JPS61108912A - Odmeter for automobile - Google Patents

Abstract

PURPOSE:To prevent data in a non-volatile memory from the generating an error by forming a traveling distance calculating means, the non-volatile memory, a traveling distance data updating means, a power supply circuit, a switching means, a power supply limiting means, etc. CONSTITUTION:A pulse signal from a car speed sensor 1 is counted up by the traveling distance calculating means 2. Traveling distance data are stored in the non-volatile memory 3 and applied to the means 2. Every time when the counted distance reaches a prescribed distance, the updating means 4 updates the traveling distance data stored in the memory 3. Even if an ignition switch 5 is opened, electric power is selectively supplied by a power supply circuit 6 without being passed through the switch 5. If the opening of the switch 5 is detected at the updating of the data, the switching means 8 is driven by a power supply control means 7 during the updating of the data to supply power from the battery 9 mounted on a car to a power supply circuit 6. Even if the switch 5 is opened, the data in the memory 3 can be updated and no error is generated in the data of the memory 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automobile odometer that integrates the distance traveled by a vehicle and displays the total distance traveled.

[Conventional technology]

Conventionally, this type of device uses a non-volatile memory that stores mileage data without power supply in order to electronically store the mileage of a car, and when the ignition switch is opened or the battery is replaced. The system also prevents mileage data from being deleted.

[Problem that the invention seeks to solve]

By the way, in order to write data into such a nonvolatile memory (to update data), a voltage necessary for the data update is applied to the nonvolatile memory during the update. Since a power supply circuit for applying such voltage requires a large current, power is supplied from the vehicle battery only when the vehicle is operated, that is, when the ignition switch is closed.

Therefore, if the mileage data in the nonvolatile memory is updated every time the car travels a predetermined distance,
By chance, I updated the data in the non-volatile memory after turning on the ignition switch.

If this is attempted, there is a problem in that the power supply circuit is not supplied with power from the on-vehicle battery, making it impossible to update data in the nonvolatile memory, resulting in errors in the data in the nonvolatile memory.

The present invention has been made in view of the above-mentioned problem, and in a device that updates data in a non-volatile memory every time the vehicle travels a predetermined distance, it is possible to update the data even when the ignition switch is opened, thereby updating the data in the non-volatile memory. This is to prevent errors from occurring.

[Means for solving problems]

In order to achieve the above-mentioned technical problem, the present invention includes a vehicle speed sensor that generates a pulse signal according to the traveling speed of the vehicle, and a vehicle speed sensor that counts the pulse signals from this vehicle speed sensor and calculates the traveling distance, as shown in FIG. a mileage calculation means for calculating, a display means for displaying the mileage calculated by the mileage calculation means, and a non-volatile storage of the mileage data without power supply;
a non-volatile memory that provides mileage data to the mileage calculating means; and updating the mileage data stored in the non-volatile memory each time the distance counted by the mileage calculating means reaches a predetermined distance. a power supply circuit that receives power supply from an in-vehicle battery via an ignition switch and applies voltage necessary for updating data in the non-volatile memory to the non-volatile memory; a switch means for selectively supplying power to the power supply circuit; and when the update means detects that the ignition switch is open when updating data, the switch means is actuated during the data update so that the vehicle-mounted The present invention is characterized by comprising a power supply control means for causing the power supply circuit to receive heavy power from the buffer battery.

〔Effect of the invention〕

As described above, when updating data in the nonvolatile memory after the ignition switch is turned on, the present invention operates the switch means to supply power from the vehicle battery to the power supply circuit, thereby updating the data in the nonvolatile memory. Since the necessary voltage is applied to the ignition switch, the data in the non-volatile memory can be updated even after the ignition switch is opened, which is an excellent feature that prevents errors in the data in the non-volatile memory. have an effect.

〔Example〕

The present invention will be described below with reference to embodiments shown in the drawings.

In Figure 2, 1 is a vehicle speed sensor that generates a pulse signal according to the traveling speed of the vehicle, and 2 is a microcomputer (hereinafter referred to as a microcomputer) that counts the pulse signals from this vehicle speed sensor and performs processing such as calculating the travel distance. , 2a is a RAM that stores mileage data; 3 is a display unit that displays the mileage based on the mileage data stored in the RAM 2a;
4 is a non-volatile memory (e.g. EEPROM) that updates the data every time the microcomputer 2 counts a predetermined distance and stores the mileage data in a non-volatile manner; 5 is an in-vehicle battery;
6 is an ignition switch; 7 is a microcomputer power supply circuit for supplying power to the microcomputer 2; 8 is a nonvolatile memory power supply circuit that applies voltage necessary for updating data in the nonvolatile memory 4 to the nonvolatile memory; 9 is a nonvolatile memory power supply circuit; This is a switch circuit (consisting of transistors, etc.) for selectively supplying power from the vehicle battery 5 to the nonvolatile memory power supply circuit 8.

The operation of the above configuration will be explained. FIG. 3 is an operation flowchart showing the operations and arithmetic processing of the microcomputer 2.

The microcomputer 2 detects the closing of the ignition switch 6 and executes the arithmetic processing shown in FIG.

At the start of this calculation process, first read the distance data stored in the non-volatile memory 4, and then
Store in AM2a. Thereafter, a display signal is generated on the display unit 3 to display the distance traveled based on the distance data stored in RAM 2 and a. This causes the display unit 3 to display the distance traveled.

Next, the pulse signals from the vehicle speed sensor 1 are counted, and it is determined whether the counted value has reached a value corresponding to 1 km. When it is determined that the count value has reached a value corresponding to lkm, the data stored in the RAM 2a is updated by an amount corresponding to lkm.

Similarly, the mileage data in the non-volatile memory 4 is also 1k
The update operation is started so as to update by the amount corresponding to m. Although not shown in the calculation flowchart of FIG. 3, an update flag is set during the update operation, and the update flag is reset when the update is completed. In the update operation, it is determined whether or not the ignition switch 6 is off, and if the ignition switch 6 is on, the data is updated, and if the ignition switch 6 is off, the switch circuit 9 is turned off. Turn it on to update data. Therefore, when the ignition switch 6 is on, the nonvolatile memory power supply circuit 8 receives power from the vehicle battery 5 via the ignition switch 6, and when the ignition switch 6 is off and the switch circuit 9 is turned on, the nonvolatile memory power supply circuit 8 receives power from the vehicle battery 5. Power is supplied from the battery 5 via the switch circuit 9. Therefore, when updating data to the nonvolatile memory 4, the voltage necessary for updating the data can be applied from the nonvolatile memory power supply circuit 8 to the nonvolatile memory 4.

Then, when the data update is completed and the update flag is reset, it is determined whether the data update is complete. Next, it is determined whether the ignition switch 6 is off, and if the ignition switch 6 is on, the distance counting display operation is restarted, and if the ignition switch 6 is off, the switch circuit 9 is turned off. state, and the power supply to the nonvolatile memory power supply circuit 8 is stopped.

In the above embodiment, the data in the nonvolatile memory 4 is updated every time the vehicle travels, but the data may be updated at a value other than 1k11, for example, every 1Qkm.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIG. 3 is a calculation flowchart showing the calculation processing of the microcomputer in FIG. 1...Vehicle speed sensor, 2...Microcomputer, 3...Display section. 4... Nonvolatile memory, 5... Vehicle battery, 6.
...Ignition switch, 8...Power supply circuit for nonvolatile memory, 9...Switch circuit.

Claims (1)

[Scope of Claims] A vehicle speed sensor that generates a pulse signal according to the traveling speed of the vehicle; a mileage calculation means that counts the pulse signals from the vehicle speed sensor and calculates the distance traveled; and the mileage calculation means. a display means for displaying the mileage calculated by the method; and a display means for storing the mileage data in a non-volatile manner without power supply;
a non-volatile memory that provides mileage data to the mileage calculating means; and updating the mileage data stored in the non-volatile memory each time the distance counted by the mileage calculating means reaches a predetermined distance. a power supply circuit that receives power supply from an on-vehicle battery via an ignition switch and applies voltage necessary for updating data in the non-volatile memory to the non-volatile memory; a switch means for selectively supplying power to the power supply circuit; and when the update means detects that the ignition switch is open when updating data, the switch means is actuated during the data update so that the vehicle-mounted An automotive odometer comprising: power supply control means for supplying power from a battery to the power supply circuit.