JPH0777531A - Magnetic position/rotation detecting element - Google Patents

Abstract

PURPOSE:To allow a detecting element to be miniaturized while increasing the output by arranging the signal field from an object to be detected in parallel with the longitudinal direction of a magnetosensitive pattern. CONSTITUTION:A signal field 6 from an object to be detected, a pattern 7 at a magnetosensitive part, a pectinated route 8, etc., are provided. The width W of pattern at the magnetosensitive part is determined according to a formula; Hk=Ha+4piIs.T/W, where Hk: saturation field of element, Ha: essential saturation field of magnetic film, Is: saturation magnetization, T/W: reverse field constant. The pattern width W contributes significantly to HK. When the pattern width W is decreased, the HK decreases and the magnetic sensitivity increase. Consequently, when the sensitivity is increased by decreasing the HK, the magnetosensitive pattern width decreases and the resistance of element increases and thereby, the pattern describing range is limited for the same design resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic position / detection / rotation detecting element using an artificial lattice film having a magnetoresistive effect.

[0002]

2. Description of the Related Art In a general ferromagnetic metal, the electric resistance is maximum when the magnetization direction and the current direction are parallel to each other and minimum when both are perpendicular to each other. As a quantity representing the magnitude of the anisotropic magnetoresistive effect, the difference between the maximum and minimum Δρ = ρ (parallel) −
Ratio Δρ between ρ (orthogonal) and the resistance value ρ ₀ when the applied magnetic field is 0
/ Ρ ₀ is used. Ni-Co-based and Ni-Fe-based alloys are known as materials having a large Δρ / ρ ₀ at room temperature. These Δρ / ρ ₀ are about 3 to 5%.

However, the ferromagnetic magnetoresistive element does not show a change in the resistance value with respect to magnetism exceeding the saturation magnetic field amount, and the absolute amount of the change in the resistance value is as small as 5% at maximum. It is smaller than the element, and it is necessary to use the sensor surface close to the object to be detected up to a distance (air gap) approximately the same as the detection pitch, which is a major obstacle to use.

On the other hand, the ferromagnetic magnetoresistive element has a film thickness of about 500 made of nickel alloy on a glass or ceramic substrate.
The ferromagnetic magnetoresistive thin film of Å is patterned and connected to the lead wire via the electrode. The protective film of the ferromagnetic magnetoresistive thin film is formed by coating SiN and epoxy resin or polyimide resin, for example. Figure 1
2 is a structural sectional view of a conventional ferromagnetic magnetoresistive element.
8 is a ferromagnetic magnetoresistive thin film, 29 is a substrate, 30 is a protective film,
Reference numeral 31 is an electrode, and 32 is a lead wire.

FIG. 13 shows an example of a conventional detection method of a ferromagnetic magnetoresistive element. When the distance from the center of the N pole to the center of the N pole of the magnetized pattern of the object to be detected is λ, the pattern elements are arranged at λ / 4 intervals. 33A and 33B are magnetic sensitive patterns of a nickel alloy ferromagnetic magnetoresistive thin film, and 34 is a constant voltage applying electrode (hereinafter referred to as VCC).
, 35 is a ground electrode (hereinafter referred to as GND),
Reference numeral 36 denotes an output detection electrode (hereinafter referred to as FG).
FIG. 14 is a diagram showing the positional relationship between the magnetically sensitive pattern and the detected body. Reference numeral 10 denotes a magnetized pattern of the detected object, and 6 denotes a signal magnetic field of the detected object. According to this, the pattern 33A is arranged at a distance of λ / 4 from the pattern 33B, and the magnetic flux in the parallel direction passes through the pattern 33A due to the signal magnetic field from the object to be detected, and the resistance value is reduced by about 5%. To do. on the other hand,
Since the magnetic flux does not pass through the pattern 33B, the resistance value does not change. When the potential difference between FG and GND is detected as a signal, the potential difference that becomes this signal also changes according to the change in the relative positional relationship between the detected object and the detection element.

FIG. 15 shows a detected output waveform when the device is operated by the configuration of FIG. As a result, the same number of pulses as the magnetized number of the object to be detected is detected. FIG. 16 shows an air gap from the element surface to the surface of the object to be detected when a magnetized rotor having a magnetizing pitch width, that is, λ / 2 of 150 μm is used for the object to be detected constructed as shown in FIG. It is a figure showing the relation of detection output (voltage amplitude). As is clear from this, the output voltage tends to have a maximum value when the air gap width is almost the same value as the magnetizing pitch.

On the other hand, in recent years, a large magnetoresistive effect is obtained in an artificial lattice film in which ferromagnetic layers and non-ferromagnetic layers are alternately stacked and coupled so that the magnetizations of adjacent ferromagnetic layers are antiparallel. It has been discovered that it will appear, and is attracting attention. The artificial lattice film is composed of a ferromagnetic layer such as NiFeCo and a non-ferromagnetic metal such as Cu as shown in JP-A-4-329683 and the like, and the magnetic layer is antiferromagnetically coupled by RKKY magnetic coupling. When it shows a large magnetoresistive effect.

The difference between the artificial lattice film and the conventional ferromagnetic magnetoresistive film lies in the magnitude of the magnetoresistive change rate and the direction of magnetic anisotropy and resistance value change. The rate of change in magnetoresistance is 5% at maximum for ferromagnetic magnetoresistive film, but at least 1 for artificial lattice film.
It is 5% or more. With respect to the direction in which the magnetic anisotropy and the resistance value change, the resistance value decreases in the ferromagnetic magnetoresistive film when the magnetized direction and the current direction are perpendicular, whereas in the artificial lattice film, There is no anisotropy, and the resistance value isotropically decreases when magnetized. Therefore, when calculating the saturation magnetic field of the magnetoresistive element, the necessary formula is Hk = Ha + 4πIs · T / W (1) Hk: Saturation magnetic field of element Ha: Original saturation magnetic field Is of magnetic film: Saturation magnetization T / W: In the case of a ferromagnetic film, the magnetic field is perpendicular to the current direction, that is, the longitudinal direction of the pattern, which can be calculated as T: film thickness, W: pattern width. In the case of an artificial lattice film, The magnetic field may be parallel to the current direction, that is, the pattern longitudinal direction, and the replacement in the calculation at this time is represented by T: pattern width and W: pattern length.

For this reason, the shape of the magnetic sensitive pattern must be different from that of the ferromagnetic magnetoresistive element, but at present, a magnetic position / rotation detection method (a method for magnetizing the object to be detected and The positional relationship) and patterning method have not been established.

[0010]

The magnetic position / rotation detecting element using the conventional ferromagnetic magnetoresistive element is a sensor using a thin film, but is used very close to the object to be detected which is a moving body. There is a need. For this reason, the thin protective film is often damaged by the contact with the detection object which is a moving body, and the reliability of the element is often impaired.

When applied to a driving voltage of 5V of a commonly used precision motor, the processing circuit does not operate unless the threshold voltage is 30 mV or higher. Output 30 of FIG.
Focusing on mV, it can be seen that the air gap that enables the ferromagnetic magnetoresistive element to detect rotation or position is about 180 μm or less.

Further, the improvement of the magnetic sensitivity by the patterning required for the magnetic sensor is generally achieved by the saturation magnetic field strength (Hk).
By reducing. FIG. 11 shows the relationship between the magnetoresistive change rate of the ferromagnetic magnetoresistive film and the magnetic field strength, where 48 is the magnetoresistive characteristic of the low-sensitivity element, and 49 is the magnetoresistive characteristic of the high-sensitivity element. The horizontal axis represents the magnetic field strength, and the vertical axis represents the magnetoresistance change rate. From this figure, it is understood that the smaller the saturation magnetic field strength (Hk), the smaller the saturation magnetic field strength (Hk) of the magnetoresistive characteristic, the more the resistance value changes in response to the low magnetic field, and the magnetic field sensitivity is improved.

In the case of a ferromagnetic magnetoresistive element, in order to improve the magnetic field sensitivity, it is necessary to increase the pattern width or reduce the film thickness, as is clear from the equation (1). As a result, the pattern width is increased. Therefore, a larger pattern drawing area is required to obtain a predetermined resistance value, and the physical property value of the magnetoresistive film is lowered by reducing the film thickness, resulting in poor sensor characteristics and reliability. It drops.

As described above, since the conventional ferromagnetic magnetoresistive element has a low detection output voltage, there are many restrictions on mounting and element shape, and it has been difficult to introduce it at low cost.

In view of the above problems, the present invention provides a magnetic rotation and position detecting element which has a high output and can be miniaturized.

[0016]

In order to solve the above-mentioned problems, the present invention provides a magnetic sensitive pattern element shape of an element using an artificial lattice film in which ferromagnetic layers and non-ferromagnetic layers are alternately laminated. The signal magnetic field from the detector and the longitudinal direction of the magnetic sensitive pattern are arranged in parallel.

[0017]

With the above structure, the sensitivity pattern is increased as seen in the ferromagnetic film, that is, the resistance pattern region is expanded by widening the magnetosensitive pattern width or increasing the film thickness of the magnetosensitive film. Can be prevented. Therefore, the sensitivity is improved, and the magnetic field can be sensed in a small pattern region, so that the device can respond to a minute magnetization signal.

[0018]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below.
FIG. 1 is a sectional view of an element according to an embodiment of the present invention. 1 is [Co
Fe / Cu] ^N or [Ni.Fe.Co/Cu] ^N or [Ni.Fe.Co/Cu/Co/Cu] ^N (N is the number of laminated layers) based artificial lattice film, 2 is a substrate, 3 is a protective film 4 is an electrode,
5 is a lead wire. FIG. 2 is a patterning shape of the artificial lattice film of the embodiment of the present invention, 6 is a signal magnetic field from the object to be detected, 7 is a pattern of a magnetically sensitive portion, 8 is a pattern of routing, and 9 is a magnetizing pitch of the object to be detected. 1/2 of λ / 4
Shows the distance. Further, here, the magnetic sensitive pattern is drawn in a direction parallel to the signal magnetic field. Further, the pattern width of the magnetically sensitive portion of the pattern greatly contributes to the value of Hk as shown in the above equation (1). That is, if the pattern width is narrowed, Hk
Is reduced, and the magnetic sensitivity is improved. For this reason, if the sensitivity is improved (Hk is decreased), the width of the magneto-sensitive pattern is narrowed, and the resistance value of the element is increased. When the resistors are designed with the same resistance value, the pattern drawing range is reduced.

FIG. 3 shows an output detection system according to an embodiment of the present invention using a detection element having the pattern shape shown in FIG. 1
Reference numeral 0 is an object to be detected, 11A and 11B are magnetic sensing patterns of the artificial lattice film, 12 is VCC, 13 is GND, and 14 is FG. According to this, the pattern A is arranged so as to be separated from the pattern B by λ / 4, and the magnetic flux in the parallel direction passes through the pattern 11A due to the signal magnetic field from the detected object, and the resistance value is reduced by about 15%. To do. On the other hand, since the magnetic flux does not pass through the pattern 11B, the resistance value does not change. Similar to the conventional example, the potential difference between FG and GND is detected as a signal.

FIG. 4 shows detected output waveforms when the device is operated with the configuration of FIG. As a result, the same number of pulses as the number of detection output pulses of the conventional ferromagnetic magnetoresistive element in the λ / 4 arrangement can be obtained. FIG. 5 is a diagram showing the relationship between the air gap from the element surface to the surface of the object to be detected and the detection output at an applied voltage of 5 V in the configuration of FIG. As is clear from this, as compared with the conventional example, the position and rotation detection element using the artificial lattice film can detect an output four times or more.

(Second Embodiment) The second embodiment of the present invention will be described below. FIG. 1 is a sectional view of an element of the second embodiment of the present invention, which is the same as the first embodiment.

FIG. 6 shows the patterning shape of the artificial lattice film of the second embodiment of the present invention. In FIG. 6, 15A, 1
5B is a patterning shape of the artificial lattice film of the embodiment of the present invention. The distance between the patterns 15A and 15B corresponds to λ / 2, which is the magnetization pitch of the object to be detected. In this case, unlike the pattern shape of λ / 4 as in the first embodiment, the magnetic sensitive pattern may be arranged perpendicularly to the moving direction of the detected object as in the case of the ferromagnetic magnetoresistive element. . However, Hk
The calculation formula of is according to (1), T corresponds to the pattern width, and W corresponds to the pattern length. FIG. 7 shows an output detection method according to an embodiment of the present invention using a detection element having the pattern shape shown in FIG. Reference numeral 10 is an object to be detected, 15A and 15B are magnetic sensing patterns of the artificial lattice film, 19 is VCC, 20 is GND, and 21 is F.
G, 22a and 22b are magnetic fields applied from the bias magnet. According to this, the pattern 15A is arranged at a distance of λ / 2 from the pattern 15B, and the bias magnetic field near the pattern 15A moves to the position a1 due to the signal magnetic field a from the detection object. As a result, the resistance value of the pattern 15A is reduced by about 15%. On the other hand, the bias magnetic field near the pattern 15B is b due to the signal magnetic field b from the detected object.
Move to position 1. Since this magnetic field is perpendicular to the pattern 15B, the resistance value of the pattern B does not change. As described above, the potential difference between the patterns 15A and 15B changes. This change is detected as a signal from the FG 21. In the case of this detection method, the bias magnetic field is provided on the magnetic sensitive pattern, but this eliminates the hysteresis of the artificial lattice film. For this reason, a material having a large hysteresis can be used, and the range of material selection is expanded.

FIG. 8 shows a detection output waveform when the device is operated with the configuration of FIG. FIG. 9 shows the air gap from the element surface to the surface of the object to be detected and the applied voltage of 5 V in the structure of FIG.
It is a figure showing the relation of the detection output at the time. As is clear from this, compared with the conventional example, the position using the artificial lattice film,
The rotation detecting element can detect an output four times or more.

FIG. 10 shows the effect of the leakage magnetic field of the drive magnet of the motor on the Fg output waveform when the motor is incorporated in the capstan motor. The horizontal axis is the distance from the element surface to the object to be detected, and the vertical axis is the AM modulation rate of the output voltage (percentage of (maximum output-minimum output) / minimum output when the rotor of the motor makes one rotation), which is a small value. Is better). According to this, it can be seen that the embodiment of the present invention is affected only by 1/5 or less as compared with the conventional example.

[0025]

As described above, according to the present invention, the following effects can be obtained. 1. Since the detection output can be improved about four times or more, it is less likely to be affected by noise on the output waveform. In addition, since the distance (air gap) between the object to be detected and the element surface can be increased, the element can be easily mounted and the mounting cost can be reduced.
Furthermore, the probability that the magnetic sensitive pattern will be damaged due to the contact between the object to be detected and the element surface is reduced. 2. As described above, when the patterning is performed in the direction parallel to the magnetic field from the object to be detected, the pattern width is reduced when the sensitivity is increased, and the resistance value is increased. Therefore, the pattern drawing portion can be reduced. 3. The AM modulation rate of the Fg output observed when mounted on a capstan motor or the like becomes small.

From the above, high output and low mounting cost,
A magnetoresistive element that can be downsized can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment of the present invention.

FIG. 2 is a pattern diagram of the first embodiment of the present invention.

FIG. 3 is a diagram of an output detection method according to the first embodiment of the present invention.

FIG. 4 is a detection output waveform diagram of the first embodiment of the present invention.

FIG. 5 is a diagram showing the relationship between the air gap and the detection output according to the first embodiment of this invention.

FIG. 6 is a pattern diagram of a second embodiment of the present invention.

FIG. 7 is an output detection system diagram of the second embodiment of the present invention.

FIG. 8 is a detection output waveform diagram of the second embodiment of the present invention.

FIG. 9 is a relationship diagram of the air gap and the detection output according to the second embodiment of the present invention.

FIG. 10 is an air gap and AM of the second embodiment of the present invention.
Modulation rate relationship diagram

FIG. 11 is a diagram showing the relationship between the magnetoresistance change rate and the magnetic field strength of the ferromagnetic magnetoresistive film.

FIG. 12 is a sectional view of a conventional example.

FIG. 13 is a pattern diagram of a conventional example.

FIG. 14 is an output detection method diagram of a conventional example.

FIG. 15 is a detection output waveform diagram of a conventional example.

FIG. 16 is a relational diagram of air gap and detection output of a conventional example.

[Explanation of symbols]

 1 Artificial lattice film 6 Signal magnetic field 7 Magnetic field pattern

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuo Satomi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. In a magneto-sensitive pattern element shape of an element using an artificial lattice film in which ferromagnetic layers and non-ferromagnetic layers are alternately laminated, the signal magnetic field from the object to be detected is parallel to the longitudinal direction of the magneto-sensitive pattern. A magnetic position / rotation detecting element, which is characterized in that 2. A magnetoresistive element using an artificial lattice film in which a ferromagnetic layer and a non-ferromagnetic layer are alternately laminated as a magnetic sensitive material, wherein hysteresis of the magnetic sensitive material is removed by a bias magnetic field. Magnetic position / rotation detecting element.