JP3355310B2 - Tension measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tension measuring device for measuring the tension of a belt such as a belt supported between two points.

[0002]

2. Description of the Related Art In general, belts such as belts stretched on rotating supports such as pulleys and rollers on a driving side and a driven side are used for transmitting driving force from a driving side to a driven side. It is used for placing and transporting a conveyed object.
At this time, if the tension of the band is excessive, the band is worn out early and the life is shortened. On the other hand, if the tension of the band is too small, the band is moved in the longitudinal direction and the width direction with respect to the rotating support. And the driving force (rotational force) of the rotating support cannot be transmitted efficiently. Therefore, at the time of stretching or inspection of the band, it is necessary to inspect whether or not the band is stretched within a predetermined tension range.
2. Description of the Related Art A tension measuring device of a type that measures tension based on a natural frequency when a band vibrates is widely used.

Since it is necessary for the above-described tension measuring device to accurately obtain a natural frequency in order to realize a highly accurate measurement of tension, various configurations for accurately obtaining a natural frequency have been proposed. ing. For example, Japanese Patent Publication No. 7-11459
In the publication, transducers are respectively installed on the front side and the back side of the belt, which is a belt-shaped body, and after detecting the vibration of the belt with a phase shifted by 180 °, the noise component is removed by combining the two vibrations. A configuration for amplifying a vibration component while the vibration component has been proposed. According to this configuration, the waveform of the natural frequency has a large amplitude and the extraction is simplified, so that the natural frequency can be easily obtained.

[0004]

However, in a configuration in which the vibration component is amplified to increase the waveform of the natural frequency to a large amplitude as in the above-described conventional technique, when the tension is measured with high accuracy, There is a problem that it often takes a long time to obtain a measurement result.

That is, when the belt is vibrated by applying an impact, the belt vibrates in an irregular waveform including a harmonic component and an impact component immediately after the vibration is started, and the belt vibrates with time. As a result, harmonic components and the like are attenuated and gradually oscillate with a sinusoidal waveform of the natural frequency of the belt (FIG. 6A).
(B)). Therefore, in the conventional configuration, the waiting time until the irregular waveform is attenuated is set experimentally or empirically in order to extract the irregular waveform and not obtain an incorrect natural frequency. After the elapse of the standby time, it is necessary to perform processing for obtaining a natural frequency. However, in this case, the standby time tends to be set to be excessively long so as to surely attenuate the irregular waveform, so that it often takes a long time to obtain a tension measurement result.

In view of the above, Japanese Patent Publication No. 63825/1994 focuses on the difference between the above-mentioned irregular waveform immediately after the vibration and the regular waveform of the natural frequency, and determines the wavelength of the vibration waveform for each period. A configuration has been proposed in which this frequency is used as a natural frequency when the frequency is continuous within a predetermined fluctuation range. According to this configuration, the standby time can be significantly reduced as compared with the case where the standby time is fixedly set in advance. However, in this case, the vibration waveform may have substantially the same frequency (period) depending on the shape of the irregular waveform immediately after the vibration, and thus the reliability is insufficient due to erroneous detection of the natural frequency in this case. There is a problem that is.

[0007] Accordingly, the present invention provides a tension measuring device capable of measuring tension in a short time with sufficiently high reliability.

[0008]

In order to solve the above-mentioned problems, a first aspect of the present invention is to obtain a natural frequency from a vibration when a belt-like body supported between two points is vibrated, and obtain the natural frequency. In a tension measuring device for measuring a tension based on a number, a vibration detecting means for detecting a vibration of the band-like body and outputting a waveform signal, and a rising period and a falling period of the waveform signal, A cycle detecting means which is obtained alternately for every half cycle; and, when a variation width of the rising cycle and the falling cycle obtained alternately is continuous within a predetermined range, an average value of these successively obtained cycles. And a natural frequency detecting means for obtaining the natural frequency as a natural frequency.

According to the above arrangement, the natural frequency is obtained based on the rising cycle and the falling cycle obtained alternately of the waveform signal obtained by detecting the vibration of the belt-like body, so that the standby time is fixedly set in advance. In this case, the waiting time for obtaining the natural frequency can be significantly reduced as compared with the case where the tension is obtained, and as a result, the tension can be measured in a short time.

Further, when the band vibrates in an irregular waveform including a harmonic component and an impact component, the vibration waveform may have substantially the same frequency (period) depending on the form of the irregular waveform.
However, according to the above configuration, the rising cycle and the falling cycle are obtained alternately every half cycle, and the natural frequency is obtained based on the fluctuation width of these alternately obtained cycles. Therefore, the natural frequency and the tension can be obtained with higher reliability than when the natural frequency is obtained based on the fluctuation width of the waveform signal for each cycle.

According to a second aspect of the present invention, in the tension measuring device according to the first aspect, the natural frequency detecting means is provided when the fluctuation width between the rising period and the falling period falls within a predetermined range. A cycle addition means for calculating the total value of these cycles, a counting means for counting the number of times the variation width is continuous within a predetermined range to obtain the number of matches, and dividing the total value by the number of matches to obtain an average value. Means for calculating an average value, and determining whether the number of matches is equal to or greater than a first threshold value,
The first means is that only the total value is calculated by the period adding means until the average value is equal to or more than the first threshold value, and the average value is calculated by the average value calculating means when the average value is equal to or more than the first threshold value. And determining means.

According to the above arrangement, the average value is not calculated by the average value calculating means until the average value becomes equal to or larger than the first threshold value, so that the rising period coincides with the falling period accidentally. Since unnecessary calculation processing in such a case can be prevented, the processing capacity of the tension measuring device can be increased as a result.

According to a third aspect of the present invention, in the tension measuring device according to the second aspect, the natural frequency detecting means further comprises:
It is determined whether or not the number of matches is equal to or greater than a second threshold. Until the number of matches is equal to or greater than the second threshold, calculation of the average value by the average value calculator is continued. In this case, there is provided a second judging means for setting the average value to a natural frequency when it becomes true.

According to the above configuration, when the fluctuation range within the predetermined range is equal to or greater than the second threshold value, the average value of these periods is used as the natural frequency. The frequency and tension can be determined.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 1, a tension measuring device according to the present embodiment
And the signal processing unit 20 connected to the transducer 4
A data processing unit 11 connected to the signal processing unit 20;
An operation unit (not shown) including various switches and a tension T
And a display device 19 such as an LCD device for displaying the same.

The transducer 4 is fixedly mounted on a housing (not shown) or movably via a signal cable, and includes a driving pulley 1 and a driven pulley 2.
When placed opposite to the surface of the belt 3 stretched between the two points, the sound wave generated by the vibration of the belt 3 is converted into an electric waveform signal a and output.

The transducer 4 is connected to the filter circuit 5 of the signal processing section 20. The filter circuit 5 is configured to remove a noise component included in the vibration signal a. The filter circuit 5 is connected to a comparator circuit 6 for shaping the waveform of the vibration signal a and outputting a comparator signal b having a rectangular waveform. The comparator circuit 6 detects a rising portion and a falling portion of the comparator signal b. And is connected to an edge detection circuit 7 including a differentiating circuit for outputting an edge signal c.

The edge detection circuit 7 is connected to the delay circuit 8, the latch circuit 9, and the data processing unit 11.
The delay circuit 8 is configured to output the delay signal d to the counter circuit 10 after a lapse of the delay time Ta from the input of the edge signal c. The counter circuit 10 is configured to increment the count value in the input cycle of the clock signal CLK (for example, 0.01 ms) and to clear the count value to zero every time the delay signal d is input.
The counter circuit 10 is connected to the latch circuit 9, and the latch circuit 9 takes in the count signal e (count value) from the counter circuit 10 at the input timing of the edge signal c from the edge detection circuit 7 described above. And holds the latched signal f, and releases the held state at the input timing of the processing completion signal g from the data processing unit 11.

The data processing section 11 includes an I / O section 12 connected to an operation section such as the latch circuit 9 and the edge detection circuit 7 and a measurement start switch (not shown), and various controls such as a tension calculation routine. Storage unit 13 storing a program
An operation unit 14 for executing a control program; a printer IF unit 15 connectable to a printer device 18; a display IF unit 16 connected to a display device 19;
And a signal bus 17 for interconnecting 2-16. Then, the data processing unit 11 executes the tension calculation routine of FIG. 3 in the calculation unit 14 to obtain a natural frequency F by an operation described later, and this natural frequency F
Is calculated based on the calculated tension T and output to the printer device 18 and the display device 19.

In the above configuration, the operation of the tension measuring device will be described. By performing an operation such as turning on the power supply of the tension measuring device, the arithmetic unit 14 performs the operation shown in FIG.
When the tension calculation routine is executed, the display device 1 first informs the operator to input an initial value.
9 is displayed on the screen 9 so that input of an initial value can be accepted (S1). Thereafter, when the operator inputs initial values such as the belt linear density A and the inter-axis distance L of the belt 3 to be measured, the initial values are stored in the storage unit 13, and the natural frequency determination process is performed. Perform (S2).

That is, as shown in FIG. 4, after initial setting of various parameters (rise cycle Ti, fall cycle Ti ', etc.) (S11), it is confirmed that the operator applied a shock to the belt 3 and caused it to vibrate. For detection, an input of a measurement start command from a measurement start switch (not shown) is received (S12). After that, by inputting the measurement start command,
When the operator determines that the belt 3 has been vibrated, I /
The input state in the O section 12 is monitored.

At this time, in the signal processing unit 20 located on the upstream side of the I / O unit 12, the belt 3 is operated by an operator.
Is operated as follows by being excited. First, a sound wave generated by the vibration of the belt 3 is received by the transducer 4 and converted into an electrical waveform signal a by the transducer 4 (FIG. 2A). Then, after the noise component is removed from the waveform signal a by the filter circuit 5, the comparator circuit 6 compares the waveform signal a with a predetermined threshold value. A rectangular comparator signal b
(FIG. 2B). Thereafter, the comparator signal b is input to the edge detection circuit 7, and the rising and falling portions are detected and converted into a single-pulse edge signal c (FIG. 2 (c)).

The edge signal c is output to the delay circuit 8, the latch circuit 9, and the I / O unit 12, respectively. The delay circuit 8 outputs the delay signal d to the counter circuit 10 after the elapse of the delay time Ta from the input time of the edge signal c (FIG. 2 (d)).
Clear the count value to zero. The counter circuit 10 outputs the count value as a count signal e while incrementing the count value from "0" in the cycle of the clock signal CLK each time the delay signal d is cleared to zero (FIG. 2 (e)). On the other hand, the latch circuit 9 captures and holds the count signal e (count value) from the counter circuit 10 every time the edge signal c is input, and stores the count value as the latch signal f in the I / O unit 12. Output (FIG. 2 (f)).

By such an operation, the edge signal c is changed to I /
When the input to the O section 12 is detected, the I / O section 12
Then, the count value (for example, t1) of the latch signal f is fetched via, and this count value is substituted for the first pulse width t1 (S13). Thereafter, at the input timing of the next edge signal c, the count value (for example, t2) of the latch signal f is fetched via the I / O unit 12, and this count value is substituted for the second pulse width t2 (S14).

Next, the first pulse width t1 and the second pulse width t
2 and the rising period Ti (= t1
+ T2), and the period Ti is corrected by the delay time Ta to obtain a calculated value Tw (S15). Then, a natural frequency determination process described later is executed so as to obtain the natural frequency F using the calculated value Tw (S16). After this,
By checking the state of the completion flag K, it is determined whether or not the natural frequency F has been obtained by the natural frequency determination processing (S17). If the natural frequency F has been obtained (S1).
7, YES), terminates this routine, and returns to the tension calculation routine which is the main routine.

On the other hand, if the natural frequency F cannot be obtained (S17, NO), the count value of the second pulse width t2 is replaced with the first pulse width t1 (S18), and the next edge signal c is input. At a timing, the count value (for example, t3) of the latch signal f is fetched via the I / O unit 12, and this count value is substituted for the second pulse width t2 (S19). Then, the falling period Ti ′ (= t1 + t2) is calculated by adding the first pulse width t1 and the second pulse width t2, and the calculated value Tw is calculated by correcting the period Ti ′ by the delay time Ta. After the calculation (S20), a natural frequency determination process described later is executed so as to obtain the natural frequency F using the calculated value Tw (S16). Thereafter, by checking the state of the completion flag K, it is determined whether or not the natural frequency F has been obtained by the natural frequency determination processing (S22).
If the natural frequency F is obtained (S22, YES),
This routine is terminated and the routine returns to the tension calculation routine.

On the other hand, when the natural frequency F is not obtained (S22, NO), the count value of the second pulse width t2 is replaced with the first pulse width t1 (S23), and the cycle count value i is set to "1". "After moving up (S24), the process is repeated from S14.

Thus, by repeatedly executing S14 to S24, for example, as shown in FIGS. 6A and 6B, when the waveform signal a is continuously generated by the vibration of the belt 3, , The rising period Ti (t1
+ T2, t3 + t4,...) And the falling period T
i ′ (t2 + t3, t4 + t5,...) are alternately obtained for each half wavelength (half cycle) of the waveform signal a, and the natural frequency determination processing (S16. S21) will be executed.

Next, the natural frequency determination processing (S16 / S2)
Regarding the operation of 1), the waveform signal a shown in FIGS.
This will be described in detail with reference to FIGS. 7 and 8 and the explanatory diagrams of the pulse width of the waveform signal a in FIG. 7 and FIG.

FIGS. 7 and 8 are explanatory diagrams of FIG.
(A) and (b) the initial vibration of the waveform signal a (T1 · T
It shows a process of data processing of a series of vibration states from 1 ′) to a stable state (T39 · T39 ′). Specifically, each pulse at the time of execution of the above-described natural frequency determination routine is shown. The rising period Ti and the falling period Ti 'with respect to the width, the number of matches C between these two periods Ti.Ti', the total value Tg of the periods Ti.Ti 'when both periods Ti.Ti' match, and the total value Tg Is divided by the number of coincidences C with the cycle average value Th.

When the rise period Ti and the fall period Ti 'are obtained as described above, the natural frequency determination routine shown in FIG. 5 is executed to perform the natural frequency determination process (S16 and S21).

First, as shown in FIG. 5, a new total value Tg is calculated by adding the calculated value Tw obtained in S15 or S20 of FIG. 4 to the total value Tg (S3).
1). Thereafter, the rising period Ti and the falling period T
It is determined whether or not the absolute value of the difference from i ′ is equal to or less than a time threshold Ts such as 50 ms (S32). If not less than the time threshold value Ts (S32, NO), the fluctuation width between the two periods Ti and Ti 'is large, so that the belt 3 vibrates in an irregular waveform including a harmonic component and an impact component. It is determined that there is, and the number of matches C is set to “1” and the total value Tg is set to “0” (S33). After the completion flag K is set to "0" (S34), the process returns to the natural vibration determination routine so as to capture the calculated value Tw of the next rising period Ti or falling period Ti '.

Thus, as shown in FIG. 7, for example, in a period (T1 to T7) in which the cycle count value i is 1 to 7,
Since the fluctuation width between the rising period Ti and the falling period Ti 'is large, the number of matches C becomes 1 and the total value Tg becomes one of the rising period Ti and the falling period Ti'. Become.

On the other hand, if the time is equal to or less than the time threshold value Ts (S32, YES), it is determined that the vibration is stable because the two periods Ti and Ti 'substantially coincide with each other. Is added (S11). Thereafter, in order to confirm that the stable state of vibration continues, it is determined whether or not the number of matches C is equal to or more than a first threshold value C1 such as five (S36), and the first threshold value is determined. If not more than the value C1 (S3
6, NO), and after setting the completion flag K to “0” (S3
4), next rising period Ti or falling period T
The process returns to the natural vibration determination routine so as to capture the calculated value Tw of i ′.

As a result, as shown in FIG. 7, the number of matches C becomes "2" between the matched cycles T7 and T7 ', for example, during a period (T7 to T8) in which the cycle count value i is 7 to 8. "And the values of both cycles T7 and T7 '(1.7
Value (3.44 ms) obtained by adding 2 ms / 1.72 ms)
Becomes the total value Tg. Then, during the next cycle T7 ′ · T8, the fluctuation width is equal to or greater than the time threshold value Ts, so that the above-described S33 is executed, whereby the number of matches C becomes “1” and the total value Tg becomes It is set to “0” and returns to the original state. Also, as shown in FIG.
In the period (T19 to T21) in which the cycle count value i is 19 to 21 (T19 to T21), the sequentially input periods Ti · Ti ′ substantially coincide with each other. The sum is obtained as a total value Tg.

Thereafter, as shown in FIG. 5, when the number of coincidences C becomes equal to or more than the first threshold value C1 (S36, YE
S), it is determined that the stable state of vibration is continuing, and the total value Tg is divided by the number of coincidences C to obtain the periodic average value Th.
Is obtained (S37). Thereafter, in order to increase the accuracy of the natural frequency F, the number of matches C is set to a second threshold C such as 43, for example.
It is determined whether or not the number has reached 2 or more (S38). If it is not equal to or greater than the third threshold value C2 (S38, NO), the completion flag K is set to "0" (S34), and the process returns to the natural vibration determination routine, and further includes the next cycle Ti.Ti '. A period average value Th is obtained. If the number of matches C is equal to or greater than the second threshold value C2 (S38, YES),
The cycle average value Th is set as the natural frequency F (S3
9) After setting "1" to the completion flag K (S40),
The process returns to the natural vibration determination routine.

As described above, the completion flag K is set to "1".
Is returned to the natural vibration determination routine with
Then, in S17 or S22 in FIG.
It is determined that the number F has been obtained (S17, YES or S22, Y
ES), and returns to the tension calculation routine of FIG. Soshi
Then, the natural frequency F is calculated by the formula of the tension T (T = 4L^TwoAF ^Two
/9.8), and further input into this formula at S1.
The belt linear density A and the center distance L
Therefore, the tension T is calculated (S3). Thereafter, the tension T is increased.
When output to the display device 19 in FIG. 1 to notify the operator,
Both are printed out to the printer device 18 as necessary.
(S4).

As described above, the tension measuring device according to the present embodiment uses the natural frequency F from the vibration when the belt 3 (band) supported between the two points of the driving pulley 1 and the driven pulley 2 is excited. And a tension is measured based on the natural frequency F. The transducer 4 detects vibration of the belt 3 and outputs a waveform signal a (vibration detecting means).
Frequency detecting means (signal processing unit 20, natural frequency determination routine) for alternately obtaining a rising period Ti and a falling period Ti 'of the waveform signal a for each half period of the waveform signal a; A natural frequency detecting means (natural frequency determining routine) for obtaining an average value of the continuous periods as a natural frequency F when a fluctuation width from the falling period Ti 'is continuous within a predetermined range. Has been.

In this embodiment, the case where the tension of the belt 3 is measured has been described. However, the present invention is not limited to this, and the tension of all the strips supported between two points is measured. can do. Examples of the band include a metal band plate and a synthetic resin film member.

According to the above configuration, the standby frequency is fixedly set in advance in order to obtain the natural frequency F based on the rising period Ti and the falling period Ti 'of the waveform signal a in which the vibration of the belt 3 is detected. Natural frequency F
Can be greatly reduced, and as a result, the tension can be measured in a short time. Further, when the belt 3 is vibrating with an irregular waveform including a harmonic component and an impact component, the vibration waveform may have substantially the same frequency (period) depending on the form of the irregular waveform. According to the above configuration, the rising period Ti
And the falling period Ti ′ are obtained alternately every half period,
Since the natural frequency F is obtained based on the fluctuation width of these periods, the natural frequency F is obtained with higher reliability than when the natural frequency F is obtained based on the fluctuation width of the waveform signal a for each period. And tension can be obtained.

The above-mentioned natural frequency detecting means (natural frequency determining routine) is adapted to detect when the fluctuation range between the rising period Ti and the falling period Ti 'falls within a predetermined range.
Period adding means for calculating the total value Tg of these periods (FIG. 5)
And S31), and counting means for counting the number of times the fluctuation width continues within a predetermined range to obtain the number of matches C (S35 in FIG. 5).
And the total value Tg divided by the number of matches C to calculate the cycle average value Th
Average value calculating means (S37 in FIG. 5) for determining the number of times of matching and whether or not the number of matches C has become equal to or greater than a first threshold value C1;
Until it becomes equal to or more than the first threshold value, only the total value Tg is calculated by the cycle addition means, and when it becomes equal to or more than the first threshold value C1, the average value calculation means calculates the cycle average value Th. The configuration includes a first determination unit (S36 in FIG. 5).

According to the above configuration, the average value is not calculated by the average value calculation means until the average value reaches the first threshold value C1.
It is possible to prevent a useless calculation process when the falling period Ti 'coincides with the falling period Ti' by chance, and as a result, the processing capability of the tension measuring device can be increased.

Further, the natural frequency detecting means determines whether or not the number of coincidences C is equal to or more than the second threshold value C2. The calculation of the average value is continued, and a second determination means (S38 in FIG. 5) is used which sets the periodic average value Th to the natural frequency F when the average value becomes equal to or more than the second threshold value C2.

According to the above configuration, the rising period Ti
When the state in which the fluctuation width between the falling period Ti ′ and the falling period Ti ′ is within the predetermined range continues for the second threshold value C2 or more, the period average value Th is set to the natural frequency F, so The frequency F and the tension can be determined.

In the present embodiment, it is detected that the operator has applied an impact to the belt 3 and caused it to vibrate in accordance with a measurement start command from the measurement start switch. However, the present invention is not limited to this. That is, the waveform signal a from the filter circuit 1 in FIG. 1 is converted into a digital value waveform level signal by an A / D converter, and a measurement start command is output when the waveform level signal exceeds a predetermined value. It may be configured. In this case, it is possible to automatically detect that the belt 3 is shocked and vibrated by the operator. Further, it may be possible to switch between such automatic detection and manual detection by the measurement start switch.

Further, in the present embodiment, the configuration is provided with one comparator circuit 6; however, the present invention is not limited to this, and two comparators having different hysteresis widths are provided.
A configuration may be adopted in which a plurality of comparator circuits are connected in parallel, and the natural frequency F is obtained using comparator signals output from these circuits.

[0047]

According to a first aspect of the present invention, there is provided a tension measuring device for obtaining a natural frequency from vibration when a belt-like body supported between two points is vibrated, and measuring a tension based on the natural frequency. A vibration detecting means for detecting a vibration of the band-shaped body and outputting a waveform signal; a cycle detecting means for alternately obtaining a rising cycle and a falling cycle of the waveform signal for each half cycle of the waveform signal; A natural frequency detecting means for obtaining, when the variation width of the rising cycle and the falling cycle obtained alternately within a predetermined range continues within a predetermined range, an average value of these successively obtained alternating cycles as a natural frequency; It is a configuration provided with.

According to the above arrangement, the natural frequency is obtained based on the rising cycle and the falling cycle obtained alternately of the waveform signal obtained by detecting the vibration of the belt-like body, so that the standby time is fixedly set in advance. In this case, the waiting time for obtaining the natural frequency can be significantly reduced as compared with the case where the tension is obtained, and as a result, the tension can be measured in a short time. further,
The rising cycle and the falling cycle are obtained alternately every half cycle, and the natural frequency is obtained based on the fluctuation width of these cycles obtained alternately. Therefore, based on the fluctuation width of each waveform signal in each cycle. Thus, the natural frequency and the tension can be obtained with higher reliability than when the natural frequency is obtained.

According to a second aspect of the present invention, there is provided the tension measuring device according to the first aspect, wherein the natural frequency detecting means is provided when the fluctuation width between the rising period and the falling period falls within a predetermined range. A cycle addition means for calculating the total value of these cycles, a counting means for counting the number of times the variation width is continuous within a predetermined range to obtain the number of matches, and dividing the total value by the number of matches to obtain an average value. Means for calculating an average value, and determining whether the number of matches is equal to or greater than a first threshold value,
The first means is that only the total value is calculated by the period adding means until the average value is equal to or more than the first threshold value, and the average value is calculated by the average value calculating means when the average value is equal to or more than the first threshold value. And a determination unit.

According to the above configuration, the average value is not calculated by the average value calculation means until the average value becomes equal to or greater than the first threshold value. In such a case, useless calculation processing can be prevented, and as a result, the processing capability of the tension measuring device can be increased.

According to a third aspect of the present invention, in the tension measuring device according to the second aspect, the natural frequency detecting means further comprises:
It is determined whether or not the number of matches is equal to or greater than a second threshold. Until the number of matches is equal to or greater than the second threshold, calculation of the average value by the average value calculator is continued. And a second determination unit that sets the average value to a natural frequency when the average value becomes true.

According to the above configuration, when the range of fluctuation within the predetermined range is equal to or greater than the second threshold value, the average value of these periods is used as the natural frequency. There is an effect that the frequency and the tension can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of a tension measuring device.

FIG. 2 is a timing chart of signals in the block diagram of FIG. 1;

FIG. 3 is a flowchart of a tension calculation routine.

FIG. 4 is a flowchart of a natural frequency determination routine.

FIG. 5 is a flowchart of a natural frequency determination routine.

FIGS. 6A and 6B are explanatory diagrams showing states of waveform signals, wherein FIG. 6A shows a state from immediately after vibration until a predetermined time has elapsed, and FIG. 6B shows a state after the predetermined time has elapsed.

FIG. 7 is an explanatory diagram showing a process of performing data processing on the waveform signal of FIG. 6;

FIG. 8 is an explanatory diagram showing a process of performing data processing on the waveform signal of FIG. 6;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 drive pulley 2 driven pulley 3 belt 4 transducer 5 filter circuit 6 comparator circuit 7 edge detection circuit 8 delay circuit 9 latch circuit 10 counter circuit 11 data processing unit 12 I / O unit 13 storage unit 14 arithmetic unit 15 printer IF unit 16 Display IF unit 17 Signal bus 18 Printer device 19 Display device 20 Signal processing unit

Continued on the front page (72) Inventor: Manabu Tanabe 4-1-1-21, Hamazoe-dori, Nagata-ku, Kobe-shi, Hyogo Prefecture Inside Mitsuboshi Belting Co., Ltd. Co., Ltd. (72) Inventor Hideaki Seki 1127, Ishigaya, Shoin-sha, Okubo-cho, Akashi City, Hyogo Prefecture (56) References JP-A-6-281517 (JP, A) JP-A-5-133967 ( JP, A) JP-A-8-177871 (JP, A) JP-A-8-193876 (JP, A) JP-A-6-265399 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , (DB name) G01L 5/10 G01H 13/00

Claims (3)

(57) [Claims] 1. A tension measuring device for obtaining a natural frequency from vibration when a band supported between two points is excited and measuring a tension based on the natural frequency, wherein the vibration of the band is Vibration detection means for detecting the waveform signal and outputting a waveform signal, the rising cycle and the falling cycle of the waveform signal,
A period detecting means for obtaining alternately for each half cycle of the waveform signal, when the variation range of the rising period and falling period obtained alternately continuous in a predetermined range, determined alternately to these successive A natural frequency detecting means for obtaining an average value of a cycle as a natural frequency. 2. The natural frequency detecting means includes: cycle adding means for calculating a total value of the rising cycle and the falling cycle when the changing range between the rising cycle and the falling cycle falls within a predetermined range; Counting means for counting the number of consecutive times within a predetermined range to obtain the number of matches; average value calculating means for dividing the total value by the number of matches to calculate an average value; It is determined whether or not the average value is calculated by the periodic addition means until the average value is equal to or more than the first threshold value. 2. The tension measuring device according to claim 1, further comprising: a first determination unit configured to calculate an average value in (1). 3. The natural frequency detecting means further determines whether or not the number of coincidences is equal to or greater than a second threshold value, and determines whether or not the average value is equal to or greater than the second threshold value. 3. The tension measuring device according to claim 2, further comprising a second determination unit that continues calculating the average value and sets the average value as a natural frequency when the average value exceeds a second threshold value. .