Rotation angle detection device and folding machine equipped therewith

Abstract

The present invention provides a rotation angle detection device that is mounted on a folding machine comprising a first member and a second member rotatably supported by the first member, and that can detect the rotation angle of the second member regardless of the orientation of the folding machine. [Solution] The rotation angle detection device includes a magnet 21 attached to one of a first member 2 and a second member 3 rotatably supported by the first member 2, and a magnetic sensor 31 attached to the other. The first member 2 has a first rotation axis 6 extending in the Z direction, and the second member 3 has a second rotation axis 7 parallel to the first rotation axis 6. The second member 3 rotates around the first rotation axis 6 over a first angle section K1 and around the second rotation axis 7 over a second angle section K2 continuous with the first angle section K1. The magnetic sensor 31 detects the direction of the magnetic field in a plane perpendicular to the Z direction. The magnetic sensor 31 is located away from the center of the magnet 21 in the Z direction.

Description

Technical Field

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[0001] The present disclosure relates to a rotation angle detection device and a folding machine provided with the same.

Background Art

[0002] In recent years, in a personal computer (hereinafter referred to as a PC), a mechanism in which a display unit can rotate 360° with respect to a PC main body unit may be adopted. Patent Document 1 describes a PC in which a gravity sensor is mounted on each of a display unit and a PC main body unit. The rotation angle of the display unit with respect to the PC main body unit can be obtained from the outputs of the two gravity sensors.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Such a gravity sensor may not function accurately depending on the posture of the PC. For example, when the display unit is rotated with the rotation axis of the display unit with respect to the PC main body unit in the vertical direction, the gravity does not change, so the rotation angle cannot be detected. The same problem also exists in a folding machine including a first member and a second member rotatably supported by the first member.

[0005] An object of the present disclosure is to provide a rotation angle detection device mounted on a folding machine including a first member and a second member rotatably supported by the first member, capable of detecting the rotation angle of the second member regardless of the posture of the folding machine.

Means for Solving the Problems

[0006] The rotation angle detection device of this disclosure includes a magnet attached to one of a first member and a second member rotatably supported by the first member, and a magnetic sensor attached to the other member. The first member has a first axis of rotation extending in a first direction, and the second member has a second axis of rotation parallel to the first axis of rotation, and the second member rotates around the first axis of rotation over a first angular interval and over a second angular interval continuous with the first axis of rotation. The magnetic sensor detects the direction of the magnetic field in a plane perpendicular to the first direction. The magnetic sensor is located away from the center of the magnet in the first direction. [Effects of the Invention]

[0007] According to this disclosure, a rotation angle detection device can be provided that is mounted on a folding machine comprising a first member and a second member rotatably supported by the first member, and that can detect the rotation angle of the second member regardless of the orientation of the folding machine. [Brief explanation of the drawing]

[0008] [Figure 1] This is a side view of a PC (folding machine) according to the first embodiment of the present disclosure. [Figure 2] This is a schematic diagram showing how the display unit and the magnetic sensor rotate in the first embodiment of the present disclosure. [Figure 3] This is a schematic diagram of a rotation angle detection device according to the first embodiment of the present disclosure. [Figure 4] This is a schematic diagram showing the relationship between the rotation angle of the display unit and the magnetic field, and the relationship between the rotation angle of the display unit and the direction of the magnetic field, in the first embodiment of the present disclosure. [Figure 5] This is a top view of the magnet and magnetic sensor. [Figure 6] This is a schematic diagram showing how the display unit and the magnet rotate in a second embodiment of the present disclosure. [Figure 7] This is a schematic diagram showing the relationship between the rotation angle of the display unit and the magnetic field, and the relationship between the rotation angle of the display unit and the direction of the magnetic field, in a second embodiment of the present disclosure. [Figure 8] This is a schematic diagram showing the relationship between the rotation angle of the display unit and the magnetic field, and the relationship between the rotation angle of the display unit and the direction of the magnetic field, in a third embodiment of the present disclosure. [Figure 9] This is a schematic diagram of the angle sensor configuration. [Figure 10] This is a schematic diagram showing a modified example of a rotation angle detection device. [Modes for carrying out the invention]

[0009] Several embodiments of the present disclosure will be described with reference to the drawings. In the following description and drawings, the first direction is the direction in which the first and second rotation axes 6 and 7 extend, and is referred to as the Z direction. Since the magnet 21 and the magnetic sensor 31 move relative to each other, a coordinate system is defined for the magnet 21 and the magnetic sensor 31, respectively. In the coordinate system of the magnet 21, the two directions that are orthogonal to the Z direction and mutually orthogonal are called the MX direction and the MY direction. In the coordinate system of the magnetic sensor 31, the two directions that are orthogonal to the Z direction and mutually orthogonal are called the SX direction and the SY direction. The Z direction (Z axis) is common to both coordinate systems. Therefore, the coordinate system of the magnet 21 is the MX-MY-Z coordinate system, and the coordinate system of the magnetic sensor 31 is the SX-SY-Z coordinate system.

[0010] (First embodiment) Figure 1 is a side view of a personal computer (PC) 1 according to a first embodiment of the present disclosure. The PC 1 comprises a PC body 2 (an example of a first component) equipped with an operating unit 4 such as a keyboard, and a display unit 3 (an example of a second component) equipped with a display panel 5. The display panel 5 is a panel such as an organic EL or liquid crystal, and may have a touch panel function. The display unit 3 is rotatably supported by the PC body 2. The PC body 2 has a first rotation axis 6 extending in the Z direction, and the display unit 3 has a second rotation axis 7 extending in the Z direction and parallel to the first rotation axis 6 (i.e., away from the first rotation axis 6). The first rotation axis 6 and the second rotation axis 7 are rod-shaped members and are fixed to the PC body 2 and the display unit 3, respectively. When viewed from a direction perpendicular to the operating unit 4 of the PC body 2, the first rotation axis 6 and the second rotation axis 7 are in the same position. The PC 1 has a connecting member 8 that connects the first rotation axis 6 and the second rotation axis 7. PC1 is an example of a folding machine as described herein, and this disclosure is not limited to PC1.

[0011] The left column of Figure 2 shows the display unit 3 rotating 360° relative to the PC body unit 2. Here, the PC body unit 2 is fixed with the control unit 4 facing upwards, and the display unit 3 is rotated around the PC body unit 2. However, the PC body unit 2 may be rotated, or both the display unit 3 and the PC body unit 2 may be rotated. The black circle in the figure indicates the rotation center 9 of the display unit 3. The rotation center 9 changes during the rotation.

[0012] The rotation angle θ of the display unit 3 is defined as the direction in which the display unit 3 is opened, with the rotation angle of the display unit 3 being defined as 0° when the display unit 3 is closed. In the range of 0° ≤ θ ≤ 180°, the display unit 3 rotates around the first rotation axis 6 within the first angular interval K1, and the PC 1 can be used like a typical laptop. The display unit 3 rotates together with the connecting member 8 around the first rotation axis 6 of the PC body 2. In the range of 180° ≤ θ ≤ 360°, the display unit 3 rotates around the second rotation axis 7 within the second angular interval K2. When rotated 360°, the PC 1 can be used as a tablet. The connecting member 8 is fixed to the PC body 2, and the display unit 3 rotates around the connecting member 8. The first angular interval K1 and the second angular interval K2 are continuous and each spans an angular range of 180°. PC1 is equipped with a locking mechanism (not shown) that prevents the display unit 3 from rotating around the second rotation axis 7 in the first angular interval K1 and from rotating around the first rotation axis 6 in the second angular interval K2.

[0013] Figure 3(a) shows a schematic configuration diagram of the rotation angle detection device 11, and Figure 3(b) shows a schematic configuration diagram of the magnetic sensor 31. The PC1 has a rotation angle detection device 11 that detects the rotation angle θ of the display unit 3. The rotation angle detection device 11 includes a magnet 21 and a magnetic sensor 31 that detects the direction of the magnetic field generated by the magnet 21. The magnet 21 can be attached to either the PC body 2 or the display unit 3, and the magnetic sensor 31 can be attached to the other of the PC body 2 or the display unit 3. As shown in Figures 1 and 2, in this embodiment, the magnet 21 is attached to the PC body 2 and the magnetic sensor 31 is attached to the display unit 3. The magnet 21 is directly attached to the first rotation axis 6, but it may also be attached in the vicinity of the first rotation axis 6. The magnetic sensor 31 is directly attached to the second rotation axis 7, but it may also be attached in the vicinity of the second rotation axis 7. The magnet 21 is a rectangular parallelepiped with sides parallel to the MX, MY, and Z directions, and its dimension in the Z direction is larger than its dimensions in the MX and MY directions. The magnet 21 is magnetized in the MX direction, but it may also be magnetized in the MY direction.

[0014] As shown in Figure 3(b), the magnetic sensor 31 includes a first magnetic field detection unit 32 for detecting a magnetic field BZ in the Z direction, a second magnetic field detection unit 33 for detecting a magnetic field BX in the SX direction, and a third magnetic field detection unit 34 for detecting a magnetic field BY in the SY direction. The first magnetic field detection unit 32 can be configured as a full bridge and can be provided with a soft magnetic material (yoke) to change the direction of the magnetic field. The second magnetic field detection unit 33 and the third magnetic field detection unit 34 are each configured as half bridges, but can also be configured as full bridges. One end of the second magnetic field detection unit 33 and the third magnetic field detection unit 34 is connected to a power supply VDD and the other end is grounded (GND). The second magnetic field detection unit 33 has first and second parts 331 and 332 connected in series, and the third magnetic field detection unit 34 has third and fourth parts 341 and 342 connected in series. The first magnetic field detection unit 32, the first and second portions 331 and 332 of the second magnetic field detection unit 33, and the third and fourth portions 341 and 342 of the third magnetic field detection unit 34 are each equipped with magnetoresistive elements 38 as shown in Figure 3(c). The magnetization direction M1 of the magnetization fixed layer 383 of the first portion 331 and the magnetization direction M2 of the magnetization fixed layer 383 of the second portion 332 are oriented in opposite directions (with a 180° angle difference), and the magnetization direction M3 of the magnetization fixed layer 383 of the third portion 341 and the magnetization direction M4 of the magnetization fixed layer 383 of the fourth portion 342 are oriented in opposite directions (with a 180° angle difference). The magnetization directions M1, M2 and the magnetization directions M3, M4 are orthogonal.

[0015] FIG. 3(c) shows a schematic configuration of the magnetoresistive element 38. The magnetoresistive element 38 includes a magnetization-free layer 381 whose magnetization direction changes with respect to an external magnetic field, a magnetization-fixed layer 383 whose magnetization direction is fixed with respect to the external magnetic field, and a nonmagnetic layer 382 positioned between the magnetization-free layer 381 and the magnetization-fixed layer 383. The nonmagnetic layer 382 is made of an insulating layer such as MgO or Al2O3, and the magnetoresistive element 38 operates as a tunnel magnetoresistive element (TMR element). The nonmagnetic layer 382 may be made of a nonmagnetic metal layer such as copper or silver. In this case, the magnetoresistive element 38 operates as a giant magnetoresistive element (GMR element). The TMR element is more likely to obtain a higher output than the GMR element. The first to third magnetic field detection units 32 to 34 are formed on a single substrate 37, and the substrate 37 is mounted on the display unit 3 in a direction parallel to the SX-SY plane. The configurations of the first to third magnetic field detection units 32 to 34 are not limited as long as they can detect a magnetic field. For example, they may include an AMR element or a Hall element.

[0016] The right column of FIG. 2 shows how the magnet 21 and the magnetic sensor 31 move as the display unit 3 rotates. In the present embodiment, since the PC main body 2 is fixed, the magnet 21 maintains the same position and posture during the rotation of the display unit 3. Therefore, the magnetic field generated from the magnet 21 is also invariant regardless of the rotation angle θ of the display unit 3. On the other hand, since the magnetic sensor 31 is mounted on the display unit 3, the magnetic fields BZ, BX, and BY detected by the first to third magnetic field detection units 32 to 34 are functions of the rotation angle θ as described below. Since the magnetic sensor 31 rotates around the Z direction, the SX axis and the SY axis also rotate around the Z axis.

[0017] FIG. 4(a) shows the magnetic fields BZ, BX, and BY detected by the first to third magnetic field detection units 32 to 34. The dashed lines in the figure conceptually show the magnetic flux entering and leaving the magnet 21. The magnetic field BX changes in a sine wave form while the display unit 3 rotates 360°. In contrast, the magnetic field BY changes by half the wavelength of a sine wave while the display unit 3 rotates 180° in the first angular section K1, and changes by half the wavelength of a sine wave in the same direction as the first angular section K1 while rotating 180° in the second angular section K2. This is because due to the relative positional relationship between the third magnetic field detection unit 34 and the magnet 21, the magnetic field BY faces the same direction at θ = 90° and 270°. At θ = 90°, the magnetic sensor 31 faces the end (S pole) of the magnet 21, and at θ = 270°, the magnetic sensor 31 faces the side surface of the magnet 21. Therefore, the magnetic field BY in the first angular section K1 is larger than the magnetic field BY in the second angular section K2.

[0018] FIG. 5 shows a top view of the magnet 21 and the magnetic sensor 31 as seen from the MY direction. The dashed lines in the figure conceptually show the magnetic flux entering and leaving the magnet 21. At θ = 0°, the magnetic sensor 31 is at a position overlapping the symmetry axis (center line) of the magnet 21 as seen from the Z direction, that is, at the center of the magnet 21 in the MX direction. Therefore, at θ = 0°, due to the symmetry of the magnetic field, the magnetic field BZ = 0. While the magnetic sensor 31 rotates in the first angular section K1, the magnetic sensor 31 moves away from the center in the MX direction of the magnet 21, so the magnetic field BZ changes in a sine wave form. At θ = 180° (not shown in the figure but overlapping the position of θ = 0° in FIG. 5), the magnetic field BZ becomes zero again. In the second angular section K2, the magnetic sensor 31 rotates (spins) around the second rotation axis 7, and since the magnetic field in the Z direction hardly changes, the magnetic field BZ is almost zero. As can be seen from FIG. 5, at the center 22 of the magnet 21 in the Z direction, due to the symmetry of the magnetic field, BZ = 0 regardless of the rotation angle θ, and the rotation angle θ cannot be detected. Therefore, the magnetic sensor 31 is installed at a distance from the center 22 of the magnet 21 in the Z direction. However, the magnetic sensor 31 may be provided at a position overlapping the magnet 21 in the Z direction, or may be provided at a position away from the magnet 21.

[0019] As shown in Figure 3(b), the magnetic sensor 31 has a determination unit 35 that determines whether the display unit 3 is in a first angular interval K1 or a second angular interval K2 based on the magnetic field BZ. The determination unit 35 makes a determination based on whether the magnetic field BZ is greater than or less than a reference value. If the absolute value of the magnetic field BZ is greater than the reference value, the determination unit 35 determines that the display unit 3 is in the first angular interval K1, and if the absolute value of the magnetic field BZ is less than or equal to the reference value, the determination unit 35 determines that the display unit 3 is in the second angular interval K2. The reference value may be zero, but it may also be a value slightly greater than zero to account for signal errors. In an alternative embodiment, the determination may also be made considering the direction of the magnetic field. That is, if the strength (positive or negative sign) of the magnetic field BZ is greater than the reference value, the determination unit 35 may determine that the display unit 3 is in the first angular interval K1, and if the magnetic field BZ is less than or equal to the reference value, the determination unit 35 may determine that the display unit 3 is in the second angular interval K2. In the alternative embodiment, the magnetic field BY in the second angular interval K2 may take a value other than zero, so the magnetic sensor 31 may be offset from the center of the magnet 21 in the MX direction at θ=0° and 180°. This increases the degree of freedom in the installation position of the magnetic field sensor.

[0020] The magnetic sensor 31 has a calculation unit 36 ​​that detects (calculates) the direction of the magnetic field (magnetic field angle) in a plane perpendicular to the Z direction (SX-SY plane) based on the magnetic fields BX and BY detected by the second and third magnetic field detection units 33 and 34. Figure 4(b) shows the direction of the magnetic field (magnetic field angle) obtained by the calculation unit 36. Specifically, when the display unit 3 is in the first angular interval K1, the calculation unit 36 ​​determines the rotation angle θ as θ = atan2(V2 - VDD / 2, V1 - VDD / 2), and when the display unit 3 is in the second angular interval K2, it determines the rotation angle θ as θ = -atan2(V2 - VDD / 2, V1 - VDD / 2). V1 is the voltage between the first part 331 and the second part 332, and V2 is the voltage between the third part 341 and the fourth part 342. atan2(y, x) is a function that returns θ such that x = rcosθ and y = rsinθ when the Cartesian coordinate system is (x, y) and the polar coordinate system is (r, θ) (where -π < θ ≤ π, θ = 0 coincides with the +x direction, and θ increases counterclockwise). If necessary, a correction term may be added to set the initial rotation angle θ to 0° when the display unit 3 is closed. Note that when the second magnetic field detection unit 33 and the third magnetic field detection unit 34 are configured as a half-bridge, the determination unit 35 and the calculation unit 36 ​​can be provided outside the substrate 37 in the form of a microcomputer or the like.

[0021] PC1 can perform various operations depending on the rotation angle θ. For example, when θ = 180 to 360°, PC1 is used as a tablet, so the operation of the control unit 4 can be disabled. When θ = 0°, the display unit 3 is closed, so PC1 can be put into sleep mode or the brightness of the display unit 3 can be reduced. Alternatively, the brightness and contrast of the display panel 5 of the display unit 3 can be adjusted according to the rotation angle θ.

[0022] In this embodiment, since the relative positional relationship between the magnet 21 and the magnetic sensor 31 remains constant, the magnetic field applied from the magnet 21 to the magnetic sensor 31 depends only on the rotation angle θ. Because the magnetic field applied to the magnetic sensor 31 is not affected by the attitude or orientation of PC1, the rotation angle θ does not become undetectable due to the attitude or orientation of PC1.

[0023] Other embodiments and modifications will be described below, but the configurations and effects that are not described are the same as those of the first embodiment.

[0024] (Second embodiment) In this embodiment, the magnet 21 is attached to the display unit 3, and the magnetic sensor 31 is attached to the PC body unit 2. The magnetic sensor 31 is located away from the center 22 of the magnet 21 in the Z direction. The left column of Figure 6 shows how the display unit 3 rotates relative to the PC body unit 2, and the right column shows how the magnet 21 and magnetic sensor 31 move in conjunction with the rotation of the display unit 3. The movement of the display unit 3 relative to the PC body unit 2 is the same as in the first embodiment. In this embodiment, the position and orientation of the magnetic sensor 31 are constant, but since the magnet 21 rotates along with the rotation of the display unit 3, the magnetic fields detected by the first to third magnetic field detection units 32 to 34 become a function of the rotation angle θ.

[0025] Figure 7(a) shows the magnetic fields BZ, BX, and BY detected by the first to third magnetic field detection units 32 to 34. The magnetic field BX shows the same changes as in the first embodiment. The direction of the magnetic field BY is opposite to that of the first embodiment, but the overall shape is the same as in the first embodiment. The magnetic field BZ is almost zero in the first angle interval K1 and changes sinusoidally in the second angle interval K2. Therefore, in this embodiment as well, the rotation angle θ of the display unit 3 can be detected in the same way as in the first embodiment.

[0026] (Third embodiment) In the third embodiment, as in the first embodiment, the magnet 21 is attached to the PC main body 2 and the magnetic sensor 31 is attached to the display unit 3. Figure 8(a) shows the magnetic fields BZ, BX, and BY detected by the first to third magnetic field detection units 32 to 34. Unlike the first embodiment, in this embodiment the magnetic field BY changes in a sinusoidal pattern with one period while the display unit 3 rotates 360°. That is, the magnetization BY in the first angular interval K1 is in the opposite direction to that of the first embodiment. This type of magnetic field pattern is obtained by positioning the magnetic sensor 31 further away from the magnet 21 in the Z direction than in the first embodiment. Referring to Figure 5, when the magnetic sensor 31 is at the position θ=0°, the magnetic fields BX and BY at the position of the magnetic sensor 31 are the same in the first and third embodiments. However, when the magnetic sensor 31 is at the position θ=90°, the magnetic field BY is in the opposite direction.

[0027] Therefore, it is preferable to position the magnetic sensor 31 at a distance from the magnet 21 in the Z direction. As shown in Figure 8(b), the rotation angle θ and the magnetic field direction have a linear relationship with a one-to-one correspondence over the first and second angular intervals K1 and K2, so there is no need to differentiate based on the magnetic field BY. In this embodiment, the magnetic sensor 31 of the first embodiment can also be used, but the determination unit 35 is unnecessary, and the first magnetic field detection unit 32 is also unnecessary. Although not shown, the magnet 21 may be attached to the display unit 3 and the magnetic sensor 31 may be attached to the PC main unit 2. In other words, this embodiment can also be combined with the second embodiment.

[0028] As an alternative configuration, the angle sensor 41 shown in Figure 9 can be used as the magnetic sensor 31. The angle sensor 41 consists of first to fourth magnetic field detection units 42 to 45 connected by a bridge. The first magnetic field detection unit 42 and the second magnetic field detection unit 43 are connected in series to form a first pair 46, and the third magnetic field detection unit 44 and the fourth magnetic field detection unit 45 are connected in series to form a second pair 47. One end of the first pair 46 and the second pair 47 are connected to the power supply VDD and the other end is grounded (GND). The first magnetic field detection unit 42 and the fourth magnetic field detection unit 45 are located on the power supply VDD side, and the second magnetic field detection unit 43 and the third magnetic field detection unit 44 are located on the grounded side (GND). Each of the first to fourth magnetic field detection units 42 to 45 is equipped with a magnetoresistive element 38 as shown in Figure 3. The magnetization direction M1 of the magnetization fixed layer 383 of the first magnetic field detection unit 42 and the magnetization direction M2 of the magnetization fixed layer 383 of the second magnetic field detection unit 43 are in opposite directions (with a 180° angle difference), and the magnetization direction M3 of the magnetization fixed layer 383 of the third magnetic field detection unit 44 and the magnetization direction M4 of the magnetization fixed layer 383 of the fourth magnetic field detection unit 45 are in opposite directions (with a 180° angle difference). The magnetization directions M1, M2 and the magnetization directions M3, M4 are orthogonal. Therefore, the first set 46 detects the magnetic field BX (or BY), and the second set 47 detects the magnetic field BY (or BX). The angle sensor 41 has a calculation unit 48 that performs calculations based on the output V1 between the first magnetic field detection unit 42 and the second magnetic field detection unit 43 and the output V2 between the third magnetic field detection unit 44 and the fourth magnetic field detection unit 45. The calculation unit 48 calculates atan(V2 / V1) and outputs the rotation angle θ. Therefore, the angle sensor 41 can detect the direction of the combined magnetic field of two magnetic fields in a plane (SX-SY plane) that is perpendicular to the Z direction and also perpendicular to each other. The angle sensor 41 can be simplified in configuration compared to the magnetic sensor 31 described above.

[0029] (modified version) Figure 10 shows several variations of the rotation angle detection device 11. The rotation angle detection device 11 is located in the limited space between the PC main unit 2 and the display unit 3, and the position and shape of the space vary. Therefore, applying the variations shown below will increase its applicability to various PCs 1. As shown in Figure 10(a), the rotation angle detection device 11 may have a soft magnetic material 23 attached to the magnet 21. The soft magnetic material 23 functions as a yoke, strengthening the magnetic field applied to the magnetic sensor 31.

[0030] As shown in Figure 10(b), the magnet 21 may be cylindrical. As shown in Figure 10(c), the magnet 21 may be cylindrical. In these modifications, the magnetization direction of the magnet 21 may be in any direction in the MX-MY plane. In these modifications, the central axis of the magnet 21 can be aligned with the first rotation axis 6.

[0031] As shown in Figure 10(d), the magnetization direction of the magnet 21 may be tilted from a direction perpendicular to the Z direction, and the magnet 21 may be magnetized in any direction different from the Z direction. If the magnetic sensor is at the center of the magnet in the MX direction, and the magnet 21 is magnetized in the Z direction, the magnetic field BX will be zero, and the rotation angle θ cannot be detected.

[0032] As shown in Figure 10(e), the magnetic sensor 31 may be mounted on the SX-Z plane, or, although not shown, on the SY-Z plane. As shown in Figure 10(f), the central axis of the magnet 21 may be separated from the first rotation axis 6 and the second rotation axis 7. This modified example increases the degree of freedom in the installation position of the magnet 21.

[0033] (Note) This specification includes the following disclosures. [Configuration 1] It comprises a magnet attached to one of a first member and a second member rotatably supported by the first member, and a magnetic sensor attached to the other, The first member has a first axis of rotation extending in a first direction, the second member has a second axis of rotation parallel to the first axis of rotation, the second member rotates around the first axis of rotation over a first angular section, and rotates around the second axis of rotation over a second angular section continuous with the first angular section. The magnetic sensor detects the direction of the magnetic field in a plane perpendicular to the first direction, A rotation angle detection device wherein the magnetic sensor is located away from the center of the magnet in the first direction. [Configuration 2] The rotation angle detection device according to configuration 1, wherein the first and second angle intervals are 180°. [Configuration 3] The aforementioned magnetic sensor is A first magnetic field detection unit that detects a magnetic field in the first direction, A determination unit that determines whether the second member is in the first angular interval or the second angular interval based on the magnetic field in the first direction, A rotation angle detection device according to configuration 1 or 2, having the following features. [Structure 4] The rotation angle detection device according to configuration 3, wherein the determination unit makes the determination based on whether the magnetic field in the first direction is greater than or less than a reference value. [Composition 5] The aforementioned magnetic sensor is Second and third magnetic field detection units that detect magnetic fields in two directions that are perpendicular to the first direction and mutually perpendicular, A calculation unit that determines the direction of the magnetic field based on the determination of the determination unit and the magnetic fields detected by the second and third magnetic field detection units, A rotation angle detection device according to configuration 3 or 4, having the following features. [Composition 6] The rotation angle detection device according to configuration 1 or 2, wherein the magnetic sensor detects the direction of the composite magnetic field of two magnetic fields that are orthogonal to the first direction and mutually orthogonal, and the direction of the composite magnetic field corresponds one-to-one with the rotation angle of the second member over the first and second angular intervals. [Composition 7] The rotation angle detection device according to configuration 6, wherein the magnetic sensor is separated from the magnet in the first direction. [Structure 8] A rotation angle detection device according to any one of configurations 1 to 7, having a soft magnetic material attached to the magnet. [Composition 9] The rotation angle detection device according to any one of configurations 1 to 8, wherein the magnet is magnetized in a direction other than the first direction. [Configuration 10] The rotation angle detection device according to any one of configurations 1 to 9, wherein the magnet is attached to the first member and the magnetic sensor is attached to the second member. [Composition 11] The rotation angle detection device according to any one of configurations 1 to 9, wherein the magnet is attached to the second member and the magnetic sensor is attached to the first member. [Composition 12] The rotation angle detection device according to any one of configurations 1 to 11, wherein the magnetic sensor has a TMR element. [Composition 13] The first member and A second member rotatably supported on the first member, The device comprises a rotation angle detection device as described in any one of configurations 1 to 12, A folding machine in which the magnet of the rotation angle detection device is attached to one of the first member and the second member, and the magnetic sensor of the rotation angle detection device is attached to the other of the first member and the second member. [Composition 14] The folding machine according to configuration 13, wherein the folding machine is a personal computer in which the first component is an operating unit and the second component is a display panel. [Explanation of symbols]

[0034] 1. Personal computer (foldable device) 2 PC main unit 3. Display section 6. First axis of rotation 7. Second axis of rotation 11. Rotation Angle Detection Device 21 Magnets 23 Soft magnetic material 31 Magnetic Sensor 32-34 First to third magnetic field detection units 35 Judgment section 36 Arithmetic section

Claims

1. It comprises a magnet attached to one of a first member and a second member rotatably supported by the first member, and a magnetic sensor attached to the other of the two members, The first member has a first axis of rotation extending in a first direction, the second member has a second axis of rotation parallel to the first axis of rotation, the second member rotates around the first axis of rotation over a first angular section, and rotates around the second axis of rotation over a second angular section continuous with the first angular section. The magnetic sensor detects the direction of the magnetic field in a plane perpendicular to the first direction, A rotation angle detection device wherein the magnetic sensor is located away from the center of the magnet in the first direction.

2. The rotation angle detection device according to claim 1, wherein the first and second angle intervals are 180°.

3. The aforementioned magnetic sensor is A first magnetic field detection unit that detects a magnetic field in the first direction, A determination unit that determines whether the second member is in the first angular section or the second angular section based on the magnetic field in the first direction, A rotation angle detection device according to claim 1, having the following features.

4. The rotation angle detection device according to claim 3, wherein the determination unit performs the determination based on whether the magnetic field in the first direction is greater than or less than a reference value.

5. The aforementioned magnetic sensor is Second and third magnetic field detection units that detect magnetic fields in two directions that are perpendicular to the first direction and mutually perpendicular, A calculation unit that determines the direction of the magnetic field based on the determination of the determination unit and the magnetic fields detected by the second and third magnetic field detection units, A rotation angle detection device according to claim 3, having the following features.

6. The rotation angle detection device according to claim 1, wherein the magnetic sensor detects the direction of the composite magnetic field of two magnetic fields perpendicular to the first direction and perpendicular to each other, and the direction of the composite magnetic field corresponds one-to-one with the rotation angle of the second member over the first and second angular intervals.

7. The rotation angle detection device according to claim 6, wherein the magnetic sensor is separated from the magnet in the first direction.

8. The rotation angle detection device according to claim 1, comprising a soft magnetic material attached to the magnet.

9. The rotation angle detection device according to claim 1, wherein the magnet is magnetized in a direction other than the first direction.

10. The rotation angle detection device according to claim 1, wherein the magnet is attached to the first member and the magnetic sensor is attached to the second member.

11. The rotation angle detection device according to claim 1, wherein the magnet is attached to the second member and the magnetic sensor is attached to the first member.

12. The rotation angle detection device according to claim 1, wherein the magnetic sensor has a TMR element.

13. The first member and A second member rotatably supported by the first member, A rotation angle detection device according to any one of claims 1 to 12, A folding machine in which the magnet of the rotation angle detection device is attached to one of the first member and the second member, and the magnetic sensor of the rotation angle detection device is attached to the other of the first member and the second member.

14. The folding machine according to claim 13, wherein the folding machine is a personal computer in which the first member comprises an operating section and the second member comprises a display panel.

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