JPWO2008093672A1 - Magnetic detector - Google Patents

Abstract

In particular, an object of the present invention is to provide a magnetic detection device capable of detecting a change in magnetic field strength of two or more with respect to an external magnetic field from the same direction. A first interlayer coupling magnetic field Hin1 of a first magnetoresistance effect element 23 and a second interlayer coupling magnetic field Hin2 of a second magnetoresistance effect element 28 are both positive values, and the second interlayer coupling magnetic field Hin2 is It is set to be larger than one interlayer coupling magnetic field Hin1. Thereby, the first magnetoresistive effect element 23 and the second magnetoresistive effect element 28 have different magnetic sensitivities with respect to the change in magnetic field strength of the external magnetic field from the (+ H) direction. Therefore, each detection signal generated based on the change in the electric resistance value of each magnetoresistive effect element 23, 28 is output at different magnetic field strengths. [Selection] Figure 3

Description

  The present invention relates to a magnetic detection device capable of detecting a change in magnetic field strength of 2 or more with respect to an external magnetic field from the same direction.

  The magnetic sensor includes, for example, a GMR element using a giant magnetoresistance effect (GMR effect) in which an electric resistance changes with respect to an external magnetic field.

For example, the invention described in Patent Document 1 below discloses a magnetic switch provided with a GMR element.
JP 2003-60256 A

  By the way, as an application of a magnetic sensor, there is a case where it is desired to detect a change in magnetic field strength of 2 or more with respect to an external magnetic field from the same direction.

  However, in the invention disclosed in Patent Document 1, it is impossible to detect a change in magnetic field strength of 2 or more with respect to an external magnetic field from the same direction.

  Accordingly, the present invention is to solve the above-described conventional problems, and in particular, to provide a magnetic detection device capable of detecting a change in magnetic field strength of two or more with respect to an external magnetic field from the same direction. .

The magnetic detection device of the present invention has a plurality of magnetic detection elements whose electrical characteristics change with respect to the magnetic field strength change of the external magnetic field from the same direction,
The magnetic detection elements have different magnetic sensitivities with respect to the magnetic field strength change,
Each detection signal generated based on a change in electrical characteristics of each magnetic detection element is output at different magnetic field strengths with respect to an external magnetic field from the same direction.

  This makes it possible to detect a change in magnetic field strength of 2 or more with respect to an external magnetic field from the same direction.

For example, the magnetic sensing element is a magnetoresistive effect element using a magnetoresistive effect in which an electric resistance value varies depending on a magnetization relationship between a fixed magnetic layer and a free magnetic layer facing each other across a nonmagnetic intermediate layer,
The interlayer coupling magnetic field Hin acting between the pinned magnetic layer of each magnetic sensing element and the free magnetic layer has the same sign, and the absolute value of the interlayer coupling magnetic field Hin of each magnetic sensing element is simply different in magnitude and It is preferable that the magnetic sensitivity of each magnetic detection element can be appropriately varied.

In the present invention, each magnetic detection element is incorporated in a separate bridge circuit, and one series circuit constituting each bridge circuit is connected in series with a fixed resistance element whose electric resistance does not change with respect to an external magnetic field. A common circuit, the output extraction part of the common circuit is connected to a differential amplifier,
Each of the remaining series circuits of each bridge circuit incorporates the magnetic detection element, and each output of the remaining series circuit is extracted between the output extraction unit of the remaining series circuit and the differential amplifier. A switch circuit for switching the connection of the part to the differential amplifier is provided,
It is preferable that the connection between each bridge circuit and the differential amplifier is switched by the switching operation of the switch circuit. As a result, the number of resistance elements can be reduced, and the circuit configuration can be simplified by providing only one differential amplifier.

  In the present invention, it is preferable that each detection signal is generated with a common threshold because the circuit configuration can be simplified.

  According to the magnetic detection apparatus of the present invention, it is possible to detect a change in magnetic field strength of 2 or more with respect to an external magnetic field from the same direction.

  1 and 2 are circuit configuration diagrams of the magnetic detection device 20 of the present embodiment, FIG. 3 is a graph for explaining the RH curves of the first magnetoresistive element and the second magnetoresistive element, and FIG. FIG. 5 is a partial perspective view of the magnetic detection device of the present embodiment, and FIG. 5 is a partial cross-sectional view of the magnetic detection device as viewed from the direction of the arrow when the magnetic detection device is cut in the thickness direction from the line AA shown in FIG. FIG. 6 is a partial cross-sectional view showing the layer structure of the first magnetoresistive element and the second magnetoresistive element.

  A magnetic detection device 20 according to this embodiment shown in FIG. 1 includes a resistance element unit 21 and an integrated circuit (IC) 22.

  The resistance element section 21 includes a first series circuit 26, a second fixed resistance element 27, and a first magnetoresistive effect element 23 and a first fixed resistance element 24 connected in series via a first output extraction section 25. A second series circuit 30 in which the second magnetoresistive effect element 28 is connected in series via the second output extraction unit 29, and a third fixed resistance element 31 and a fourth fixed resistance element 32 are in the third output extraction unit 33. A third series circuit 34 connected in series via is provided.

  The third series circuit 34 forms a bridge circuit with the first series circuit 26 and the second series circuit 30 as a common circuit. Hereinafter, a bridge circuit formed by connecting the first series circuit 26 and the third series circuit 34 in parallel is referred to as a first bridge circuit BC1, and the second series circuit 30 and the third series circuit 34 are connected in parallel. This bridge circuit is referred to as a second bridge circuit BC2.

  As shown in FIG. 1, in the first bridge circuit BC1, a first magnetoresistance effect element 23 and a fourth fixed resistance element 32 are connected in parallel, and the first fixed resistance element 24 and the third fixed resistance are connected. The resistance element 31 is connected in parallel. In the second bridge circuit BC2, the second fixed resistance element 27 and the third fixed resistance element 31 are connected in parallel, and the second magnetoresistance effect element 28 and the fourth fixed resistance element 32 are connected in parallel. It is connected.

  As shown in FIG. 1, the integrated circuit 22 is provided with an input terminal (power source) 39, a ground terminal 42, and two external output terminals 40 and 41. The input terminal 39, the ground terminal 42, and the external output terminals 40 and 41 are electrically connected to terminal portions on the device side (not shown) by wire bonding, die bonding or the like.

  A signal line 50 connected to the input terminal 39 and a signal line 51 connected to the ground terminal 42 are provided at both ends of the first series circuit 26, the second series circuit 30, and the third series circuit 34. Connected to each of the electrodes.

  As shown in FIG. 1, a single differential amplifier 35 is provided in the integrated circuit 22, and the third series circuit 34 of the third series circuit 34 is connected to either the + input section or the −input section of the differential amplifier 35. An output extraction unit 33 is connected. The connection between the third output extraction unit 33 and the differential amplifier 35 is described below. The first output extraction unit 25 of the first series circuit 26 and the second output extraction unit 29 of the second series circuit 30 will be described below. Unlike the connection state between the differential amplifier 35 and the differential amplifier 35, they are fixed (not connected).

  The first output extraction section 25 of the first series circuit 26 and the second output extraction section 29 of the second series circuit 30 are connected to the input section of the first switch circuit 36, respectively. The output section of the first switch circuit 36 is The differential amplifier 35 is connected to either the − input part or the + input part (the input part on the side where the third output extraction part 33 is not connected).

  As shown in FIG. 1, the output section of the differential amplifier 35 is connected to a Schmitt trigger type comparator 38, and the output section of the comparator 38 is connected to the input section of a second switch circuit 43. The output side of the switch circuit 43 is connected to the first external output terminal 40 and the second external output terminal 41 via the two latch circuits 46 and 47 and the FET circuits 54 and 55, respectively.

  Further, as shown in FIG. 1, a third switch circuit 48 is provided in the integrated circuit 22. The output part of the third switch circuit 48 is connected to a signal line 51 connected to the ground terminal 42, and the input part of the third switch circuit 48 is connected to the first series circuit 26 and the second series circuit 30. One end is connected.

  Further, as shown in FIG. 1, an interval switch circuit 52 and a clock circuit 53 are provided in the integrated circuit 22. When the switch of the interval switch circuit 52 is turned off, the power supply to the integrated circuit 22 is stopped. The on / off of the switch of the interval switch circuit 52 is interlocked with the clock signal from the clock circuit 53, and the interval switch circuit 52 has a power saving function for intermittently energizing.

  The clock signal from the clock circuit 53 is also output to the first switch circuit 36, the second switch circuit 43, and the third switch circuit 48. When receiving the clock signal, the first switch circuit 36, the second switch circuit 43, and the third switch circuit 48 are controlled so as to divide the clock signal and perform the switch operation with a very short cycle. For example, when one pulse of the clock signal is several tens of milliseconds, the switching operation is performed every several tens of micrometers.

  For example, the magnetic detection device 20 is built in a main body in which key switches are arranged in a foldable mobile phone. A magnet M is mounted on a folding portion having a display device such as a liquid crystal device.

  The location of the magnetic detection device 20 is not limited to the mobile phone, and can be used, for example, for a seat position detection unit or a seat belt attachment / detachment detection unit mounted in an automobile.

  The cross-sectional shape of the magnetic detection device 20 of this embodiment will be described with reference to FIG. As shown in FIG. 5, in the magnetic detection device 20, active elements 71 to 76 such as a differential amplifier and a comparator constituting the integrated circuit 22 and a wiring layer 77 are formed on a substrate 70. The wiring layer 77 is made of, for example, aluminum (Al).

  As shown in FIG. 5, the substrate 70 and the integrated circuit 22 are covered with an insulating layer 78 made of a resist layer or the like. A hole 78b is formed in a part of the insulating layer 78 on the wiring layer 77, and an upper surface of the wiring layer 78 is exposed from the hole 78b.

  The surface 78a of the insulating layer 78 is formed as a planarized surface, and the first magnetoresistive element 23, the second magnetoresistive element 28, and the first fixed resistive element 24 are formed on the planarized surface 78a of the insulating layer 78. The second fixed resistance element 27, the third fixed resistance element 31, and the fourth fixed resistance element 32 are formed in the meander shape shown in FIG. By forming it in a meander shape, the element resistance of each element can be increased.

  As shown in FIG. 4, electrodes 23a, 23b, 24a, 24b, 27a, 27b, 28a, 28b, 31a, 31b, 32a, and 32b are formed at both ends of each element. The electrode 23b of the first magnetoresistive effect element 23 and the electrode 24b of the first fixed resistance element 24 are connected by a first output extraction unit 25, and the first output extraction unit 25 is connected to the wiring as shown in FIG. It is electrically connected on the layer 77. Similarly, the electrode 27b of the second fixed resistance element 27 and the electrode 28b of the second magnetoresistance effect element 28 are connected by the second output extraction portion 29 and electrically connected to a wiring layer (not shown). Further, the electrode 31b of the third fixed resistance element 31 and the electrode 32b of the fourth fixed resistance element 32 are connected by the third output extraction portion 33 and are electrically connected to a wiring layer (not shown).

  As shown in FIG. 5, the element, the electrode, and the output extraction portion are covered with an insulating layer 80 made of, for example, alumina or silica. The magnetic detection device 20 is packaged with a mold resin 81.

  The first magnetoresistive element 23 and the second magnetoresistive element 28 are both GMR elements that exhibit a giant magnetoresistive effect (GMR effect) based on a change in magnetic field strength of an external magnetic field in the (+ H) direction.

  Here, the external magnetic field in the (+ H) direction indicates a certain direction, and in this embodiment, the direction is in the X1 direction shown in the drawing (see FIG. 6).

  The layer structure and RH curve of the first magnetoresistive element 23 and the second magnetoresistive element 28 will be described in detail below. FIG. 6 is a cross-sectional view when it is assumed that the magnetoresistive elements 23 and 28 are formed directly on the substrate 70. In practice, as shown in FIG. 5, the integrated circuit 22 and the insulating layer 78 are provided on the substrate 70, and the first magnetoresistive effect element 23 and the second magnetoresistive effect element 28 are provided on the insulating layer 78. .

  As shown in FIG. 6, the first magnetoresistive effect element 23 and the second magnetoresistive effect element 28 are each composed of an underlayer 60, a seed layer 61, an antiferromagnetic layer 62, a fixed magnetic layer 63, a nonmagnetic intermediate, from the bottom. Layers 64 and 67 (the nonmagnetic intermediate layer of the first magnetoresistive effect element 23 is denoted by reference numeral 64 and the nonmagnetic intermediate layer of the second magnetoresistive effect element 28 is denoted by reference numeral 67), the free magnetic layer 65, and the protective layer 66 They are stacked in order. The underlayer 60 is made of, for example, a nonmagnetic material of one or more elements selected from Ta, Hf, Nb, Zr, Ti, Mo, and W. The seed layer 61 is made of NiFeCr or Cr. The antiferromagnetic layer 62 includes an anti-ferromagnetic material containing an element α (where α is one or more of Pt, Pd, Ir, Rh, Ru, and Os) and Mn. Or, element α and element α ′ (where element α ′ is Ne, Ar, Kr, Xe, Be, B, C, N, Mg, Al, Si, P, Ti, V, Cr, Fe, Co, Ni) , Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ag, Cd, Sn, Hf, Ta, W, Re, Au, Pb, and rare earth elements are one or more elements) and It is formed of an antiferromagnetic material containing Mn. For example, the antiferromagnetic layer 62 is made of IrMn or PtMn. The pinned magnetic layer 63 and the free magnetic layer 65 are made of a magnetic material such as a CoFe alloy, a NiFe alloy, or a CoFeNi alloy. The nonmagnetic intermediate layers 64 and 67 are made of Cu or the like. The protective layer 66 is made of Ta or the like. The pinned magnetic layer 63 and the free magnetic layer 65 have a laminated ferrimagnetic structure (magnetic layer / nonmagnetic layer / magnetic layer laminated structure in which the magnetization directions of two magnetic layers sandwiching the nonmagnetic layer are antiparallel) It may be. The pinned magnetic layer 63 and the free magnetic layer 65 may have a laminated structure of a plurality of magnetic layers made of different materials.

  In the first magnetoresistive element 23 and the second magnetoresistive element 28, the antiferromagnetic layer 62 and the pinned magnetic layer 63 are formed in contact with each other. An exchange coupling magnetic field (Hex) is generated at the interface between the layer 62 and the pinned magnetic layer 63, and the magnetization direction of the pinned magnetic layer 63 is fixed in one direction. 4 and 6, the magnetization direction 63a of the pinned magnetic layer 63 is indicated by the arrow direction. In the first magnetoresistive effect element 23 and the second magnetoresistive effect element 28, the magnetization direction 63a of the fixed magnetic layer 63 is the X2 direction shown in the drawing.

  Further, the magnetization direction 65a of the free magnetic layer 65 in the absence of a magnetic field (when no external magnetic field is applied) is the X2 direction in the drawing for both the first magnetoresistance effect element 23 and the second magnetoresistance effect element 28. . Therefore, in the non-magnetic state, the magnetization direction 63a of the pinned magnetic layer 63 and the magnetization direction 65a of the free magnetic layer 65 are in a parallel state.

  As shown in FIG. 6, the film thicknesses of the nonmagnetic intermediate layers 64 and 67 are different between the first magnetoresistive effect element 23 and the second magnetoresistive effect element 28. The nonmagnetic intermediate layers 64 and 67 are made of Cu, for example, as described above, but the magnitude of the interlayer coupling magnetic field Hin acting between the pinned magnetic layer 63 and the free magnetic layer 65 by changing the Cu thickness. Changes.

  The first interlayer coupling magnetic field Hin1 acting on the first magnetoresistance effect element 23 and the second interlayer coupling magnetic field Hin2 acting on the second magnetoresistance effect element 28 have the same sign, and the first interlayer coupling magnetic field Hin1 The film thicknesses of the nonmagnetic intermediate layers 64 and 67 are adjusted so that the absolute value of is smaller than the absolute value of the second interlayer coupling magnetic field Hin2.

  FIG. 3 shows RH curves of the first magnetoresistance effect element 23 and the second magnetoresistance effect element 28. In the graph, the vertical axis represents the resistance value R, but the resistance change rate (%) may also be used. As shown in FIG. 3, when the external magnetic field is gradually increased from the zero magnetic field state (zero) in the (+ H) direction, the magnetization 6 direction 65 a of the free magnetic layer 65 of the first magnetoresistance effect element 23 and the fixed magnetism. Since the parallel state with the magnetization direction 63a of the layer 63 collapses and approaches an antiparallel state, the resistance value R of the first magnetoresistance effect element 23 gradually increases along the curve HC1 and eventually reaches the maximum resistance value. . When the external magnetic field in the (+ H) direction is gradually reduced toward zero from there, the resistance value R of the first magnetoresistive element 23 gradually decreases along the curve HC2, and eventually reaches the minimum resistance. Reach value.

  Thus, the loop portion L1 surrounded by the curves HC1 and HC2 is formed in the RH curve of the first magnetoresistance effect element 23 with respect to the change in magnetic field strength of the external magnetic field in the (+ H) direction. . The intermediate value of the maximum resistance value and the minimum resistance value of the first magnetoresistive element 23, and the center value of the spread width of the loop portion L1 is the “midpoint” of the loop portion L1. The magnitude of the first interlayer coupling magnetic field Hin1 is determined by the strength of the magnetic field from the midpoint of the loop portion L1 to the line of the external magnetic field H = 0 (Oe). As shown in FIG. 3, the first interlayer coupling magnetic field Hin1 of the first magnetoresistive effect element 23 is shifted in the direction of the external magnetic field in the (+ H) direction.

  As shown in FIG. 3, the electrical resistance value of the second magnetoresistive effect element 28 does not change at the magnetic field strength of the external magnetic field where the electrical resistance value of the first magnetoresistive effect element 23 changes. That is, the magnetization direction 65a of the free magnetic layer 65 of the second magnetoresistive effect element 28 and the magnetization direction 63a of the pinned magnetic layer 63 maintain the parallel state shown in FIG.

  When the magnetic field strength of the external magnetic field from the (+ H) direction is further increased, the magnetization direction 65a of the free magnetic layer 65 of the second magnetoresistance effect element 28 gradually moves from the X2 direction to the X1 direction. Since the parallel state of the magnetization direction 65a of the free magnetic layer 65 and the magnetization direction 63a of the pinned magnetic layer 63 collapses and approaches an antiparallel state, the resistance value R of the second magnetoresistance effect element 28 is on the curve HC3. The maximum resistance value is reached after a while. When the magnetic field strength of the external magnetic field in the (+ H) direction is gradually reduced from there, the resistance value R of the second magnetoresistance effect element 28 gradually decreases along the curve HC4, and eventually the minimum resistance value. To reach.

  Thus, the loop portion L2 surrounded by the curves HC3 and HC4 is formed in the RH curve of the second magnetoresistive element 28 with respect to the change in the magnetic field strength of the external magnetic field in the (+ H) direction. . The intermediate value of the maximum resistance value and the minimum resistance value of the second magnetoresistive element 28, and the center value of the spread width of the loop portion L2 is the “midpoint” of the loop portion L1. The magnitude of the first interlayer coupling magnetic field Hin2 is determined by the strength of the magnetic field from the midpoint of the loop portion L2 to the line of the external magnetic field H = 0 (Oe). As shown in FIG. 3, the second interlayer coupling magnetic field Hin2 of the second magnetoresistive element 28 is shifted in the direction of the external magnetic field in the (+ H) direction.

  If the magnetic field strength of the external magnetic field in the (+ H) direction is a positive value and the magnetic field strength of the external magnetic field in the (−H) direction is a negative value, the first interlayer coupling magnetic field Hin1 and the second magnetic field of the first magnetoresistance effect element 23 The second interlayer coupling magnetic field Hin2 of the magnetoresistive effect element 28 is both positive. The first interlayer coupling magnetic field Hin1 of the first magnetoresistance effect element 23 and the second interlayer coupling magnetic field Hin2 of the second magnetoresistance effect element 28 may both be negative values.

  In any case, in the present embodiment, the first interlayer coupling magnetic field Hin1 and the second interlayer coupling magnetic field Hin2 have the same sign, and the absolute value of the first interlayer coupling magnetic field Hin1 and the absolute value of the second interlayer coupling magnetic field Hin2 Are adjusted to different sizes. Accordingly, the magnetic sensitivities of the first magnetoresistive effect element 23 and the second magnetoresistive effect element 28 with respect to the magnetic field strength of the external magnetic field from the same direction are different.

  In the embodiment shown in FIG. 3, the electric resistance value of both the first magnetoresistive effect element 23 and the second magnetoresistive effect element 28 changes with respect to the magnetic field strength change of the external magnetic field from the (+ H) direction. As compared with the first magnetoresistive effect element 23, the 2 magnetoresistive effect element 28 changes its electric resistance value with a stronger magnetic field strength.

  On the other hand, the first fixed resistance element 24, the second fixed resistance element 27, the third fixed resistance element 31, and the fourth fixed resistance element 32 do not change the electric resistance value with respect to the external magnetic field.

  For example, the first fixed resistance element 24, the second fixed resistance element 27, the third fixed resistance element 31, and the fourth fixed resistance element 32 are made of the same material as the first magnetoresistance effect element 23 and the second magnetoresistance effect element 28. Unlike the first magnetoresistive element 23 and the second magnetoresistive element 28, the free magnetic layer 65 and the nonmagnetic intermediate layer 64 are reversely stacked. That is, the first fixed resistance element 24, the second fixed resistance element 27, the third fixed resistance element 31, and the fourth fixed resistance element 32 are the base layer 60, the seed layer 61, the antiferromagnetic layer 62, and the fixed magnetic layer from the bottom. 63, a free magnetic layer 65, a nonmagnetic intermediate layer 64, and a protective layer 66 are laminated in this order. Since the free magnetic layer 65 is formed in contact with the pinned magnetic layer 63, unlike the first magnetoresistive effect element 23 and the second magnetoresistive effect element 28, the magnetization does not fluctuate with respect to an external magnetic field and is no longer free. It does not function as the magnetic layer 65 (like the pinned magnetic layer 63, it is a magnetic layer whose magnetization direction is fixed).

  Thus, the first fixed resistance element 24, the second fixed resistance element 27, the third fixed resistance element 31, and the fourth fixed resistance element 32 are connected to the first magnetoresistive effect element 23 and the second magnetoresistive effect element 28. By forming with the same material configuration, the temperature coefficient (TCR) of the first magnetoresistive effect element 23 and the second magnetoresistive effect element 28 and the temperature coefficient of each fixed resistance element 24, 27, 31, 32 are varied. Can be suppressed.

Next, the principle of detecting an external magnetic field will be described.
FIG. 1 shows a circuit state in which the first bridge circuit BC1 and the first external output terminal 40 are connected, and FIG. 2 shows a circuit state in which the second bridge circuit BC2 and the second external output terminal 41 are connected. Show.

  When the external magnetic field in the (+ H) direction acting on the magnetic detection device 20 of this embodiment gradually increases from zero, first, the electrical resistance value of the first magnetoresistive effect element 23 fluctuates, and the first series circuit 26 The midpoint potential at the first output extraction unit 25 varies.

  In the circuit state shown in FIG. 1, the midpoint potential of the third output extraction unit 33 of the third series circuit 34 is set as a reference potential, and the first series circuit 26 and the third series circuit 34 are configured. A differential potential between the first output extraction unit 25 and the third output extraction unit 33 of the 1-bridge circuit BC1 is generated by the differential amplifier 35 and output to the comparator 38. In the comparator 38, the differential potential is shaped into a pulse waveform signal by a Schmitt trigger input, and the shaped detection signal is output from the first external output terminal 40 via the latch circuit 46 and the FET circuit 54.

  When a voltage higher than a predetermined voltage is input to the comparator 38, the detection signal is output from the first external output terminal 40 as an ON signal.

  FIG. 3 shows the high threshold level (threshold voltage) LV1 on the rising side of the Schmitt trigger input converted into the electric resistance value R of the magnetoresistive effect elements 23 and 28. As shown in FIG. 3, when the external magnetic field exceeds H1, the resistance value R of the first magnetoresistance effect element 23 exceeds the high threshold level LV1, and an ON signal is output.

  At this time, as shown in FIG. 2, even if the first switch circuit 36, the second switch circuit 43, and the third switch circuit 48 are switched, the electrical resistance value of the second magnetoresistive effect element 28 remains at the high threshold level LV1. Therefore, an OFF signal is output from the second external output terminal 41.

  Further, when the magnetic field strength of the external magnetic field H from the (+ H) direction is increased, the resistance value of the second magnetoresistive effect element 28 eventually fluctuates, so that the second output extraction unit 29 of the second series circuit 30 has a medium value. The point potential fluctuates.

  Now, in the circuit state shown in FIG. 2, the midpoint potential of the third output extraction unit 33 of the third series circuit 34 is set as a reference potential, and the second series circuit 30 and the third series circuit 34 are configured. A differential potential between the second output extraction unit 29 and the third output extraction unit 33 of the 2-bridge circuit BC2 is generated by the differential amplifier 35 and output to the comparator 38. In the comparator 38, the differential potential is shaped into a pulse waveform signal by a Schmitt trigger input, and the shaped detection signal is outputted from the second external output terminal 41 via the latch circuit 46 and the FET circuit 54. As shown in FIG. 3, when the external magnetic field exceeds H2, the resistance value R of the second magnetoresistive element 28 exceeds the high threshold level LV1, and an ON signal is output. At this time, even if the circuit state of FIG. 1 is switched, the resistance value R of the first magnetoresistive effect element 23 continues to exceed the high threshold level LV1, so that the ON signal continues to be output. .

  As described above, according to the present embodiment, when the magnetic field strength of the external magnetic field H in the (+ H) direction is gradually increased, it is possible to detect two strengths at a time point exceeding H1 and a point exceeding H2. It is.

  Therefore, if the magnetic detection device 20 of the present embodiment is used, two or more different intervals (distances) between the magnet M and the magnetic detection device 20 can be detected.

  In the present embodiment, as shown in FIGS. 1 and 2, one differential amplifier 35 and one comparator 38 are provided, respectively, and as shown in FIG. 3, the threshold level (threshold voltage) is set to the first bridge circuit BC1. And the second bridge circuit BC2. Therefore, the circuit configuration can be simplified.

  Moreover, in the first bridge circuit BC1 and the second bridge circuit BC2, the third series circuit 34 is a common circuit, so that the number of elements can be reduced and the magnetic detection device 20 can be reduced in size.

  1 and 2, the first fixed resistance element 24 and the second fixed resistance element 27 are changed to magnetoresistive effect elements in which the interlayer coupling magnetic field Hin is negative and the absolute value of the interlayer coupling magnetic field Hin is different. May be. As a result, a magnetic field strength of 2 or more can be detected with respect to both the (+ H) direction and the (−H) direction.

  The first magnetoresistive effect element 23 and the second magnetoresistive effect element 28 described above utilize the giant magnetoresistive effect (GMR effect), but in addition to the GMR element, an anisotropic magnetoresistive effect (AMR) is provided. It may be a TMR element using an AMR element or a tunnel magnetoresistive effect (TMR). It can also be applied to Hall elements.

  However, in this embodiment, it is preferable to use a GMR element or a TMR element. By adjusting the interlayer coupling magnetic field Hin, it is possible to easily obtain the RH curve shown in FIG. 3 and to form a plurality of magnetic detection elements having different magnetic sensitivities with respect to changes in the magnetic field strength of the external magnetic field H in the same direction. is there.

The 1st circuit block diagram of the magnetic detection apparatus of this embodiment, The 2nd circuit block diagram of the magnetic detection apparatus of this embodiment, A graph for explaining the RH curves of the first magnetoresistive element and the second magnetoresistive element; The partial perspective view of the magnetic detection apparatus of this embodiment, FIG. 4 is a partial cross-sectional view of the magnetic detection device when the magnetic detection device is cut in the thickness direction from the line AA shown in FIG. 4 and viewed from the arrow direction; The partial expanded sectional view which looked at the layer structure of the 1st magnetoresistive effect element and the 2nd magnetoresistive effect element from the same cross section as FIG.

Explanation of symbols

20 Magnetic Detection Device 21 Resistance Element Unit 22 Integrated Circuit (IC)
23 1st magnetoresistive effect element 24 1st fixed resistance element 25 1st output extraction part 26 1st series circuit 27 2nd fixed resistance element 28 2nd magnetoresistive effect element 29 2nd output extraction part 30 2nd series circuit 31 1st 3 fixed resistance element 32 4th fixed resistance element 33 3rd output extraction part 34 3rd series circuit 35 Differential amplifier 36 1st switch circuit 38 Comparator 39 Input terminal 40 1st external output terminal 41 2nd external output terminal 42 Earth terminal 43 Second switch circuit 46, 47 Latch circuit 48 Third switch circuit 53 Clock circuit 62 Antiferromagnetic layer 63 Fixed magnetic layer 64, 67 Nonmagnetic intermediate layer 65 Free magnetic layer 66 Protective layer 70 Substrate 78, 80 Insulating layer 81 Mold Resin Hin1, Hin2 Interlayer coupling magnetic field M Magnet

Claims (4)

Having a plurality of magnetic sensing elements whose electrical characteristics change with respect to the magnetic field strength change of the external magnetic field from the same direction,
The magnetic detection elements have different magnetic sensitivities with respect to the magnetic field strength change,
A magnetic detection device, wherein each detection signal generated based on a change in electrical characteristics of each magnetic detection element is output at different magnetic field strengths with respect to an external magnetic field from the same direction. The magnetic sensing element is a magnetoresistive effect element using a magnetoresistive effect in which an electric resistance value varies depending on a magnetization relationship between a fixed magnetic layer and a free magnetic layer facing each other across a nonmagnetic intermediate layer,
The interlayer coupling magnetic field Hin acting between the pinned magnetic layer of each magnetic sensing element and the free magnetic layer has the same sign, and the absolute value of the interlayer coupling magnetic field Hin of each magnetic sensing element has a different magnitude. Magnetic detection device. Each magnetic detection element is incorporated in a separate bridge circuit, and one series circuit constituting each bridge circuit is a common circuit in which fixed resistance elements whose electric resistance does not change with respect to an external magnetic field are connected in series. The output extraction unit of the common circuit is connected to a differential amplifier,
The magnetic detection elements are incorporated in the remaining series circuits of the bridge circuits, respectively, and the output outputs of the remaining series circuits are provided between the output extraction unit of the remaining series circuits and the differential amplifier. A switch circuit for switching the connection of the part to the differential amplifier is provided,
The magnetic detection device according to claim 1, wherein the connection between each bridge circuit and the differential amplifier is switched by a switching operation of the switch circuit.   The magnetic detection device according to claim 1, wherein each detection signal is generated by a common threshold value.

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