JPH09318391A - Magnetic type encoder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the resolution of a magnetic type encoder by a simple method and the achieve a high accuracy in measurement. SOLUTION: A highly permeable magnetic material 15, which forms a regular pattern along the moving direction of a detecting part, is applied in a magnetic- flux generating part, which generates the uniform magnetic flux in the moving range of the detecting part, and the planar part of a scale 11 between the magnetic-flux generating part and a magnetic sensor. Thus, the position information of the scale 11 is recorded by the change in magnetic flux density. When respect to the change in magnetic flux toward the magnetic sensor, all the surface of the scale 11 has the same polarity. Therefore, even if the pitch of the scale 11 is miniaturized, the reduction of the magnetic flux caused by the diatance from the surface of the scale 11 can be suppressed. Therefore, the pitch of the scale 11 can be miniaturized readily by already-existing thin-film technology. Thus, the resolution of the encoder can be enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic encoder for measuring length and angle, and more particularly to a magnetic encoder having a high resolution.

[0002]

BACKGROUND ART FIG. 5 shows an example of a conventional magnetic encoder. The magnetic encoder is a long flat scale 33.
And a detection unit 17 attached so as to move relative to the scale 33. The scale 33 has a base 35 and a magnetic medium 13 mounted on the base 35. When the magnetic medium 13 is initially unmagnetized, it is magnetized by external means to form NS magnetic poles at fine intervals. Are alternately provided regularly, and position information as a scale is recorded. In such a scale 33, since adjacent magnetic poles are always different poles, a magnetic sensor 19 incorporated in the detector 17 detects a leakage magnetic flux between the different poles to form a magnetic encoder. .

[0003]

In such a conventional magnetic encoder, if the pitch of the scale 33 is made fine to increase the resolution as shown in FIGS. 6 (a) and 6 (b), it is relatively different. The distance between the poles is shortened and the range of the leakage magnetic flux to the outside is narrowed, so that it is sufficient to use the magnetic sensor 19 with higher sensitivity or to improve the machining accuracy to narrow the gap between the magnetic sensor 19 and the scale 33. It was not possible to obtain sufficient signal detection sensitivity. Therefore, the magnetic encoder has a problem that the resolution cannot be increased by a simple method.

The present invention has been made in view of the above circumstances, and an object thereof is to increase the resolution of a magnetic encoder by a simple method and improve the accuracy of measurement.

[0005]

In order to achieve the above-mentioned object, the present invention comprises a scale in which position information is recorded by a change in magnetic flux density, and a magnetic sensor incorporated in a detecting section capable of moving relative to the scale. In the equipped encoder,
The scale has a magnetic flux generating section that generates a uniform magnetic flux within the moving range of the detecting section, and a regular pattern along the moving direction of the detecting section on the scale plane section between the magnetic flux generating section and the magnetic sensor. It is a means for solving the problem by applying a high magnetic permeability material to be formed.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. In all the drawings, components denoted by the same reference numerals represent the same components. FIG. 1 is a schematic configuration diagram of a magnetic encoder that is a first embodiment of the present invention. The scale 11 has a constant gap G on the surface of the magnetic medium 13 uniformly magnetized in the Z-axis direction.
It is constituted by adhering the high magnetic permeability material 15 at / 2. 2A and 2B are schematic diagrams showing the magnetic flux on the scale 11 of the aa line and bb line sectional views of FIG. Since the magnetic flux from the magnetic pole easily passes through the high magnetic permeability material 15,
The magnetic flux spreads in the Z-axis direction in a portion where the high magnetic permeability material 15 exists, and conversely, the magnetic flux spreads in a portion where the high magnetic permeability material 15 does not exist becomes small. That is, the magnetic flux density in the Z-axis direction in the portion where the high magnetic permeability material 15 exists and the portion where the high magnetic permeability material 15 does not exist periodically change on the scale 11 at a constant interval G / 2.

FIG. 3 is a diagram showing the positional relationship between the magnetic sensor 19 incorporated in the detection unit 17 and the scale 11.
In the magnetic sensor 19, ferromagnetic magnetoresistive elements 21 and 23 are connected in series at an interval H, and a voltage supply terminal 25 and an output terminal 27 are formed. The detection unit 17 uses the scale 1
The magnetic sensor 19 is arranged so as to be freely movable in the X-axis direction on the magnetic recording medium 1, and the magnetic sensor 19 detects the magnetic flux density that changes according to the relative movement amount of the detection unit 17 and the scale 11. The electric resistance R of each of the ferromagnetic magnetoresistive elements 21 and 23 is the angle between the current vector and the magnetization vector θ, the resistance component not dependent on the angle θ is R 0, and the resistance component dependent on the angle θ is Δ
It is known that R is represented by R = R0 + ΔR × COS 2θ.

In such a magnetic encoder, since the magnetic flux density in the Z-axis direction changes periodically on the scale 11 at a constant interval G / 2, the magnetization vectors of the ferromagnetic magnetoresistive elements 21 and 23 are also scaled. On 11 for the current vector,
The electric resistance corresponds to the relative movement amount between the detection unit 17 and the scale 11. Here, the distance H between the ferromagnetic magnetoresistive elements 21 and 23 and the pitch G of the high magnetic permeability material 15 are H = (3G) /
Set to 4. The electric resistances Re and Rf of the ferromagnetic magnetoresistive elements 21 and 23 are, at the position X of the magnetic sensor 19,

[0009]

[Equation 1]

Can be represented by At this time, if the voltage V is input from the voltage supply terminal 25, the magnetic sensor 1 of FIG.
When the ferromagnetic magnetoresistive elements 21 and 23 are connected in series as in 9, the voltage Vout on the output terminal 27 is

[0011]

[Equation 2]

Can be expressed as This output terminal 27
By detecting the phase of the signal of the upper voltage Vout, the relative movement amount between the detection unit 17 and the scale 11 can be detected. In order to improve the accuracy of position reading of the encoder, it is necessary to make the scale pitch finer, and in the magnetic encoder described above, it is possible to easily make the scale pitch finer by the existing thin film process technology. It is possible.

FIG. 4 is a schematic configuration diagram of a scale in which the pitch of the scale of the magnetic encoder according to the second embodiment of the present invention is miniaturized. A metal thin film of a high magnetic permeability material is vapor-deposited on the surface of a glass substrate 29 having a thickness of about 0.5 mm in the Z-axis direction, and 100 in the X-axis direction by etching technology.
A pattern 31 having a width of about μm is formed. By adhering the glass substrate 29 having the fine pattern 31 formed on the surface of the magnetic medium 13 uniformly magnetized in the Z-axis direction, the scale pitch can be reduced.

Although the present invention has been described above with reference to the preferred embodiment, the present invention is not limited to this embodiment, and modifications can be made without departing from the gist of the present invention. . For example, in the above-described embodiment, the magnetic sensor is configured by using the ferromagnetic magnetoresistive element, but it may be configured by using a flux gate, an MR element, a Hall element, or the like. Further, in the above-described embodiment, the description has been limited to the linear encoder, but the present invention can also be implemented in a rotary encoder and a two-dimensional encoder.

A magnetic flux generating section for generating a uniform magnetic flux,
By applying a high-permeability substance that forms a regular pattern along the moving direction of the detection unit to the scale plane portion between the magnetic sensor that detects the change in the magnetic flux and the magnetic flux density in the Z-axis direction, Record due to changes in. The change in the magnetic flux density toward the magnetic sensor is the same polarity on the scale surface, so compared to the conventional magnetic encoder, it is possible to suppress the decrease in the magnetic flux due to the distance from the scale surface. The pitch of the scale can be easily miniaturized. Therefore, the resolution of the magnetic encoder can be increased by a simple method, and the accuracy of measurement can be improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a magnetic encoder that is a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a magnetic flux in a cross section taken along the line aa and the line bb of FIG.

FIG. 3 is a diagram showing a positional relationship between a magnetic sensor and a scale of the magnetic encoder according to the first embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of a scale of a magnetic encoder that is a second embodiment of the present invention.

FIG. 5 is a conventional magnetic encoder.

FIG. 6 is a sectional view of a scale of a conventional magnetic encoder.

[Explanation of symbols]

 11, 33 Scale 13 Magnetic Medium 15 High Permeability Material 17 Detecting Section 19 Magnetic Sensor 21, 23 Ferromagnetic Magnetoresistive Element 25 Voltage Supply Terminal 27 Output Terminal 29 Glass Substrate 31 Pattern 35 Base

Claims (3)

[Claims] 1. An encoder comprising a scale in which position information is recorded by a change in magnetic flux density, and a magnetic sensor incorporated in a detecting section capable of moving relative to the scale, wherein the scale is within a moving range of the detecting section. A magnetic flux generator that generates a uniform magnetic flux and a high-permeability substance that forms a regular pattern along the moving direction of the detector are applied to the scale plane portion between the magnetic flux generator and the magnetic sensor. A magnetic encoder characterized in that 2. An encoder provided with a scale in which position information is recorded by a change in magnetic flux density, and a magnetic sensor incorporated in a detecting section capable of moving relative to the scale, wherein the scale is within a moving range of the detecting section. It has a flat plate-shaped magnet portion that generates a uniform magnetic flux, and a high-permeability substance that forms a regular pattern along the moving direction of the detection portion is applied to the surface of the magnet portion that faces the magnetic sensor. A magnetic encoder characterized in that 3. An encoder provided with a scale in which position information is recorded by a change in magnetic flux density and a magnetic sensor incorporated in a detection unit capable of moving relative to the scale, wherein the scale is within a moving range of the detection unit. A flat magnet portion that generates a uniform magnetic flux, and a high-permeability substance that is provided between the magnet portion and the magnetic sensor and that forms a regular pattern along the moving direction of the detection portion is applied to the surface of the magnet portion. A magnetic encoder characterized in that the magnetic encoder is made of a strip glass.