Boots – shoes – and leggings
Patent
1984-12-18
1987-05-12
Chin, Gary
Boots, shoes, and leggings
235 95R, G01C 2200
Patent
active
046654976
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an electronic odometer, and particularly to an electronic odometer that is suitable for use in a vehicle such as an automobile.
BACKGROUND ART
Recently, proposals for an instrument indicating the total distance traveled by an automobile concern an electronic odometer employing non-volatile memories as a substitute for a mechanical instrument which indicates the total distance traveled by a vehicle.
An electronic odometer is powered by the battery of the automobile, and digitally displays the total distance traveled, which is integrated by a counter. According to this device, data on distance traveled is written into a plurality of non-volatile memories every 100 meters, and then that value is read out and indicated, in order to prevent loss of the data on distance traveled as integrated by the counter if the voltage should drop such as when the battery is changed or a wire breaks. At the moment, however, there is a limit on the number of times data can be written into non-volatile memories. With this method, therefore, the odometer can be used for only about ten thousand kilometers, although the automobile can, in practice, travel a total distance of more than a hundred thousand kilometers. One method of solving this problem is disclosed in Japanese Patent Laid-Open No. 95813/1980 laid open in Japan on July 21, 1980, and entitled "Odometer", and involves a method of reducing the number of times data is written into the non-volatile memories. Japanese Patent Laid-Open No. 93209/1977 laid open in Japan on June 10, 1982 and entitled "Odometer for Automobile" discloses a method in which the distance traveled is determined based upon a majority rule, by writing the distance traveled into a plurality of non-volatile memories and then reading the written data out of the non-volatile memories. In either case, data is written repeatedly into the same locations of non-volatile memories, data transfer is destroyed during the writing period (about 300 ms), so that incorrect data could be input to the non-volatile memories unless a large capacitor is provided to back up the power source or unless a large-capacity storage battery is provided.
DICSLOSURE OF INVENTION
An object of the present invention is to provide an electronic odometer which is capable of extending the life of non-volatile memories, and which is capable of correctly indicating the total distance traveled by the automobile.
Another object of the present invention is to provide an electronic odometer which is capable of utilizing non-volatile memories to the maximum, and which is also capable of extending the life thereof.
A further object of the present invention is to provide an electronic odometer which is capable of indicating the distance traveled by the automobile up to the moment that the engine is turned off.
The characteristic feature of the present invention resides in that the distance traveled by the automobile is written, after each predetermined distance traveled, into a location of a non-volatile memory which has N locations, N.sub.1 to N.sub.N, so that data on the total distance traveled is stored. This makes it possible to extend the life of the non-volatile memory, and correctly indicate the total distance traveled by the automobile, as described later.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a basic block diagram of the present invention;
FIG. 2 is a diagram of a specific embodiment of FIG. 1;
FIG. 3 is a timing chart illustrating the writing operation of the embodiment of FIG. 2;
FIG. 4 is a timing chart illustrating the reading operation of the embodiment of FIG. 2;
FIG. 5 is a flow chart of an embodiment of a main processing program in the arithmetic unit of FIG. 2;
FIG. 6 is a flow chart of an embodiment of an interrupt processing program in the arithmetic unit of FIG. 2;
FIG. 7 is a flow chart of an embodiment of the write processing of FIG. 5;
FIG. 8 is a flow chart of an embodiment of the read processing of FIG. 5;
FIG. 9 is a diagram showing how the non-volatile memory
REFERENCES:
patent: 4031363 (1977-06-01), Freeman et al.
patent: 4409663 (1983-10-01), Becker et al.
patent: 4539641 (1985-09-01), Kawashimo et al.
patent: 4559637 (1985-12-01), Webber
Katogi Kozo
Naito Shotaro
Yamamura Hirohisa
Chin Gary
Hitachi , Ltd.
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