JPH0529043B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electronic odometer mounted on a vehicle that displays the cumulative mileage.

(Prior Art) An electronic odometer that indicates the cumulative mileage of a vehicle counts the signal from a mileage sensor that converts the number of rotations of a wheel axle, etc., and displays the counted number on an appropriate digital display. In addition to displaying the cumulative mileage from the vehicle, the cumulative mileage data is written in a non-volatile memory as appropriate. However, since there is a limit to the number of times that data can be written to non-volatile memory, the conventional method is to store the value of a preset counter in non-volatile memory when the power is turned off, and then preset the data in the memory to the counter when the power is restarted (Japanese Patent Application Laid-Open No. 1985-1999). No. 84512), a method for counting with a C-MOS counter, writing plus 1 to non-volatile memory using a carry unit every time there is a carry, and constantly supplying power to the C-MOS counter (Japanese Patent Laid-Open No. 57-198810)
(No. 1) and other non-volatile memories, the cumulative mileage data is sequentially updated and written every predetermined distance traveled, and when restarting, all the data in the multiple non-volatile memories is read out and compared to determine the maximum value. (Japanese Unexamined Patent Publication No. 59-196414) etc. have been proposed.

(Problem to be Solved by the Invention) When writing cumulative mileage data into a non-volatile memory, the above-mentioned conventional means certainly reduces the number of times the data is updated to the non-volatile memory; There are still problems with reliability. In other words, when erroneous data is written to a non-volatile memory, the reliability increases as more data is written in order to reliably determine whether or not it is erroneous data. It can be said that there is little data available.

Therefore, when using non-volatile memory, the applicant uses the part normally used as the address on the program as the lower digit of the mileage display, and stores the upper digit in the non-volatile memory, so that it can be used for the specified distance. We proposed an electronic odometer that reduces the number of writes to nonvolatile memory and improves reliability by moving to the next address for each distance and rewriting the data value at the transferred address. (Unexamined Japanese Patent Publication No. 1983-
No. 201312).

The present invention aims to further improve reliability by adding a system for determining a start address at the time of start to the above-mentioned invention.

(Means for solving the problem) The present invention counts signals from a mileage sensor, stores the upper digits of the accumulated mileage value in an attached EEPROM as necessary, and stores the lower digits of the mileage value at the corresponding address. In electronic odometers that use their own values to display cumulative mileage values, move to the next address after each predetermined mileage, and rewrite the data values at the transferred addresses, the odometer is symmetrical at the start. The data written in the position addresses are sequentially compared, and the address where the difference in data values changes is set as a change point, and the data values of the symmetric position addresses are compared a predetermined number of times to confirm the change point. This electronic odometer has a system that starts displaying the mileage and rewriting the data based on the change point after the change.

(Function) The cumulative mileage display and mileage storage system of the present invention uses multiple addresses (for example, addresses 00 and 99) when using EEPROM.
For example, if the cumulative mileage is 123430Km, write the "1234" part as data to "address 30" set as the EEPROM address and leave it as data to display the cumulative mileage. The distance is displayed using the address and the data of the address, and a constant mileage signal is used. In this case, the signal for 1 km is "Address 31."
At the same time, the old data ``1233'' of ``address 31'' is rewritten to plus 1 data to display ``123431Km'', and this process is sequentially repeated. In addition, when the start address search system starts displaying when the power is turned on, if the above-mentioned mileage memory operation is repeated, each address data will, in principle, be separated by a certain difference between addresses 00 and 99. Since the data values differ by 1, it is sufficient to search for the difference at the start of reading and start from the address having the last plus 1 data of the difference. Search "00 address - 99 address""01 address - 98 address"...
Compare the data values of symmetrical position addresses sequentially from both ends of the address, such as "48th address - 51st address" and "49th address - 50th address", find the change point where the difference in data value becomes zero, and then Either perform a confirmation operation by comparing the data values of the position addresses and confirm that the difference is zero, or compare the data values of the symmetric position addresses sequentially starting from the center of the address, and make sure that the difference between the data values is 1. Find the change point corresponding to the two change points, perform a confirmation operation by comparing the data values of the symmetrical position addresses a predetermined number of times and confirm that the difference is 1, and confirm the change point by comparing the data values of the symmetric position addresses a predetermined number of times. The starting address is determined using a predetermined determination method from any address immediately before the change point.

(Example) Next, an example of the present invention will be described based on the drawings.

FIG. 1 is a simple block diagram of the components of the present invention, and FIG. 2 is an EEPROM data table.
Figure 3 is a basic flowchart showing the operation of the present invention, Figure 4 is a flowchart of the search system at the start, and Figure 5 is a simple address diagram showing a method for determining the start address based on the change point. It is a data table.

The basic configuration of the odometer of the present invention is as illustrated in FIG.
It consists of an EEPROM 3 and a display 4. The mileage sensor is installed on the vehicle's wheels or axle, and outputs a pulse signal at each rotation speed, and the CPU 2
This is the distance input. The CPU 2 receives the distance input, counts the number of pulses, writes data to the EEPROM 3 every predetermined distance, and outputs a display to the display 4 in a predetermined manner.

The method of displaying on the display 4 and writing into the EEPROM 3 will be explained based on the address table of FIG. 2 and the flowchart of FIG. 3. The upper digits of the cumulative mileage (for example, in the case of 6 digits, the upper 4 digits or 100 km unit) are written in each address 00 to 99 of the EEPROM 3, and since it is rewritten every 100 km, the data at each address is basically There are only two types (1234 and 1233 in this case), and by using the method described in detail later to find the 30th address of the difference, the data of the address "1234" and the number of addresses of the address "30" are displayed on the display. The cumulative mileage is 123430.
Km" is displayed. While driving, the number of pulse signals from the mileage sensor is counted, and when the number of pulses equivalent to 1 km is counted, "1234" is written to the next address, 31, and "123431 Km" is displayed, and this is repeated sequentially. It is something.

First, a starting address retrieval system for calculating the mileage from the EEPROM 3 will be described below based on the flowchart illustrated in FIG.

When the ignition switch is turned on, "99 address - 00 address" and "98 address - 02 address" are displayed as shown in Figure 2.
The data values are compared sequentially from both ends of the address, and the two symmetrical points where the difference in the data values becomes zero are determined as the change point α ("address 31 - address 68"). Further, the data values are compared, and if the numerical data of the symmetrical position address becomes zero five times or more, the corresponding change point is confirmed to be the correct change point α. If the numerical data of the symmetric position address is not zero during the confirmation operation, it is determined whether there are many combinations A where the difference in data values is zero or there are other combinations B.
Determine whether there is a majority, and if there are many combinations of zeros based on the principle of majority voting, determine the change point as correct,
If this is not the case, the change point α is assumed to be due to incorrect data, and the search is restarted from the symmetrical position address one position inside the change point α.
After confirming the correct change point α, the start address β must be determined, but as illustrated in Figure 5, when the change point α is correct, there are two relationships between the position of the start address β and the change point α. (Case 1 and Case 2) may occur. Then, when the change point α is confirmed, the larger value (data value) C when the difference in data values is 1 is compared with the data value D at the change point, and when C=D, Case 2
Then, the high address of the change point α is determined as the start address β, and when C≠D, it is determined as case 1 and the address immediately before the low address of the change point is set as the start address β. It is.

Note that the above-mentioned starting address search system starts from both ends of the symmetrical position address, that is, the combination of "addresses 99-00," but it starts from the center of the symmetrical position address, that is, the combination of "addresses 50-49." Therefore, a method may be adopted in which the point at which the difference in data values becomes 1 is set as the point of change. Furthermore, the symmetrical location address is not specified as a symmetrical location from all addresses, such as "00 address - 99 address", "01 address - 98 address", etc., as described above, but is a search range that is arbitrarily determined, for example, all the addresses. You can divide the address into two and create combinations such as symmetrical positions in the first half such as "00 address - 49 address", "01 address - 48 address"...
Range excluding some addresses For example, "00 to 89
This is done by combining the symmetrical position address in "address",
If the change point α cannot be found within the range, a method of searching for data values of remaining addresses may be employed.

Furthermore, in the embodiment described in detail above, the display unit is 1 km and the addresses from 00 to 99 are set. However, the present invention is not limited to the above embodiment, and the display unit is 0.1 km. Also good, also said 100
Instead of setting 1 address, set 50 addresses such as 00, 02, 04...96, 98 and use memory to set the display unit to 0.2Km or 2Km, or set the appropriate number of addresses. may be set.

In addition, if the change point α is close to the end of the search, for example, when searching from both ends of the symmetric position address, "46
Address - 53'', the above-mentioned confirmation operation cannot be performed, so in this case, if there is no other change point, the change point is assumed to be correct, and other change points determined to be incorrect data due to the confirmation operation If the value does not exist, an appropriate determination means may be added, such as determining by majority vote of all data.

(Effect of the invention) The present invention provides an electronic odometer that uses EEPROM.
It is equipped with a search system that writes only the high-order digits of the mileage as data to each address, displays the low-order digits using the address itself, and identifies the starting address by comparing the numerical data of symmetrical position addresses. Because the address is used, the number of EEPROM write updates decreases, and when specifying the start address,
Even if erroneous data exists, the correct restart address can be easily and remotely found, and the reliability of the odometer value is improved.

[Brief explanation of the drawing]

The figures show an embodiment of the present invention, and Fig. 1 is a simple block diagram of the constituent members. Fig. 2 is an EEPROM.
FIG. 3 is a flowchart showing the basic operation. FIG. 4 is a flowchart for retrieval at the time of restart. FIG. 5 is a simple address data table showing the relationship between change points and start addresses. 1 is mileage sensor, 2 is CPU, 3 is
EEPROM, 4 is the display, α is the change point, β is the start address.

[Claims]

1. A gap between an origin detection element that reads origin position information recorded on a magnetic recording medium, a displacement detection element that reads position information recorded on the magnetic recording medium at regular intervals, and the magnetic recording medium is electrostatically removed. A magnetoresistive sensor for a magnetic encoder, characterized in that a gap detection electrode for detecting based on capacitance is provided on the same substrate by a magnetoresistive element whose specific resistance value changes according to changes in the magnetic field. .