JPH0914990A - Magneto-resistance sensor - Google Patents

Abstract

PURPOSE: To improve the detecting accuracy and AM variation of a magneto- resistance sensor through the waveform of an MR output regardless of the gap length between a magneto-resistance element and a magnet means. CONSTITUTION: A magneto-resistance element 10 is obtained by arranging magnetism sensitive patterns 111A and 211B composed of a plurality of basic magnetism patterns in which the beltlike pattern of the element 10 which is elongated in a direction nearly perpendicular to the arranging direction of the N- and S-poles of a magnet means and has a magnetism sensitive pattern width which is 0.3-1 time as wide as the pole width in the arranging direction of the N- and S-poles at an interval which is (m+1/2) times as long as the pole width in the arranging direction of the magnetic means and connecting the patterns 111A and 211B in series. Then, a DC voltage is applied across both ends of the patterns 111A and 211B and, at the same time, an output is obtained from the connecting point which works as an output terminal 8.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. Field of Industrial Application Conventional Technology (FIGS. 12 and 13) Problems to be Solved by the Invention (FIGS. 12 and 13) Means for Solving the Problems Action Example (1) First Example (FIGS. 1 to 1) 8) (2) Second embodiment (FIGS. 4, 5, and 8 to 10) (3) Other embodiment (FIG. 11)

[0002]

FIELD OF THE INVENTION The present invention relates to a magnetoresistive sensor,
For example, it can be applied to a device that detects the rotation frequency of a rotating drum or the like using a magnetoresistive element (hereinafter referred to as MR element).

[0003]

2. Description of the Related Art Conventionally, for example, an MR sensor has been used as a frequency generator for detecting the rotation frequency of a rotating drum or the like. In the MR sensor, MR magnets, which are magnets having N and S poles magnetized at equal intervals on a rotating drum, are arranged face-to-face with respect to the MR element, and changes in the magnetic field caused by the rotation of the rotating drum are detected by the MR sensor. The element detects the MR output and outputs the resulting MR output as a frequency signal.

[0004]

By the way, the gear gap between the MR element and the MR magnet is shorter than the predetermined gear tap length due to the problem of the precision of molding the parts when assembling the MR sensor or the temperature change during the operation. Figure 12
As shown in (A), M detected from the electrodes of the MR element
The output waveform near the center of the R output becomes curved. M
As shown in FIG. 12B, the R sensor generates a pulse at the intersection of the MR output and the voltage value of ½ of the power supply voltage V _cc , and uses this as a position signal. The curvature near the center causes a problem that the accuracy of the pulse generation position varies.

Particularly when used as a three-phase MR sensor,
As shown in FIG. 13, interpolation is performed by assuming that the cross points (◯ to ◯) of the three-phase MR outputs A, B, and C are straight lines. Therefore, the curve of the output waveform near the center of the MR outputs A, B, and C has a problem that the detection accuracy is significantly deteriorated.

Further, depending on the combination of the MR element and the MR magnet, if the gear gap between the MR element and the MR magnet is wider than the predetermined gear length, A
There was a problem that the change in M was affected.

The present invention has been made in consideration of the above points, and a magnetoresistive sensor capable of improving the detection accuracy and the AM fluctuation due to the output waveform of the MR output regardless of the gap length between the MR element and the MR magnet. It is a proposal.

[0008]

In order to solve the above problems, in the present invention, in a magnetoresistive sensor, the magnetic pole is extended in a direction substantially orthogonal to the direction in which the N pole and the S pole of the magnet means are arranged, and the N pole is extended. And the pole width in the direction of the S poles is 0.3 to
The first and second magnetic sensitive patterns, which are a plurality of basic magnetic sensitive patterns in which the folded strip-shaped patterns of the magnetoresistive element having the magnetic sensitive pattern width of 1 times, are formed in the magnetic pole width ( A magnetoresistive element is provided which is arranged in series at an interval of m + 1/2) times and is connected in series to apply a DC voltage to both ends of the first and second magnetically sensitive patterns and to obtain an output using the connection point as an output terminal.

[0009]

[Operation] The magnetoresistive element used in the magnetoresistive sensor is
The magnet means extends in a direction substantially orthogonal to the arrangement direction of the N and S poles, and has a magnetic pole width in the arrangement direction of the N and S poles.
The first and second magnetic sensitive patterns, which are a plurality of basic magnetic sensitive patterns in which the folded strip-shaped patterns of the magnetoresistive element having a magnetic sensitive pattern width of 0.3 to 1 times, are formed in the magnetic pole width in the arrangement direction of the magnet means. (M + 1/2) times of the above, they are connected in series and connected in series, a DC voltage is applied to both ends of the first and second magnetically sensitive patterns, and an output is obtained by using the connection point as a magnetoresistive element. Even if the gear gap between the magnet means and the magnet means is narrowed, the detection accuracy by the output waveform of the MR output can be improved, and the AM fluctuation when the gear gap between the magnetoresistive element and the magnet means is widened can be improved.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

(1) First Embodiment In FIG. 1, reference numeral 1 denotes an MR sensor as a whole, and a magnetoresistive element for magnetic detection is provided on an MR magnet 3 magnetized on a side surface of a cylindrical rotating magnetic drum 2. (Hereafter, MR
The elements 4) are arranged so as to face each other. M
The R magnet 3 has N poles and S poles having a magnetic pole width λ alternately magnetized at equal intervals. As shown in FIG. 2, the MR element 4 includes a first magnetic sensitive pattern group 5A composed of two rectangular strip-shaped basic magnetic sensitive patterns 4A and 4B and a second rectangular magnetic strip-shaped basic magnetic sensitive pattern 4C and 4D. Magnetism pattern group 5
B and B are connected in series to form a double pattern. The rectangular portions of the basic magnetic sensitive patterns 4A, 4B, 4C and 4D are bent so that the patterns are parallel to each other, and the distance between the center lines is 1 of the magnetic pole width λ of the MR magnet 3.
It is set to the width of / 2.

A ground terminal 6 and a power supply voltage V _cc terminal 7 are formed at both ends of the MR element 4, and an output terminal 8 is formed at the midpoint between the ground terminal 6 and the power supply voltage V _cc terminal 7. In the MR sensor 1, as shown in FIG. 3, from the state where the direction of the MR element 4 shown by the arrow b is orthogonal to the direction in which the magnetic poles of the N pole and the S pole of the MR magnet 3 shown by the arrow a are aligned. It is tilted at a predetermined angle and is arranged with a predetermined gear length g. The MR sensor 1 uses this MR
Apply the power supply voltage V _cc to the element 4 and set the MR magnet 3 to M
The MR element 4 is moved relative to the R element 4, and the change in the magnetic field caused by the relative movement of the MR magnet 3 is detected by the MR element 4 and output from the output terminal 8 as the MR output V _MR .

The basic magnetic sensitive pattern width d of the MR element 4 is, as shown in FIGS. 2 and 3, basic magnetic sensitive patterns 4A to 4D.
The distance between the centers of the rectangular pattern widths of
[Μm]. In this embodiment, the magnetic pole width λ = 2
Since it is 00 [μm], the distance between the center lines of the basic magnetically sensitive patterns 4B and 4C is set to 100 [μm], which is half the magnetic pole width λ.

When the angle formed by the extension direction b of the MR element 4 and the direction a in which the magnetic poles of the MR magnet 3 are arranged is changed from the orthogonal state, the inclination angle is changed from the orthogonal state of the directions a and b. The basic magnetic sensitive pattern width d changes in accordance with. That is, the basic magnetic sensitive pattern width d is the width of the basic magnetic sensitive patterns 4A to 4D in the direction parallel to the direction a in which the magnetic poles of the MR magnet 3 are arranged. In this way, the basic magnetic sensitive pattern width d is changed, and as a result, the MR output can be changed by changing the ratio d / λ of the basic magnetic sensitive pattern width d and the magnetic pole width λ.

In the above structure, as shown in FIG. 4A, when the arrangement direction a of the MR magnet 3 and the direction b of the MR element 4 are orthogonal to each other, the MR output V _MR is the central portion of the output waveform. Is observed to be curved. The curvature is observed when the gear length g of the MR element 4 and the MR magnet 3 is
Is 25 [μm] to 100 [μm], and the ratio of the magnetic sensitive pattern width d to the magnetic pole width λ is d / λ = 0.125.

Next, the MR element 4 is aligned in the MR direction b.
The basic magnetic sensitive pattern width d is widened by inclining the magnet 3 from a state orthogonal to the magnetic pole arrangement direction a. At this time, the relationship between d / λ and MR output V _MR is d / λ = 0.191
(FIG. 4 (B)), d / λ = 0.256 (FIG. 4 (C)), d /
It becomes λ = 0.322 (FIG. 4 (D)), and it is observed that the curvature of the output waveform in the central portion of the MR output V _MR decreases as the d / λ increases.

That is, when the basic magnetic sensitive pattern width d is not tilted and d / λ = 0.125, the gear step length g25
MR output V _MR observed between [μm] and 100 [μm]
The curvature of the output waveform at the center of the is almost absent when the MR element 4 is tilted d / λ = 0.256, and further d / λ
= 0.322, it can be confirmed that no curvature is seen even at the gear length g = 25 [μm]. Further, it can be confirmed that the curvature does not appear even if d / λ is further increased (FIGS. 5 and 6). Therefore, if the basic magnetic sensitive pattern width d is set to 0.3 λ or more, the MR output V _MR will not be bent even when the gear length g is narrowed, and the MR element 4 with high accuracy can be realized. .

Next, when the MR element 4 is further tilted to increase the basic magnetic sensitive pattern width d and increase the value of d / λ, as shown in FIG. 7, as d / λ increases. M
It is observed that the R output V _MR becomes smaller. Where d / λ
= 1, the MR output V _MR becomes substantially zero, so there is no curvature in the output waveform near the center, and the MR output V _MR detectable range of d / λ is 0.3 ≦ d / λ <1. It turns out that it exists in. Here, the larger the MR output V _MR, the more S / N
The optimum value of d / λ is about 0.3 because it is advantageous in terms of ratio.
It can be.

Here, the MR sensor 1 with d / λ = 0.3
FIG. 8 shows a characteristic curve representing the relationship between the MR magnet 3 and the MR sensor 1 in terms of the gap length g, MR output and AM fluctuation. From this figure, when the gear length g becomes wider, the AM fluctuation of the tilted single pattern MR element is about 90%.
It can be confirmed that the AM fluctuation of the inclined double pattern MR element 4 is kept almost constant regardless of the size of the gear length g, in contrast to the change from about 50% to about 50%.

According to the above construction, the basic magneto-sensitive pattern width d is widened by tilting the double-pattern MR element 4 facing the MR magnet 3, and the basic magneto-sensitive pattern width d and the magnetic pole width λ. By setting the ratio d / λ of about 0.3 to about 0.3, even if the gear length g is narrow, the curvature of the output waveform near the center of the MR output V _MR can be reduced and the accuracy can be improved. It is possible to realize an MR sensor having a small size.

(2) Second Embodiment FIG. 9 in which parts corresponding to those in FIGS. 2 and 3 are designated by the same reference numerals shows the structure of the MR element 10 of the second embodiment. MR element 10
Is formed by series-connecting a first magnetic sensitive pattern group 11A and a second magnetic sensitive pattern group 11B each of which has six basic magnetic sensitive patterns. As shown in FIG. 10, the basic magnetic sensitive pattern of the MR element 10 has a rectangular portion inclined in a predetermined direction by a predetermined angle. Incidentally, the spread (d) of the basic magnetic sensitive pattern at this time is set to a width 0.3 times the magnetic pole width λ of the MR magnet (not shown).

[0022] Each of the two ends _the power supply voltage V _cc terminal 7 of the MR element 10, the ground terminal 6 are formed, the power supply voltage V _cc
An output terminal 8 is formed at the midpoint between the terminal 7 and the ground terminal 6. Each basic magnetic sensitive pattern of the first magnetic sensitive pattern group 11A has a magnetic pole width of 2 from an arbitrary reference point P on the ground terminal 6 side.
Position, 4 times, 6 times (even times) position and 1 time of magnetic pole width λ,
They are arranged at positions of 3 times and 7 times (odd times). Similarly, each basic magnetic sensitive pattern of the second magnetic sensitive pattern group 11B is
2 times the magnetic pole width λ from an arbitrary reference point Q on the output terminal 8 side, 4
Position, 6 times (even number) position, 1 time, 3 times the magnetic pole width λ,
It is arranged at a position of 5 times (odd times). The width between the first magnetic sensitive pattern group 11A and the second magnetic sensitive pattern group 11B is set to (m + 1/2) times the magnetic pole width λ.

In the above structure, in the pattern of the MR sensor, the length direction of the pattern is the easy magnetization direction. Therefore, in the initial stage, the direction of arrow c or 180 shown in FIG.
[°] Facing in the opposite direction. For example, the arrow c is the magnetization direction. Since the magnetic field generated by the MR magnet is in the direction of the XZ plane (the Z axis is the direction perpendicular to the paper surface),
When the magnetic field −X and the magnetic field X are applied as shown in 0,
The angles θ _−X and θ _X with the X axis differ by the amount by which the MR pattern is tilted. Since the MR sensor can obtain a signal for one cycle by moving one magnetic pole, the output level changes every other cycle.

In the MR sensor, the MR element 10 is tilted by a predetermined angle with respect to the direction in which the magnetic poles of the N and S poles of the MR magnet are arranged, and the MR element 10 is arranged so as to hold a predetermined gear length g. The MR sensor has a power source voltage V applied to the MR element 10.
_cc is applied to move the MR magnet relative to the MR element 10, and the change in the magnetic field caused by the relative movement of the MR magnet is detected by the MR element 10. Output as output V _MR .

At this time, the spread of the basic magnetic sensitive pattern (d)
Is 0.3 times the magnetic pole width λ, no bending is seen in the output waveform at the center of the MR output V _MR (FIGS. 4 and 5).
Therefore, even if the gear length g becomes narrow, the MR output V
It is understood that the MR element 10 can be realized with high accuracy without the _MR bending.

The MR of the MR sensor with d / λ = 0.3
Gear length g between MR and MR sensor and MR output,
From FIG. 8 showing the relationship of AM fluctuation, when the gear length g is widened, the AM of the tilted double pattern MR element is shown.
It can be confirmed that the fluctuation is kept almost constant regardless of the size of the gear length g. MR element 1 of the second embodiment
Since 0 is composed of the first magnetic sensitive pattern group 11A and the second magnetic sensitive pattern 11B, the AM fluctuation is held constant in substantially the same manner as the data of the double pattern MR element shown in FIG.

According to the above construction, the pattern width d is set to MR.
By pattern-connecting the first magnetic sensitive pattern group 11A and the second magnetic sensitive pattern group 11B, which are composed of a plurality of basic magnetic sensitive patterns inclined in a certain direction so as to be 0.3 times the magnetic pole width λ of the magnet. Even when the gear length g is narrow, it is possible to reduce the curvature of the output waveform near the center of the MR output V _MR with high accuracy, and even when the gear length g is wide, it is possible to realize an MR sensor with small AM fluctuations.

(3) Other Embodiments In the above first embodiment, the MR element 4 is tilted with respect to the magnetic pole alignment direction a of the MR magnet 3 in order to widen the magnetic sensitive pattern width d. However, the present invention is not limited to this, and for example, as shown in FIGS. 11A and 11B, the magneto-sensitive patterns 15A and 15B or 16A and 16B of the MR elements 15 and 16 facing the MR magnet are provided. The number of bent rectangles may be increased along the direction a in which the magnetic poles of the MR magnet are arranged to increase the area of the magneto-sensitive pattern of the MR elements facing each other.

Further, in the above-mentioned first embodiment, the case where a pair of basic magnetically sensitive patterns are connected in series and one output terminal 8 is formed at the midpoint thereof has been described, but the present invention is not limited to this. It is also possible to connect a plurality of pairs of basic magnetically-sensitive patterns connected in series at positions separated by a predetermined integer multiple of λ to provide a plurality of output terminals. In this case, the sensitivity can be further increased as compared with the case of the pair of basic magnetic sensitive patterns alone.

In the first embodiment described above, the interval between the center lines is set to be half the magnetic pole width λ of the MR magnet 3, but the present invention is not limited to this. The distance between the center lines is defined as (m of the magnetic pole width λ of the MR magnet).
The width may be set to +1/2) times (m: integer).

Further, in the above-described first embodiment, the first magnetic sensitive pattern group 5A composed of the two basic magnetic sensitive patterns 4A and 4B and the second magnetic sensitive pattern composed of the two basic magnetic sensitive patterns 4C and 4D. The MR element 4 formed by connecting the pattern groups 5B in series will be described. Further, in the above-described second embodiment, the first basic magnetic patterns each having six basic magnetic sensitive patterns are described.
Magnetic sensitive pattern group 11A and second magnetic sensitive pattern group 11B
Although the MR element 10 formed by serially connecting and is described above, the present invention is not limited thereto, and any series of first and second magnetic sensitive pattern groups having even basic magnetic sensitive patterns may be used. . At this time, the basic magnetic sensitive patterns forming the first and second magnetic sensitive pattern groups are the number of basic magnetic sensitive patterns arranged at positions of even multiples of the magnetic pole width λ from an arbitrary reference point, and the magnetic pole width λ. And the number of basic magnetically sensitive patterns arranged at odd multiples of. Here, the numbers of basic magnetic sensitive patterns forming the first magnetic sensitive pattern group and the second magnetic sensitive pattern group do not have to be equal as long as they are even numbers.

Further, in the above-mentioned first and second embodiments, the case where the present invention is applied to the one-phase MR sensor has been described, but the present invention is not limited to this, and two-phase, three-phase, multi-phase, etc. When used for a phase MR sensor, the linearity near the center of the output is improved, and the detection accuracy can be further improved.

In the above-mentioned first and second embodiments, the case where the MR magnet, which is a rotary drum, is rotated in order to generate the relative position movement between the MR magnet and the MR element has been described. The invention is not limited to this, and the change in the magnetic field may be detected from the relative position movement due to the linear movement, as in the case of a linear motor, for example. Further, since the position movement between the MR magnet and the MR element is relative, the MR magnet or M
Any of the R elements may move its position.

[0034]

As described above, according to the present invention, the magnet means extends in a direction substantially orthogonal to the arrangement direction of the N and S poles, and has a magnetic pole width in the arrangement direction of the N and S poles. 0.3 ~ 1
The first and second magnetic sensitive patterns, which are a plurality of basic magnetic sensitive patterns in which the folded strip-shaped patterns of the magnetoresistive elements having the double magnetic sensitive pattern width, are formed in the magnetic pole width of (m + 1) in the arrangement direction of the magnet means. / 2) are arranged in series at double intervals, and a DC voltage is applied to both ends of the first and second magnetic sensitive patterns, and a magnetic resistance element that obtains an output using the connection point as an output terminal is provided. It is possible to realize a magnetoresistive sensor capable of improving the detection accuracy and the AM fluctuation due to the output waveform of the MR output regardless of the length of the gap between the resistance element and the magnet means.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a magnetoresistive sensor according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an MR element.

FIG. 3 is a schematic diagram showing an MR element.

FIG. 4 is a signal waveform diagram showing the experimental results of the magneto-sensitive pattern width of the MR element and the curvature near the center generated in the MR output.

FIG. 5 is a signal waveform diagram showing experimental results of the magneto-sensitive pattern width of the MR element and the curvature near the center generated in the MR output.

FIG. 6 is a signal waveform diagram showing the experimental results of the magneto-sensitive pattern width of the MR element and the curvature near the center generated in the MR output.

FIG. 7 is an output diagram showing experimental results of the magneto-sensitive pattern width of the MR element and the MR output.

FIG. 8 is an output diagram showing experimental results of the magneto-sensitive pattern width of the MR element, MR output, and AM fluctuation.

FIG. 9 is a schematic diagram showing an MR element of a second embodiment.

FIG. 10 is a schematic diagram showing the shape and magnetic field direction of a basic magnetically sensitive pattern.

FIG. 11 is a schematic diagram showing a modified example of the magneto-sensitive pattern of the MR element.

FIG. 12 is a signal waveform diagram showing an experimental result of bending near the center generated in the MR output detected by the MR sensor.

FIG. 13 is a schematic diagram showing MR output in a three-phase MR sensor.

[Explanation of symbols]

1 ... MR sensor, 2 ... magnetic drum, 3 ... MR magnet, 4, 10 ... MR element, 5A, 11A ... 1st
Magnetic sensitive pattern group 5B, 11B: second magnetic sensitive pattern group 6, ground terminal, 7 power supply voltage terminal, 8 output terminal.

Claims (3)

[Claims] 1. A magnet means having a predetermined magnetic pole width and a plurality of N poles and S poles continuously magnetized at equal intervals, and a magnetoresistive element are arranged face-to-face, and the magnet means and the magnetoresistive element are arranged. In the magnetoresistive sensor which detects the change in the magnetic field due to the change in the movement of the relative position with respect to the magnetoresistive element and outputs it as the change in the voltage, the magnetoresistive element includes the N pole and the S pole A folded strip-shaped pattern of a magnetoresistive element is formed which extends in a direction substantially orthogonal to the arrangement direction and has a magneto-sensitive pattern width of 0.3 to 1 times the magnetic pole width in the arrangement direction of the N pole and the S pole. A first and a second magnetic sensitive pattern composed of a plurality of basic magnetic sensitive patterns are formed in the magnetic pole width (m +) in the arrangement direction of the magnet means.
A magnetoresistive sensor characterized by being arranged in series at intervals of 1/2) times and connected in series to apply a DC voltage to both ends of the first and second magnetic sensing patterns, and obtaining an output using the connection point as an output terminal. . 2. The first and second magnetic sensing patterns, a plurality of basic magnetic sensing patterns provided at arbitrary positions represented by an even multiple of the magnetic pole width from a predetermined reference point, and the plurality of basic magnetic sensing patterns. The magnetic resistance according to claim 1, further comprising a plurality of basic magnetic sensing patterns which are provided in the same number as the magnetic sensing patterns and which are provided at arbitrary positions represented by an odd multiple of the magnetic pole width from the reference point. Sensor. 3. The magnetoresistive sensor according to claim 1, wherein the magnetic sensing pattern width is 0.3 times the magnetic pole width.