JP2875741B2 - Optical 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 measuring section for measuring a vibration waveform of an object to be measured (for example, a string or a belt-like elastic body) stretched between two points, and a measuring section for measuring the vibration waveform. The present invention relates to an optical tension measuring device comprising: a calculating unit that calculates a vibration cycle from a vibration waveform of a measurement target and calculates a tension of the measurement target.

[0002]

2. Description of the Related Art As a device for measuring the tension of a string-like or belt-like elastic body stretched between two points, a load or deflection of the elastic body is conventionally measured by a spring balance based on a material dynamic deflection calculation method. And a tension measuring device configured to measure by a length measuring device and obtain by calculation. However, the deflection calculation method is difficult and complicated, such as the need to mechanically secure a reference point for measuring the deflection,
In addition, there is a limit in accuracy, so that a tension measuring device using this calculation method is hardly used at present.

[0003] As an alternative to this, the n-order free frequency inherent to the elastic body to be measured is measured by using a sound wave or a photoelectromagnetic wave (visible light, infrared light, etc.), and the characteristic of the string is measured. There have been proposed tension measuring devices configured to obtain a tension by calculation from a vibration equation (for example, JP-A-3-61633, JP-A-62-12832, JP-A-63-11826). ).

As described above, methods of calculating the tension based on the natural vibration equation of a string are roughly classified into two methods, a method using a sound wave and a method using a photoelectromagnetic wave.

In the method using sound waves, the vibration of the sound source is measured by a sound pressure sensor, a microphone, or the like, and the frequency spectrum of the measured sound waves is analyzed. Frequency F (H
z). Then, the n-order free frequency and other necessary constants are substituted into the vibration equation of the following equation (1),
The tension of the string, which is the object to be measured, is obtained by calculation. Alternatively, the period is directly measured from the waveform of the source sound of the sound source, and the tension is calculated from the free frequency.

[0006]

F = n / (2 × L) × [(T × g) / W] ^1/2 (1) where n = vibration order (dimensionless) L = distance between two points (m T = tension (kgf) g = gravitational acceleration (m / sec ² ) w = unit weight (kgf / m) In the method using photoelectromagnetic waves, the position displacement of the object to be measured is a continuous vibration displacement waveform from the reference coordinate system. The frequency spectrum analysis of the measured vibration wave was performed as
The nth free frequency F (Hz) is obtained. Thereafter, in the same manner as in the above-described method using sound waves, each numerical value is substituted into the above equation (1), and the tension of the string to be measured is calculated.

[0007] In this case, in the above-described method using sound waves,
The measurable frequency band is 35 to 300 Hz.
When the frequency is lower than Hz (for example, 25 to 35 Hz) (lower limit audible frequency), there is a problem that the S / N is rapidly reduced and the detection becomes impossible.

[0008] In the above-described method using photoelectromagnetic waves,
CCD (ChargeCoupled Device) as light detection sensor
Image sensors and PSD (Position Sensitive Detec)
tors) There are position detection elements and others using semiconductor lasers, but all sensors are expensive and difficult to handle. In particular, there is a structural problem that involves difficulty in positioning the sensor.

Therefore, in order to solve such a problem,
In the method using a photoelectromagnetic wave, a method using a reflection type optical sensor as a light detection sensor has been proposed.

FIG. 9 shows the structure of a conventional reflection type optical sensor 70 used in an optical tension measuring device for detecting the displacement vibration of an object to be measured (for example, a transmission belt).

In the reflection type optical sensor 70, an optical axis (a direction direction maximum direction sensitivity axis) 71a of a light emitting section 71 and an optical axis (a direction direction maximum direction axis) 72a of a light receiving section 72 are connected to a stationary transmission belt 73. Measured surface 73a (measured surface 7 in this state)
The light emitting unit 71 and the light receiving unit 72 are arranged so as to intersect with each other at a certain angle on the surface where 3a is located). That is, the incident angle of the optical axis 71a (the angle with respect to the perpendicular Y intersecting at the intersection c on the reference plane A) and the optical axis 7
The light emitting unit 71 and the light receiving unit 72 are arranged so that the reflection angle of 2a (the angle with respect to the perpendicular Y intersecting at the intersection c on the reference plane A) is equal.

The reason for this arrangement is that the energy efficiency is maximized. That is, since the supply current to the light emitting diode, which is the light emitting unit 71, can be reduced, the life of the diode can be extended, and the consumption of the battery can be minimized.

In such a configuration, the transmission belt 73
, A primary vibration mode is generated around the reference plane A.

The vibration at this time is such that specular reflection on the reference plane A becomes the maximum light quantity (light reception quantity) for the light receiving unit 72, and the transmission belt 73 is located at the position farthest from the reference plane A (ie, the reflection). The regular reflection at the position closest to the mold optical sensor 70 (the position shown in FIG. 10) and the position farthest away (the position shown in FIG. 11)] is the minimum light amount (light receiving amount) for the light receiving unit 72. ).

That is, when the measured surface 73a of the transmission belt 73 moves away from the reflection type optical sensor 70 around the reference plane A or approaches the reflection type optical sensor 70 after the start of the vibration, the light receiving section 72 is used. The amount of light incident on the light source is reduced.

The output voltage level of the phototransistor as the light receiving section 72 changes linearly in proportion to the amount of incident light. Therefore, this output voltage becomes maximum when the measured surface 73a of the power transmission belt 73 is on the reference surface A, and decreases as the distance from the reference surface A increases.

That is, the relationship between the output voltage of the light receiving section 72 and the vibration of the transmission belt 73 (ie, the moving distance of the surface 73a to be measured from the reference surface A) is, as shown in FIG. The result is a chevron waveform (indicated by reference numeral 61). Due to this characteristic, the relationship between the waveform of the amount of light incident on the light receiving unit 72 (shown by reference numeral 62) due to the vibration of the transmission belt 73 and the corresponding output voltage waveform (shown by reference numeral 63) of the light receiving unit 72 is shown in FIG. As described above, the cycle of the incident light amount waveform (that is, the oscillation cycle of the transmission belt 73) T
(Sec), the cycle of the output voltage waveform is T / 2 (s)
ec).

[0018]

That is, the frequency of the output voltage waveform is twice as high as the vibration frequency of the transmission belt 73. As a method of solving this problem, there is a method of using the right half (or the left half) of the chevron characteristic shown in FIG. 12, but this method makes it difficult to set the position of the reflection type optical sensor 70, and the measurement range is also reduced. There was a problem that it was not suitable for practical use due to the narrowing.

The present invention has been made in order to solve such a problem, and an object of the present invention is to use a diffuse reflection type or omnidirectional reflection type optical sensor for the measurement unit so that the measurement unit and the object to be measured can be used. It is an object of the present invention to provide an optical tension measuring device which does not require fine adjustment of a distance to an object, accurate position setting, and the like, and enables measurement in a wide frequency band including a low frequency.

[0020]

According to a first aspect of the present invention, there is provided an optical tension measuring device for measuring a vibration waveform of a measurement object stretched between two points. Unit, the vibration period is calculated from the vibration waveform of the measurement object measured by the measurement unit, applied to an optical tension measurement device including a calculation unit that calculates the tension of the measurement object, The measuring unit includes a plurality of light emitting units and one light receiving unit, and the light receiving unit is disposed so that an optical axis thereof is orthogonal to a surface to be measured of the measurement object, Are arranged at symmetrical positions with respect to the light receiving section, and arranged such that each optical axis is orthogonal to the surface to be measured, by a diffuse reflection type or omnidirectional reflection type optical sensor. It was formed.

According to a second aspect of the present invention, there is provided an optical tension measuring apparatus according to the first aspect, wherein:
The object to be measured is a string or belt-like elastic body stretched between two points.

According to a third aspect of the present invention, in the optical tension measuring apparatus according to the first aspect, each of the light emitting units is arranged so that each of the light emitting units is arranged in a direction along the surface to be measured with the light receiving unit as a center. These are arranged at symmetrical positions.

According to a fourth aspect of the present invention, there is provided an optical tension measuring device according to the first aspect of the invention.
The respective light emitting units are arranged at symmetrical positions in a two-dimensional direction with the light receiving unit as a center.

[0024]

The operation of the optical tension measuring device according to the first aspect of the present invention will be described.

The measuring section for measuring the vibration waveform of the object to be measured is formed by a diffuse reflection type or non-directional reflection type optical sensor comprising a plurality of light emitting sections and one light receiving section. The light receiving unit is arranged so that its optical axis is orthogonal to the surface to be measured of the measurement object. In addition, each light emitting unit is arranged at a symmetrical position with the light receiving unit as a center, and arranged such that each optical axis is orthogonal to the surface to be measured. That is, the optical axes of the light emitting units and the light receiving units are arranged so as to be parallel to each other so that the optical axes do not intersect on the surface to be measured of the measurement object.

As described above, a diffuse reflection type or omnidirectional reflection type optical sensor including a plurality of light emitting units and one light receiving unit is used as a measuring unit, and the optical axes are parallel to each other.
By disposing the light emitting portion at symmetrical positions around the light receiving portion, the output voltage waveform from the light receiving portion, the conventional chevron characteristics shown in FIG. 12, a straight line characteristic which is inclined in one direction only.

With this characteristic, the relationship between the waveform of the amount of light incident on the light receiving unit due to the vibration of the object to be measured and the corresponding output voltage waveform of the light receiving unit has the same period. In addition, because of this characteristic, there is no need to provide a reference coordinate system and measure the amount of displacement as in the related art.
The arrangement position of the measurement unit with respect to the measurement target may be arbitrarily set within the measurable range. That is,
This eliminates the need for operations such as fine adjustment of the measuring unit and accurate position setting, which were conventionally required.

The operation of the optical tension measuring device according to the second aspect of the present invention will be described.

The measuring section having the above configuration is applied to the tension measurement of a string or belt-like elastic body stretched between two points.

In the case of a string or belt-like elastic body stretched between two points, the manner of string vibration is completely different depending on the shape, measurement conditions, and the like. That is, when the object to be measured is a belt, its type (toothed belt, V-shaped belt, multi-groove V-shaped belt, etc.), characteristics (long / short, weight, longitudinal elastic modulus, etc.), and measurement conditions (between two points) The vibration of the strings is completely different depending on the distance, the tension level of the object of measurement, the vibrating force, etc.), but even in such a case, the accurate vibration can be measured by using the measuring unit of the present invention. You.

The operation of the optical tension measuring device according to the third aspect of the present invention will be described.

Each light emitting unit is arranged at a symmetrical position in the direction along the surface of the object to be measured with the light receiving unit as a center. With such an arrangement, the arrangement direction of the object to be measured coincides with the arrangement direction of the light receiving unit and the light emitting unit, so that the light signals from the light emitting units arranged on both sides are substantially the same on the light receiving unit. The light is incident at the level, and the light receiving accuracy is improved.

The operation of the optical tension measuring device according to the fourth aspect of the present invention will be described.

[0034] The light-emitting portions are arranged respectively symmetrical position location of the two-dimensional direction about the light receiving portion. With such an arrangement, the measurement surface of the measurement unit (that is, the surface including the light-emitting surface of each light-emitting unit and the light-receiving surface of the light-receiving unit) is not parallel to the surface to be measured of the measurement target, and is slightly inclined. Also in this case, the light receiving accuracy of the light receiving unit can be maintained.

[0035]

An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1A and 1B show an example of the structure of a measuring section used in the optical tension measuring apparatus of the present invention. FIG. 1A is a plan view, and FIG. Is a longitudinal sectional view.

In FIG. 1, in this embodiment, two points a, b
A string or belt-shaped power transmission belt 1 supported between them is set as an object to be measured. A measuring unit 2 for measuring the vibration waveform of the transmission belt 1 is a diffuse reflection type or a non-reflective type including a plurality of (two in this embodiment) light emitting units 3 and 3 and one light receiving unit 4. It is formed by a directional reflection type optical sensor.

The light receiving section 4 is formed by a phototransistor in the present embodiment, and its optical axis (strictly speaking, the light receiving section 4).
Are arranged so that the center axis 4a of the transmission belt 1 is orthogonal to the measured surface 1a of the transmission belt 1. Further, the light emitting units 3 and 3 are formed by light emitting diodes in the present embodiment, and are symmetrical with respect to the light receiving unit 4 in the direction along the surface to be measured 1a (the symmetrical position in the left and right direction in FIG. The optical axes (strictly speaking, the central axes in the direction in which the light emitting units 3 are arranged) 3a, 3a are arranged so as to be orthogonal to the surface to be measured 1a.

The light receiving unit 4 and the light emitting units 3 and 3 are fixed to the fixed base 5 in such an arrangement state.

That is, the optical axes 3a, 3a of the light emitting portions 3, 3
And the optical axis 4a of the light receiving unit 4 are arranged in parallel with each other, and each optical axis 3a,
4a do not intersect.

In such a configuration, when the power transmission belt 1 is freely vibrated, the power transmission belt 1 has a primary vibration mode about a reference surface (the surface on which the measured surface 1a of the power transmission belt 1 is stationary) A as a center. Occurs.

The vibration at this time is caused by the transmission belt 1
Of the surface 1a to be measured farthest from the measuring unit 2 (reference numeral 1)
b), the light amount (light receiving amount) is the minimum for the light receiving unit 4, and the measured surface 1a of the transmission belt 1 is measured.
Is the position closest to the measuring unit 2 (indicated by reference numeral 1c).
, The light amount becomes the maximum light amount (light reception amount) for the light receiving unit 4.

Accordingly, the output voltage of the light receiving section 4 becomes maximum when the measured surface 1a of the power transmission belt 1 is closest to the measuring section 2, and decreases linearly as the distance from the measuring section 2 increases.
It becomes minimum when it is farthest from the measuring unit 2.

That is, the relationship of the output voltage of the light receiving section 4 to the vibration of the transmission belt 1 (ie, the moving distance of the surface to be measured 1a from the measuring section 2) is within the measurable range as shown in FIG. It has a linear characteristic (shown by reference numeral 51) that slopes downward and to the right. That is, since it is not necessary to consider the reference plane A as shown in the related art, it is possible to arbitrarily set the distance of the measuring unit 2 to the measured surface 1a of the transmission belt 1 within the measurable range. Become.

Then, due to this characteristic, the waveform of the amount of light incident on the light receiving section 3 due to the vibration of the transmission belt 1 (indicated by reference numeral 52) and the corresponding output voltage waveform of the light receiving section 3 (indicated by reference numeral 53) The relationship is the same cycle T (sec)
Waveform.

FIG. 2 shows an electrical configuration of an optical tension measuring device provided with the measuring section 2 having such a structure.

In the figure, the output of an oscillating circuit 11 oscillating at a predetermined frequency is guided via an amplifier circuit 12 to an AGC circuit 13 for adjusting the output level to a constant level. Are connected to the anode side of the two light emitting diodes 3 and 3 connected in series.
The cathodes of the light emitting diodes 3 and 3 connected in series are connected to the ground potential.

On the other hand, the phototransistor 4 has a collector connected to the power supply voltage Vcc, and an emitter connected to the amplifier circuit 1.
4 to the demodulation circuit 15. The output of the demodulation circuit 15 is fed back to the AGC circuit 13 as a control voltage, and is guided to a microprocessor (not shown) that controls the entire system via an amplifier circuit 16. The microprocessor executes various arithmetic processes such as calculating the tension of the transmission belt 1 from a vibration cycle based on the measured vibration waveform.

In this embodiment, the oscillation frequency of the oscillation circuit 11 is set to 5.6 kHz pulse oscillation so that the minute vibration of the transmission belt 1 can be read accurately and the effective measurement range can be made as wide as possible. That is, the lighting method of the light emitting diodes 3 and 3 is a pulse lighting method of 5.6 kHz. However, the oscillation frequency of the oscillation circuit 11 only needs to be around 5.6 kHz, and is 5.6 kHz.
It is not limited to z.

The AGC circuit 13 adjusts the pulse input voltage to the light emitting diodes 3 and 3 based on the signal from the demodulation circuit 15 so that the output of the phototransistor 4 becomes constant. By the function of the AGC circuit 13, even if the distance between the measuring unit 2 and the measured surface 1a of the power transmission belt 1 fluctuates, it is possible to accurately read the fine vibration of the power transmission belt 1.

Next, the operation of the optical tension measuring device having the above configuration will be described.

First, when the transmission belt 1 is freely vibrated,
A primary vibration mode is generated around the reference plane A.

In this state, the oscillation circuit 11 outputs
As shown in FIG. 4, a 5.6 kHz pulse signal (reference numeral 5)
4) is oscillated. This pulse signal 54 is
After being amplified by the amplifier circuit 12 to a level necessary for the subsequent processing, the output level is adjusted to a constant level by the AGC circuit 13 and supplied to the light emitting diodes 3 and 3 of the measuring unit 2. The light emitting diodes 3 and 3 are turned on according to the given pulse signal 54, and the power transmission belt 1 is turned on.
Will be irradiated with light. That is, the optical signal emitted from the light emitting diodes 3 and 3 is a carrier having the same waveform as the pulse signal 54 shown in FIG.

The optical signal is diffusely reflected (or omnidirectionally reflected) on the surface to be measured 1a of the vibrating transmission belt 1 and a part thereof is received by the phototransistor 4. At this time, an optical signal received by the phototransistor 4 has a belt vibration waveform (reference numeral 55) as shown in FIG.
), The carrier (pulse signal 54) is an amplitude-modulated signal.

The amplitude-modulated signal is supplied to the demodulation circuit 15
, Only the vibration wave 55 of the belt is extracted. Then, the vibration cycle of the extracted belt vibration wave 55 is measured by a synchronization circuit or a counter circuit (not shown), and the measured vibration cycle is taken in as a digital signal by a microprocessor (not shown). .

The microprocessor executes arithmetic processing such as calculating the tension of the transmission belt 1 from the measured vibration period. However, the calculation processing here is the same as the processing that has been performed conventionally, and thus detailed description is omitted.

Here, when the object to be measured is a string-like or belt-like elastic body (the transmission belt 1) stretched between two points,
As described in the above operation, the state of the string vibration is completely different depending on the shape, the measurement conditions, and the like. That is,
When the object to be measured is a belt, its type (toothed belt, V-shaped belt, multi-groove V-shaped belt, etc.), characteristics (long / short, weight, longitudinal elastic modulus, etc.), and measurement conditions (distance between two points) , The tension level of the object of measurement, the vibrating force, etc.), the string vibration is attenuated rapidly, and the string vibration is sustained moderately. When the string vibration suddenly attenuates and stops, a situation occurs in which the number of vibration period data read by the microprocessor becomes insufficient.

Therefore, the present embodiment has a function of displaying a screen on a liquid crystal display or the like so as to prompt the measurer to perform an appropriate operation in such a case. That is, when the number of data is insufficient, the measurer is instructed to repeat the measurement, thereby supplementing the number of captured data, and obtaining appropriate vibration cycle data by averaging calculation processing. .

FIG. 6 shows an example of the external configuration of the optical tension measuring device of the present invention.

In the figure, reference numeral 21 denotes a reflection type optical sensor incorporating the measuring unit 2 which is a feature of the present invention, and reference numeral 22 denotes a sensor amplifier unit incorporating each circuit block shown in FIG. And is integrated. Reference numeral 23 denotes a main body, on which a microprocessor is mounted. Reference numeral 24 denotes a connector for connection to a detection head cable, reference numeral 25 denotes a connector for connection to a printer, and reference numeral 2 denotes a connector.
Reference numeral 6 denotes a liquid crystal display, and reference numeral 27 denotes a keyboard.

In the above embodiment, the measuring section 2 is described as a diffuse reflection type or non-directional reflection type optical sensor composed of two light emitting sections 3 and 3 and one light receiving section 4. However, as shown in FIG. 7, it is possible to adopt a configuration in which four light emitting units 3 are arranged at symmetrical positions with respect to the light receiving unit 4, or a configuration in which an even number more than that are arranged. However, the number of the light emitting units 3 is not limited to an even number, and the light emitting units 3 do not necessarily have to be symmetrical with respect to the light receiving unit 4. For example, a pair of the light emitting unit 3 and the light receiving unit 4 is connected to the measured surface 1a of the transmission belt 1.
May be arranged at right angles to the
One on one side of the center, two light emitting portions on the other side of the 3, 3 may be arranged respectively.

As described above, in any arrangement, since the direction in which the transmission belt 1 is stretched and the direction in which the light emitting unit 3 and the light receiving unit 4 are arranged coincide with each other, the light receiving unit 4 is arranged on both sides. The light signals from the light emitting units 3, 3,... Are incident at almost the same level, and the light receiving accuracy is improved.

The position of the light emitting section 3 is as shown in FIG.
(A) and not the linear arrangement as shown in FIG.
It is possible to adopt a configuration in which a plurality of light emitting units 3, 3,... Are arranged at symmetrical positions in the two-dimensional direction with respect to the light receiving unit 4. For example, as shown in FIG. 8, three light emitting units 3, 3, 3
3 can be arranged. Similarly, a configuration in which four light-emitting units 3, 3,... Are arranged at 90-degree intervals and five light-emitting units 3, 3,. It is. That is, the symmetrical position in the two-dimensional direction centering on the light receiving unit 4 means that a plurality of light emitting units 3, 3... Are arranged at equidistant positions on a concentric circle centering on the light receiving unit 4. It means that.

By arranging in this manner, the measuring surface of the measuring unit 2 (ie, the light emitting surfaces of the light emitting units 3, 3... Are not parallel and slightly inclined, the light receiving accuracy of the light receiving section 4 can be maintained.

Further, in the above embodiment, the vibration of the transmission belt 1 as the object to be measured is limited to the primary vibration mode, the vibration period of only the fundamental frequency is calculated, and the frequency analysis circuit and the like are omitted. It has a configuration. In addition, as a result of focusing on the vibration period, the measurement of the absolute displacement amount becomes a secondary problem, and the complicated and expensive sensor device and the like shown in the related art become unnecessary.

[0066]

According to the present invention, there is provided an optical tension measuring device for measuring a vibration waveform of a measurement object stretched between two points, and a vibration waveform of the measurement object measured by the measurement unit. and calculate a more vibration period, and a calculation unit for calculating the tension of the measurement object, wherein the measurement unit, composed of a few light-emitting portion double and one light receiving portion, the light receiving portion, that The optical axis is arranged so as to be orthogonal to the surface to be measured of the object to be measured, and each of the light emitting units is arranged at a symmetrical position in a direction along the surface to be measured with the light receiving unit as a center. It is formed by a diffuse reflection type or omnidirectional reflection type optical sensor arranged so that an optical axis is orthogonal to the surface to be measured. Therefore, the relationship between the output voltage of the light receiving unit and the vibration of the measurement object (that is, the movement distance of the measurement surface of the measurement object from the measurement unit) has a linear characteristic that is inclined in one direction within the measurable range. . This characteristic eliminates the need for operations such as fine adjustment and fixed position adjustment in consideration of the reference plane as shown in the related art, so that the arrangement distance of the measurement unit with respect to the measurement object can be set within the measurable range. Can be set to Also, due to this characteristic, the relationship between the waveform of the amount of light incident on the light receiving unit due to the vibration of the measurement object and the corresponding output voltage waveform of the light receiving unit has a waveform having the same period. That is, the disadvantage that the oscillation cycle of the measurement object is measured at twice the cycle is eliminated. Further, since the measuring section can be formed of a low-cost member such as a combination of a light emitting diode and a phototransistor, the manufacturing cost of the entire apparatus can be reduced correspondingly. Furthermore, unlike the sound wave type tension measuring device, it is not affected by the surrounding noise, and a wide band (3 to 1000 Hz) tension measurement including a low frequency (3 to 30 Hz) which cannot be measured by the sound wave type can be performed. Become.

Further, the optical tension measuring device of the present invention is configured such that each light emitting section is arranged at a symmetrical position in the direction along the surface to be measured of the object to be measured with the light receiving section as a center. Since the arrangement direction of the object coincides with the arrangement direction of the light receiving unit and the light emitting unit, the light signals from the light emitting units arranged on both sides are incident on the light receiving unit at substantially the same level, The light receiving accuracy is improved.

In the optical tension measuring apparatus of the present invention, each light emitting section is arranged symmetrically in a two-dimensional direction with the light receiving section as a center. Even when the measurement surface of the measurement unit (that is, the surface including the light-emitting surface of each light-emitting unit and the light-receiving surface of the light-receiving unit) is not parallel and slightly inclined, it is possible to maintain light-receiving accuracy in the light-receiving unit. The effect is achieved.

[Brief description of the drawings]

1A and 1B are a plan view and a vertical sectional view showing an example of a structure of a measuring unit used in an optical tension measuring device of the present invention.

FIG. 2 is a block diagram showing an electrical configuration of an optical tension measuring device including a measuring unit having the structure shown in FIG.

FIG. 3 is a characteristic diagram illustrating a relationship between an output voltage of a light receiving unit and a vibration of a transmission belt.

FIG. 4 is a waveform diagram showing a pulse signal oscillated from an oscillation circuit.

FIG. 5 is a waveform diagram showing an optical signal received by a phototransistor.

FIG. 6 is an external configuration diagram of an optical tension measuring device of the present invention.

FIG. 7 is a plan view showing another embodiment of the measuring unit.

FIG. 8 is a plan view showing still another embodiment of the measuring section.

FIG. 9 is an explanatory view showing a structure of a conventional reflection type optical sensor used for an optical tension measuring device.

FIG. 10 is an explanatory diagram showing how light is reflected when the transmission belt comes closest to a conventional reflection-type optical sensor.

FIG. 11 is an explanatory diagram showing how light is reflected when the transmission belt is farthest from a conventional reflection-type optical sensor.

FIG. 12 is a characteristic diagram illustrating a relationship between output voltage of a light receiving unit and vibration of a transmission belt in a conventional reflection type optical sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power transmission belt (measurement object) 1a Surface to be measured 2 Measuring unit 3 Light emitting unit (light emitting diode) 3a Optical axis 4 Light receiving unit (phototransistor) 4a Optical axis

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01L 5/04-5/10

Claims (4)

(57) [Claims] A measuring unit configured to measure a vibration waveform of a measurement object stretched between two points; and a vibration cycle calculated from the vibration waveform of the measurement object measured by the measurement unit, and performing the measurement. An optical tension measuring device comprising: a calculating unit that calculates a tension of the object; wherein the measuring unit includes a plurality of light emitting units and one light receiving unit, and the optical axis of the light receiving unit is The light emitting units are arranged so as to be orthogonal to the surface to be measured of the measurement object,
Each is arranged at a symmetrical position around the light receiving section, and each optical axis is arranged so as to be orthogonal to the surface to be measured, and is formed by a diffuse reflection type or omnidirectional reflection type optical sensor. An optical tension measuring device, characterized in that: 2. The optical tension measuring device according to claim 1, wherein the object to be measured is a string-like or belt-like elastic body stretched between two points. 3. The optical tension measuring apparatus according to claim 1, wherein each of the light emitting units is disposed at a symmetric position in a direction along the surface to be measured with the light receiving unit as a center. 4. The optical tension measuring device according to claim 1, wherein each of the light emitting units is disposed at a symmetric position in a two-dimensional direction with the light receiving unit as a center.