JPH0850137A - Speed display, water meter - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain a highly accurate speed indicator and water meter with low current consumption. [Structure] A sampling control unit 2 intermittently activates a sensor 1 that generates a pulse proportional to the amount of movement of the object to be measured, and the sensor output state sampled by the pulse converter 3 is proportional to the amount of movement of the object to be measured. Reproduce the pulse. The arithmetic and control unit 9 stores the interface stored in the storage unit 6.
The count value of the counting unit 5 that has counted the pulses of the constant time designated by the timer 4 is corrected by the previous count value stored in the storage unit 6 and the previous correction value stored and stored in the correction storage unit 7. The moving speed of the measured object proportional to the average pulse speed within the fixed time from the corrected count value and the fixed time designated by the interval timer 4 is corrected and calculated, and displayed on the display unit 8 as the moving speed of the measured object. .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed display device and a water meter.

[0002]

2. Description of the Related Art A water meter is an application of this type of speed display device. FIG. 8 shows that the rotation of an impeller rotating according to the flow velocity is converted into an electric pulse by a rotation sensor using the rotating magnetic field of a magnet provided by the impeller, and the instantaneous flow rate is calculated from the cycle of the electric pulse. Fig. 9 and Fig. 10 are functional block diagrams of the conventional embodiment of the water meter displayed as
FIG. 6 is a diagram for explaining a procedure for calculating and displaying an instantaneous flow rate from a cycle of a rotation pulse.

In these figures, a magnet (11) is attached to the tip of the impeller (10), and the rotation of the impeller (10) is converted into an electric pulse by a rotation sensor (12). The rotation pulse converted into an electric pulse by the rotation sensor (12) is subjected to pulse edge detection by the detection unit (18). The arithmetic control section (19) reads the start time T1 from the timer (20) at which the pulse edge is detected by the detection section (18). When the detection section (18) again detects the pulse edge, the end time T2 is read from the timer (20). In this way, the calculation control unit (19) can obtain the pulse period from the start time T1 and the end time T2, calculate the instantaneous flow rate from the correspondence coefficient with the preset flow rate, and display it on the display unit (8). indicate. By repeating this, the instantaneous flow rate value can be displayed on the display unit (8).

Next, an example of the rotation sensor (12) is shown in FIG. The magnetoresistive element (21) for detecting a magnetic field changes its output voltage centered on the intermediate voltage V / 2 depending on the direction of the applied magnetic field, and is connected to one input of the comparator (23). The other input of the comparator (23) has a resistor (22)
Is connected to the intermediate voltage V / 2. Therefore, when the direction of the applied magnetic field makes one revolution, the comparator (23) outputs two pulses. FIG. 12 shows the output voltage of the magnetoresistive element (21) when the magnetic field applied to the magnetoresistive element (21) makes one revolution, and the output of the comparator (23) at that time.

Next, a specific example regarding the calculation of the instantaneous flow rate will be described. The flow rate per revolution of the impeller (10)
It is assumed that it is rotating at 0.1 l and one rotation / second. Impeller (1
In one rotation of (0), the magnetic field applied to the rotation sensor (12) is
Since it changes 360 degrees, two pulses are output from the rotation sensor (12). Therefore, the pulse period is 0.5 seconds, and the flow rate per pulse is 0.05 l. The detection section (18) detects the pulse edge, the arithmetic control section (19) reads the start time and end time from the timer (20), and the difference is 0.5 seconds. From this, the arithmetic control unit (19)

[0006]

## EQU1 ## The instantaneous flow rate of 0.05 l × 3600 seconds / 0.5 seconds = 360 l / hour can be calculated and displayed on the display unit (8).

[0007]

By the way, although the original function of the water supply meter is to integrate the flow rate, there is a demand for a water supply meter with an instantaneous flow rate display function as one of the multifunctional functions. Such a water supply meter uses a battery as a power source, and it is necessary to have a battery life of a verification valid period (8 years). Therefore, in order to reduce the current consumption, the power supply is intermittently supplied to the magnetoresistive element and its pulse conversion circuit, and the output pulse of the rotation sensor (12) due to the change of the magnetic field is intermittently sampled. Is being detected. However, as shown in FIG. 13, when the rotation sensor (12) is intermittently fed, the pulse period T3 obtained by the intermittent feeding and the original pulse period T4 do not match.

Therefore, the sampling method cannot accurately determine the time from pulse edge to edge, and the instantaneous frequency is calculated by calculating the average frequency from the number of pulses within a certain fixed period. However, when counting the number of pulses within a certain fixed period, an error of one pulse occurs depending on how the measurement section is taken even if the pulse train has a constant period. If the measurement time is sufficiently longer than the pulse period, the number of pulses in that period is also sufficiently large, and the influence of one pulse error can be made sufficiently small. However, if the measurement period is lengthened, the update interval of the instantaneous flow rate display becomes longer, and the responsiveness of the display to the flow rate change deteriorates.
Further, the measured instantaneous flow rate value is also the average flow rate value during the measurement period, and if the instantaneous flow rate within the measurement period is not constant, the instantaneous value cannot be represented accurately. Therefore, the measurement period for calculating the instantaneous flow rate cannot be lengthened unnecessarily. On the other hand, if the measurement period is the same, the flow rate becomes slower, and if the pulse frequency becomes slower, the number of pulses in the measurement period decreases, and the influence of one pulse error caused by the way of taking the measurement period becomes large. In particular, at a low flow rate, even if the flow rate is constant, the fluctuation range is large due to the difference in the number of measured pulses by one pulse, and when the instantaneous flow rate is displayed, the display value fluctuates greatly.

For example, as shown in FIG. 14, when the same pulse train is counted in the same period (T5 = T6), T5 is N counts, whereas T6 is N + 1 counts, and a difference of 1 count occurs. . If N is small, the difference of 1 count becomes a large measurement difference. That is, N =
If 10 then N + 1 = 11 and 11/10 = 1.1 times, and if N = 1 then N + 1 = 2 and 2/1 = 2 times, which is a big difference. An object of the present invention is to provide a highly accurate speed display device and water meter with low current consumption.

[0010]

In order to achieve the above object, the present invention provides a pulse generating means for generating a pulse proportional to the amount of movement of an object to be measured, and a power feeding means for intermittently supplying power to the pulse generating means. Reproducing means for reproducing the number of pulses generated when the pulse generating means is continuously supplied with electric power from the intermittent output of the pulse generating means, and generating means for generating a constant time for counting the number of pulses, Counting means for counting the number of pulses in a fixed time, first storage means for storing the count value of this counting means, and 1 when there is a difference of 1 pulse or more in the present count value from the previous count value The gist of the present invention is to include a calculating means for pulse-correcting to calculate a speed, a second storing means for storing a correction value by the calculating means, and a displaying means for displaying the speed calculated by the calculating means. .

[0011]

In such a configuration, the previous count value and the present count value are compared and corrected so as to reduce the fluctuation from the previous display value. Therefore, the constant speed is adjusted by the timing of counting pulses for a constant time. It is possible to prevent the point where the speed display fluctuates despite the fact that the measurement is displayed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram relating to a first embodiment of a speed display device of the present invention. In the figure, the sensor (1) that generates a pulse proportional to the amount of movement of the object to be measured is intermittently supplied with power by the sampling controller (2). As a result, the output state of the sensor, which is output intermittently, is reproduced by the pulse conversion unit (3) into pulses proportional to the amount of movement of the DUT, and the number of pulses for a fixed time specified by the interval timer (4) is counted. Counted in part (5). The count value before the counting unit (5) is updated is stored in the storage unit (6), and the arithmetic control unit (9) corrects the count value of the counting unit (5) and then uses the interval timer (4). The moving speed of the object to be measured, which is proportional to the average pulse speed in the designated constant time, is calculated, and the speed of the object to be measured is displayed on the display unit (8). The correction value corrected by the arithmetic control unit (9) is stored and stored in the correction value storage unit (7) and used for the next correction.

FIG. 2 is a timing chart for explaining the operation of the speed display device of FIG. In order to reduce current consumption, the sensor (1) is intermittently supplied with power by the sampling controller (2), and if the power is supplied, only when the pulse output indicated by the dotted line is supplied with power. It is output intermittently. The intermittent output obtained from the sensor (1) is reproduced by the pulse conversion unit (3) into a pulse proportional to the amount of movement of the measured object, but the pulse waveform is not faithfully reproduced. In order to know the speed of the object to be measured, it is necessary to know the number of pulses per unit time, and the number of pulses in a fixed time designated by the interval timer (4) is counted by the counting unit (5). It is ideal to know the instantaneous speed, but here the average speed for a fixed time specified by the interval timer (4) is obtained. Therefore, it is preferable that the fixed time specified by the interval timer (4) is short, but if the output pulse cycle of the sensor (1) corresponding to the minimum speed required for measurement is longer than 1 pulse, one pulse is not measured. In some cases, measurement becomes impossible. Therefore, it is determined in consideration of the fluctuation state of the measurement speed and the required followability. Similarly, the period of intermittent power supply by the sampling control unit (2) is also preferably set as long as possible in order to reduce the current consumption, but the output of the sensor (1) corresponding to the highest speed required for measurement. If it is not shorter than 1/2 of the pulse cycle, the on / off of the pulse cannot be detected and the number of pulses cannot be accurately measured. Therefore, it is determined by the measurement speed range and the required low current consumption.
Since these are not the essence of the present invention, detailed description will be omitted.

Generally, the application of the present invention is based on a demand for minimizing current consumption for battery operation and the like.
The sampling period is set to the maximum length, and therefore the output pulse period from the sensor (1) is also selected in consideration of the required response and accuracy.

The counting unit (5) counts the rising edges of the pulses obtained from the pulse conversion unit (3) at regular intervals designated by the interval timer (4), and the previous pulse in the counting unit (5) is counted. The count value is stored in the storage unit (6). The arithmetic control unit (9) uses the count value of the count unit (5), the previous count value stored in the storage unit (6), and the previous correction value stored in the correction value storage unit (7) to determine the counting unit ( After correcting the count value in 5) as shown below, calculate the corrected average speed for the fixed time specified by the interval timer (4) and display the speed of the DUT on the display (8). In addition, the correction value corrected this time is stored in the correction value storage unit (7).
Save in memory.

Here, it is assumed that the arithmetic control unit (9) performs the correction shown in FIG. When the velocity V is calculated from the corrected count value Y, if the movement amount per pulse is L, the unit time is M, and the measurement time is T,

[0017]

## EQU00002 ## V = L.times.Y.times.M / T. For example, L = 1 m / pulse, M = 1 second, T = 0.1
Second, assuming Y = 10 pulses,

[0018]

## EQU00003 ## V = 1 [m / pulse] × 10 [pulse] × 1 [second] /0.1 [second] = 100 [m / second]. However, since the arithmetic expression for calculating the velocity from the pulse count value is not the essence of the present invention, the description thereof will be omitted below, and only the correction of the count value will be described.

Further, in FIG. 2, since the count value of the counting unit (5) was 2 at the time of (a), the output of the counting unit (5) was 2, and it is stored in the storage unit (6). It is assumed that the previous count value is 2 and the previous correction value stored and stored in the correction value storage unit (7) is 0. Since the sum of the previous count value and the correction value, that is, the corrected count value used to calculate the display speed last time and the current count value match, no correction is made and the corrected count value is 2, the correction value is The speed becomes 0, and the speed is calculated from the corrected count value 2 and displayed on the display unit (8). This is the same as the previous display. Also, the correction value storage unit (7)
A correction value of 0 is stored and stored in.

Next, at the time of (b), since the count value of the counting unit (5) was 3, the output of the counting unit (5) was 3, and the previous count value stored in the storage unit (6) was 2. The previous correction value stored in the correction value storage unit (7) is 0. The sum of the previous count value and the correction value, that is, the corrected count value 2 used to calculate the previous display speed, and the current count value 3 is larger than 1 by one, the current count value is corrected by -1. The corrected count value is 2, and the correction value is -1, and the speed is calculated from the corrected count value 2 and displayed on the display unit (8). This is the same as the previous display. -1 is stored as the correction value.

Furthermore, since the count value of the counting unit (5) was 1 at the time of (c), the output of the counting unit (5) was 1, and the previous count value stored in the storage unit (6) was 3, The previous correction value stored in the correction value storage unit (7) is -1.
The sum of the previous count value and the correction value, that is, the corrected count value used to calculate the previous display speed is 2, and the current count value 1
Is smaller by 1 or more, the current count value is corrected by +1 and the corrected count value is 2 and the correction value is +1.
The speed is calculated by and displayed on the display unit (8). This is the same as the previous display.

As described above, in the speed display device of this embodiment, the current consumption is reduced by intermittently activating the sensor (1). Therefore, when the speed is calculated by the number of pulses for a certain period of time. By simply making a simple correction to the count value, it is possible to prevent the displayed value from changing even if there is no speed change depending on how the fixed time is taken. For example, 3
When counting Hz pulses at 0.5 second intervals, one pulse and two pulses are alternately counted. Since it is unavoidable that an error of 1 pulse occurs, in order to obtain the required accuracy, the measurement period should be lengthened to increase the total number of measurement pulses and reduce the effect of 1 pulse. Although it is possible, it is obviously not preferable that the displayed value fluctuates when measuring at a constant speed. According to the present embodiment, when the speed decreases, the corrected count value is displayed at a speed corresponding to 2, and when the speed increases, the corrected count value is displayed at a constant speed corresponding to 1. Can be

Further, in the second embodiment of the present invention, the arithmetic control unit (9) is configured to perform the correction shown in FIG. That is, the current count value is more than the previous corrected count value.
If it is larger than 0.5 (the count value may not be an integer because the correction is 0.5 units), make a correction of -0.5,
-0.5 is stored in the correction value. If the count value this time is smaller than the count value after correction by 0.5 or more, +0.5 is corrected and +0.5 is stored in the correction value.

By carrying out this correction, the correction on the + side and the correction on the-side are averaged, and the bias of the correction is eliminated. For example, 3Hz
When the pulses of are counted at 0.5 second intervals, one pulse and two pulses are counted alternately. According to the present embodiment, it is possible to display a constant value at the speed corresponding to the corrected count value of 1.5 regardless of whether the speed is decreasing or the speed is increasing.

Next, in the third embodiment of the present invention, the arithmetic control unit (9) is configured to perform the correction shown in FIG. In the present embodiment, the same correction as in the first embodiment is performed only when the previous correction value was 0. According to this embodiment, since the correction is not continuously performed,
When the speed continuously increases or decreases, no correction is performed, and one pulse generated by increasing or decreasing the pulse counting period when the constant speed continues (for example,
(There is no difference on the + side or − side continuously so that 2 pulses and 3 pulses are alternately counted).

Next, in the fourth embodiment of the present invention, the arithmetic control unit (9) is configured to perform the correction shown in FIG. In this embodiment, the same correction as in the second embodiment is performed only when the previous correction value is 0. According to this embodiment, even when the speed is decreasing,
Even when the speed increases, if the speed becomes constant, the corrected count value can be displayed constant.

Next, FIG. 7 shows a functional block diagram of a water supply meter having an instantaneous flow rate display function. In the figure, when water flows through the water meter, the impeller (10) rotates in proportion to the amount of water, and a magnet (11) attached to the impeller (10) creates a rotating magnetic field in synchronization with the rotation. . The rotation sensor (12) detects the rotating magnetic field of the magnet (11) and generates a pulse proportional to the rotation speed, and the CPU (15) controls the I / O (14) to intermittently rotate the rotation sensor (12). Is supplied to the rotation sensor (12), and intermittently sampled pulses from the rotation sensor (12)
It is read by the CPU (15) via the O (14), reproduced into a pulse proportional to the rotation speed, and the pulse count is integrated and recorded. The cumulatively recorded number of pulses is converted into an integrated flow rate value by multiplying the preset number of pulses by the conversion coefficient of the flow rate value, and is displayed on the display unit (8). The changeover switch (13) switches the display from the integrated value display to the instantaneous flow rate display. When the CPU (15) detects that the changeover switch (13) has been operated, the CPU (15) causes the interval timer (4) to change. The number of pulses for a certain period designated by) is counted, and the instantaneous flow rate (flow rate) is calculated by the same method as in the first embodiment and displayed on the display unit (8). It is also clear that the pulse integration must be continued,
The pulses measured during the display of the instantaneous flow rate shall be cumulatively recorded.

The CPU (15) for performing these series of operations is
Various data and the like are recorded and stored in the RAM (17) according to the program written in the ROM (16), but since these items are basic items for using the microcomputer, detailed description thereof will be omitted. Further, it is difficult to externally supply power to the water meter, and all power is supplied by a built-in battery (not shown). Therefore, lowering the current consumption is an important matter for extending the life of the battery, and in addition to the low power consumption due to the intermittent power supply of the rotation sensor, the power consumption can be reduced in each part.

As described above, in this embodiment, when the current consumption is reduced by intermittently activating the sensor (1), it is necessary to calculate the instantaneous flow rate from the number of pulses for a certain period of time. Therefore, it is possible to prevent the display value from changing even if the flow rate does not change depending on how to take a certain period of time, by simply correcting the count value. Furthermore, except for the change-over switch (13), it is common with the circuits required for the original integrated flow rate value display, and the instantaneous display function can be added without adding a special circuit for the instantaneous flow rate display. -Supply water meter with an instantaneous flow rate function that is excellent in performance. In addition, the pulse count for integrating the flow rate and the pulse count for calculating the instantaneous flow rate are shared, and the processing time for displaying the instantaneous flow rate and the circuit operation are minimized to reduce the current consumption. Easy to do. It should be noted that the above-described second to fourth embodiments can be applied to the water supply meter of this embodiment, and the same effect can be obtained.

[0030]

As described above, according to the present invention, the pulse generating means for generating a pulse proportional to the moving amount of the object to be measured, the power feeding means for intermittently supplying power to the pulse generating means, and the pulse generating means are provided. Reproducing means for reproducing the number of pulses generated when the pulse generating means is continuously supplied with power from the intermittent output, generating means for generating a constant time for counting the pulse number, and counting the number of pulses for the constant time The counting means, the first storage means for storing the count value of the counting means, and the calculating means for correcting the current value by one pulse when there is a difference of one pulse or more from the previous count value and calculating the speed. Since the second storage means for storing the correction value by the calculation means and the display means for displaying the speed calculated by the calculation means are provided, the speed display device and the water meter with low current consumption and high accuracy are provided. Can get

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a speed display device of the present invention.

FIG. 2 is a diagram for explaining the operation of the speed display device of FIG.

FIG. 3 is a diagram for explaining a first count value correction method of the speed display device of FIG. 1;

FIG. 4 is a diagram for explaining a second count value correction method of the speed display device of FIG. 1;

FIG. 5 is a diagram for explaining a third count value correction method of the speed display device of FIG. 1;

FIG. 6 is a diagram for explaining a fourth count value correction method of the speed display device of FIG. 1;

FIG. 7 is a configuration diagram showing an embodiment of a water supply meter of the present invention.

FIG. 8 is a block diagram of a conventional water supply meter.

FIG. 9 is a diagram for explaining the operation of the water supply meter shown in FIG. 8;

FIG. 10 is a diagram for explaining the operation of the water meter in FIG.

FIG. 11 is a block diagram of the rotation sensor 12 of the water meter in FIG.

FIG. 12 is a diagram for explaining the relationship between the magnetic field applied to the rotation sensor 12 of the water meter of FIG. 8 and the output.

FIG. 13 is a view for explaining the operation of the water supply meter shown in FIG.

FIG. 14 is a diagram for explaining the operation of the water supply meter shown in FIG. 8;

[Explanation of symbols]

1 ... Sensor, 2 ... Sampling control unit, 3 ... Pulse conversion unit, 4 ... Interval timer, 5 ... Counting unit, 7 ... Correction value storage unit, 9 ... Calculation control unit, 12 ... Rotation sensor, 13 ... Changeover switch, 15 ... CPU

Claims (8)

[Claims] 1. A pulse generating means for generating a pulse proportional to the amount of movement of an object to be measured, a power feeding means for intermittently feeding power to the pulse generating means, and an intermittent output of the pulse generating means from the pulse generating means. Reproducing means for reproducing the number of pulses generated when the power is continuously supplied, generating means for generating a constant time for counting the number of pulses, counting means for counting the number of pulses for the constant time, and this counting A first storage means for storing the count value of the means; a calculating means for correcting the current count value by one pulse when there is a difference of one pulse or more from the previous count value; A speed display device having a second storage means for storing the correction value by the display means and a display means for displaying the speed calculated by the calculation means. 2. The speed display according to claim 1, wherein, in the correction of the count value, if the difference between the count value after the previous correction and the count value this time is 0.5 pulse or more, 0.5 pulse correction is performed. apparatus. 3. The correction of the count value is performed by correcting one pulse only when the previous correction value is 0 or when the current count value is more than one pulse different from the previous correction count value. Item 2. The speed display device according to item 1. 4. The correction of the count value is performed by 0.5 pulse correction only when the previous correction value is 0 or the difference between the previous correction value and the present count value is 0.5 pulse or more. Item 2. The speed display device according to item 1. 5. Rotating means for rotating in proportion to the amount of water, pulse generating means for generating a pulse proportional to the rotation of the rotating means, power feeding means for intermittently feeding power to the pulse generating means, and the pulse generating means. Reproducing means for reproducing the number of pulses generated when the pulse generating means is continuously supplied with electric power from the intermittent output of the means, converting means for integrating and recording the pulses, and converting to an integrated flow rate value, and this converting means. Display means for displaying the integrated flow rate value, generation means for generating a fixed time for counting the number of pulses, input means for inputting a command to switch the display from the outside, and the constant value when a command is input to this input means. Counting means for counting the number of pulses in time, and this count value is 1 more than the previous count value.
When there is a difference of more than a pulse, one pulse is corrected to calculate the instantaneous flow rate, and the calculating means for changing the integrated value display to display the instantaneous flow rate, and the storage means for storing the correction value by this calculating means Meta. 6. The water supply system according to claim 5, wherein in the correction of the count value, if the current count value has a difference of 0.5 pulses or more from the count value after the previous correction, 0.5 pulse correction is performed. -Ta. 7. The count value correction is performed by correcting one pulse only when the previous correction value is 0 or when the current count value is more than one pulse different from the previous correction count value. Item 5. The water supply meter according to item 5. 8. The correction of the count value is carried out by 0.5 pulse correction only when the previous correction value is 0 or the difference between the previous correction value and the present correction value is 0.5 pulse or more. Item 5. The water supply meter according to item 5.