JPH06118089A - Car speed display device - Google Patents

Abstract

PURPOSE:To display corrected car speed by turning on a power switch when an edge of a car speed pulse signal is detected, turning off the power switch when pulse is not input for the predetermined time, and calculating correction coefficient by running the known distance. CONSTITUTION:A pulse edge detection circuit 3 detects a front edge of a car speed pulse signal from a pulse generating circuit 2, and a timer circuit 4 sets the predetermined time at every time when the circuit 3 detects signal to start measurement of time. While the interval of edge signal is below the predetermined time, time circuit 4 continues to set the time and sends an ON signal to a power switch circuit 5. When a car almost stops and the interval of edge signal exceeds the predetermined time, the circuit 4 resets and sends an OFF signal to the circuit 5 to prevent waste powder consumption. When a car runs and an operation start and end switch 9 is pressed at the start and end points of running on the predetermined distance, a correction coefficient calculation section 8 calculates a correction coefficient and sends it to a car speed calculation section 7. The calculation section 7 corrects the value calculated by a car speed pulse and displays it in a car speed display section 6. Consequently, it is possible to display accurate car speed even when a tire wheel which has different diameter from a pure tire wheel is mounted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-vehicle vehicle speed display device.

[0002]

2. Description of the Related Art Recently, vehicle-mounted vehicle speed display devices for digitally displaying vehicle speed have become widespread. Such a vehicle speed display device obtains vehicle speed data by converting the rotational speed of the tire wheel into the number of vehicle speed pulses per unit time,
This vehicle speed data is displayed on the digital display.

Such a vehicle speed display device naturally requires a power supply for driving the display circuit, and
A manual power switch is installed in the driver's seat as an accessory. However, if the user forgets to turn off the power switch of the display circuit and leaves the vehicle for a long time, the battery voltage may drop, and in the worst case, the vehicle may not be able to restart.

Further, the type of vehicle speed pulse of the vehicle speed display device of the currently marketed vehicle is different depending on the vehicle type and the manufacturer, and a normal vehicle has 2 to 8 pulses per one rotation of the speed meter cable. You have selected one of the

Therefore, when the speed of a vehicle is measured by the vehicle speed pulse, the form of the vehicle speed pulse of the vehicle must be checked one by one. Further, when a non-genuine tire wheel is mounted on the vehicle, the outer diameter of the tire wheel changes, so that the accurate vehicle speed cannot be displayed.

[0006]

SUMMARY OF THE INVENTION The present invention eliminates the above-mentioned drawbacks of conventional vehicle speed display devices, in that the power switch of the display circuit is automatically turned on when the vehicle starts, and the power switch is automatically turned on when the vehicle is stopped. One of the challenges is to realize a vehicle speed display device that turns off automatically.If the vehicle speed pulse format is different or if a different tire wheel is installed, the vehicle speed data calculated from the vehicle speed pulse is used. Another task is to make a correction so that the correct vehicle speed can be displayed.

[0007]

In order to solve the above first problem, a vehicle speed display device according to the present invention comprises means for calculating a vehicle speed using a vehicle speed pulse and vehicle speed display for digitally displaying the calculated vehicle speed. Means, the means for detecting the edge of the vehicle speed pulse, and the power switch of the vehicle speed display means when the edge of the vehicle speed pulse is detected are turned on, and when the vehicle speed pulse is not input for a predetermined time, the power switch of the vehicle speed display means is turned on. And means for turning it off.

In order to solve the above-mentioned second problem, the vehicle speed display device according to the present invention causes the vehicle to travel a known distance, and the speed calculated by the known distance is displayed on the vehicle speed display means. And a correction means for calculating a correction coefficient for correcting the vehicle speed value calculated by the vehicle speed calculation means. The correction means includes a correction coefficient calculation means,
A switch for instructing the start and end of calculation of the correction coefficient calculation means is provided, and a memory for storing the correction coefficient is provided.

[0009]

In the vehicle speed display device having the above-described structure, first, when the leading edge of the vehicle speed pulse signal first generated by the start of the vehicle is detected by the edge detection means, the power switch of the vehicle speed display means is turned on, The vehicle speed is displayed.

After that, since the vehicle speed pulse interval is smaller than the predetermined time T until the vehicle stops, the power switch of the vehicle speed display means continues to be in the ON state. During this time, the vehicle speed is displayed on the vehicle speed display means. However, when the vehicle is stopped, the next vehicle speed pulse cannot be detected even if the predetermined time T has elapsed from the detection of the vehicle speed pulse signal. At this time, it is considered that the vehicle is stopped, and the power switch of the vehicle speed display means is turned off to turn off the vehicle speed display.

Further, the vehicle is run for a known distance by using a roadway or the like in which the distance is calculated in advance, and the correction coefficient calculation means is operated while appropriately turning on / off the correction coefficient calculation start and end switches. A correction coefficient is calculated so that the speed calculated by the known distance is displayed on the vehicle speed display means. When the known vehicle speed is displayed, the correction coefficient is stored in the memory, and thereafter, the vehicle speed data corrected by the correction coefficient is displayed by the vehicle speed display means.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings. The vehicle speed display device according to the present invention is shown in FIG.
As shown in,
The vehicle rotation detecting unit 1 for detecting the rotation of the vehicle, the pulse generating circuit 2 for generating the speed pulse, the pulse edge detecting circuit 3 for detecting the edge of the vehicle speed pulse, and the timer circuit 4 for measuring a predetermined time from the detection of the edge. A power switch 5 that is turned on / off by the timer circuit 4, a vehicle speed display unit 6 that is supplied with power from the power switch 5 and digitally displays the vehicle speed, and a vehicle speed is calculated based on the output of the pulse generation circuit Vehicle speed calculation unit 7 for outputting the result to the vehicle speed display unit 6
And a correction coefficient calculation unit 8 for calculating a correction coefficient for the vehicle speed based on the output of the pulse generation circuit 2 and a known vehicle speed, and a correction coefficient calculation start switch 9 for controlling the operation of the correction coefficient calculation unit 8. .

It should be noted that the vehicle rotation detecting section 1 which is preliminarily installed in the vehicle is shown in FIG.
As shown in (A), a signal having a higher frequency is output as the vehicle speed is higher, and the pulse generation circuit 2 limits the signal output from the vehicle rotation detection unit 1 at a predetermined threshold level. A vehicle speed pulse signal as shown in 2 (B) is generated.

As can be seen from FIG. 2B, when the vehicle speed is low, the pulse width of the vehicle speed pulse signal is large and the pulse interval is wide. As the vehicle speed increases, the pulse width decreases and the pulse interval also decreases.

The pulse edge detection circuit 3 detects the leading edge of the vehicle speed pulse signal output from the pulse generation circuit 2 as shown in FIG. 2 (C). The timer circuit 4 sets a predetermined time T each time the edge signal output from the pulse edge detection circuit 3 is input (t0, t1, ... tm),
Start timing.

The time T set in the timer circuit 4
Is appropriately selected based on the vehicle speed pulse signal interval when the vehicle is stopped. Therefore, the timer circuit 4
As shown in FIG. 2D, when the first edge signal is detected t
After the set state is 0, the set state is continued while the edge signal interval is smaller than T.

Then, at the time tn when the next edge signal is not detected even when the time T has elapsed from the time tm when the previous edge signal was detected, the timer circuit 4 reaches a count of 0 and is reset.

The timer circuit 4 sends an ON signal to the power switch 5 in the set state, and sends an OFF signal to the power switch 5 in the reset state. The power switch 5 energizes the power supply to the vehicle speed display unit 6 when an ON signal is input from the timer circuit 4, and shuts off the power supply to the vehicle speed display unit 6 when an OFF signal is input.

As a result, the power switch 5 is turned on as shown in FIG.
As shown in FIG.
Is turned off at. As described above, when the interval of the edge pulse becomes longer than the predetermined value, it is regarded as the stop of the vehicle and the power supply of the vehicle speed display unit 6 is cut off to turn off the display. This prevents unnecessary power consumption.

The vehicle speed display unit 6 digitally displays the vehicle speed based on the vehicle speed data from the vehicle speed calculation unit 7 when the power is on. The vehicle speed calculation unit 7 calculates the vehicle speed by counting the number of vehicle speed pulses output from the pulse generation circuit 2 per unit time, creates display data, and sends it to the vehicle speed display unit 6.

The correction coefficient calculation unit 8 and the correction coefficient calculation start / end switch 9 are provided for the vehicle speed when the form of the vehicle speed pulse is unknown, or when the vehicle is equipped with a tire wheel having an outer diameter different from that of a genuine product. The vehicle speed value calculated by the vehicle speed calculation unit 7 is corrected as follows so that is correctly displayed.

When the vehicle is actually run and runs a predetermined distance, for example, 500 m, the correction coefficient calculation start switch 9 is pushed at the starting point. Then, when the vehicle has traveled a distance of 500 m, the correction coefficient calculation start and end switch 9 may be pressed.

When the correction coefficient calculation start / end switch 9 is turned on, the correction coefficient calculation unit 8 calculates a correction coefficient such that the distance calculated from the total vehicle speed pulse number at that time becomes 500 m. The calculation of the correction coefficient is continued until the traveling distance reaches 500 m by appropriately turning on / off the correction coefficient calculation start / end switch 9.

The correction coefficient calculated by the correction coefficient calculation unit 8 is output to the vehicle speed calculation unit 7. Therefore, the vehicle speed calculation unit 7
The correction coefficient is stored in the memory 10, and thereafter, the vehicle speed data calculated based on the vehicle speed pulse from the pulse generating circuit 2 is corrected by the correction coefficient, and the corrected vehicle speed data is output to the vehicle speed display unit 6. Display it.

[0025]

As described above, according to the present invention,
The power supply of the vehicle speed indicator is turned on when the vehicle starts and turned off when the vehicle is stopped, which saves power supply power. In the case of vehicles equipped with different tire wheels, the vehicle speed value calculated on the basis of the vehicle speed pulse is corrected by the correction coefficient. Therefore, even in the above case, an accurate vehicle speed can be displayed.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a vehicle speed display device according to the present invention.

2 is a timing chart showing output signals of various parts of the vehicle speed display device of FIG.

[Explanation of symbols]

 1 vehicle rotation detection unit 2 pulse generation circuit 3 pulse edge detection circuit 4 timer circuit 5 power switch 6 vehicle speed display unit 7 vehicle speed calculation unit 8 correction coefficient calculation unit 9 correction coefficient calculation start and end switch 10 memory T predetermined time interval t0, t1, tm, tn time

Claims (4)

[Claims] 1. A means for calculating a vehicle speed using a vehicle speed pulse signal, a vehicle speed display means for digitally displaying the calculated vehicle speed, a means for detecting an edge of the vehicle speed pulse signal, and an edge for the vehicle speed pulse signal. A vehicle speed display device for turning on the power switch of the vehicle speed display means when detected, and for turning off the power switch of the vehicle speed display means when the vehicle speed pulse is not input for a predetermined time. . 2. A vehicle speed value calculated by the vehicle speed calculation means is corrected so that the vehicle travels a known distance and the speed calculated by the known distance is displayed on the vehicle speed display means. The vehicle speed display device according to claim 1, further comprising a correction unit that calculates a correction coefficient. 3. The correction means includes a correction coefficient calculation means,
The vehicle speed display device according to claim 2, further comprising a switch for instructing start and end of calculation of the correction coefficient calculation means. 4. The vehicle speed display device according to claim 3, wherein the correction means includes a memory that stores a correction coefficient.