JPS63235815A - Magnetic encoder - Google Patents

Abstract

PURPOSE:To obtain an apparatus resistant against external noise, simple in the wiring of a pattern and easy to adjust a gap, by providing a high permeability magnetic body to a magnetoresistance effect element pattern detecting the magnetic flux leaked from each magnetic track of a magnetic sensor on a single side or both sides thereof. CONSTITUTION:A magnetic track 6 having a magnetized zone and a non- magnetized zone and having a magnetic zone consisting of at least two magnetic poles is constituted of at least one magnetic disc 5 composed of a magnetic medium provided on a moving or rotating body and a magnetic sensor 3 provided with magnetic resistance effect element patterns R1-R5 composed of a ferromagnetic material. Then, by forming a high permeability magnetic film pattern 8 on the single side or both sides of each of the patterns R1-R5 detecting the magnetic flux leaked from the track 6, the variation of the leak magnetic flux is averaged and the pulsation of an output wave form is eliminated.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to the rotational angle of a rotating shaft of a servo motor used in an NC machine tool or the like, or the position of a moving body such as a near-motor application device that performs linear motion. The present invention relates to a magnetic encoder that detects a change in resistance of a magnetoresistive element due to a magnetization pattern formed on the surface of a body or a moving body.

[Conventional technology]

A magnetic encoder is one method for accurately measuring the rotation speed and rotation angle of machine tools. There are two types of magnetic encoders: an absolute type that determines the initial position at startup, and an incremental type.

As an absolute type magnetic encoder, for example, as seen in Japanese Patent Application Laid-Open No. 57-123494, a plurality of magnetic tracks are formed according to the required accuracy, and each track is arranged in the circumferential direction with 2. (n is 1 or more). A rotating magnetic disk is divided into segments (an integer of A magnetic sensor is known in which a plurality of magnetoresistive elements are arranged in a diametrical direction of a disk. In this case, the magnetized zone is multi-pole magnetized in the longitudinal (circumferential) direction with a magnetization length (magnetization pitch) λ, and the number of magnetic sensors facing this is two for one magnetic track. A set of magnetoresistive element patterns is formed, and the interval between two magnetoresistive elements is approximately 1/2 of the magnetization pitch λ.
It is said that

In addition, in an incremental type magnetic encoder, as shown in FIG. 9 (1), a magnetic medium 22 having a magnetic track 24 for incremental signals and a magnetic track 23 for reference position signals, and a magnetoresistive magnetic medium 22 opposed to the magnetic medium 22 are provided. Elements R+, R2, R-(R+.

The quasi-position signal and the incremental signal are read by a magnetic sensor 21 equipped with R2 for detecting incremental signals and R2 for detecting reference I device signals.

(Problem to be solved by the invention) However, in the magnetic encoder of the conventional method, it is difficult to solve the problem in the magazine "Automatic Technology" published in 1986, 18altJ3.
What is reported on page 6 is a magnetic track T as shown in FIG. 8 (1). -TJ and magnetoresistive element -Ro,,
Ro2. ..., a combination of magnetic sensors including R32, the magnetic pole part of the magnetized zone and the intermediate part of the magnetic pole,
Or, because the strength of the leakage magnetic flux changes at the boundary between the magnetized zone and the non-magnetized zone, the magnetoresistive effect element R6, #R
A very large pulsation (portion a in the figure) as shown in FIG. 8(2) occurs in the resistance changes e0 to e3 every 32i.

Furthermore, if the gap between the magnetic medium and the magnetic sensor is narrow, output fluctuations occur at the boundary between the magnetized zone and the non-magnetized zone (b in the figure).

As shown in Fig. 8 (3), even if a bridge is constructed with a pair of magnetoresistive elements separated by λ/2 and a fixed resistor R to obtain an output, as shown in Fig. 8 (4), Pulsation remained in the output waveform. The fluctuation in the output as shown in b in Figure 8 (2) is also reflected in the signal output as signal V1 in Figure 9 (2) for determining the reference position of the incremental magnetic encoder configured as in Figure 9 (+). It was appearing. Furthermore, when the gap between the magnetic medium and the magnetic sensor 21 is narrow, output fluctuations occur due to interference of leakage magnetic flux from the incremental signal magnetic track 24 as shown in (2) 4 in FIG. 9. For this reason, magnetic encoders using conventional magnetic sensors have the problem of being susceptible to external electromagnetic noise. In addition, since two magnetoresistive elements are used to extract the signal from one magnetic track like an absolute magnetic encoder, the pattern wiring of the magnetic sensor becomes complicated, and in order to prevent output fluctuations. It is necessary to accurately maintain the gap between the magnetic medium and the magnetic sensor at an optimum value, and there is a problem in that it is necessary to take measures against gap fluctuations due to factors such as machining grain size and temperature rise.

Therefore, an object of the present invention is to provide a magnetic encoder that is resistant to external noise, has simple wiring for magnetic sensor patterns, and has easy gap adjustment.

[Means for solving problems]

The magnetic encoder of the present invention has a magnetized zone and a non-magnetized zone, and the magnetic zone has at least one magnetic track consisting of at least two magnetic poles on a moving body or a rotating body.
In an electric encoder comprising a magnetic sensor including a magnetic medium and a ferromagnetic +1 body magnetoresistive element, the magnetic sensor is provided with a high permeability magnetic material on one or both sides of a magnetoresistive element pattern.

[Effect]

By forming a pattern made of a magnetic film with high magnetic permeability on one or both sides of the magnetoresistive element pattern that detects leakage magnetic flux from a magnetic track, leakage magnetic flux from a multipolar magnetized zone can be detected. As a result, the pulsation of the output waveform is eliminated. In this case, if the magnetized pitch of the magnetized zone is λ, then if the sum of the widths of the magnetoresistive element pattern and the high-speed 6IA rate magnetic material pattern is less than λ, the effect of averaging leakage flux fluctuations will be small. The effect of suppressing pulsation in the output waveform becomes smaller.

Therefore, it is suitable that the total width of these patterns is λ or more.

In addition, in an incremental magnetic encoder, if the interval between the high permeability magnetic material pattern and the magnetoresistive element pattern is larger than 5 scales, it becomes difficult for the magnetic flux of the magnetoresistive element to enter from the high permeability magnetic material, thereby suppressing output fluctuations. It becomes ineffective.

Therefore, the distance between the high permeability magnetic material pattern and the magnetoresistive element pattern is preferably 5 μm or less.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 (1) is an embodiment of the absolute magnetic encoder of the present invention, and is a configuration diagram when used to detect the rotation angle of a motor.

A concentric magnetic track 41 is placed on the shaft 1 of the motor 2.
-4- A magnetic disk 5 is attached, and a magnetic sensor 3 is attached to the motor 2 by a sensor support 4.

FIG. 1(2) is a diagram showing the arrangement relationship between the magnetic track 6 and the magnetoresistive element patterns R1 to R5 of the magnetic sensor 3 in the absolute magnetic encoder of FIG. 1(1). In each magnetic track 6, magnetoresistive elements -R1 to R5 for detecting leakage magnetic fields from 11 magnetic zones are held at minute intervals of about 50 mm in the direction across the magnetic track 6, respectively. In this example, the magnetic track 6 is 5
In other words, the case is shown in which the rotation angle is detected using a particle size obtained by dividing 501 rotations of the magnetic disk into 2'' = 32 pieces. However, in order to detect the rotation angle with even higher precision, a magnetic track and a magnetoresistive effect element facing it are used. It is better to increase the number of

FIG. 2 is a diagram showing an example of the pattern of the magnetic sensor 3. Here, the magnetic sensor 3 is shown when the magnetization and pitch p in the magnetization zone of the magnetic track 6 are about 70 scales, and the pattern R of the magnetoresistive element for detecting the leakage magnetic field from the magnetic track 6 is shown. -R5 consists of an 82Ni-Fc film with a width of 70u+ and a thickness of 500 mm, which is deposited on the glass substrate and then patterned by photolithography.

The high magnetic permeability magnetic body 8 has magnetoresistive effect element patterns R, -R.
, is made of the same 82Ni-Fe film as the magnetoresistive film, and is deposited at the same time as the magnetoresistive film, and is formed in a pattern with a width of 30 - on both sides of the magnetoresistive element patterns R9 to R5 with a gap g of four scales in between. Width of patterns R1 to R6 and high speed M! The total length of the width of the L-rate magnetic material pattern 8 is longer than the magnetized length of one of the magnetized zones. The gap g in this case is provided to prevent a short circuit between the magnetoresistive elements R3 to R5 and the pattern of the high permeability magnetic material 8.
A gap is not necessary when an electrically insulating high permeability magnetic material, such as a magnetic ferrite film, is used. A power line and a signal line are connected to the magnetoresistive element patterns R1 to R5 by a lead wire pattern 11 (in the figure, 9 is a power terminal, and 10 is a signal line end f) made of a Gu vapor deposited film.

FIG. 3<1) is a diagram showing the opposing relationship between the magnetic sensor 3 and the magnetic track 6, FIG. 3(2) is a diagram showing how leakage magnetic flux enters the magnetoresistive element r-pattern, Figure 3 (
3) is a connection diagram of the magnetoresistive elements R8 to R= and the fixed resistor R, and Figure 5 shows the output el ” Ore 2 e Q
+ ””, 'B 5 e O waveform diagram.

When the magnetic sensor 3 is placed opposite the magnetic track 6 as shown in FIG. 3(1), high permeability magnetic material is formed on both sides in the magnetoresistive element patterns R and -R5 as shown in FIG. 3(2). Since the leakage magnetic flux that has entered the body membrane enters through the gap g, the fluctuation of the leakage magnetic flux is Y-restricted, and the fluctuation in the magnetized portion is reduced compared to the case where the magnetoresistive effect element patterns R8 to R5 are used alone. This makes it less susceptible to magnetic flux fluctuations. A similar effect is also observed when a high permeability magnetic film pattern is formed only on one side of the magnetoresistive element patterns R and -R5. In addition, the output fluctuation near the magnetic pole (Fig. 8 (
2) b) occurs because the magnetoresistive effect element is sensitive to the horizontal component of the magnetic flux at the position of the non-cyelamagnetic portion X2 near the magnetic pole, as shown in the cross-sectional view of the magnetic track and magnetic sensor in Figure 10. It is something. If the patterns are arranged so that the sum of the widths of the magnetoresistive element patterns R1 to R5 and the high permeability magnetic material pattern 8 is greater than the magnetized length as in this embodiment, as shown in FIG. Since the leakage magnetic flux in the non-magnetized portion near the magnetic pole easily passes through the high permeability magnetic film 8 which is close to the magneto-resistance effect element, no magnetic flux enters the magnetoresistive element. For this reason! The output fluctuation near the fi pole disappears. Therefore, as shown in FIG. 3(3), the magnetoresistive elements R, -R5 and the fixed resistor R are connected, and the potentials e, -e5 at the connection points and the reference voltage e. Which difference should be taken, the outputs are e1-eo, e2-eo, and e3-eo, which are not shown in FIG.

e 4 ''-e Q + e 5e O is obtained. As can be seen from this, the output of the absolute magnetic encoder of this embodiment contains the magnetized zone of the magnetic track as seen in the conventional example. There is no output pulsation at h4.

In this example, the magnetization tracks are formed in a solid concentric manner.
Regarding the encoder of the type using the 18 disk, as shown in FIG. 6, another configuration example has a multi-pole magnetized zone and a non-magnetized zone on the side surface of the cylindrical magnetic drum 12. It is also possible to suppress output pulsation by combining the magnetic sensor 14 (attached to the motor 16 with a sensor support 15) according to the present invention to an encoder of the type in which a magnetic track 13 is formed. This is clear from the above-mentioned operation explanatory diagram. Further, even when the magnetic track is formed in a straight line, similar effects can be obtained by using the magnetic sensor of the present invention.

FIG. 7(1) is a diagram showing the arrangement relationship between the magnetic track and the magnetoresistive element of the magnetic sensor in an embodiment of the incremental magnetic encoder of the present invention. The magnetic medium is formed on the side surface of the cylindrical magnetic drum, and the magnetized pitch λ of the incremental signal magnetic track 20 on the magnetic medium and the magnetized length λ of the reference position magnetic track 19 are the same, 150 uI. It is. The gap between the magnetic drum and the magnetic sensor 17 is 30 to 100 mm. Adjusted to. The pattern of the magnetic sensor 17 is a magnetoresistive element pattern for incremental signal detection which is far away from the reference position signal detection magnetoresistive element pattern R2 by (n 10%) λ (n: an integer greater than or equal to 0 and 1). It is composed of R,, R2. Patterns R2 and R, R2 are made of 32Ni-Fc IIQ with a thickness of 600 mm, and are made of glass'', t
- The pattern is created by photolithography after being deposited on the plate. The high magnetic permeability magnetic material 18 is made of the same B2Ni-Fe film as the magnetoresistive element pattern R2, and is deposited at the same time as the magnetoresistive film, with a gap of 4 ul in between, and on both sides of the magnetoresistive element pattern R2 with a width of 70 mm.
A pattern of scales is formed. Patterns R2 and R
,, R2 are connected as shown in FIG. 7(2), and the reference voltage e is set. Which difference is taken to obtain the output e2 as shown in Fig. 7 (3)
We obtained eo + e ie. In addition, Figure 7 (3
), the gap between the magnetic drum and the magnetic sensor 17 is 30-
The case is shown below. As will be seen, regarding the reference position signal, pulsations in areas other than the reference position signal output and fluctuations in the output before and after the reference position signal output, which were observed in the conventional example, are not observed. Moreover, even if the gap between the magnetic drum and the magnetic sensor 17 is changed from 30μ to too p,
l, t, level pre-output signal e2-eO has a gap of 30u
As in the case of +, no pulsation or fluctuation was observed. This example describes the case where the magnetization pitch of the incremental signal and the magnetization length of the reference position signal are the same, but the reading accuracy of the reference position can be increased by 1. Even when the width is made smaller than the magnetization pitch of incremental No. 13, the present invention is effective in suppressing pulsations and output fluctuations in the reference position signal output.

Furthermore, it is clear from the above description of the operation that the same effects as in the embodiments can be obtained by the present invention even when the magnetic track for incremental signals and the magnetic track for reference position signal are formed in a straight line.

In addition, although the above embodiment describes an example in which the same material as the magnetoresistive element 11Q is used as the high magnetic permeability magnetic film, 1'e, Go,
Ni and its alloys or Go-7,r-Nb.

Go-Zr-Mo, Ni-Zn ferrite, Mn-
It is clear that the same effect as in this embodiment can be obtained even if a film of Zn ferrite or the like is placed on one side or both sides of the magnetoresistive element pattern.

(Effects of the Invention) As explained above, the present invention provides a magnetic sensor with a high magnetic permeability magnetic material on one or both sides of a magnetoresistive element pattern that detects leakage magnetic flux from each magnetic track. Since there is no pulsation in the output signal from the magnetic sensor regarding the movement position or movement position, it is possible to manufacture highly reliable angle and position detectors that are resistant to external noise. Since only one effect element pattern is required, pattern wiring is simplified and the yield of sensor production is improved.Furthermore, even if the gap between the magnetic medium and the magnetic sensor changes, the reference position signal does not pulsate or fluctuate, making it easy to adjust the gap. This has the effect of making it easier and improving productivity.

[Brief explanation of the drawing]

Fig. 1 (1) is an embodiment of the absolute magnetic encoder of the present invention, and is a configuration diagram when used to detect the rotation angle of a motor. Fig. 1 (2) is an example of the absolute magnetic encoder of Fig. 1 (+). Magnetic track 6 and magnetic sensor 3
magnetoresistive element R. 2 is a diagram showing an example of the pattern of the magnetic sensor 3, FIG. 3 (1) is a diagram showing the opposing relationship between the magnetic sensor 3 and the magnetic track 6, and FIG. ) is a diagram showing how leakage magnetic flux enters the magnetoresistive element pattern, Figure 3 (3) is a connection diagram of the magnetoresistive effect R, -R6 and the fixed resistor R, and Figure 4 is a diagram showing the details of the present invention. Diagram to explain,
Figure 5 shows the output el -〇〇 + e2 in Figure 3.
``'-e O+ ''''+ e5-eo waveform diagram, FIG. 6 is a perspective view of another embodiment of the absolute magnetic encoder of the present invention, and FIG. 7 is an embodiment of the incremental magnetic encoder of the present invention. 8(1) is a diagram showing a combination of a magnetic track and a magnetic sensor of an absolute type magnetic encoder in a conventional example, and FIG. 8(2) is a diagram showing each magnetoresistive element pattern RO in FIG. 8(1), ,R
o2. ..., a diagram showing the resistance change occurring in R3,
Figure 8 (3) shows the magnetoresistive element pattern R8° to R3.
, and the connection diagram of fixed resistor R, Fig. 8 (4) is the same as Fig. 8 (3).
Each output e in the connection. -e4 waveform diagram, FIG. 9 is a perspective view of an incremental encoder in a conventional example and a diagram showing an example of an output signal, and FIG. 1O is a diagram showing the principle of occurrence of output fluctuation in the conventional example. 1------------Shaft, 2.16
......Motor, 3.17...Magnetic sensor, 4.15...
......Sensor support stand, 5----------
...Magnetic disc, 6, 19.20...Magnetic track, 7...Lead wire, 8.18
−・・・・・・・High magnetic permeability magnetic material, 9・・・・・・・
・・・・・・・・・Power terminal, 10・・・・・・・・・
・・・・・・Signal line terminal, 11・・・・・・・・・・・・
...Lead wire pattern, 12...
...Magnetic drum, R0 to R5--Magnetoresistive element pattern, ToNT4...Track, R----------Identification resistance.

Claims (1)

[Claims] 1. A magnetic medium that has a magnetized zone and a non-magnetized zone, and the magnetic zone has at least one magnetic track consisting of at least two magnetic poles on a moving body or a rotating body; A magnetic encoder comprising a magnetic sensor equipped with a ferromagnetic magnetoresistive element, characterized in that the magnetic sensor is equipped with a high permeability magnetic body on one or both sides of a magnetoresistive element pattern. 2. Claim 1: The total length of the width of the magnetoresistive element pattern and the width of the high permeability magnetic material pattern of the magnetic sensor is greater than the length of one magnetized piece in the magnetized zone.
Magnetic encoder described in section. 3. The magnetic encoder according to claim 1, wherein the magnetic track is provided according to the required accuracy and is capable of measuring absolute position. 4. The magnetic encoder according to claim 1, wherein one of the magnetic tracks is provided with a magnetized portion consisting of two magnetic poles that generate a reference position signal at one position during one rotation or one stroke. 5. The magnetic encoder according to claim 4, wherein a distance between the pattern of the magnetoresistive element and the high permeability magnetic material is 5 μm or less.