navigation device for an automobile, and particularly to an external storage device as shown in the figure.

[Background of the invention]

As shown in Fig. 1, a car navigation system displays a map on a cathode ray tube (CI(,T)2) according to the progress of a car, and the map information is magnetically stored on a cassette tape or the like. The recorded material is read out and used.Cassette tapes are inexpensive recording media.
As shown in No. 5, a music cassette tape device 5
There are quite a few that are equipped with. Therefore, the use of such a music tape device as a map data reproducing device has been considered, but there are various constraints and no examples have been put into practical use yet. One of them is the lifespan of the tape. Normally, in the case of a rectangular music tape, the tape speed is slow, and fast forwarding and rewinding are not performed frequently. Therefore, the load placed on the tape is not large. On the other hand, when using it for map data, the VM will frequently have to fast forward and rewind twice in order to search for the desired map. Furthermore, in order to search for files, it is necessary to transport the tape at high speed with the magnetic head in contact with the tape, which increases the load placed on the tape. Another problem is that it takes a long time to search for files. These problems are caused by the slow speed of the tape drive system and poor electrical frequency characteristics, unlike tape drives for computers. In order to solve the problem, it would be sufficient to improve their performance, but this would increase the cost and make the use of audio cassette decks less meaningful. If the file search time is too long, for example when driving at high speed, the map display on the CRT cannot be updated at an appropriate timing, which is a fundamental drawback for the navigation device. These problems include various factors, and improvement thereof is being studied from various aspects.

Among these, in the conventional system, there is a problem in that the tape must be run every time the system is started up, even when it is not necessarily necessary.

In other words, when using the system and restarting the vehicle after stopping temporarily in a parking lot, etc., there was previously no way to detect that the cassette tape was replaced while the system was stopped.
It was necessary to rewind the tape and read the tape's attributes recorded at the beginning of the tape, such as the chip number and recording area, before searching for the desired file.

Therefore, if the problem worsens, the CRT
It would take the same amount of time as fast-forwarding the tape from end to end until the map could be displayed.

[Purpose of the invention]

The present invention has been made in consideration of the above matters, and an object of the present invention is to provide an automobile navigation device in which an audio cassette device can be used as a map data input device. The purpose is to prevent unnecessary running of the tape when restarting the system.

[Summary of the invention]

The present invention achieves the above object by detecting removal of the cassette tape in case of system stoppage 1.

[Embodiments of the invention]

Next, one embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the components of the navigation device. The control device 1 reads map information from the cassette deck 5 and displays the map on the CRT device 2. The keyboard 6 is used to input commands from the operator and set the current position, destination, etc. The control device 1 processes and calculates the outputs of the distance sensor 3 and the direction sensor 4 according to the progress of the vehicle.
It calculates the car's current location and distance weighted with objectives and displays them overlaid on the map.

Next, a more detailed explanation will be given using FIG. The entire system is Micro Processing Unit 1 (MPU
)] Controlled by 011.

MPU 100 has read only memory (ROM) 10
It operates according to the program stored in 2. Random access memory (RAM) 103 is MPU
100 stacks or used as buffer memory. When initializing the system, the operator inputs data regarding the current position etc. from the keyboard 6, and the MPU 100 controls the cassette deck 5 based on those blue reports to load the cassette deck 5. The map data for the video is searched from the magnetic tape, and the map information is sent to the video It, AM (VB, AM) via the interface 105.
106. The map information written to VRAM (1n6) is, for example, Hitachi's HD6845S.
No Like C'RT: +n) o-5 (CRTO) 107
Then, it is converted into a signal format that can be displayed on C'FLT2, and is supplied to C'T2 via a driver and an output circuit 110. The master clock of the CRTC 107 is the oscillator 10.
Supplied from 8. A crystal resonator 109 is used as an oscillator.

The current position of the vehicle can be determined by the direction and distance traveled. The orientation sensor 4 shown in Fig. 3 is of the flux gate type 1-1', and the absolute orientation is determined by the ratio of voltages VX and VYO generated in coils wound orthogonally to each other. This is a known technique. The voltages Vx and Vy are converted into digital values in an analog/digital converter 5(AI)C) 112, and then read into the MPU 1oo via an input/output capo(Ilo) 111. Distance sensor 3H1
For example, a pickup coil detects the rotation of a permanent magnet attached to a shaft that moves with the axle. The distance is read into the MPU 100 as a pulse train.

Power for the system is supplied from the onboard battery 8, and when the system is operating, the key switch 7 is closed and the main 'i+
f, source 114 supplies 'Al:tE. When the system is not operating, the key switch 7 is in the open state, and the stop monitor 10 is connected via the backup L source 113.
1, RAMI 03, cassette eject monitor 1
04, Vl(AMI 06 are each supplied with a busy power supply. The stop monitor 101 detects and records the stoppage of the backup power supply during non-operation. As will be detailed later, the MPU 1oo is supplied with a When detected, the backup data etc. are destroyed and the system is converted to 47) M.The power outage monitor 101 can be realized, for example, by a circuit as shown in FIG. 4.Flip-flop 1011
is of the so-called D type, and is of the type that deeply retains the data at the data terminal at the rising edge of the clock. During operation, the MPU 100 sets a flip-flop via l101012. When the output of the power supply f1.113 is turned on again after dropping, the power supply waveform delayed by the resistor 1015 and capacitor 1016 is shaped by the Schmitt type gate (1010) and then passed through the flip-flop 1.
It is applied as a clock of 011.

Needless to say, the power supply of the flip-flop 1011 is sufficiently stable at this time. That is, if there is a history of power outage during non-operation, the output of flip-flop 1011 becomes 0" and is read by MPTJloo via I101012. The diode 1014 prevents current leakage during non-operation, and is a resistor. 1013 to be hoisted to the main L)X114.

Next, the cassette eject monitor 04 will be explained. This monitor is for recording the history of cassette detection during operation and cassette ejection during non-operation.
The purpose will be discussed later.

The circuit configuration is realized, for example, by a circuit as shown in FIG. Switch 115 is closed when a cassette tape is loaded. As explained in FIG. 4, when the cassette is ejected, the resistor 104 of the flip-flop 1014
The clock input, hoisted at 0, rises and the output falls. Resistance 1043.1045, diode 10
42.1046 is inserted for the same purpose as mentioned above. Also, the flip-flop 1041 is set during operation, as described above. Furthermore, if the flip tabs 1011, 1041 and the gate 1010 are of the so-called 0MO8 type, current consumption during non-operation can be suppressed.

Next, system operation will be explained using the flowchart shown in Figure @6. When the key switch 7 is turned on and the system starts, first, in 900, it is checked whether there is a history of power outages during non-operation. This is achieved by reading the output of the flip-flop tab 1011, as described above. The location of the car, the address of the cassette tape, the current map number, etc. are stored in the RAM 103 with power backup, but if there is a history of power outages, those data will be destroyed. After setting the flip tab 1011 at 901, the system is initialized at 9o2. 90
In step 3, it is checked whether there is an ejection history of the cassette tape. If it does not exist, the process jumps to step 908. On the other hand, if there is a history, flip frog 10 at 904
41, the tape is rewound (905). The first part of the tape records the tape's data, such as the map's coverage area and scale. Therefore, if there is a history of ejecting a cassette tape, there is a high possibility that the tape has been replaced.
Unless the tape is rewound, the tape data is read (906), and the target file is searched (907), lr-> is not found. Although omitted here, if the target file does not exist, it is natural that it is necessary to send a message to that effect on CI (T2) to prompt the operator to change the tape. Once the above processing is completed, Coordinate calculation (9 (18)), which is the original processing of navigation, and judgment of whether or not it is necessary to update the display map (9
09), map update (910), etc. are repeated.

In this way, it is possible to determine whether there is a history between the backup power source and the cassette eject, so for example, even if you want to re-smate after a temporary stop, you can use the current Can display a map. In this embodiment, the VRAM 106 stores and displays the map.
Since the tape is also backed up by power, there is no need to run the tape unless the current position protrudes.

This eliminates the need to rewind the tape and fast forward again to find the desired map, thereby extending the life of the tape and tape drive system.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to determine whether or not there is a history of ejecting the cassette tape during non-operation, so unnecessary tape running at the time of restarting can be prevented.

[Brief explanation of drawings]

Fig. 1 is a diagram explaining an automobile navigation device, Fig. 2 is a diagram explaining how maps are arranged on a magnetic tape, Fig. 3 is a diagram explaining the circuit configuration of the navigation device, and Fig. 4 is a diagram explaining the arrangement of maps stored on a magnetic tape. FIG. 5 is a circuit diagram for monitoring cassette tape ejection, and FIG. 6 is a flowchart showing the operation of the system. 1... Control device, 101... Power outage monitor, 104.
...Cassette eject monitor, 115...switch, 2-mine 1 Fig. 2

Claims (1)

[Claims] 1. In a navigation device having a direction detection means, a distance detection means, a control calculation means display means, and an external storage means, a power supply device that supplies power when not in operation, a device that detects and records a power outage of the power source, and the external storage. A navigation device for an automobile, characterized in that it has a device for detecting and recording whether or not a recording medium used in the device is attached.