JP4487252B2 - Magnetic position rotation detection element - Google Patents

Description

  The present invention relates to a magnetic position rotation detection device using a magnetoresistive effect element, which is used for a machine tool, an electronic device, and the like.

  2. Description of the Related Art Conventionally, a magnetic position rotation detection device used for a machine tool or the like has a magnetic medium in which N poles and S poles are alternately and alternately magnetized at a predetermined interval, and a thin film ferromagnetic such as Fe-Ni (permalloy). And a magnetic sensing element using the magnetoresistive effect of the body. In recent years, an artificial lattice magnetoresistive element (hereinafter referred to as a GMR element) in which a large number of magnetic layers and nonmagnetic layers are alternately stacked has been used as a magnetic detection element having a large resistance change with respect to a magnetic field. The resolution is progressing.

  The GMR element has a feature that the shape anisotropy is small, the magnetosensitive axis causing the magnetoresistance change is relatively isotropic, and the sensitivity is particularly high with respect to the magnetic field in the longitudinal direction of the rectangular pattern. For this reason, a magnetic sensing element has been devised in which a large number of patterns smaller than the magnetization pitch λ are arranged in the direction of the magnetic field and connected in series in a space that receives a substantially constant magnetic field from the medium, and further connected in series. Yes. Usually, the relative movement direction of the magnetic medium and the magnetic detection element is determined by arranging another pattern of the magnetic detection element so that the bridge circuit has a phase difference of 90 degrees in the movement direction of the medium. It is possible to do.

  As the level of positioning accuracy required for a machine tool increases, the position rotation detection element is also required to have high resolution and high accuracy. Higher resolution and higher accuracy of the position rotation detection element can be realized by reducing the magnetization pitch of the magnetic pattern and reducing distortion of the output waveform. For example, when the magnetization pitch is reduced, the gap between the magnetized medium and the detection element is usually reduced accordingly. However, it is difficult to keep the gap relatively constant as the pitch decreases. On the other hand, a method for obtaining high output by using an artificial lattice film as a magnetosensitive element is disclosed (Patent Document 1). In order to improve the resolution, one period of the output waveform may be interpolated and multiplied for use. In that case, it is desirable that the output waveform has a sine wave shape with less harmonic distortion. For example, when a signal obtained from one pattern is set to a phase of 0 degree, this antiphase (180 degrees different) is obtained. By taking the differential output with the output, even-order harmonics are canceled out. Furthermore, a specific harmonic component is removed using the concept of a spatial filter. In this way, the output waveform contains as little harmonic components as possible. However, since the magnetoresistive element and the artificial lattice GMR have a non-linear resistance change with respect to the applied magnetic field, it is difficult to obtain a sine wave. Further, various methods for obtaining a sinusoidal output regardless of the gap have been devised (Patent Documents 2 and 3). Also disclosed is a configuration in which a plurality of magnetoresistive elements are arranged at predetermined intervals in the relative movement direction in order to prevent deterioration in accuracy with respect to partial recording state fluctuations of the recording medium and temperature fluctuations of the detecting means. (Patent Document 4).

Japanese Patent No. 3067484 JP-A-11-148841 JP 2001-141514 A JP-A-8-122095

  Machine tools and office automation equipment require small, high-resolution magnetic scales and magnetic sensing elements, but this is not affected by large mounting tolerances when mounting on equipment, disturbance magnetic fields, temperature fluctuations, etc. High reliability and stability are required. The magnetic detection element disclosed in Patent Document 1 uses an artificial lattice film as a magnetosensitive element and obtains a large output signal. However, the area of the artificial lattice film is small compared to the element area, and the element area However, it is difficult to detect the magnetic field from the magnetic medium over a wide area, and it is easy to pick up partial fluctuations in the magnetic state. In Patent Document 4, it is also devised that the magnetic field detection portions are arranged in a wide area. The advantage of detecting a magnetic field over a large area is that it has the effect of spatially averaging the detection signal, so that the positioning tolerance is increased and the influence of random noise components and variations in the local composition and structure of the medium Is averaged and becomes smaller. However, the GMR film still has a low resistance value because copper, which is a good conductor, is usually used for the nonmagnetic layer, and there is a problem of heat generation of the element and a decrease in reliability caused thereby. Moreover, it has the fault that power consumption is also large. Heat generation causes a change in resistance of the magnetic detection element, and the midpoint potential fluctuates, resulting in a decrease in accuracy. Therefore, there has been a demand for a magnetic position rotation detecting element that is small in size and has high resolution, as well as high reliability and high stability.

  In view of the above problems, an object of the present invention is to provide a magnetic position rotation detecting element having sufficient resolution, small size, high reliability and stability, and excellent mass production.

  (1) The present invention relates to a magnetic medium in which a magnetization pattern is recorded at a fixed magnetization pitch, and an artificial lattice magnetoresistive element that moves relative to the magnetic medium and detects the magnetization pattern ( GMR element), the magnetically sensitive portion of the GMR element has a length of at least twice the magnetization pitch in the relative movement direction, and the magnetically sensitive portion periodically changes in the relative movement direction. This is a magnetic position rotation detecting element having the above shape. Here, the magnetization pitch (hereinafter also referred to as λ) refers to the distance between adjacent S poles and N poles. Conventionally, the length of the relative direction of movement of the magnetically sensitive portion of the GMR element was less than the magnetization pitch, but the resistance of the element is reduced by taking the magnetically sensitive portion longer than twice the magnetization pitch. The power consumption can be increased, power consumption can be suppressed, and characteristic variation due to heat generation can be prevented. Furthermore, since there is an effect of spatially averaging the detection signals, it contributes to the improvement of the positioning tolerance and the averaging of influences such as local characteristic variations of the medium. Moreover, the relative position between the magnetic medium and the GMR element is changed even in the configuration in which the magnetically sensitive part has a shape that is periodically changed, so that the magnetically sensitive part has a length of more than twice the magnetization pitch. At this time, the resistance change of the GMR element occurs, and the position can be detected with high resolution through the resistance change.

  (2) Another aspect of the present invention is the magnetic position rotation detecting element according to the above (1), wherein the GMR element has a shape that periodically changes in the relative movement direction of the magnetically sensitive portion. It is characterized by a periodic change in the width of the magnetically sensitive portion. With this configuration, the pattern of the magnetically sensitive portion can be simplified and downsized.

  (3) Still another invention is the magnetic position rotation detecting element according to the above (1) or (2), wherein the shape of the magnetically sensitive portion of the GMR element is the relative movement direction. It changes with the same period as a magnetization pitch, It is characterized by the above-mentioned. By making the period of the shape change of the magnetically sensitive portion in the relative movement direction the same as the period of the magnetization pitch, distortion of the output waveform can be suppressed, and highly accurate position detection can be performed.

  (4) Still another aspect of the present invention is the magnetic position rotation detecting element according to the above (1) or (2), wherein the shape of the magnetosensitive part of the artificial lattice magnetoresistive element is relative. It changes in the moving direction at a period of 1 / n (n is a natural number of 2 or more) of the magnetization pitch. In this configuration, by adjusting the shape change of the magnetoresistive effect element to the higher-order spatial harmonic component, only the harmonic component of the spatial magnetic field corresponding to the magnetization pitch can be extracted as an output. With this configuration, position detection with high accuracy is possible.

  (5) Still another aspect of the present invention is the magnetic position rotation detecting element according to any one of (1) to (4) above, wherein the magnetosensitive portion of the artificial lattice magnetoresistive element is relative to each other. It is characterized in that a plurality are arranged in parallel to the general movement direction. In such a configuration, the magnetic field detection portion is arranged not only in the relative movement direction but also in the direction orthogonal to each other and distributed over a wide area, and due to the effect of spatially averaging the detection signals, It is possible to improve the positioning freedom and to average the influence of variations in local characteristics of the medium. Further, when the change in the shape of the relative movement direction is the same phase, the resistance can be increased by connecting them in series.

  (6) Still another aspect of the present invention is the magnetic position rotation detection element according to the above (5), in which the plurality of parallel magnetic sensing portions are each shaped in a relative movement direction. It is characterized by being arranged with a shift of 1 / m (m is a natural number of 2 or more) of the change pitch. For example, when they are arranged with a shift of λ / 2, the output is in an opposite phase and receives almost the same resistance change such as a temperature change and external noise. Therefore, when this connection point is used as an output terminal, the signal output amplitude is 2 The output voltage does not change against disturbance. This configuration has the effect of canceling the second order (even order) harmonic components. Similarly, when arranged by shifting by λ / 3, it is possible to cancel the third-order spatial harmonics and obtain a sine wave output with fewer harmonic components.

  In the present invention, since the GMR pattern can be densely arranged even in a small area and the length thereof can be increased, the resistance value is high, and current consumption and heat generation are small. In addition, since there are few connection parts inside the pattern, reliability and stability are high, and mass productivity is also excellent. Further, since the output can be averaged over a wide area, there is little influence of local characteristic fluctuation due to a scratch on the medium, and the degree of freedom of attachment is large. Further, since the magnetically sensitive portion of the GMR element of the present invention is long in the relative movement direction, even if the magnetically sensitive portion is mounted inclined in the relative movement direction, the influence of the angle error on the signal is small. The tolerance of azimuth is increased. In addition, it is possible to provide an element for detecting position rotation with small waveform distortion and excellent resolution.

  In the present invention, an optimum GMR element is used as a detection element as a high-resolution magnetic position rotation detection element. Generally, a film in which 10 or more layers of nanometer order Ni—Fe (permalloy) and copper thin films are alternately laminated on a glass substrate is used. The saturation magnetic field of this film is several kA / m, and the rate of change in resistance at that time is about four times that of a permalloy single layer film and about 10%. In the present invention, a pattern is used in which the magnetically sensitive portion of the GMR element is long in the relative movement direction and the shape thereof is periodically changed in this direction. The length of the magnetically sensitive portion is at least twice as long as the magnetization pitch of the magnetization pattern of the magnetic medium in order to have a structure that averages the output and to increase the resistance. It is preferable that it is sufficiently long. Even if the rectangular magnetic sensitive part is simply lengthened, it does not function as a magnetic position rotation detection element, but it is detected by periodically changing the shape of the magnetic sensitive part simultaneously with the expansion of the magnetic sensitive part. One of the features of the present invention is to realize a function as an element. The detection output can be averaged over a wide spatial range by making the length of the magnetosensitive part more than twice the magnetization pitch of the magnetization pattern, so the effect of local characteristic fluctuations is reduced. The allowable range of attachment is also increased. Further, in the conventional method, when one magnetosensitive pattern having a length L, which is long in the track width direction of the magnetization pattern, is attached with an inclination of θ, the error with respect to the phase is L × sin θ / wavelength. When the magnetosensitive pattern is long in the relative movement direction as in the invention, the error is L × (1−cos θ) / wavelength. Since the error θ is usually small, in this case, the signal amplitude decreases with a quadratic function with respect to the angle. Therefore, even when the magnetically sensitive part is attached with an inclination in the relative moving direction, the influence of the angle error on the signal is small, and the allowable range of azimuth becomes high at the time of attachment.

  In the present invention, the shape of the pattern of the magnetically sensitive portion is periodically changed in the relative movement direction. With this configuration, magnetic detection can be performed even when the length of the magnetically sensitive portion is set to be twice or more the magnetization pitch of the magnetization pattern. The change in the shape may be due to a change in thickness in addition to the planar shape of the magnetically sensitive portion, but it is preferable to change the planar shape for easy production. There are two methods for changing the planar shape, such as changing the pattern width of the magnetically sensitive part, and changing the shape and number of holes in the magnetically sensitive part. In order to use the space effectively, for example, in the case of disposing them in parallel, it is desirable to change the pattern width of the magnetically sensitive portion. As a first embodiment for changing the shape of the magnetically sensitive part, a method for changing the width of the pattern of the magnetically sensitive part is shown in FIG. The pattern of FIG. 1 is an example in which the width changes smoothly and periodically with a period λ. FIG. 2 shows a method of providing a hollow as a second embodiment for changing the shape of the magnetically sensitive portion. In the pattern of FIG. 2, hollows are provided, and the hollows are periodically arranged. The hollow shape is not limited to a rectangle, and may be a circle, for example. On the other hand, since the period of the shape change is the same as the magnetization pitch, this magnetically sensitive part operates as a spatial frequency filter, so that only the fundamental wave can be extracted and unnecessary harmonic components are suppressed. An output with small waveform distortion can be obtained. Further, it can be changed with a period of 1 / n of the magnetization pitch (n is a natural number of 2 or more). In this configuration, only the harmonics of the fundamental wave corresponding to the magnetization pitch are extracted. Even with this configuration, position detection with high accuracy is possible.

  The effect of periodically changing the shape of the pattern of the magnetically sensitive portion will be described below, taking as an example the case where the width is changed in the pattern of FIG. 1 at the same period as the magnetization pitch. The magnetic sensitive pattern has a change in width, and is configured such that a portion that produces the magnetic flux collecting effect of the ferromagnetic material and a portion that causes resistance change through the collected magnetic flux alternately and continuously change. FIG. 3 is a schematic diagram showing the flow of magnetic flux when the magnetosensitive part moves relative to the magnetization pattern of the medium. When one wide part with a magnetic sensitive pattern is close to the magnetic pole center of the magnetic medium magnetization pattern (upper figure in Fig. 3), the wide part of the adjacent pattern is closest to the reverse polarity magnetic pole, The magnetic flux passes through. At this time, the magnetic flux is converged at a portion where the pattern is narrowed, resulting in a large resistance change (decrease). On the other hand, when this narrowed part comes close to the magnetic pole (lower figure in FIG. 3), the magnetic flux from the magnetic pole is so narrow that it is difficult to gather and the wide part is far away from the magnetic pole of the medium. It doesn't contribute to the collection, and resistance change hardly occurs. Such a change in the resistance value occurs due to a change in the relative position between the magnetic medium and the GMR element, so that the position information can be detected. In addition, the magnetic sensing pattern of the GMR element collects magnetic fluxes in different directions alternately for each magnetization pitch from the medium in accordance with the relative movement with the medium, and the magnetic flux flows in the narrowed portion of the pattern. produce. That is, the magnetic field received by one magnetosensitive pattern is in the longitudinal direction of the pattern, but the direction of the magnetic field is reversed for each adjacent magnetization pitch. The element resistance is inversely proportional to the cross-sectional area of each section and the element resistance is the sum of them even if the magnetic flux changes in the minute section are the same. The received GMR element receives a spatially sinusoidal magnetic field, and sums up the resistance change over the entire pattern, thereby automatically causing a sinusoidal resistance change and outputting a sinusoidal voltage. From this consideration, in order to bring about a sine wave resistance change, it is desirable that the pattern width also gives a sine wave width change.

  The relationship between the pattern shape of the magnetically sensitive portion and the direction in which the magnetic field is applied will be further described in detail. In a conventional ferromagnetic magnetoresistive effect element using permalloy, a resistance change occurs according to the cosine of the angle formed by the current and the direction of magnetization. Magnetization tends to be oriented in the longitudinal direction due to the shape anisotropy, but in order to move the orientation of the magnetization from the longitudinal direction, it is necessary to apply a magnetic field in the short direction perpendicular to the longitudinal direction. In this case, it is assumed that the whole operation is considered as one magnetic mass, and otherwise, it has been considered to cause a problematic operation such as Barkhausen noise and hysteresis. On the other hand, in the case of GMR, the angle difference in the magnetization direction between layers is a cause of resistance change. At this time, the magnitude of the resistance change does not change greatly depending on the direction of the magnetic field, but more accurately, a slightly larger resistance change can be obtained by applying a magnetic field in the longitudinal direction of the pattern due to shape anisotropy. However, in this case as well, it is not assumed that the direction of magnetization is reversed in the pattern forming a single magnetosensitive element. However, the inventor paid attention to the dependence of the ferromagnetic magnetoresistance effect element (AMR element) and the GMR element shown in FIG. Here, Hk refers to a magnetic field in which the slope portion of the resistance change is linearly approximated and the resistance change on the straight line becomes 0% in the resistance change with respect to the applied magnetic field. It can be said that the smaller the Hk, the higher the sensitivity because the resistance value changes in a low magnetic field. In permalloy, when the pattern width is narrowed, Hk increases, and the sensitivity rapidly decreases. However, in GMR, the sensitivity does not decrease even if the pattern width is 5 μm. This is because the GMR film may be weakly coupled as a ferromagnetic material within one pattern as compared with permalloy. For example, while permalloy operates as a lump of magnetic material (single magnetization) even when separated by 20 μm, GMR operates as a separate magnetic material with weak coupling as a ferromagnetic material when separated by 5 μm or more even within the same pattern. I thought. This means that the direction of the magnetic field can be freely changed spatially and freely within one magnetosensitive pattern without lowering the sensitivity. This is a significant difference from the prior art.

  In the GMR element of the present invention, a plurality of patterns having a length of twice or more the magnetization pitch can be arranged in parallel. It is easy to increase the resistance value by connecting the patterns having the same phase in a periodic shape change in the relative movement direction in a zigzag manner and connecting them in series. In addition, by arranging the phase shift by 1 / m (m is a natural number of 2 or more) of the pitch of the shape change in the relative movement direction, the output can be differentiated. For example, in the case where they are shifted by λ / 2 (180 degrees), the output has an opposite phase, and second-order (even-order) harmonic components can be canceled out. Further, by arranging by shifting by λ / 4, it is possible to obtain an output whose phase is shifted by 90 degrees, and to determine whether the relative moving direction is positive or negative. Note that a plurality of patterns having the same phase connected in series can be arranged with a phase shift of 1 / m (m is a natural number of 2 or more) of the pitch of shape change in the relative movement direction.

Next, an example of detection signal output will be described with reference to FIG.
(1-1) Prepare a plurality of magnetosensitive patterns whose shapes change with the same phase as a reference, connect them in series, and connect one to the power supply Vdd.
(1-2) Further, the same number of the magnetosensitive patterns as the pattern of (1-1) are prepared, which are 180 degrees out of phase with the reference magnetosensitive pattern and change in shape in the same phase, that is, shifted by λ / 2. These are connected in series, one is connected to the common potential and the other is connected in series to the previous pattern (1-1).
(1-3) This connection point, that is, the middle point is connected to one input terminal (for example, positive input A1) of the differential amplifier A.
(2-1) Further, prepare the same number of magnetic sensing patterns that are 180 degrees different in phase from the reference magnetic sensing pattern and change in shape in the same phase as the pattern in (1-1), connect them in series, Connect to power supply Vdd.
(2-2) Furthermore, the same number of magnetosensitive patterns as the pattern of (1-1) are prepared in the same phase as the pattern of (2-1), and the phase is 180 degrees different from the pattern of (2-1). One is connected to a common potential and the other is connected in series with the previous pattern (2-1).
(2-3) This connection point, that is, the middle point is connected to the remaining input terminal (negative input A2) of the differential amplifier A.
The bridge composed of the four magnetoresistive element groups and the differential amplifier A obtain an output of 0 degree.

In order to determine whether the relative moving direction is positive or negative, an output that is 90 degrees different from the above is usually required. Therefore, the 90-degree output is described next.
(3-1) Prepare a plurality of magnetosensitive patterns that differ 90 degrees from the reference, that is, change their shape in the same phase shifted from the reference in the λ / 4 forward direction, connect them in series, and connect one to the power supply Vdd To do.
(3-2) Furthermore, the same number of magnetosensitive patterns that are 180 degrees different in phase from the magnetosensitive pattern of (3-1) and change in shape in the same phase, that is, shifted in the opposite direction from the reference by λ × 3/4 are prepared. Then, they are connected in series, one is connected to the common potential and the other is connected in series to the previous pattern (3-1).
(3-3) This connection point, that is, the middle point is connected to one input terminal (for example, positive input B1) of another differential amplifier B.
(4-1) Furthermore, a magnetic sensitive pattern whose phase is 270 degrees different from that of the reference magnetic sensitive pattern, that is, shifted in the opposite direction from the reference by λ × 3/4 and whose shape changes in the same phase is the pattern of (3-1). Prepare the same number of them, connect them in series, and connect one to the common potential.
(4-2) Furthermore, the same number of magnetic sensitive patterns as the pattern of (3-1) are prepared in the same phase as the pattern of (4-1), and the phase is 180 degrees different from the pattern of (4-1). , One is connected to the power supply Vdd, and the other is connected in series with the pattern (4-1).
(4-3) This connection point, that is, the middle point is connected to the remaining input terminal (negative input B2) of the differential amplifier B.
A 90-degree output is obtained by the bridge composed of the four magnetoresistive element groups and the differential amplifier B.

  A magnetic position rotation detecting element according to the present invention is composed of a GMR element that causes a large change in magnetoresistance and a medium obtained by applying and magnetizing a resin mixed with magnetic powder. It is a linear sensor. An example of the configuration is shown in FIG. Hereinafter, a combination and configuration of the GMR element and the magnetic medium will be specifically described based on the embodiment.

Example 1
For magnetic media that are coated media. Magnetization was performed using a magnetic head at a recording pitch (between S pole and N pole) of 20 μm. A schematic diagram of the laminated structure of the GMR used is shown in FIG. On a silicon substrate insulated by an oxide film, a magnetic material mainly composed of permalloy having a thickness of 1.3 to 1.8 nm and copper having a thickness of 2 to 3 nm were alternately laminated by 14-layer sputtering (FIG. 6). Then, some of the number of layers was saved). FIG. 7 shows how the resistance of the film changes with respect to the applied magnetic field. As a comparison, changes in the ferromagnetic magnetoresistive film (AMR) are also shown. FIG. 8 is a pattern diagram of the present invention of a GMR element for detecting a magnetic signal from this medium. The pattern length is 300 μm, which is 15 times longer than the recording pitch. The width of the pattern is 10 μm at the maximum and about 2 μm at the minimum, and follows a formula of approximately 3 / (1−0.7 × sin (2 × π × x / λ)) μm with respect to the relative movement direction coordinate x. The pattern width was continuously changed. This pattern and a pattern obtained by moving this pattern in the 10 μm pitch direction were combined into a set, and a total of 6 sets were patterned in parallel. FIG. 9 shows the dependence of the output voltage on the gap (interval between the magnetic medium and the detection element). The amplitude hardly changes from the point in contact with the magnetic medium to about 10 μm. Further, FIG. 10 shows an output waveform when it is in contact with which distortion is most likely to occur. Since the medium and the detection element are in contact with each other, friction is irregularly generated and the rotation is not uniform, so that the time axis varies, but a waveform with a small sine wave distortion is obtained. Although the GMR film is sensitive to the magnetic field in the short direction of the pattern, both sides of the half bridge are arranged close to each other. Never appeared in the output. The element resistance was 1048Ω.

(Examples 2 to 4)
A pattern with a change in pattern width from a sinusoidal shape to a simpler step or trapezoidal shape was produced. The patterns used are shown in FIGS. The gap dependence and output at that time are shown in FIG. The trapezoidal pattern had the largest output, but there was no significant difference, and in both cases, a sine wave output was obtained as shown in FIGS. 14 to 16, and the amplitude did not change up to a gap of 10 μm, and the output was reduced to half. The range was about 15 μm. The element resistances were 1069Ω, 985Ω, and 913Ω in the case of Example 2, Example 3, and Example 4, respectively.

  In the present invention, it is easy to shape the waveform, and it can be seen that what is conventionally not usable at a gap of 5 μm or less due to excessive distortion can be used until the magnetic medium and the detection element come into contact with each other. It has been found that the conventional method can use only up to about 10 μm, where the output is halved, but can use up to 15 μm. Therefore, the usable range is expanded from 5 μm to 15 μm. Further, since the GMR having a large resistance change rate is used, the output voltage amplitude is as large as about 100 mV. For this reason, it was also possible to input to the comparator without amplification.

(Comparative Example 1)
A rectangular pattern GMR element having the conventional arrangement shown in FIG. 17 was produced. The width of the magnetically sensitive portion in the relative movement direction is 6 μm, and the pitch is 20 μm. The gap dependency of the output voltage is shown in FIG. With a gap of 10 μm, the output dropped to about half that when the magnetic medium was close. Further, FIG. 18 shows the bridge output in the case where it is arranged close to the magnetic medium. As shown in FIG. 18, in this comparative example, the maximum value of the output amplitude when close to the medium is about 30% larger than that of the embodiment, but the output waveform is excessively distorted and far from the sine wave. It was. Further, the element resistance was 657Ω, which was lower than those of Examples 1 to 4.

(Example 5)
A position rotation detecting element was manufactured for the purpose of obtaining a resolution of 2.5 μm by the same medium magnetization method. In order to realize the resolution, the conventional method required high mounting accuracy. The pattern is shown in FIG. Grounded at GND, a voltage is applied from Vdd, outputs A1 and A2 are connected to differential amplifier A, and outputs B1 and B2 are connected to differential amplifier B. In Example 1, the phase difference of each pattern was 0 degrees and 180 degrees, but in this experiment, a pattern having a phase difference of 90 degrees was included so that the moving direction could be understood. The dimension of patterning of the GMR film is 300 μm in length and 300 μm in width. The element resistance when the two bridge circuits were viewed from the power source was about 1.2 kilohms because the pattern was dense even with such a small size. This value is a current consumption of 4 mA even when the power supply voltage is 5 V, only a power loss of 20 mW, and is not a problem of heat generation in view of the element dimensions. The final resolution of 2.5 μm could be easily obtained by multiplying using the circuit shown in FIG.

It is a pattern figure of the GMR element magnetosensitive part of 1st embodiment of this invention. It is a pattern figure of the GMR element magnetosensitive part of 2nd embodiment of this invention. It is a schematic diagram for demonstrating the flow of the magnetic flux with respect to the GMR pattern of this invention. It is a figure which shows the width (w) dependence of Hk of a GMR element. 1 is a schematic external view showing an example of a magnetic position rotation detector (encoder). It is the schematic which shows the film | membrane structure of GMR. It is a figure which shows the characteristic of the resistance change rate of a GMR element. FIG. 3 is a pattern diagram of a GMR element magnetic sensing portion of Example 1. It is a figure which shows the gap dependence of an output. FIG. 6 is a diagram illustrating an example of an output waveform according to the first embodiment. 6 is a pattern diagram of a GMR element magnetic sensing portion of Example 2. FIG. FIG. 10 is a pattern diagram of a GMR element magnetic sensing portion of Example 3. FIG. 6 is a pattern diagram of a GMR element magnetic sensing part of Example 4. It is a figure which shows the example of the output waveform of Example 2. FIG. It is a figure which shows the example of the output waveform of Example 3. FIG. It is a figure which shows the example of the output waveform of Example 4. FIG. It is a figure which shows the element pattern of the comparative example which is a prior art example. It is a figure which shows the example of the output waveform of the comparative example which is a prior art example. It is a figure which shows the pattern of the GMR element of this invention Example 5. FIG. It is a figure which shows the circuit of Example 5 of this invention.

Explanation of symbols

1: Magnetic medium, 2: Magnetic position rotation detector, 3: Gap, 4: Substrate, 5: Underlayer 6: Nonmagnetic metal layer, 7: Ferromagnetic layer, 8: Surface protective film

Claims (6)

  A magnetic medium on which a magnetization pattern is recorded at a fixed magnetization pitch; and an artificial lattice magnetoresistive element that moves relative to the magnetic medium and detects the magnetization pattern; and A magnetic position in which the magnetically sensitive portion of the resistive element has a length that is at least twice the magnetization pitch in the relative movement direction, and the magnetically sensitive portion periodically changes in the relative movement direction. Rotation detection element.   2. The magnetic position rotation detection according to claim 1, wherein the shape of the artificial lattice magnetoresistive element periodically changed in the relative movement direction of the magnetically sensitive portion is a periodic change in the width of the magnetically sensitive portion. element.   The magnetic position rotation detecting element according to claim 1 or 2, wherein the shape of the magnetically sensitive portion of the artificial lattice magnetoresistive element changes in the relative movement direction at the same period as the magnetization pitch.   3. The magnetic type according to claim 1, wherein the shape of the magnetically sensitive portion of the artificial lattice magnetoresistive effect element changes in a relative movement direction at a period of 1 / n of the magnetization pitch (n is a natural number of 2 or more). Position rotation detection element.   The magnetic position rotation detection element according to any one of claims 1 to 4, wherein a plurality of magnetically sensitive portions of the artificial lattice magnetoresistive effect element are arranged in parallel to the relative movement direction.   6. The magnetic position according to claim 5, wherein a plurality of the magnetically-sensitive portions arranged in parallel are arranged with a shift of 1 / m (m is a natural number of 2 or more) of the pitch of shape change in the relative movement direction. Rotation detection element.

Images