JPS63171026A - Magnetic encoder - Google Patents

Abstract

PURPOSE:To detect the extent of displacement of a magnetism shielding means with high resolution by the output of a magnetic detecting means, by providing the magnetic detecting means on a position facing a magnetic generating means and arranging a magnetism shielding means pierced with many slits between them. CONSTITUTION:A permanent magnet 27 and a magnetism detector 28 are provided to face each other, and a disk 26 which shields magnetism is arranged between them. Many slits 25 are provided on one and the same circle at a fixed angular pitch on the disk 26. The disk 26 is attached to a flange 22 formed together with a rotary shaft 21 integrally and is fixed by a clamping metal fitting 23. A magnetic field 29 passes slits 25 and is made incident on the detector 28. The passing magnetic field becomes a pulse train when the rotary shaft 21 is rotated, and this pulse train is detected by the detector 28, thereby obtaining a magnetic encoder which precisely measures the extent of displacement of the rotary shaft 21.

Description

[Detailed Description of the Invention] [Already Required] A magnetic encoder comprising a magnetic pulse train combined with a magnetic detection means, wherein the magnetic pulse train is a magnetic encoder formed by combining a magnetic generating means and a magnetic shielding material plate with a slit row. By configuring it with shielding means, a high-resolution magnetic encoder was realized.

[Industrial application field]

The present invention relates to a magnetic encoder used for detecting the position of a print head or the rotation angle of a rotating body, and particularly to a novel configuration for providing a high-resolution magnetic encoder.

[Conventional technology]

FIG. 4 is a perspective view showing an example of the main configuration of a conventional magnetic encoder.
1 includes a rotating body 13 in which a large number of magnetic patterns 12 are arranged in a ring shape so that the same polar surfaces are in contact with each other, and a magnetic detector 14 disposed above the rotating body 13.

In such a magnetic encoder 11, the rotating body 13 is attached to the rotating shaft of a motor, for example, and when the motor is driven, the rotating body 13 rotates, and the magnetic detector 1 fixed by an appropriate means is rotated.
4, the number of times the boundary of the magnetic pattern 12 has passed is counted by a detection circuit, and the rotation angle of the rotating shaft can be detected from the measured value.

[Problem that the invention seeks to solve]

A magnetic encoder that detects the amount of movement of a magnetic pulse train or a magnetic detector can detect the position and rotation angle of a moving object without being hindered by smoke or the like. However, in the conventional method, a magnetic material is coated on a non-magnetic material and a magnetic pattern is magnetized on the magnetic material, which is a manufacturing hassle. Shiha,
The production technology has a limit of about 40 .mu.m, and the desire to further improve the resolution and achieve higher precision has been hindered by the inability to reduce the length L of the magnetic pattern, which has been a problem.

[Means for solving problems]

FIG. 1 is a perspective view (A) showing an example of the basic configuration of the present invention, and a schematic diagram (+7) of its output characteristics.

In FIG. 1(A), a strip-shaped magnetic shielding means (magnetic shielding plate) 3 is arranged between the magnetic field generating means 1 and the magnetic shielding means 2, and the magnetic field generating means 1 and the magnetic shielding means 3 are opposed to each other. The magnetic field generating means 1 and the magnetic detecting means 2 while maintaining the relationship, or
At least one of the magnetic shielding means 3, which is formed by forming a plurality of aligned slits 4 at a pitch p, is configured to be movable in the direction in which the slits 4 are aligned (in the direction of arrow A).

In such a magnetic encoder, a part 5b (not shown) of the upward magnetic field 5 generated by the magnetic field generating means 1 is absorbed by the magnetic shielding means 3, and the other part 5a passes through the slit 4 and is input to the magnetic detecting means 2. do.

Then, the magnetic detection means 2, as shown in FIG. 1 (b),
An output that produces a peak corresponding to the pitch p of the slits 4 is obtained.

[Effect]

In Fig. 1, the width of the slit 4 can be formed to about 5 μm by using etching technology, etc., and the resolution of a magnetic encoder in which the slit 4 with a width of 5 μm is formed at a pitch of 10 μm is the same as that of a rotating drum. This is four times as large as a conventional magnetic encoder that uses a magnetic pattern magnetized on top.

〔Example〕

EMBODIMENT OF THE INVENTION Below, the magnetic encoder by the Example of this invention is demonstrated using drawing.

FIG. 2 is a side view (A) of a rotary magnetic encoder according to an embodiment of the present invention and a plan view (0) of its rotating disk, and FIG. 3 is a circuit diagram of a magnetic detection measurement system.

In FIG. 2, a magnetic encoder 24 that detects the rotation angle of the rotating shaft 21 is a disc made of a material that shields magnetism, such as permalloy, and in which a large number of slits 25 are formed on the same circumference with a fixed angle pinch. (Magnetic shielding means) 26, a permanent magnet 27 corresponding to the magnetic field generating means 1, and a magnetic detector 28 containing a magnetic resistance element and corresponding to the magnetic detecting means 2, the permanent magnet 27 and the magnetic detector 28 being circular. Board 26
are fixed by appropriate means so as to face each other across the slit 25 forming portion.

In the figure, 22 is a flange formed integrally with the rotating shaft 21, and 23 is a metal fitting for fixing the disk 26 to the front surface of the flange 22.

In the magnetic encoder 24 configured in this way, a portion 29b (not shown) of the magnetic field 29 generated by the permanent magnet 27
is shielded by the disk 26, and the other part 29a is shielded by the slit 25
and enters the magnetic detector 28. Therefore, the rotating shaft 2
1, the magnetic detector 28 detects the pulse train of the passing magnetic field B' and outputs an output that has a peak at the pitch of the slits 25.

In FIG. 3, 31 is an equivalent circuit of a magnetic detector 280 that utilizes the magnetoresistive effect of a ferromagnetic material, 32 is a constant current source, and 33
34 is an unbalanced voltage adjustment amplifier circuit, and 34 is a differential amplifier circuit. By changing the voltage V applied to the input terminal 35 of the constant current source 32, the current I applied to the magnetic detector 2 can be changed. The unbalanced voltage that arises can be adjusted by a variable resistor R. and,
The output of the magnetic detector 28 passes through a differential amplifier circuit 34 and is amplified, for example, about 100 times, and is measured and recorded by a digital multimeter, an X-Y recorder, etc. connected to an output terminal 36. .

In the embodiment described above, a permanent magnet 27 is used as the magnetic field generating means 1, and a magnetic detector 28 using magnetic resistance of ferromagnetic metal is used as the magnetic detecting means 2. these are,
Permanent magnet 27 does not use electric power, magnetic detector 28
This is because it is stable against temperature changes and has excellent ability to detect minute magnetic fields, but the present invention is not limited to such permanent magnets 27 and magnetic detectors 28. For example, an electromagnet may be used as the magnetic field generating means 1 to detect magnetic fields. It should be noted that means 2 can use a method using semiconductor magnetoresistance, a method using the Hall effect, or a magnetic head.

〔Effect of the invention〕

As explained above, according to the present invention, the pinch of the magnetic pulse train can be formed finer than before, and the resolution can be increased to about four times that of the conventional method.

In addition, the magnetic shielding means is lightweight by using a thin plate with a thickness of about 0.05 to 0.5 mm, which reduces the inertial force when the magnetic shielding means is moved, and has the effect of stabilizing the measured values. .

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of the basic configuration of the present invention and its output characteristic diagram. FIG. 2 is a side view of a rotary magnetic encoder according to an embodiment of the present invention and a plan view of its rotating disk. FIG. FIG. 4 is a circuit diagram of a magnetic detection measurement system. FIG. 4 is a perspective view showing a conventional magnetic encoder. 1 is a magnetic field generating means, 2 is a magnetic detecting means, 3 is a magnetic shielding means, 4.25 is a slit, 24 is a magnetic encoder, 26 is a disk (magnetic shielding means), 27 is a permanent magnet (magnetic field generating means), 28 is a magnetic detector (magnetic detection means), and p is a slit drilling pitch. 1 Yu Ying 1; ri suit Qi Liaoyu-P crotch ■ transfer Tochi Fang Huong (c7) $1 figure

Claims (4)

[Claims] (1) A magnetic field generating means (1), a magnetic detecting means (2) facing the magnetic field generating means (1) separated by an appropriate amount, and a magnetic field generating means (1) and the magnetic detecting means (2). The magnetic field generating means (1) and the magnetic shielding means (3) are arranged between opposing sides and have a large number of slits (4) arranged and bored in a plate of magnetic shielding material at appropriate intervals (p). Magnetic detection means (2)
Alternatively, a magnetic encoder characterized in that at least one of the magnetic shielding means (3) is configured to move in the direction in which the slits (4) are aligned. (2) The magnetic encoder according to claim 1, wherein the magnetic field generating means (1) is a permanent magnet. (3) The magnetic encoder according to claim 1, wherein the magnetic detection means (2) is a magnetoresistive element. (4) The magnetic encoder according to claim 1, wherein the magnetic shielding material is permalloy.