JP2008116236A - Method and device for measuring resistance in strong magnetic field - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the measurement from being affected by the induced voltage between the signal lines connecting the probe and the resistance measurement circuit by improving the resistance measurement technique in the strong magnetic field. <P>SOLUTION: The probe 2 is in contact with a work 1 of a measurement object, sends signal to a resistance measurement circuit 6, and measures the electric resistance of the work. A magnet 7 moves parallel in X-axis direction for changing the magnetic field intensity impressed on the work 1, and rotates around the X-axis by 180° for inverting the direction of the magnetic field impressed on the objective work 1. For making an A signal line 4 or a B signal line 5 generate no induced voltage, even if the magnet 7 moves in the X-axis direction, the signal lines are oppositely faced in the Z-axis direction (i.e. in the magnetic field direction) while being separated. Because of no magnetic field line passing through between the two signal lines 4 and 5, even the magnet 7 moves between the arrow marks a to c, no induced voltage is generated. Moreover, an arm 10 is constituted of a resin material, no eddy current is induced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to measurement of resistance in a strong magnetic field used for inspection of a magnetic head and the like, and prevents occurrence of measurement errors with a simple and inexpensive configuration.

FIG. 3 is a schematic diagram illustrating a conventional apparatus for measuring resistance in a strong magnetic field.
The two workpieces 2 are brought into contact with the workpiece 1 to be measured and the resistance measurement circuit 6 measures the resistance value via the two signal lines (A signal line 4 and B signal line 5). The direction and intensity of the magnetic field applied to 1 are changed.
Although not shown in the drawings, there are also conventional examples in which resistance measuring circuits are connected to a plurality of pairs of probes via a plurality of pairs of signal lines. For convenience of explanation, a conventional example in which one pair (two) of probes is connected to one pair (two) of signal lines will be described below. In the case of a plurality of pairs, one pair (two) of them is the same as one pair (two) described below.
The pair of (two) probes 2 are mounted on a substrate 3, and the substrate 3 is supported by a brass arm 8.

Although two magnets are depicted in this figure, the number of magnets installed is one, and guide / drive means (not shown) is provided so as to reciprocate in the directions of arrows ac.
Reference numeral 7A indicates a magnet at the forward position, and reference numeral 7B indicates a magnet at the reverse position. Reference numerals N and S added to the magnet represent magnetic poles and polarities, and those added with phantom lines represent a magnetic yoke. The actual yoke is annular, but is drawn in a U shape for the sake of simplicity.

For convenience of explanation, a Z-axis parallel to the magnetic field is assumed, the magnetic field direction is Z ′, and the opposite direction is Z.
The direction of the two signal lines is orthogonal to the Z axis, and this direction is taken as the X axis.
Next, a state in which the intensity and direction of the magnetic field applied to the workpiece 1 to be measured will be described with reference to FIG.

The first step magnet is set to the forward position 7A. As a result, the magnetic field strength in the Z ′ direction given to the workpiece 1 to be measured becomes the maximum value +1.5 (T).
The magnet 7A in the second process advance position is translated in the direction of arrow a to the retreat position 7B. Thereby, the magnetic field intensity given to the workpiece 1 to be measured decreases to the minimum value 0 (T).
The magnet 7B in the third process retreat position is rotated 180 degrees around the X axis as indicated by an arc arrow b. In this step, the magnetic field strength applied to the workpiece 1 to be measured does not change any more (because the magnetic field strength is 0).
Fourth Step The magnet 7B in the reverse position is translated to the forward position 7A as indicated by an arrow c. Thereby, the magnetic field intensity given to the workpiece 1 to be measured increases to the maximum value −1.5 (T) in the opposite direction.
5th step Operate in the same way as the 2nd step (arrow a movement), weaken the magnetic field strength to 0 (T),
The sixth step, similar to the third step (rotating the arc d), reverses the magnetic pole direction,
Seventh Step The magnet 7B in the reverse position is translated (arrow c) to the forward position 7A as indicated by the arrow c. Thereby, the magnetic field strength given to the workpiece 1 to be measured increases to a positive maximum value +1.5 (T).

Regarding a technique for measuring electric resistance by applying a magnetic field, a sheet resistance measuring method described in Japanese Patent Laid-Open No. 2001-31750 shown in Patent Document 1 is known. An eddy current is generated, eddy current loss is measured to calculate a resistance value, and this is a technique in a field different from the present invention.
JP 2001-31750 A

In the second step, the fourth step, the fifth step, and the seventh step in the resistance value measuring operation described above, that is, when the magnet is translated in the X-axis direction, the following problems occur.
I. Since the magnetic lines of force move in the loop formed by the two signal lines (4, 5) and the probe 2, a minute induced voltage is generated. Although the voltage value is extremely small, the measurement of resistance in the strong magnetic field requires extremely high accuracy, and thus the error due to the induced voltage cannot be ignored.
B. Since the magnetic lines of force move in the arm 8 made of a conductive material, an induced eddy current is generated to move the arm 8.
When the arm 8 moves, the probe 2 is moved and slides with respect to the workpiece 1 to be measured, so that a measurement error occurs.

The present invention has been made in view of the circumstances described above, and its purpose is as follows.
It is an object of the present invention to provide a technique for measuring resistance in a strong magnetic field that does not generate an induced voltage in a signal line even when a magnet is moved in parallel with the signal line, and does not cause an eddy current in an arm.

The basic principle of the present invention created in order to achieve the above object is briefly described as follows.
I. In order to prevent an induced voltage from being generated in the signal line, a magnetic field line is prevented from passing through a loop formed by the signal line. That is, the loop formed by the signal lines is positioned in a plane parallel to the magnetic field lines.
B. In order to prevent an eddy current from being generated in the arm, the arm is made of an electrically insulating material.

The method for measuring resistance in a strong magnetic field according to the invention of claim 1 comprises:
While making the probe connected to the tip of one or more pairs of parallel signal wires contact and conduct to the workpiece to be measured and measuring the resistance value, the workpiece to be measured is positioned in the magnetic field of the magnet,
Strong magnetic field resistance that moves the magnet parallel to the signal line to change the magnetic field strength applied to the workpiece to be measured, or rotates the magnet to reverse the direction of the magnetic field applied to the workpiece to be measured. In the measurement method,
The longitudinal direction of the one or more pairs of parallel signal lines is the X axis, and the direction in which the magnetic poles of the magnet are facing is the Z axis,
The magnetic field lines are prevented from passing through a loop formed by the one or more pairs of signal lines by arranging the one or more pairs of signal lines so as to face each other in the Z-axis direction. And

The strong magnetic field resistance measurement method according to the invention of claim 2 includes, in addition to the constituent features of the invention method of claim 1,
By supporting the one or more pairs of signal lines using an arm made of an electrically insulating non-magnetic material, it is possible to prevent the generation of induced eddy currents in the signal line supporting member as the magnet moves. And

The configuration of the strong magnetic field resistance measurement apparatus according to the invention of claim 3 is:
A probe connected to the tip of one or more pairs of parallel signal lines;
A magnet that applies a magnetic field in the Z-axis direction to a workpiece to be measured at a position to receive contact of the probe;
Means for moving the magnet in the X-axis direction parallel to the signal line;
In a strong magnetic field resistance measurement device having means for reversing the magnetic field direction of the magnet,
One or a plurality of pairs of signal lines in the X-axis direction are arranged to be opposed to and separated from each other in the Z-axis direction.

The configuration of the strong magnetic field resistance measurement device according to the invention of claim 4 is in addition to the configuration requirements of the invention of claim 3,
The one or more pairs of signal lines are formed by a conductive pattern of a substrate.

The configuration of the strong magnetic field resistance measurement device according to the invention of claim 5 is in addition to the configuration requirements of the invention of claim 4,
The substrate on which the one or more pairs of signal lines are formed is supported by an arm made of an electrically insulating nonmagnetic material.

When the inventive method of claim 1 is applied, one or more pairs of signal lines oppose each other in the direction of the magnetic field, so that magnetic lines of force do not pass through the loop formed by the one or more pairs of signal lines.
Therefore, even if the magnetic field applied to the workpiece to be measured is changed by moving the magnet, an induced voltage is not generated in the signal line forming the loop. High precision measurement can be performed at double speed.

When the inventive method of claim 2 is applied together with the inventive method of claim 1,
Since the arm for supporting the signal line is made of an electrically insulating material, no eddy current is induced even if the magnetic lines move in the arm. Therefore, the arm is not moved by electromagnetic force, the probe supported on the arm is kept stationary, and there is no possibility that high-precision measurement of the electric resistance value is hindered.

When the apparatus for measuring resistance in a strong magnetic field according to claim 3 is applied, one or more pairs of signal lines are arranged facing the Z-axis direction, that is, the magnetic field direction. Magnetic field lines do not pass through the loop formed by Therefore, even if the magnetic lines of force move, no induced voltage is generated in the signal line, and the resistance value can be measured with high accuracy.
Since adverse effects due to induction could be prevented, measurement could be performed at a speed several times that of the conventional example.

When the strong magnetic field resistance measurement device according to claim 4 is applied together with the invention of claim 3,
Since one or more pairs of signal lines are configured by a conductive pattern on the substrate, the one or more pairs of signal lines are configured with high accuracy at low cost, and the mutual positional relationship is reliably maintained. .
In addition, the magnetic pole spacing of the magnet can be reduced by reducing the thickness of the substrate. Due to the reduction of the magnetic pole spacing, the magnetic resistance is reduced and a strong applied magnetic field can be obtained.

When the strong magnetic field resistance measurement device according to claim 5 is applied together with the invention of claim 4,
Since the arm supporting the substrate is made of a non-magnetic material, no eddy current is induced in the arm even if the magnetic field lines move relative to the arm.
Therefore, there is no possibility that the arm is moved by electromagnetic force. Since the arm is not moved, the supported probe is stably held, and the electric resistance can be measured with high accuracy.

FIG. 1 is a schematic diagram showing an embodiment of the apparatus for measuring resistance in a strong magnetic field according to the present invention, with a partially enlarged sectional view appended thereto.
In this figure, in order to express the present invention simply, a pair (two) of probes and a pair (two) of signal lines are drawn, but a plurality of pairs (even numbers) of these members are arranged. In principle, this is the same as the case of one pair (two).
Reference numeral 7 denotes a magnet. Although not shown, as in the above-mentioned FIG. 3 (conventional example), there are provided means for reciprocally translating in the X-axis direction (arrows a-c) and means for rotating 180 degrees around the X-axis.
The workpiece 1 to be measured, the probe 2 and the resistance measurement circuit 6 are the same or similar members as in FIG. 3 (conventional example) described above.

The probe 2 of this embodiment is installed at one end of an elongated substrate 9 and supported by a resin arm 10.
The Z axis is the direction of the magnetic field of the magnet 7, and the X axis is the longitudinal direction of the substrate 9.
An enlarged cross section of the substrate 9 taken along the ZY plane is shown in the lower right part of FIG.
Two signal lines pass through the substrate 9. One of them is designated as the A signal line and designated by reference numeral 4, and the other is designated as the B signal line and designated by reference numeral 5.
When practicing the present invention, the material constituting the arm is not limited to resin. In short, a nonmagnetic electrically insulating material may be used.

The two signal lines are parallel to each other and arranged in the X direction,
The two signal lines 5A and 5B are opposed to each other in the Z direction.
Since the magnetic lines of force of the magnet 7 are in the Z-axis direction and the two signal lines are opposed to each other in the Z-axis direction, no magnetic lines of force pass between the two signal lines.
The two signal lines form a loop through the probe 2, but no magnetic lines pass through the loop, so that no induced voltage is generated in the signal lines even if the magnetic lines move.

The relationship between the two signal lines facing and separating in the Z-axis direction and the probe 2 will be described in detail with reference to FIG.
FIG. 2A is a schematic plan view of a conventional example shown for comparison. Compare this with Figure 3 above (conventional example).
FIG. 2B is a schematic plan view in the embodiment of the present invention, in which two signal lines (4, 5) overlap and are drawn in one. The perspective view is shown in FIG.
The A signal line 4 and the B signal line 5 are arranged side by side at the connection portion to the probe 2, but three-dimensionally twist and intersect in the immediate vicinity of the probe, and most of them are arranged vertically (Z axis direction). Yes.

Although it is not easy to hold a single signal line in the air as shown in FIG. 2C, in this embodiment, since it is formed in the substrate 9 as shown in FIG. Retained and protected from the outside.
Further, when the signal line is created as a conductive pattern of the substrate as in the present embodiment, the distance between the two signal lines can be reduced. As a result, the magnetic pole interval of the magnet 7 can be reduced.
When the magnetic pole interval is narrow, a strong magnetic field can be obtained because the magnetic resistance is small, and a strong magnetic field can be applied to the workpiece 1 to be measured.

(See FIG. 1) The arm 10 of this embodiment is made of resin. For this reason, even if the magnet 7 moves and the lines of magnetic force move, no eddy current is induced in the arm 10. Therefore, there is no possibility that the arm is moved by electromagnetic force.
When the arm is stationary, the substrate 9 supported by the arm is stable, and the probe 2 is stably held. For this reason, highly accurate resistance measurement becomes possible.
As described above, since adverse effects due to induction are prevented, in this embodiment, it is possible to perform high-accuracy measurement by moving the magnet several times faster than the conventional example, and the effect of improving efficiency is also obtained. It was.

The figure which added the partial expanded section to the schematic diagram which shows one Embodiment of the resistance measuring apparatus in a strong magnetic field which concerns on this invention (A) is the principal part top view of the prior art example shown for the comparison, (B) is the typical principal part top view in 1 embodiment of this invention, (C) is the model in 1 embodiment of this invention. Perspective view The figure which attached the arrow showing operation to the typical perspective view which drew the resistance measuring device in a strong magnetic field of the conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Work to be measured 2 ... Probe 3 ... Board 4 ... A signal line 5 ... B signal line 6 ... Resistance measurement circuit 7 ... Magnet 7A ... Magnet in forward position 7B ... Magnet in backward position 8 ... Arm 9 ... Board 10 ... Resin Arm

Claims (5)

While making the probe connected to the tip of one or more pairs of parallel signal wires contact and conduct to the workpiece to be measured and measuring the resistance value, the workpiece to be measured is positioned in the magnetic field of the magnet,
Strong magnetic field resistance that moves the magnet parallel to the signal line to change the magnetic field strength applied to the workpiece to be measured, or rotates the magnet to reverse the direction of the magnetic field applied to the workpiece to be measured. In the measurement method,
The longitudinal direction of the one or more pairs of parallel signal lines is the X axis, and the direction in which the magnetic poles of the magnet are facing is the Z axis,
By arranging the one or more pairs of parallel signal lines so as to face each other in the Z-axis direction, magnetic field lines do not pass through the loop formed by the one or more pairs of parallel signal lines. A method for measuring resistance in a strong magnetic field. By supporting the signal line using an arm made of an electrically insulating non-magnetic material,
The method for measuring resistance in a strong magnetic field according to claim 1, wherein generation of induced eddy current in the signal line support member is prevented with movement of the magnet. A probe connected to the tip of one or more pairs of parallel signal lines;
A magnet that applies a magnetic field in the Z-axis direction to a workpiece to be measured at a position to receive contact of the probe;
Means for moving the magnet in the X-axis direction parallel to the signal line;
In a strong magnetic field resistance measurement device having means for reversing the magnetic field direction of the magnet,
One or more pairs of parallel signal lines in the X-axis direction are opposed to and separated from each other in the Z-axis direction.   4. The apparatus for measuring resistance in a strong magnetic field according to claim 3, wherein the two signal lines are formed by a conductive pattern of a substrate.   5. The resistance measurement in a strong magnetic field according to claim 4, wherein the substrate on which the one or more pairs of parallel signal lines are formed is supported by an arm made of an electrically insulating nonmagnetic material. apparatus.

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