WO2008075610A1

WO2008075610A1 - Magnetic detector

Info

Publication number: WO2008075610A1
Application number: PCT/JP2007/074022
Authority: WO
Inventors: Yoshito Sasaki; Shinichi Sasaki; Naoya Hasegawa
Original assignee: Alps Electric Co., Ltd.
Priority date: 2006-12-20
Filing date: 2007-12-13
Publication date: 2008-06-26
Also published as: JPWO2008075610A1; JP5006339B2

Abstract

[PROBLEMS] To provide a magnetic detector which can perform bipolar detection through a simple element configuration. [MEANS FOR SOLVING PROBLEMS] A magnetoresistive effect element (23, 27) is formed of a multilayer structure of a first laminate (60) and a second laminate (61). The first laminate (60) is constituted by laminating a first fixed magnetic layer (65) and a first free magnetic layer (67) through a first nonmagnetic material layer (66) and has an electric resistance variable for the external magnetic field in the (+) direction. The second laminate (61) is constituted by laminating a second fixed magnetic layer (71) and a second free magnetic layer (69) through a second nonmagnetic material layer (70) and has an electric resistance variable for the external magnetic field in the (-) direction. When the external magnetic field in the (+) direction intrudes, electric resistance of the first laminate (60) varies and the external magnetic field in the (+) direction is detected and when the external magnetic field in the (-) direction intrudes, electric resistance of the second laminate (61) varies and the external magnetic field in the (-) direction is detected.

Description

Specification

Magnetic detector

Technical field

The present invention relates to a magnetic detection device including a magnetoresistive effect element, and more particularly to a magnetic detection device capable of bipolar detection.

Background art

[0002] Recently, a magnetic detection device including a magnetic detection element has been adopted for opening / closing detection of a folding cellular phone.

As the magnetic detection element, a Hall element or a magnetoresistive effect element is used. Unlike the Hall element, the magnetoresistive element can appropriately change its electric resistance even with a weak external magnetic field and can be expected to have a long life.

[0004] For the magnetoresistive effect element, a GMR element using a giant magnetoresistive effect (GMR effect) is employed.

[0005] The RH curve (hysteresis loop) 1 of the GMR element is shifted to the external magnetic field side in the (+) direction as shown in FIG. In other words, when the external magnetic field H in the (+) direction enters the GMR element, the electrical resistance value R changes along the RH curve 1 shown in Fig. 8.

Patent Document 1: Japanese Patent Laid-Open No. 2005-214900

Patent Document 2: Japanese Patent Application Laid-Open No. 2004-180286

Disclosure of the invention

Problems to be solved by the invention

However, in the GMR element having the RH curve 1 shown in FIG. 8, the electrical resistance changes with respect to the intensity change of the external magnetic field H in the (−) direction opposite to the (+) direction. do not do.

[0007] Therefore, when the external magnetic field H in the (1) direction invades, the GMR element does not change in electric resistance, and thus the external magnetic field in the (1) direction cannot be detected.

[0008] Therefore, when the folding mobile phone includes the GMR element having the RH curve 1 shown in FIG. 8, when the folding mobile phone is opened and closed, the external magnetic field H in the (+) direction acts on the GMR element from the magnet. So the magnets had to be placed properly. [0009] In addition to the GMR element having the RH curve 1 shown in FIG. 8, by using a GMR element in which the RH curve is shifted to the external magnetic field side in the (one) direction, the (+) direction and (one It is possible to detect an external magnetic field in either direction.

However, in such a case, there is a problem that the number of elements increases. In particular, the GMR element for detecting the external magnetic field in the (+) direction and the GGMR element for detecting the external magnetic field in the (one) direction are not the same configuration, such as being formed with different film thicknesses. It was necessary to manufacture. As a result, the manufacturing process becomes complicated!

[0011] In the inventions described in Patent Documents 1 and 2, it is described that the magnetic detection element incorporated in the magnetic detection device is a magnetoresistive effect element utilizing the magnetoresistive effect. In particular, the invention described in Patent Document 1 discloses a magnetic detection device capable of bipolar detection.

However, the invention described in Patent Document 1 does not disclose a specific configuration of the magnetoresistive element. That is, a specific configuration of the magnetoresistive effect element having the characteristics shown in FIG.

[0013] Therefore, the present invention has been made to solve the above-described conventional problems, and in particular, an object of the present invention is to provide a magnetic detection device that enables bipolar detection with a simple element structure.

Means for solving the problem

[0014] A magnetic detection device according to the present invention comprises:

It has a magnetoresistive effect element using a magnetoresistive effect that changes its electric resistance against an external magnetic field,

The magnetoresistive effect element has a laminated structure of a first laminated body and a second laminated body, and the first laminated body includes a first fixed magnetic layer and a first free magnetic layer formed of a first nonmagnetic material layer. And the second laminated body has a second pinned magnetic layer and a second free magnetic layer as a second non-magnetic material layer. The electrical resistance changes with respect to the external magnetic field in the (one) direction opposite to the (+) direction,

When the external magnetic field in the (+) direction enters, the external magnetic field in the (+) direction is detected by changing the electric resistance value of the first laminate, and the external magnetic field in the () direction enters. In this case, the external magnetic field in the (one) direction is detected by changing the electric resistance value of the second laminated body.

[0015] In the present invention, the magnetoresistive effect element includes a first stacked body whose electric resistance changes with respect to an external magnetic field in the (+) direction, and an electric resistance which changes with respect to the external magnetic field in the (one) direction. It is formed with a laminated structure with the second stack. As a result, bipolar detection can be realized with a simple element structure.

The magnetoresistive effect element employed in the present invention is

On the R—H graph, the horizontal axis is the magnitude of the external magnetic field H, and the vertical axis is the resistance value R of the magnetoresistive element.

A first interlayer coupling magnetic field Hinl acting between the first pinned magnetic layer and the first free magnetic layer, expressed on the external magnetic field side in the (+) direction, between the second pinned magnetic layer and the second free magnetic layer; The acting second interlayer coupling magnetic field Hin2 appears on the external magnetic field side in the (-) direction,

When the electric resistance value of the magnetoresistive effect element when the external magnetic field is zero is used as a reference, the increasing / decreasing tendency of the electric resistance value of the magnetoresistive effect element with respect to the intensity change of the external magnetic field in the (+) direction, The increase / decrease tendency of the electric resistance value of the magnetoresistive effect element with respect to the change in the strength of the external magnetic field in the direction shows a reverse tendency.

[0017] This makes it possible to appropriately detect a bipolar element with a simple element configuration. In particular, the tendency of the resistance value to increase / decrease with respect to the change in the intensity of the external magnetic field in the (+) direction and the strength of the external magnetic field in the (1) direction. Since the increase / decrease tendency of the resistance value with respect to the change shows a reverse tendency, even the direction of the detected external magnetic field can be detected.

In the present invention, two magnetoresistive effect elements are prepared, and one magnetoresistive effect element is connected in series to the first fixed resistance element via the first output extraction unit, and the other magnetoresistive effect element is provided. The resistance effect element is connected in series to the second fixed resistance element via the second output extraction section.

The fixed resistance value R3 of the first fixed resistance element is equal to the electric resistance value R1 of the magnetoresistive effect element when the external magnetic field is zero and the external magnetic field is zero when an external magnetic field in the (+) direction acts. The electric resistance of the magnetoresistive effect element changed to the maximum from the electric resistance R1 The fixed resistance value R5 of the second fixed resistance element is an electric resistance value R1 when the external magnetic field of the magnetoresistive effect element is zero, and an external magnetic field in the (one) direction. It is preferable that the value be between the electric resistance value R4 of the magnetoresistive effect element changed to the maximum from the electric resistance value R1 when the external magnetic field is zero.

In particular, the fixed resistance value R3 of the first fixed resistance element is an intermediate value between the electric resistance value R1 and the electric resistance value R2 of the magnetoresistive effect element, and the fixed resistance value of the second fixed resistance element R5 is more preferably an intermediate value between the electric resistance value R1 and the electric resistance value R4 of the magnetoresistive element.

In the present invention, by using one type of magnetoresistive effect element and two types of fixed resistance elements having different fixed resistance values, it is possible to realize a magnetic detection device capable of handling bipolar. That is, it is not necessary to use a plurality of types of magnetoresistive elements as in the prior art. It is also possible to make a circuit configuration that can detect even the direction of the acting external magnetic field.

In the present invention, a first series circuit in which a magnetoresistive effect element and a first fixed resistance element are connected in series, a second series circuit in which a magnetoresistive effect element and a second fixed resistance element are connected in series, A fixed resistance element connected in series via a third output extraction unit, and the first output extraction unit of the first series circuit and the second output extraction unit of the second series circuit one by one , Connected to the common differential output unit through the connection switching unit together with the third output extraction unit of the third series circuit,

In the connection switching unit, when the first output extraction unit and the differential output unit are connected, a first bridge circuit formed by connecting the first series circuit and the third series circuit in parallel is the difference. When the second output extraction unit and the differential output unit are connected in the connection switching unit, the second series circuit and the third series circuit are switched to the state connected to the dynamic output unit. It is preferable that the second bridge circuit formed by connecting in parallel is switched to a state in which the second bridge circuit is connected to the differential output section.

[0022] The first bridge circuit is a side that detects an external magnetic field in the (+) direction, and the second bridge circuit is a side that detects an external magnetic field in the (one) direction. In the present invention, the two bridge circuits can be obtained with a small number of elements and a simple circuit configuration. The invention's effect

[0023] In the present invention, the magnetoresistive effect element includes a first stacked body whose electric resistance changes with respect to an external magnetic field in the (+) direction, and an electric resistance which changes with respect to the external magnetic field in the (one) direction. It is formed in a laminated structure with the second laminated body. As a result, bipolar detection can be realized with a simple element structure.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a circuit configuration diagram of the magnetic detection device 20 of the present embodiment, FIG. 2 is an RH graph for explaining the RH curve of the magnetoresistive effect element, and FIG. 3 is a layer of the magnetoresistive effect element. FIG. 4 to FIG. 7 are schematic cross-sectional views showing a structure of a foldable mobile phone incorporating the magnetic detection device, which is an example for explaining the use of the magnetic detection device of the present embodiment.

A magnetic detection device 20 of the present embodiment shown in FIG. 1 includes an element configuration unit 21 and an integrated circuit (IC) 22.

[0026] The element constituent unit 21 includes a first series circuit 26, a magnetoresistive effect element 27, and a first series circuit in which a magnetoresistive effect element 23 and a first fixed resistance element 24 are connected in series via a first output extraction unit 25. 2 The second series circuit 30 in which the fixed resistance element 28 is connected in series via the second output extraction section 29, and the fixed resistance element 31 and the fixed resistance element 32 are connected in series via the third output extraction section 33. The third series circuit 34 is configured.

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 in which the first series circuit 26 and the third series circuit 34 are connected 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. The resulting bridge circuit is referred to as a second bridge circuit BC2.

As shown in FIG. 1, in the first bridge circuit BC1, a magnetoresistive effect element 23 and a fixed resistance element 32 are connected in parallel, and the first fixed resistance element 24 and the fixed resistance element 31 are connected. And are connected in parallel. In the second bridge circuit BC2, the magnetoresistive effect element 27 and the fixed resistance element 31 are connected in parallel, and the second fixed resistance element 28 and the fixed resistance element 32 are connected in parallel. Yes.

As shown in FIG. 1, the integrated circuit 22 includes an input terminal (power source) 39, ground terminals 42 and 2. Two external output terminals 40, 41 are provided. The input terminal 39, the ground terminal 42, and the external output terminals 40, 41 are electrically connected to a terminal portion on the device side (not shown) by wire bonding or die bonding.

[0030] The signal line 50 connected to the input terminal 39 and the signal line 51 connected to the ground terminal 42 are connected to both ends of the first series circuit 26, the second series circuit 30 and the third series circuit 34, respectively. It is connected to each of the electrodes provided in the section.

As shown in FIG. 1, in the integrated circuit 22, one differential amplifier (differential output unit) 35 is provided. The third output extraction unit 33 of the third series circuit 34 is connected to either the + input unit or the one input unit of the differential amplifier 35. Note that the connection between the third output extraction unit 33 and the differential amplifier 35 is fixed (not in a disconnected state).

[0032] 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 (first connection switching section) 36, respectively. ing. The output section of the first switch circuit 36 is connected to either the − input section or the + input section of the differential amplifier 35 (to the input section on the side where the third output extraction section 33 is not connected). It is 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 a second switch circuit (second connection switching). Part) It is connected to 43 input parts. Further, the output section of the second 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 (third connection switching unit) 48 is provided in the integrated circuit 22. An output part of the third switch circuit 48 is connected to a signal line 51 connected to the ground terminal 42. The input part of the third switch circuit 48 includes a first series circuit 26 and a second series circuit. One end of the circuit 30 is connected.

Further, as shown in FIG. 1, an internal 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 determined by the clock signal from the clock circuit 53. The internal switch circuit 52 has a power saving function for intermittently energizing.

The clock signal from the clock circuit 53 is also output to each of the first switch circuit 36, the second switch circuit 43, and the third switch circuit 48.

The magnetoresistive effect element 23 and the magnetoresistive effect element 27 have the same layer structure. The magnetoresistive elements 23 and 27 are formed of a laminated structure of a first laminated body 60 and a second laminated body 61. The laminated structure of the magnetoresistive effect elements 23 and 27 will be described with reference to FIG.

As shown in FIG. 3, the magnetoresistive effect elements 23 and 27 are arranged on the installation surface 62 from below from the seed layer 63, the first antiferromagnetic layer 64, the first pinned magnetic layer 65, and the first nonmagnetic layer. Material layer 66, first free magnetic layer 67, intermediate separation layer 68, second free magnetic layer 69, second nonmagnetic material layer 70, second pinned magnetic layer 71, second antiferromagnetic layer 72, and protective layer 73 Are stacked in this order.

As shown in FIG. 3, the first laminate 60 is composed of a first antiferromagnetic layer 64, a first pinned magnetic layer 65, a first nonmagnetic material layer 66, and a first free magnetic layer 67. The The second laminated body 61 includes a second free magnetic layer 69, a second nonmagnetic material layer 70, a second pinned magnetic layer 71, and a second antiferromagnetic layer 72. The first stacked body 60 and the second stacked body 61 are magnetically separated by an intermediate separating layer 68.

As shown in FIG. 3, the first pinned magnetic layer 65 has a laminated ferrimagnetic structure in which a first magnetic layer 65a, a nonmagnetic intermediate layer 65b, and a second magnetic layer 65c are laminated in this order from the bottom. The second pinned magnetic layer 71 has a laminated ferrimagnetic structure in which the second magnetic layer 71c, the nonmagnetic intermediate layer 71b, and the first magnetic layer 71a are laminated in this order from the bottom.

[0041] The magnetization directions of the first magnetic layers 65a and 71a and the second magnetic layers 65c and 71c constituting the laminated ferrimagnetic structure are antiparallel.

[0042] The seed layer 63 is formed of NiFeCr or Cr. The first antiferromagnetic layer 64 and the second antiferromagnetic layer 72 are composed of the element α (where α is one or more of Pt, Pd, Ir, Rh, Ru, Os). Or anti-ferromagnetic material containing Mn, or element α and element a ′ (where elements are 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 1 Seeds or two or more elements) and Mn Made of antiferromagnetic material. For example, the first antiferromagnetic layer 64 and the second antiferromagnetic layer 72 are made of IrMn or PtMn. The first magnetic layer 65a, 71a, the second magnetic layer 65c, 71c, the first free magnetic layer 67, and the second free magnetic layer 69 are each formed of a magnetic material such as a CoFe alloy, a NiFe alloy, or a CoFeNi alloy. . The first nonmagnetic material layer 66 and the second nonmagnetic material layer 70 are made of Cu, for example. The nonmagnetic intermediate layers 65b and 71b are made of, for example, Ru. The intermediate separation layer 68 is made of Cu, for example. The protective layer 73 is made of Ta, for example.

[0043] When the right direction on the paper is the (+) direction and the left direction on the paper is the (one) direction, as shown in FIG. 3, the magnetization directions of the first magnetic layers 65a and 71a are the (+) direction and the second magnetic layer. The magnetization directions of the layers 65c and 71c are (one) direction. The magnetizations of the first magnetic layers 65a and 7la and the second magnetic layers 65c and 71c are fixed so that they do not fluctuate due to an external magnetic field!

FIG. 3 shows a no-magnetic field state in which an external magnetic field is not acting. As shown in FIG. 3, in the absence of a magnetic field, the magnetization direction of the first free magnetic layer 67 is the (one) direction, and the magnetization direction of the second free magnetic layer 69 is the (+) direction. The magnetizations of the free magnetic layers 67 and 69 are changed by an external magnetic field.

[0045] The giant magnetoresistive effect (GMR effect) includes the second magnetic layer 65c, 71c and the free magnetic layer.

It is expressed in relation to the magnetization direction with 67 and 69. That is, when the magnetization directions of the second magnetic layers 65c and 71c and the free magnetic layers 67 and 69 are in a parallel state, the electric resistance value becomes the minimum value, and the second magnetic layers 65c and 71c and the free magnetic layers 67 , 69 is the maximum value when the magnetization direction is antiparallel.

[0046] Now, when the external magnetic field H acts in the (+) direction, the magnetization of the first free magnetic layer 67 of the first stacked body 60 changes. On the other hand, since the magnetization direction of the second free magnetic layer 69 is the (+) direction, the magnetization does not fluctuate even when the external magnetic field H in the (+) direction acts. Therefore, the electrical resistance value of the second laminated body 61 remains constant.

[0047] As the magnetic field strength of the external magnetic field H in the (+) direction gradually increases, the magnetization direction of the first free magnetic layer 67 gradually changes to the (+) direction. As a result, the magnetization relationship between the first free magnetic layer 67 and the second magnetic layer 65c gradually changes from the parallel state to the antiparallel state, and the electric resistance value R of the magnetoresistive effect elements 23 and 27 is as shown in FIG. 1RH curve gradually along C1 It grows big.

On the other hand, when the external magnetic field H acts in the (one) direction, the magnetization of the second free magnetic layer 69 of the second stacked body 61 changes. On the other hand, since the magnetization direction of the first free magnetic layer 67 is the (one) direction, the magnetization does not fluctuate even when the external magnetic field H in the (one) direction acts. Therefore, the electrical resistance value of the first laminated body 60 remains constant.

[0049] When the magnetic field strength of the external magnetic field H in (1) direction gradually increases, the magnetization direction of the second free magnetic layer 69 gradually changes to (1) direction. As a result, the magnetization relationship between the second free magnetic layer 69 and the second magnetic layer 71c gradually changes from the antiparallel state to the parallel state, and the electric resistance value R of the magnetoresistive effect elements 23 and 27 is as shown in FIG. Gradually get smaller along 2RH curve C2.

[0050] As shown in FIG. 2, the first RH curve C1 and the second RH curve C2 have a loop shape having a predetermined width (meaning that there is hysteresis).

[0051] The magnitude of the first interlayer coupling magnetic field Hinl is determined by the strength of the magnetic field from the center of the first RH curve C1 formed in a loop shape to the line of the external magnetic field H = 0 (Oe). This first interlayer coupling magnetic field Hinl acts between the first pinned magnetic layer 65 and the first free magnetic layer 67 and appears on the external magnetic field side in the (+) direction on the RH graph. is doing.

[0052] The magnitude of the second interlayer coupling magnetic field Hin2 is determined by the strength of the magnetic field from the center of the second RH curve C2 formed in a loop shape to the line of the external magnetic field H = 0 (Oe). This second interlayer coupling magnetic field Hin2 acts between the second pinned magnetic layer 71 and the second free magnetic layer 69 and appears on the external magnetic field side in the (-) direction on the RH graph. is doing.

The interlayer coupling magnetic fields Hinl and Hin2 described above can be obtained by adjusting the film thickness of the first nonmagnetic material layer 66 and the second nonmagnetic material layer 70, adjusting the interface roughness, or the like.

[0054] The magnetoresistive elements 23 and 27 described above are GMR elements using the giant magnetoresistive effect (GMR effect), but are TMR elements using the tunnel magnetoresistive effect (TMR effect). Also good.

In FIG. 3, the force of the pinned magnetic layers 65 and 71 having a laminated ferrimagnetic structure may be other than that, for example, a single layer structure or a laminated structure of magnetic layers.

As shown in FIG. 1, the magnetoresistive effect elements 23 and 27 are fixed resistance elements 24 and 28, respectively. They are connected in series.

As shown in FIG. 2, the fixed resistance value R3 of the first fixed resistance element 24 connected in series to the magnetoresistive effect element 23 is the electric resistance of the magnetoresistive effect element 23 when the external magnetic field H is zero. It is adjusted to be an intermediate value between the gas resistance value R1 and the maximum electric resistance value R2 of the magnetoresistive element 23 when the external magnetic field H in the (+) direction acts!

Further, the fixed resistance value R5 of the second fixed resistance element 28 connected in series to the magnetoresistive effect element 27 is, as shown in FIG. 2, when the external magnetic field H of the magnetoresistive effect element 27 is zero. It is adjusted to be an intermediate value between the electric resistance value R1 at the time and the minimum electric resistance value R4 of the magnetoresistive effect element 27 when the external magnetic field in the (one) direction is applied.

For example, the fixed resistance elements 24 and 28 have the same material layer structure as the magnetoresistive effect elements 23 and 27 shown in FIG. 3, but the stacking order is different and the electric resistance does not change with respect to the external magnetic field. Formed with structure. In such a case, it is preferable because variations in the temperature coefficient (TCR) between the fixed resistance elements 24 and 28 and the magnetoresistive effect elements 23 and 27 can be suppressed, and the operational stability can be improved.

[0060] The fixed resistance elements 31 and 32 constituting the third series circuit 34 also have the same material layer structure as that of the magnetoresistive effect elements 23 and 27, for example, like the fixed resistance elements 24 and 28. However, the stacking order is different and the electrical resistance does not change against an external magnetic field. At this time, the fixed resistance values of the fixed resistance elements 31 and 32 are adjusted to be the same value.

The magnetoresistive effect elements 23 and 27 and the fixed resistance elements 24, 28, 31 and 32 are provided on the surface of the magnetic detection device 20 capable of sensing an external magnetic field. The magnetoresistive effect elements 23, 27 and the fixed resistance elements 24, 28, 31, 32 are formed in a meander shape. Thereby, the element resistance of each element can be increased and the current consumption can be reduced.

Instead of FIG. 1, the fixed resistance elements 31 and 32 constituting the third series circuit 34 are integrated into an integrated circuit.

22 may be incorporated. At this time, it is preferable that the fixed resistance elements 31 and 32 are formed of a high resistance material to more appropriately reduce current consumption. For example, the fixed resistance elements 31 and 32 are made of Si.

Next, the detection principle of the external magnetic field will be described. As shown in FIG. 1, when the first output extraction unit 25 and the differential amplifier 35 are connected by the first switch circuit 36, the first bridge circuit BC1 is connected to the differential amplifier 35. At this time, the differential amplifier 35 and the first external output terminal 40 are connected by the second switch circuit 43, and the first series circuit 26 and the ground terminal 42 are connected by the third switch circuit 48. Has been.

The magnitude of the external magnetic field H acting on the magnetic detection device 20 is within the “use range” shown in FIG. Within the “use range”, an external magnetic field that is strong enough to change the magnetization direction of the pinned magnetic layers 65 and 71 does not act. That is, the magnetizations of the pinned magnetic layers 65 and 71 remain fixed.

First, in the circuit state of FIG. 1, when an external magnetic field H in the (+) direction acts on the magnetic detection device 20 of the present embodiment, the electrical resistance value R of the magnetoresistive effect element 23 is shown in FIG. Gradually increase from R1 along the 1st RH curve C1.

[0066] When the electric resistance value R of the magnetoresistive effect element 23 gradually increases from R1 due to the intensity change of the external magnetic field H in the (+) direction, and eventually exceeds the fixed resistance value R3 of the first fixed resistance element 24 Based on the differential potential generated by the differential amplifier 35, the comparator 38 generates an ON signal (magnetic field detection signal), and the ON signal is output from the first external output terminal 40.

[0067] The first switch circuit 36, the second switch circuit 43, and the third switch circuit 48 are clock circuits.

The switch operates in response to the clock signal from 53. When the second output extraction unit 29 and the differential amplifier 35 are connected by the first switch circuit 36, the second bridge circuit BC2 is connected to the differential amplifier 35. At this time, the differential amplifier 35 and the second external output terminal 41 are connected by the second switch circuit 43, and the second series circuit 30 and the ground terminal 42 are connected by the third switch circuit 48. .

[0068] In the circuit state described above, when an external magnetic field H in one direction acts on the magnetic detection device 20 of the present embodiment, the electric resistance value R of the magnetoresistive effect element 27 changes from R1 to the second RH shown in FIG. Gradually decrease along curve C2.

[0069] The electric resistance value R of the magnetoresistive effect element 27 gradually decreases from R1 due to the intensity change of the external magnetic field H in the (one) direction, and eventually falls below the resistance straight R5 of the second fixed resistance element 28. When turned, the comparator 38 generates an ON signal (magnetic field detection signal) based on the differential potential generated by the differential amplifier 35, and the ON signal is output from the second output terminal 41.

As described above, the magnetic detection device 20 of the present embodiment includes the magnetoresistive effect elements 23 and 27 as shown in FIG.

This is formed by a laminated structure of the first laminated body 60 and the second laminated body 61 shown in FIG. The first laminated body 60 has a structure using a magnetoresistive effect in which the electrical resistance changes with respect to the external magnetic field H in the (+) direction, and the second laminated body 61 has an external magnetic field in the (one) direction. Thus, the structure uses the magnetoresistive effect that changes the electrical resistance.

Therefore, by using the magnetoresistive effect elements 23 and 27, the external magnetic field H in either the (+) direction or the (one) direction acts on the magnetic detection device 20. External magnetic field H can be detected. That is, bipolar detection is possible.

In the present embodiment, the magnetoresistive effect elements 23 and 27 are composed of one type of magnetoresistive effect element. That is, as shown in FIG. 1, two magnetoresistive elements 23 and 27 are provided. Since the magnetoresistive elements 23 and 27 have the same layer structure (the film thickness of each layer is also the same at this time). It can be formed by the same manufacturing process, and can be manufactured easily and appropriately.

As shown in FIG. 2, the first pinned magnetic layer 65 and the first free magnetic layer constituting the first laminate 60

The first interlayer coupling magnetic field Hin 1 acting between 67 appears on the external magnetic field side in the (+) direction on the RH graph. In addition, as shown in FIG. 2, the second interlayer coupling magnetic field Hin2 acting between the second fixed magnetic layer 71 and the second free magnetic layer 69 constituting the second stacked body 61 is shown on the RH graph. It appears on the external magnetic field side in the direction (1)!

[0074] Then, as shown in FIG. 2, the magnetic field strength of the external magnetic field H in the (+) direction when the electric resistance value R1 of the magnetoresistive effect element 23, 27 at the position where the external magnetic field H is zero is used as a reference. The increase and decrease tendency of the electric resistance value of the magnetoresistive effect elements 23 and 27 with respect to the change, and Shows the reverse trend. That is, when the external magnetic field in the (+) direction gradually increases, the electric resistance values of the magnetoresistive effect elements 23 and 27 show a tendency to increase gradually from R1, while the external magnetic field in the (1) direction. As H increases gradually, the electrical resistance values of the magnetoresistive elements 23 and 27 tend to decrease gradually from R1. The magnetoresistive effect elements 23 and 27 have a step-type RH curve including the first RH curve C1 and the second RH curve C2 shown in FIG. As a result, the magnetic detection device 20 compatible with bipolar detection can be realized with a simple circuit configuration, and the action direction of the external magnetic field can be detected.

[0076] As shown in Fig. 2, it is possible to detect the action direction of the external magnetic field in the first RH in which the electrical resistance values of the magnetoresistive elements 23 and 27 change with respect to the external magnetic field H in the (+) direction. The resistance change area of the curve C1 is different from the resistance change area of the second RH curve C2 in which the electric resistance values of the magnetoresistive elements 23 and 27 change with respect to the external magnetic field H in the (one) direction. Power is also.

As shown in FIG. 1, two external output terminals 40 and 41 are provided. The first external output terminal 40 is connected to the first bridge circuit BC1. In the first bridge circuit BC1, the external magnetic field H in the (+) direction acts and the electric resistance value of the magnetoresistive effect element 23 is When the fixed resistance value R3 of the first fixed resistance element 24 shown in FIG. 2 is exceeded, an ON signal is output from the first external output terminal 40. In other words, an OFF signal is always output from the first external output terminal 40 when the electric resistance value of the magnetoresistive effect element 23 is lower than the fixed resistance R3 of the first fixed resistance element 24. On the other hand, the second external output terminal 41 is connected to the second bridge circuit BC2. In the second bridge circuit BC2, the external magnetic field H in the (one) direction is applied, and the electric resistance of the magnetoresistive effect element 27 is When the resistance value is less than the fixed resistance R5 of the second fixed resistance element 28 shown in FIG. 2, an ON signal is output from the second external output terminal 41. In other words, when the electric resistance value of the magnetoresistive effect element 27 exceeds the fixed resistance value R4 of the second fixed resistance element 28, an OFF signal is always output from the first external output terminal 40.

[0078] Therefore, when the ON signal is output from the first external output terminal 40 (in this case, the OFF signal is output from the second external output terminal 41), the external magnetic field H in the (+) direction is magnetic. If it can be identified that it is acting on the detection device 20 and an ON signal is output from the second external output terminal 41 and V, (in this case, an OFF signal is output from the first external output terminal 40), ( It can be identified that the external magnetic field H in the direction of −) acts on the magnetic detector 20.

[0079] As shown in FIG. 2, the fixed resistance value R3 of the first fixed resistance element 24 indicates that the external magnetic field H is zero. It is preferably an intermediate value between the electric resistance value Rl of the magnetoresistive effect element 23 at the time and the maximum resistance value R2 of the magnetoresistive effect element 23 when the external magnetic field H in the (+) direction acts. The fixed resistance value R5 of the second fixed resistance element 28 is the magnetic resistance value R1 of the magnetoresistive effect element 27 when the external magnetic field H is zero and the magnetic resistance when the external magnetic field H in the (one) direction acts. It is preferably an intermediate value with respect to the maximum resistance value R4 of the resistance effect element 27.

Accordingly, the magnetic detection device 20 compatible with bipolar detection can be realized appropriately. In addition to the above, by making the magnitude of the first interlayer coupling magnetic field Hinl and the second interlayer coupling magnetic field Hin2 equal, the output timing of the ON signal when the external magnetic field H in the (+) direction is applied, 1) The output timing of the ON signal when the external magnetic field H in the direction is applied can be set to be the same.

Further, as shown in FIG. 1, the magnetic detection device 20 of the present embodiment uses the first bridge circuit BC1 as the midpoint potential of the third series circuit 34 in which fixed resistance elements 31 and 32 are connected in series, It is shared as the reference potential for the second bridge circuit BC2. Then, the connection between the first output extraction part 25 of the first series circuit 26 constituting the first bridge circuit BC1 and the differential amplifier 35, and the second of the second series circuit 30 constituting the second bridge circuit BC2. A first switch circuit 36 for alternately switching the connection between the output extraction unit 29 and the differential amplifier 35 is provided in the integrated circuit 22.

[0082] As described above, the magnetic detection device 20 of the present embodiment conventionally uses the third series circuit 34 as a common circuit in both the first bridge circuit BC1 and the second bridge circuit BC2. The number of elements can be reduced as compared with FIG.

[0083] Further, in the present embodiment, only by providing one differential amplifier 35, the state where the first bridge circuit BC1 and the differential amplifier 35 are connected, and the second bridge circuit BC2 and the differential amplifier 35 are connected. The ability to obtain the differential potential in the differential amplifier 35 from the first bridge circuit BC1 and the second bridge circuit BC2, respectively, with a simple circuit configuration, as appropriate. I can do it.

As described above, according to the present embodiment, the number of elements can be reduced and the circuit configuration can be simplified in the bipolar sensor.

In the present embodiment, when the first bridge circuit BC1 and the differential amplifier 35 are connected by the first switch circuit 36, the first switch circuit 48 The column circuit 26 and the ground terminal 42 are connected. When the second bridge circuit BC2 and the differential amplifier 35 are connected by the first switch circuit 36, the third switch circuit 48 connects the second series circuit 30 and the ground terminal 42. Is connected. As a result, no current flows through the second series circuit 30 when the first bridge circuit BC1 and the differential amplifier 35 are connected. Further, when the second bridge circuit BC2 and the differential amplifier 35 are connected, no current flows through the first series circuit 26. Therefore, current consumption can be reduced and detection sensitivity can be improved.

[0086] The third switch circuit 48 is provided between the input terminal 39 and the first series circuit 26, and between the input terminal 39 and the second series circuit 30, together with the ground terminal 42 side or instead of the ground terminal 42 side. It's set up! /!

The bipolar detection-compatible magnetic detection device 20 according to the present embodiment can be used, for example, for opening / closing detection of a folding mobile phone.

As shown in FIG. 4, the foldable mobile phone 90 has a configuration in which a first member (display housing) 91 and a second member (operation housing) 92 are connected so as to be openable and closable. A liquid crystal display, a receiver, and the like are provided on the surface of the first member 91 facing the second member 92. Various operation buttons, a microphone, and the like are provided on the surface of the second member 92 facing the first member 91. FIG. 4 shows a state in which the foldable mobile phone 90 is closed. As shown in FIG. 4, the first member 91 includes a magnet 94, and the second member 92 includes the magnetic detection device 20 of the present embodiment. Built-in. As shown in FIG. 4, in the closed state, the magnet 94 and the magnetic detection device 20 are arranged at positions facing each other! Alternatively, the magnetic detection device 20 may be arranged at a position shifted in a direction parallel to the approach direction of the external magnetic field from the position facing the magnet 94.

In FIG. 4, an external magnetic field (+ H) in the (+) direction generated from the magnet 94 is transmitted to the magnetic detection device 20, and the magnetic detection device 20 transmits the external magnetic field (+ H). Thus, it is detected that the folding cellular phone 90 is in a closed state.

On the other hand, when the folding cellular phone 90 is opened as shown in FIG. 5, as the first member 91 moves away from the second member 92, the external magnetic field (+ H) transmitted to the magnetic detection device 20 gradually increases. As the size increases, the external magnetic field (+ H) transmitted to the magnetic detector 20 eventually becomes zero. Mouth. When the magnitude of the external magnetic field (+ H) transmitted to the magnetic detection device 20 becomes a predetermined magnitude or less, it is detected that the foldable mobile phone 90 is in an open state, for example, The control unit built in the cellular phone 90 is controlled so that the backlight on the back side of the liquid crystal display and the operation buttons shines.

[0091] The magnetic detection device 20 of the present embodiment is a bipolar compatible sensor. That is, in Fig. 4, the N pole of the magnet 94 is on the left side of the figure and the S pole is on the right side of the figure, and when the polarity is reversed as shown in Fig. 6 (N pole is on the right side and S pole is on the left side) The direction of the external magnetic field (−H) exerted on the magnetic detection device 20 is reversed from the direction of the external magnetic field (+ H) in FIG. In this embodiment, even when force is applied, when the cellular phone 90 is opened as shown in FIG. 7 from the state in which the folding cellular phone 90 is closed as shown in FIG. 6, it is detected appropriately. Like

Accordingly, since the magnet 94 can be arranged regardless of the polarity of the external magnetic field, there is no restriction on the arrangement of the magnet 94, and assembly is facilitated.

[0093] In the above open / close detection method, even if the direction of the external magnetic field cannot be identified, it is only necessary to detect a change in the external magnetic field using a bipolar circuit. For example, the external output terminals 40 and 41 shown in FIG. Or just one.

That is, for example, when the second switch circuit 43 shown in FIG. 1 is eliminated and one signal line from the comparator 38 to the latch circuit 46 and the FET circuit 54 to the external output terminal 40 is formed, the external output From the terminal 40, both a detection signal for an external magnetic field in the (+) direction and a detection signal for an external magnetic field in the (one) direction can be obtained. At this time, it is not possible to identify the direction of the external magnetic field, but there is a need for open / close detection that the direction of the external magnetic field does not have to be identified. The configuration may be simplified.

[0095] In the folding mobile phone 90 of the type (turnover type) that can flip the first member 91 from the open state of FIG. 5 (turnover type), the camera mode is activated by inverting the first member 91. There is a need to activate different functions in the non-inverted state and the inverted state. In such a case, in the non-inverted state and the inverted state, the direction of the external magnetic field H acting on the magnetic detection device 20 is reversed. Identify the direction of the partial magnetic field. That is, as already described, two external output terminals 40 and 41 are provided as shown in FIG. 1, and the first external output terminal 40 is connected to the first bridge circuit BC1 that detects the external magnetic field H in the (+) direction. The second external output terminal 41 is connected to the second bridge circuit BC2 that detects the external magnetic field H in the (one) direction. Thus, by identifying the external output terminal that outputs the ON signal, it is possible to identify the direction of the external magnetic field.

In FIG. 3, the right side of the paper is described as the (+) direction, and the left side of the paper is described as the (1) direction. However, the left side of the paper may be the (1) direction, and the right side of the paper may be the (+) direction. In such a case, the laminated body 61 is the first laminated body in which the electrical resistance changes with respect to the external magnetic field H in the (+) direction, and the laminated body 60 changes in the electrical resistance with respect to the external magnetic field H in the (one) direction. This is the second laminate. The RH curve has a line-symmetric shape with the horizontal axis shown in Fig. 2 as the axis of symmetry. That is, the electrical resistance of the magnetoresistive elements 23 and 27 gradually decreases from R1 as the external magnetic field in the (+) direction increases, and gradually increases from R1 as the external magnetic field in the (one) direction increases. Become.

The magnetic detection device 20 of the present embodiment may be used for opening / closing detection of a portable electronic device such as a game machine in addition to detection of opening / closing of a folding mobile phone. In addition to the above open / close detection, this embodiment can be used for applications that require a magnetic detection device 20 that supports bipolar detection, such as a slide sensor.

Brief Description of Drawings

FIG. 1 is a circuit configuration diagram of a magnetic detection device of the present embodiment,

[FIG. 2] RH graph for explaining the RH curve of the magnetoresistive effect element of the present embodiment. [FIG. 3] Partial sectional view showing the layer structure of the magnetoresistive effect element of the present embodiment. A partial cross-sectional view of a cut surface cut from a normal direction),

FIG. 4 is an example for explaining the use of the magnetic detection device of the present embodiment (a partial schematic view of a foldable mobile phone incorporating the magnetic detection device, showing a state in which the phone is closed);

[FIG. 5] An example for explaining the use of the magnetic detection device of the present embodiment (a partial schematic view of a foldable mobile phone incorporating the magnetic detection device, showing a state in which the phone is opened), FIG. 6 is an example for explaining the use of the magnetic detection device of the present embodiment (a partial schematic view of a foldable mobile phone incorporating the magnetic detection device, with the arrangement of magnets reversed from FIG. 4; The phone is closed)

FIG. 7 is an example for explaining the use of the magnetic detection device of the present embodiment (a partial schematic view of a foldable mobile phone incorporating the magnetic detection device, with the arrangement of magnets reversed from FIG. 5; The phone is open)

8] R—H graph for explaining the RH curve of the magnetoresistive effect element provided in the conventional magnetic detection device,

Explanation of symbols

20 Magnetic detector

21 Element configuration

22 Integrated circuits

23, 27 Magnetoresistive element

24 1st fixed resistance element

28 2nd fixed resistance element

31, 32 Fixed resistance element

26 1st series circuit

30 Second series circuit

34 3rd series circuit

35 differential amplifier

36 1st switch circuit

38 Comparator

40, 41 External output terminal

43 Second switch circuit

48 3rd switch circuit

60 First laminate

61 Second laminate

63 Seed layer 64 First antiferromagnetic layer

65 First pinned magnetic layer

66 First non-magnetic material layer

67 1st free magnetic layer

68 Middle separation layer

69 Second free magnetic layer

70 Second nonmagnetic material layer

71 Second pinned magnetic layer

72 Second antiferromagnetic layer

73 Protective layer

90 Noon A 3¾ ^ Fortune

91 1st part (Display housing)

92 2nd part (control enclosure)

94 Magnet

CI 1st RH curve

C2 2nd RH curve

Hinl 1st interlayer coupling field Hin2 2nd interlayer coupling field

Claims

The scope of the claims

[1] It has a magnetoresistive element using a magnetoresistive effect in which the electric resistance changes with respect to an external magnetic field,

When the external magnetic field in the (+) direction enters, the external magnetic field in the (+) direction is detected by changing the electric resistance value of the first stacked body, and the external magnetic field in the () direction enters. In some cases, the external magnetic field in the (one) direction is detected by changing the electric resistance value of the second laminated body.

[2] On the R—H graph, the horizontal axis is the magnitude of the external magnetic field H, and the vertical axis is the resistance value R of the magnetoresistive element.

When the electric resistance value of the magnetoresistive effect element when the external magnetic field is zero is used as a reference, the increasing / decreasing tendency of the electric resistance value of the magnetoresistive effect element with respect to the intensity change of the external magnetic field in the (+) direction, The magnetic detection device according to claim 1, wherein the increasing / decreasing tendency of the electric resistance value of the magnetoresistive effect element with respect to a change in strength of the external magnetic field in the direction shows a reverse tendency.

[3] Two magnetoresistive elements are prepared, one of the magnetoresistive elements is connected in series to the first fixed resistive element via the first output extraction unit, and the other magnetoresistive element is The fixed resistance value R3 of the first fixed resistance element is connected in series to the second fixed resistance element via the second output extraction unit, and the electric resistance value of the magnetoresistive effect element when the external magnetic field is zero When R1 and the external magnetic field in the (+) direction act, the external magnetic field Is a value between the electrical resistance value R1 of the magnetoresistive effect element maximally changed from the electrical resistance value Rl when zero is zero, and the fixed resistance value R5 of the second fixed resistance element is the magnetoresistive effect When the external magnetic field of the element is zero, and when the external magnetic field in the (one) direction is applied, the magnetoresistance effect changes to the maximum from the electric resistance value R1 when the external magnetic field is zero. 3. The magnetic detection device according to claim 2, wherein the magnetic detection device has a value between the electric resistance value R4 of the element.

[4] The fixed resistance value R3 of the first fixed resistance element is an intermediate value between the electric resistance value R1 and the electric resistance value R2 of the magnetoresistive effect element, and the fixed resistance value R5 of the second fixed resistance element is 4. The magnetic detection device according to claim 3, wherein the magnetoresistance effect element is an intermediate value between an electric resistance value R1 and an electric resistance value R4.

[5] A first series circuit in which a magnetoresistive effect element and a first fixed resistance element are connected in series, a second series circuit in which a magnetoresistive effect element and a second fixed resistance element are connected in series, and a fixed resistance element And a third series circuit connected in series via the third output extraction unit,

One of the first output extraction unit of the first series circuit and the second output extraction unit of the second series circuit are respectively connected to the common differential output unit via the connection switching unit. Connected with the take-out part,

In the connection switching unit, when the first output extraction unit and the differential output unit are connected, a first bridge circuit formed by connecting the first series circuit and the third series circuit in parallel is the difference. When the second output extraction unit and the differential output unit are connected in the connection switching unit, the second series circuit and the third series circuit are switched to the state connected to the dynamic output unit. 5. The magnetic detection device according to claim 3, wherein a second bridge circuit formed by connecting in parallel is switched to a state of being connected to the differential output unit.