JP4487093B2 - Magnetic sensor - Google Patents

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 object, and more particularly, a fundamental wave of an actual output signal detected by the arrangement of magnetoresistive elements. The present invention relates to a magnetic sensor capable of canceling a harmonic component superimposed on a component.

  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, Displacement amount is obtained by arranging four magnetoresistive elements at a pitch narrower than the pitch of multipolar magnetization in this magnetic sensor and detecting the resistance value of the magnetoresistive element that changes due to the rotation of the movable object to be detected. Is detected.

  In such a magnetic sensor, when detecting the position of the movable detection object, sinusoidal signals (sin θ and cos θ) output from the A-phase sensor and the B-phase sensor provided corresponding to the displacement of the movable detection object are used. The displacement is detected by using the obtained arc tangent signal of both signals obtained by the following equation.

  Therefore, the cleanliness of the sinusoidal A-phase signal and B-phase signal output from the A-phase sensor and the B-phase sensor is closely related to the accuracy of the magnetic scale (magnetic sensor). Therefore, it is required to obtain a smooth signal that is less affected by distortion due to saturation of the magnetoresistive change.

  In recent years, an output signal from a magnetic sensor is generally formed from a fundamental wave component and a harmonic component superimposed on the fundamental wave component. There is a technique for canceling a wave (see, for example, Patent Document 1).

  According to the invention disclosed in Patent Document 1, when the magnetoresistive elements are arranged on the magnetic sensor arranged to face the multipolar magnetized layer, they are arranged in parallel at a predetermined interval. Thus, it is possible to cancel out at least one odd harmonic component caused by saturation of the magnetoresistive change in reverse phase, and to obtain a smooth sine wave output signal.

More specifically, in FIG. 10, magnetoresistive elements R _{101 to} R ₁₀₄ are arranged side by side at intervals shown in the figure on a magnetic sensor 100 arranged to face the magnetic scale 200 magnetized with a pitch λ. Thus, the third harmonic and the fifth harmonic can be canceled out.

Japanese Patent No. 2529960 (FIG. 10)

  However, in the invention described in Patent Document 1, in canceling the third harmonic and the fifth harmonic, the same number (two in FIG. 10) of magnetoresistive elements for both harmonics. However, this causes the following problems.

First, the problem of uniform thermal characteristics arises. That is, in FIG. 10, in order to cancel the fifth harmonic, it is necessary to leave the distance between R ₁₀₁ and R ₁₀₃ and the distance between R ₁₀₂ and R ₁₀₄ by (λ / 2 + λ / 10), Due to this interval, there arises a problem that the thermal characteristics of the magnetoresistive elements R _{101 to} R ₁₀₄ cannot be made uniform. For example, in FIG. 10, it is considered that this is a problem solved by narrowing the interval between the magnetoresistive elements by arranging three or more magnetoresistive elements. However, if the third and fifth harmonics are canceled out by the same number of magnetoresistive elements of three or more, the spacing between the magnetoresistive elements may be extremely narrow, which makes manufacturing difficult. This may lead to an increase in manufacturing cost.

  On the other hand, when the third harmonic and the fifth harmonic are canceled by the arrangement of the three or more magnetoresistive elements, due to the mutual interference of the output signals obtained from the plurality of magnetoresistive elements, Unexpected harmonics such as the seventh harmonic and the ninth harmonic are canceled out, which can contribute to further improvement in identification accuracy. However, in the invention described in Patent Document 1, since the number of magnetoresistive elements for canceling each harmonic is constant, the interval between the magnetoresistive elements as a whole becomes extremely narrow, which makes it difficult to manufacture and the manufacturing cost. The problem that it leads to the rise of is caused.

  Thus, from the viewpoint of achieving uniform thermal characteristics and improving identification accuracy, it is desirable to increase the number of magnetoresistive elements that cancel each harmonic, but in the invention described in Patent Document 1, each harmonic is Since the number of magnetoresistive elements to be canceled is constant, as a result, if the number of magnetoresistive elements is increased, the manufacturing becomes difficult and the manufacturing cost increases.

  The present invention has been made in view of such a point, and the object thereof is to flexibly adjust the interval between the magnetoresistive elements and to cancel the harmonics to such an extent that they are not difficult to manufacture. It is an object of the present invention to provide a magnetic sensor capable of increasing the thermal conductivity and, in turn, achieving uniform thermal characteristics and improving identification accuracy.

  In order to solve the above-described problems, the present invention provides a magnetic sensor having a magnetoresistive pattern formed by arranging a magnetoresistive element that detects a magnetic field of a magnetic scale. When the number of magnetoresistive elements that remove harmonic components superimposed on the wave components is L, the L magnetoresistive elements are arranged at a predetermined interval P.

  More specifically, the present invention provides the following.

(1) In a magnetic sensor having a magnetoresistive pattern formed by arranging magnetoresistive elements made of magnetoresistive thin films on a substrate at a predetermined interval in order to detect a magnetic field of a magnetic scale, the output of the magnetoresistive pattern When the number of the magnetoresistive elements that remove the harmonic component superimposed on the fundamental wave component of the signal is L, the L magnetoresistive elements are relative to each other on the magnetic scale at an interval P calculated by the following equation. A magnetic sensor, which is sequentially arranged in a moving direction.
P = nλ / mL
m: order of harmonic component to be removed, λ: wavelength of fundamental component of output signal n: natural number

  According to the present invention, in a magnetic sensor having a magnetoresistive pattern formed by arranging magnetoresistive elements made of a magnetoresistive thin film on a substrate at a predetermined interval, a displacement detection signal serving as an output signal of the magnetoresistive pattern When the number of magnetoresistive elements that remove harmonic components superimposed on the fundamental wave component of L is L, the L magnetoresistive elements are P = nλ / mL (m: order of removed harmonic components, λ: output Arranged sequentially in the relative movement direction of the magnetic scale (in the direction substantially perpendicular to the longitudinal direction of the magnetoresistive element) at the interval P calculated by the calculation formula of the wavelength of the fundamental wave component of the signal, n: natural number. Therefore, the m-th harmonic can be removed by superimposing (summing) the displacement detection signals obtained from the L magnetoresistive elements, thereby improving the identification accuracy.

  In addition, the number of magnetoresistive elements that cancel each harmonic does not need to be constant as in the prior art, and the number of magnetoresistive elements that cancel each harmonic is flexibly changed, and the interval between the magnetoresistive elements is flexibly changed. Since it can be adjusted, the number of magnetoresistive elements that cancel each harmonic can be increased to the extent that it is not difficult to manufacture, and as a result, the thermal characteristics can be made uniform.

(2) In a magnetic sensor having a magnetoresistive pattern formed by arranging magnetoresistive elements made of magnetoresistive thin films on a substrate at a predetermined interval in order to detect a magnetic field of a magnetic scale, the output of the magnetoresistive pattern Of the plurality of harmonic components superimposed on the fundamental component of the signal, the number of the magnetoresistive elements for removing one odd-order harmonic component is L ₁ , and one odd-order harmonic other than the one odd-order harmonic component is L ₁ . When the number of the magnetoresistive elements for removing the wave component is L ₂ (L1 ≠ L2) , the L ₁ magnetoresistive elements move relative to each other at the interval P ₁ calculated by the following equation. It arranged one after the other in the direction, the magnetic resistance pattern, turn the magnetoresistive element of the L ₁ present, relatively, at intervals P ₂ calculated by the following equation, the relative movement direction of the magnetic scale Before A magnetic sensor characterized in that it is formed by L ₂ sets arranged.
P ₁ = nλ / mL ₁
P ₂ = nλ / mL ₂
m: order of harmonic component to be removed, λ: wavelength of fundamental component of output signal n: natural number

According to the present invention, in a magnetic sensor that detects a magnetic field of a magnetic scale, the number of magnetoresistive elements that remove one harmonic component from a plurality of harmonic components superimposed on a fundamental component of an output signal of a magnetoresistive pattern. when the as _{L 1,} and the number of the magnetoresistive element to remove the first harmonic component other than higher harmonic component of the 1 and _{L 2,} the magnetoresistive element of _{one L is, P 1 = nλ / mL 1} (m : order of the harmonic components removed, lambda: the wavelength of the fundamental wave component of the output signal, n: at intervals P ₁ calculated by the calculation formula for a natural number), longitudinal (magneto resistive element in the relative movement direction of the magnetic scale and while being arranged in a direction) turn substantially perpendicular magnetoresistance pattern, the magnetoresistive element of their L ₁ present, _{relatively, P 2 = nλ / mL 2} (m: harmonic component removing Order, λ: Base of output signal Wavelength of the wave components, n: at intervals P ₂ calculated by the calculation formula of the natural numbers), because it was decided to be formed by the magnetic scale of set L ₂ one after the other in the relative movement direction arrangement, L ₁ present Canceling one harmonic component other than the one harmonic component by canceling one harmonic component by one magnetoresistive element, and arranging _two L sets of the _one magnetoresistive element. it can.

Therefore, a plurality of harmonic components can be removed by superimposing displacement detection signals obtained from a total of (L ₁ × L ₂ ) magnetoresistive elements, and thus the identification accuracy can be improved.

(3) In a magnetic sensor having a magnetoresistive pattern formed by arranging magnetoresistive elements made of magnetoresistive thin films on a substrate at a predetermined interval in order to detect a magnetic field of a magnetic scale, The magnetoresistive pattern is formed by combining the intervals P of the magnetoresistive elements set as in the following expression in order to remove at least two or more harmonic components from the fundamental wave component of the output signal of Magnetic sensor to do.
P = nλ / mL
m: Order of harmonic component to be removed, λ: Wavelength of fundamental wave component of output signal L: Number of magnetoresistive elements for removing harmonic component of order m (provided that at least one of L ≠ 2 is included)
n: natural number

  According to the present invention, in the magnetic sensor, P = nλ / mL (m: the order of the removed harmonic component, λ, in order to remove at least two harmonic components from the fundamental component of the output signal of the magnetoresistive pattern described above. : The wavelength P of the fundamental wave component of the output signal, n: a natural number) is combined to form the magnetoresistive pattern by combining the intervals P, so that a plurality of magnetoresistive elements can be combined by combining a plurality of magnetoresistive elements. Harmonic components can be canceled at once, and thus the identification accuracy can be improved.

(4) Two sets of the magnetoresistive patterns are arranged in the relative movement direction of the magnetic scale at the interval P ′ calculated by the following formula and are electrically connected in series. A magnetic sensor characterized by taking out an output signal from an electrical contact.
P ′ = nλ / m ′
m ′ : the order of even harmonic components to be removed, λ: wavelength of the fundamental component of the output signal, n: natural number

According to the present invention, the above-described magnetoresistive pattern, that is, L ₁ magnetoresistive elements are arranged at the interval P ₁ , and the L ₁ magnetoresistive elements are relatively arranged at the interval P ₂ . The magnetoresistive pattern formed by arranging _two sets of L is calculated by an equation of P ′ = nλ / m (m: order of harmonic component to be removed, λ: wavelength of fundamental component of output signal, n: natural number). Since two sets are arranged in the relative movement direction of the magnetic scale at the interval P ′ and are electrically connected in series, the output signal is taken out from the electrical contacts of the two sets of magnetoresistive patterns. A plurality of harmonic components can be removed by the sum and difference of displacement detection signals obtained from a total of {(L ₁ × L ₂ ) × 2} magnetoresistive elements, and thus the identification accuracy can be improved.

  In addition, according to the present invention, the harmonic components are removed by the sum and difference of the displacement detection signals obtained from a number of magnetoresistive elements, so that the higher-order harmonic components are canceled by the mutual interference of these displacement detection signals. This can contribute to further improvement of identification accuracy.

(5) Two sets of the magnetoresistive patterns are arranged in the relative movement direction of the magnetic scale at the interval P ′ calculated by the following equation, and are electrically connected in parallel. A magnetic sensor characterized in that an output signal is extracted from each of the symmetry points.
P ′ = nλ / m ′
m ′ : the order of even harmonic components to be removed, λ: wavelength of the fundamental component of the output signal, n: natural number

According to the present invention, the above-described magnetoresistive pattern, that is, L ₁ magnetoresistive elements are arranged at the interval P ₁ , and the L ₁ magnetoresistive elements are relatively arranged at the interval P ₂ . The magnetoresistive pattern formed by arranging _two sets of L is calculated by an equation of P ′ = nλ / m (m: order of harmonic component to be removed, λ: wavelength of fundamental component of output signal, n: natural number). Two sets are arranged in the relative movement direction of the magnetic scale at the interval P ′ and are electrically connected in parallel, and the output signal is taken out from the respective symmetry points of the two sets of magnetoresistive patterns. A plurality of harmonic components can be removed by the sum and difference of displacement detection signals obtained from a total of {(L ₁ × L ₂ ) × 2} magnetoresistive elements, thereby improving the identification accuracy.

Here, the "point of symmetry" of two sets of magneto-resistive pattern, of the magnetoresistive element sum L ₁ present are connected in series, connected in series one (L _1/2) and the magnetoresistive element of the present , series-connected other (L _1/2) means and the magnetoresistive element of this, the electrical connection points of the.

(6) In a magnetic sensor having a magnetoresistive pattern formed by arranging magnetoresistive elements made of magnetoresistive thin films on a substrate at a predetermined interval in order to detect a magnetic field of a magnetic scale, the output of the magnetoresistive pattern A magnetic sensor, wherein a width W of the magnetoresistive element in a relative movement direction of the magnetic scale is set to a width W calculated by the following equation in order to remove a harmonic component superimposed on a fundamental wave component of a signal.
W = nλ / m
m: order of harmonic component to be removed, λ: wavelength of fundamental component of output signal n: natural number

According to the present invention, in the magnetic sensor for detecting the magnetic field of the magnetic scale, in order to remove the harmonic component superimposed on the fundamental wave component of the output signal of the magnetoresistive pattern, the magnetoresistive element in the relative movement direction of the magnetic scale is removed. Since the width is set to the width W calculated by the calculation formula of W = nλ / m (m: the order of the harmonic component to be removed, λ: the wavelength of the fundamental wave component of the output signal, n: natural number), was the L ₁ present magnetoresistive element, can be replaced by a single magnetoresistive element.

  Accordingly, by realizing cancellation of harmonic components with a single magnetoresistive element, it is possible to remove harmonics and improve identification accuracy, and to simplify the structure.

  As described above, the magnetic sensor according to the present invention can cancel each harmonic component while flexibly adjusting the interval between the magnetoresistive elements, so that the number of magnetoresistive elements is increased to the extent that it is not difficult to manufacture. In addition to improving the identification accuracy, it can also contribute to uniform thermal characteristics.

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

[Schematic structure]
FIG. 1 is a diagram showing a schematic structure of a magnetic sensor 1 according to an embodiment of the present invention.

  In FIG. 1, first, the opposing arrangement relationship between the magnetic sensor 1 that determines the waveform phase of the displacement detection signal output from the magnetic sensor 1 and the magnetic scale 2 of the detected object will be described.

In FIG. 1, the magnetic scale 2 is provided with magnetized magnets in which N poles and S poles are alternately arranged at a pitch λ. That is, the pitch from the N pole to the N pole and the pitch from the S pole to the S pole are both λ. On the other hand, in the magnetic sensor 1, the four magnetoresistives R _{1 to} R ₄ are arranged in this order so that the pitch with the adjacent magnetoresistor is λ / 4, λ / 4, λ / 4. Are arranged in parallel with each other.

A bias voltage source V _cc is connected to one terminal of each of the magnetic resistors R _{1 to} R ₄ via the power supply line 3. On the other hand, each displacement detection signal is output from the other terminal of each of the magnetic resistances R _{1 to} R ₄ . That is, the magnetoresistance _{R 1} to + a phase signal, from reluctance _{R 2} + b-phase signal, -a phase signal from the magnetic resistance _{R 3,} -b phase signal from the magnetic resistance _{R 4,} the displacement detecting signal picked Will be. Note that a bias magnetic field is applied to the magnetic sensor 1.

Since the magnetic sensor 1 and the magnetic scale 2 of the object to be detected are in the above-described facing relationship, the waveform phase of the displacement detection signal output from the magnetic sensor 1 is determined as follows. That is, since the pitch between the magnetic resistance R ₁ and the magnetic resistance R ₃ is λ / 2, the resistance value of both changes with a phase difference of 180 ° depending on the magnetic field received from the magnetic scale 2 of the detected object. Accordingly, the signal waveform of the + a phase signal extracted from the magnetic resistance R ₁ and the signal waveform of the −a phase signal extracted from the magnetic resistance R ₃ are shifted in phase by 180 °. Further, since the pitch between the magnetic resistance R ₂ and the magnetic resistance R ₄ is also λ / 2, the signal waveform of the + b phase signal extracted from the magnetic resistance R ₂ and the −b phase extracted from the magnetic resistance R ₄ as described above. The signal waveform of the signal has a phase shifted by 180 °.

Further, since the pitch between the magnetic resistance R ₁ and the magnetic resistance R ₂ is λ / 4, the resistance value of both changes with a phase difference of 90 ° by the magnetic field received from the magnetic scale 2 of the detection object. Therefore, the signal waveform of the + a phase signal extracted from the magnetic resistance R ₁ and the signal waveform of the + b phase signal extracted from the magnetic resistance R ₂ are out of phase by 90 °. Further, since the pitch between the magnetic resistance R ₃ and the magnetic resistance R ₄ is also λ / 4, the signal waveform of the −a phase signal extracted from the magnetic resistance R ₃ and the −b extracted from the magnetic resistance R ₄ as described above. The signal waveform of the phase signal has a phase shifted by 90 °.

  The signal waveforms of the displacement detection signals described above are ideally as shown in FIG. In other words, considering the waveform of the + a phase signal as a reference (FIG. 2A), the + b phase signal has a waveform as shown in FIG. The a-phase signal has a waveform as shown in FIG. 2C with a phase shift of 180 ° from the waveform of the + a-phase signal, and the -b-phase signal has a phase shift of 270 ° with respect to the waveform of the + a-phase signal. The waveform is as shown in d).

  Here, in FIG. 2, an ideal (smooth) waveform is considered for each displacement detection signal, but in general, a harmonic component other than the fundamental wave component is superimposed on the actual displacement detection signal. More specifically, a description will be given with reference to FIG. FIG. 3 is a graph showing a change characteristic of the resistance R of the magnetoresistive element with respect to the input magnetic field H from the magnetic scale 2.

In FIG. 3, when the absolute value of the input magnetic field from the magnetic scale 2 gradually increases from 0, the resistance value of the magnetoresistive element usually decreases, but when the absolute value of the input magnetic field exceeds a certain magnetic field H ₁ , The resistance value of the magnetoresistive element is saturated (X portion in FIG. 3). Therefore, due to the effect of the saturation of the resistance value, the ideal waveform of each displacement detection signal shown in FIG. 2 is actually a waveform as shown in FIG. In FIG. 4, only the waveform of the + a phase signal in FIG. 2 is extracted and enlarged, but the displacement detection signals of the + b phase signal, the −a phase signal, and the −b phase signal are also phase-shifted. The same can be said for the only difference.

  In FIG. 4, the displacement detection signal actually obtained shown in FIG. 4 (a) includes the fundamental wave component shown in FIG. 4 (b), the second harmonic component shown in FIG. 4 (c), and FIG. The third harmonic component shown in (d), the fourth harmonic component shown in FIG. 4 (e), the fifth harmonic component shown in FIG. 4 (f), and other high-order harmonic components It is expressed by the superposition of Therefore, if the second and subsequent harmonic components are removed, a displacement detection signal having a smooth waveform like the fundamental component shown in FIG. 4B can be obtained.

[Magnetic resistance pattern formation]
FIG. 5 is a diagram showing an example of a magnetoresistive pattern formation mode of the magnetic sensor 1 according to the embodiment of the present invention. Each of the above-described magnetic resistances R _{1 to} R ₄ corresponds to the magnetic resistance pattern shown in FIG. In the magnetoresistive pattern shown in FIG. 5A, the six magnetoresistive elements R _{11 to} R ₁₆ cancel the fifth harmonic component in the set of three and cancel the third harmonic component in the set of two. Therefore, the intervals calculated by the formulas of P = nλ / mL (m: order of harmonic component to be removed, λ: wavelength of fundamental component of output signal, L: number of harmonic components to cancel, n = 1), respectively Thus, the magnetic scales 2 of the detection target are sequentially arranged in the relative movement direction, and are electrically connected in series by a conductor. Here, n = 1, but the present invention is not intended to limit n to this, and may be n = 2 or n = 3, for example. Specifically, it demonstrates using FIG.5 (b)-FIG.5 (f).

First, the principle of canceling the fifth harmonic component with three sets will be described. In three sets of magneto-resistive elements R ₁₁ to R _13, spacing of the magnetoresistive element R ₁₁ and R _12, spacing of the magnetoresistive element R ₁₂ and R ₁₃ substitutes m = 5, L = 3 in the above formula , Both are P ₅ (= λ / 5 × 3) (FIG. 5B).

When the fundamental component of the displacement detection signal obtained from the portion of the magnetoresistive element R ₁₁ is sin θ by arranging the magnetoresistive elements R _{11 to} R ₁₃ at this interval P ₅ , as shown in the following formula, the magnetism magnetoresistance and the fifth harmonic component sin5θ displacement detection signals obtained from the portion of the resistive element R _11, displacement detection signal and the phase obtained from the portion of the magneto-resistive element R ₁₁ is displaced by 2π / (5 × 3) a device 5th harmonic component of the displacement detection signal obtained from the portion of _{R 12 sin5 {θ + 2π /} (5 × 3)}, the displacement detection signal and the phase obtained from the portion of the magneto-resistive element R ₁₁ is {2 [pi / ( 5th harmonic component sin5 {θ + 2π / (5 × 3) + 2π / (5 × 3) of the displacement detection signal obtained from the portion of the magnetoresistive element R ₁₃ shifted by 5 × 3) + 2π / (5 × 3)}. )} And the magnetoresistive element R ₁₁ The fifth harmonic component of the displacement detection signal when the to R ₁₃ connected in series becomes zero.

Also in the three sets of magneto-resistive elements R ₁₄ to R _16, interval of the magneto-resistive element R ₁₄ and R _15, spacing of the magnetoresistive element R ₁₅ and R ₁₆ are, in the above formula m = 5, L = 3 Is substituted for P ₅ (= λ / 5 × 3) (FIG. 5C). As described above, by arranging the magnetoresistive elements R _{14 to} R ₁₆ at the interval P ₅ , the fifth-order harmonic component becomes zero, but the principle is the same as described above, and the description thereof is omitted.

The reason why not only three sets of magnetoresistive elements R _{11 to} R ₁₃ but also three sets of magnetoresistive elements R _{14 to} R ₁₆ is required is that the third harmonic component is 2 as described below. This is to cancel with this set.

The principle of canceling the third harmonic component with two sets will be described. In two sets of magneto-resistive elements R ₁₁ and R _14, spacing of the magnetoresistive element R ₁₁ and R ₁₄ substitutes the m = 3, L = 2 in the above _{equation, P 3 (= λ / 3} × 2) (FIG. 5D).

When the fundamental wave component of the displacement detection signal obtained from the portion of the magnetoresistive element R ₁₁ is sin θ, by arranging the magnetoresistive elements R ₁₁ and R ₁₄ at this interval P ₃ , magnetoresistance and a third harmonic component sin3θ displacement detection signals obtained from the portion of the resistive element R _11, displacement detection signal and the phase obtained from the portion of the magneto-resistive element R ₁₁ is displaced by 2π / (3 × 2) Displacement when the magnetoresistive elements R ₁₁ and R ₁₄ are connected in series by superimposing the third harmonic component sin 3 {θ + 2π / (3 × 2)} of the displacement detection signal obtained from the element R _14. The third harmonic component of the detection signal becomes zero.

Also in the two sets of magneto-resistive elements R ₁₂ and R _15, spacing of the magnetoresistive element R ₁₂ and R ₁₅ substitutes the m = 3, L = 2 in the above _{equation, P} 3 (= _λ / 3 X2) (FIG. 5E). Also in the two sets of magneto-resistive elements R ₁₃ and R _16, interval of the magneto-resistive element R ₁₃ and R ₁₆ substitutes the m = 3, L = 2 in the above _{equation, P 3 (= λ / 3} × 2 (FIG. 5 (f)). As described above, by arranging the magnetoresistive elements R ₁₂ and R ₁₅ and the magnetoresistive elements R ₁₃ and R ₁₆ at this interval P ₃ , the third harmonic component becomes zero. The description is omitted because it is similar.

As described above, the six magnetoresistive elements R _{11 to} R ₁₆ are arranged at the intervals shown in FIG. 5A that satisfy all the requirements for the intervals shown in FIGS. 5B to 5F. According to the formed magnetoresistive pattern, the third harmonic component and the fifth harmonic component can be canceled, and as a result, a displacement detection signal having a smooth waveform such as a fundamental wave component can be obtained. .

  In addition, it is arbitrary how many magnetoresistive elements are used to cancel the third harmonic component and the fifth harmonic component, and it is difficult to manufacture while flexibly adjusting the interval between the magnetoresistive elements. The number of magnetoresistive elements that cancel out the third harmonic component and the fifth harmonic component can be increased to the extent that it does not occur, and thus the thermal characteristics can be made uniform and the identification accuracy improved.

  Furthermore, in the present embodiment, two types of harmonic components are canceled, but considering the same as above, it is also possible to cancel a plurality of types of harmonic components such as three types and four types at a time.

  FIG. 6 is a diagram showing another example of a magnetoresistive pattern forming mode of the magnetic sensor 1 according to the embodiment of the present invention.

In the magnetoresistive pattern shown in FIG. 6A, the six magnetoresistive elements R _{11 to} R ₁₆ cancel out the third harmonic component with three sets and cancel the fifth harmonic component with two sets. Therefore, the magnetic scale 2 of the object to be detected at intervals calculated by the following formulas: P = nλ / mL (m: order of harmonic component to be removed, λ: wavelength of fundamental wave component of output signal, n = 1) Are sequentially arranged in the relative movement direction, and are electrically connected in series by a conductor. Note that although n = 1 here, the present invention is not intended to limit n to this, and for example, n = 2, n = 3, or any natural number may be used.

M More particularly, in three sets of magneto-resistive elements R _11, R _12, R _14, spacing of the magnetoresistive element R ₁₁ and R _12, spacing of the magnetoresistive element R ₁₂ and R ₁₄ are, in the above formula = 3 and L = 3 are substituted, and both become P ₃ (= λ / 3 × 3) (FIG. 6B). Also in the three sets of magneto-resistive elements R _13, R _15, R _16, interval of the magneto-resistive element R ₁₃ and R _15, spacing of the magnetoresistive element R ₁₅ and R ₁₆ are, in the above formula m = 3, Substituting L = 3, both become P ₃ (= λ / 3 × 3) (FIG. 6C). Thus, by arranging the magnetoresistive elements R ₁₁ , R ₁₂ , and R ₁₄ and the magnetoresistive elements R ₁₃ , R ₁₅ , and R ₁₆ at the intervals P ₃ , the third harmonic component is reduced to zero. Can be. The principle is the same as described above.

Meanwhile, in the two sets of magneto-resistive elements R ₁₁ and R _13, spacing of the magnetoresistive element R ₁₁ and R ₁₃ substitutes m = 5, L = 2 in the above _{equation, P} 5 (= _λ / 5 × 2) (FIG. 6D). Also in the two sets of magneto-resistive elements R ₁₂ and R _15, spacing of the magnetoresistive element R ₁₂ and R ₁₅ substitutes m = 5, L = 2 in the above _{equation, P} 5 (= _λ / 5 X2) (FIG. 6E). Also in the two sets of magneto-resistive elements R ₁₄ and R _16, interval of the magneto-resistive element R ₁₄ and R ₁₆ substitutes m = 5, L = 2 in the above _{equation, P 5 (= λ / 5} × 2 (FIG. 6 (f)). In this manner, by arranging the magnetoresistive elements R ₁₁ and R ₁₂ , the magnetoresistive elements R ₁₂ and R ₁₅ , and R ₁₄ and R ₁₆ with the interval P ₅ , the fifth harmonic component is obtained. Can be zero. The principle is the same as described above.

As described above, the six magnetoresistive elements R _{11 to} R ₁₆ are arranged at intervals shown in FIG. 6 (a) that satisfy all the requirements for the intervals shown in FIGS. 6 (b) to 6 (f). According to the formed magnetoresistive pattern, the third harmonic component and the fifth harmonic component can be canceled, and as a result, a displacement detection signal having a smooth waveform can be obtained.

  FIG. 7 is a diagram showing another example of a magnetoresistive pattern forming mode of the magnetic sensor 1 according to the embodiment of the present invention.

In the magnetoresistive pattern shown in FIG. 7A, the six magnetoresistive elements R _{11 to} R ₁₆ cancel out the second harmonic component in a set of three, and cancel the third harmonic component in a set of two. Therefore, the magnetic scale of the object to be detected at intervals calculated by the following expressions: P = nλ / mL (m: order of harmonic component to be removed, λ: wavelength of fundamental wave component of output signal, n = 1) 2 are sequentially arranged in the relative movement direction, and are electrically connected in series by a conductor. Here, n = 1, but the present invention is not intended to limit n to this, and may be n = 2 or n = 3, for example.

More specifically, in three sets of magneto-resistive elements R _11, R _13, R _15, spacing of the magnetoresistive element R ₁₁ and R _13, interval of the magneto-resistive element R ₁₃ and R ₁₅ are, m in the above formula = 2 and L = 3 are substituted, and both become P ₂ (= λ / 2 × 3) (FIG. 7B). Also in the three sets of magneto-resistive element R _12, R _14, R _16, magneto-resistive element spacing of R ₁₂ and R _14, interval of the magneto-resistive element R ₁₄ and R ₁₆ are the above equation with m = 2, Substituting L = 3, both become P ₂ (= λ / 2 × 3) (FIG. 7C). Thus, by arranging the magnetoresistive elements R ₁₁ , R ₁₃ , and R ₁₅ and the magnetoresistive elements R ₁₂ , R ₁₄ , and R ₁₆ at the intervals P ₂ , the third harmonic component is reduced to zero. Can be. The principle is the same as described above.

Meanwhile, in the two sets of magneto-resistive elements R ₁₁ and R _12, spacing of the magnetic resistance element R ₁₁ and R ₁₂ substitutes the m = 3, L = 2 in the above _{equation, P} 3 (= _λ / 3 × 2) (FIG. 7D). Also in the two sets of magneto-resistive elements R ₁₃ and R _14, interval of the magneto-resistive element R ₁₃ and R ₁₄ substitutes the m = 3, L = 2 in the above _{equation, P} 3 (= _λ / 3 X2) (FIG. 7E). Also in the two sets of magneto-resistive elements R ₁₅ and R _16, spacing of the magnetoresistive element R ₁₅ and R ₁₆ substitutes the m = 3, L = 2 in the above _{equation, P 3 (= λ / 3} × 2 (FIG. 7 (f)). Thus, by arranging the magnetoresistive elements R ₁₁ , R ₁₂ , the magnetoresistive elements R ₁₃ , R ₁₄ , R ₁₅ , R ₁₆ with the spacing P ₃ , the third harmonic component is obtained. Can be zero. The principle is the same as described above.

As described above, the six magnetoresistive elements R _{11 to} R ₁₆ are arranged at intervals shown in FIG. 7A that satisfy all the requirements for the intervals shown in FIGS. 7B to 7F. According to the formed magnetoresistive pattern, the third harmonic component and the fifth harmonic component can be canceled, and as a result, a displacement detection signal having a smooth waveform can be obtained.

  In the above-described magnetic pattern formation mode, the harmonic component is canceled by adjusting the interval between the magnetoresistive elements by the above equation P = nλ / mL. However, in the present invention, the line width is represented by the above equation W = nλ / m. The harmonic component may be canceled out by adjusting according to. For example, as shown in FIG. 8, when it is considered that the harmonic components are canceled out by two sets of magnetoresistive elements, these magnetoresistive elements must be arranged at intervals P (FIG. 8A). ), A single magnetoresistive element having the same line width as the interval P can be substituted (FIG. 8B). More specifically, one magnetoresistive element shown in FIG. 8B is considered to be a superposition of a plurality (numerous) of magnetoresistive elements having extremely narrow line widths in the direction of relative movement of the magnetic scale. Therefore, it is the same value as P when L = 1 is substituted into the above formula P = nλ / mL, and has the same function (function to cancel high frequency components) as the two magnetoresistive elements shown in FIG. It is possible to further reduce the size of the magnetic sensor while exhibiting this.

  5 to 7, the magnetoresistive pattern is formed by arranging each magnetoresistive element at an interval calculated by P = nλ / mL, and calculating the “sum of displacement detection signals” obtained from the respective portions. Each harmonic component is canceled by using the entire displacement detection signal. Next, each harmonic component is canceled by using the "displacement detection signal difference" as the entire displacement detection signal. , Will be described.

  FIG. 9 is a diagram showing another example of a magnetoresistive pattern forming mode of the magnetic sensor 1 according to the embodiment of the present invention.

  The magnetoresistive pattern shown in FIG. 9A is formed by arranging two sets of the magnetoresistive patterns shown in FIG. 5A in series, and taking out the displacement detection signal from the connection point, thereby obtaining each harmonic component. It is to cancel.

More specifically, the magnetoresistive pattern (six magnetoresistive elements R _{11 to} R ₁₆ ) shown on the left side of FIG. 9A cancels the fifth-order harmonic component with three sets, and with two sets. In order to cancel out the third harmonic component, the third harmonic component is arranged in the mode shown in FIG. Further, the magnetoresistive pattern (six magnetoresistive elements R _{17 to} R ₂₂ ) shown on the right side of FIG. 9A also cancels the fifth harmonic component with three sets, and the third harmonic with two sets. In order to cancel out the wave components, they are arranged in the manner shown in FIG. Further, the two sets of magnetoresistive patterns are electrically connected, and an output (displacement detection signal) Out is extracted from the connection point.

Here, the two sets of magnetoresistive patterns shown in FIG. 9 (a) have relatively two sets of P ′ = nλ / m (in order to cancel the second harmonic component and the fourth harmonic component). m: Order of harmonic components to be removed, arranged at intervals calculated by the equation of n = 1). That is, for example, when canceling the m-th harmonic component, it is relatively shifted by the wavelength of the m-th harmonic component (= λ / m), and the magnetoresistive elements R ₁₁ and R ₁₇ , the magnetoresistive element R ₁₂ and R ₁₈ , magnetoresistive elements R ₁₃ and R ₁₉ , magnetoresistive elements R ₁₄ and R ₂₀ , magnetoresistive elements R ₁₅ and R ₂₁ , and magnetoresistive elements R ₁₆ and R ₂₂ cancel out even harmonic components, respectively. It is arranged at an interval of P ′ = λ / m so that it is possible. At this time, not the wavelength of the m-th harmonic component (= λ / m), but the wavelength of the m-th harmonic component (= λ / m) and the half-wave of the fundamental wave (= λ / 2) It is also possible to adjust the interval by shifting. This is because the half wavelength (= λ / 2) of the fundamental wave is an integral multiple of the wavelength (= λ / m) of the second and subsequent m-th harmonic components (m is an even number of 2 or more).

  In this manner, the magnetoresistive elements in one magnetoresistive pattern are arranged at intervals of P = λ / mL, and the corresponding magnetoresistive elements in the other magnetoresistive pattern are P ′. By arranging at intervals of = λ / m, a plurality of harmonic components can be canceled at a time, and as a result, the identification accuracy can be greatly improved.

  In the same manner, not only canceling multiple harmonic components at a time by using the sum of displacement detection signals and the difference between displacement detection signals as the entire displacement detection signal, but also higher order due to mutual interference. A mode of forming a magnetoresistive pattern capable of canceling the harmonic component will be described.

  The magnetoresistive pattern shown in FIG. 9B is formed by arranging five magnetoresistive elements for canceling the third harmonic component at an interval of P = λ / (3 × 5). Two sets of resistance patterns are relatively arranged at a spacing P = λ / 2 + nλ (n: natural number), both magnetoresistive patterns are electrically connected in series, and an output (displacement detection signal) Out is taken out from the connection point. I am doing so.

The magnetoresistive pattern forming mode shown in FIG. 9C is for canceling the fifth harmonic component by two magnetoresistive elements for canceling the third harmonic component at intervals of P = λ / 3. Two sets of magnetoresistive elements formed by arranging two magnetoresistive elements at intervals of P = λ / (5 × 2) are relatively arranged at intervals of P = λ / 2 + nλ (n: natural number). Both magnetoresistive patterns are electrically connected in parallel, and outputs (displacement detection signals) Out ₁ and Out ₂ are taken out from the symmetrical points of the respective magnetoresistive patterns. Accordingly, by inputting the outputs (displacement detection signals) Out ₁ and Out ₂ to an external electronic circuit such as a differential amplifier, a plurality of harmonic components can be canceled.

  The connection method shown in FIG. 9C is merely an example in which a differential amplifier is used for the external electronic circuit, and other connection methods may be employed without departing from the spirit of the present invention. Is possible.

  In the magnetoresistive pattern forming mode shown in FIG. 9D, the two magnetoresistive elements shown in FIG. 9C are substituted with one magnetoresistive element having the same width as the interval. . According to this formation mode, since the structure is simple, the pattern can be arranged even if the magnetization pitch is reduced, and as a result, a high-resolution scale is possible.

  First, in the magnetoresistive pattern formation mode shown in FIG. 9A, the signal period λ was 0.8 mm, and the output (displacement detection signal) Out was measured. As a result, according to the magnetoresistive pattern formation mode shown in FIG. 9 (a), not only the third and fifth harmonics and the second and fourth harmonic components are canceled, but the magnetoresistive Due to the mutual interference of the displacement detection signals due to the 12 elements, all the 9th harmonic components were canceled and the 7th harmonic component was reduced by 72%. Thus, according to the magnetoresistive pattern formation mode shown in FIG. 9A, it can be seen that the total distortion up to the ninth harmonic component can be simultaneously reduced.

  Next, in the magnetoresistive pattern formation mode shown in FIG. 9B, the signal period λ was 0.8 mm, and the output (displacement detection signal) Out was measured. As a result, according to the magnetoresistive pattern formation mode shown in FIG. 9B, all the third-order and second-order and fourth-order harmonic components are canceled, and the fifth-order harmonic component is reduced by 80%. It was done. Further, the seventh harmonic component was reduced by 82% due to the mutual interference of the displacement detection signals due to the ten magnetoresistive elements. Thus, according to the magnetoresistive pattern formation mode shown in FIG. 9B, the seventh harmonic component can be significantly reduced as compared with the magnetoresistive pattern formation mode shown in FIG. 9A. I understand.

Next, in the magnetoresistive pattern formation mode shown in FIG. 9C, the signal period λ was set to 0.8 mm, and the differential outputs of outputs (displacement detection signals) Out ₁ and Out ₂ were measured. As a result, according to the magnetoresistive pattern formation mode shown in FIG. 9C, not only all the third and fifth harmonics and the second and fourth harmonic components are canceled, but also the magnetoresistive Due to the mutual interference of the displacement detection signals due to the eight elements, all the ninth harmonic components were canceled and the seventh harmonic components were reduced by 49%. Thus, according to the magnetoresistive pattern formation mode shown in FIG. 9C, it can be seen that the total distortion up to the ninth harmonic component can be simultaneously reduced.

Next, in the magnetoresistive pattern formation mode shown in FIG. 9D, the signal period λ was set to 0.8 mm, and the differential outputs of outputs (displacement detection signals) Out ₁ and Out ₂ were measured. As a result, according to the magnetoresistive pattern formation mode shown in FIG. 9D, the third and fifth harmonics and the second and fourth harmonic components were all canceled. Further, due to the mutual interference of the displacement detection signals due to the four magnetoresistive elements, the seventh harmonic component was reduced by 63% and the ninth harmonic component was reduced by 41%. Thus, according to the magnetoresistive pattern formation mode shown in FIG. 9D, it can be seen that the total distortion up to the ninth harmonic component can be simultaneously reduced.

  The magnetic sensor according to the present invention can increase the number of the magnetoresistive elements while flexibly adjusting the interval between the plurality of magnetoresistive elements, and thus can improve the identification accuracy and make the thermal characteristics uniform. Useful.

It is a figure which shows schematic structure of the magnetic sensor which concerns on embodiment of this invention. It is a wave form diagram which shows the signal waveform of the displacement detection signal obtained from the magnetic sensor which concerns on embodiment of this invention. 3 is a graph showing resistance R change characteristics of a magnetoresistive element with respect to an input magnetic field H from a magnetic scale 2; It is a figure which shows a mode that the displacement detection signal obtained from the magnetic sensor which concerns on embodiment of this invention is decomposed | disassembled into each component. It is a figure which shows an example of the formation aspect of the magnetoresistive pattern which the magnetic sensor which concerns on embodiment of this invention has. It is a figure which shows another example of the formation aspect of the magnetoresistive pattern which the magnetic sensor which concerns on embodiment of this invention has. It is a figure which shows another example of the formation aspect of the magnetoresistive pattern which the magnetic sensor which concerns on embodiment of this invention has. It is a figure which shows a mode that several magnetoresistive elements are substituted by one magnetoresistive element. It is a figure which shows another example of the formation aspect of the magnetoresistive pattern which the magnetic sensor which concerns on embodiment of this invention has. It is a figure which shows schematic structure of the conventional magnetic sensor.

Explanation of symbols

1 Magnetic sensor 2 Magnetic scale

Claims (3)

In order to detect the magnetic field of the magnetic scale, a magnetic sensor having a magnetoresistive pattern formed by arranging magnetoresistive elements made of magnetoresistive thin films on a substrate at predetermined intervals,
Of the plurality of harmonic components superimposed on the fundamental component of the output signal of the magnetoresistive pattern, the number of the magnetoresistive elements for removing one odd-order harmonic component is L ₁ , other than the odd-order harmonic component of that one When the number of the magnetoresistive elements that remove the odd-numbered higher harmonic component of 1 is L ₂ (L1 ≠ L2) ,
The L _one magnetoresistive elements are sequentially arranged in the relative movement direction of the magnetic scale at a distance P ₁ calculated by the following equation:
It said magnetoresistive pattern, the magnetoresistive element of the L ₁ present, relatively, at intervals P ₂ calculated by the following equation, to the set L ₂ arranged one after the other in the relative movement direction of the magnetic scale The magnetic sensor characterized by being formed by.
P ₁ = nλ / mL ₁
P ₂ = nλ / mL ₂
m: order of harmonic component to be removed, λ: wavelength of fundamental component of output signal n: natural number Two sets of the magnetoresistive patterns are arranged in the relative movement direction of the magnetic scale at an interval P ′ calculated by the following equation, and are electrically connected in series.
The magnetic sensor according to claim 1, wherein the extracting an output signal from the electrical contacts of the two sets of the magnetoresistive pattern.
P ′ = nλ / m ′
m ′ : the order of even harmonic components to be removed, λ: wavelength of the fundamental component of the output signal, n: natural number Two sets of the magnetoresistive patterns are arranged in the relative movement direction of the magnetic scale at an interval P ′ calculated by the following equation, and are electrically connected in parallel.
The magnetic sensor according to claim 1, wherein the extracting an output signal from each of the symmetry points of the two sets of the magnetoresistive pattern.
P ′ = nλ / m ′
m ′ : the order of even harmonic components to be removed, λ: wavelength of the fundamental component of the output signal, n: natural number

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