JP2004205321A - Length measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a length measuring device capable of performing highly accurate length measurement with a simple constitution. <P>SOLUTION: Each pair of a first detection part 242 and a second detection part 243 is provided at unchangeable intervals with a support 241 made of a low expansion material on one end of a low-expansion magnetostrictive delay line 210 having a magnetostrictive characteristic. A pulse current is supplied into the magnetostrictive delay line 210 by a pulse current generation means 220, to thereby generate an ultrasonic wave by an ultrasonic wave generation magnetic body 230 provided integrally on a movable body. Voltage pulses are generated respectively at the first detection part 242 and the second detection part 243 by the ultrasonic wave propagating in the magnetostrictive delay line 210. Propagation times from supply of the pulse current to generation of the voltage pulses are operated respectively by performing time integration at an integration part, and the distance from the ultrasonic wave generation magnetic body 230 to the first detection part 242 is operated by a calculation part 330 based on the distance between the first detection part 242 and the second detection part 243. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a length measuring device using a magnetostrictive delay line.
[0002]
[Background Art]
Conventionally, for example, as a length measuring device for measuring the length of an object to be measured, a scale is manufactured by patterning information on the measured length, and the manufactured scale is detected electrically or optically to measure the length. A configuration for measuring is known. In order to measure a long distance, it is necessary to accurately produce a pattern with the same length as the measurement range, which requires a large processing machine. There is a problem that reduction cannot be achieved. Therefore, a length measuring device that does not use a scale is being studied (for example, see Non-Patent Document 1).
[0003]
The length measuring device described in Non-Patent Document 1 uses a magnetostrictive delay line as shown in FIG. 5, for example. That is, in FIG. 5A, the length measuring device 900 includes the ultrasonic driving coil N₀And the first detection coil N₁And the second detection coil N_TwoAnd Ultrasonic drive coil N₀Is provided on a movable body that moves along the magnetostrictive delay line 910 (in the horizontal direction in FIG. 5). A first detecting coil N is provided at both ends of the magnetostrictive delay line 910.₁And the second detection coil N_TwoAre arranged respectively. And the ultrasonic drive coil N₀And the first detection coil N₁And the second detection coil N_Two, The position of the movable body is measured. Here, as the magnetostrictive delay line 910 for propagating the ultrasonic wave, a wire or a pipe having magnetostrictive characteristics such as nickel is used, and the conversion of the electric signal and the ultrasonic wave can be simply configured by winding a coil.
[0004]
Then, the position of the movable body is measured as described below. That is, the voltage pulse V is applied to the primary coil of the transformer CT1._iIs applied, the current i flows through a closed loop including the magnetostrictive delay line 910 corresponding to the secondary coil._TwoFlows. In this closed loop, since the transformer CT2 forms the primary winding, an electromotive force is generated in the secondary winding of the transformer CT2, and the ultrasonic driving coil N₀The pulse current i₀Is supplied. And the ultrasonic drive coil N₀The pulse current i₀Flows, the ultrasonic drive coil N₀A longitudinal ultrasonic wave, which is a local mechanical strain, is generated by a magnetostrictive effect at a lower portion of the lower part, and propagates along a magnetostrictive delay line 910. This longitudinal wave ultrasonic wave is applied to the first detection coil N.₁Alternatively, the second detection coil N_Two, A magnetic flux changes in the magnetostrictive delay line 910 to which the bias magnetic field is applied by the permanent magnet 950 due to the magnetostrictive effect, and a voltage pulse is generated. This allows the voltage pulse V_iFrom the point of occurrence of the first detection coil N₁Alternatively, the second detection coil N_TwoBy measuring the time until the voltage pulse is generated in the above, the propagation time is obtained.
[0005]
Here, the displacement x of the movable body is determined by using the ultrasonic driving coil N from the center of the magnetostrictive delay line 910.₀The displacement x is given by the following equation (1). Note that the following Equation 1 is required to slightly modify the equation described in Non-Patent Document 1, but a detailed description of the calculation will be omitted.
[0006]
(Equation 1)
x = L / 2 * ((t₁-T_Two) / (T₁+ T_Two))
L: first detection coil N₁And the second detection coil N_TwoDistance between
t₁: Ultrasonic drive coil N₀To the first detection coil N₁Propagation time to
t_Two: Ultrasonic drive coil N₀To the second detection coil N_TwoPropagation time to
[0007]
As is apparent from the equation shown in Expression 1, the first detection coil N₁And the second detection coil N_TwoIf the distance L between them is known, the first detection coil N₁And the second detection coil N_TwoPropagation time t₁, T_Two, The displacement x is obtained, that is, the position of the movable body is measured.
[0008]
[Non-patent document 1]
Rora Ueda, "Displacement transducer using magnetostrictive delay line"
Transactions of the Society of Instrument and Control Engineers, Vol. 17, No. 8, November 1981, P70-P76
[0009]
[Problems to be solved by the invention]
However, according to Non-Patent Document 1, when a temperature change occurs, the first detection coil N serving as a length reference is used.₁And the second detection coil N_TwoThe distance L between them also changes, and it may not be possible to measure the length with high accuracy. Therefore, in order to enhance stability against temperature change, the first detection coil N₁And the second detection coil N_TwoMay be supported by a low expansion material. However, the first detection coil N₁And the second detection coil N_TwoAre arranged at both ends of the magnetostrictive delay line 910, it is necessary to devise measures such as enlarging the size so as not to affect the movement of the movable body. An example is a problem in which it is difficult to provide a configuration that enhances stability.
[0010]
In view of the above, an object of the present invention is to provide a length measuring device capable of measuring a length with high accuracy with a simple configuration.
[0011]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided a longitudinal magnetostrictive delay line, an ultrasonic wave generating means for generating an ultrasonic wave in the magnetostrictive delay line, and an interval in which one end of the magnetostrictive delay line in the longitudinal direction cannot be varied. And a pair of detecting means for detecting ultrasonic waves propagating through the magnetostrictive delay line, respectively, and calculating a distance from a position where the ultrasonic wave is generated on the magnetostrictive delay line by the ultrasonic generating means to the detecting means. And a calculating means for performing the measurement.
[0012]
According to the present invention, a pair of detecting means are provided, in which an ultrasonic wave is generated in a magnetostrictive delay line by an ultrasonic wave generating means and propagated through the magnetostrictive delay line, and an ultrasonic wave is provided at one end in the longitudinal direction of the magnetostrictive delay line. The length is measured by calculating the distance from the position where the ultrasonic waves are generated by the calculating means to the detecting means. By this, the operation of generating ultrasonic waves in the magnetostrictive delay line by the ultrasonic wave generating means by the ultrasonic wave generating means by the detecting means provided with the distance invariable is not affected, and the distance between the pair of detecting means provided together is reduced. For example, the configuration in which the temperature is not changed even if a temperature change occurs is simple, and a highly accurate length measurement can be easily obtained with a simple configuration.
[0013]
According to a second aspect of the present invention, in the length measuring device according to the first aspect, the arithmetic unit propagates from generation of the ultrasonic wave by the ultrasonic wave generation unit to detection of the ultrasonic wave by the pair of detection units. A distance is calculated based on a time and a distance between the pair of the detection units.
[0014]
In the present invention, the ultrasonic wave is applied to the magnetostrictive delay line by the arithmetic means based on the propagation time from the generation of the ultrasonic wave by the ultrasonic wave generating means to the detection of the ultrasonic wave by the pair of detecting means, and the distance between the pair of detecting means. Calculate the distance from the position where is generated to the detecting means. This makes it possible to easily measure the length using the magnetostrictive delay line.
[0015]
According to a third aspect of the present invention, in the length measuring device according to the second aspect, the arithmetic unit propagates from generation of the ultrasonic wave by the ultrasonic wave generation unit to detection of the ultrasonic wave by the pair of detection units. The time is calculated by time integration.
[0016]
In the present invention, the propagation time from the generation of the ultrasonic wave by the ultrasonic wave generation means to the detection of the ultrasonic wave by the pair of detection means is calculated by the time integration by the calculation means. As a result, the propagation time can be easily obtained, and the calculation of the length measurement can be easily performed using the obtained propagation time without using a factor affected by a temperature change.
[0017]
According to a fourth aspect of the present invention, in the length measuring apparatus according to the second aspect, the calculating means includes an oscillator for generating a reference frequency, and the pair of the oscillators generating an ultrasonic wave based on the reference frequency from the oscillator. And a counter for measuring a propagation time until the detection of the ultrasonic wave by the detecting means.
[0018]
According to the present invention, the propagation time is acquired by measuring the time from the generation of the ultrasonic wave to the detection of the ultrasonic wave by the pair of detection means by the counter based on the reference frequency generated from the oscillator. As a result, the propagation time can be easily obtained, and the calculation of the length measurement can be easily performed using the obtained propagation time without using a factor affected by a temperature change.
[0019]
According to a fifth aspect of the present invention, there is provided a magnetostrictive delay line having a longitudinal shape, an ultrasonic wave generating means for generating ultrasonic waves in the magnetostrictive delay line, and one end of the magnetostrictive delay line at one longitudinal end of the magnetostrictive delay line. A detecting unit provided at a predetermined position to detect ultrasonic waves propagating through the magnetostrictive delay line, and a distance from the position at which ultrasonic waves are generated to the magnetostrictive delay line by the ultrasonic generating unit to the detecting unit. A calculating means for calculating based on a propagation time from generation of ultrasonic waves to detection of ultrasonic waves by the detection means and a propagation time from generation of ultrasonic waves to detection of ultrasonic waves reflected at one end of the magnetostriction delay line, A length measuring device characterized by comprising:
[0020]
According to the present invention, the ultrasonic wave generated by the ultrasonic wave generating means is detected by the detecting means provided at a predetermined position from one end in the longitudinal direction of the magnetostrictive delay line, and the ultrasonic wave propagating through the magnetostrictive delay line is detected and calculated. By the means, based on the propagation time from the generation of the ultrasonic wave to the detection and the propagation time from the generation of the ultrasonic wave to the detection of the ultrasonic wave reflected at one end of the magnetostriction delay line, from the position where the ultrasonic wave is generated to the detection means Calculate the distance. As a result, the operation of generating an ultrasonic wave on the magnetostrictive delay line by the detecting means provided at a predetermined position from one end of the magnetostrictive delay line is not affected. A configuration in which the propagation time does not fluctuate can be easily obtained, for example, by forming a magnetostrictive delay line using a low expansion material, and a highly accurate length measurement can be easily obtained with a simple configuration.
[0021]
According to a sixth aspect of the present invention, in the length measuring device according to any one of the first to fifth aspects, the magnetostrictive delay line is made of a low expansion material having a magnetostrictive characteristic or a low expansion material and a magnetostrictive metal. It is characterized by being formed of a composite material.
[0022]
According to the present invention, the magnetostrictive delay line is formed of a low expansion material having a magnetostrictive property or a composite material of a low expansion material and a magnetostrictive metal. As a result, an error due to a dimensional change in the length direction of the magnetostrictive delay line due to a temperature change can be suppressed, and a more accurate length measurement can be obtained.
[0023]
According to a seventh aspect of the present invention, in the length measuring device according to any one of the first to sixth aspects, the magnetostrictive delay line has a temperature adjusting unit.
[0024]
In the present invention, the temperature adjustment means is provided in the magnetostrictive delay line. As a result, the temperature of the magnetostrictive delay line is kept constant by the temperature adjusting means, and an error due to a dimensional change in the length direction of the magnetostrictive delay line due to a temperature change is suppressed. Is obtained.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the length measuring device of the present invention will be described with reference to the drawings.
[0026]
[First Embodiment]
(Configuration of length measuring device)
FIG. 1 is a schematic diagram illustrating a schematic configuration of a length measuring device according to the present embodiment. In FIG. 1, reference numeral 100 denotes a length measuring device. The length measuring device 100 includes a measuring unit 200 and an arithmetic unit 300 as arithmetic means. The measuring unit 200 includes a magnetostrictive delay line 210, a pulse current generating unit 220, a magnetic body 230 for generating ultrasonic waves, and an internal length reference unit 240. The arithmetic unit 300 includes an integrating unit 310, a converter 320, a calculating unit 330, and a display unit 340. Note that the pulse current generating means 220 and the ultrasonic wave generating magnetic body 230 constitute the ultrasonic wave generating means of the present invention.
[0027]
The magnetostriction delay line 210 of the measuring unit 200 is a long line along a movement path of a movable body (not shown), a wire or pipe having a magnetostrictive property such as nickel, a low expansion material having a magnetostriction property, or a low expansion material. A composite material with a magnetostrictive metal such as nickel, for example, a material obtained by bonding a nickel thin plate to crystallized glass such as Zerodur (trade name: made by Deutsche Schott) or a mixed material in which a low expansion material and a magnetostrictive metal are mixed It is formed by a formed one. Further, the magnetostrictive delay line 210 is provided with a temperature adjusting unit (not shown) so as not to be affected by an external temperature change. As the temperature adjusting means, any configuration that keeps the temperature constant by, for example, providing a heat pipe substantially coaxially within the magnetostrictive delay line 210 or providing a cooling pipe through which a refrigerant can flow can be used. . In a situation where the temperature does not change due to air conditioning or the like, the temperature adjusting means may not be provided.
[0028]
The pulse current generating means 220 is connected to the magnetostrictive delay line 210 so that a pulse current can be supplied. The pulse current generating means 220 is connected so as to be able to supply a pulse current within a range in which, for example, a magnetic body 230 for generating an ultrasonic wave to be described later moves.
[0029]
The ultrasonic generating magnetic body 230 is formed in a substantially cylindrical shape having different polarities on both end faces in the axial direction, for example, of a ferromagnetic material, and is integrally attached to the movable body. The magnetic body 230 for ultrasonic wave generation is disposed movably along the magnetostrictive delay line 210 in a state where the magnetostrictive delay line 210 is inserted on the inner peripheral side. An ultrasonic wave is generated by a pulse current flowing through the horn.
[0030]
The internal length reference unit 240 includes a support 241, a first detection unit 242 as a detection unit, and a second detection unit 243 as a detection unit. The support 241 is formed of a low expansion member, and integrally supports the first detection unit 242 and the second detection unit 243. Examples of the low-expansion member include a crystal such as Invar, which is a low-expansion alloy composed of 36% nickel, 0.35% manganese, and iron containing a small amount of carbon and other elements, and Zerodur (trade name) described above. Examples include fossilized glass. The distance between the first detector 242 and the second detector 243 is kept constant by the support 241. The support 241 is not limited to the case where the first detection unit 242 and the second detection unit 243 are integrally supported, and the distance between the first detection unit 242 and the second detection unit 243 is kept constant. Any supporting method can be used as long as it is relatively immovable in the state in which it is performed.
[0031]
The first detector 242 includes a first winding 242A and a first magnetic body for bias 242B. The first winding 242A is wound around one end of the magnetostrictive delay line 210 in the longitudinal direction, is connected to the arithmetic unit 300, and outputs an electric signal to the arithmetic unit 300. The first biasing magnetic body 242B is disposed close to the first winding 242A, and generates a bias magnetic field in the magnetostrictive delay line 210. Then, the first detecting unit 242 generates a voltage pulse in the first winding 242A by the magnetostriction effect of the ultrasonic wave because the bias magnetic field is applied by the first magnetic body for bias 242B and the magnetic flux changes. Is generated, and a signal of the generated voltage pulse is output to the arithmetic unit 300.
[0032]
The second detector 243 includes a second winding 243A and a second bias magnetic body 243B. The second winding 243A is wound around one end of the magnetostrictive delay line 210 in the longitudinal direction adjacent to the first winding 242A, and is connected to the arithmetic unit 300 to output an electric signal to the arithmetic unit 300. The second magnetic body for bias 243B is disposed close to the second winding 243A, and generates a bias magnetic field in the magnetostrictive delay line 210. The second detecting unit 243 generates a voltage pulse by the second winding 243A due to the magnetostriction effect of the ultrasonic wave because the bias magnetic field is applied by the second bias magnetic body 243B and the magnetic flux changes. Is generated, and a signal of the generated voltage pulse is output to the arithmetic unit 300.
[0033]
On the other hand, the integration section 310 of the calculation section 300 includes a first integrator 311 and a second integrator 312. The first integrator 311 is connected to the first winding 242A of the first detection unit 242, acquires a voltage pulse from the first winding 242A, and performs an arithmetic processing on the voltage pulse signal by time integration. do. By this arithmetic processing, as shown in FIG. 1, after the pulse current is supplied to the magnetostrictive delay line 210 by the pulse current generating means 220, the ultrasonic wave generated by the ultrasonic wave generating magnetic body 230 is applied to the first winding 242A. Propagation time t until the voltage pulse is output_aIs required. The second integrator 312 is connected to the second winding 243A of the second detector 243, acquires a voltage pulse from the second winding 243A, and integrates the voltage pulse signal by time integration. Perform arithmetic processing. By this arithmetic processing, as shown in FIG. 1, after the pulse current is supplied to the magnetostrictive delay line 210 by the pulse current generating means 220, the ultrasonic wave generated by the ultrasonic generating magnetic body 230 is converted into the second winding 243A. Propagation time t until the voltage pulse is output_bIs required. The first integrator 311 and the second integrator 312 are connected to the converter 320, and output a signal of a calculation result to the converter.
[0034]
The converter 320 includes a first A / D (analog / digital) converter 321 and a second A / D converter 322. Then, the first A / D converter 321 is connected to the first integrator 311 and converts a signal output from the first integrator 311 into a digital signal. Similarly, the second A / D converter 322 is connected to the second integrator 312 and converts a signal output from the second integrator 312 into a digital signal. The first A / D converter 321 and the second A / D converter 322 are connected to the calculation unit 330, respectively.
[0035]
The calculating unit 330 is, for example, a CPU (Central Processing Unit), which outputs a signal from the ultrasonic generating magnetic body 230 based on digital signals output from the first A / D converter 321 and the second A / D converter 322. The distance x to the first winding 242A of the first detection unit 242 is calculated. That is, the calculation is performed based on the following equation (2). The calculation result of the distance x calculated by the calculation unit 330 is appropriately output to the display means 340 and displayed on the screen.
[0036]
(Equation 2)
x = (t_a/ (T_b-T_a)) * L
x: distance from the ultrasonic generating magnetic body 230 to the first winding 242A
t_a: Propagation time from the ultrasonic generating magnetic body 230 to the first winding 242A
t_b: Propagation time from the ultrasonic generating magnetic body 230 to the second winding 243A
l: distance between the first winding 242A and the second winding 243A
[0037]
Here, the formula of the distance x calculated by the calculation unit 330 will be described. The distance x from the ultrasonic generating magnetic body 230 to the first winding 242A is expressed by the following equation (3) from the relationship between speed and time.
[0038]
(Equation 3)
x = Vt_a
x: distance from the ultrasonic generating magnetic body 230 to the first winding 242A
V: sound velocity in the magnetostrictive delay line 210
[0039]
Similarly, the distance (x + 1) from the ultrasonic generating magnetic body 230 to the second winding 243A of the second detector 243 is expressed as shown in the following Expression 4.
[0040]
(Equation 4)
(X + 1) = Vt_b
(X + 1): distance from the ultrasonic generating magnetic body 230 to the second winding 243A
t_b: Propagation time from the ultrasonic generating magnetic body 230 to the second winding 243A
[0041]
From the expressions shown in Expressions 3 and 4, as shown in Expression 5 below, an expression irrelevant to the sound speed can be obtained by deleting the term of the sound speed in the magnetostrictive delay line 210.
[0042]
(Equation 5)
x / t_a= (X + 1) / t_b
[0043]
Therefore, based on the equation (5), the distance x from the ultrasonic generating magnetic body 230 to the first winding 242A irrespective of the sound speed that changes with temperature is obtained as shown in the equation (2).
[0044]
(Operation of length measuring device)
Next, the operation of the length measuring device of the above embodiment will be described with reference to FIG. FIG. 2 is a timing chart showing an operation for calculating the distance x between the position of the ultrasonic wave generating magnetic body and the first winding.
[0045]
The magnetostrictive delay line 210 is arranged corresponding to the position where the length is measured, and the movable body is moved with reference to the internal length reference means 240. In this state, as shown in FIG. 2A, a pulse current is supplied to the magnetostrictive delay line 210 by the pulse current generating means 220. By the supply of the pulse current, an ultrasonic wave is generated from the ultrasonic generation magnetic body 230 provided integrally with the movable body. The generated ultrasonic wave propagates through the magnetostrictive delay line 210 and reaches the internal length reference means 240. Then, first, the first winding 242A of the first detection unit 242 transmits the ultrasonic wave transmitted to the magnetostrictive delay line 210 in which the bias magnetic field is applied by the first bias magnetic body 242B and the magnetic flux changes. As a result, a voltage pulse is generated as shown in FIG. Next, the second winding 243A of the second detection unit 243 generates a voltage pulse similarly as shown in FIG. 2C.
[0046]
Then, as shown in FIGS. 2D and 2E, the first integrator 311 and the second integrator 312 of the arithmetic unit 300 start supplying the pulse current by the pulse current generating means 220. The time integral is calculated until the input of a voltage pulse equal to or more than a predetermined threshold value generated in the first winding 242A and the second winding 243A. The threshold value is such that, for example, a voltage pulse generated again in the first winding 242A and the second winding 243A by the ultrasonic wave reaching and reflecting to one end of the magnetostrictive delay line 210 is equal to the first integrator 311 and the second integrator 311. The integrator 312 is set to a value that is not used for the time integration calculation. Then, the first A / D converter 321 and the second A / D converter 322 of the arithmetic unit 300 convert the arithmetic value obtained by the time integration into a digital value. Thereafter, based on the obtained digital value, the calculation unit 330 calculates the distance x using the above-described equation 2, and the display means 340 displays the calculation result on the screen.
[0047]
(Operation and effect of the length measuring device)
As described above, in the above-described embodiment, the pulse current generating unit 220 supplies a pulse current to the magnetostrictive delay line 210 and the ultrasonic current generating magnetic body 230 located at a predetermined position with respect to the magnetostrictive delay line 210. A pair of first ultrasonic waves is generated by transmitting the ultrasonic waves propagating through the magnetostrictive delay line 210 to the one end in the longitudinal direction of the magnetostrictive delay line 210 and supported by the support 241 so that the interval is not variable. The detection unit 242 and the second detection unit 243 detect the length, and the calculation unit 300 calculates the distance x from the position where the ultrasonic wave is generated to the first detection unit 242 to measure the length.
[0048]
For this reason, the first detection unit 242 and the second detection unit 243, which are provided with the intervals invariable, allow the ultrasonic generation magnetic body 230 that generates ultrasonic waves to move relative to the magnetostrictive delay line 210. Ultrasonic waves can be easily generated without any influence, and the distance between a pair of the first and second detectors 242 and 243 provided side by side is arranged so as not to fluctuate even if a temperature change occurs. The structure can be simply supported by the supporting member 241 having a low coefficient of thermal expansion, and highly accurate length measurement can be easily performed with the simple structure.
[0049]
Then, an ultrasonic wave is generated by the ultrasonic generating magnetic body 230 by a pulse current supplied by the pulse current generating means 220, and then the ultrasonic wave is generated by the pair of first detection unit 242 and second detection unit 243. Propagation time t until each is detected_a, T_bFrom the position where ultrasonic wave is generated in the magnetostrictive delay line 210 by the arithmetic unit 300 based on the distance l between the pair of the first detection unit 242 and the second detection unit 243 where measurement is easy, the first The distance x to the detection unit 242 is calculated. Therefore, the length can be easily measured using the magnetostrictive delay line 210.
[0050]
Further, after the ultrasonic waves are generated by the ultrasonic generating magnetic body 230 by the pulse current supplied by the pulse current generating means 220, the ultrasonic waves are generated by the pair of the first detection unit 242 and the second detection unit 243. Propagation time t until each is detected_a, T_bIs calculated by time integration in the first integrator 311 and the second integrator 312 of the calculation unit 300. Therefore, the propagation time t_a, T_bThe calculation of the length measurement can be easily performed without using the sound velocity V at which the ultrasonic wave propagates in the magnetostrictive delay line 210, which is a factor affected by the temperature change.
[0051]
Further, by forming the magnetostrictive delay line 210 with a low expansion material having a magnetostrictive property or a composite material of a low expansion material and a magnetostrictive metal, measurement is performed by a change in the length of the magnetostrictive delay line due to a temperature change. Length errors can be easily suppressed, and more accurate length measurement can be easily performed.
[0052]
Further, by providing a temperature adjusting means such as a heat pipe (not shown) on the magnetostrictive delay line 210, an error in the measured length due to a dimensional change in the length direction of the magnetostrictive delay line 210 due to a temperature change can be easily suppressed. Accurate length measurement can be easily performed.
[0053]
[Second embodiment]
Next, another embodiment of the length measuring device of the present invention will be described with reference to the drawings. The length measuring device according to the second embodiment differs from the length measuring device according to the first embodiment in that the length measuring device measures the propagation time. FIG. 3 is a schematic diagram illustrating a schematic configuration of the length measuring device according to the second embodiment. In addition, about the same structure as 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.
[0054]
In FIG. 3, reference numeral 400 denotes a length measuring device. The length measuring device 400 includes a measuring unit 200 similar to that of the first embodiment, and an arithmetic unit 500 as arithmetic means.
[0055]
The calculation unit 500 includes an oscillator 510, a counter 520, a calculation unit 330, and a display unit 340. Further, the counter 520 includes a first counter 521 connected to the first winding 242A of the first detection unit 242, and a second counter 521 connected to the second winding 243A of the second detection unit 243. And a counter 522.
[0056]
Oscillator 510 generates a reference frequency. Then, the first counter 521 supplies the pulse current to the magnetostrictive delay line 210 by the pulse current generating means 220 and generates the ultrasonic waves by the ultrasonic generating magnetic body 230, and then the first winding 242A. Propagation time t to read voltage pulse generated at_aIs measured based on the reference frequency generated from the oscillator 510. Similarly, the second counter 522 supplies a pulse current to generate an ultrasonic wave and then reads a propagation time t between reading a voltage pulse generated in the second winding 243A._bIs measured based on the reference frequency generated from the oscillator 510. Then, the arithmetic unit 500 calculates the propagation time t acquired by the first counter 521 and the second counter 522._a, T_bBased on the distance l between the first winding 242A and the second winding 243A acquired and set in advance by measurement, the first magnetic material 230 from the ultrasonic wave generating magnetic body 230 is calculated by the above-described Expression 2. The distance x to the winding 242A is calculated and displayed on the screen by the display means 340.
[0057]
In the second embodiment shown in FIG. 3, the pulse current supplied to the magnetostrictive delay line 210 by the pulse current generating means 220 based on the reference frequency of the oscillator 510 by the first counter 521 and the second counter 522. From when the ultrasonic wave is generated by the ultrasonic wave generating magnetic body 230 until the first detecting unit 242 and the second detecting unit 243 generate the voltage pulse by the ultrasonic wave propagating through the magnetostrictive delay line 210. Measure the time and the propagation time t_a, T_bTo get. Then, the obtained propagation time t_a, T_bThe distance x from the ultrasonic generating magnetic body 230 to the first winding 242A is calculated by the calculation unit 330, and the length is measured. For this reason, similarly to the first embodiment, the first detecting unit 242 and the second detecting unit 243 provided with the interval so as not to be changed have the ultrasonic generating magnetic body 230 for generating the ultrasonic wave. Ultrasonic waves can be easily generated without affecting the relative movement with respect to the magnetostrictive delay line 210, and the distance between a pair of the first and second detectors 242 and 243 provided side by side can be changed, for example, by a temperature change. Even if such a situation occurs, it can be supported by the low-thermal-expansion support 241 which is arranged so as not to fluctuate, and high-precision length measurement can be easily performed with the simple configuration.
[0058]
Further, in the second embodiment, in addition to the operation and effect of the first embodiment, the first counter 521 and the second counter 522 control the ultrasonic wave based on the reference frequency generated from the oscillator 510. The time from the generation to the generation of the voltage pulse by the ultrasonic wave is measured by the pair of the first detection unit 242 and the second detection unit 243, and the propagation time t_a, T_bTo get. Therefore, the propagation time t_a, T_bCan be easily obtained, and the obtained propagation time t_a, T_bThe calculation of the length measurement can be easily performed without using the sound speed V at which the ultrasonic wave propagates in the magnetostrictive delay line 210 which is a factor such as the sound speed V affected by the temperature change.
[0059]
[Third Embodiment]
Next, still another embodiment of the length measuring device of the present invention will be described with reference to the drawings. The length measuring device according to the third embodiment obtains the propagation time by one detecting unit as the internal length reference means in the first and second embodiments. FIG. 4 is a schematic diagram illustrating a schematic configuration of a length measuring device according to the third embodiment. In addition, about the same structure as 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.
[0060]
In FIG. 4, reference numeral 600 denotes a length measuring device, and the length measuring device 600 includes a measuring section 700 and an arithmetic section 800 as arithmetic means. The measuring unit 700 includes a magnetostrictive delay line 210, a pulse current generating unit 220, a magnetic body 230 for generating ultrasonic waves, and an internal length reference unit 710. The arithmetic unit 800 includes a separating circuit 810, an integrating unit 310, a converter 320, a calculating unit 330, and a display unit 340.
[0061]
The internal length reference means 710 of the measuring section 700 includes a detecting section 711 as detecting means. The detection unit 711 includes a winding 711A and a bias magnetic body 711B. The winding 711A is wound around one end in the longitudinal direction of the magnetostrictive delay line 210 at a position at a predetermined distance 1 from one end of the magnetostrictive delay line 210, and is connected to the arithmetic unit 800 to output an electric signal to the arithmetic unit 800. . The biasing magnetic body 711B is arranged close to the winding 711A, and generates a bias magnetic field in the magnetostrictive delay line 210. The detecting unit 711 generates a voltage pulse in the winding 711A by the magnetostriction effect of the ultrasonic wave, because the bias magnetic field is applied by the bias magnetic body 711B and the magnetic flux changes, and the generated voltage pulse is generated. Is output to the arithmetic unit 800. The generated voltage pulse is generated by the first ultrasonic wave propagating through the magnetostrictive delay line 210 and is also generated by the reflected wave that is reflected by the ultrasonic wave that has once reached one end of the magnetostrictive delay line 210.
[0062]
In addition, the separation circuit of the arithmetic unit 800 determines the first voltage pulse generated by the ultrasonic wave that propagates first and the second voltage pulse generated by the reflected ultrasonic wave as the voltage pulse generated by the ultrasonic wave in the detection unit 711. And separate. The separated first voltage pulse and second voltage pulse are output to integrator 310.
[0063]
Then, the first integrator 311 of the arithmetic unit 800 calculates the propagation time t from when the pulse current is supplied by the pulse current generating means 220 to when the first voltage pulse is read._aIs calculated by time integration. Further, the second integrator 312 of the arithmetic unit 800 calculates the propagation time t from the supply of the pulse current to the reading of the second voltage pulse._bIs calculated by time integration. Then, the calculation unit 330 calculates the propagation time t._a, T_bThe distance x from the ultrasonic wave generating magnetic body 230 to the detection unit 711 is calculated by the above equation 2 based on the distance l from one end of the magnetostrictive delay line 210 to the winding 711A. Note that the propagation time t_bIs the time for the ultrasonic wave to reciprocate over the distance l, so that the propagation time t_bThe distance x is calculated using Equation 2 by, for example, using half the time or a value obtained by doubling the distance l.
[0064]
In the third embodiment shown in FIG. 4, a pulse current generating means 220 supplies the magnetostrictive delay line 210 to the magnetostrictive delay line 210 at a detection unit 711 provided at a predetermined position, for example, a distance l from one end of the magnetostrictive delay line 210. The first voltage pulse is generated by the ultrasonic wave generated by the ultrasonic generating magnetic body 230 with the pulse current, and the ultrasonic wave generated by the ultrasonic generating magnetic body 230 is reflected at one end of the magnetostrictive delay line. A second voltage pulse is generated by the reflected wave. Then, a propagation time t from when the pulse current is supplied to when the first voltage pulse is generated._aAnd a propagation time t from supply of the pulse current to generation of the second voltage pulse._bIs calculated by time integration in the integrator 310 as in the first embodiment, and the distance x from the magnetic body 230 for ultrasonic wave generation to the detector 710 is calculated by the calculator 330 using Equation (2). Is calculated and the length is measured. For this reason, similarly to the first embodiment, the first detecting unit 242 and the second detecting unit 243 provided with the interval so as not to be changed have the ultrasonic generating magnetic body 230 for generating the ultrasonic wave. Ultrasonic waves can be easily generated without affecting the relative movement with respect to the magnetostrictive delay line 210, and the distance between a pair of the first and second detectors 242 and 243 provided side by side can be changed, for example, by a temperature change. Even if such a situation occurs, it can be supported by the low-thermal-expansion support 241 which is arranged so as not to fluctuate, and high-precision length measurement can be easily performed with the simple configuration.
[0065]
Further, in the third embodiment, in addition to the effects of the first embodiment, the configuration of the measuring section 700 can be simplified since the internal length reference means 710 is constituted by one detecting section 711. .
[0066]
[Other embodiments]
It should be noted that the length measuring device of the present invention is not limited to each of the above-described embodiments, and it goes without saying that various changes can be made without departing from the spirit of the present invention.
[0067]
That is, as described above, the magnetostrictive delay line 210 may be provided with a temperature adjusting unit, or may be configured so as not to include the temperature adjusting unit in an environment where there is no temperature change. Further, it is preferable that the magnetostrictive delay line 210 be formed of a material whose length dimension does not fluctuate due to a temperature change. It may be formed only.
[0068]
In addition, the specific structure and procedure for implementing the present invention may be changed to another configuration as long as the object of the present invention can be achieved.
[0069]
【The invention's effect】
According to the present invention, an ultrasonic wave generated and propagated in the magnetostrictive delay line is detected by a pair of detecting means provided at one end of the magnetostrictive delay line so that the interval is not variable, and the ultrasonic wave is calculated by the calculating means. Since the distance from the generated position to the detecting means is calculated and the length is measured, the operation of generating ultrasonic waves in the magnetostrictive delay line by the detecting means provided with the interval invariable is not affected, The configuration in which the distance between the pair of detecting means provided is not changed even when a temperature change or the like occurs can be simplified, and highly accurate length measurement can be easily performed with a simple configuration.
[0070]
Further, according to the present invention, the ultrasonic wave generated and propagated in the magnetostrictive delay line is detected by the detecting means provided at a predetermined position from one end in the longitudinal direction of the magnetostrictive delay line, and from the generation of the ultrasonic wave to the detection. To calculate the distance from the position where the ultrasonic wave is generated to the detecting means based on the propagation time of the ultrasonic wave and the propagation time from the generation of the ultrasonic wave to the detection of the ultrasonic wave reflected at one end of the magnetostrictive delay line, one end of the magnetostrictive delay line is calculated. The operation of generating ultrasonic waves in the magnetostrictive delay line by the detection means provided at a predetermined position is not affected, and even if a temperature change or the like occurs due to forming the magnetostrictive delay line with a low expansion material, for example. A configuration in which the propagation time does not fluctuate due to a temperature change can be easily obtained, and highly accurate length measurement can be easily performed with a simple configuration.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of an embodiment of a length measuring device according to the present invention.
FIG. 2 is a timing chart illustrating an operation for calculating a distance x between a position of a magnetic body for generating ultrasonic waves and a first winding according to the embodiment.
(A): Waveform diagram of pulse current supplied by pulse current generating means
(B): Waveform diagram of the voltage pulse generated in the first winding
(C): Waveform diagram of voltage pulse generated in second winding
(D): graph of time integration by first integrator
(E): graph of time integration by the second integrator
FIG. 3 is a block diagram showing a schematic configuration of another embodiment of the length measuring device of the present invention.
FIG. 4 is a block diagram showing a schematic configuration of still another embodiment of the length measuring device of the present invention.
FIG. 5 is a diagram showing a conventional length measuring device.
(A): block diagram showing a schematic configuration of a length measuring device
(B): Voltage pulse V applied to the primary coil of transformer CT1_iWaveform diagram of
(C): First detection coil N₁Diagram of voltage pulse generated in
(D): First detection coil N_TwoDiagram of voltage pulse generated in
[Explanation of symbols]
100,400,600 Length measuring device
210 Magnetostrictive delay line
220 Pulse current generating means constituting ultrasonic generating means
230 Ultrasonic wave generating magnetic material constituting ultrasonic wave generating means
242 First detection unit as detection means
243 Second detection unit as detection means
300, 500, 800 Arithmetic unit as arithmetic means
510 oscillator
520 counter
711 Detecting unit as detecting means

Claims (7)

A longitudinal magnetostrictive delay line,
Ultrasonic wave generating means for generating ultrasonic waves on the magnetostrictive delay line,
A pair of detecting means for detecting ultrasonic waves propagating through the magnetostrictive delay line, each of which is provided with an interval at one end in the longitudinal direction of the magnetostrictive delay line so as not to fluctuate,
A calculating means for calculating a distance from the position where the ultrasonic wave is generated to the magnetostrictive delay line by the ultrasonic wave generating means to the detecting means,
A length measuring device characterized by comprising: The length measuring device according to claim 1,
The calculating means calculates a distance based on a propagation time from generation of an ultrasonic wave by the ultrasonic wave generating means to detection of an ultrasonic wave by the pair of detecting means, and a distance between the pair of the detecting means. Characteristic length measuring device. The length measuring device according to claim 2,
The length measuring device is characterized in that the calculating means calculates a propagation time from generation of the ultrasonic wave by the ultrasonic wave generating means to detection of the ultrasonic wave by the pair of detecting means by time integration. The length measuring device according to claim 2,
The arithmetic unit includes an oscillator that generates a reference frequency, and a counter that measures a propagation time from generation of the ultrasonic wave to detection of the ultrasonic wave by the pair of detection units based on the reference frequency from the oscillator. A length measuring device characterized in that: A longitudinal magnetostrictive delay line,
Ultrasonic wave generating means for generating ultrasonic waves on the magnetostrictive delay line,
Detecting means provided at a predetermined position from one end of the magnetostrictive delay line at one end in the longitudinal direction of the magnetostrictive delay line and detecting ultrasonic waves propagating through the magnetostrictive delay line,
The distance from the position where the ultrasonic wave is generated to the magnetostrictive delay line by the ultrasonic wave generating means to the detecting means, from the propagation time from the generation of the ultrasonic wave to the detection of the ultrasonic wave by the detecting means and the generation of the ultrasonic wave A calculating means for calculating based on the propagation time until the detection of the ultrasonic wave reflected at one end of the magnetostrictive delay line,
A length measuring device characterized by comprising: The length measuring device according to any one of claims 1 to 5,
The length measuring device, wherein the magnetostrictive delay line is formed of a low expansion material having a magnetostrictive characteristic or a composite material of a low expansion material and a magnetostrictive metal. The length measuring device according to any one of claims 1 to 6,
The length measuring device, wherein the magnetostrictive delay line has a temperature adjusting unit.

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