JP2009258042A - Rotation detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation detecting device that is equipped with a magnet and a non-contact type magnetic sensor having a magnetoresistance effect element and can detect a rotational direction. <P>SOLUTION: In a reference state, the magnetic sensor 13 at a fixing side is disposed at a portion on a line extending from a rotational center of a rotary section 10 in a gravity direction, and the magnets 11, 12 supported by the rotary section 10 are respectively placed at positions separated from the rotational center in right and left sides of the magnetic sensor 13. The rotary section 10 is rotated from the reference state to the gravity direction along with rotation of a clockwise direction or a counterclockwise direction so as to maintain a constant posture in the gravity direction. At that time, relative positions of the magnetic sensor 13 and the magnets 11, 12 are close to each other so that the magnetic sensor 13 receives an external magnetic field from the magnets and an electric resistance value of the magnetoresistance effect element varies. As a result, the rotational direction can be detected by an output from the magnetic sensor 13 in accordance with the variation in the electric resistance value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rotation detection device including a magnet and a non-contact type magnetic sensor having a magnetoresistive effect element and capable of detecting a rotation direction.

  For example, when using e-mail or the Internet on a mobile phone, the mobile phone is usually used in a standing state so that the user's line of sight is almost perpendicular to the screen display of the mobile phone. Here, the state in which the mobile phone is set up is referred to as a reference state.

  In addition, the mobile phone itself may be rotated from the reference state and tilted 90 degrees in the horizontal direction to use a camera built in the mobile phone or to watch television. At this time, when the mobile phone is rotated clockwise or counterclockwise from the reference state and tilted by 90 degrees, the display of the mobile phone is always maintained in the same direction with respect to the user's line of sight. There is a need to know the direction of rotation.

  In the invention described in Patent Document 1, an imaging vertical direction detection unit is built in a mobile phone. However, the imaging vertical direction detection unit includes a casing made of glass or the like as described in [0037] column of Patent Document 1, mercury contained in the casing, an electrode pair, and the like. In addition, an inexpensive and small non-contact type rotation detection device cannot be obtained. In addition, there is a problem that the safety cannot be maintained by using mercury and the rotation detection with higher accuracy cannot be performed.

  In the invention described in Patent Document 2, a movable sphere is enclosed in a cylindrical case as described in [0043], and the movement of the sphere due to gravity is used as a signal by a contact piece or the like. A tilt sensor is disclosed. However, since it is a contact-type tilt sensor, its reliability is poor.

In the invention described in Patent Document 3, an inclination sensor using a Hall element and a magnet is disclosed. As described in [0029] column of Patent Document 3, the rotating body including the magnet is provided with a defect portion, and as described in [0032] column, the defect portion is detected by the Hall element. Thus, it is possible to detect that the vehicle body is tilted more than a predetermined angle. However, the invention described in Patent Document 3 does not detect whether the vehicle body is tilted clockwise or counterclockwise. Further, it is considered that a plurality of magnetic sensors are required to detect the rotation direction using a magnetic sensor provided with a Hall element.
JP 2001-54084 A JP 2006-243621 A JP 2007-118868 A

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and in particular, an object of the present invention is to provide a rotation detection device that includes a magnet and a non-contact type magnetic sensor having a magnetoresistive effect element and can detect the rotation direction. .

The present invention includes a magnet and a non-contact type magnetic sensor including a magnetoresistive effect element whose electric resistance value changes with respect to an external magnetic field, and one of the magnet and the magnetic sensor is a rotating part. In the rotation detection device that is supported and the other is supported by the fixed part,
At least two magnets and one magnetic sensor are used, and the rotating part is supported to be rotatable in the direction of gravity,
In the reference state, the magnetic sensor is arranged in the direction of gravity from the rotation center of the rotation unit, and the magnet is arranged at a position away from the rotation center on both the left and right sides of the magnetic sensor,
As the clockwise or counterclockwise rotation from the reference state, the rotating part rotates toward the gravitational direction and maintains a constant posture in the gravitational direction. At this time, the relative position of the magnetic sensor relative to the magnet As the position approaches, the magnetic sensor receives an external magnetic field from the magnet and the electric resistance value of the magnetoresistive effect element changes, and the rotation direction can be known from the output from the magnetic sensor based on this electric resistance change. It is characterized by.

  According to the present invention, a non-contact type magnetic sensor having a plurality of magnets and a magnetoresistive effect element is provided, and when the rotating portion rotates clockwise or counterclockwise from the reference state, the rotating portion rotates. Due to the movement, the relative position between the magnetic sensor and the magnet approaches, so that the magnetic sensor receives an external magnetic field from the magnet and the electric resistance value of the magnetoresistive element changes. The direction of rotation can be detected by the output from the magnetic sensor based on this change in electrical resistance.

In the present invention, the magnetoresistive element has a pinned magnetic layer and a free magnetic layer laminated on the pinned magnetic layer via a nonmagnetic layer, and the magnetization of the pinned magnetic layer is pinned in one direction. And
In the reference state, one magnet has an external magnetic field parallel to the fixed magnetization direction of the fixed magnetic layer of the magnetoresistive effect element when the relative position with the magnetic sensor approaches, so that the other magnet The magnets are preferably magnetized so that an external magnetic field antiparallel to the fixed magnetization direction of the fixed magnetic layer of the magnetoresistive element acts when the relative position with the magnetic sensor approaches.
Thereby, it is possible to know the rotation direction appropriately with a simple configuration.

In the present invention, the magnetic sensor includes a first magnetoresistive element using a magnetoresistive effect in which an electric resistance changes with respect to an external magnetic field in one direction, and an external magnetic field in a direction opposite to the one direction. A second magnetoresistive element utilizing a magnetoresistive effect that changes electrical resistance, a first output terminal, and a second output terminal,
A signal based on the electrical resistance change of the first magnetoresistive element is output from the first output terminal, and a signal based on the electrical resistance change of the second magnetoresistive element is output from the second output terminal. preferable.

  As described above, a two-output magnetic sensor capable of bipolar detection can be obtained. By using this magnetic sensor, the direction of rotation can be detected by using only one magnetic sensor.

  According to the rotation detection device of the present invention, a rotation direction can be detected by including a magnet and a non-contact type magnetic sensor having a magnetoresistive effect element.

  FIG. 1 is a front view of a mobile phone, FIG. 2 is a principle diagram of rotation direction detection of the rotation detection device in this embodiment, and FIG. 3 is a conceptual diagram (front view) of a rotation detection device showing an embodiment different from FIG. 4) is a side view of the rotation detection device in the present embodiment, FIG. 5 is a side view of the rotation detection device in the present embodiment different from FIG. 4, and FIGS. 6 and 7 are magnetic sensors in the present embodiment. FIG. 8 is a graph (RH curve) for explaining the hysteresis characteristic of the first magnetoresistance effect element, and FIG. 9 is a graph (R for explaining the hysteresis characteristic of the second magnetoresistance effect element). -H curve), FIG. 10 is a partial cross-sectional view showing the layer structure of the first magnetoresistive effect element and the second magnetoresistive effect element, and FIG. 11 is a partial cross section mainly for explaining the layer structure of the fixed resistance element. Figure.

  The X1-X2 direction, the Y1-Y2 direction, and the Z1-Z2 direction in the figure are orthogonal to each other.

  FIG. 1A shows a state in which the foldable mobile phone 1 is opened. As shown in FIG. 1A, for example, the mobile phone 1 has a configuration in which a first housing 2 and a second housing 3 are connected via a hinge portion 4. The first housing 2 is provided with a screen display unit 5 and a speaker 8. The second housing 3 is provided with various operation buttons 6 and a microphone 7.

  The Z1 direction shown in FIG. 1 is the direction of gravity. Therefore, FIG. 1A shows a state in which the mobile phone 1 is set in a direction substantially orthogonal to the ground surface. Here, the state of FIG. 1A is referred to as a “reference state”.

  Assume that a flower picture is displayed on the screen display unit 5 in the reference state as shown in FIG. As shown in FIG. 1B, when the mobile phone 1 is rotated 90 degrees clockwise (CW direction) from the reference state, the flower picture displayed in the reference state is 90 degrees counterclockwise (CCW direction). ), And as shown in FIG. 1C, when the mobile phone 1 is rotated 90 degrees counterclockwise (CCW direction) from the reference state, the flower picture displayed in the reference state is 90 degrees. By rotating in the clockwise direction (CW direction), the orientation of the flower picture is always kept constant with respect to the user's line of sight.

  In the present embodiment, the mobile phone 1 includes a rotation detection device 9 for detecting the rotation direction when the mobile phone 1 is rotated clockwise or counterclockwise from the reference state of FIG. Yes. For example, the rotation detection device 9 is built in the first housing 2 having the screen display unit 5.

  2A is a reference state of FIG. 1A, FIG. 2B is a state when the cellular phone 1 is rotated 90 degrees clockwise as shown in FIG. 1B, and FIG. ) Is a conceptual diagram (front view) of the rotation detection device 9 showing a state when the mobile phone 1 is rotated 90 degrees counterclockwise as shown in FIG. As shown in FIG. 2A, the rotation detection device 9 includes a pair of magnets 11 and 12 and one magnetic sensor 13. As shown in FIG. 2A, the magnets 11 and 12 are fixedly supported on both sides in the X1-X2 direction of the rotating portion 10 formed in a substantially semicircular shape. The rotating unit 10 is supported so as to be rotatable about a rotating shaft 14. In the state of Fig.2 (a), the rotation part 10 is balanced in the gravity direction. The magnets 11 and 12 are arranged at equal intervals on the left and right sides of the rotation shaft 14 in the X1-X2 direction in the reference state of FIG. The shape of the rotation part 10 is not limited. The rotating unit 10 can be formed into a circular shape, a sector shape, or the like. Further, when a weight (not shown) is installed in the gravity direction A from the rotation shaft 14 shown in FIG. 2A so that the weight is always positioned directly below the rotation shaft 14 by gravity, the rotation portion 10 The posture stability can be improved more effectively.

  As shown in FIG. 2A, the magnetic sensor 13 is provided at a position away from the rotation center of the rotation unit 10 in the gravity direction A and at a position away from the surface of the rotation unit 10 in the Y direction. It is done. The magnetic sensor 13 is installed on the fixed portion side provided separately from the rotating portion 10. In the front view of the reference state shown in FIG. 2A, the linear distance from the rotating shaft 14 to the magnetic sensor 13 and the linear distance from the rotating shaft 14 to the magnets 11 and 12 are substantially the same.

  When the mobile phone 1 is rotated 90 degrees clockwise as shown in FIG. 1B from the reference state of FIG. 1A, the rotating unit 10 is counterclockwise 90 about the rotating shaft 14 as the center of rotation. Rotate degrees. Therefore, the rotating unit 10 in FIG. 2B in which the mobile phone 1 is rotated 90 degrees in the clockwise direction maintains a constant posture in the direction of gravity, as in FIG. 2A in the reference state. .

  Further, when the mobile phone 1 is rotated 90 degrees counterclockwise as shown in FIG. 1C from the reference state of FIG. 1A, the rotation unit 10 rotates clockwise about the rotation shaft 14 as the rotation center. Turn 90 degrees. Therefore, the rotating unit 10 in FIG. 2C in which the mobile phone 1 is rotated 90 degrees counterclockwise has a constant posture in the gravitational direction as in FIG. 2A which is the reference state. keep.

  On the other hand, since the magnetic sensor 13 is on the fixed portion side, if the mobile phone 1 is rotated 90 degrees clockwise, it is rotated 90 degrees clockwise from the reference state together with the mobile phone as shown in FIG. If the mobile phone 1 is turned 90 degrees counterclockwise, the mobile phone 1 is turned 90 degrees counterclockwise from the reference state together with the mobile phone as shown in FIG.

  When the mobile phone 1 is rotated 90 degrees clockwise as shown in FIG. 2B, the magnetic sensor 13 is in a positional relationship facing the upper side of the magnet 12, and the mobile phone 1 is placed as shown in FIG. In a state rotated 90 degrees counterclockwise, the magnetic sensor 13 is in a positional relationship facing the upper side of the magnet 11.

  Thereby, in each state of FIG. 2B and FIG. 2C, an external magnetic field acts on the magnetic sensor 13 from the magnets 11 and 12. As will be described later, the magnetic sensor 13 is provided with a magnetoresistive element using a magnetoresistive effect in which an electric resistance value changes with respect to an external magnetic field. Therefore, the electric resistance value of the magnetoresistive effect element is fluctuated by receiving an external magnetic field, and the rotation direction can be known from the output based on the change in the electric resistance. Then, a rotation direction detection signal is transmitted from the rotation detection device 9 to a control circuit provided in the mobile phone 1, and the image displayed on the screen display unit 5 always corresponds to the user's line of sight. Image rotating means for rotating the image clockwise or counterclockwise based on the detection signal so as to have the same orientation.

Next, the circuit configuration of the magnetic sensor 13 will be described with reference to FIG.
The magnetic sensor 13 of this embodiment includes a sensor unit 21 and an integrated circuit (IC) 22.

  The sensor unit 21 includes a first series circuit 26 in which a first magnetoresistance effect element 23 and a fixed resistance element 24 are connected in series via a first output extraction unit (connection unit) 25, and a second magnetoresistance effect. A third series circuit 30 in which the element 27 and the fixed resistance element 28 are connected in series via a third output extraction unit (connection unit) 29 is provided.

  In the integrated circuit 22, a second series circuit 34 in which the fixed resistance element 31 and the fixed resistance element 32 are connected in series via the second output extraction unit 33 is provided.

  The second series circuit 34 forms a bridge circuit with each of the first series circuit 26 and the third series circuit 30 as a common circuit. Hereinafter, a bridge circuit in which the first series circuit 26 and the second series circuit 34 are connected in parallel is a bridge circuit in which the first bridge circuit BC1, the third series circuit 30 and the second series circuit 34 are connected in parallel. Is referred to as a second bridge circuit BC2.

  As shown in FIG. 6, 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 control circuit side of the mobile phone 1 (not shown) by wire bonding, die bonding, or the like.

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

  As shown in FIG. 6, one differential amplifier 35 is provided in the integrated circuit 22, and the second output of the second series circuit 34 is taken out to either the + input part or the −input part of the differential amplifier 35. The unit 33 is connected.

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

  As shown in FIG. 6, 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 (second connection switching section) 43. Further, the output side 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. The FET circuits 54 and 55 constitute a logic circuit.

  Further, as shown in FIG. 6, a third switch circuit 48 is provided in the integrated circuit 22. The output portion of the third switch circuit 48 is connected to a signal line 51 connected to the ground terminal 42, and one end portions of the first series circuit 26 and the third series circuit 30 are connected to the input portion of the third switch circuit 48. It is connected.

  Further, as shown in FIG. 6, 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 conducting the energized state.

  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 the first switch circuit 36, the second switch circuit 43, and the third switch circuit 48 receive the clock signal, the clock signal is divided and controlled so as to perform the switching 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.

  The first magnetoresistive effect element 23 is a magnetoresistive effect element that exhibits a magnetoresistive effect based on a change in the intensity of an external magnetic field (+ H) in one direction, while the second magnetoresistive effect element 27 is (+ H) The magnetoresistive element exhibits a magnetoresistive effect based on a change in magnetic field strength of an external magnetic field (-H) whose direction is opposite.

  The layer structure and hysteresis characteristics of the first magnetoresistive element 23 and the second magnetoresistive element 27 will be described in detail below.

  As shown in FIG. 10, the first magnetoresistive effect element 23 and the second magnetoresistive effect element 2 are both the base layer 60, the seed layer 61, the antiferromagnetic layer 62, the fixed magnetic layer 63, and the nonmagnetic intermediate layer from the bottom. 64, the free magnetic layers 65 and 67 (the free magnetic layer of the second magnetoresistance effect element 27 is denoted by reference numeral 67), and the protective layer 66 are laminated in this order. The underlayer 60 is made of, for example, a nonmagnetic material such as one or more elements of Ta, Hf, Nb, Zr, Ti, Mo, and W. The seed layer 61 is formed of NiFeCr or Cr. The antiferromagnetic layer 62 is an antiferromagnetic 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 Mn And an antiferromagnetic material containing For example, the antiferromagnetic layer 62 is made of IrMn or PtMn. The fixed magnetic layer 63 and the free magnetic layers 65 and 67 are formed of a magnetic material such as a CoFe alloy, a NiFe alloy, or a CoFeNi alloy. The nonmagnetic intermediate layer 64 is 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 layers 65 and 67 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. ). The pinned magnetic layer 63 and the free magnetic layers 65 and 67 may have a laminated structure of a plurality of magnetic layers made of different materials.

  In the first magnetoresistive effect element 23 and the second magnetoresistive effect element 27, the antiferromagnetic layer 62 and the fixed magnetic layer 63 are formed in contact with each other. An exchange coupling magnetic field (Hex) is generated at the interface with the magnetic layer 63, and the magnetization direction of the fixed magnetic layer 63 is fixed in one direction. In FIG. 10, the pinned magnetization direction 63a of the pinned magnetic layer 63 is indicated by the arrow direction. In the first magnetoresistive element 23 and the second magnetoresistive element 27, the fixed magnetization direction 63a of the fixed magnetic layer 63 is the same direction. FIG. 10 shows the magnetoresistive elements 23 and 27 in the reference state shown in FIG. 2A. For example, the fixed magnetization direction 63a of the fixed magnetic layer 63 of the magnetoresistive elements 23 and 27 faces the X1 direction. ing.

  On the other hand, the magnetization directions of the free magnetic layers 65 and 67 are different between the first magnetoresistance effect element 23 and the second magnetoresistance effect element 27. As shown in FIG. 10, in the first magnetoresistive effect element 23, the magnetization direction 65a of the free magnetic layer 65 is the X1 direction shown in the figure, and is the same direction as the fixed magnetization direction 63a of the fixed magnetic layer 63. In the element 27, the magnetization direction 67 a of the free magnetic layer 67 is the X2 direction shown in the figure, and is antiparallel to the fixed magnetization direction 63 a of the fixed magnetic layer 63.

  FIG. 8 is an RH curve showing the hysteresis characteristic of the first magnetoresistive element 23. In the graph of the figure, the vertical axis is the resistance value R, but it may be the resistance change rate (%). As shown in FIG. 8, when the external magnetic field gradually increases in the (+ H) direction (X2 direction in FIG. 10) from the non-magnetic state (zero), the magnetization direction 65a of the free magnetic layer 65 and the fixed magnetic layer Since the parallel state of 63 with the fixed magnetization direction 63a collapses and approaches an antiparallel state, the resistance value R of the first magnetoresistive element 23 gradually increases along the curve HR1, and the external magnetic field in the (+ H) direction Is gradually decreased toward zero, the resistance value R of the first magnetoresistance effect element 23 gradually decreases along the curve HR2.

  As described above, the first magnetoresistance effect element 23 is formed with the hysteresis loop HR surrounded by the curves HR1 and HR2 with respect to the magnetic field strength change 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 effect element 23, and the center value of the spread width of the hysteresis loop HR is the “midpoint” of the hysteresis loop HR. The magnitude of the first interlayer coupling magnetic field Hin1 is determined by the strength of the magnetic field from the midpoint of the hysteresis loop HR to the line of the external magnetic field H = 0 (Oe). As shown in FIG. 8, in the first magnetoresistance effect element 23, the first interlayer coupling magnetic field Hin1 is shifted in the magnetic field direction of (+ H).

  On the other hand, when an external magnetic field in the (−H) direction (X1 direction in FIG. 10) is exerted, the magnetization direction 65a of the free magnetic layer 65 of the first magnetoresistance effect element 23 does not change, but the second magnetoresistance effect element. 27, the magnetization 67a of the free magnetic layer 67 varies, and the resistance value of the second magnetoresistive element 27 varies.

  FIG. 9 is an RH curve showing the hysteresis characteristic of the second magnetoresistance effect element 27. As shown in FIG. 9, when the external magnetic field gradually increases in the negative direction from the no magnetic field state (zero), the anti-parallel state of the magnetization 67a of the free magnetic layer 67 and the fixed magnetization direction 63a of the fixed magnetic layer 63. The resistance value R of the second magnetoresistive element 27 gradually decreases along the curve HR3, while the external magnetic field in the (−H) direction is gradually directed to zero. When changed, the resistance value R of the second magnetoresistance effect element 27 gradually increases along the curve HR4.

  As described above, the second magnetoresistance effect element 27 is formed with the hysteresis loop HR surrounded by the curves HR3 and HR4 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 27, and the center value of the spread width of the hysteresis loop HR is the “midpoint” of the hysteresis loop HR. The magnitude of the second interlayer coupling magnetic field Hin2 is determined by the strength of the magnetic field from the midpoint of the hysteresis loop HR to the line of the external magnetic field H = 0 (Oe). As shown in FIG. 9, in the second magnetoresistive element 27, the second interlayer coupling magnetic field Hin2 is shifted in the (−H) magnetic field direction.

  Thus, in the present embodiment, the first interlayer coupling magnetic field Hin1 of the first magnetoresistance effect element 23 is shifted in the (+ H) magnetic field direction, while the second interlayer coupling magnetic field of the second magnetoresistance effect element 27 is. Hin2 is shifted in the (−H) magnetic field direction.

  In order to obtain the interlayer coupling magnetic fields Hin1 and Hin2 having the opposite signs described with reference to FIGS. 8 and 9, for example, the gas flow rate (gas pressure) and power during the plasma treatment (PT) on the surface of the nonmagnetic intermediate layer 64 are obtained. Adjust the value appropriately. It is known that the interlayer coupling magnetic field Hin changes depending on the magnitude of the gas flow rate (gas pressure) and the magnitude of the power value. The interlayer coupling magnetic field Hin can be changed from a positive value to a negative value as the gas flow rate (gas pressure) or power value is increased. Further, the magnitude of the interlayer coupling magnetic field Hin also changes with the film thickness of the nonmagnetic intermediate layer 64. Alternatively, the magnitude of the interlayer coupling magnetic field Hin can be changed when the antiferromagnetic layer / pinned magnetic layer / nonmagnetic intermediate layer / free magnetic layer are stacked in this order from the bottom. But you can adjust it.

  In the first magnetoresistive effect element 23, the first interlayer coupling magnetic field Hin1 has a (+ H) value. In such a case, the interaction between the fixed magnetic layer 63 and the free magnetic layer 65 tries to make the magnetizations parallel to each other. Work. In the second magnetoresistive element 27, the second interlayer coupling magnetic field Hin2 has a (−H) value. In such a case, the magnetizations of the fixed magnetic layer 63 and the free magnetic layer 67 should be antiparallel. The interaction that works. Then, by generating an exchange coupling magnetic field (Hex) in the same direction between the antiferromagnetic layer 62 and the pinned magnetic layer 63 of each magnetoresistive effect element 23, 27 by heat treatment in the magnetic field, each magnetoresistive effect element. The pinned magnetization direction 63a of the pinned magnetic layers 63 of 27 and 27 can be pinned in the same direction, and the interaction described above works between the pinned magnetic layer 63 and the free magnetic layers 65 and 67, and the magnetization state of FIG. It becomes.

  The first magnetoresistive effect element 23 and the second magnetoresistive effect element 27 described above use the giant magnetoresistive effect (GMR effect). In addition to the GMR element, the nonmagnetic intermediate layer 64 is formed of an insulating material. A TMR element using the tunneled magnetoresistive effect (TMR) may be used.

  On the other hand, the fixed resistance element 24 connected in series to the first magnetoresistive effect element 23 is formed of the same material layer as the first magnetoresistive effect element 23 except that the stacking order is different from that of the first magnetoresistive effect element 23, for example. Is done. That is, as shown in FIG. 11, the fixed resistance element 24 includes a base layer 60, a seed layer 61, an antiferromagnetic layer 62, a first magnetic layer 63, a second magnetic layer 65, a nonmagnetic intermediate layer 64, and a protective layer from the bottom. The layers are stacked in the order of 66. The first magnetic layer 63 corresponds to the pinned magnetic layer 63 constituting the first magnetoresistive effect element 23, and the second magnetic layer 65 corresponds to the free magnetic layer 65 constituting the first magnetoresistive effect element 23. . As shown in FIG. 11, in the fixed resistance element 24, the first magnetic layer 63 and the second magnetic layer 65 are continuously stacked on the antiferromagnetic layer 62 to form the first magnetic layer 63 and the second magnetic layer 65. Both magnetizations are fixed by an exchange coupling magnetic field (Hex) generated between the antiferromagnetic layer 62 and the second magnetic layer 65 is exposed to an external magnetic field like the free magnetic layer 65 of the first magnetoresistance effect element 23. On the other hand, there is no magnetization fluctuation.

  As shown in FIG. 11, each layer of the fixed resistance element 24 is made of the same material as each layer corresponding to the first magnetoresistance effect element 23, so that the element resistances of the first magnetoresistance effect element 23 and the fixed resistance element 24 are obtained. Can be made substantially the same, and the potential of the first output extraction section 25 in the absence of a magnetic field can be appropriately controlled to the midpoint potential. In addition, variation in the temperature coefficient (TCR) of the first magnetoresistive effect element 23 and the temperature coefficient of the fixed resistance element 24 can be suppressed. Can be improved. It is more preferable that not only the material but also the thickness of each layer corresponding to the first magnetoresistive element 23 is equal to each layer of the first magnetoresistive element 23.

  Although not shown, the fixed resistance element 28 connected in series with the second magnetoresistive effect element 27 differs from the second magnetoresistive effect element 27 only in the stacking order, as described above. Are formed of the same material layer.

  On the other hand, the resistance element that constitutes the second series circuit 34 is composed only of the fixed resistance element and does not include the magnetoresistive effect element. It is not necessary to form the same material layer as the element.

  That is, the fixed resistance elements 31 and 32 are not particularly limited in layer structure as long as they are fixed resistance elements having substantially the same element resistance formed of the same material layer. For example, the fixed resistance elements 31 and 32 can be formed of silicon (Si) having a very high sheet resistance. The element resistances of the fixed resistance elements 31 and 32 can be increased to about several tens of kΩ.

Next, the principle of detecting an external magnetic field will be described.
First, a case where an external magnetic field is not acting on the magnetic sensor 13 of the present embodiment will be described. The reference state shown in FIG. 2A corresponds to this case. In such a case, the resistance values of the first magnetoresistive effect element 23 and the second magnetoresistive effect element 27 do not change. When each of the first switch circuit 36, the second switch circuit 43, and the third switch circuit 48 receives the clock signal from the clock circuit 53, the first switch circuit 36 is connected to the first series circuit 26 as shown in FIG. The first output extraction unit 25 and the differential amplifier 35 are connected, the second switch circuit 43 is connected between the comparator 38 and the first external output terminal 40, and the third switch circuit 48 is connected to the first series circuit 26 and the ground terminal. 42, the external magnetic field detection circuit state in the (+ H) direction connecting between the two, and as shown in FIG. 7, the first switch circuit 36 connects between the third output extraction unit 29 of the third series circuit 30 and the differential amplifier 35. The second switch circuit 43 connects between the comparator 38 and the second external output terminal 41, and the third switch circuit 48 connects between the third series circuit 30 and the ground terminal 42 in the (−H) direction. To the magnetic field detection circuit state, it switched to every several tens of μsec.

  If the external magnetic field does not reach, in the external magnetic field detection circuit state in the (+ H) direction of FIG. 6, the differential potential between the first output extraction unit 25 and the second output extraction unit 33 of the first bridge circuit BC1, and In the external magnetic field detection circuit state in the (−H) direction of FIG. 7, the differential potential between the third output extraction unit 29 and the second output extraction unit 33 of the second bridge circuit BC2 is almost the same. When the differential potential is output from the amplifier 35 toward the comparator 38, the comparator 38 receives a Schmitt trigger input, for example, a high-level signal passes through the latch circuits 46 and 47, the FET circuit 54, and the first external output terminal 40. And output from the second external output terminal 41.

  Next, when the mobile phone 1 is rotated clockwise from the reference state of FIG. 1A as shown in FIG. 1B, the rotation detecting device 9 is changed from the reference state of FIG. ) In a state rotated clockwise by 90 degrees. As already described, the rotation unit 10 constituting the rotation detection device 9 rotates 90 degrees counterclockwise about the rotation shaft 14 as a rotation center, and always maintains a constant posture with respect to the direction of gravity. On the other hand, the magnetic sensor 13 on the fixed part side rotates 90 degrees clockwise together with the mobile phone 1, so that it approaches the magnet 12 positioned on the left side in the drawing with respect to the rotation shaft 14. At this time, an external magnetic field (+ H) acting antiparallel to the fixed magnetization direction 63a of the fixed magnetic layer 63 of the first magnetoresistive effect element 23 constituting the magnetic sensor 13 acts. Therefore, the resistance value of the first magnetoresistive element 23 varies, and the potential at the first output extraction unit 25 of the first series circuit 26 varies from the midpoint potential.

  Now, in the state of the external magnetic field detection circuit in the (+ H) direction shown in FIG. The differential potential between the first output extraction unit 25 and the second output extraction unit 33 of the first bridge circuit BC1 configured by the above 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. At this time, if the external magnetic field in the (+ H) direction is greater than or equal to a predetermined level, the detection signal is controlled to be output from the first external output terminal 40 as a low level signal.

  On the other hand, when the external magnetic field in the (+ H) direction is acting, even if the external magnetic field detection circuit state in the (−H) direction in FIG. As in the case where the magnetic field is not acting, the second external output terminal 41 is controlled to output a high level signal.

  Thus, at the first external output terminal 40, when an external magnetic field in a certain (+ H) direction acts on the first external output terminal 40, the signal level changes from the high level signal to the low level signal. By obtaining the level signal, it is possible to know that the mobile phone 1 has rotated in the clockwise direction in FIG. 1B from the reference state shown in FIG.

  Next, when the mobile phone 1 is rotated counterclockwise as shown in FIG. 1C from the reference state of FIG. 1A, the rotation detecting device 9 is changed from the reference state of FIG. c) Shifts to a state of 90 ° counterclockwise rotation. As described above, the rotation unit 10 constituting the rotation detection device 9 rotates 90 degrees clockwise around the rotation shaft 14 and maintains a constant posture with respect to the direction of gravity. On the other hand, the magnetic sensor 13 on the fixed part side rotates 90 degrees counterclockwise together with the mobile phone 1, so that it is relatively close to the magnet 12 positioned on the right side of the drawing with respect to the rotation shaft 14. At this time, an external magnetic field (−H) is applied which is parallel to the fixed magnetization direction 63 a of the fixed magnetic layer 63 of the second magnetoresistive effect element 27 constituting the magnetic sensor 13. Therefore, the resistance value of the second magnetoresistive element 27 varies, and the potential at the third output extraction unit 29 of the third series circuit 30 varies from the midpoint potential.

  Now, in the external magnetic field detection circuit state in the (−H) direction shown in FIG. 7, the midpoint potential of the second output extraction unit 33 of the second series circuit 34 is used as a reference potential, and the third series circuit 30 and the second series circuit are used. The differential potential between the third output extraction unit 29 and the second output extraction unit 33 of the second bridge circuit BC2 configured by the reference numeral 34 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 second external output terminal 41 via the latch circuit 46 and the FET circuit 54. At this time, if the external magnetic field in the (−H) direction is greater than or equal to a predetermined magnitude, the detection signal is controlled to be output from the second external output terminal 41 as a low level signal.

  On the other hand, when the external magnetic field (−H) in the (−H) direction is acting, the first magnetoresistive element 23 changes in resistance even when the external magnetic field detection circuit state in the (+ H) direction in FIG. 6 is switched. Therefore, as in the case where no external magnetic field is acting, the first external output terminal 40 is controlled to output a high level signal.

  In this way, at the second external output terminal 41, when an external magnetic field in the (−H) direction above a certain level acts, the signal level changes from the high level signal to the low level signal. By obtaining the low level signal, it can be known that the mobile phone 1 has rotated counterclockwise in FIG. 1C from the reference state shown in FIG.

  FIG. 3 is a front view of the rotation detection device 9 in the same reference state as FIG. In the embodiment shown in FIG. 3, magnets 70 and 71 and auxiliary magnets 72 and 73 are provided on both the left and right sides of the rotating unit 10. As shown in FIG. 3, the magnets 70 and 71 are arranged at a position away from the center of rotation by a predetermined angle θ1 with respect to the direction of gravity. The angle θ1 is smaller than 90 degrees. As shown in FIG. 3, auxiliary magnets 72 and 73 are provided on substantially the left and right sides of the rotation shaft 14. By providing the auxiliary magnets 72 and 73, the external magnetic field H can be applied in a long space from the magnets 70 and 71 to the auxiliary magnets 72 and 73.

  When the rotation detection device 9 shown in FIG. 3 is used, the rotation detection device 9 is rotated more than an arbitrary angle from the reference state of FIG. 1 (a) to the 90 ° rotation of FIG. 1 (b) or 1 (c). In addition, an external magnetic field H can be applied to the magnetic sensor 13. For example, if the arrangement of the magnets is adjusted so that the external magnetic field H acts when rotated 60 degrees from the reference state of FIG. 1A, the cellular phone 1 is rotated 60 degrees or more so that FIGS. As shown in (c), the screen of the screen display unit 5 can be rotated 90 degrees or in the counter-rotating direction. If the rotation detection device 9 shown in FIG. 3 is used, the angle range over which the external magnetic field H acts is wide, so even if the screen is tilted slightly, the screen will not rotate (switch) each time. , Operational stability can be improved.

  The arrangement of the magnets 70 and 71 and the auxiliary magnets 72 and 73 can be arbitrarily set. Further, by increasing the number of magnets, the angle range in which the external magnetic field H acts can be expanded. For example, even when the mobile phone 1 is rotated slightly more than 90 degrees clockwise or counterclockwise, the external magnetic field H can be applied to maintain the wide screen display shown in FIGS. 1 (b) and 1 (c). As described above, it is preferable that the angle range in which the external magnetic field H acts on the magnetic sensor 13 is increased to a rotation angle of 90 degrees or more by arranging magnets above the left and right side positions of the rotation shaft 14.

  As shown in FIG. 4, the rotating shaft 14 is fixedly supported on the substrate 74, and the rotating portion 10 is rotatably attached to the rotating shaft 14. Further, a fixed portion (substrate) 75 is provided at a position away from the rotating portion 10, and the magnetic sensor 13 is fixedly supported by the fixed portion 75.

  Alternatively, as shown in FIG. 5, the magnetic sensor 13 is fixedly supported on a fixed portion (substrate) 76, the rotating shaft 14 is fixedly supported on the fixed portion 76, and the rotating portion is rotatable on the rotating shaft 14. 10 may be attached.

  As described above, according to the present embodiment, two or more magnets 11 and 12 and one non-contact type magnetic sensor 13 having a magnetoresistive effect element are provided, and the mobile phone 1 is moved clockwise from the reference state or When rotated counterclockwise, the relative position between the magnetic sensor 13 and the magnets 11, 12 approaches due to the rotation of the rotating unit 10, whereby the magnetic sensor 13 receives the external magnetic field H from the magnets 11, 12. Thus, the electric resistance value of the magnetoresistive element changes. The direction of rotation can be detected from the output from the magnetic sensor 13 based on this change in electrical resistance.

  In particular, in the present embodiment, the rotation direction can be appropriately detected with a simple configuration by using the two-output magnetic sensor 13 corresponding to the bipolar described in FIG.

  In the above-described embodiment, the magnet is attached to the rotating part 10 and the magnetic sensor 13 is attached to the fixed part side, but the reverse may be possible.

  Further, the rotation detection device 9 of this embodiment can be used for electronic devices other than the mobile phone 1.

It is a front view of a mobile phone, (a) is a reference state, (b) is rotated 90 degrees clockwise, (c) is a diagram when rotated 90 degrees counterclockwise, It is a principle diagram of the rotation direction detection of the rotation detection device in the present embodiment, (a) is a reference state, (b) is when the mobile phone is rotated 90 degrees clockwise as shown in FIG. (C) is a diagram when the mobile phone is rotated 90 degrees counterclockwise as shown in FIG. FIG. 2 is a conceptual diagram (front view) of a rotation detection device showing an embodiment different from FIG. A side view of the rotation detection device in the present embodiment, The side view of the rotation detection apparatus in this embodiment different from FIG. A circuit diagram of the magnetic sensor of the present embodiment ((+ H) when detecting an external magnetic field), A circuit diagram of the magnetic sensor of the present embodiment ((−H) when detecting an external magnetic field), A graph (RH curve) for explaining the hysteresis characteristics of the first magnetoresistance effect element; A graph (RH curve) for explaining the hysteresis characteristic of the second magnetoresistance effect element; The fragmentary sectional view which shows the layer structure of a 1st magnetoresistive effect element and a 2nd magnetoresistive effect element, Partial sectional view mainly for explaining the layer structure of the fixed resistance element,

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cellular phone 2 1st housing | casing 3 2nd housing | casing 5 Screen display part 9 Rotation detection apparatus 10 Rotating part 11, 12, 70, 71 Magnet 13 Magnetic sensor 14 Rotating shaft 72, 73 Auxiliary magnets 74, 75, 76 Substrate 21 Sensor unit 22 Integrated circuit (IC)
23 1st magnetoresistive effect element 24, 28, 31, 32 Fixed resistance element 25 1st output extraction part 26 1st series circuit 27 2nd magnetoresistive effect element 29 3rd output extraction part 30 3rd series circuit 33 2nd output Extraction unit 34 Second series circuit 35 Differential amplifier 36 First switch circuit (first connection switching unit)
38 Comparator 39 Input Terminal 40 First External Output Terminal 41 Second External Output Terminal 42 Ground Terminal 43 Second Switch Circuits 46 and 47 Latch Circuit 48 Third Switch Circuit 53 Clock Circuit 62 Antiferromagnetic Layer 63 Pinned Magnetic Layer 64 Nonmagnetic Intermediate layer 65, 67 Free magnetic layer

Claims (3)

A magnet and a non-contact type magnetic sensor having a magnetoresistive effect element whose electric resistance value changes with respect to an external magnetic field, and one of the magnet and the magnetic sensor is supported by a rotating portion, and the other In the rotation detector supported by the fixed part,
At least two magnets and one magnetic sensor are used, and the rotating part is supported to be rotatable in the direction of gravity,
In the reference state, the magnetic sensor is arranged in the direction of gravity from the rotation center of the rotation unit, and the magnet is arranged at a position away from the rotation center on both the left and right sides of the magnetic sensor,
As the clockwise or counterclockwise rotation from the reference state, the rotating part rotates toward the gravitational direction and maintains a constant posture in the gravitational direction. At this time, relative to the magnet of the magnetic sensor As the position approaches, the magnetic sensor receives an external magnetic field from the magnet and the electric resistance value of the magnetoresistive effect element changes, and the rotation direction can be known from the output from the magnetic sensor based on this electric resistance change. A rotation detection device characterized by the above. The magnetoresistive element has a pinned magnetic layer and a free magnetic layer laminated on the pinned magnetic layer via a nonmagnetic layer, and the magnetization of the pinned magnetic layer is pinned in one direction,
In the reference state, one magnet has an external magnetic field parallel to the fixed magnetization direction of the fixed magnetic layer of the magnetoresistive element when the relative position to the magnetic sensor approaches, so that the other magnet 2. Each magnet is magnetized so that an external magnetic field antiparallel to the fixed magnetization direction of the fixed magnetic layer of the magnetoresistive element acts when the relative position to the magnetic sensor approaches. Rotation detection device. The magnetic sensor has a first magnetoresistive element using a magnetoresistive effect in which an electric resistance changes with respect to an external magnetic field in one direction, and an electric resistance with respect to an external magnetic field in a direction opposite to the one direction. A second magnetoresistive element utilizing a changing magnetoresistive effect, a first output terminal, and a second output terminal;
The signal based on the electrical resistance change of the first magnetoresistive effect element is output from the first output terminal, and the signal based on the electrical resistance change of the second magnetoresistive effect element is output from the second output terminal. The rotation detection device according to 1 or 2.

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