JPH0574003B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a displacement calculation element, and in particular, to a displacement calculation element, in which two conductor coils are connected in series to a magnetic member, two metal conductor shields spatially overlap each other, and a magnetic The present invention relates to a displacement calculation element that detects the sum, difference, and product of two minute displacements with respect to a body member (conductor coil).

[Conventional technology]

In numerically controlled machine tools, etc., it is an extremely important technology to accurately detect the displacement of an object. Conventionally, the following techniques are widely known as techniques for detecting the displacement of an object. That is, a method of converting the amount of displacement into an electrical resistance value via a potentiometer, a method of using a strain gauge, a method of using a Magnescale using the Hall effect or magnetoresistive effect, a method of using an optical encoder, and a method of reflecting laser light. These include optical interferometry, which uses ultrasonic reflection and its phase shift, and ultrasonic interferometry, which utilizes ultrasonic reflection and its phase shift.

To detect displacement with a potentiometer,
It is necessary to bring the electric resistor and the position detection electrode into contact and to slide them against each other. In this method, contact sliding of the electrodes is essential.

A strain gauge detects the amount of strain based on a change in electrical resistance value when the length of an electrical resistance wire changes. Therefore, in order to detect the displacement of an object, it is necessary to connect the object and the reference position using this strain gauge.

Magnescale is a linear high-coercivity magnetic material that is regularly magnetized in the normal and reverse directions along its length. A magnetic field sensor using the Hall effect or magnetoresistive effect is provided near this magnetescale. The magnetic field sensor is moved along the magnet scale, and the amount of movement, that is, the displacement of the magnetic field sensor is calculated using the number of changes in the magnetic field detected by the magnetic field sensor.

Displacement detection using an optical encoder also uses a scale with a complex optical pattern similar to Magnescale.
Calculate displacement from changes in light intensity.

Displacement measurement using optical interferometry or ultrasonic interferometry involves irradiating an object with light or ultrasonic waves emitted from a light source or sound wave source, detecting the phase of the light or ultrasonic waves reflected from the object, and measuring the movement of the object. The displacement is calculated by detecting the change in phase associated with the change in phase.

In addition, when calculating the sum, difference, product, etc. using two displacement amounts, it is necessary to calculate the displacement using these displacement measurement means and then calculate it again using a calculation means or an arithmetic circuit. It was hot.

[Problem that the invention seeks to solve]

The conventional displacement detection techniques described above each have the following drawbacks.

That is, in the technology of detecting displacement using a potentiometer, since contact and sliding of the phase detection electrode is essential, there are problems with durability and reliability due to wear.

The technique of detecting displacement with a strain gauge has the disadvantage that repeated use causes plastic deformation of the electrical resistance wire, lacks reliability, and furthermore makes it difficult to measure displacement in the compression direction.

The technology to detect displacement using Magnescale is
It has the disadvantage that it not only requires a complicated structure but also requires expensive calculation means.

The technique of detecting displacement using an optical encoder has the disadvantage that, like the Magnescale, it requires a scale with a complicated optical pattern and a complicated circuit for calculating displacement from changes in light intensity.

Technologies that detect displacement using optical interferometry or ultrasonic interferometry require expensive light and sound sources, as well as high-precision phase detectors and high-performance calculation means to calculate displacement from detected phase changes. There is a drawback that it is melty.

Furthermore, when measuring the sum, difference, product, etc. using two displacement amounts, there is a drawback that it is necessary to calculate the displacement again after calculating the displacement with each of the above-mentioned displacement measuring means.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and to provide a displacement calculation element that is easy to measure and can calculate the difference, sum, and product of displacement amounts with a simple and inexpensive configuration and with high reliability.

[Means for solving problems]

In the displacement calculation element of the present invention, first, second, and third conductor coils are respectively arranged at three locations apart from each other on a rod-shaped soft magnetic body, and the first conductor coil is disposed between the second and third conductor coils. is provided so that an alternating current is applied to the first conductor coil, and the second conductor coil and the third conductor coil are connected magnetically in opposite directions and electrically in series. and a structure in which first and second metal conductor shields are provided around the second and third conductor coils, respectively, so that the overlapping length of the conductor coil and the metal conductor shield can be independently varied, Alternatively, the first, second, and third conductor coils are respectively placed at three locations apart from each other on the rod-shaped soft magnetic material, and the first, second, and third conductor coils are disposed between the second and third conductor coils.
A conductor coil is provided so that an alternating current is applied to the first conductor coil, and the second conductor coil and the third conductor coil are magnetically in the same direction and electrically in series. First and second metal conductor shields are provided around the second and third conductor coils, respectively, so that the overlapping length of the conductor coil and the metal conductor shield can be independently varied. The structure or the rod-shaped soft magnetic material has two first parts located apart from each other.
and a second conductor coil, and the first conductor coil.
An alternating current is applied to either one of the first and second conductor coils, a metal conductor shield is arranged around the first and second coils, and the overlapping length of the coil and the conductor shield is Each of them is constructed with a structure that can be independently varied.

[Effect]

The invention operates on the following principles. That is, an excitation coil is attached to a part of the rod-shaped soft magnetic material and an alternating current is applied thereto. When a magnetic flux detection coil is provided at one end of a bar-shaped soft magnetic material separated from the excitation coil, a voltage proportional to the frequency and amplitude of the excitation current is generated in the detection coil due to electromagnetic induction. A shield made of a material with high electrical conductivity is provided so as to spatially surround this magnetic flux detection coil. A magnetic field generated from one end of the rod-shaped soft magnetic material generates an eddy current in the conductive shield, and this eddy current creates a reverse magnetic field in the magnetic material. Therefore, substantially no magnetic flux exists in the shielded magnetic material portion. In other words, there is substantially no magnetic flux in the overlapping region of the shield and the magnetic flux detection coil, and the induced voltage generated in the magnetic flux detection coil decreases in proportion to the magnitude of the overlap. The magnitude of this overlap thus corresponds to the displacement. The conductor shield and the magnetic flux detection coil do not need to be in contact with each other, and by using this principle, a non-contact displacement sensor can be realized. Furthermore, by providing shields at both ends of the magnetic body, calculation of two displacement amounts becomes possible.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1A is a block diagram of a first embodiment of the displacement calculation element of the present invention, and FIG. 1B is an output characteristic diagram of the detection coil of the embodiment of FIG. 1A. The first shown in Figure 1A
In the embodiment, a soft magnetic material pattern 1 as a rod-shaped soft magnetic material is electrically connected in series near both ends of the soft magnetic material pattern 1, and magnetically the winding directions are reversed to have opposite characteristics. a pair of detection coils 3 and 5 arranged at
and a pair of conductor shield patterns 4 and 5 arranged concentrically so as to spatially overlap with the detection coils 3 and 5 in a non-contact state. If the overlapping length between the conductor shield pattern 4 and the detection coil 3 is x ₁ and the overlapping length between the conductor shield pattern 6 and the detection coil 5 is x ₂ , then the output of the detection coils 3 and 5 alone is the overlap length. They are proportional to x1 and x2, and their polarities are opposite to each other. The combined output of both coils is proportional to (x ₁ -x ₂ ) as shown in FIG. 1B. That is, this embodiment provides an arithmetic element that can easily determine the difference between two displacement amounts without using any special arithmetic circuit.

FIG. 2A is a block diagram of a second embodiment of the displacement calculation element of the present invention. As shown in FIG. 2A, a soft magnetic material pattern 1, an excitation coil 2, a detection coil 3,
5, alternating current source 20 and conductor shield pattern 4,
6 is almost the same as in FIG. 1A. The difference is that the winding direction of the detection coil is opposite to that in FIG. 1A and is wound in the same direction. The overlapping length of conductor shield pattern 4 and detection coil 3 is
x ₁ , and the overlapping length between the conductor shield pattern 6 and the detection coil 5 is x ₂ , the output of the detection coils 3 and 5 alone is -x ₁ , as can be easily seen from the embodiment shown in FIG. 1A. and −x is proportional to ₂ . Therefore, the combined output of both coils is (x ₁
+x ₂ ). That is, this embodiment provides an arithmetic element that can easily calculate the sum of two displacement amounts without using any special arithmetic circuit.

FIG. 3 is a configuration diagram of a third embodiment of the displacement calculation element of the present invention. The displacement calculation element shown in Fig. 3 is
The same soft magnetic material pattern 1 as in FIG. 1, a detection coil 3 as a first conductor coil, an excitation coil 2 as a second conductor coil, and first and second conductor shield patterns 4 and 6. In addition, an alternating current source 20 is also shown. The overlapping length of conductor shield 4 and detection coil 3 is x ₁ , conductor shield pattern 6
When the overlapping length between the excitation coil 2 and the excitation coil ₂ is x2, the magnetic flux generated from the excitation coil decreases in proportion to _x2 . The detection coil 3 detects the magnetic flux proportional to x ₂ , but at this time the detection output decreases in proportion to x ₁ . That is, this detection output is proportional to x ₁ x ₂ as a result. In other words, in this example,
The present invention provides an arithmetic element that easily calculates the product of two displacement amounts without using any special arithmetic circuit.

Note that in the third embodiment shown in FIG. 3, the alternating power supply is applied to the excitation coil 2, which is the second detection coil, but it can also be applied to the detection coil 3 in the same way. is clear.

〔Effect of the invention〕

As described above, according to the present invention, detection coils are arranged at both ends of a rod-shaped magnetic member, conductor shields are arranged that spatially overlap these detection coils, and a dedicated excitation coil or any detection coil is arranged. By using an excitation coil that uses AC excitation, it is possible to easily calculate the sum, difference, and product of the displacement of two detection coils with respect to a rod-shaped magnetic member, ensuring high sensitivity and high reliability without the need for a special calculation circuit. It has the desired effect.

[Brief explanation of the drawing]

Fig. 1A is a block diagram of the first embodiment of the present invention, Fig. 1B is an output characteristic diagram of the detection coil of Fig. 1A, and Fig. 2A is a block diagram of the second embodiment of the present invention. , FIG. 2B is an output characteristic diagram of the detection coil of FIG. 2A, and FIG. 3 is a configuration diagram of a third embodiment of the present invention. 1... Soft magnetic material pattern, 2... Excitation coil,
3, 5...detection coil, 4, 6...conductor shield pattern, 20...alternating current source.

Claims (1)

[Scope of Claims] 1. First, second, and third conductor coils are respectively placed at three locations apart from each other on a rod-shaped soft magnetic body, and the first conductor coil is disposed between the second and third conductor coils. An alternating current is applied to the first conductor coil, and the second conductor coil and the third conductor coil are magnetically connected in opposite directions and electrically connected in series. At the same time, there are first conductor coils around the second and third conductor coils, respectively.
and a second metal conductor shield having a structure in which spatial overlapping lengths of the second and third conductor coils and the first and second metal conductor shields can be independently varied, Spatial overlap length x1 between the first metal conductor shield and the second conductor coil and spatial overlap length x2 between the second metal conductor shield and the third conductor coil
The output corresponding to the difference (x1 - x2) between both ends of the second conductor coil and the third conductor coil is calculated as the difference in displacement of the first and second metal conductor shields with respect to the rod-shaped soft magnetic body. A displacement calculation element characterized by outputting. 2. First, second, and third conductor coils are provided at three mutually distant locations of the rod-shaped soft magnetic material such that the first conductor coil is interposed between the second and third conductor coils. Furthermore, an alternating current is applied to the first conductor coil, and the second and third conductor coils are connected magnetically in the same direction and electrically in series, and Each of the first conductor coils is placed around the third conductor coil.
and a structure in which a second metal conductor shield is provided so that the spatial overlapping lengths of the second and third conductor coils and the first and second metal conductor shields can be varied independently, a spatial overlap length x1 between the first metal conductor shield and the second conductor coil; and a spatial overlap length x1 between the second metal conductor shield and the third conductor coil.
The output corresponding to the sum (x1+x2) of A displacement calculation element characterized by output. 3. First and second conductor coils are provided at two mutually apart locations of the rod-shaped soft magnetic material, and an alternating current is applied using one of the first and second conductor coils as an excitation coil, so that the first and second conductor coils are First and second metal conductor shields are arranged around the vicinity of the second coil, respectively, and the spatial overlapping length between the first and second conductor coils and the first and second conductor shields is determined. a spatial overlap length x1 between the first metal conductor shield and the first conductor coil, and a spatial overlap length x1 between the second metal conductor shield and the third conductor coil; The output corresponding to the product (x1 x A displacement calculation element characterized in that an output is output between both ends of the excitation coil of the conductor coil and the other conductor coil.