JP2001221663A - Indicating instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide indicating instrument, capable of obtaining indicating behavior of a measured value almost, following actual state especially n the vicinity of a measured lower limit value. SOLUTION: A present constructive pulse width Wan (unit: ms), used as a signal for displaying a present car speed, is calculated by formula: Wan=[Wt(n)+Wt(n-1)+Wt(n-2)+,..., +Wt n-(N-1)}]/N [where, Wt(n) is the pulse width of pulses actually detected at a time tn, Wt(n-1) is the pulse width of pulses, for example, immediately prior to the past pulses, Wan is the present constructive pulse width and N is the present and past prescribed number of times]. Here, the pulse widths [Wt(n-1), Wt(n-2), Wt n-(N-1)}] of the past pulses at a time reaching, such a stat that present pulses, are detected at a time tn for the first time, after the succession of a state where the past pulses are not detected (S) is substituted for the pulse width corresponding to the set time of a timer (S4-S5).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an indicating instrument such as a speedometer.

[0002]

2. Description of the Related Art A traveling speed of a vehicle (hereinafter referred to as a vehicle speed).
For example, a speedometer that detects and displays a vehicle has, for example, a plurality of magnets disposed on an axle or the like, and a vehicle speed sensor including a magnetic sensor disposed at a vehicle body position near the magnets. In this case, a change in magnetic field is detected as a pulse by a vehicle speed sensor, and the pulse width of the pulse is converted into a vehicle speed and displayed on a display meter.

At this time, in the pulse generation pattern shown in FIG. 7, if the vehicle speed is sequentially displayed using the pulse width of each generated pulse (actual pulse), various errors such as installation dimensional errors of the magnet and the vehicle speed sensor are obtained. Depending on the cause, an accurate vehicle speed cannot be displayed, and when these error elements and noise are included, the display value of the vehicle speed may be greatly disturbed.

For this reason, conventionally, a moving average value calculated from the pulse widths of a predetermined number of current and past pulses detected by a vehicle speed sensor within a set time of a timer of a microcomputer is regarded as a current pulse width ( Hereinafter, there is a case where the vehicle speed is calculated from the current pulse width and the current vehicle speed is displayed on the display meter as the current vehicle speed.

[0005] For example, the pulse width of a pulse actually detected at the time tn is Wt _(n) (unit: ms, the same applies hereinafter). For past pulses, for example, the pulse width of the immediately preceding pulse is Wt _{(n-1). ),} and the current deemed pulse width is Wa _n, when present and past a predetermined number of times is n, the pulse width Wa _n assumes the current is calculated by the following equation. Here, the predetermined number N is an arbitrary number of pulses set for pulses counted within the set time of the timer.

[0006] _{Wa n = (Wt (n)} + Wt (n-1) +
_{Wt (n-2) + ...} + Wt (n- (N-1))) / N Therefore, the pulse width _Wt n of pulses actually detected the current assumes a pulse width _{Wa n (Wt (n),} Wt
_(N-1) ...) And the relationship shown in FIG.
The pulse width Wa ₅ considers the current at time t ₅ when the when the predetermined number of times N = 3 is calculated by the following equation,
In this case, larger than the pulse width Wt ₅ of the current pulse.

[0007] _{Wa 5 = (Wt 5 + Wt} 4 + Wt 3) / 3 Note that, displays an exaggerated change in pulse width for convenience pulse generation pattern described in Figure 7, the calculation of the current assumes a pulse width Wa _n Although the method is shown in a simplified manner, normally, the predetermined number of times N is actually performed, and the current vehicle speed is determined by pulse data for a total of four periods.

By the way, in an extremely low speed region near 0 km / h,
The pulse width Wt of the above detection pulse _(N)Is infinite
You. In this case, the infinite pulse width Wt is used as it is._(N)To
Storing in memory and counting is a waste of memory.
Requires a timer with a large number of bits
Cost. On the other hand, the speedometer
The displayed vehicle speed is originally stable during running, that is,
Accurate display in the area of speed is required,
For this, a rather small pulse width Wt_(N)Exactly
A timer that can count the number is required.

In consideration of the above points, for example, a timer having a set time of 200 ms (vehicle speed of about 3.6 km / h) is employed, and the pulse width of the pulse exceeds the set time of the timer when the vehicle speed is low. For the minute (unmeasurable pulse), an overflow process is performed, for example, the pulse width is uniformly counted as 2 s.

[0010]

However, in the case of the above-mentioned conventional speedometer, when the vehicle is gradually accelerated from the initial speed of zero at the time of starting, as shown in FIG.
The determined vehicle speed (indicated as the detected vehicle speed in FIG. 8) corresponding to the current non-existing pulse width (determined pulse width) rapidly rises during the start elapsed time of about 2.0 s to about 2.5 s, and Obviously, the following of the vehicle speed is displayed with a large delay.

This is because the state in which the actual vehicle speed is extremely low immediately after the vehicle starts, and the pulse width of the generated pulse (indicated as the pulse width of the vehicle speed pulse in FIG. 8) requires overflow processing. And the time interval of pulse detection becomes extremely long, and as a result, a state equivalent to substantially no pulse detection occurs, and a state where the current pulse width is almost zero continues, and the generated pulse The pulse width corresponding to the vehicle speed of a certain magnitude is counted only when the pulse width of the pulse width falls within the set time of the timer.

[0012] As described above, the set time of the timer is, for example, about 200 ms. Therefore, in this case, the pulse width of the pulse generated due to a low actual vehicle speed exceeds 200 ms. (For a vehicle speed of less than about 3.6 km / h), the pulse width is 2 s (about 0.4 k for the vehicle speed) by overflow processing.
m / h).

[0013] The display vehicle speed that is actually visually recognized by the driver is basically a mechanism in which the above-mentioned determined vehicle speed is displayed almost as it is. In practice, a soft damper or an oil damper is used to control the movement of the display needle so that the movement of the display needle is slow and smooth.

On the other hand, at the time of stop, there is a similar problem as shown in FIG. 9, for example.

As described above, it is apparent that it is not preferable that the speed is displayed in a state where the speed following the actual vehicle speed is greatly delayed in the acceleration / deceleration process at the time of starting or stopping.

The above-described indication behavior of the measured value dissociated from the actual state in the vicinity of the lower limit of measurement exists, and the phenomenon of giving a sense of incongruity to a person who visually recognizes the indication behavior is not limited to the above speedometer alone. .

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide an indicating instrument capable of obtaining an indicating behavior of a measured value substantially following the actual state in the vicinity of a lower limit of measurement.

[0018]

The indicating instrument according to the present invention comprises a pulse width counting means for counting a pulse width of an input pulse, and a plurality of counting results of the pulse width counted by the pulse width counting means. Mean value calculating means for calculating an average value, indicating value calculating means for calculating an indicating value according to the average value, and calculating the average value according to the counting result of the pulse width counted by the pulse width counting means Means for correcting the average value calculated by the means. Here, the indicating instrument preferably refers to a speedometer, but is not limited thereto, and includes a general indicating instrument such as a tachometer as long as the effects of the present invention can be obtained.

Thus, the indicating value of the indicating instrument uses an average value of a plurality of values and further corrects the average value.
Even if a pulse due to noise is generated, the influence thereof is reduced, and in particular, a measurement value indicating behavior almost following the actual state can be obtained in the vicinity of the measurement lower limit value, and the viewer does not feel uncomfortable.

Further, the indicating instrument according to the present invention is characterized in that the average value correcting means corrects the average value by replacing a past pulse width count result with a predetermined value.

For example, when a speedometer is used as an indicating instrument, the speedometer calculates a moving average value calculated from a vehicle speed sensor and a pulse width of a predetermined number of current and past pulses detected by the vehicle speed sensor. In a speedometer having a current pulse width and an arithmetic processing / control device for calculating the vehicle speed from the current pulse width, the arithmetic processing / control device detects only pulses generated within a set time of a timer. When the current pulse is detected for the first time after the state where the past pulse is not detected, the pulse width corresponding to the set time of the timer is used as the pulse width of the pulse for which the past pulse is not detected. Such a configuration is preferable.

Here, the predetermined number of times for calculating the moving average value can be set as appropriate. Further, the set time of the timer can be set as appropriate in accordance with the lower limit of the vehicle speed that needs to be measured.

According to the structure of the invention described above, for example, during the shifting process of the vehicle, the speedometer matches the driver's sense near the region where the pulse cannot be measured by the timer, that is, at an extremely low speed, and sets the vehicle speed close to the actual condition. It is possible to display an appropriate vehicle speed while reducing the influence of noise. This effect can be obtained particularly suitably in the acceleration process at the time of starting.

In the indicating instrument according to the present invention, the average value correcting means corrects the average value by replacing the current pulse width count result with a value obtained by multiplying a past pulse width count result by a predetermined coefficient. It is characterized by doing.

For example, when a speedometer is used as an indicating instrument, the speedometer uses a vehicle speed sensor and a moving average value calculated from current and past pulse widths detected by the vehicle speed sensor for a predetermined number of times. In a speedometer equipped with an arithmetic processing and control device that calculates the vehicle speed from the current pulse width as an assumed pulse width, the arithmetic processing and control device detects only pulses generated within the set time of the timer, When the current pulse is not detected for the first time after the state where the pulse is detected continues, the pulse width of the current pulse is used as the pulse width of the current pulse corrected by a predetermined correction coefficient. Such a configuration is preferable.

Here, the correction by the predetermined correction coefficient is performed in order to make the change of the current pulse width slow and smooth even when the vehicle speed suddenly changes. It can be determined individually as appropriate according to the traveling environment, the characteristics of the speedometer, and the like.

According to the configuration of the invention described above, the speedometer matches the driver's feeling and displays the vehicle speed close to the actual condition near the region where the pulse cannot be measured by the timer during the shifting process of the vehicle, that is, at an extremely low speed. In addition, an appropriate vehicle speed can be displayed by reducing the influence of noise. This effect can be obtained particularly suitably in the deceleration process at the time of stopping.

Note that a pulse having a pulse width exceeding the set time of the timer originally cannot be expected to measure the vehicle speed with high precision and accuracy.
In the present invention, there is no problem at all in measuring the pulse whose pulse width falls within the set time of the timer and eliminating the overflow processing.

Further, the indicating instrument according to the present invention calculates a pulse width counting means for counting a pulse width of an input pulse, and calculates an average value of a plurality of counting results of the pulse width counted by the pulse width counting means. Average value calculating means, an indicated value calculating means for calculating an indicated value according to the average value, and a predetermined coefficient added to the indicated value calculated by the indicated value calculating means after multiplication by a predetermined coefficient Instruction value correcting means for correcting the indicated value by replacing the indicated value with the specified value.

For example, when a speedometer is used as the indicating instrument, the speedometer uses a vehicle speed sensor and a moving average value calculated from the current and past pulse widths detected by the vehicle speed sensor for a predetermined number of times. In a speedometer having an arithmetic processing / control device for calculating a vehicle speed from the current pulse width as an assumed pulse width, the arithmetic processing / control device includes a predetermined correction coefficient for the vehicle speed calculated from the current dummy pulse width. It is preferable to use a value obtained by adding a predetermined value and correcting it after multiplying by.

According to the configuration of the invention described above, the phenomenon that the change of the indicated value near the lower limit of measurement of the indicating instrument becomes discontinuous is mitigated, and a smooth change behavior of the indicated value can be obtained. Without giving a sense of incongruity,
For example, it is suitable as a display of an indicating instrument in an extremely low speed range during a shifting process of a vehicle.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment (hereinafter, referred to as an embodiment) of a speedometer as an indicating instrument according to the present invention will be described below with reference to the drawings.

First, the device configuration of the speedometer according to this embodiment will be described with reference to the schematic block diagram of FIG.

The speedometer 10 includes a vehicle speed sensor 12 and an arithmetic processing / control device 14, and further includes a meter indicating section 16 as a vehicle speed display.

Since the vehicle speed sensor 12 is the same as that described in the conventional example, the description is omitted here.

The arithmetic processing / control device 14 includes the vehicle speed sensor 1
Waveform shaping section 18 for shaping the waveform of the pulse output from 2
And a pulse width measuring unit (pulse width counting means) 20 for measuring (counting) the pulse width of the pulse whose waveform has been shaped, a filter processing unit 22 for removing noise components, and a pulse width for converting the pulse width to vehicle speed. A vehicle speed conversion unit 24, a cross coil output conversion unit 26 that converts an input signal from the pulse width / vehicle speed conversion unit 24 into an output signal to the cross coil, and a vehicle speed of the speedometer based on an output signal from the cross coil output conversion unit 26 And a cross coil 28 for controlling the display hand. Note that the arithmetic processing / control device 14 is provided separately or with a microcomputer 30 specially provided for the speedometer 10.
To perform arithmetic processing and control (average value calculation means, average value correction means).

The meter indicating section 16 is an analog type comprising a display plate (not shown) engraved with a vehicle speed scale and a pointer for indicating a predetermined scale on the display panel. The pointer is rotatable by an axis. Supported by Further, the cross coil 28 composed of two sets of coils surrounding the rotor magnet fixed to the shaft is arranged orthogonally to each coil. A change in the output signal to the cross coil applies a rotating magnetic field to the shaft, and the rotation of the shaft rotates the pointer. It should be noted that a soft damper for suppressing a sudden movement of the support needle by electrical control and an oil damper for physically suppressing the movement are provided as appropriate.

The speedometer 1 constructed as described above
The vehicle speed measurement and display mechanism at 0 will be described with reference to FIGS.

FIG. 2 shows a pulse generation pattern in the process of gradually accelerating from an initial speed of zero when starting.

The pulse generation pattern shown in FIG. 2 is obtained after the waveform output from the vehicle speed sensor 12 is shaped by the waveform shaping section 18. Here, the setting time of the timer of the microcomputer 30 for counting the pulse is 200 m.
s.

Initial stage at the time of start (time t _{1 to} t _{7 in} FIG. 2)
Since the vehicle speed is extremely low, the pulse width of the generated pulse is extremely large and overflows more than 200 ms, as described above in the related art, so that the pulse width cannot be detected. Time 2 during that time
Each pulse when it is considered that a pulse is generated once every 00 ms (Wt indicated as a detection pulse in FIG. 2)
The pulse widths of _{1 to 7} ) are set to zero, so that no pulse width is displayed.

Then, as the acceleration proceeds, the pulse width becomes 200
A pulse having a pulse width of ms or less is generated for the first time, and thereafter, a pulse having a pulse width that becomes gradually smaller (Wt ₈ or later) is continuously generated.

Here, the present only pulse width Wa used as a signal for displaying the current vehicle speed every moment.
_n (unit: ms) (not shown) is basically calculated by the same method as described in the conventional example.

That is, the pulse width of the pulse actually detected at the time tn is Wt _(n) , and the pulse width of the previous pulse is, for example, Wt _(n-1) .
And the current deemed pulse width is Wa _n, when present and past a predetermined number of times is N, the current assumes the pulse width W
a _n is calculated by the following equation.

Wa _n = (Wt _(n) + Wt _(n-1) +
Wt _(n−2) +... + Wt _{(n− ( N−1))} ) / N Here, the predetermined number N is the number of pulses counted within the set time of the timer. Similarly, the number is eight (pulse width counting means). In addition, from the viewpoint of the vehicle speed display timing, the counting is performed every half cycle.

By substituting the predetermined number N = 8 into the above equation, the following expression is obtained (mean value calculating means).

Wa _n = (Wt _(n) + Wt _(n-1) +
.. + Wt _(n−7) ) / 8 However, in the present embodiment, unlike the conventional example, after the state where the past pulse is not detected continues (Wt in FIG. 2).
_1-7), the first time when the current pulse has reached the state detected (in FIG. 2, Wt ₈₎ Set the timer for the last minute of the pulse width _(Wt 7 _{~Wt 1)} at time _{t 8} The pulse width is replaced with a pulse width corresponding to time, that is, 200 ms in this case. As a result, the current assumes the pulse width in time t ₈ (determined pulse width) Wa ₈ is determined from the following equation (average value correcting means).

[0048] Wa₈= (Wt₈+200 + ... + 200) / 8 Time t₉Pulse width Wa at present₉Is
Wa₉= (Wt₉+ Wt ₈+200 + ... + 200) / 8
Becomes

Also in the pulse generation pattern shown in FIG. 3 in the process of gradually decelerating from a predetermined vehicle speed at the time of stop, the non-existent pulse width Wan at the time tn is obtained by a basically similar method at the time of starting. .

However, in this case, the current pulse is not detected for the _first time after the state where the past pulse is detected continues (Wt _{1 to 7} displayed as detected pulses at times t _{1 to} t ₇ in FIG. 3). When the state is reached (Wt ₈ ), the pulse width of the current pulse is replaced with the pulse width of the immediately preceding past pulse corrected by a predetermined correction coefficient. Here, the pulse width of the immediately preceding pulse is multiplied by 1.3 as a correction coefficient. By multiplying by this correction coefficient, the change of the pulse width becomes slow and smooth, and the sudden decrease in the display vehicle speed is suppressed. This correction coefficient can be appropriately determined according to the running environment of the vehicle, the characteristics of the speedometer, and the like.

[0051] Thus, the pulse width Wa ₈ currently considered of at time _{t 8 Wa 8 = (1.3 ×} Wt 7 + Wt 7
_{+ Wt 6 + ... Wt 1)} / 8 , and the further current deemed pulse width Wa ₉ at time _{t 9} is _Wa 9 = {(1.
3) ² × Wt ₇ + 1.3 × Wt ₇ + Wt ₇ +... + W
t ₂ ) / 8.

[0052] is calculated by the method described above, using the current deemed pulse width Wa _n, to confirm the determined vehicle speed (conversion), further, every moment by using the determined vehicle speed, the procedure for displaying the current vehicle speed Will be described with reference to the flowchart of FIG.

First, this time (current), the pulse width Wt _n 200 m within 200 ms which is the set time of the timer.
It is determined whether or not a pulse less than s is detected (S1). 20
When there is no detection of the following pulse 0ms replaces actually 1.3 times the value of the pulse width Wt _n-1 pulses in the previous (last just before) is the current is zero pulses of the pulse width Wt _n (S2). Then, the moving average value of the past seven pulse widths and the current pulse width is set to the current determined pulse width (current only pulse width Wa _n ) (S3). On the other hand, if a 200 ms pulse is detected in step 1, it is further determined whether or not the last determined vehicle speed is 3.6 km / h or less (S4).

It is determined whether or not the last determined vehicle speed is not more than 3.6 km / h (S4). If not, the moving average value of the past seven pulse widths and the current pulse width is determined. Is the current determined pulse width (S3). On the other hand, when the last determined vehicle speed is 3.6 km / h or less, the pulse width of the past seven pulses is replaced with 200 ms (S5).
Then, the meter reading of this time continues to be 3.6 km / h
It is determined whether or not this is the case (S6). If the speed is 3.6 km / h or more, the moving average value of the past seven pulse widths and the current pulse width is set as the current determined pulse width (S3). If the meter indication value is not equal to or greater than 3.6 km / h, the meter indication is set to the true 0 km / h position (S7), and the moving average of the past seven pulse widths and the current pulse width is set to the current fixed pulse. The width is set (S3).

In each running pattern, the moving average value of the past seven pulse widths and the current pulse width is used as the current determined pulse width (S3), and a filtering process is performed (S8). The vehicle speed is converted into the determined vehicle speed (S9).

Next, it is determined whether or not the determined vehicle speed is less than 10 km / h (S10). If the determined vehicle speed is less than 10 km / h, the determined vehicle speed is multiplied by a value of 1.5 and further OFFSET (offset value: FIG. 4) to correct the determined vehicle speed (S11).

Here, the coefficient 1.5 for multiplying the determined vehicle speed is an example. By multiplying this coefficient, the meter indicated value changes smoothly in the acceleration / deceleration process in the low speed range at the time of starting or stopping. More consistent with the driver ’s feeling,
It will be close to the actual situation. The tendency is more remarkable at the time of stoppage. At this time, the fixed vehicle speed is set to a coefficient of 1.5.
In order to eliminate the discontinuity of the determined vehicle speed at the point of the determined vehicle speed of 10 km / h, the determined vehicle speed is multiplied by a factor of 1.5, and then OFFSET (offset value) α is set as an example. Add 5 km / h.
That is, the determined vehicle speed (indicated by a solid line in FIG. 10) in the region of 10 km / h or more gradually decreases to 10 km / h.
At the time when m / h is reached (indicated by A1 in FIG. 10), 10 k
The corrected fixed vehicle speed (indicated by the broken line in FIG. 10) multiplied by the coefficient 1.5 in the region less than m / h gradually increases to 1
A difference of 5 km / h from the value at the time of reaching 0 km / h (indicated by A2 in FIG. 10) occurs.
The corrected fixed vehicle speed multiplied by the coefficient 1.5 in the region less than 0 km / h is -5 as OFFSET (offset value) α.
By further adding km / h, the re-corrected fixed vehicle speed in the region of less than 10 km / h (indicated by a dashed line in FIG. 10) becomes the uncorrected fixed vehicle speed (solid line) in the region of 10 km / h or more. And is continuous. In addition, 10
The re-correction confirmed vehicle speed in the area less than km / h is OFF
In FIG. 10 for explaining the significance of SET α, the actual vehicle speed is displayed as a negative value in a range of about 4 km / h or less.
As described above, it is set to the true 0 km / h position after the processing of step 7.

The meter indication value is displayed in correspondence with the final determined vehicle speed determined in the above procedure (not shown).

FIG. 5 shows a case when the vehicle starts moving and FIG. 6 shows a case when the vehicle stops when the vehicle speed and the meter indication change over time determined by the above procedure.

Regarding the case at the time of starting, the vehicle according to the present embodiment shown in FIG. 5 is different from the conventional vehicle shown in FIG. Standing up smoothly. In this case, the speedometer 10 appropriately includes a soft damper and the like.

Similarly, in the case of the stop, FIG.
In this embodiment, the vehicle speed and the meter indication are both reduced smoothly at a time of about 1.5 s without a sudden decrease as in the conventional example shown in FIG.

As described above, according to the speedometer 10 according to the present embodiment, during the shifting process of the vehicle, near the region where the pulse cannot be measured by the timer, that is, at an extremely low speed, the speedometer 10 is suitable for the driver. Therefore, the actual vehicle speed can be displayed. Also, since the moving average value is used as the current pulse width, when noise occurs at extremely low speeds, the effect of the noise is reduced to a maximum of 1 / N, and the effect of the noise is reduced to display an appropriate vehicle speed. can do.

The present invention is not limited to the description of the present embodiment, and 200 ms is uniformly used as the value of the past pulse width at the time of starting when the fixed pulse width is calculated using the moving average value. Instead, an arbitrary value of less than 200 ms or the immediately preceding pulse width may be used, and in this case, multiplication by an appropriate correction coefficient is not excluded. The same applies to the fixed pulse width at the time of stop.

[0064]

According to the indicating instrument of the present invention, the pulse width counting means, the average value calculating means, the indicating value calculating means,
With the average value correction means, even if a pulse due to noise is generated, the influence of the noise is reduced, and in particular, a measurement value indicating behavior almost following the actual state can be obtained near the measurement lower limit value. Does not give a feeling of incompatibility.

According to the indicator of the present invention, the average value correcting means corrects the average value by replacing the past pulse width count result with a predetermined value, or the current pulse width count result. Is replaced with a value obtained by multiplying a past pulse width count result by a predetermined coefficient to correct the average value, so that the effects of the present invention can be suitably achieved.

According to the indicating instrument of the present invention, the indicated value correcting means multiplies the indicated value calculated by the indicated value calculating means by a predetermined coefficient, and then replaces the indicated value with a value obtained by adding a predetermined value to the indicated value. Since the value is corrected, the effects of the present invention can be more suitably achieved.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of an apparatus configuration shown for explaining a configuration of a speedometer according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining a method of calculating a present only pulse width according to the embodiment and is a diagram showing a pulse generation pattern at the time of starting.

FIG. 3 is a diagram for explaining a method of calculating a current non-existent pulse width according to the present embodiment, and is a diagram showing a pulse generation pattern at the time of stop.

FIG. 4 is a flowchart for explaining a procedure until a meter instruction of the speedometer according to the present embodiment is displayed.

FIG. 5 is a diagram showing a vehicle speed when the speedometer according to the present embodiment starts.

FIG. 6 is a diagram showing a vehicle speed when the speedometer according to the embodiment is stopped.

FIG. 7 is a view for explaining a method of calculating a current pulse width in a conventional example, and is a diagram showing a pulse generation pattern during stable running.

FIG. 8 is a diagram showing a vehicle speed when a conventional speedometer starts.

FIG. 9 is a diagram showing a vehicle speed when a conventional speedometer is stopped.

FIG. 10 is a diagram for explaining the significance of the correction of the determined vehicle speed in a region of less than 10 km / h in the speedometer according to the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Speedometer 12 Vehicle speed sensor 14 Arithmetic processing / control apparatus 16 Meter indication part 18 Waveform shaping part 20 Pulse width measurement part 22 Filter processing part 24 Pulse width / vehicle speed conversion part 26 Cross coil output conversion part 28 Cross coil 30 Microcomputer

Claims (4)

[Claims] A pulse width counting means for counting a pulse width of an input pulse; an average value calculating means for calculating an average value of a plurality of counting results of the pulse width counted by the pulse width counting means; An instruction value calculating means for calculating an instruction value according to the average value; and an average for correcting the average value calculated by the average value calculating means according to the result of counting the pulse width counted by the pulse width counting means. An indicating instrument comprising value correction means. 2. The indicating instrument according to claim 1, wherein the average value correcting means corrects the average value by replacing a past pulse width count result with a predetermined value. 3. The average value correcting means corrects the average value by replacing a current pulse width count result with a value obtained by multiplying a past pulse width count result by a predetermined coefficient. The indicating instrument according to 1. 4. A pulse width counting means for counting a pulse width of an input pulse; an average value calculating means for calculating an average value of a plurality of counting results of the pulse width counted by the pulse width counting means; An instruction value calculating means for calculating an instruction value according to the average value; and an instruction value calculated by multiplying the instruction value calculated by the instruction value calculation means by a predetermined coefficient and further adding a predetermined value to the instruction value. And an indicating value correcting means for correcting the value.