JP5687083B2 - Magnetic sensor and linear encoder - Google Patents

Description

  The present invention relates to a magnetic sensor and a linear encoder in which a substrate surface of a sensor substrate on which a magnetoresistive pattern is formed is arranged perpendicular to a magnetic pole surface of a magnetic scale.

  A magnetic sensor that detects relative movement of a magnetic scale in which N poles and S poles are alternately arranged based on an output signal from a magnetoresistive pattern formed on the surface of a sensor substrate is described in Patent Document 1. The magnetic sensor disclosed in this document uses a plurality of magnetoresistive patterns for detecting the A phase and the B phase, which detect the movement of the magnetic scale with a phase difference of 90 ° from each other, at predetermined intervals in the relative movement direction. By forming them in parallel, the harmonic component superimposed on the output signal from each magnetoresistive pattern is canceled. In this document, the sensor substrate is arranged with the substrate surface facing the magnetic pole surface of the magnetic scale.

JP 63-225124 A

  Here, if the sensor substrate is arranged in a state in which the substrate surface is perpendicular to the magnetic pole surface of the magnetic scale and parallel to the relative movement direction, the sensor substrate is within the range of the vertical length of the magnetoresistive pattern formed on the substrate surface. Since the magnetic field in front of the magnetic pole surface of the magnetic scale can be detected, it is possible to increase the gap between the sensor substrate and the magnetic scale as compared with the case where the substrate surface is disposed in opposition to the magnetic pole surface of the magnetic scale. It becomes possible. However, when the magnetic sensor of Patent Document 1 is arranged in a state where the substrate surface is perpendicular to the magnetic pole surface of the magnetic scale, the harmonic component superimposed on the output signal from each magnetoresistive pattern is not canceled, and the position detection accuracy decreases. There is a problem of doing.

  In view of these points, the problem of the present invention is that the output signal from the magnetoresistive pattern formed on the substrate surface when the sensor substrate is arranged in a state where the substrate surface is perpendicular to the magnetic pole surface of the magnetic scale. An object of the present invention is to provide a magnetic sensor and a linear encoder that can reduce harmonic components superimposed on a fundamental wave component.

In order to solve the above problems, the present invention provides a magnetic sensor for detecting a relative movement of a linear magnetic scale in which N poles and S poles are alternately arranged at a predetermined magnetic pole pitch. A sensor substrate perpendicular to the magnetic pole surface of the scale and parallel to the relative movement direction, a fundamental wave detecting magnetoresistive pattern formed on the substrate surface, and a fundamental wave component of an output signal from the fundamental wave detecting magnetoresistive pattern In order to remove harmonic components superimposed on the substrate, the substrate surface is formed at a position away from the fundamental wave detecting magnetoresistive pattern by a predetermined distance shorter than 1/8 of the magnetic pole pitch in the relative movement direction. a magnetoresistance pattern harmonic component removing connected in series with the magnetoresistive pattern fundamental wave detection, the said fundamental wave detection magnetoresistance
The anti-pattern and the harmonic component removing magnetoresistive pattern have the same shape, and the predetermined distance is in the following range when the magnetic pole pitch is 1.
0.06 ≦ D ≦ 0.10
D: predetermined distance

In the present invention, the predetermined distance is preferably in the following range when the magnetic pole pitch is 1.
0.086 <D <0.098
D: predetermined distance

  In the case where the sensor substrate is arranged in a state in which the substrate surface is perpendicular to the magnetic pole surface of the magnetic scale and parallel to the relative movement direction, the inventor of the present invention moves from the fundamental wave detecting magnetoresistive pattern to the relative movement direction on the substrate surface. The fundamental wave detecting magnetoresistive pattern is formed by forming a harmonic component removing magnetoresistive pattern at a position separated by a predetermined distance shorter than 1/8 of the magnetic pole pitch and connecting it in series to the fundamental wave detecting magnetoresistive pattern. It has been found that the harmonic component superimposed on the fundamental component of the output signal from can be reduced or eliminated.

  In addition, the inventor makes a predetermined distance between the fundamental wave detecting magnetoresistive pattern and the harmonic component removing magnetoresistive pattern within the above range, so that a sine wave output signal having almost no distortion from the magnetic sensor. It was found that the detection error of the moving position of the magnetic scale can be made small.

  In this case, the fundamental wave detecting magnetoresistive pattern includes a pair of rectangular first strips extending parallel to a direction orthogonal to the magnetic pole surface and the pair of first strips extending in the relative movement direction. A first folded pattern composed of a first coupling part that couples the ends on the magnetic pole surface side, wherein the harmonic component removing magnetoresistive pattern extends in a direction perpendicular to the magnetic pole surface. A pair of rectangular second belt-shaped portions and a second folding pattern including a second connection portion extending in the relative movement direction and connecting the ends of the pair of second belt-shaped portions on the magnetic pole surface side. It is desirable. In this way, the end of the fundamental wave detecting magnetoresistive pattern and the end of the harmonic component removing magnetoresistive pattern are both located on the side opposite to the magnetic scale of the sensor substrate. Therefore, it becomes easy to perform wiring for the fundamental wave detecting magnetoresistive pattern and the harmonic component removing magnetoresistive pattern in a region opposite to the magnetic scale of the sensor substrate.

  In this case, the fundamental wave detecting magnetoresistive pattern includes a plurality of the first folded patterns, and the harmonic component removing magnetoresistive pattern includes the second folded pattern as the first folded pattern. The plurality of first folding patterns may be connected in series, and the plurality of second folding patterns may be connected in series.

  In the present invention, in order to detect the movement position of the magnetic scale with high accuracy, the A formed on the surface of the substrate for detecting the A phase and the B phase for detecting the movement of the magnetic scale with a phase difference of 90 ° from each other. A magnetoresistive pattern for phase B and a magnetoresistive pattern for phase B, and a magnetoresistive pattern for + a phase that detects movement of a magnetic scale with a phase difference of 180 ° as the magnetoresistive pattern for phase A and -a phase The B phase magnetoresistive pattern includes a + b phase magnetoresistive pattern and a -b phase magnetoresistive pattern that detect the movement of the magnetic scale with a phase difference of 180 °. The + a phase magnetoresistive pattern includes first and second + a phase magnetoresistive patterns formed at positions separated from each other in the relative movement direction. The -a phase magnetoresistive pattern includes first and 2-a phase magnetoresistive patterns formed at positions separated from each other in the relative movement direction. First and second + b phase magnetoresistive patterns formed at positions separated in the relative movement direction, and the -b phase magnetoresistive patterns are formed at positions separated from each other in the relative movement direction. 1, comprising a 2-b phase magnetoresistive pattern, the first, 2 + a phase magnetoresistive pattern, the first, 2-a phase magnetoresistive pattern, and the first, 2 + b phase magnetoresistive pattern. Each of the pattern and the first and second 2-b phase magnetoresistive patterns includes the fundamental wave detecting magnetoresistive pattern and the harmonic component removing magnetoresistive pattern, and the first and second + The phase magnetoresistive pattern, the first, 2-a phase magnetoresistive pattern, the first, 2 + b phase magnetoresistive pattern, and the first, 2-b phase magnetoresistive pattern are full. It is desirable to constitute a bridge circuit.

  Next, the present invention can be a linear encoder including the magnetic sensor described above and a linear magnetic scale in which N poles and S poles are alternately arranged at the magnetic pole pitch. According to the present invention, in the output signal from the magnetic sensor, the harmonic component superimposed on the fundamental wave component is reduced or removed, so that the detection accuracy of the moving position of the magnetic scale is high.

  According to the present invention, when the sensor substrate is arranged in a state where the substrate surface is perpendicular to the magnetic pole surface of the magnetic scale and parallel to the relative movement direction, an output signal of a sine wave without distortion can be obtained from the magnetic sensor, The moving position of the magnetic scale can be accurately detected. Therefore, the gap between the magnetic sensor and the magnetic scale can be increased by arranging the sensor substrate so that the substrate surface is perpendicular to the magnetic pole surface of the magnetic scale and parallel to the relative movement direction.

It is explanatory drawing of the linear encoder to which this invention is applied. It is a circuit diagram of the magnetoresistive pattern currently formed in the substrate surface of a sensor substrate. It is the graph which shows the change of the resistance value of the magnetoresistive pattern for fundamental wave detection, and the magnetoresistive pattern for harmonic component removal, and the graph which synthesize | combined the waveform of the change of these resistance values. It is a graph of the error of the position detection by a linear encoder. It is explanatory drawing of the linear encoder of a comparative example. It is the graph of the change of the resistance value of the magnetoresistive pattern for fundamental wave detection of the magnetic sensor of a comparative example, and the graph of the error of the position detection by the linear encoder of a comparative example. It is a graph of the error of the position detection by the linear encoder of the modification when the distance etc. of the magnetoresistive pattern for fundamental wave detection and the magnetoresistive pattern for harmonic component removal are changed. It is a graph which shows the relationship between the error of the position detection by a linear encoder, and the distance of the magnetoresistive pattern for fundamental wave detection, and the magnetoresistive pattern for harmonic component removal.

  Hereinafter, an embodiment of a linear encoder to which the present invention is applied will be described with reference to the drawings.

(overall structure)
FIG. 1A is an explanatory diagram showing a schematic configuration of a linear encoder to which the present invention is applied, and FIG. 1B is a plan view of each magnetoresistive pattern. The linear encoder 1 of this example includes a linear magnetic scale 2 and a magnetic sensor 3 that detects a movement position of the magnetic scale 2 that relatively moves in the longitudinal direction.

  The magnetic scale 2 is alternately provided with N poles and S poles at a predetermined magnetic pole pitch P in the longitudinal direction. In this example, the magnetic pole pitch P is 10 mm. The magnetic sensor 3 includes a sensor substrate 4 on which eight magnetoresistive patterns (magnetoresistive elements) R1 to R8 are formed on a substrate surface 4a. The sensor substrate 4 is arranged such that the substrate surface 4 a is perpendicular to the magnetic pole surface 2 a of the magnetic scale 2 and parallel to the relative movement direction.

(Magnetic resistance pattern)
The sensor substrate 4 is made of glass, silicon, or glazed ceramic. The magnetoresistive patterns R1 to R8 are magnetic films such as NiFe formed on the sensor substrate 4 by vacuum deposition or sputtering and patterned by a normal photolithography process and an etching process. The distance between the patterns of the magnetoresistive patterns R1 to R8 is 1/8 of the magnetic pole pitch P. Each of the magnetoresistive patterns R1 to R8 removes the fundamental wave detecting magnetoresistive pattern 10 for detecting the fundamental wave and the harmonic component superimposed on the fundamental wave component of the output signal from the fundamental wave detecting magnetoresistive pattern 10. For this purpose, a magnetoresistive pattern 20 for removing harmonic components is provided.

  As shown in FIG. 1 (b), the fundamental wave detecting magnetoresistive pattern 10 is a pair of rectangular first electrodes extending in parallel to the direction perpendicular to the magnetic pole surface 2a from the edge of the sensor substrate 4 on the magnetic scale 2 side. Two sets of first folding patterns 14 including one belt-like portions 11 and 12 and a first connecting portion 13 that extends in the relative movement direction and connects the ends of the pair of first belt-like portions 11 and 12 on the magnetic pole surface 2a side. (1) and 14 (2). The first folded patterns 14 (1) and 14 (2) are connected in series by a connection portion 15 that extends in the relative movement direction at the end opposite to the magnetic pole surface 2a.

  The harmonic component removing magnetoresistive pattern 20 includes a pair of rectangular second strips 21 and 22 extending in parallel to a direction perpendicular to the magnetic pole surface 2a from the edge of the sensor substrate 4 on the magnetic scale 2 side, and relative movement. Two sets of second folding patterns 24 (1) and 24 (2) composed of second connecting portions 23 extending in the direction and connecting the ends of the pair of second strips 21 and 22 on the magnetic pole surface 2 a side. I have. The second folded patterns 24 (1) and 24 (2) are connected in series by a connection portion 25 that extends in the relative movement direction at the end opposite to the magnetic pole surface 2a.

  The fundamental wave detecting magnetoresistive pattern 10 and the harmonic component removing magnetoresistive pattern 20 have the same shape, and the harmonic component removing magnetoresistive pattern 20 moves from the fundamental wave detecting magnetoresistive pattern 10 to the moving direction of the magnetic scale 2. Are formed at positions separated by a predetermined distance D. The fundamental wave detecting magnetoresistive pattern 10 and the harmonic component removing magnetoresistive pattern 20 are the same as the first folded pattern 14 (2) on the side of the harmonic component removing magnetoresistive pattern 20 in the fundamental wave detecting magnetoresistive pattern 10. The magnetic pole of the second folded pattern 24 (1) on the side opposite to the magnetic pole surface 2a and the fundamental wave detecting magnetoresistive pattern 10 of the fundamental wave detecting magnetoresistive pattern 10 of the harmonic component removing magnetoresistive pattern 20 The end opposite to the surface 2a is connected in series by being connected by a third connection portion 16 extending in the relative movement direction.

  In this example, each of the first belt-like portions 11 and 12 and the second belt-like portions 21 and 22 has a length dimension of 1.5 mm and a width dimension of 0.015 mm. The predetermined distance D between the fundamental wave detecting magnetoresistive pattern 10 and the harmonic component removing magnetoresistive pattern 20 is 0.93 mm. The fundamental wave detecting magnetoresistive pattern 10 and the harmonic component removing magnetoresistive pattern 20 are formed with an error of 1 μm or less. The gap G between the fundamental wave detecting magnetoresistive pattern 10 and the harmonic component removing magnetoresistive pattern 20 and the magnetic pole surface 2a of the magnetic scale 2 is set to 2 mm.

  Here, the eight magnetoresistive patterns R1 to R8 detect the A phase (SIN phase) and the B phase (COS phase) that detect the movement of the magnetic scale 2 with a phase difference of 90 ° from each other.

  More specifically, the magnetoresistive pattern for detecting the A phase detects -a phase (-sin phase) and + a phase (+ sin phase) that detects the movement of the magnetic scale 2 with a phase difference of 180 °. -A phase magnetoresistive pattern and + a phase magnetoresistive pattern, and each of the -a phase magnetoresistive pattern and the + a phase magnetoresistive pattern is formed at positions separated from each other in the moving direction of the magnetic scale 2. The two magnetoresistive patterns are provided. In this example, the first magnetoresistive pattern (first-a phase magnetoresistive pattern) R1 located at one end in the relative movement direction, and the third magnetoresistive pattern (second 2-th from the one end). (a-phase magnetoresistive pattern) R3 is a -a-phase magnetoresistive pattern, and the inter-pattern distance between the first magnetoresistive pattern R1 and the third magnetoresistive pattern R3 is 1/4 of the magnetic pole pitch P. . Further, a fifth fifth magnetoresistance pattern (first + a phase magnetoresistance pattern) R5 from one end and a seventh seventh magnetoresistance pattern (second + a phase magnetoresistance pattern) R7 from one end are provided. This is a + a-phase magnetoresistive pattern, and the inter-pattern distance between the fifth magnetoresistive pattern R5 and the seventh magnetoresistive pattern R7 is 1/4 of the magnetic pole pitch P.

  Furthermore, the magnetoresistive pattern for detecting the B phase is -b for detecting the -b phase (-cos phase) and the + b phase (+ cos phase) for detecting the movement of the magnetic scale 2 with a phase difference of 180 °. The magnetoresistive pattern for phase and the magnetoresistive pattern for + b phase are formed, and each of the magnetoresistive pattern for -b phase and the magnetoresistive pattern for + b phase is formed at positions separated from each other in the moving direction of the magnetic scale 2. It has two magnetoresistive patterns. In this example, the second second magnetoresistive pattern (first 1-b phase magnetoresistive pattern) R2 from one end and the fourth fourth magnetoresistive pattern (second 2-b phase use from one end). The magnetoresistive pattern R4 is a -b phase magnetoresistive pattern, and the inter-pattern distance between the second magnetoresistive pattern R2 and the fourth magnetoresistive pattern R4 is 1/4 of the magnetic pole pitch P. Further, the sixth magnetoresistive pattern (first + b phase magnetoresistive pattern) R6 from the one end and the eighth magnetoresistive pattern (second + b phase magnetoresistive pattern) R8 located at the other end are + b. This is a phase magnetoresistive pattern, and the inter-pattern distance between the sixth magnetoresistive pattern R6 and the eighth magnetoresistive pattern R8 is 1/4 of the magnetic pole pitch P.

  FIG. 2 is a circuit diagram of the magnetoresistive patterns R1 to R8 formed on the substrate surface 4a of the sensor substrate 4. As shown in FIG. Each of the magnetoresistive patterns R1 to R8 constitutes a full bridge circuit. More specifically, the first magnetoresistive pattern R1 and the third magnetoresistive pattern R3, which are -a phase magnetoresistive patterns, are connected in series, and the end of the third magnetoresistive pattern R3 is connected to the power supply terminal ( + V), the end on the first magnetoresistive pattern R1 side is connected to the ground terminal, and the -a phase is output from the midpoint position of the first magnetoresistive pattern R1 and the third magnetoresistive pattern R3. The fifth magnetoresistive pattern R5 and the seventh magnetoresistive pattern R7, which are + a phase magnetoresistive patterns, are connected in series, and the end on the side of the fifth magnetoresistive pattern R5 is connected to the power supply terminal (+ V). The end on the seventh magnetic resistance pattern R7 side is connected to the ground terminal, and the + a phase is output from the midpoint position of the fifth magnetic resistance pattern R5 and the seventh magnetic resistance pattern R7. The second magnetoresistive pattern R2 and the fourth magnetoresistive pattern R4 that are -b phase magnetoresistive patterns are connected in series, and the end of the fourth magnetoresistive pattern R4 is connected to the power supply terminal (+ V), The end of the second magnetoresistive pattern R2 side is connected to the ground terminal, and the -b phase is output from the midpoint position of the second magnetoresistive pattern R2 and the fourth magnetoresistive pattern R4. The sixth magnetoresistive pattern R6 and the eighth magnetoresistive pattern R8, which are + b phase magnetoresistive patterns, are connected in series, and the end on the side of the sixth magnetoresistive pattern R6 is connected to the power supply terminal (+ V). The end on the resistance pattern R8 side is connected to the ground terminal, and the + b phase is output from the midpoint position of the sixth magnetoresistive pattern R6 and the eighth magnetoresistive pattern R8.

  The first to eighth magnetoresistive patterns R1 to R8 are all formed from the first folded patterns 14 (1) and 14 (2) and the second folded patterns 24 (1) and 24 (2). The ends of the first to eighth magnetoresistive patterns R1 to R8 are all located on the opposite side of the sensor substrate 4 from the magnetic scale 2. Therefore, it is easy to form a wiring for constituting a full bridge circuit by the first to eighth magnetoresistive patterns R1 to R8 in a region opposite to the magnetic scale 2 of the sensor substrate 4.

  Here, the -a phase (-sin phase) output signal from the midpoint position of the first magnetoresistive pattern R1 and the third magnetoresistive pattern R3 and the fifth magnetoresistive pattern R5 and the seventh magnetoresistive pattern R7. By inputting the + a phase (+ sin phase) output signal from the point position to the subtracter, an A phase output signal having a large amplitude can be obtained from the subtractor. Similarly, the -b phase (-cos phase) output signal from the midpoint position of the second magnetoresistive pattern R2 and the fourth magnetoresistive pattern R4, and the sixth magnetoresistive pattern R6 and the eighth magnetoresistive pattern R8. By inputting the + b phase (+ cos phase) output signal from the point position to the subtracter, a B-phase output signal having a large amplitude can be obtained from the subtractor. Further, the moving position of the magnetic scale 2 can be detected by performing arctangent calculation on the A-phase and B-phase output signals obtained through the subtracters.

(Function and effect)
According to this example, each output signal from the first to eighth magnetoresistive patterns R1 to R8 for detecting the A phase and the B phase is the fundamental wave of the output signal from the fundamental wave detecting magnetoresistive pattern 10. The harmonic component superimposed on the component is reduced or removed.

  FIG. 3A shows first folded patterns 14 (1) and 14 (14) of the fundamental wave detecting magnetoresistive pattern 10 in the first magnetoresistive pattern R1 when the magnetic scale 2 and the magnetic sensor 3 are relatively moved. 2) is a graph showing changes in the resistance values of the first strips 11 and 12, and FIG. 3B is a second folded pattern 24 of the harmonic component removal magnetoresistive pattern 20 in the first magnetoresistive pattern R1. FIG. 3C is a graph showing changes in resistance values of the second strips 21 and 22 of 1) and 24 (2), and FIG. 3C is a resistance value of the magnetoresistance pattern 10 for detecting a fundamental wave shown in FIG. 4 is a graph showing a combined waveform obtained by synthesizing the change in the resistance value and the change in the resistance value of the harmonic component removal magnetoresistive pattern 20 shown in FIG. FIG. 4 is a graph of error in position detection by the linear encoder 1 of this example.

  The change waveform of the resistance value of the fundamental wave detecting magnetoresistive pattern 10 shown in FIG. 3A includes a fundamental wave component and a harmonic component, and is distorted. When a waveform indicating a change in resistance value of the harmonic component removing magnetoresistive pattern 20 shown in FIG. 3B is synthesized with this waveform, a sine wave with less distortion shown in FIG. 3C is obtained. That is, the fundamental wave detecting magnetoresistive pattern 10 and the harmonic component removing magnetoresistive pattern 20 are connected in series, and outputs from the fundamental wave detecting magnetoresistive pattern 10 and the harmonic component removing magnetoresistive pattern 20 are output. When a signal is detected, a sine wave with little distortion is obtained.

  Thus, according to this example, a sine wave output signal with less distortion from which the harmonic component superimposed on the fundamental wave component is removed can be obtained from each of the magnetoresistive patterns R1 to R8. As a result, as shown in FIG. 4, the position detection error by the linear encoder 1 is reduced to 10 μm or less, and the moving position of the magnetic scale 2 can be detected with high accuracy. Therefore, the sensor substrate 4 is disposed in a state where the substrate surface 4a is perpendicular to the magnetic pole surface 2a of the magnetic scale 2 and parallel to the relative movement direction, thereby increasing the gap G between the magnetic sensor 3 and the magnetic scale 2. It becomes possible.

(Comparative example)
FIG. 5A is an explanatory diagram illustrating a schematic configuration of the linear encoder of the comparative example, and FIG. 5B is a circuit diagram of each of the magnetoresistive patterns R1 to R8 of the magnetic sensor 3 of the linear encoder of the comparative example. . 6A is a graph showing a change in the resistance position of the magnetoresistive pattern R1 of the linear encoder of the comparative example, and FIG. 6B is a graph of an error in position detection by the linear encoder of the comparative example.

  In the linear encoder 1A of the comparative example, as shown in FIG. 5A, each of the magnetoresistive patterns R1 to R8 of the magnetic sensor 3 is composed only of the fundamental wave detecting magnetoresistive pattern 10, and each of the magnetoresistive patterns R1. -R8 is not provided with the magnetoresistive pattern 20 for removing harmonic components. Further, in the linear encoder 1 </ b> A of the comparative example, the fundamental wave detecting magnetoresistive pattern 10 is formed by one first folded pattern 14. The linear encoder 1A of the comparative example has the same configuration as that of the linear encoder 1 of the present example except for the configuration of each of the magnetoresistive patterns R1 to R8. Description is omitted.

The waveform of the output signal from the magnetoresistive pattern R1 of the linear encoder 1A of the comparative example is shown in FIG. 6A and is represented by the following approximate expression.
y = G + Asin ((x−xc) π / w) + Bsin ² ((x−xc) π / w)
+ Csin ³ ((x−xc) π / w) + Dsin ⁴ ((x−xc) π / w)
+ Fsin ⁵ ((x−xc) π / w)
A: 4.1199
B: -0.6306
C: 0.1564
D: -1.4825
F: 0.9754
G: 362.2936
xc: 3.6969
w: 2.5151

  When an error in position detection by the linear encoder 1A of the comparative example is simulated based on this approximate expression, an error exceeding 60 μm occurs as shown in FIG. 6B. Therefore, it can be seen that according to the linear encoder 1 of the present invention in which each of the magnetoresistive patterns R1 to R8 includes the harmonic component removing magnetoresistive pattern 20, the position detection accuracy is remarkably improved.

(Modification)
Next, the inventor sets the number of sets of the first and second folded patterns 14 and 24 of the fundamental wave detecting magnetoresistive pattern 10 and the harmonic component removing magnetoresistive pattern 20 between 1 to 4 sets. While changing, the predetermined distance D between the fundamental wave detecting magnetoresistive pattern 10 and the harmonic component removing magnetoresistive pattern 20 was changed to obtain an error in position detection by the linear encoder. FIG. 7 shows the relationship between the fundamental wave detecting magnetoresistive pattern 10 and the harmonic component removing magnetoresistive pattern 20 in each linear encoder in which the number of sets of the first and second folded patterns 14 and 24 is changed to 1 to 4 sets. It is a graph of the error of position detection when changing the predetermined distance D between. FIG. 7A shows a case where the first return pattern 14 of the fundamental wave detecting magnetoresistive pattern 10 and the second return pattern 24 of the harmonic component removing magnetoresistive pattern 20 are each set as one set. ) Shows the case of 2 sets, FIG. 7C shows the case of 3 sets, and FIG. 7D shows the case of 4 sets. 7A to 7D, the predetermined distance D between the fundamental wave detecting magnetoresistive pattern 10 and the harmonic component removing magnetoresistive pattern 20 is between 0.6 mm and 1.0 mm. It is changed with. FIG. 8 is a graph showing the relationship between the position detection error of the linear encoder and the predetermined distance D between the fundamental wave detecting magnetoresistive pattern 10 and the harmonic component removing magnetoresistive pattern 20. In addition, the graph of D = 0.93 of FIG.7 (b) is the same graph as FIG.

  As shown in FIG. 7, the fundamental wave detecting magnetoresistive pattern 10 and the harmonic component removing magnetoresistive pattern 20 regardless of the number of sets of the first and second folded patterns 14 and 24. When the predetermined distance D between 10 and the harmonic component removal magnetoresistive pattern 20 is 0.93 mm, the position detection error by the linear encoder is the smallest. According to the inventor's verification, the number of sets of the first and second folded patterns 14 and 24 is three, and the predetermined distance between the fundamental wave detecting magnetoresistive pattern 10 and the harmonic component removing magnetoresistive pattern 20 is determined. When the distance D was 0.93 mm, the position detection error by the linear encoder was almost zero, and the position detection accuracy was the highest.

Further, as shown in FIG. 8, by setting the predetermined distance D between the fundamental wave detecting magnetoresistive pattern 10 and the harmonic component removing magnetoresistive pattern 20 to the following range, the position detection error by the linear encoder is reduced. It was confirmed that the position could be detected with high accuracy by 10 μm or less.
0.86mm <D <0.98mm

  Here, if the predetermined distance D is set in the above range, the fundamental wave detecting magnetoresistive pattern 10 and the harmonic component removing magnetoresistive pattern 20 are positioned close to each other in the relative movement direction. Accordingly, even when each of the magnetoresistive patterns R1 to R8 is formed at a position adjacent to each other with a pattern distance of 1/8 of the magnetic pole pitch P, the one of the magnetoresistive patterns R1 to R8 is harmonic of one of the magnetoresistive patterns. It can be avoided that the position of the wave component removing magnetoresistive pattern 20 and the position of the fundamental wave detecting magnetoresistive pattern 10 of the other magnetoresistive pattern overlap.

DESCRIPTION OF SYMBOLS 1. Linear encoder, 2. Magnetic scale, 2a, Magnetic pole surface, 3. Magnetic sensor, 4. Sensor board, 4a, Substrate surface, 10. Magnetic resistance pattern for fundamental wave detection, 11, 12, First strip, 13, 1st connecting portion, 14 first folding pattern, 15 first connecting portion, 16 third connecting portion, 20 magnetoresistive pattern for removing harmonic components, 21, 22 second strip portion, 23 second 2 connecting portions, 24 second folding pattern, 25 second connecting portion, D predetermined distance, G gap, P magnetic pole pitch, R1 to R8 first to eighth magnetoresistive patterns

Claims (6)

In a magnetic sensor for detecting relative movement of a linear magnetic scale in which N poles and S poles are alternately arranged at a predetermined magnetic pole pitch,
A sensor substrate whose substrate surface is perpendicular to the magnetic pole surface of the magnetic scale and parallel to the relative movement direction;
A magnetoresistive pattern for detecting a fundamental wave formed on the substrate surface;
In order to remove the harmonic component superimposed on the fundamental wave component of the output signal from the fundamental wave detecting magnetoresistive pattern, the magnetic pole pitch of 1 in the relative movement direction from the fundamental wave detecting magnetoresistive pattern on the substrate surface. A harmonic component removing magnetoresistive pattern formed at a position separated by a predetermined distance shorter than / 8 and connected in series to the fundamental wave detecting magnetoresistive pattern,
The fundamental wave detecting magnetoresistive pattern and the harmonic component removing magnetoresistive pattern have the same shape,
The magnetic sensor according to claim 1, wherein the predetermined distance is in the following range when the magnetic pole pitch is 1.
0.06 ≦ D ≦ 0.10
D: predetermined distance In claim 1 ,
The magnetic sensor according to claim 1, wherein the predetermined distance is in the following range when the magnetic pole pitch is 1.
0.086 <D <0.098
D: predetermined distance In claim 2,
The fundamental wave detecting magnetoresistive pattern includes a pair of rectangular first strips extending in parallel to a direction orthogonal to the magnetic pole surface and the magnetic pole surfaces of the pair of first strips extending in the relative movement direction. Comprising a first folded pattern comprising a first connecting portion connecting the ends on the side,
The harmonic component removing magnetoresistive pattern includes a pair of rectangular second strips extending in a direction perpendicular to the magnetic pole surface and the magnetic poles of the pair of second strips extending in the relative movement direction. A magnetic sensor comprising a second folded pattern comprising a second connecting portion connecting ends on the surface side. In claim 3,
The fundamental wave detecting magnetoresistive pattern includes a plurality of the first folded patterns, and the harmonic component removing magnetoresistive pattern includes the same number of the second folded patterns as the first folded patterns,
The plurality of first folded patterns are connected in series,
The plurality of second folded patterns are connected in series. In any one of claims 1 to 4,
A magnetic resistance pattern for A phase and a magnetic resistance pattern for B phase formed on the surface of the substrate to detect A phase and B phase, which detect the movement of the magnetic scale with a phase difference of 90 ° from each other;
The A-phase magnetoresistive pattern includes a + a-phase magnetoresistive pattern and a -a-phase magnetoresistive pattern for detecting movement of a magnetic scale with a phase difference of 180 °,
The B phase magnetoresistive pattern includes a + b phase magnetoresistive pattern and a -b phase magnetoresistive pattern for detecting movement of a magnetic scale with a phase difference of 180 °,
The + a phase magnetoresistive pattern includes first and second + a phase magnetoresistive patterns formed at positions separated from each other in the relative movement direction,
As the -a phase magnetoresistive pattern, provided with a first and a 2-a phase magnetoresistive pattern formed at positions separated from each other in the relative movement direction,
The + b phase magnetoresistive pattern includes first and second + b phase magnetoresistive patterns formed at positions separated from each other in the relative movement direction,
As the -b phase magnetoresistive pattern, provided with first and second b phase magnetoresistive patterns formed at positions separated from each other in the relative movement direction,
The first and second + a phase magnetoresistive patterns, the first and second 2-a phase magnetoresistive patterns, the first and second + b phase magnetoresistive patterns, and the first and second b phases Each of the magnetoresistive patterns comprises the fundamental wave detecting magnetoresistive pattern and the harmonic component removing magnetoresistive pattern,
The first and second + a phase magnetoresistive patterns, the first and second 2-a phase magnetoresistive patterns, the first and second + b phase magnetoresistive patterns, and the first and second b phases The magnetic sensor, wherein the magnetoresistive pattern forms a full bridge circuit. A magnetic sensor according to any one of claims 1 to 5;
A linear encoder having a linear magnetic scale in which N poles and S poles are alternately arranged at the magnetic pole pitch.

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