JP5139190B2 - Magnetic switch - Google Patents

Description

  The present invention particularly relates to a magnetic switch that can be reduced in size and reduced in manufacturing cost.

  A giant magnetoresistive element (GMR element) having a laminated structure of a pinned magnetic layer with a fixed magnetization direction, a nonmagnetic layer, and a free magnetic layer whose magnetization direction fluctuates with respect to an external magnetic field is detected with respect to the external magnetic field. Embedded in a magnetic switch for obtaining a signal.

  Conventionally, in order to detect the change in the magnetic field strength of the external magnetic field in the first direction and the change in the magnetic field strength of the external magnetic field in the second direction opposite to the first direction, respectively, Two types of GMR element and a GMR element for external magnetic field in the second direction are required. In addition, when a bridge circuit is assembled, two types of fixed resistance elements are required in accordance with the element characteristics (temperature characteristics, etc.) of each GMR element. That is, conventionally, four different types of elements are required.

  In addition, a control signal (integrated circuit) electrically connected to a circuit including a GMR element or a fixed resistance element generates and outputs a detection signal based on a sensor output that changes based on a change in electric resistance of the first GMR element. Therefore, two systems of a first electric circuit for generating and a second electric circuit for generating and outputting a detection signal by a sensor output that changes based on a change in electric resistance of the second GMR element are required.

  As described above, in the conventional magnetic switch for bipolar detection, two types of GMR elements are required, and when combined with the fixed resistance, four types of elements are required. Therefore, the material cost for manufacturing the element (manufacturing cost) is increased. . In addition, since the control unit also requires two electric circuits, the chip size becomes large, and there is a problem that the miniaturization of the magnetic switch cannot be promoted.

Patent Documents 1 and 2 do not recognize the conventional problems of the magnetic switch described above, and naturally, no solution is shown.
JP 2002-319112 A JP 2004-14610 A

  Accordingly, the present invention is to solve the above-described conventional problems, and in particular, to provide a magnetic switch for bipolar detection that can suffice with one kind of magnetic detection element and that can be configured with a common circuit as a control unit. It is said.

The present invention provides a magnetic detection element whose electric resistance value changes with respect to an external magnetic field from the sensitivity axis direction, and a control unit that outputs a detection signal based on a sensor output that changes based on a change in electric resistance of the magnetic detection element. In a magnetic switch comprising:
One kind of the magnetic detection element is built in, and the magnetic detection element includes an element portion in which a first magnetic layer and a second magnetic layer that can change magnetization with respect to an external magnetic field are stacked via a nonmagnetic layer. provided, the first direction of the sensitivity axis direction, and with respect to the magnetic field strength change of the second direction of the external magnetic field of said first direction backward, respectively, in the configuration electric resistance value varies Yes,
In the common circuit, each of the control units is based on the sensor outputs obtained by the magnetic field strength change of the external magnetic field from the first direction and the magnetic field strength change of the external magnetic field from the second direction. It can output detection signals ,
The element portion is formed in an elongated shape having the sensitivity axis direction as a longitudinal direction,
In the absence of a magnetic field, the magnetization direction of the first magnetic layer is inclined in the first direction from the element width direction orthogonal to the sensitivity axis direction, and the magnetization direction of the second magnetic layer is changed from the element width direction. Inclined in the second direction, the magnetization direction of the first magnetic layer and the magnetization direction of the second magnetic layer are substantially anti-parallel toward a direction parallel to the sensitivity axis direction. To do.

  The magnetic switch of the present invention is a bipolar detection compatible type. That is, when an external magnetic field in the first direction acts, the external magnetic field in the first direction is detected and a detection signal (ON signal) is output, and the external in the second direction opposite to the first direction. When a magnetic field is applied, an external magnetic field in the second direction is detected and a detection signal (ON signal) is output.

  In the present invention, the magnetic detection element including the first magnetic layer and the second magnetic layer that can change the magnetization with respect to the external magnetic field is used in the above-described magnetic switch for bipolar detection. This magnetic detection element varies in electrical resistance value with respect to an external magnetic field from the first direction and an external magnetic field from the second direction. Therefore, in the present invention, bipolar detection is possible by incorporating such one type of magnetic detection element into the sensor unit. And the control part which is electrically connected with the said magnetic detection element, and produces | generates and outputs a detection signal can be comprised by a common circuit (1 system | strain).

  As described above, according to the magnetic switch for bipolar detection according to the present invention, the manufacturing cost can be reduced, and further, the size can be reduced.

Further, according to the present invention, it is possible to provide a good magnetic sensitivity with respect to an external magnetic field from the sensitivity axis direction, and to improve disturbance resistance against a magnetic field from a direction different from the sensitivity axis direction.

  In the present invention, a magnetic detection element including a first magnetic layer and a second magnetic layer that can change magnetization with respect to an external magnetic field is used in a magnetic switch that supports bipolar detection. The magnetic detection element varies in electrical resistance value with respect to an external magnetic field from the first direction and an external magnetic field from the second direction (the direction opposite to the first direction). Therefore, in the present invention, bipolar detection is possible by incorporating such one type of magnetic detection element into the sensor unit. And the control part which is electrically connected with the said magnetic detection element, and produces | generates and outputs a detection signal can be comprised by a common circuit (1 system | strain).

  As described above, according to the magnetic switch for bipolar detection according to the present invention, the manufacturing cost can be reduced, and further, the size can be reduced.

  FIG. 1 is an enlarged plan view of a magnetic detection element incorporated in a magnetic switch, FIG. 2 is a partially enlarged cross-sectional view of the magnetic detection element shown in FIG. FIG. 4 is a schematic diagram showing the magnetization relationship between the first magnetic layer and the second magnetic layer in a plan view, FIG. 4 is a graph showing the relationship between the external magnetic field and the electric resistance value of the magnetic detection element in the present embodiment, and FIG. 6 is a circuit diagram of the magnetic switch of the present embodiment, FIG. 6 is a graph showing the relationship between the external magnetic field and the sensor output (voltage value) of the magnetic switch of the present embodiment, and FIG. 7 is a state in which the folding cellular phone is opened. FIG. 8 is a perspective view of the foldable mobile phone shown in FIG. 7, FIG. 9 is a side view of the foldable mobile phone showing a state in the middle of closing the foldable mobile phone from the state of FIG. From the side of the closed state of the completely folding mobile phone from the state of FIG. FIG. 11 is a partial cross-sectional view of the closed folding cellular phone shown in FIG. 10 taken along the line BB and viewed from the direction of the arrow, and FIG. 12 is an inverted view of the display housing from the state of FIG. FIG. 13 is a plan view of the foldable mobile phone showing a state in which the front and back surfaces of the display housing are reversed.

  Each direction of the X1-X2 direction, the Y1-Y2 direction, and the Z1-Z2 direction in each figure has a relationship orthogonal to the remaining two directions.

  The magnetic switch 22 of this embodiment is a magnetic sensor capable of detecting bipolar. For example, as shown in FIG. 7, the magnetic switch 22 is built in the folding cellular phone 1.

  As shown in FIG. 7, the foldable mobile phone 1 includes a display housing 2, an operation housing 3, and a hinge portion 4 that connects the display housing 2 and the operation housing 3.

  When the foldable mobile phone 1 is opened as shown in FIG. 7, a display surface 2 a provided with a display screen 5 such as a liquid crystal display of the display housing 2 and various operation buttons 6 of the operation housing 3 are arranged. The operation surface 3a is directed to the same side.

  A speaker 45 is provided on the display surface 2 a of the display housing 2, and a microphone 7 is provided on the operation surface 3 a of the operation housing 3.

  As shown in FIG. 8, the hinge part 4 is provided with a first rotating shaft 50 extending in the lateral direction (Y1-Y2 direction in the drawing). The display housing 2 is configured to rotate in the opening / closing direction about the first rotation shaft 50 with respect to the operation housing 3.

  Further, as shown in FIG. 8, the hinge portion 4 has a direction orthogonal to the first rotation shaft 50 (X1-X2 direction in the drawing) and a lateral direction of the hinge portion 4 (Y1-Y2 direction in the drawing). A second rotation shaft 56 is provided at the center, and the display housing 2 is connected to the second rotation shaft 56. The display housing 2 is supported so as to be reversible around the second rotation shaft 56. Therefore, in the foldable mobile phone 1 of this embodiment, the front and back surfaces of the display housing 2 can be reversed as shown in FIG. 12 from the normal use state of FIG. 8 to shift to the reversed state shown in FIG.

  As shown in FIG. 7, the magnetic switch 22 is built in the operation housing 3 and the magnet 53 is built in the display housing 2. The arrangement may be reversed.

  For example, as shown in FIG. 7, the magnet 53 is arranged such that the N pole and the S pole face in the horizontal direction (Y1-Y2 direction in the drawing).

  In this embodiment, the magnetic switch 22 is disposed at a position facing the magnet 53 in the height direction (Z direction in the drawing) when the display housing 2 and the operation housing 3 are closed as shown in FIG. The Alternatively, the magnetic switch 22 may be arranged at a position shifted in the Y1-Y2 direction with respect to the magnet 53.

  The magnetic field strength of the external magnetic field H acting on the magnetic switch 22 from the magnet 53 gradually increases until the foldable mobile phone 1 is closed as shown in FIG. As shown in FIG. 11, in the closed state, an external magnetic field H directed in the Y1 direction acts on the magnetic switch 22.

  When the folding cellular phone 1 is opened from the closed state of FIG. 10 as shown in FIG. 9, the magnetic field strength of the external magnetic field H acting on the magnetic switch 22 gradually decreases. Then, as shown in FIG. 12, when the front and back surfaces of the display housing 2 are reversed and the foldable mobile phone 1 is closed again from the state of FIG. 13, the magnetic switch 22 receives the external magnetic field H from the magnet 53. This time, unlike FIG. 11, an external magnetic field H directed in the Y2 direction acts on the magnetic switch 22.

The configuration of the magnetic switch 22 of this embodiment will be described.
As shown in FIGS. 1 and 5, the magnetic switch 22 incorporates one type of magnetic detection element A1.

  As shown in FIG. 1, the magnetic detection element A1 includes an element portion 10 that extends in a band shape in the Y1-Y2 direction. The element width in the X1-X2 direction of the element part 10 is formed by W1, and the length dimension in the Y1-Y2 direction of the element part 10 is formed by L1. As shown in FIG. 1, the length dimension L1 is larger than the element width W1. Therefore, the element portion 10 is formed in an elongated shape with the Y1-Y2 direction as the longitudinal direction.

  As shown in FIG. 1, a plurality of element units 10 are provided, and each element unit 10 is arranged in parallel at a predetermined interval T1 in the X1-X2 direction.

  As shown in FIG. 1, the end portions in the Y1-Y2 direction of each element unit 10 are connected by a connection unit 11. The connection portion 11 is formed of an electrode layer made of a nonmagnetic conductive material, or is formed of a hard bias layer or the like. The magnetic detection element A <b> 1 is formed in a meander shape by the element part 10 and the connection part 11. The connection portion 11 may be formed in the same layer configuration as the element portion 10 and may have a meander shape integrated with the layer configuration of the element portion 10. Even when the connection part 11 is formed in the same layer configuration as the element part 10, the length dimension L1 of the element part 10 is defined excluding the part of the connection part 11 (matching the length dimension L1 in FIG. 2).

  As shown in FIG. 1, a wiring pattern portion 12 made of a nonmagnetic conductive material is connected to the end portions of the element portion 10 located on both sides in the X1-X2 direction.

  The element unit 10 is formed on the substrate 23 with a multilayer structure shown in FIG. As shown in FIG. 2, the element part 10 is laminated | stacked in order of the seed layer 30, the 1st magnetic layer 31, the nonmagnetic layer 32, the 2nd magnetic layer 33, and the protective layer 34 from the bottom. The seed layer 30 is formed of NiFeCr or Cr. The seed layer 30 is a layer provided for adjusting the crystal orientation of each layer formed thereon. The seed layer 30 may not be formed. A nonmagnetic underlayer made of Ta or the like may be formed under the seed layer 30. In the case where the seed layer 30 is not formed, it is preferable to form the first magnetic layer 31 on the substrate 23 via an underlayer.

  The first magnetic layer 31 is laminated in order of the Ni—Fe layer 35 and the Co—Fe layer 36 from the bottom.

  The nonmagnetic layer 32 is preferably formed of one or more alloys of Cu, Ru, Rh, Ir, Cr, and Re.

  The second magnetic layer 33 is laminated in order of a Co—Fe layer 37 and a Ni—Fe layer 38 from the bottom.

  The protective layer 34 is made of Ta, for example. The formation of the protective layer 34 is not essential, but it is better to form it.

  As shown in FIG. 2, the first magnetic layer 31 and the second magnetic layer 33 are laminated via a nonmagnetic layer 32. Both the first magnetic layer 31 and the second magnetic layer 33 have a laminated structure of Co—Fe layers 36 and 37 and Ni—Fe layers 35 and 38. As shown in FIG. 2, the Co—Fe layer 36 constituting the first magnetic layer 31 and the Co—Fe layer 37 constituting the second magnetic layer 33 are opposed to each other with the nonmagnetic layer 32 interposed therebetween.

  Both the first magnetic layer 31 and the second magnetic layer 33 are preferably formed of the same magnetic material. Thereby, it is easy to adjust Ms · t (Ms is saturation magnetization and t is film thickness) of the first magnetic layer 31 and the second magnetic layer 33 described later.

  The first magnetic layer 31 and the second magnetic layer 33 may be formed of a magnetic material other than Ni—Fe or Co—Fe. Further, each of the magnetic layers 31 and 33 may have a single layer structure or a laminated structure.

  However, as shown in FIG. 2, each magnetic layer 31, 33 is formed by a laminated structure of Ni—Fe layers 35, 38 and Co—Fe layers 36, 37, and the Co—Fe layers 36, 37 are interposed via the nonmagnetic layer 32. Are preferably opposed to each other. Thereby, it is possible to suppress Ni—Fe from diffusing into the nonmagnetic layer 32 when heat is applied.

  Both the first magnetic layer 31 and the second magnetic layer 33 can change the magnetization with respect to an external magnetic field. That is, the magnetization is not fixed like the pinned magnetic layer of the GMR element.

In the present embodiment, the Y1-Y2 direction is the sensitivity axis direction of the magnetic detection element A1.
As shown in FIG. 3, in the non-magnetic state (state where no external magnetic field is applied), the magnetization direction F1 of the first magnetic layer 31 is perpendicular to the sensitivity axis direction (Y1-Y2 direction). It is inclined from the (X1-X2 direction) to the Y1 direction (first direction), and the magnetization direction F2 of the second magnetic layer 33 is changed from the element width direction (X1-X2 direction) to the Y2 direction (second direction). Tilted. The angle θ between the magnetization direction F1 of the first magnetic layer 31 and the magnetization direction F2 of the second magnetic layer 33 is in the range of 90 degrees to 180 degrees. The inclination θ1 of the magnetization direction F1 of the first magnetic layer 31 from the element width direction (X1-X2 direction) and the inclination θ2 of the magnetization direction F2 of the second magnetic layer 33 from the element width direction (X1-X2 direction). Are almost the same.

  As shown in FIG. 2, in the present embodiment, in the non-magnetic state, the magnetization direction F1 of the first magnetic layer 31 and the magnetization direction F2 of the second magnetic layer 33 are in the sensitivity axis direction (Y1-Y2 direction). ) Is preferably substantially antiparallel.

  Here, “substantially antiparallel” means that the angle θ (obtuse angle) between the magnetization direction F1 of the first magnetic layer 31 and the magnetization direction F2 of the second magnetic layer 33 is within a range of 150 degrees to 180 degrees.

  A coupling magnetic field is generated between the first magnetic layer 31 and the second magnetic layer 33 by the RKKY interaction. Therefore, after the element unit 10 shown in FIG. 2 is stacked, if the annealing process is performed while applying a magnetic field in either the Y1 direction or the Y2 direction, the magnetization directions F1 and F1 of the first magnetic layer 31 and the second magnetic layer 33 are once. Although F2 faces the same direction, when the annealing in the magnetic field is stopped, the magnetization direction F1 of the first magnetic layer 31 and the magnetization direction F2 of the second magnetic layer 33 tend to be antiparallel due to the coupling magnetic field due to the RKKY interaction.

  FIG. 4 is a graph showing resistance values when an external magnetic field is applied in the Y1-Y2 direction (sensitivity axis direction) to the magnetic detection element A1 of the present embodiment. FIG. 4 shows resistance values within a range of −100 Oe to +100 Oe.

  The magnetic detection element A1 used in the experiment shown in FIG. 4 has an angle θ between the magnetization direction F1 of the first magnetic layer 31 and the magnetization direction F2 of the second magnetic layer 33 in the absence of a magnetic field (external magnetic field is 0 Oe). (Obtuse angle) is about 170 degrees.

  When the magnetic field strength of the external magnetic field H is increased in the Y1 direction from the no magnetic field state (external magnetic field is 0 Oe) shown in FIG. 3, the magnetization of the first magnetic layer 31 is caused by the external magnetic field and the coupling magnetic field due to the RKKY interaction. The direction F1 and the magnetization direction F2 of the second magnetic layer 33 are antiparallel or closer to antiparallel, and the resistance value is increased (the maximum value is obtained when antiparallel). In the absence of a magnetic field, if the magnetization direction F1 of the first magnetic layer 31 and the magnetization direction F2 of the second magnetic layer 33 are antiparallel, the phenomenon that the resistance value temporarily increases does not occur.

  When the external magnetic field is further increased in the Y1 direction, the antiparallel state is lost, and the magnetization direction F2 of the second magnetic layer 33 rotates from the Y2 direction to the Y1 direction. Therefore, the magnetization direction F1 of the first magnetic layer 31 and the magnetization direction F2 of the second magnetic layer 33 approach a parallel state, and the resistance value gradually decreases.

  On the other hand, when the external magnetic field is increased in the Y2 direction from the no magnetic field state (external magnetic field is 0 Oe) shown in FIG. 3, the magnetization direction F1 of the first magnetic layer 31 is generated by the external magnetic field and the coupling magnetic field due to the RKKY interaction. And the magnetization direction F2 of the second magnetic layer 33 are antiparallel or close to antiparallel, and the resistance value becomes larger (the antimagnetic value becomes the maximum value). When the external magnetic field is further increased in the Y2 direction, the antiparallel state is lost, and the magnetization direction F1 of the first magnetic layer 31 rotates from the Y1 direction to the Y2 direction. Therefore, the magnetization direction F1 of the first magnetic layer 31 and the magnetization direction F2 of the second magnetic layer 33 approach a parallel state, and the resistance value gradually decreases.

  As shown in FIG. 4, hysteresis occurs in the RH curve. Therefore, it can be seen that the first magnetic layer 31 and the second magnetic layer 33 have a coercive force (Hc).

  Further, as shown in FIG. 4, the resistance value change waveform when the external magnetic field H is applied in the Y1 direction with the line having the external magnetic field of 0 Oe as the axis of symmetry and when the external magnetic field H is applied in the Y2 direction. Is substantially symmetrical. Therefore, the magnetic sensitivities to the external magnetic field H from the Y1 direction and the external magnetic field H from the Y2 direction are substantially the same. In order to adjust the magnetic sensitivity to substantially the same with respect to the external magnetic field H from the Y1 direction and the Y2 direction in this way, the Ms1 · t1 (Ms is saturation magnetization and t is the film thickness) of the first magnetic layer 31 and the second It is preferable to reduce the ratio of Ms 2 · t 2 of the magnetic layer 33. For example, in this embodiment, (Ms 2 · t 2 / Ms 1 · t 1) is larger than 1 and smaller than 2.

  However, the magnetic sensitivity to the external magnetic field H from the Y1 direction may be adjusted to be different from the magnetic sensitivity H to the external magnetic field from the Y2 direction. For example, when the magnetic switch 22 is built in the folding cellular phone 1, the distance D1 (see FIG. 11) between the magnetic switch 22 and the magnet 53 when the folding cellular phone 1 is closed from the normal use state of FIG. The distance between the magnetic switch 22 and the magnet 53 when the foldable mobile phone 1 is closed from the state in which the front and back surfaces of the display housing 2 in FIG. 13 are inverted may be different. In such a case, in order to obtain a detection signal (ON signal) at the same timing between the two, adjustment is made by making the magnetic sensitivity to the external magnetic field H from the Y1 direction different from the magnetic sensitivity to the external magnetic field H from the Y2 direction. Can do. For example, the inclination θ1 of the magnetization direction F1 of the first magnetic layer 31 and the inclination θ2 of the magnetization direction F2 of the second magnetic layer 33 in the no magnetic field state shown in FIG. And the magnetic sensitivity to the external magnetic field H from the Y2 direction can be adjusted to be different.

  Moreover, in this embodiment, the element part 10 which comprises a magnetic detection element is formed in the elongate shape which made the Y1-Y2 direction (sensitivity axis direction) a longitudinal direction. Therefore, the Y1-Y2 direction of the element portion 10 is the easy axis direction due to the shape magnetic anisotropy. Therefore, even if an external magnetic field (disturbance magnetic field) acts in the X1-X2 direction orthogonal to the Y1-Y2 direction, the resistance of the magnetic detection element hardly changes, and the disturbance tolerance can be improved.

  As shown in FIG. 5, the magnetic switch 22 includes a sensor unit 15 including the magnetic detection element A <b> 1 and a control unit for generating and outputting an on / off binary signal based on the sensor output from the sensor unit 15. And an integrated circuit (IC) 16.

  As shown in FIG. 5, in the sensor unit 15, one magnetic detection element A <b> 1 and one fixed resistance element 17 constitute a series circuit. In addition, two fixed resistance elements 17 connected in series are provided in the control unit 16 and together form a bridge circuit.

  In the present embodiment, only one type of magnetic detection element A1 is incorporated in the bridge circuit. If there is one type, even if only one magnetic detection element 1 is arranged as shown in FIG. 5, a plurality of the same magnetic detection elements A1 may be incorporated in the bridge circuit. Further, only one type of fixed resistance element 17 is sufficient to match the element characteristics such as temperature characteristics of the magnetic detection element A1.

  As shown in FIG. 5, the bridge circuit is connected to an input terminal 24, a ground terminal 25, and a differential amplifier 18 provided in the control unit 16.

  The differential output obtained from the differential amplifier 18 based on the change in the electric resistance value of the magnetic detection element A1 is sent to a comparator (comparing circuit) 19 having a threshold value, and the waveform is shaped as shown in FIG. As shown in FIG. 6, when the magnetic field strength of the external magnetic field H increases and the external magnetic field becomes Hon, the sensor output whose waveform is shaped changes from the high level (V Hi) to the low level (V Lo) and is detected. A signal (ON signal) is output. On the other hand, when the magnetic field strength of the external magnetic field H becomes weak and the external magnetic field becomes Hoff, the sensor output whose waveform is shaped changes from low level (V Lo) to high level (V Hi), and an off signal is output ( No ON signal is output).

  As shown in FIG. 5, a latch circuit 20 is connected to the output side of the comparator 19, and an output terminal 21 is connected to the output side of the latch circuit 20. Since the latch circuit 20 is provided, when the ON signal is output, the ON signal is continuously output unless it is detected that the sensor output has become high level. When the off signal is output, the off signal continues to be output unless it is detected that the sensor output has become low level. Further, as shown in FIG. 5, the control unit 16 includes a clock circuit 26 and a switch circuit 27. In the circuit configuration of FIG. 5, when the switch circuit 27 is turned off, the energization from the input terminal 24 to the bridge circuit is stopped. The on / off of the switch of the switch circuit 27 is interlocked with the clock signal from the clock circuit 26, and the switch circuit 27 has a power saving function for intermittently conducting the energized state.

  Consider the folding cellular phone 1 shown in FIG. First, in the normal use state shown in FIG. 7, the magnetic switch 22 is separated from the magnet 53 by a distance, and the external magnetic field H does not act on the magnetic switch 22 from the magnet 53. That is, there is no magnetic field. Therefore, the sensor output is at the high level shown in FIG. 6, and an off signal is output from the output terminal 21 (an on signal is not output).

  When shifting from the open state of FIG. 7 to the state of FIG. 9 and further closing as shown in FIG. 10, the magnetic field strength of the external magnetic field H from the magnet 53 acting on the magnetic switch 22 toward the Y1 direction gradually increases. Then, the substantially antiparallel state of the magnetization directions F1 and F2 of the first magnetic layer 31 and the second magnetic layer 33 of the magnetic detection element A1 collapses, and the electrical resistance value gradually decreases as shown in FIG. As shown in FIG. 6, when the external magnetic field H becomes equal to or higher than the magnetic field strength Hon, the sensor output shifts from the high level to the low level, and a detection signal (ON signal) is output from the output terminal 21.

  Next, when the closed state in FIG. 10 is shifted to the open state in FIG. 7, when the external magnetic field H becomes lower than the magnetic field strength Hoff, the sensor output shifts from the low level to the high level and an off signal is output. The Since hysteresis occurs in the sensor output as shown in FIG. 6, the timing at which an ON signal is generated when the state of FIG. 7 is shifted to the state of FIG. 10, and the state of FIG. 10 to the state of FIG. There is a deviation from the timing at which the off signal is generated when the shift to. Such timing shift can contribute to suppression of chattering.

  From the state of FIG. 7, the front and back surfaces of the display housing 2 are reversed as shown in FIG. 12, and the foldable mobile phone 1 is closed from the open state of the state of FIG. Then, the external magnetic field H from the Y2 direction acts on the magnetic switch 22, and the magnetic field strength of the external magnetic field H gradually increases.

  Thereby, the substantially antiparallel state of the magnetization directions F1 and F2 of the first magnetic layer 31 and the second magnetic layer 33 of the magnetic detection element A1 collapses, and the electrical resistance value gradually decreases as shown in FIG. As shown in FIG. 6, when the external magnetic field H in the Y2 direction becomes greater than or equal to the magnetic field strength Hon, the sensor output shifts from the high level to the low level, and the detection signal (ON signal) is output from the output terminal 21. The

Hereinafter, a characteristic configuration of the magnetic switch 22 of the present embodiment will be described.
One type of magnetic detection element A1 is disposed in the sensor unit 15 (see FIG. 5). The magnetic detection element A1 has a configuration in which a first magnetic layer 31 and a second magnetic layer 33 that can change magnetization with respect to an external magnetic field H are stacked via a nonmagnetic layer 32 (see FIG. 2). In the magnetic detection element A1, the electric resistance value fluctuates with respect to a change in the magnetic field strength of the external magnetic field H from both directions with respect to the sensitivity axis direction (Y1-Y2 direction) (see FIG. 4). As shown in FIG. 4, the electric resistance value with respect to the magnetic field strength change of the external magnetic field in the Y1 direction and the electric resistance value with respect to the magnetic field strength change of the external magnetic field H in the Y2 direction fluctuate in the same tendency. That is, as the magnetic field strength of the external magnetic field H in the Y1 direction and the Y2 direction increases, the electrical resistance value decreases in the same manner. As the magnetic field strength of the external magnetic field in the Y1 direction and Y2 direction decreases, the electrical resistance value decreases. Each rises in the same way. Thus, in order to change the electric resistance value with respect to the magnetic field strength change of the external magnetic field H in the Y1 direction and the electric resistance value with respect to the magnetic field strength change of the external magnetic field H in the Y2 direction in the same tendency, The magnetization direction F1 of the magnetic layer 31 is inclined from the element width direction (X1-X2 direction) orthogonal to the sensitivity axis direction to the first direction (Y1 direction in FIG. 4) in the sensitivity axis direction (Y1-Y2 direction). The magnetization direction F2 of the second magnetic layer 33 may be controlled to be inclined from the element width direction to a second direction (Y2 direction in FIG. 4) opposite to the first direction in the sensitivity axis direction.

  In this embodiment, the angle θ between the magnetization direction F1 of the first magnetic layer 31 and the magnetization direction F2 of the second magnetic layer 33 is preferably in the range of 90 degrees to 180 degrees. More preferably, the magnetization direction F1 of the first magnetic layer 31 and the magnetization direction F2 of the second magnetic layer 33 are substantially antiparallel. Furthermore, in this embodiment, as shown in FIG. 1, it is preferable that each element unit 10 is formed in an elongated shape with the sensitivity axis direction (Y1-Y2 direction) as the longitudinal direction. As a result, it is possible to improve the disturbance resistance against a magnetic field from a direction different from the sensitivity axis direction while providing good magnetic sensitivity to the external magnetic field H from the sensitivity axis direction.

  In this manner, if the magnetic detection element A1 in the present embodiment is incorporated in the sensor unit 15, bipolar detection is possible.

  In this embodiment, as shown in FIGS. 5 and 6, the control unit 16 uses a common circuit to change the magnetic field strength of the external magnetic field H from the Y1 direction and change the magnetic field strength of the external magnetic field H from the Y2 direction. Each detection signal (ON signal) can be output based on each sensor output obtained by the above.

  As shown in FIG. 5, there is one bridge circuit, and only one main signal line from the bridge circuit to the output terminal 21 is required. That is, unlike the prior art, two systems of an electric circuit for an external magnetic field in the Y1 direction and an electric circuit for an external magnetic field in the Y2 direction are not required. Therefore, the control unit 16 can be reduced in size.

  As described above, according to the magnetic switch 22 for bipolar detection in the present embodiment, the manufacturing cost can be reduced, and further downsizing can be realized.

  Although the foldable mobile phone 1 has been described as an example of the use of the magnetic switch 22, it is naturally not limited to this. There are two housings with varying distances. One housing includes a magnetic switch 22 and the other housing includes a magnet 53. The magnetic switch 22 is separated from the magnet 53 by a variation in the distance between the housings. It is preferably used for an application for detecting an external magnetic field. Although the above-described foldable mobile phone 1 is an application that requires bipolar detection, it is not necessarily limited to an application that requires bipolar detection. For example, this embodiment can be preferably applied to the folding cellular phone 1 that cannot perform the reversing operation shown in FIGS. In such a case, only the external magnetic field H in one direction is detected. However, for example, even if the magnetic detection element A1 shown in FIG. The external magnetic field H can be detected. That is, if the magnetic switch 22 of this embodiment is used, the freedom degree of arrangement | positioning (direction) of a magnetic switch (magnetic detection element) can be improved. In the case of such use, as shown in FIG. 3, the inclination θ1 of the magnetization direction F1 of the first magnetic layer 31 from the element width direction (X1-X2 direction) and the element of the magnetization direction F2 of the second magnetic layer 33 are shown. The inclination θ2 from the width direction (X1-X2 direction) is substantially the same, and the magnetic sensitivity to the external magnetic field H from the sensitivity axis direction in the Y1 direction and the magnetic sensitivity to the external magnetic field H from the sensitivity axis direction in the Y2 direction are approximately the same. It is preferable to adjust the same.

An enlarged plan view of a magnetic detection element incorporated in the magnetic switch, FIG. 1 is a partially enlarged cross-sectional view of the magnetic sensing element shown in FIG. The schematic diagram which looked at the magnetization relationship of a 1st magnetic layer and a 2nd magnetic layer planarly, A graph showing the relationship between the external magnetic field and the electrical resistance value of the magnetic sensing element in the present embodiment; The circuit diagram of the magnetic switch of this embodiment, A graph showing the relationship between the external magnetic field and the sensor output (voltage value) of the magnetic switch in the present embodiment; A plan view of a state in which the folding mobile phone is opened, FIG. 7 is a perspective view of the folding mobile phone shown in FIG. The side view of a foldable mobile phone which shows the state in the middle of closing a foldable mobile phone from the state of FIG. The side view which looked at the closed state of a completely folding cellular phone from the state of FIG. The fragmentary sectional view which cut | disconnected the foldable mobile telephone of the closed state shown in FIG. 10 from the BB line, and was seen from the arrow direction, FIG. 9 is a perspective view of a folding mobile phone showing a state in the middle of reversing the display housing from the state of FIG. A plan view of a foldable mobile phone showing a state in which the front and back surfaces of the display housing are reversed,

Explanation of symbols

A1 Magnetic detection element H External magnetic field 1 Folding mobile phone 2 Display case 3 Operation case 4 Hinge part 10 Element part 15 Sensor part 16 Control part 17 Fixed resistance element 18 Differential amplifier 19 Comparator 20 Latch circuit 21 Output terminal 22 Magnetism Switch 24 Input terminal 25 Ground terminal 31 First magnetic layer 32 Nonmagnetic layer 33 Second magnetic layer 50 First rotating shaft 53 Magnet 56 Second rotating shaft

Claims (1)

A magnetic detection element whose electric resistance value changes with respect to an external magnetic field from the sensitivity axis direction; and a control unit which outputs a detection signal based on a sensor output which changes based on a change in electric resistance of the magnetic detection element. In the magnetic switch consisting of
One kind of the magnetic detection element is built in, and the magnetic detection element includes an element portion in which a first magnetic layer and a second magnetic layer that can change magnetization with respect to an external magnetic field are stacked via a nonmagnetic layer. provided, the first direction of the sensitivity axis direction, and with respect to the magnetic field strength change of the second direction of the external magnetic field of said first direction backward, respectively, in the configuration electric resistance value varies Yes,
In the common circuit, each of the control units is based on the sensor outputs obtained by the magnetic field strength change of the external magnetic field from the first direction and the magnetic field strength change of the external magnetic field from the second direction. It can output detection signals ,
The element portion is formed in an elongated shape having the sensitivity axis direction as a longitudinal direction,
In the absence of a magnetic field, the magnetization direction of the first magnetic layer is inclined in the first direction from the element width direction orthogonal to the sensitivity axis direction, and the magnetization direction of the second magnetic layer is changed from the element width direction. Inclined in the second direction, the magnetization direction of the first magnetic layer and the magnetization direction of the second magnetic layer are substantially anti-parallel toward a direction parallel to the sensitivity axis direction. Magnetic switch for bipolar detection.

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