JP2008014954A - Magnetic sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To acquire a magnetic sensor having the magnetization direction easily identified when a voltage dividing circuit and a bridge circuit are assembled by combining a plurality of the magnetic sensors. <P>SOLUTION: A marking for identifying the magnetization direction of a fixed layer of a magnetoresistive effect element is indicated on a chip laid out with the magnetoresistive effect element and a plurality of connection pads connected to terminals of the magnetoresistive effect element. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a magnetic sensor using a magnetoresistive effect element that outputs an output signal in response to magnetism.

  Conventionally, a magnetic sensor using a magnetoresistive effect element that outputs an output signal in response to magnetism has been developed. The magnetoresistive element used in this magnetic sensor basically includes a free layer (free magnetic layer), a nonmagnetic layer, a fixed layer (pinned magnetic layer), an exchange bias layer (antiferromagnetic layer), It is comprised from the laminated structure of these. A bias magnetic field is applied to the fixed layer from the exchange bias layer, the fixed layer is magnetized by the exchange bias layer, and the magnetization direction is fixed in a specific direction. On the other hand, the magnetization direction of the free layer is changed by an external magnetic field.

In order to fix (pin) the magnetization direction of the fixed layer of the magnetoresistive element, it is necessary to adjust the lattice magnetization of the exchange bias layer. Therefore, a heat treatment is performed in which a magnetic field in a predetermined direction is applied to the exchange bias layer while being heated to a temperature called a blocking temperature at which the exchange anisotropic magnetic field disappears, and cooling is performed while the magnetic field is applied. (Patent Documents 1 and 2).
(Japanese Patent Laid-Open No. 2000-338211) (Japanese Patent Laid-Open No. 2000-256620)

  In the magnetic sensor using the magnetoresistive effect element, magnetoresistive effect elements having opposite directions in which the magnetization direction of the fixed layer forms 180 ° are connected in series, and a bridge circuit is configured using these elements. In this case, since the magnetization direction of the fixed layer of the magnetoresistive effect element connected in series is opposite to 180 °, the magnetization of the fixed layer needs to be performed in the opposite direction of 180 °.

  Conventionally, in order to magnetize a fixed layer of a magnetoresistive effect element, a current conducting conductor is provided for the magnetoresistive effect element formed on a single substrate, and a current is passed through the conductor. The generated magnetic field is applied to the magnetoresistive effect element, and the fixed layer is magnetized. In this method, since the amount of current to be passed through the conductor is limited, it is difficult to magnetize the fixed layer with a sufficiently large magnetic field. Therefore, the exchange anisotropic magnetic field cannot be increased, and the absolute value of the output signal from the magnetoresistive element cannot be increased. In addition, when used in a variable resistor, there has been a problem that the deviation of the reference change characteristic (output change characteristic with respect to the change amount) becomes large. This is presumably because it is difficult to make the magnetization direction of the fixed layer in a fixed direction because the exchange anisotropic magnetic field is small.

  Instead of this conductor magnetization method, a method has been developed in which an external magnetic field is applied to the magnetoresistive element and the fixed layer is magnetized. In this method, the external magnetic field can be increased and magnetized. However, the magnetization direction of adjacent magnetoresistive elements is opposite to 180 °, and the external magnetic field applied to one magnetoresistive element affects the other magnetoresistive element. This will limit the size of the magnetic field. For this reason, it has been difficult to magnetize the fixed layer of the magnetoresistive effect element with a sufficiently large magnetic field. Therefore, the absolute value of the output signal from the magnetoresistive element cannot be increased. When used for a variable resistor for the same reason as described above, there is a problem that a deviation from the reference change characteristic becomes large.

The fixed layer according to the above-described conventional example is generally made of α-Fe ₂ O ₃ and has a magnetization magnetic field of about 200 (KA / m). Recently, PtMn or the like is used for the fixed layer. , 600 (KA / m) is required to increase the exchange anisotropic magnetic field. However, as described above, when the bridge circuit is formed by the conventional external magnetic field magnetization method, the magnetization magnetic field affects between adjacent magnetoresistive elements, so the magnitude of the magnetization magnetic field is 200 (KA / m), and it is virtually impossible to increase to the required 600 (KA / m). Accordingly, the current situation is that the absolute value of the output signal from the magnetoresistive element cannot be increased, or the deviation from the reference change characteristic becomes large when used in a variable resistor.

  Furthermore, when a plurality of conventional magnetic sensors are combined to form a voltage dividing circuit or a bridge circuit, the magnetization direction of each magnetic sensor is unclear, so it is difficult to combine the magnetization directions in a predetermined direction. .

  An object of the present invention is to divide a voltage by combining a plurality of magnetic sensors that magnetize a fixed layer of a magnetoresistive effect element with a sufficiently large magnetizing magnetic field and output a large absolute value output signal from the magnetoresistive effect element. An object of the present invention is to obtain a magnetic sensor that can easily identify the magnetization direction of each magnetic sensor when assembling a circuit, a bridge circuit, or the like.

  The basic idea of the present invention is to provide markings for identifying the magnetization direction of the fixed layer of the magnetoresistive effect element on the chip, so that a plurality of chips can be easily identified with a predetermined magnetization direction. This facilitates the formation of a voltage dividing circuit and a bridge circuit for combining chips.

  On the basis of the basic idea, the magnetic sensor according to the present invention is configured to fix the magnetoresistive effect element on a chip on which a plurality of connection pads connected to the air resistance effect element and the terminals of the magnetoresistive effect element are formed. The marking for identifying the magnetization direction of the layer is displayed.

  It is preferable that the chip including the terminals of the magnetoresistive effect element, the plurality of connection pads, and the marking has a rectangular shape. It is preferable that the formation positions of the connection pads are aligned at symmetrical positions on two sides forming the corners of the chip, and these are connected by wire bonding. The marking can be formed in the vicinity of the corners facing the corners of the two sides.

  It is preferable that one chip has one magnetoresistive effect element, one set of connection pads and one marking, or at least two magnetoresistive effect elements, two sets of connection pads and one marking. .

  In the magnetic sensor of the present invention, four chips each having one magnetoresistive effect element are formed, and the magnetization directions of the fixed layers of adjacent magnetoresistive effect elements are different by 90 ° in the same rotation direction. Thus, it is possible to form a bridge circuit that outputs a one-phase output signal by connecting the magnetoresistive effect elements whose magnetization directions of the fixed layers are opposite to each other in series.

  In place of the bridge circuit, two chips each having one magnetoresistive effect element formed thereon are combined by changing the magnetization direction of the fixed layer of the magnetoresistive effect element by 180 °, and the magnetoresistive effect elements are connected in series. Thus, a voltage dividing circuit can be formed.

  Further, in place of the chip on which one magnetoresistive effect element is formed, four chips on which at least two magnetoresistive effect elements are formed are used, and the magnetization direction of the fixed layer of the magnetoresistive effect element is the same. Combining four chips so that their directions differ by 90 °, and connecting magnetoresistive elements whose magnetization directions of the fixed layers are opposite to each other in series to form a bridge circuit that outputs a multiphase output signal Can do.

  In addition, when combining chips having at least two magnetoresistive elements, two chips are used and the two chips are combined so that the magnetization directions of the fixed layers of the magnetoresistive elements differ by 180 °. A voltage dividing circuit may be formed by connecting magnetoresistive elements whose magnetization directions of the fixed layer are opposite to each other in series.

  According to the present invention, a pin having a large absolute value of an output signal from a magnetoresistive effect element is magnetized in a predetermined direction by magnetizing a fixed layer of the magnetoresistive effect element with a sufficiently large magnetizing magnetic field. Thus, a magnetic sensor can be obtained that can be easily combined.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  As shown in FIG. 7, the magnetoresistive effect element 1 that outputs an output signal in response to magnetism has an exchange bias layer (antiferromagnetic layer) 1a and a fixed layer (pinned magnetic layer) 1b as shown in FIG. And a magnetoresistive effect element which is a kind of GMR (Giant Magneto Resistance) element using a giant magnetoresistance effect, which is formed by laminating a nonmagnetic layer 1c and a free layer (free magnetic layer) 1d on a substrate 2. It is configured as.

  In order for the magnetoresistive element 1 to exhibit a giant magnetoresistive effect, for example, the exchange bias layer 1a is a Pt-Mn layer, the fixed layer 1b is a NiFe layer, the nonmagnetic layer 1c is a Cu layer, and the free layer 1d is a NiFe layer. However, the present invention is not limited to these, and any material may be used as long as it exhibits a giant magnetoresistance effect. Further, the magnetoresistive element 1 is not limited to the one having the above laminated structure as long as it exhibits a giant magnetoresistive effect. The exchange bias layer 1a is X-Xn alone or an alloy containing the same (where X is one or more elements of Pt, Pd, Ir, Rh, Ru, and Os). ) Is preferred.

  The fixed layer 1b of the magnetoresistive effect element 1 shown in FIG. 7 is magnetized by the exchange bias layer 1a, and the magnetization direction is fixed (pinned) in a specific direction by the exchange bias layer 1a. The magnetization direction of the free layer 1d with respect to the magnetization direction of the fixed layer 1b is changed by an external magnetic field. A terminal layer 1 e is formed on both ends of the magnetoresistive element 1 by bonding. Then, a change in resistance value between the two terminal layers 1e is output as an output signal depending on the direction of the magnetization direction of the free layer 1d by the external magnetic field with respect to the fixed magnetization direction of the fixed layer 1b.

  The four magnetoresistive effect elements 1 shown in FIG. 7 are used, and the four magnetoresistive effect elements 1 are combined to form the bridge circuit shown in FIG. The magnetoresistive effect element in FIG. 6A is denoted by reference numerals GMR1, GMR2, GMR3, and GMR4, and one terminal layer formed at both ends of the magnetoresistive effect element is E1 and the other terminal layer. In the following description, E2 is attached.

  The four magnetoresistive effect elements GMR1, GMR2, GMR3, and GMR4 are used as a set of two magnetoresistive effect elements GMR1 and GMR2 and magnetoresistive effect elements GMR3 and GMR4 whose magnetization directions of the fixed layer 1b differ by 180 °. It is done. Further, the magnetization directions of the pinned layers 1d of the adjacent magnetoresistive elements GMR1 and GMR3 are 180 ° different, and the magnetization directions of the pinned layers 1d of the adjacent magnetoresistive elements GMR2 and GMR4 are 180 ° different.

  In FIG. 6A, the magnetization direction of the fixed layer of the magnetoresistive effect element GMR1 is set in the direction indicated by the right arrow, and the magnetization direction of the fixed layer of the magnetoresistive effect element GMR2 is 180 ° indicated by the left arrow. Different in the opposite direction. The magnetization direction of the fixed layer of the magnetoresistive effect element GMR3 is set in the direction indicated by the left arrow, and the magnetization direction of the fixed layer of the magnetoresistive effect element GMR4 is varied in the opposite direction of 180 ° indicated by the right arrow. Yes.

  Further, the magnetization direction of the fixed layer of one magnetoresistive effect element GMR1 of two adjacent magnetoresistive elements GMR1 and GMR3 is set in the direction indicated by the right arrow, and the fixed layer of the other magnetoresistive effect element GMR3 is set. The magnetization direction is varied in the opposite direction of 180 ° indicated by the left arrow. The magnetization direction of the fixed layer of one magnetoresistive effect element GMR2 of two adjacent magnetoresistive elements GMR2 and GMR4 is set in the direction indicated by the left arrow, and the magnetization of the fixed layer of the other magnetoresistive effect element GMR4 The direction is varied in the opposite direction of 180 ° indicated by the left arrow.

  In this case, since an external magnetic field does not act on the free layers of the four magnetoresistive elements GMR1, GMR2, GMR3, and GMR4, they are directed in an unspecified direction.

  Further, the terminal layer E1 of the other magnetoresistive effect element GMR2 is coupled to the terminal layer E2 of one magnetoresistive effect element GMR1 of the first set to connect the two magnetoresistive effect elements GMR1 and GMR2 in series. The terminal layer E1 of the other magnetoresistive effect element GMR4 is coupled to the terminal layer E2 of the second magnetoresistive effect element GMR3 to connect the two magnetoresistive effect elements GMR3 and GMR4 in series.

  The terminal layer E1 of the magnetoresistive effect element GMR1 and the terminal layer E1 of the magnetoresistive effect element GMR3 are connected, and the positive side of the power source Vcc is connected to the connection point V1. The terminal layer E2 of the magnetoresistive element GMR2 and the terminal layer E2 of the magnetoresistive element 4 are connected, and the ground side of the power source Vcc is connected to the connection point V2. Then, an input voltage is applied to the connection point V1 and the connection point V2.

  The terminal layer E2 of the magnetoresistive effect element GMR1 and the terminal layer E1 of the magnetoresistive effect element GMR2 are connected, and the connection point A + is used as an output unit that outputs a resistance value change signal of the magnetoresistive effect element. The terminal layer E2 of the magnetoresistive effect element GMR3 and the terminal layer E1 of the magnetoresistive effect element GMR4 are connected, and the connection point A− is used as an output unit that outputs a resistance value change signal of the magnetoresistive effect element. And the change signal of the resistance value of a magnetoresistive effect element is output from two connection point A + and connection point A-.

  When the direction of the magnetization direction of the free layer is uniformly changed by the external magnetic field with respect to the magnetization direction of the fixed layer of the four magnetoresistive effect elements GMR1, GMR2, GMR3, and GMR4 forming the bridge circuit, As a result of this change, resistance values change in the four magnetoresistive elements GMR1, GMR2, GMR3, and GMR4. The change in the resistance value shows the minimum value when the magnetization direction of the fixed layer and the magnetization direction of the free layer of the magnetoresistive effect element are the same direction, and the maximum value when it is antiparallel (opposite direction forming 180 °). Indicates. Accordingly, with the direction of the external magnetic field that magnetizes the free layer of the magnetoresistive element, the output signal (S1) having a sinusoidal waveform shown in FIG. 4C from the two connection points A + and A− serving as the output terminals of the bridge circuit. ', S2') is output. When the output voltage between the connection points A + and A− is taken, the output signal S1 of FIG. 4 (d) is obtained.

  Therefore, when the intermediate point of the resistance value change of the magnetoresistive effect element is taken as a reference point, the polarity of the resistance value change (the increasing direction is + and the decreasing direction is-) is the fixed layer of the magnetoresistive effect element. The magnetization directions of the magnetoresistive effect element GMR1 and the magnetoresistive effect element GMR4, and the magnetoresistive effect element GMR2 and the magnetoresistive effect element GMR3 have the same polarity, and the magnetization direction of the fixed layer of the magnetoresistive effect element is set to the same direction. The magnetoresistive effect element GMR1 and the magnetoresistive effect element GMR2, and the magnetoresistive effect element GMR3 and the magnetoresistive effect element GMR4, which have different directions in opposite directions (antiparallel) forming 180 °, have opposite polarities. Therefore, a Wheatstone bridge circuit is formed by the connection relationship between the four magnetoresistive elements GMR1, GMR2, GMR3, and GMR4 shown in FIG. 6A and the resistance value change of the magnetoresistive elements. By causing the resistance effect element to be magnetized by an external magnetic field, the resistance effect element functions as a magnetic sensor that performs a desired operation based on the change characteristic of the resistance value of the magnetoresistance effect element.

  The four magnetoresistive effect elements forming the bridge circuit according to the conventional example are formed on one substrate (wafer) as described in the section of the prior art, but 4 formed on the same substrate. The magnetization directions of the fixed layers of the magnetoresistive effect elements are different from each other by 90 ° (or 180 °) and are magnetized. For this reason, the magnitude of the magnetization magnetic field for fixing the magnetization direction of the fixed layer of the magnetoresistive effect element is about 200 (KA / m) at most.

  The present invention makes it possible to fix the magnetization by raising the magnitude of the magnetization magnetic field for fixing the magnetization direction of the fixed layer of the magnetoresistive effect element to 600 (KA / m). The basic configuration is that all the magnetoresistive elements formed on the same substrate are magnetized so that the magnetization directions of the fixed layers are aligned in the same direction, and chips including the magnetoresistive elements are individually ejected from the substrate. By selecting the magnetization direction of the pinned layer of the magnetoresistive effect element on the cut chip and assembling the magnetic sensor by combining a plurality of chips, the magnetoresistive effect element can be fixed with a sufficiently large magnetizing magnetic field. The layer is magnetized to output a large absolute value output signal from the magnetoresistive element. A specific aspect thereof will be described.

  In FIG. 1, a rectangular portion surrounded by a one-dot chain line drawn vertically and horizontally on a substrate 2 shows a plurality of chips 3 cut out from one substrate 2. In the example of FIG. An example is shown in which two magnetoresistive elements 1, 1 are formed on a chip 3.

  The same substrate 2 is formed by aligning a plurality of magnetoresistive elements 1 vertically and horizontally so that two magnetoresistive elements 1 are included in each chip 3 surrounded by an alternate long and short dashed line on one substrate 2. Form on top. When a plurality of magnetoresistive elements 1 are formed on the same substrate 2, an external magnetic field is applied in a state where the temperature is equal to or higher than the blocking temperature, and the fixed layers of these magnetoresistive elements 1 are oriented in the same direction. Align. In the example shown in FIG. 1, the directions of the fixed layers of the plurality of magnetoresistance effect elements 1 are aligned upward (vertical direction in the figure).

  Furthermore, the connection pads P1, P2, P3, and P4 corresponding to the connection points A +, V1, A−, and V2 of the bridge circuit shown in FIG. 6A are formed on the two sides that form the corners of the rectangular chip 3. Are formed at regular intervals along one side (3a). Further, connection pads P1 ', P2', and P3 'that are paired with connection pads P1, P2, P3, and P4 corresponding to connection points A +, V1, A-, and V2 of the bridge circuit shown in FIG. , P4 ', and these connection pads P1', P2 ', P3', P4 'are formed at regular intervals along the other side (3b) of the two sides forming the corners of the rectangular chip 3 Then, these are arranged on the same substrate 2 by being aligned vertically and horizontally.

  In this case, the pair of connection pads P1, P2, P3, P4 and the connection pads P1 ′, P2 ′, P3 ′, P4 ′ form the corners of the chip 3 as shown in an enlarged view in FIG. They can be formed at symmetrical positions on the two sides 3a and 3b. The connecting pads P 1, P 2, P 3 and P 4 and the connecting pads P 1 ′, P 2 ′, P 3 ′ and P 4 ′ that form a pair are the corners of a plurality of chips 3 that are partitioned on one substrate 2. Each of the chips 3 is formed along a plurality of chips 3 on which two magnetoresistive effect elements 1 are formed.

  As shown in FIGS. 1 and 2, the terminal E1 of one magnetoresistive effect element 1 formed on the chip 3 is connected to the connection pad P1 and the connection pad P1 ′ by a circuit pattern, and the terminal E2 is connected. The circuit pads are connected to the connection pads P2 and the connection pads P2 ′, respectively.

  Further, the terminal E1 of the other magnetoresistive element 1 formed on the chip 3 is connected to the connection pad P3 and the connection pad P3 ′ by a circuit pattern, and the terminal E2 is connected to the connection pad P4 and the connection pad P4. 'Is connected to each by a circuit pattern.

  Although FIG. 1 shows that 16 chips 3 on which two magnetoresistive elements 1 are formed are formed on the substrate 2, the number of formed chips is not limited to 16. Further, although the chips 3 are arranged uniformly in the vertical and horizontal directions, they may be arranged non-uniformly in the vertical and horizontal directions, or they may be formed in a horizontal and vertical row, and are not limited to this arrangement shape.

  Further, when forming the two magnetoresistive effect elements 1, markings M indicating the directions of the fixed layers of the magnetoresistive effect elements 1 are respectively formed on the chip 3. In FIG. 1, the marking M is formed in the vicinity of the upper left corner of the chip 3 where the horizontal extension line of the connection pad P1 and the vertical extension line of the connection pad P1 ′ intersect.

  Thereafter, a plurality of chips 3 each including two magnetoresistive effect elements 1 and eight connection pads P1, P2, P3, P4, P1 ′, P2 ′, P3 ′, and P4 ′ are shown in FIG. Cut out from the substrate 2 individually along vertical and horizontal alternate long and short dash lines. The individually cut chips 3 are enlarged and shown in FIG.

  Next, as shown in FIG. 4A, the direction of the magnetization direction of the fixed layer of the magnetoresistive effect element 1 on the cut chip 3 is selected, and the four chips 3 are combined. In FIG. 4A, four chips 4 are combined such that the magnetization direction of the fixed layer of the magnetoresistive effect element 1 is different by 90 ° in the same rotation direction. In FIG. 4 (a), there is shown a space between the chips 3. However, in order to assemble the chips 3, the magnetoresistive effect is obtained by abutting the chips 3 together without any gaps. The elements 1 are adjacent to each other. With this combination, the magnetic sensitivity of the four magnetoresistive elements 1 with respect to the external magnetic field can be made uniform, and an accurate output signal can be output.

  In this embodiment, since the magnetization directions of the fixed layers of the plurality of magnetoresistive effect elements 1 formed on the same substrate 2 are magnetized in the same direction, the magnetizing magnetic field applied to the adjacent magnetoresistive effect elements Can affect each other, and the magnitude of the magnetic field for magnetizing the fixed layer of the magnetoresistive effect element 1 can be increased to 600 (KA / m). The fixed layer of the resistance effect element can be fixed by magnetization. Therefore, by increasing the magnetic sensitivity of the magnetoresistive effect element, the absolute value of the output signal can be increased, and accurate magnetic field detection can be performed. Also, the output accuracy can be increased. Further, the outer shape of the chip 3 is formed in a rectangular shape, and the direction of the magnetoresistive effect element 1 and connection pads P1, P2, P3, P4, P1 ′, P2 ′, P3 ′, P4 ′ are formed on the chip 3. Are aligned in the vertical and horizontal directions on the same substrate 2, so that the magnetization direction of the fixed layer of the magnetoresistive effect element 1 differs by 90 ° in the same rotational direction by four chips. Even if 3 are arranged, chips can be arranged without gaps, and the mounting accuracy can be improved.

  In order to clarify the relationship between the magnetoresistive effect element shown in FIG. 4A and the magnetoresistive effect element of the bridge circuit shown in FIG. 6A, FIG. 4A shows the first of FIG. Reference numerals GMR1, GMR2, GMR3, and GMR4 are attached to the magnetoresistive effect element that outputs the phase output signal S1, and the magnetoresistive effect element that outputs the second phase output signal S2 in FIG. ', GMR2', GMR3 ', GMR4' will be described with reference numerals. The signals S1 and S2 in FIG. 4D are out of phase by 90 ° because the magnetization directions of the four magnetoresistive elements are 90 °.

  In FIG. 4A, the magnetization direction H3 of the fixed layers of the magnetoresistive effect elements GMR1 and GMR4 is set upward, and the magnetization direction H4 of the fixed layer of the magnetoresistive effect elements GMR2 and GMR3 is 180 indicated by a down arrow. Different downward direction (anti-parallel). In addition to the four magnetoresistive elements GMR1, GMR2, GMR3, and GMR4, four magnetoresistive elements GMR1 ′, GMR2 ′, and GMR3 ′ are provided to output two-phase output signals S1 and S2. , GMR4 '. In this case, the magnetization direction H5 of the fixed layer of the magnetoresistive elements GMR1 'and GMR4' is set to the left lateral direction, and the magnetization direction H6 of the fixed layer of the magnetoresistive elements GMR2 'and GMR3' is indicated by a right arrow. Different in the right lateral direction (anti-parallel) at 180 °.

  First, the configuration of the bridge circuit for outputting the first-phase output signal (sine waveform) S1 shown in FIG. The connection pad P1 of the magnetoresistive effect element GMR1 and the connection pad P3 of the magnetoresistive effect element GMR2 are connected by wire bonding, and the two magnetoresistive effect elements GMR1 and GMR2 are connected in series. The connection pad P2 of the magnetoresistive effect element GMR3 and the connection pad P3 of the magnetoresistive effect element GMR4 are connected by wire bonding, and the two magnetoresistive effect elements GMR3 and GMR4 are connected in series.

  Next, the connection pad P2 of the magnetoresistive effect element GMR1 and the connection pad P2 of the magnetoresistive effect element GMR3 are connected by wire bonding, and the positive side of the power supply Vcc is connected to the connection point (V1). The connection pad P4 of the magnetoresistive effect element GMR2 and the connection pad P4 of the magnetoresistive effect element GMR4 are connected by wire bonding, and the ground side of the power supply Vcc is connected to the connection point (V2). The two connection points (V1, V2) are used as terminals for applying the output voltage. Then, the circuit shown in FIG. 6 is configured.

  Further, the connection pad P1 'of the magnetoresistive effect element GMR1 and the connection pad P3' of the magnetoresistive effect element GMR2 are connected by wire bonding, and the connection point (A +) is used to change the resistance value of the magnetoresistive effect element. An output unit for outputting. The connection pad P1 of the magnetoresistive effect element GMR3 and the connection pad P3 'of the magnetoresistive effect element GMR4 are connected by wire bonding, and the connection point A- is used to output a change in the resistance value of the magnetoresistive effect element. The output section. The two connection points (A +, A−) are used as terminals for outputting a change signal of the resistance value of the magnetoresistive element.

  Next, the configuration of the bridge circuit that outputs the second-phase output signal (sine waveform) S2 shown in FIG. The connection pad P1 of the magnetoresistive effect element GMR1 ′ and the connection pad P3 of the magnetoresistive effect element GMR2 ′ are connected by wire bonding, and the two magnetoresistive effect elements GMR1 ′ and GMR2 ′ are connected in series. The connection pad P2 of the magnetoresistive effect element GMR3 ′ and the connection pad P3 of the magnetoresistive effect element GMR4 ′ are connected by wire bonding, and the two magnetoresistive effect elements GMR3 ′ and GMR4 ′ are connected in series.

  Next, the connection pad P2 of the magnetoresistive effect element GMR1 ′ and the connection pad P2 of the magnetoresistive effect element GMR3 ′ are connected by wire bonding, and the positive side of the power source Vcc is connected to the connection point (V1). The connection pad P4 of the magnetoresistive effect element GMR2 'and the connection pad P4 of the magnetoresistive effect element GMR4' are connected by wire bonding, and the ground side of the power supply Vcc is connected to the connection point (V2). The two connection points (V1, V2) are used as terminals for applying the output voltage. Then, a circuit similar to the circuit shown in FIG. 6 is configured.

  Further, the connection pad P1 ′ of the magnetoresistive effect element GMR1 ′ and the connection pad P3 ′ of the magnetoresistive effect element GMR2 ′ are connected by wire bonding, and the connection point (A +) is set to the resistance value of the magnetoresistive effect element. An output unit for outputting changes. The connection pad P1 of the magnetoresistive effect element GMR3 'and the connection pad P3' of the magnetoresistive effect element GMR4 'are connected by wire bonding, and the connection point (A-) is used to change the resistance value of the magnetoresistive effect element. An output unit for outputting. The two connection points (A +, A−) are used as terminals for outputting a change signal of the resistance value of the magnetoresistive element. Since the plurality of connection pads described above are formed at symmetrical positions on the two sides forming the corners of the rectangular chip, when these are wire bonded, the position data of the connection pads is used as the existing wire bonding. The connection work can be performed mechanically by inputting to the apparatus, and the chip can be easily assembled.

  Four magnetoresistive elements GMR1, GMR2, GMR3, and GMR4 forming a first bridge circuit that outputs the first-phase output signal S1 of FIG. 4D, and the second-phase output of FIG. 4D. The four magnetoresistive elements GMR1 ′, GMR2 ′, GMR3 ′, and GMR4 ′ forming the second bridge circuit that outputs the signal S2 are arranged so that their magnetization directions are different from each other by 90 ° in the same rotation direction. The

  When an external magnetic field acts on the free layer of these magnetoresistive effect elements and the magnetization direction of the free layer rotates with respect to the fixed magnetization direction of the fixed layer according to the direction of the external magnetic field, the magnetization direction of the free layer rotates. The resistance value changes in accordance with. The change in resistance value shows a minimum value when the magnetization direction of the fixed layer of the magnetoresistive effect element and the magnetization direction of the free layer are the same direction, and shows a maximum value when it is antiparallel (opposite direction forming 180 °). The two-phase output signals S1 and S2 having a sine curve (sinusoidal waveform) shown in FIG. 4C and shifted in phase by 90 ° depending on the direction of the external magnetic field are respectively the first bridge circuit and the second bridge circuit. Are output from the connection points A + and A−.

  Therefore, when the intermediate point of the resistance value change of the magnetoresistive effect element is used as a reference point, the polarity of the resistance value change (the increasing direction is + and the decreasing direction is-) is the magnetization direction of the fixed layer. Magnetoresistive element GMR1 and magnetoresistive element GMR4, magnetoresistive element GMR1 ′, magnetoresistive element GMR4 ′, magnetoresistive element GMR2, magnetoresistive element GMR3, magnetoresistive element GMR2 ′ set in the same direction And the magnetoresistive effect element GMR3 ′ have the same polarity. The magnetoresistive effect element GMR1 and the magnetoresistive effect element GMR2, the magnetoresistive effect element GMR1 ′, the magnetoresistive effect element GMR2 ′, and the magnetoresistive effect element GMR3 are different from each other in the direction of magnetization of the fixed layer being 180 °. The magnetoresistive effect element GMR4, the magnetoresistive effect element GMR3 ', and the magnetoresistive effect element GMR4' have opposite polarities.

  Therefore, the magnetoresistive effect elements GMR1, GMR2, GMR3, GMR4, GMR1 ′, GMR2 ′, GMR3 ′, GMR4 ′ shown in FIG. Two Wheatstone bridge circuits are formed and function as a magnetic sensor by making the magnetoresistive effect element sensitive to magnetism by an external magnetic field.

  Also, as shown in FIG. 4B, four chips 3 are mounted on a lead frame (not shown), and the connection pads common to the magnetoresistive effect elements formed on the four chips 3 are connected to the lead frame. The 16 terminals T formed in the above are connected by wire bonding. Thereafter, the four chips 3 can be hermetically sealed with the sealing resin 4 to form an IC chip 87. In this case, for sealing at a position corresponding to the terminal T serving as the starting point of the magnetoresistive effect element on the chip 3 combined so that the magnetization directions of the fixed layers of the magnetoresistive effect element are different by 90 ° in the same rotation direction. It is desirable to add a marking M ′ to the resin 4.

  In FIG. 4, four chips 3 having two magnetoresistive elements are combined, but N / 2 having two magnetoresistive elements (N = 2, 4, 6, 8 to 2n). By disposing the chips 3 on the combination circumference with a predetermined angle shift, an output signal (sine waveform) of N / 2 phase (N = 2, 4, 6, 8 to 2n) can be output. .

  9 and 10 show examples in which a variable resistor is configured using the magnetic sensor described above. The potentiometer M1 shown in FIG. 9 includes a rotating shaft 80, a bearing member 81 that supports the rotating shaft 80 so as to be rotatable about the shaft, and a cap-like shape that is attached to the back surface side of the bearing member 81 and attached to the bearing member 81. Cover member 82, magnetic code member 83 integrally provided with rotating shaft 80 on the back side of bearing member 81 covered with cover member 82, circuit components such as IC chip 87 described above, and signal to the outside And a holder member 85 for attaching the attachment substrate 86 to the bearing member 81.

  The bearing member 81 is formed, for example, by cutting brass, and the cover member 82 is formed, for example, from a member obtained by drawing a metal plate. The rotary shaft 80 is a rod-shaped member made of a non-magnetic material such as resin or nonmagnetic stainless steel, and one end portion side of the rotary shaft 80 penetrates the bearing member 81 and protrudes to the back surface side, and a disc shape is formed at one end portion thereof. The magnetic cord member 83 is attached to the rotary shaft 80 at a right angle. The magnetic cord member 83 has one neutral point 84 passing through the central magnetism O on one surface as a boundary, and one side (left side in FIG. 10) is an S pole and the other side (right side in FIG. 10) is an N pole. It is formed from a magnetized magnet plate.

  Here, the rotating shaft 80 may be formed of soft magnetic iron, or formed of a ferromagnetic material when the magnetic code member 83 and the IC chip 87 are sufficiently separated from each other. But you can. The IC chip 87 and the magnetic code member 83 are provided in parallel with a gap. The distance (gap) between the magnetic code member 83 and the substrate 86 is set as a distance for use in a region where the giant magnetoresistive elements 26 and 27 are saturated by the magnetic field generated by the magnetic code member 83, Usually, it is about several millimeters to several tens of millimeters. Further, the rotation center O of the rotary shaft 80 is arranged so as to coincide with the centers of the four chips indicated by α in FIG. 4, the IC chip 87 is sufficiently small compared to the size of the magnet, and the magnet has two poles. Therefore, as shown in FIG. 10, a parallel magnetic field M directed in one direction is applied to the IC chip 87 and changes so as to rotate in the direction of the magnetic field in accordance with the rotation of the rotary shaft 80, and operates as described above. As shown in FIG. 4D, a sine wave whose phase is shifted by 90 ° is output.

  4 and 6A, a bridge circuit is formed using four magnetoresistive elements, but voltage is divided using two magnetoresistive elements GMR1 and GMR2 as shown in FIG. 6B. A circuit may be formed. In the voltage dividing circuit shown in FIG. 6B, two magnetoresistive elements GMR1 and GMR2 are connected in series, and the positive side of the power supply Vcc is connected to the terminal E1 of the magnetoresistive element GMR1 (connection point V1). The ground side of the power source Vcc is connected to the terminal E2 of the magnetoresistive effect element GMR2 (connection point V2). The terminal E2 of the magnetoresistive effect element GMR1 and the terminal E1 of the magnetoresistive effect element GMR2 are connected, and the connection point A is used as an output terminal. In this case, the magnetization directions of the fixed layers of the two magnetoresistive elements GMR1 and GMR2 are made different in opposite directions (antiparallel) of 180 °.

  A voltage is applied to the connection points V1 and V2 of the two magnetoresistive elements GMR1 and GMR2 connected in series, and from the connection point A, the resistance values of the two magnetoresistive elements GMR1 and GMR2 are changed. A fluctuating divided voltage is output, and the magnetic sensitivity due to the external magnetic field of the magnetoresistive element is detected based on the change in the output value.

  Each magnetoresistive effect element GMR1, GMR2 is formed on the chip 3 in pairs with connection pads P1, P2, P1 ', P2' connected to its terminals, as shown in FIGS. Is done.

  A case where one magnetoresistive element used in the example of FIGS. 5 and 6B is formed in one chip will be described. As shown in FIG. 3, in one chip 3, one magnetoresistive effect element 1 and connection pads P1, P2, and P1 forming a pair connected to terminals E1 and E2 of the magnetoresistive effect element 1 are provided. 'And P2' are formed in pairs. A plurality of chips 3 are formed on the substrate 2 shown in FIG. In the case of the chip 3 shown in FIG. 3, the chip is in a state in which the magnetoresistive effect element 1 having the connection pads P3, P4, P3 ′, and P4 ′ shown in FIG. 1 is removed. When a plurality of magnetoresistive elements 1 are formed on the same substrate 2 by being aligned vertically and horizontally, an external magnetic field is applied in a state where the temperature is equal to or higher than the blocking temperature, and the magnetoresistive elements 1 are fixed by cooling. Align layers in the same direction.

  Further, as shown in an enlarged view in FIG. 3, the connection pads P1 and P2 corresponding to the connection points V1 (V2) and A of the voltage dividing circuit in FIG. 6B are formed at the corners of the rectangular chip 3. Are formed at regular intervals along one of the two sides 3a. Corresponding to the connection points V1 (V2) and A of the voltage dividing circuit of FIG. 6B, connection pads P1 'and P2' paired with the connection pads P1 and P2 are provided, and these connection pads P1 ' , P2 ′ are formed at regular intervals along the other side 3b of the two sides that form the corners of the rectangular chip 3. The connection pads P1 and P2 and the connection pads P1 ′ and P2 ′ forming a pair are aligned along the two sides 3a and 3b forming the corners of the chip 3 partitioned on one substrate 2. It is provided at the peripheral edge of one magnetoresistive element 1 formed on the chip 3.

  The terminal E1 of the magnetoresistive effect element 1 is connected to the connection pad P1 and the connection pad P1 ′ by a circuit pattern, and the terminal E2 is connected to the connection pad P2 and the connection pad P2 ′ by a circuit pattern. The

  When the magnetoresistive effect element 1 is formed, markings M indicating the direction of the magnetoresistive effect element 1 are formed on the chip 3 respectively. In FIG. 3, the marking M is formed in the vicinity of the upper left corner of the chip 3 where the horizontal extension line of the connection pad P1 and the vertical extension line of the connection pad P1 ′ intersect.

  After the completion of the magnetization, a plurality of chips 3 each composed of one magnetoresistive effect element 1 and four connection pads P1, P2, P1 ′, P2 ′ are the same as shown in FIG. Cut out from the substrate 2 individually along vertical and horizontal alternate long and short dash lines. The individually cut chips 3 are enlarged and shown in FIG.

  Next, as shown in FIG. 5A, the direction of the magnetization direction of the fixed layer of the magnetoresistive effect element 1 on the cut chip 3 is selected, and the two chips 3 are combined. In FIG. 5A, the two chips 3 are combined by changing the magnetization directions H8 and H9 of the magnetoresistive effect element 1 in opposite directions (antiparallel) of 180 °. Although FIG. 5A shows that there is a space between the chips 3, in order to assemble the chips 3, the magnetoresistive effect element 1 is obtained by abutting the chips 3 with each other without a gap. Are adjacent to each other. This combination makes it possible to equalize the magnetic sensitivity of the two magnetoresistive elements 1 to the external magnetic field and output an accurate output signal.

  In this embodiment, one magnetoresistive element 1 is formed on one chip 3, but when forming on the substrate 2, the magnetization directions of the fixed layers of the plurality of magnetoresistive elements 1 are aligned in the same direction. Since it is magnetized and fixed (pinned), there is no problem even if magnetized magnetic fields applied to adjacent magnetoresistive elements influence each other, and the magnetic field that magnetizes the fixed layer of the magnetoresistive element 1 is, for example, It can be increased to 600 (KA / m), and the pinned layer of the magnetoresistive effect element can be fixed by magnetization with the increased magnetization magnetic field. Therefore, by increasing the magnetic sensitivity of the magnetoresistive effect element, the absolute value of the output signal can be increased, and accurate magnetic field detection can be performed. Also, the output accuracy can be increased.

  In order to clarify the relationship between the magnetoresistive effect element shown in FIG. 5A and the magnetoresistive effect element of the bridge circuit shown in FIG. 6B, in FIG. A description will be given with reference to GMR2. In this case, the magnetization direction H8 of the fixed layer of the magnetoresistive effect element GMR1 is set downward, and the magnetization direction H9 of the fixed layer of the magnetoresistive effect element GMR2 is 180 degrees upward (antiparallel) indicated by the up arrow. ). A voltage dividing circuit shown in FIG. 5A formed by using two chips 3 on which one magnetoresistive effect element is formed has the circuit configuration shown in FIG.

  As shown in FIG. 3, even when one magnetoresistive element is formed on one chip 3, an external magnetic field acts on the free layer with respect to the magnetization direction of the fixed layer of the magnetoresistive element. Thus, the resistance value changes according to the rotation of the magnetization of the free layer. The change in the resistance value shows the minimum value when the magnetization direction of the fixed layer and the magnetization direction of the free layer of the magnetoresistive effect element are the same direction, and the maximum value when it is antiparallel (opposite direction forming 180 °). Indicates.

  Further, as shown in FIG. 5B, the two chips 3 are mounted on a lead frame (not shown), and the connection pads common to the magnetoresistive effect elements of the two chips 3 are formed on the lead frame. The IC chip 87 can be configured by connecting to the eight terminals T and hermetically sealing the two chips 3 with the sealing resin 4. In this case, it is desirable to place a marking M ′ at a position corresponding to the terminal T that is the starting point of the magnetoresistive effect element that is varied in the direction of 180 °.

  FIGS. 8A and 8B are diagrams showing an example in which a magnetic switch that performs a switch operation (contact ON / OFF) in a non-contact manner using the magnetic sensor of the present invention is shown. In response to the switching operation (ON, OFF) of this magnetic switch, the magnetic resistance of the first magnet 5 and the second magnet 6 having opposite magnetic field directions and different magnitudes is used as an external magnetic field. By selectively acting on the element 1, a switching signal for switching operation is output from the magnetoresistive effect element 1. More specifically, as shown in FIGS. 8A and 8B, the magnetic switch holder 7 has a U-shape in which arms 9 and 10 that are paired at both ends of the base 8 are provided in parallel to face each other. It is formed in a mold shape. A pair of arms 9 has a magnetoresistive element 1 and a second permanent magnet (hereinafter referred to as a second magnet) 6, and the other arm 10 has a first permanent magnet (hereinafter referred to as a first magnet). 4) (referred to as magnets).

  In this case, as the chip 3, as shown in FIG. 3, a chip in which one magnetoresistive element 1 is formed on one chip 3 is used. Two chips 3 are used, and the two magnetoresistive effect elements 1 are incorporated as magnetoresistive effect elements GMR1 and GMR2 of the bridge circuit shown in FIG. 6A, and the magnetoresistance of the bridge circuit shown in FIG. The effect elements GMR3 and GMR4 are replaced with fixed resistors. The two chips 3 have opposite directions (antiparallel) in which the magnetization directions of the two magnetoresistive elements 1 form 180 ° as in the magnetoresistive elements GMR1 and GMR2 of the bridge circuit shown in FIG. To be different. The chip 3 is mounted on the substrate 12 and attached to the inner surface of one arm 9 via the substrate 12. In FIGS. 8A and 8B, the chip 3 is not shown, and the magnetoresistive effect element GMR1 and GMR2 of the bridge circuit shown in FIG. Indicated as 1.

  The second magnet 6 is attached to one arm 9 at a magnetic field action position that magnetizes the free layer 1d (see FIG. 7) of the magnetoresistive element 1 with a magnetic field. Here, the magnetic field action position is such that the magnetic force lines 6a of the second magnet 6 act on the free layer 1d of the magnetoresistive effect element 1, and the free layer of the magnetoresistive effect element 1 by the magnetic field of the second magnet 6 (external magnetic field). 1d is set to a magnetizable position.

  The first magnet 5 is disposed at a position where the magnetic layer (external magnetic field) acts on the free layer 1d (see FIG. 7) of the magnetoresistive effect element 1 and the free layer 1d can be magnetized (magnetic field acting position). In addition, the magnetic field lines (direction of magnetic field) 5a are attached to the other arm 10 so as to be different from the magnetic field lines (direction of magnetic field) 6a of the second magnet 6 in the opposite direction (antiparallel) of 180 °. As the first magnet 5, a magnet having a magnetic force several hundred gauss larger than the magnetic force of the second magnet 6 is used.

  Furthermore, it has the magnetic field shielding member 11 which consists of a ferromagnetic material from which the relative position with respect to the 1st, 2nd magnets 5 and 6 changes. The magnetic field shielding member 11 has a first position in which both the magnetic fields of the first and second magnets 5 and 6 act on the magnetoresistive effect element 1 so that the magnetization direction of the free layer 1d is the first direction. A second position in which one of the magnetic fields of the first and second magnets 5 and 6 acts on the magnetoresistive element 1 so that the magnetization direction of the free layer 1d is a second direction opposite to the first direction; Move to. As shown in FIG. 8A, the first position is set to a position where the magnetic shielding member 11 is retracted from between the first magnet 5 and the magnetoresistive element 1. On the other hand, as shown in FIG. 8B, the second position is set to a position where the magnetic field shielding member 11 enters between the first magnet 5 and the magnetoresistive element 1.

  When the magnetic shielding member 11 is moved to the second position by the driving means (not shown), the magnetic shielding member 11 moved to the second position as shown in FIG. Is separated from the free layer 1d of the magnetoresistive effect element 1 to shield the magnetic field of the first magnet 5, and only the magnetic field of the second magnet 6 acts on the magnetoresistive effect element 1 as an external magnetic field. Therefore, only the magnetic field of the second magnet 6 having a smaller magnetic force than the first magnet 5 acts on the magnetoresistive element 1 as an external magnetic field in the free layer 1 d of the magnetoresistive element 1.

  On the other hand, when the magnetic field shielding member 11 moves to the first position as shown in FIG. 8A, both the magnetic fields of the first and second magnets 5 and 6 are external magnetic fields in the magnetoresistive effect element 1. Works. In this case, the magnetic force of the first magnet 5 is greater than that of the second magnet 6, and the magnetization direction of the first magnet 5 and the second magnet 6 with respect to the free layer 1 d of the magnetoresistive effect element 1 is 180 °. Different in the opposite direction.

  Accordingly, the magnetic force generated by the second magnet 6 is canceled out by the magnetic force generated by the first magnet 5, and the magnetic field of the first magnet 5 acts on the free layer 1 d of the magnetoresistive effect element 1. The magnetization direction of the layer 1d is reversed and switched to the opposite direction that forms 180 ° with the magnetization direction of the second magnet 6.

  Based on the reversal switching of the magnetization direction of the free layer 1 d of the magnetoresistive effect element 1 by the first magnet 5 and the second magnet 6, the resistance value of the magnetoresistive effect element 1 changes. Furthermore, since the magnetization direction of the free layer 1d of the magnetoresistive effect element 1 by the two magnets 5 and 6 is different from the magnetization direction of the fixed layer of the magnetoresistive effect element at 180 °, its resistance value Changes are made instantaneously.

  In the case of switching off, as shown in FIG. 8A, the magnetic field shielding member 11 retreats from between the magnetoresistive effect element 1 and the first magnet 5, so that the magnetic field from the first magnet 5 is magnetoresistive. Acts on the element 1. In this case, since the direction of the magnetic force line 5a of the first magnet 5 and the magnetization direction of the free layer of one of the two magnetoresistive effect elements 1 are the same, the magnetization direction is 180 °. The resistance value of the other magnetoresistive effect element 1 made different in the opposite direction is increased.

  When the switch is turned on, the magnetic field shielding member 11 enters between the magnetoresistive effect element 1 and the first magnet 5 as shown in FIG. 8B, so that the first magnet 5 moves to the magnetoresistive effect element 1. The magnetic field of only the second magnet 6 acts on the magnetoresistive effect element 1. In this case, a change in the resistance value of the magnetoresistive effect element 1 in which the direction of the magnetic force lines 6a of the second magnet 6 and the direction of the magnetization direction are opposite to each other becomes large.

  A change in the resistance value of the magnetoresistive effect element 1 described above is output from the bridge circuit, and a switch operation switching signal is output.

  According to this magnetic switch, in response to the switching operation of the switch, the magnetic field of the first magnet 5 and the second magnet 6 having opposite magnetic fields and different magnitudes is applied to the magnetoresistive effect element 1 as an external magnetic field. Acting selectively, the switch signal of the switch operation is output from the magnetoresistive effect element 1, and the switch is switched based on the output signal. The direction of the magnetic field (the magnetization direction of the magnetoresistive effect element) can be changed to the opposite direction of 180 °. Therefore, even if the magnetic field strength gradually changes, the resistance value of the magnetoresistive element can be changed abruptly, and the switch operation can be quickly performed based on the abrupt change in resistance value. Can do.

  In the above description, the magnetic switch is configured using a magnetic sensor, but the present invention is not limited to this, and a free layer whose magnetization direction is changed by an external magnetic field that detects a detected member having a magnetic field shielding action is provided. It can also be configured as an object detection sensor using the magnetoresistive effect element. In this embodiment, in response to the movement of the member to be detected, the magnetic field of the first magnet and the second magnet having different magnetic field directions and different magnitudes is selectively applied to the magnetoresistive effect element as an external magnetic field. By doing so, the detection signal of the member to be detected can be output from the magnetoresistive effect element.

  This detection sensor uses a magnetic field shielding member 11 of the magnetic switch shown in FIG. 8 as a detected member having a magnetic field shielding action, and is different from the magnetic switch in that the detected member (11) is detected. ing. Other configurations are the same as those of the magnetic switch shown in FIG.

  The detected member (11) moves so that the relative position with respect to the first and second magnets 5 and 6 changes. By changing the relative position of the detected member (11) with respect to the first and second magnets 5 and 6, both the magnetic fields (external magnetic fields) of the first and second magnets 5 and 6 are applied to the magnetoresistive effect element 1. The first member to be actuated and the second state in which one of the magnetic fields (external magnetic fields) of the first and second magnets 5 and 6 is caused to act on the magnetoresistive effect element 1 are generated, and the member to be detected (11). Is detected.

  The first state is set to a state in which the magnetic field shielding member 11 is withdrawn from between the first magnet 5 and the magnetoresistive effect element 1 (see FIG. 8A). On the other hand, a 2nd state is set to the state which the magnetic field shielding member 11 approached between the 1st magnet 5 and the magnetoresistive effect element 1 (refer FIG.8 (b)). And the to-be-detected member 11 in a 2nd state shields the magnetic field of the 1st magnet 5 with a larger magnetic force than the 2nd magnet 6, and only the magnetic field of the 2nd magnet 6 becomes a magnetoresistive effect as an external magnetic field. Acts on the element 1.

  According to this object detection sensor, in response to the movement of the member to be detected (11), the magnetic fields of the first magnet 5 and the second magnet 6 having opposite directions and different magnitudes are used as external magnetic fields. Selectively acting on the resistive effect element 1, outputting a detection signal of the detected member (11) from the magnetoresistive effect element 5, and detecting the detected member (11) based on the output signal; The direction of the magnetic field with respect to the magnetoresistive effect element 1 (the magnetization direction of the magnetoresistive effect element) can be changed to the opposite direction of 180 ° by the movement of the member to be detected (11).

  FIG. 11 shows an example in which a variable resistor is configured using the magnetic sensor described above. The variable resistor includes a rotating shaft 80, a bearing member 81 that supports the rotating shaft 80 so as to be rotatable about the axis, and a cover member 82 that is attached to the bearing member 81 and attached to the back surface side of the bearing member 81. The shield plate 90 and magnetic code members 13a and 13b provided integrally with the rotary shaft 80 on the back side of the bearing member 81, circuit components such as the IC chip 87 shown in FIG. And a mounting board 86 mounted on the cover member 82.

  The rotary shaft 80 is a rod-shaped member made of a non-magnetic material such as resin or nonmagnetic stainless steel, and one end portion side of the rotary shaft 80 penetrates the bearing member 81 and protrudes to the back surface side. A dish-shaped shielding member 90 formed of a steel plate or the like that shields is integrally provided. A pair of magnetic cord members 13a and 13b made of two-pole permanent magnets of N and S poles are attached to the inner surface of the shielding member 90 at positions facing each other across the rotation axis O, and the magnetic cord members 13a and 13b. Thus, a magnetic field sufficient to saturate the GMR element (giant magnetoresistive element) is applied.

  Further, the IC chip 87 is mounted on the mounting substrate 86 so as to be positioned on a line connecting the intermediate positions of the magnetic cord members 13a and 13b in the axial direction, and the rotation center O of the rotating shaft 80 is four chips indicated by α in FIG. It arrange | positions so that it may correspond with the center of. The IC chip 87 is sufficiently smaller than the magnet length, and a parallel magnetic field M directed in one direction is applied to the IC chip 87 as shown in FIG. It changes so as to rotate and operates in the same manner as described above to output a sine wave whose phase is shifted by 90 ° as shown in FIG.

  In the variable resistor shown in FIGS. 9 and 10, a slightly curved portion of the magnetic lines of force generated by the magnetic code member 83 is added to the IC chip 87. In this embodiment, the magnetic code members 13a and 13b are opposed to each other. Since the IC chip 87 is provided on the surface where both are arranged, and the GMR element (giant resistance effect element) is arranged in a range shorter than the length of the magnet, the GMR element in the IC chip 87 is arranged. Is applied with a parallel magnetic field that is closer to a straight line, and therefore, an output that is closer to a sine wave can be achieved.

  8, 9, 10, and 11, the case where the magnetic sensor of the present invention is applied to a magnetic switch, an object detection sensor, or a variable resistor has been described. The application range of the magnetic sensor of the present invention is illustrated in FIG. 8. And it is not limited to the thing of FIG. 9, FIG. 10, FIG.

In this invention, it is a top view which shows the case where a several magnetoresistive effect element is formed on a board | substrate. It is a top view which shows the case where two magnetoresistive effect elements are formed in one chip | tip. It is a top view which shows the case where one magnetoresistive effect element is formed in one chip | tip. (A) is a plan view showing a case where a bridge circuit is formed by combining four chips, (b) is a plan view showing a case where an IC chip is formed, and (c) and (d) are two-phase circuits. It is a characteristic view which shows an output signal. (A) is a plan view showing a case where a voltage dividing circuit is formed by combining two chips, (b) is a plan view showing a case where an IC chip is formed, and (c) is a one-phase output signal. FIG. (A) is a bridge circuit diagram, (b) is a voltage dividing circuit diagram. It is sectional drawing which shows a magnetoresistive effect element. (A), (b) is the figure which comprised the magnetic switch using the magnetic sensor of this invention. It is sectional drawing which comprised the variable resistor using the magnetic sensor of this invention. It is sectional drawing which shows the principal part of the variable resistor shown in FIG. It is a figure which shows the other example of the variable resistor of this invention, (a) is principal part sectional drawing, (b) is sectional drawing.

Explanation of symbols

1 magnetoresistive effect element (GMR1, GMR2, GMR3, GMR4, GMR1 ′
GMR2 'GMR3' GMR4 ')
2 Substrate 3 Chip 4 Sealing resin 5 First magnet 6 Second magnet 11 Magnetic field shielding member (detected member)
13 Rotating magnetic field 13a Magnetic code member 13b Magnetic code member M Marking

Claims (10)

On the chip on which a plurality of connection pads connected to the magnetoresistive effect element and the terminals of the magnetoresistive effect element are formed,
A magnetic sensor characterized by displaying markings for identifying the magnetization direction of the fixed layer of the magnetoresistive element. The magnetic sensor according to claim 1, wherein the chip including a terminal of the magnetoresistive effect element, a plurality of connection pads, and a marking has a rectangular shape. 3. The magnetic sensor according to claim 2, wherein the connection pad is formed at a symmetrical position on two sides forming a corner of the chip. 4. The magnetic sensor according to claim 3, wherein the marking is formed in the vicinity of a corner facing the corners of the two sides. 5. The magnetic sensor according to claim 1, wherein one magnetoresistive element, one set of connection pads, and one marking are provided on the chip. 5. The magnetic sensor according to claim 1, wherein the chip includes at least two magnetoresistive elements, two sets of connection pads, and one marking on the chip. 6. The magnetic sensor according to claim 5, wherein four chips each having one magnetoresistive effect element are formed, and the magnetization directions of the fixed layers of adjacent magnetoresistive effect elements are different by 90 degrees in the same rotation direction. A magnetic sensor comprising a combination of magnetoresistive elements whose fixed layers have opposite magnetization directions connected in series to form a bridge circuit that outputs a one-phase output signal. 6. The magnetic sensor according to claim 5, wherein two chips each having one magnetoresistive effect element are combined with the magnetization direction of the fixed layer of the magnetoresistive effect element being 180 degrees different from each other. A magnetic sensor comprising a voltage dividing circuit connected in series. 7. The magnetic sensor according to claim 6, wherein four chips each having at least two magnetoresistive elements are formed, and the magnetization directions of the fixed layers of adjacent magnetoresistive elements are different by 90 degrees in the same rotational direction. And a magnetoresistive effect element in which the magnetization directions of the fixed layers are opposite to each other is connected in series to form a bridge circuit that outputs a multiphase output signal. 7. The magnetic sensor according to claim 6, wherein two chips each having at least two magnetoresistive effect elements formed thereon are combined with the magnetization direction of the fixed layer of the magnetoresistive effect element being different from each other by 180 degrees. A magnetic sensor, wherein magnetoresistive elements having opposite directions are connected in series to form a voltage dividing circuit.

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