JP2005249774A - Magnetic sensor and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic sensor capable of preventing a degree of arrangement freedom from getting low caused by narrowing of a space between magnetoresistor thin films, when using the plurality of magnetoresistor thin films in view point of enhancing discrimination precision, in an operation of the magnetic sensor. <P>SOLUTION: In this magnetic sensor having a magnetoresistant pattern with the magnetoresistor thin films formed on a substrate, wherein the magnetoresistant pattern is constituted of an A-phase magnetoresistant pattern and a B-phase magnetoresistant pattern for outputting two signals different in phases by 90°, the magnetoresistant pattern is formed by combining the two substrates. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a magnetic sensor for detecting a displacement amount such as a moving amount, a position, and an angle of a movable detection object, and a manufacturing method thereof, and in particular, a magnetoresistive formed in a magnetoresistive pattern included in the magnetic sensor. The present invention relates to a magnetic sensor capable of increasing the degree of freedom of arrangement of a body thin film and a method for manufacturing the same.

  Conventionally, there is a magnetic sensor as a sensor for detecting the amount of displacement of a movable object. As one aspect of this magnetic sensor, for example, a multipolar magnetic layer magnetized at a constant pitch is formed on a movable object to be detected, and a magnetic sensor is disposed opposite to the multipolar magnetic layer, In this magnetic sensor, four magnetoresistive thin films (magnetoresistance elements) are arranged at a pitch narrower than the pitch of multipolar magnetization, and the resistance value of the magnetoresistive thin film that changes due to the rotation of the movable object to be detected The amount of displacement is detected by detecting.

  In recent years, an output signal from a magnetic sensor is generally formed of a fundamental wave component and a harmonic component superimposed on the fundamental wave component. A technique for improving the identification accuracy by removing the harmonic component and obtaining a smooth output signal like the fundamental component has appeared (for example, see Patent Document 1).

  According to the invention disclosed in Patent Document 1, when a magnetoresistive thin film is arranged on a magnetic sensor arranged to face a multipolar magnetized layer, a plurality of the magnetoresistive thin films are arranged at predetermined intervals. By doing so, the harmonic component caused by the saturation of the magnetoresistive change is canceled out in the opposite phase and canceled out, and as a result, a smooth sine wave output signal can be obtained.

  On the other hand, when a magnetic scale magnetic field is detected by a plurality of magnetoresistive thin films, all of these magnetoresistive thin films are generally arranged on a single glass substrate. For example, as disclosed in Patent Document 2, all of the plurality of magnetoresistive thin films are mounted on a magnetoresistive element mounting portion mounted along a positioning guide of the holder.

Japanese Patent No. 2529960 (FIG. 2) Japanese Patent Laid-Open No. 10-253729 (FIG. 1)

  However, when a plurality of magnetoresistive thin films are arranged on one glass substrate in order to cancel the harmonic components of the output signal and improve the identification accuracy, there is a gap between the magnetoresistive thin films. There exists a problem that it becomes very narrow and it becomes difficult to arrange | position in a desired position.

  In particular, in a magnetic sensor composed of an A-phase magnetoresistive pattern and a B-phase magnetoresistive pattern that outputs two signals that are 90 ° out of phase, each magnetoresistive pattern has a plurality of magnetic resistance patterns in order to improve identification accuracy. When the resistor thin film is provided, the manufacturing difficulty is further increased, and as a result, there is a problem that the degree of freedom in arranging the magnetoresistive thin film is lowered.

  The present invention has been made in view of the above points, and its purpose is to use a plurality of magnetoresistive thin films from the viewpoint of improving identification accuracy when operating a magnetic sensor. An object of the present invention is to provide a magnetic sensor capable of preventing a reduction in the degree of freedom in arrangement due to the narrowing of the interval between body thin films.

  In order to solve the above problems, the present invention provides the following.

  (1) A magnetoresistive thin film has a magnetoresistive pattern formed on a substrate, and the magnetoresistive pattern includes an A phase magnetoresistive pattern and a B phase magnetoresistive pattern that output two signals having a 90 ° phase difference. The magnetic sensor is characterized in that the magnetoresistive pattern is formed by combining two substrates.

  According to the present invention, in a magnetic sensor having a magnetoresistive pattern, the magnetoresistive pattern is formed by combining two substrates. Therefore, a plurality of magnetoresistive thin films are used from the viewpoint of improving identification accuracy. Even in this case, it is not necessary to extremely narrow the interval between the magnetoresistive thin film and the magnetoresistive thin film, and as a result, it is possible to prevent a reduction in the degree of freedom in arrangement due to the narrowing of the interval.

  Here, when “two substrates are combined”, they may be combined in close contact, or may be combined with a gap.

  (2) The magnetic sensor according to (1), wherein the A-phase magnetoresistive pattern and the B-phase magnetoresistive pattern are formed on different substrates, respectively.

  According to the present invention, since the A-phase magnetoresistive pattern and the B-phase magnetoresistive pattern described above are formed on different substrates, respectively, each of the A-phase magnetoresistive pattern and the B-phase magnetoresistive pattern. In these magnetoresistive patterns, it is possible to prevent the interval between the magnetoresistive thin film and the magnetoresistive thin film from becoming narrow, and to prevent a reduction in the degree of freedom in arrangement due to the narrowing.

  (3) The A-phase magnetoresistive pattern is composed of a + a-phase magnetoresistive pattern and a -a-phase magnetoresistive pattern that outputs two signals having a phase difference of 180 °, and the B-phase magnetoresistive pattern is 180 ° -phase. The + b phase magnetoresistive pattern and the −b phase magnetoresistive pattern for outputting two signals different from each other, and the + a phase magnetoresistive pattern and the −b phase magnetoresistive pattern are formed on one substrate. The magnetic sensor according to (1), wherein the -a phase magnetoresistive pattern and the + b phase magnetoresistive pattern are respectively formed on the other substrate.

  According to the present invention, the A-phase magnetoresistive pattern described above is composed of a + a-phase magnetoresistive pattern that outputs two signals that are 180 ° out of phase and a -a-phase magnetoresistive pattern, and the B-phase magnetoresistive pattern described above. The pattern is composed of a + b phase magnetoresistive pattern and a −b phase magnetoresistive pattern that output two signals having different phases by 180 °, and among these magnetoresistive patterns, a + a phase magnetoresistive pattern and −b phase Since the phase magnetoresistive pattern is formed on one substrate and the -a phase magnetoresistive pattern and the + b phase magnetoresistive pattern are formed on the other substrate, respectively, the degree of freedom in arrangement due to the narrowing of the interval is reduced. In addition to being able to prevent, it is possible to improve detection accuracy and distance characteristics.

  In other words, the substrate on which the magnetoresistive thin film is formed generally varies from lot to lot due to various factors such as the deposition temperature, the deposition time, and the relative positional relationship between the target and the substrate. According to the invention, the A-phase magnetoresistive pattern is divided into two substrates, and the B-phase magnetoresistive pattern is also divided into two substrates. Both the resistance pattern and the B-phase magnetoresistive pattern will be affected uniformly, and as a result, the adverse effects due to variations in the characteristics of the two substrates can be reduced as a whole, with the result that detection accuracy is improved and distance characteristics are improved. Improvements can be made.

  (4) The magnetic sensor according to (3), wherein the one substrate and the other substrate are made of different materials.

  According to the present invention, the material of the substrate of the one substrate described above and the other substrate described above are different, but even in such a case, the adverse effect due to variation in two different substrate characteristics as a whole. As a result, it is possible to improve detection accuracy and distance characteristics.

  (5) The magnetic sensor according to any one of (1) to (4), wherein the pattern formation surfaces of the two substrates are bonded together.

  According to the present invention, since the pattern forming surfaces of the two substrates described above are bonded together, the influence of external temperature change can be reduced, and stable temperature characteristics can be obtained. .

  (6) All or part of one pattern formation surface of the two substrates and part of the other pattern formation surface of the two substrates are bonded to each other (5) The magnetic sensor described.

  According to the present invention, all or part of one pattern formation surface of the two substrates described above and part of the other pattern formation surface of the two substrates described above are bonded together. Therefore, the bonding position can be adjusted flexibly according to the arrangement mode of the magnetoresistive thin film on each pattern formation surface, and consequently the interval between the magnetoresistive thin films can be prevented from being narrowed. Further, using a flexible circuit board or the like, it becomes possible to take out a signal from a pattern formation surface that is not a bonding surface.

  (7) The magnetoresistive thin film has a magnetoresistive pattern formed on the substrate, and the magnetoresistive pattern includes an A-phase magnetoresistive pattern and a B-phase magnetoresistive pattern that output two signals having a 90 ° phase difference. In the manufacturing method of manufacturing a magnetic sensor comprising the following: forming the magnetoresistive pattern by combining the two substrates after forming the magnetoresistive pattern on the two substrates A method of manufacturing a magnetic sensor.

  According to the present invention, in a method of manufacturing a magnetic sensor having a magnetoresistive pattern, the magnetoresistive pattern is formed by combining the two substrates after the magnetoresistive pattern is formed on the two substrates. As a result, it is possible to prevent a decrease in the degree of freedom in arrangement due to the narrowing of the interval.

  As described above, in the magnetic sensor and the manufacturing method thereof according to the present invention, since the magnetoresistive pattern is formed by combining two substrates, a plurality of elements are used from the viewpoint of canceling harmonic components and improving identification accuracy. Even if the magnetoresistive thin film is used, the number of magnetoresistive thin films formed on one set of substrates can be reduced, and the arrangement due to the narrowing of the interval between the magnetoresistive thin films. A reduction in the degree of freedom can be prevented.

  For the purpose of improving temperature characteristics, a magnetoresistive pattern composed of an A-phase magnetoresistive pattern and two B-phase magnetoresistive patterns that output two signals having a phase difference of 90 ° is Since the pattern is divided into two substrates and the B-phase magnetoresistive pattern is also divided into two substrates, adverse effects due to variations in the characteristics of the two substrates can be reduced, and as a result, detection accuracy is improved. And distance characteristics can be improved.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

[Magnetic sensor structure]
FIG. 1A is an external view showing a facing arrangement relationship between the magnetic sensor 1 and the movable object to be detected according to the first embodiment of the present invention.

  In FIG. 1 (a), a rotating drum 2 as a movable object to be detected is rotatable about a rotation axis, and N and S poles are alternately arranged at a predetermined pitch on the outer periphery thereof. A magnetic scale 3 is provided. The magnetic scale 3 is formed, for example, by magnetizing a magnetic pole on a ferromagnetic material. On the other hand, the magnetic sensor 1 is disposed to face the magnetic scale 3.

  Here, in order to clarify the difference in structure from the prior art, the structure of the conventional magnetic sensor 1 having the same facing arrangement relationship as in FIG. FIG. 1B is a plan view of the conventional magnetic sensor 1 and the rotating drum 2 as viewed from above.

  In FIG. 1B, a conventional magnetic sensor 1 has a glass substrate 5 fixed to a printed wiring board PWB (Printed Wiring Board) 4, and a magnetoresistive pattern 6 is formed on the glass substrate 5. Since the magnetoresistive pattern 6 is very sensitive to temperature changes and has a property that the temperature characteristics change even when it is blown by wind, the magnetoresistive pattern 6 is provided around the magnetoresistive pattern 6. It is common to provide a protective plate (not shown) for covering.

  The magnetoresistive pattern 6 is an A-phase magnetoresistive pattern that outputs two signals that are 90 ° out of phase and B in order to accurately detect the amount and direction of displacement of the movable object 2 (magnetic scale 3). The magnetoresistive pattern is formed on the glass substrate 5. Therefore, when each of the A-phase magnetoresistive pattern and the B-phase magnetoresistive pattern has a plurality of magnetoresistive thin films, the space between the magnetoresistive thin films is narrowed, so It was causing a decline.

  FIG. 2 is a plan view of the magnetic sensor 1 and the rotating drum 2 according to the first embodiment of the present invention as viewed from above.

  In FIG. 2, the magnetic sensor 1 according to the first embodiment of the present invention includes a printed wiring board PWB4 in which wiring is pasted with copper foil to an insulating board (insulating material such as epoxy resin) having a thickness of about several mm. Two glass substrates 5, 5 ', an A phase magnetoresistive pattern 10 formed on the lower glass substrate (A phase substrate) 5 in the figure, and an upper glass substrate (for B phase in the figure) Substrate) B-phase magnetoresistive pattern 11 formed on 5 ′, adhesive material 12 for bonding two glass substrates 5, 5 ′, and magnetoresistor for fixing two glass substrates 5, 5 ′ A flexible circuit board FPC (Flexible Printed Circuit) 14 which is taken out as an electrode from the end of the thin film fixing base 13 and the glass substrates 5 and 5 ′ and used for connection with the printed wiring board PWB, a case 15, Consists of. The glass substrates 5 and 5 ′ on which the A-phase magnetoresistive pattern 10 and the B-phase magnetoresistive pattern 11 are formed can be replaced with a ceramic such as zirconia in order to prevent damage due to external impact. .

  Here, the magnetic sensor 1 shown in FIG. 2 is greatly different from the magnetic sensor 1 shown in FIG. 1B in that the A-phase magnetoresistive pattern 10 and the B-phase are respectively formed on the two glass substrates 5 and 5 ′. The magnetoresistive pattern 11 is formed separately by vapor deposition or the like. According to such a structure, even if each of the A-phase magnetoresistive pattern 10 and the B-phase magnetoresistive pattern 11 has a plurality of magnetoresistive thin films, only one glass substrate is provided. Compared with the magnetic sensor 1 shown in FIG. 3), it is possible to prevent the interval between the magnetoresistive thin films from being narrowed, and thus to prevent the degree of freedom in arrangement between the magnetoresistive thin films.

[Manufacturing process]
FIG. 3 is an explanatory diagram of a method for manufacturing the two glass substrates 5 and 5 ′, which is a characteristic part of the magnetic sensor 1 according to the first embodiment of the invention.

  In FIG. 3, first, a plurality of magnetoresistive thin films made of ferromagnetic material NiFe or the like are formed on the A-phase substrate 5 as an A-phase magnetoresistive pattern 10 by vapor deposition or the like (FIG. 3A). Further, a plurality of magnetoresistive thin films made of ferromagnetic NiFe or the like are formed as a B phase magnetoresistive pattern 11 on the B phase glass substrate 5 ′ by vapor deposition or the like (FIG. 3B). The magnetoresistive thin film (FIG. 3A) of the A-phase magnetoresistive pattern 10 formed on the A-phase glass substrate 5 is also the B-phase formed on the B-phase glass substrate 5 ′. The magnetoresistive thin film (FIG. 3B) included in the magnetoresistive pattern 11 also has a differential configuration in order to improve temperature characteristics. Further, in order to remove the harmonic component superimposed on the fundamental wave component of the output signal, a plurality of magnetoresistive thin films are disposed on each of the glass substrate 5 for A phase and the glass substrate 5 'for B phase. However, in the magnetic sensor 1 according to the present embodiment, since the magnetoresistive pattern is formed by bonding the glass substrate 5 for A phase and the glass substrate 5 ′ for B phase, as a result, each magnetoresistive Narrowing of the space between the body thin films can be prevented.

  Finally, the A-phase magnetoresistive pattern 10 and the B-phase magnetoresistive pattern 11 are bonded so as to face each other (FIG. 3C). Thereby, since each magnetoresistive pattern will be formed on separate glass substrates 5 and 5 ', the space | interval between each magnetoresistive thin film can be prevented from narrowing. Further, since the A-phase magnetoresistive pattern 10 and the B-phase magnetoresistive pattern 11 are sandwiched between the glass substrates 5 and 5 ′, it is resistant to external impacts and the like, and thus it is unnecessary to mount components such as a protective plate. Can do. An insulating film exists between the A-phase magnetoresistive pattern 10 and the B-phase magnetoresistive pattern 11.

  Here, since the magnetic sensor 1 according to the present embodiment is bonded so that the magnetoresistive patterns face each other, it does not react sensitively to a sudden change in the external temperature, and obtains stable temperature characteristics. be able to. More specifically, a description will be given with reference to FIG. FIG. 4 is a graph showing the time-series sensor output of the magnetic sensor 1 according to the first embodiment of the invention.

  In FIG. 4, in the conventional magnetic sensor 1 (see FIG. 1B), even in the constant temperature layer, for example, when the temperature changes from −20 ° C. to 70 ° C., it is over like the X portion in FIG. A shoot occurs. This is usually due to the fact that a differential output is obtained to improve the temperature characteristics of the magnetoresistive thin film, but it does not result in a uniform temperature distribution when the temperature changes rapidly. However, according to the magnetic sensor 1 (see FIG. 2) according to the present embodiment, the magnetoresistive pattern is formed via the two glass substrates 5 and 5 ′ (between the two glass substrates 5 and 5 ′). Since it exists, the overshoot of the X portion in FIG. 4 can be reduced as in the Y portion in FIG. 4, thereby contributing to stable temperature characteristics.

  In FIG. 3C, the A-phase magnetoresistive pattern 10 and the B-phase magnetoresistive pattern 11 are stuck together (closely adhered), but the present invention eliminates the gap between them. It is not the purpose. In FIG. 3C, a part of the A-phase magnetoresistive pattern 10 (pattern forming surface) formed on the A-phase glass substrate 5 and the B-phase glass substrate 5 ′ are formed. A part of the B-phase magnetoresistive pattern 11 (pattern forming surface) is bonded together. For example, all of the A-phase magnetoresistive pattern 10 or the B-phase magnetoresistive pattern 11 and the A-phase magnetoresistive pattern 10 are combined. Alternatively, all or a part of the other side of the B-phase magnetoresistive pattern 11 may be bonded.

[Modification]
FIG. 5 is an explanatory diagram for explaining the characteristic part of the magnetic sensor 1 according to the second embodiment of the present invention. 5A and 5C are a cross-sectional view of the characteristic part of the magnetic sensor 1 according to the first embodiment of the present invention and a schematic diagram for explaining the characteristic part. FIG. 5B and FIG. 5D are a cross-sectional view of the characteristic part of the magnetic sensor 1 according to the second embodiment of the present invention and a schematic diagram for explaining the characteristic part.

In FIG. 5 (a), the magnetic sensor 1 according to the first embodiment of the present invention is characterized in that the glass substrate 5 for A phase and the glass substrate 5 'for B phase are bonded together as described above. Two cosine waves (Cos ⁺ , Cos ⁻ ) that are 180 ° out of phase are extracted from the A-phase magnetoresistive pattern 10 formed on the A-phase glass substrate 5, and the B-phase glass substrate is extracted. Two sine waves (Sin ⁺ , Sin ⁻ ) that are 180 ° out of phase are extracted from the B-phase magnetoresistive pattern 11 formed 5 ′.

  That is, in FIG. 5C, in the characteristic part of the magnetic sensor 1 according to the first embodiment of the present invention, two signals (+ a phase signal and −a phase signal) whose phases are shifted by 180 ° are Two signals (+ b phase signal and -b phase signal) detected by the A phase magnetoresistive pattern 10 arranged at predetermined intervals on the glass substrate 5 for A phase and having a phase difference of 180 ° are used for the B phase. It is detected from the B-phase magnetoresistive pattern 11 arranged on the glass substrate 5 ′ at a predetermined interval.

On the other hand, in FIG. 5B, in the characteristic part of the magnetic sensor 1 according to the second embodiment of the present invention, two glass substrates not specifically defined for the A phase or the B phase are bonded together. A cosine wave (Cos ⁺ ) and a sine wave (Sin ⁻ ) whose phases are shifted by 90 ° are extracted from the magnetoresistive pattern formed on the lower glass substrate, and the magnetoresistive formed on the upper glass substrate. A cosine wave (Cos ⁻ ) and a sine wave (Sin ⁺ ) whose phase is shifted by 90 ° are extracted from the pattern.

  That is, in FIG. 5D, in the characteristic part of the magnetic sensor 1 according to the second embodiment of the present invention, two signals (+ a phase signal, −a phase signal) whose phases are shifted by 180 ° are Two signals (+ b phase signal and -b phase signal) detected from the magnetoresistive pattern divided into two glass substrates and shifted in phase by 180 ° are also divided into two glass substrates. Detected from.

  In this way, by detecting two signals that are 180 ° out of phase from the magnetoresistive pattern divided into two glass substrates, even if there are variations in the characteristics of the two glass substrates, Can be reduced, and as a result, detection accuracy and distance characteristics can be improved. In addition, for example, when one is a glass substrate and the other is an aluminum substrate, or when one is a glass substrate and the other is zirconia, even when the materials of the two substrates are changed, detection is performed as described above. It is possible to improve accuracy and improve distance characteristics.

  FIG. 6 is a waveform diagram showing how the adverse effect caused by the characteristic variation of two glass substrates is reduced in the magnetic sensor 1 according to the second embodiment of the present invention. More specifically, the amplitude of the signal detected from the magnetoresistive thin film formed on one glass substrate due to the characteristic variation of the two glass substrates causes the magnetoresistor formed on the other glass substrate. When the amplitude of the signal detected from the thin film is larger than that of the magnetic sensor 1 according to the first embodiment of the present invention, the adverse effect cannot be reduced (FIG. 6 (a)). According to the magnetic sensor 1 according to the second embodiment, the adverse effect can be reduced (FIG. 6B).

  First, the case where the amplitude of the signal detected from the B-phase magnetoresistive pattern 11 formed on the B-phase glass substrate 5 ′ in FIG. The amplitudes of the + a phase signal and the −a phase signal (see FIG. 5C) detected from the A phase magnetoresistive pattern 10 are both 1 (the first and second stages from the top). Accordingly, the amplitude of the A-phase differential output obtained by subtracting the -a phase signal from the + a phase signal is 2 (third stage from the top). On the other hand, the amplitudes of the + b phase signal and the −b phase signal (see FIG. 5C) detected from the B phase magnetoresistive pattern 11 are both 0.8 (fourth and fifth stages from the top). Therefore, the amplitude of the B-phase differential output obtained by subtracting the -b phase signal from the + b phase signal is 1.6 (sixth stage from the top).

  As described above, in the magnetic sensor 1 according to the first embodiment of the present invention, the amplitude of the A-phase differential output (= 2) and the amplitude of the B-phase differential output (= 2) due to the characteristic variation of the two glass substrates. = 1.6) may cause a difference.

  Next, the case where the amplitude of the signal detected from the magnetoresistive pattern formed on the upper glass substrate in FIG. The amplitudes of the + a phase signal and the −b phase signal (see FIG. 5D) detected from the lower magnetoresistive pattern are both 1 (first and fifth stages from the top). On the other hand, the amplitudes of the −a phase signal and the + b phase signal (see FIG. 5D) detected from the upper magnetoresistive pattern are both 0.8 (second and fourth stages from the top). Accordingly, the amplitude of the A phase differential output obtained by subtracting the −a phase signal from the + a phase signal is 1.8 (third stage from the top), and the amplitude of the B phase differential output obtained by subtracting the −b phase signal from the + b phase signal is also 1.8 (sixth stage from the top), and the amplitudes of both outputs match.

  As described above, in the magnetic sensor 1 according to the second embodiment of the present invention, the differential output between the A phase and the B phase is detected even when the characteristic variation of the two glass substrates occurs. Thus, the adverse effect can be reduced.

FIG. 6 shows a state in which the adverse effect due to the characteristic variation of the two glass substrates is reduced. For example, as shown in FIG. 7B, the two glass substrates are inclined due to a mounting error. In this case, the adverse effects in the case can be reduced. More specifically, first, the correct mounting state of the two glass substrates is a state parallel to the magnetic scale 3 (FIG. 7 (a)). Suppose that it leans to the left (FIG. 7B). At this time, the magnetoresistive pattern (see FIG. 5D) capable of detecting the + a phase signal (Cos ⁺ ) and the −b phase signal (Sin ⁻ ) approaches the magnetic scale 2, and the −a phase signal (Cos ⁻ ) The magnetoresistive pattern (see FIG. 5D) that can detect the + b phase signal (Sin ⁺ ) is moved away from the magnetic scale 2. Then, the amplitudes of the + a phase signal and the −b phase signal become larger than usual, while the amplitudes of the −a phase signal and the + b phase signal become smaller than usual. As a result, as described above with reference to FIG. 6B, the adverse effects can be reduced at the stage of detecting the differential outputs of the A phase and the B phase.

  FIG. 8 is a waveform diagram showing how the adverse effect caused by the bonding error between two glass substrates is reduced in the magnetic sensor 1 according to the second embodiment of the present invention. More specifically, due to an error in bonding two glass substrates, the two glass substrates are not bonded in an appropriate positional relationship, and are detected from a magnetoresistive thin film formed by one glass substrate. The magnetic sensor according to the first embodiment of the present invention when the phase of the detected signal is inappropriate in relation to the phase of the signal detected from the magnetoresistive thin film formed by the other glass substrate 1, the adverse effect cannot be reduced (FIG. 8A), but the magnetic sensor 1 according to the second embodiment of the present invention shows that the adverse effect can be reduced. (FIG. 8B).

  First, in FIG. 8A, the case where the phase of the signal detected from the B-phase magnetoresistive pattern 11 formed on the glass substrate 5 ′ for B-phase is slightly shifted will be described. There is no deviation in the phases of the + a phase signal and the -a phase signal (see FIG. 5C) detected from the A phase magnetoresistive pattern 10, and the phase of the A phase differential output obtained by subtracting the -a phase signal from the + a phase signal. Not shifted (1st to 3rd steps from the top). However, the phase of the + b phase signal and the −b phase signal (see FIG. 5C) detected from the B phase magnetoresistive pattern 11 is an ideal phase (due to a bonding error between two glass substrates). The phase is slightly shifted from the ideal state (the fourth line from the top and the fifth solid line), not the fourth and fifth lines from the top. As a result, the phase of the B-phase differential output obtained by subtracting the −b phase signal from the + b phase signal is not an ideal phase (the dotted line at the sixth stage from the top), but a phase slightly shifted from the ideal state (the six stages from the top). (Solid line of eyes).

  Here, in general, when detecting the position of a movable detection object, a magnetic sensor performs position detection by obtaining an arctangent signal from an A-phase differential output (cosine wave) and a B-phase differential output (sine wave). ing. That is, if the phase of either the A-phase differential output or the B-phase differential output deviates from the ideal state (B-phase differential output in FIG. 8A), accurate position detection cannot be performed.

  As described above, in the magnetic sensor 1 according to the first embodiment of the present invention, the phase of either the A-phase differential output or the B-phase differential output is shifted due to the bonding error between the two glass substrates. As a result, the accuracy of position detection may be reduced.

  Next, the case where the phase of the signal detected from the magnetoresistive pattern formed on the upper glass substrate is slightly shifted in FIG. 8B will be described. There is no deviation in the phases of the + a phase signal and the -b phase signal (see FIG. 5D) detected from the lower magnetoresistive pattern (first and fifth stages from the top). On the other hand, the phases of the −a phase signal and the + b phase signal (see FIG. 5D) detected from the upper magnetoresistive pattern are not ideal phases (the dotted lines in the second and fourth stages from the top), The phase is slightly shifted from the ideal state (the second and fourth solid lines from the top). As a result, both the A phase differential output obtained by subtracting the −a phase signal from the + a phase signal and the B phase differential output obtained by subtracting the −b phase signal from the + b phase signal are both ideal phases (3, 6 from the top). It is not a stage (dotted line) but a phase slightly shifted from the ideal state (solid lines at the third and sixth stages from the top).

  However, as described above, since the position detection is performed by obtaining an arctangent signal in a general magnetic sensor, when the phases of both the A-phase differential output and the B-phase differential output are shifted in the same manner, Does not affect the accuracy of position detection. Therefore, in the magnetic sensor 1 according to the second embodiment of the present invention, even if a bonding error occurs between the two glass substrates, the differential output of the A phase and the B phase is detected, and the reverse At the stage of obtaining the tangent signal, it is possible to reduce the adverse effect thereof and to prevent a decrease in position detection accuracy.

  In the magnetic sensor according to the present invention, when the magnetoresistive pattern has a plurality of magnetoresistive thin films, it is possible to prevent a decrease in the degree of freedom in arrangement due to the narrowing of the interval between the respective magnetoresistive thin films. Useful.

(A) It is an external view which shows the opposing arrangement | positioning relationship of the magnetic sensor which concerns on embodiment of this invention, and a movable to-be-detected object. (B) It is the top view which looked at the conventional magnetic sensor and rotary drum from the top. It is the top view which looked at the magnetic sensor and rotary drum which concern on embodiment of this invention from the top. It is explanatory drawing about the manufacturing method of two glass substrates which are the characterizing parts of the magnetic sensor which concerns on embodiment of this invention. It is a graph which shows the time series sensor output of the magnetic sensor which concerns on embodiment of this invention. It is explanatory drawing for demonstrating the characteristic part of the magnetic sensor which concerns on the 2nd Embodiment of this invention. It is a wave form diagram which shows a mode that the bad influence resulting from the characteristic variation of two glass substrates is reduced in the magnetic sensor which concerns on the 2nd Embodiment of this invention. It is an external view for demonstrating the attachment state of two glass substrates. It is a wave form diagram which shows a mode that the bad influence resulting from the bonding error of two glass substrates is reduced in the magnetic sensor which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

1 Magnetic Sensor 2 Rotating Drum 3 Magnetic Scale 4 PWB
5, 5 'Glass substrate 10 A phase magnetoresistive pattern 11 B phase magnetoresistive pattern 12 Adhesive material 13 Magnetoresistive thin film fixing base 14 FPC
15 cases

Claims (7)

The magnetoresistive thin film has a magnetoresistive pattern formed on a substrate, and the magnetoresistive pattern is composed of an A-phase magnetoresistive pattern and a B-phase magnetoresistive pattern that output two signals that are 90 ° out of phase. In the magnetic sensor
2. The magnetic sensor according to claim 1, wherein the magnetoresistive pattern is formed by combining two substrates.   2. The magnetic sensor according to claim 1, wherein the A-phase magnetoresistive pattern and the B-phase magnetoresistive pattern are formed on different substrates, respectively. The A-phase magnetoresistive pattern is composed of a + a-phase magnetoresistive pattern and -a-phase magnetoresistive pattern that outputs two signals having a phase difference of 180 °,
The B phase magnetoresistive pattern is composed of a + b phase magnetoresistive pattern that outputs two signals that are 180 ° out of phase and the -b phase magnetoresistive pattern,
The + a phase magnetoresistive pattern and the -b phase magnetoresistive pattern are formed on one substrate, and the -a phase magnetoresistive pattern and the + b phase magnetoresistive pattern are formed on the other substrate, respectively. The magnetic sensor according to claim 1.   4. The magnetic sensor according to claim 3, wherein the one substrate and the other substrate are made of different materials.   5. The magnetic sensor according to claim 1, wherein the pattern forming surfaces of the two substrates are bonded to each other.   6. The magnetism according to claim 5, wherein all or a part of one pattern forming surface of the two substrates and a part of the other pattern forming surface of the two substrates are bonded together. Sensor. The magnetoresistive thin film has a magnetoresistive pattern formed on a substrate, and the magnetoresistive pattern is composed of an A-phase magnetoresistive pattern and a B-phase magnetoresistive pattern that output two signals that are 90 ° out of phase. In a manufacturing method for manufacturing a magnetic sensor,
A method of manufacturing a magnetic sensor, comprising: forming the magnetoresistive pattern by combining the two substrates after forming the magnetoresistive pattern on two substrates.

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