JP2010122172A - Detection apparatus for rotation angle, and detection method of rotation angle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a detection apparatus for rotation angle and a detectiion method of rotation angle, having small increment of detection error with respect to the deviation in offset. <P>SOLUTION: A magnetic sensor 3 includes a first field-detecting domain A, detecting only the field of one direction and a second field-detecting domain B, detecting only a field of one direction perpendicular to the one direction. The magnetic sensor 3 is deployed, such that the first field-detecting domain A is located nearer to the rotation axis of a magnet 2 than to the second field detecting domain B, a direction of detecting field of the first field-detecting domain A is the direction of perpendicular line t dropped on the axis of rotation of the magnet 2 from the first field detecting domain A, and the direction of the detecting field of the second field-detecting domain B is the direction of a line that perpendicularly intersects a vertical line t. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rotation angle detection device and a rotation angle detection method in which an increase in detection error with respect to offset deviation is small.

  A rotating body such as a steering shaft is used for electric power steering mounted on a vehicle. Some rotation angle detection devices that detect the rotation angle of such a rotating body rotate the magnet as the rotating body rotates. The change in the magnetic field accompanying the rotation of the magnet is detected by the magnetic sensor, the rotation angle of the magnet is detected from the change in the magnetic field, and the rotation angle of the rotating body is detected from the rotation angle of the magnet.

  FIG. 10 shows a conventional rotation angle detection device 101. A main gear 102 attached to a rotating body (not shown) and a sensor gear 103 that meshes with the main gear 102 are installed. A magnet 104 is mounted on the sensor gear 103, and a magnetic sensor 105 is arranged facing the magnet 104. The calculation unit 106 performs a calculation for obtaining the rotation angle from the magnetic field. In FIG. 10, the magnetic sensor 105 is disposed beside the magnet 104, but the magnetic sensor 105 may not be disposed beside the magnet 104, and a change in the magnetic field by the magnet 104 such as on the magnet 104 can be detected. The magnetic sensor 105 can be disposed at the position.

  The magnetic sensor 105 is realized by an MR (Magnet-Resistsnce) element, a GMR (Giant Magnet-Resistsnce) element, a Hall element, or the like.

  In the rotation angle detection device of FIG. 10, the magnetic sensor 105 detects a magnetic field generated by the magnet 104 that rotates as the sensor gear 103 rotates, and the change in the magnetic field corresponds to the rotation angle of the magnet 104. ing. Since the rotation angle of the magnet 104 is the same as the rotation angle of the sensor gear 103, the rotation angle of the main gear 102 can be detected from the rotation angle of the magnet 104. The rotation angle of the main gear 102 is the rotation to which the main gear 102 is attached. Since it is the same as the rotation angle of the body, the rotation angle of the rotation body can be detected after all.

JP 2006-322794 A JP 2006-292423 A

  In the conventional rotation angle detection device 101, a positional shift occurs in the main gear, the sensor gear, the magnet, and the magnetic sensor due to the mounting shift in the assembly process or the axial shift of the rotating body that occurs during operation. Due to the positional deviation, an error (hereinafter referred to as detection error) occurs in the rotation angle of the rotating body detected from the rotation angle of the magnet detected by the magnetic sensor or the rotation angle of the magnet.

  FIG. 11 shows the positional relationship between the magnet 104 and the magnetic field detection region E of the magnetic sensor 105. The magnetic field detection region E is a rectangular parallelepiped region formed inside the magnetic sensor 105. Since the magnetic sensor 105 detects the magnetic field only in the magnetic field detection region E, only the magnetic field in the magnetic field detection region E is detected. In FIG. 11, the magnetic sensor 105 is not shown in order to clearly show the magnetic field detection region E inside the magnetic sensor 105.

  As shown in FIGS. 11A to 11C, the magnet 104 is arranged in parallel to the xy plane that is the rotation surface, and the center of the magnet 104 (the center in the x-axis direction and the center in the y-axis direction). It is located on the z axis (0 point on the xy plane) that is the rotation axis. The magnet 104 rotates on a plane parallel to the xy plane, but the x axis and the y axis rotate with the magnet 104. One side of the magnet 104 is parallel to the x axis, the other side is parallel to the y axis, the north and south poles are on the x axis, and the north and south poles are opposite to each other across the y axis. In the position. It is assumed that the magnet 104 rotates counterclockwise around the center (= z axis) of the magnet 104 in a top view.

  The magnetic field detection region E is located at a distance d from the upper surface of the magnet 104 in the z-axis direction, the lower surface of the magnetic field detection region E is parallel to the upper surface of the magnet 104, and the major axis of the magnetic field detection region E is the x axis. Are arranged so that one side surface of the magnetic field detection region E faces the z-axis from the vicinity of the z-axis.

  When it sees in detail, as FIG.11 (d) shows, the magnetic field detection area E does not cross | intersect az axis, but is separated a little from the z axis. A distance Δ between the center (the center in the width direction and the center in the depth direction) C of the magnetic field detection region E and the z axis is referred to as an offset Δ. The offset Δ fluctuates due to the above-described positional deviation during assembly or operation. The rotation angle detection device 101 is designed so that a deviation from the designed offset Δ (hereinafter referred to as an offset deviation) falls within a tolerance range determined from a required specification of the product.

  FIG. 12 shows the relationship between the deviation of the offset Δ and the detection error in the conventional rotation angle detection apparatus 101. Here, a distance Δ between the rotation axis of the magnet 104 and the center C of the magnetic field detection region E of the magnetic sensor 105 is used as an offset. The rotation angle of the magnet 104 is used as the rotation angle.

  As shown in the figure, in the conventional rotation angle detection device 101, the detection error increases as the offset Δ increases.

  11 is not limited to the configuration in which the magnetic sensor is disposed on the upper portion of the magnet 104, but also in the configuration in which the magnetic sensor 105 is disposed on the side of the magnet 104 as illustrated in FIG. For example, the distance (offset Δ) between the magnet 104 and the magnetic sensor 105 may vary.

  Accordingly, an object of the present invention is to solve the above-described problems and provide a rotation angle detection device and a rotation angle detection method in which an increase in detection error with respect to offset deviation is small.

  In order to achieve the above object, a rotation angle detection device of the present invention is a rotation angle at which a magnetic sensor is arranged facing a rotating magnet and the rotation angle of the magnet is detected from a change in the magnetic field detected by the magnetic sensor. In the detection device, the magnetic sensor includes a first magnetic field detection region for detecting only a magnetic field in one direction and a second magnetic field detection region for detecting only a magnetic field in one direction perpendicular to the one direction, and the first magnetic field. The detection area is closer to the rotation axis of the magnet than the second magnetic field detection area, and the direction of the detection magnetic field of the first magnetic field detection area is the direction of a perpendicular line extending from the first magnetic field detection area to the rotation axis of the magnet, The magnetic sensor is arranged so that the direction of the detected magnetic field in the two magnetic field detection region is perpendicular to the perpendicular and is a direction of a straight line parallel to the rotation surface of the magnet.

  The rotation angle of the magnet may be detected from the ratio between the strength of the magnetic field detected by the first magnetic field detection region and the strength of the magnetic field detected by the second magnetic field detection region.

  The rotation axis of the magnet may pass through the midpoint of the N and S poles of the magnet, and the magnetic sensor may be positioned in the direction of the rotation axis of the magnet with respect to the magnet.

  In the rotation angle detection method of the present invention, a magnetic sensor that detects magnetic fields in two directions orthogonal to each other is arranged so that one of the two directions intersects the rotation axis of the rotating magnet. The rotation angle of the magnet is detected from the ratio of the magnetic fields in the two directions.

When the magnetic field in the direction crossing the rotation axis of the magnet detected by the magnetic sensor is H ₁ and the magnetic field in the direction orthogonal to the magnetic field H ₁ is H ₂ , the rotation angle θ of the magnet is arctan (H ₂ / H ₁₎ may be obtained by.

  The present invention exhibits the following excellent effects.

  (1) The increase in detection error with respect to offset deviation is small.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIG. 1, a rotation angle detection device 1 according to the present invention has a magnetic sensor 3 disposed facing a rotating magnet 2, and the rotation of the magnet 2 is detected from a change in magnetic field detected by the magnetic sensor 3. In the rotation angle detection device 1 that detects the angle, the magnetic field sensor 3 detects only a magnetic field in one direction and a second magnetic field that detects only a magnetic field in one direction perpendicular to the one direction. The first magnetic field detection area A is closer to the rotation axis (z axis) of the magnet 2 than the second magnetic field detection area B, and the direction of the detection magnetic field of the first magnetic field detection area A is the first. The direction of the perpendicular t extending from the magnetic field detection area A to the rotation axis of the magnet 2, the direction of the detection magnetic field of the second magnetic field detection area B intersects perpendicularly to the perpendicular t, and the rotation surface (z axis) of the magnet 2 The direction of a straight line u parallel to the xy plane In which the magnetic sensor 3 is disposed. The magnetic sensor 3 is attached to an electronic circuit board (not shown).

  As shown in FIG. 2A, the magnet 2 is attached to the upper surface (xy plane) of the sensor gear 4. The magnetic sensor 3 is disposed above the magnet 2 (in the z-axis direction) while being attached to a substrate (not shown).

  FIG. 2B shows a cross section obtained by cutting the magnetic sensor 3 along a tu plane parallel to the xy plane. The magnetic sensor 3 includes a first magnetic field detection member 31 and a second magnetic field detection member 32 therein. The 1st magnetic field detection member 31 and the 2nd magnetic field detection member 32 consist of conductive wiring for electricity supply connected to the power supply which is not illustrated. The conductor wiring is preferably made of a magnetic material (pure iron, permalloy, etc.) and is produced on the substrate by a thin film technique. As shown in FIG. 2B, the conductor wiring is formed into a shape in which a strip-like pattern having a sufficiently narrow width than the width of the surface is repeatedly folded and packed in a rectangular surface. The first magnetic field detection member 31 is configured such that a current flows in the u direction. On the other hand, the second magnetic field detection member 32 is configured such that a current flows in the t direction.

  In the magnetic sensor 3, the first magnetic field detection region A is formed by the first magnetic field detection member 31 and the second magnetic field detection region B is formed by the second magnetic field detection member 32 by the internal structure as described above. .

  In the magnetic sensor 3, when the external magnetic field H is not present, the direction of each magnetization vector generated inside the first magnetic field detection member 31 and the second magnetic field detection member 32 coincides with the direction of each current.

  As shown in FIG. 2C, when the external magnetic field H is applied perpendicularly to the current direction, each magnetization vector generated inside the first magnetic field detection member 31 and the second magnetic field detection member 32 is shown. Each direction rotates by an angle α. As a result, the electric resistance R of the first magnetic field detection member 31 and the second magnetic field detection member 32 changes as a function of the magnetization vector rotation angle α expressed by the following equation (2) (magnetoresistance effect).

R = R ₀ + ΔR ₀ cos 2α (2)
R ₀ and ΔR ₀ are constant constant voltages of the magnetic material, the currents flowing through the first magnetic field detection member 31 and the second magnetic field detection member 32 are always measured, and changes in the electric resistance R are detected from the current values. By doing so, the magnetization vector rotation angle α is obtained. Thus, the magnitude of the external magnetic field H in the direction perpendicular to the current direction can be detected. That is, the first magnetic field detection member 31 can detect a magnetic field in the t direction, and the second magnetic field detection member 32 can detect a magnetic field in the u direction.

  As shown in FIG. 3, the first magnetic field detection region A and the second magnetic field detection region B are each formed in a rectangular parallelepiped shape, and come into contact with each other to form the first magnetic field detection region A and the second magnetic field detection region. The whole combined with B forms an integral rectangular parallelepiped shape. The center of the entire rectangular parallelepiped (the center of the width, the center of the depth, and the center of the height) C is on the boundary surface where the first magnetic field detection area A and the second magnetic field detection area B are combined. It is located at the intersection of four diagonal lines for the eight vertices of the rectangular parallelepiped. The volume of the first magnetic field detection area A and the volume of the second magnetic field detection area B are equal.

  In the first magnetic field detection area A, the magnetic sensor 3 detects only one unidirectional component of the magnetic field passing through the first magnetic field detection area A, and the value is a point in the first magnetic field detection area A. The integrated value is obtained by integrating the magnetic field in the entire first magnetic field detection area A. Specifically, in the first magnetic field detection region A, only the magnetic field in the width direction is detected.

  In the second magnetic field detection region B, the magnetic sensor 3 detects only one directional component of the magnetic field passing through the second magnetic field detection region B, and the value is a point in the second magnetic field detection region B. Is an integrated value obtained by integrating the magnetic field in the entire second magnetic field detection region B. Specifically, in the second magnetic field detection region B, only the magnetic field in the depth direction is detected. This is a magnetic field in one direction perpendicular to the magnetic field in one direction detected in the first magnetic field detection region A.

The total of the first magnetic field detection region A and the second magnetic field detection region B is a rectangular parallelepiped having a width M ₁ , a depth M ₂ , and a height M ₃ . The first magnetic field detection region A and the second magnetic field detection region B divide the rectangular parallelepiped width M ₁ into two. The first magnetic field detection area A so as to detect only the magnetic field H ₁ in the width direction. The second magnetic field detection region B detects only the magnetic field H _{2 in the} depth direction perpendicular to the width direction.

  As shown in FIGS. 4A to 4C, the magnet 2 is arranged in parallel to the xy plane that is the rotation surface, and the center of the magnet 2 (the center in the x-axis direction and the center in the y-axis direction) is set. It is located on the z axis (0 point on the xy plane) that is the rotation axis. The magnet 2 rotates on a plane parallel to the xy plane, but the x axis and the y axis rotate with the magnet 2. One side of the magnet 2 is parallel to the x axis, the other side is parallel to the y axis, the north and south poles are on the x axis, and the north and south poles are opposite to each other across the y axis. And opposite positions with respect to the z-axis. It is assumed that the magnet 2 rotates counterclockwise around the center (= z axis) of the magnet 2 when viewed from above.

The magnet 2 is a rectangular parallelepiped having a length of L _{1 in} the x-axis direction, L _{2 in the} y-axis direction, and L _{3 in} the z-axis direction. The magnet 2 has a magnet coercive force H ₀ (kA / m).

  The magnet 2 is attached to the sensor gear, the main gear rotates with the rotation of the rotating body, the sensor gear rotates with the rotation of the main gear, and the magnet 2 rotates with the rotation. (See FIGS. 8 and 10).

  The first magnetic field detection region A and the second magnetic field detection region B are located at a distance d from the upper surface of the magnet 2 in the z-axis direction. The lower surfaces of the first magnetic field detection region A and the second magnetic field detection region B are parallel to the upper surface of the magnet 2. In the state of FIG. 4, the width direction of the first magnetic field detection region A and the second magnetic field detection region B is parallel to the x axis, and the center C of the entire rectangular parallelepiped of the first magnetic field detection region A and the second magnetic field detection region B. Is located on the x-axis. One side surface of the first magnetic field detection region A (the surface not in contact with the second magnetic field detection region B) faces the z axis from the vicinity of the z axis. The distance (see FIG. 5) between the center C of the entire rectangular parallelepiped of the first magnetic field detection region A and the second magnetic field detection region B and the z axis is defined as an offset Δ.

  Hereinafter, the operation of detecting the rotation angle by the rotation angle detection device 1 of the present invention will be described with reference to FIGS.

  As shown in FIG. 4B, the magnet 2 rotates counterclockwise around the z axis when viewed from above. Even when the magnet 2 rotates, the offset Δ, which is the distance between the center C of the entire rectangular parallelepiped of the first magnetic field detection region A and the second magnetic field detection region B, and the z axis is maintained constant.

When viewed from a system rotating with the magnet 2 (xyz system), as shown in FIG. 5A, the first magnetic field detection area A and the second magnetic field detection area B rotate clockwise in top view. The first magnetic field detection area A is located inside the rotation, and the second magnetic field detection area B is located outside the rotation. In this case, the magnetic sensor 3, as shown in FIG. 5 (b), the magnetic field H ₁ is detected in the first magnetic field detection region A, the magnetic field H ₂ is detected in the second magnetic field detection region B.

In the present invention, the rotation angle of the magnet 2 is detected from the ratio between the magnetic field H ₁ and the magnetic field H ₂ . The rotation angle of the sensor gear can be detected from the rotation angle of the magnet 2, the rotation angle of the main gear can be detected from the rotation angle of the sensor gear, and the rotation angle of the rotating body can be detected from the rotation angle of the main gear.

The angle formed by the direction of the perpendicular t drawn from the first magnetic field detection area A to the rotation axis (z-axis) of the magnet 2 and the direction from the N pole to the S pole of the magnet 2 is arctan (H ₂ / H ₁ ). is there. Let θ be the angle formed by the direction of the perpendicular t drawn from the actual first magnetic field detection region A to the rotation axis (z-axis) of the magnet 2 and the direction from the N pole to the S pole of the magnet 2.

The detection error ε is
ε = arctan (H ₂ / H ₁ ) −θ (1)
It is expressed. The reason will be described below.

The magnetic field vectors existing in the first magnetic field detection area A and the second magnetic field detection area B of the magnetic sensor 3 are not parallel regardless of the location. As shown in FIG. 6 (b), the magnetic field vector at the point P _A on the perpendicular t drawn from the first magnetic field detection area A to the rotation axis of the magnet 2 and the perpendicular t far from the origin 0 to the point P _A. looking than the magnetic field vector at P _B point that is, the magnetic field vector acting on P _B that it is outside of the rotating magnetic field vector acting on the inner and it points P _a of rotation, not the same. The absolute value of the magnetic field H ₁ in the width direction (in the direction of the perpendicular t) of the first magnetic field detection area A and the second magnetic field detection area B decreases as the distance from the rotation axis (z axis; origin 0) increases. The magnetic field H _{2 in the} direction (perpendicular u direction) is almost the same at a position close to and far from the rotation axis.

From this, the rotation angle from the ratio of the magnet 2 with the strength of the magnetic field H ₂ the intensity of the magnetic field H ₁ of the first magnetic field detection area A is detected and the second magnetic field detection region B is detected is detected.

As shown in FIG. 6A, the position along the vertical line t is taken as the horizontal axis, and the position of the rotation axis is set as the origin 0. The magnetic fields obtained by normalizing the magnetic fields H ₁ and H ₂ with the magnet coercive force H ₀ of the magnet 2 are plotted on the vertical axis and shown in the graph. The upper graph in FIG. 6A is for the magnetic field H ₁ , and it can be seen that the absolute value of the magnetic field H ₁ is larger as the position is closer to the rotation axis. The lower graph in FIG. 6A is for the magnetic field H ₂ , and it can be seen that the absolute value of the magnetic field H ₂ is substantially constant regardless of the distance from the rotation axis.

Accordingly, the first magnetic field detection region A for detecting the magnetic field H _{1 in} the direction of the perpendicular t is located on the side close to the rotation axis, and the second magnetic field detection region B for detecting the magnetic field H ₂ in the direction of the perpendicular u is located on the far side. By arranging the magnetic sensor 3 so as to reduce the value of arctan (H ₂ / H ₁ ) in the equation (1), the detection error ε can be reduced.

As shown in FIG. 7, when comparing the case where the first magnetic field detection region A and the second magnetic field detection region B are at respective positions around the origin 0, the sign of the magnetic field H ₁ is at the lower right position. Since the sign of the magnetic field H ₂ is −, the angle θ between the perpendicular t and the x axis is +. In the upper right position, the sign of the magnetic field H ₁ is −, and the sign of the magnetic field H ₂ is +, so that the angle θ between the perpendicular t and the x axis is −. Incidentally, the sign of the magnetic field H ₂ defines a counterclockwise + and the sign of the magnetic field H ₁ defines the direction away from the origin 0 + a.

On the other hand, since the sign of the magnetic field H ₁ is − and the sign of the magnetic field H ₂ is − at the upper left position, the angle θ between the perpendicular t and the x axis is +. The angle θ detected at this time is the same as the angle θ detected at the lower right position. Therefore, it can be seen that the rotation angle detection device 1 of the present invention can detect the rotation angle θ of the magnet 2 in a range of at least −90 ° to + 90 °.

Here, the detection method of the rotation angle of the rotating body will be described. In the rotation angle detecting device 81 shown in FIG. 8, the main gear 82 is overlapped with the rotating body 83 by overlapping two gears 82a and 82b having different numbers of teeth. It is an integrated one. Sensor gears 84 and 84 mesh with the first main gear 82a and the second main gear 82b, respectively. Magnets 85, 85 are attached to the upper surfaces of the sensor gears 84, 84, and magnetic sensors (not shown) are arranged on the upper, lateral, and diagonally upper sides of the respective magnets 85, 85. That is, two sets of the rotation angle detection device 1 of the present invention described in FIG. 1 are used. Since the rotation angles of the two sensor gears 84 and 84 are different from each other with respect to the rotation of the rotating body 83, detection is performed by relative rotation between the magnets 85 and 85 attached to the upper surfaces of the sensor gears 84 and 84 and the respective magnetic sensors. Arctan (H ₂ / H ₁ ) values (values in the range of −90 ° to 90 °) differ.

The number of teeth of the two gears 82a and 82b of the main gear 82 is Za and Zb, the number of teeth of the sensor gear 84 is Zc, and the difference between the values of arctan (H ₂ / H ₁ ) of the _two sensor gears 84 and 84 is calculated. When ΔΦ, the rotation angle Φ of the rotating body 83 is expressed by the following equation (3):

It is expressed.

  In the rotation angle detection device 81 shown in FIG. 8, by appropriately selecting the number of teeth Za, Zb, Zc, a rotation angle in a wider range than −90 ° to + 90 ° (for example, −780 ° to + 780 °, etc.) Can be detected.

As shown in FIG. 9, in the conventional technique, the magnetic field synthesized in the entire single magnetic field detection region E is detected. Therefore, when the deviation of the offset Δ increases, the detection error ε increases remarkably. On the other hand, in the present invention, the magnetic field H _{1 in} the direction of the normal t with respect to the rotation axis is detected in the first magnetic field detection region A close to the rotation axis, and the perpendicular u to the normal t in the second magnetic field detection region B far from the rotation axis. Since the magnetic field H ₂ is detected, an increase in the detection error ε is suppressed even when the offset Δ becomes large. Therefore, the detection error ε can be reduced.

  In the present invention, two sets of sensor gears, magnets, and magnetic sensors may be used as in the rotation angle detection device 101 of FIG.

  In this case, the rotation angle detection device 101 includes a main gear 102 attached to the rotating body and two sensor gears 103 having different gear ratios meshed with the main gear 102, and magnets 104 are respectively provided to the two sensor gears 103. The magnetic sensor 105 is arranged facing each magnet 104, the rotation angle of each magnet 104 is detected from the change of the magnetic field detected by each magnetic sensor 105, the rotation angle of each magnet 104 and the above two The rotation angle of the rotating body is detected from the gear ratio of the sensor gear 103 to the main gear 102.

It is a perspective view of the rotation angle detection apparatus which shows one Embodiment of this invention. (A) is a structural diagram showing the arrangement of the magnet and the magnetic sensor, (b) is an internal structural diagram of the magnetic sensor, (c) is a diagram showing the magnetic field detection principle. It is a perspective view which shows the shape of the 1st magnetic field detection area | region and 2nd magnetic field detection area | region formed in the magnetic sensor of FIG. It is a figure of the rotation angle detection apparatus of this invention, (a) is a side view, (b) is a top view, (c) is a perspective view. It is a figure which shows the state rotated from the state of FIG. 4 of the rotation angle detection apparatus of this invention, (a) is a top view, (b) is the elements on larger scale of (a). (A) is a figure showing the magnitude | size of the magnetic field ratio on the perpendicular t, (b) is a magnetic field vector figure in the state of FIG. It is a magnetic field vector figure in a plurality of rotation angles of a rotation angle detection device of the present invention. It is a top view of the rotation angle detection apparatus of the rotary body using the rotation angle detection apparatus of this invention. FIG. 6 is a characteristic diagram of offset deviation versus detection error according to the present invention and the prior art. It is a functional block diagram of a rotation angle detection apparatus. It is a figure of the rotation angle detection apparatus of the rotary body using the conventional rotation angle detection apparatus, (a) is a side view, (b) is a top view, (c) is a perspective view, (d) is a figure of (b). It is a partial enlarged view. FIG. 6 is a characteristic diagram of offset deviation versus detection error according to the prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotation angle detection apparatus 2 Magnet 3 Magnetic sensor 4 Sensor gear 31 1st magnetic field detection member 32 2nd magnetic field detection member A 1st magnetic field detection area B 2nd magnetic field detection area

Claims (5)

In a rotation angle detection device in which a magnetic sensor is arranged facing a rotating magnet and the rotation angle of the magnet is detected from a change in the magnetic field detected by the magnetic sensor.
A first magnetic field detection region for detecting only a magnetic field in one direction and a second magnetic field detection region for detecting only a magnetic field in one direction perpendicular to the one direction are formed inside the magnetic sensor,
The first magnetic field detection area is closer to the rotation axis of the magnet than the second magnetic field detection area, and the direction of the detection magnetic field of the first magnetic field detection area is in the direction of a perpendicular line dropped from the first magnetic field detection area to the rotation axis of the magnet. The magnetic sensor is arranged such that the direction of the detected magnetic field of the second magnetic field detection region intersects the perpendicular to the perpendicular and is a straight line parallel to the rotation surface of the magnet. Rotation angle detector.   2. The rotation angle detection device according to claim 1, wherein the rotation angle of the magnet is detected from a ratio between a magnetic field intensity detected by the first magnetic field detection area and a magnetic field intensity detected by the second magnetic field detection area. .   The rotation axis of the magnet passes through the midpoint of the north and south poles of the magnet, and the magnetic sensor is located in the direction of the rotation axis of the magnet with respect to the magnet. Rotation angle detection device.   A magnetic sensor that detects magnetic fields in two directions orthogonal to each other is arranged so that one of the two directions intersects the rotation axis of the rotating magnet, and the magnet is calculated from the ratio of the detected magnetic fields in the two directions. A rotation angle detection method characterized by detecting a rotation angle. When the magnetic field in the direction intersecting the rotation axis of the magnet detected by the magnetic sensor is H ₁ and the magnetic field in the direction orthogonal to the magnetic field H ₁ is H ₂ ,
5. The rotation angle detection method according to claim 4, wherein the rotation angle θ of the magnet is obtained by arctan (H ₂ / H ₁ ).

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