JP4897955B2 - Rotation angle detector - Google Patents

Description

  The present invention relates to a rotation angle detection device that detects a rotation angle of a rotating body.

  For example, a rotation angle detection device is disclosed that is attached to a rotating body such as a steering shaft of an automobile and detects the rotation angle of the rotating body.

  The conventional rotation angle detection device disclosed in Patent Document 1 is rotated at a rotational speed higher than that of the rotating plate by a rotating plate rotated by a detected rotating body whose angle is to be detected, and the detected rotating body or rotating plate. With gears. The rotary plate is provided with an absolute signal type encoder using an optical sensor, and this encoder outputs a code signal having one rotation of the rotary plate as one cycle as a rotation angle detection signal of the rotary plate. The gear is provided with a magnetic sensor using a magnet and a magnetoresistive element, and the magnetic sensor outputs an analog signal having one rotation of the gear as one cycle as a gear rotation angle detection signal. Then, the rotation angle of the detected rotating body is calculated from the combination of the respective rotation angle detection signals output by these encoders and magnetic sensors.

JP 2002-98522 A

  However, the conventional rotation angle detection device has a problem that if the detection angle range of the rotation angle of the detected rotating body is to be widened, the diameter of the gear has to be increased, so that the device becomes large.

  The present invention has been made in view of the above, and an object of the present invention is to provide a rotation angle detection device capable of realizing a wide detection angle range without increasing the size of the device.

In order to solve the above-described problems and achieve the object, a rotation angle detection apparatus according to the present invention is a rotation angle detection apparatus that detects a rotation angle of a detected rotating body, and is fixed to the detected rotating body. A main rotating body that rotates together with the detected rotating body, a sub-rotating body that rotates at a predetermined rotation ratio with respect to the main rotating body, and a period according to the rotation of the main rotating body, where n is an integer of 2 or more. A main rotation detection mechanism that outputs a continuous signal that changes periodically with a cycle number n per rotation, and a continuous signal that periodically changes according to the rotation of the sub-rotator, where m is an integer smaller than n and greater than or equal to 1 Signal processing for calculating the rotation angle of the main rotating body and the sub-rotating body using the sub-rotation detecting mechanism that outputs at a cycle number m per rotation, and the signals that the main rotation detecting mechanism and the sub-rotation detecting mechanism output Means and the calculated main rotor or The rotation angle of the sub rotatable bodies, and relative angles between the rotation angle and the angle of said multiplied by a predetermined rotation ratio of the rotation angle of the sub rotatable bodies of said main rotating body, said main rotation detection mechanism and the auxiliary rotary Arithmetic processing means for calculating a rotation angle of the detected rotating body based on a cycle of a signal output from the detection mechanism.

  The rotation angle detection apparatus according to the present invention is characterized in that, in the above invention, m is 1.

  In the rotation angle detection device according to the present invention, in the above invention, the main rotation detection mechanism or the sub rotation detection mechanism is attached to the main rotation body or the sub rotation body and is continuously and periodically in a rotation direction. And a magnet for generating a magnetic field whose intensity changes, and two magnetic detection elements arranged in the vicinity of the magnet so as to form a predetermined angle around the rotation center of the main rotating body or the sub rotating body. It is characterized by that.

  In the rotation angle detection apparatus according to the present invention as set forth in the invention described above, the magnetic detection element is a Hall element.

  In the rotation angle detection device according to the present invention as set forth in the invention described above, the magnetic detection element is a magnetoresistive element.

  The rotation angle detection device according to the present invention outputs a continuous signal that periodically changes according to the rotation of the main rotating body rotating together with the detected rotating body at a cycle number n, where n is an integer of 2 or more. The main rotation detection mechanism and a continuous signal that periodically changes according to the rotation of the sub-rotor rotating at a predetermined rotation ratio with respect to the main rotating body, where m is an integer of 1 or more smaller than n A sub-rotation detection mechanism that outputs at a few m, and by making n a multi-cycle of 2 or more, the period difference can be reduced without increasing the size of the sub-rotator, and the detection angle range can be widened as a result. Therefore, there is an effect that a wide detection angle range can be realized without increasing the size of the apparatus.

  Hereinafter, embodiments of a rotation angle detection device according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment)
FIG. 1 is a schematic cross-sectional view schematically illustrating a rotation angle detection device according to an embodiment of the present invention. The rotation angle detection device according to the present embodiment detects the rotation angle of a steering shaft of an automobile that is a detected rotating body.

As shown in FIG. 1, the rotation angle detection device 1 is a main rotating body that rotates and rotates together with the steering shaft X by attaching and fixing the steering shaft X extending in a direction perpendicular to the paper surface by fitting it in a hole in the center. A ring-shaped main gear 2, a sub-gear 3 that meshes with the main gear 2 and rotates with respect to the main gear 2 at a predetermined rotation ratio, and changes periodically according to the rotation of the main gear 2. The main rotation detection mechanism 4 that outputs a continuous signal, the signal processing means 5 that calculates the rotation angle of the main gear 2 using the signal that the main rotation detection mechanism 4 outputs, and periodically according to the rotation of the auxiliary gear 3 Sub rotation detection mechanism 6 that outputs a continuous signal that changes, signal processing means 7 that calculates the rotation angle of sub gear 3 using the signal that sub rotation detection mechanism 6 outputs, and signal processing means 5 and 7 calculate Rotation of main gear 2 and auxiliary gear 3 Time, relative angles between the rotation angle and the angle obtained by multiplying a predetermined rotation ratio of the rotation angle of the sub-gear 3 of the main gear 2, and the period of the main rotation detecting mechanism 4 and the signal sub-rotation detecting mechanism 6 outputs And an arithmetic processing means 8 for calculating the rotation angle of the steering shaft X based thereon. The gear ratio, that is, the rotation ratio between the main gear 2 and the sub gear 3 is 5/9. Reference numeral 9 denotes a housing of the rotation angle detection device 1.

  The main rotation detection mechanism 4 has a ring-shaped magnet 4a attached to the main gear 2 and an angle of 45 degrees around the rotation center of the main gear 2 at a position 0.5 mm away from the surface of the ring-shaped magnet 4a. Hall elements 4b and 4c arranged as described above. Similarly, the sub-rotation detection mechanism 6 includes a disc-shaped magnet 6a attached to the sub-gear 3 and a rotation center of the sub-gear 3 at a position 0.5 mm away from the surface of the disc-shaped magnet 6a. Hall elements 6b and 6c arranged to form an angle of 90 degrees. The Hall elements 4b, 4c, 6b, 6c are fixed to the rotation angle detection device 1.

  The ring-shaped magnet 4a has two S-pole portions and two N-pole portions arranged alternately, and applies a magnetic field whose intensity changes continuously and periodically in a sinusoidal shape in the rotation direction of the main gear 2 to 2 per rotation. It is a four-pole magnet that is magnetized to generate a period. The Hall elements 4b and 4c detect a magnetic field whose intensity changes corresponding to the rotation of the main gear 2, and each output a voltage signal corresponding to the magnetic field intensity in two periods, that is, two periods. The period of change in magnetic field strength, that is, the period of the voltage signal output from the Hall elements 4b and 4c is 180 degrees, which is a value obtained by dividing 360 degrees by the number of periods 2. On the other hand, the disc-shaped magnet 6a has an S pole portion and an N pole portion alternately arranged one by one, and a magnetic field whose intensity changes continuously and periodically in a sinusoidal shape in the rotation direction of the auxiliary gear 3 is 1 It is a two-pole magnet that is magnetized to generate one cycle per rotation. The Hall elements 6b and 6c detect a magnetic field whose intensity changes corresponding to the rotation of the auxiliary gear 3, and each outputs a voltage signal corresponding to the magnetic field intensity with a cycle number of 1. That is, the period of the voltage signal output from the Hall elements 6b and 6c is 360 degrees which is a value obtained by dividing 360 degrees by the number of periods 1.

  Therefore, if n is the period number of the continuous signal output from the main rotation detection mechanism 4 of the rotation angle detector 1 and m is the period number of the continuous signal output from the sub-rotation detection mechanism 6, n = 2 and m = 1. It is. As will be described later, the detection angle range for the rotation of the shaft X of the rotation angle detection device 1 is obtained by multiplying the cycle of the signal output from the main rotation detection mechanism 4 and the cycle of the signal output from the sub rotation detection mechanism 6 by the gear ratio. The smaller the absolute value of the difference from the given period, the larger it becomes. Therefore, the rotation angle detection device 1 has a wider detection angle range.

  The rotation angle detection device 1 will be described more specifically. FIG. 2 is a block diagram showing the configuration of the main rotation detection mechanism 4, the sub rotation detection mechanism 6, the signal processing means 5, 7 and the arithmetic processing means 8 shown in FIG. The Hall elements 4b and 4c are applied with the voltage amplified by the amplifier A1, detect a magnetic field having a strength corresponding to the rotation of the main gear 2, and output a voltage signal having a voltage value corresponding to the detected magnetic field strength. The amplifiers A2 and A3 amplify the voltage signals output from the Hall elements 4b and 4c to obtain the voltage values S1 and S2 and output them to the signal processing means 5 including a microcontroller. The signal processing means 5 calculates θ1 which is the rotation angle of the main gear 2 using the voltage values S1 and S2, and outputs it to the arithmetic processing means 8 having a microcontroller.

  Similarly, the Hall elements 6b and 6c to which the voltage amplified by the amplifier A4 is applied output a voltage signal having a voltage value corresponding to the detected magnetic field strength. The amplifiers A5 and A6 amplify the voltage signals output from the Hall elements 6b and 6c to obtain voltage values S3 and S4, and output them to the signal processing means 7 having a microcontroller. The signal processing means 7 calculates the rotation angle of the auxiliary gear 3 using the voltage values S3 and S4, calculates θ2 which is an angle obtained by multiplying this rotation angle by the rotation ratio 5/9, and outputs it to the arithmetic processing means 8 To do. Then, the arithmetic processing means 8 calculates the rotation angle Φ of the steering shaft X using θ1 and θ2.

  Next, a method for detecting the rotation angle of the steering shaft X by the rotation angle detection device 1 will be specifically described with reference to FIGS. First, a method for calculating the rotation angle of the main gear 2 will be described with reference to FIG. The voltage values S1 and S2 of the voltage signal input to the signal processing means 5 correspond to one point on each of the sine curves L1 and L2 having a period of 180 degrees as shown in the upper graph of FIG. In this graph, the horizontal axis indicates the rotation angle of the main gear 2 with respect to an arbitrary position, and the vertical axis indicates the voltage of the voltage signal. Further, since the Hall elements 4b and 4c are arranged so as to form an angle of 45 degrees around the rotation center of the main gear 2, the phase difference between the sine curves L1 and L2 is 45 degrees.

Next, the signal processing means 5 normalizes the voltage values S1 and S2 using the following equations (1) and (2). If the normalized values are M1 and M2,
M1 = (S1-S1avg) / S1p (1)
M2 = (S2-S2avg) / S2p (2)

  However, S1avg and S2avg are the average values of the maximum value and the minimum value in one cycle of the voltage signal, respectively, and S1p and S2p are the differences between the maximum value and the minimum value in one cycle of the voltage signal, respectively. For S1avg, S2avg, S1p, and S2p, during assembly adjustment of the rotation angle detection device 1, the main gear 2 is rotated once to obtain voltage signal data, each value is obtained from the data, and stored in the signal processing means 5 Keep it. The normalized values M1 and M2 obtained as described above correspond to one point on each of the sine curves L3 and L4 having a period of 180 degrees as shown in the middle graph of FIG. In this graph, the horizontal axis indicates the rotation angle of the main gear 2 with respect to an arbitrary position, and the vertical axis indicates a normalized value.

  Next, the signal processing means 5 calculates θ1 which is the rotation angle of the main gear 2 using the normalized values M1 and M2. The calculation of θ1 can be performed as follows, for example.

First, θ1 is calculated using Equation (3).
θ1 = 0.5 × Arctan (M1 / M2) + α (3)
However, when M2> 0, α = 45 degrees, when M2 <0, α = 135 degrees, and when M2 = 0, θ1 = 90 degrees when M1> 0, and θ1 = 0 when M1 <0. Degree.

  The angle θ1 calculated by the above method corresponds to one point on the saw-toothed curve L5 having a period of 180 degrees as shown in the lower graph of FIG. In this graph, the horizontal axis represents the rotation angle of the main gear 2 with respect to an arbitrary position, and the vertical axis represents the calculated rotation angle of the main gear 2.

  Next, a method for calculating the rotation angle of the auxiliary gear 3 will be described. This method is substantially the same as the method for calculating the rotation angle of the main gear 2. The voltage values S3 and S4 of the voltage signal input to the signal processing means 7 correspond to one point on each of the sine curves L6 and L7 having a period of 360 degrees as shown in the upper graph of FIG. In this graph, the horizontal axis indicates the rotation angle of the sub-gear 3 with respect to an arbitrary position, and the vertical axis indicates the voltage of the voltage signal. The phase difference between the sine curves L6 and L7 is 90 degrees.

Next, the signal processing means 7 normalizes the voltage signals S3 and S4 to values M3 and M4 using the following equations (4) and (5).
M3 = (S3-S3avg) / S3p (4)
M4 = (S4-S4avg) / S4p (5)

  However, S3avg and S4avg are the average values of the maximum value and the minimum value of the voltage signal, respectively, and S3p and S4p are the differences between the maximum value and the minimum value of the voltage signal, respectively. 3 is rotated once to obtain voltage signal data, each value is obtained from the data, and stored in the signal processing means 7. The normalized values M3 and M4 correspond to one point on each of the sine curves L8 and L9 having a period of 360 degrees as shown in the middle graph of FIG. The horizontal axis indicates the rotation angle of the auxiliary gear 3 with respect to an arbitrary position, and the vertical axis indicates a normalized value.

  Next, the signal processing means 7 calculates the rotation angle of the auxiliary gear 3 using the normalized values M3 and M4, and further calculates θ2, which is an angle obtained by multiplying the rotation angle by the gear ratio. The calculation of θ2 can be performed as follows, for example.

First, θ is calculated using Equation (6).
θ = Arctan (M3 / M4) + α (6)
However, when M4> 0, α = 90 degrees, when M4 <0, α = 270 degrees, and when M4 = 0, θ = 180 degrees if M3> 0, and θ = 0 degrees if M3 <. It is.
Then, θ2 is calculated by multiplying θ by the gear ratio 5/9.

  The angle θ2 calculated by the above method corresponds to one point on the sawtooth curve L10 having a period of 200 degrees as shown in the lower graph of FIG. In this graph, the horizontal axis indicates the rotation angle of the auxiliary gear 3 with respect to an arbitrary position, and the vertical axis indicates the angle obtained by multiplying the rotation angle calculated by the auxiliary gear 3 by the gear ratio.

  Next, the signal processing means 5 and 7 output the angles θ1 and θ2 obtained as described above to the arithmetic processing means 8, respectively. In the rotation angle detection device 1 according to the present embodiment, the cycle T1 of the signal output from the main rotation detection mechanism 4 is 180 degrees as described above, and the gear ratio is 5/9 to the cycle of the signal output from the sub-rotation detection mechanism 6. Since the cycle T2 obtained by multiplying by is 200 degrees, the arithmetic processing means 8 sets the cycle difference between the cycles T1 and T2 to d = | T1−T2 | and uses the equations (7) and (8) for the steering shaft X Φ which is the rotation angle of is calculated.

If θ2 ≦ θ1,
Φ = θ1 + T1 (θ1-θ2) / d (7)
If θ2> θ1,
Φ = θ1 + T1 (θ1−θ2) / d + T1 · T2 / d (8)

  Here, in the case of θ2 ≦ θ1, the relationship among the angles θ1, θ2, periods T1, T2, period difference d, and rotation angle Φ will be described with reference to FIG. The horizontal axis of FIG. 5 represents the detection angle range R = T1 · T2 / | T1-T2 | = 1800 degrees of the rotation angle of the steering shaft X. The saw-shaped curve L11 is obtained by arranging the saw-shaped curve L5 of FIG. However, the vertical axis represents the ratio for one cycle, and the ratio is 100% when the angle is 180 degrees. On the other hand, the saw-tooth curve L12 is obtained by arranging the saw-tooth curve L10 of FIG. However, the vertical axis represents the ratio to one cycle, and the ratio is 100% when the angle is 200 degrees. Note that the rotation angle Φ is 0 degree at the position where the phases of the saw-toothed curves L11 and L12 coincide. At this time, the phases of saw-shaped curves L11 and L12 coincide even at a position where Φ is 1800 degrees.

For example, it is assumed that the angles θ1 and θ2 are calculated for the main gear 2 and the sub gear 3 as shown in FIG. On the other hand, it is assumed that the rotation angle Φ is calculated using Expression (7). In this case, a relative angles between the angle multiplied by the gear ratio to the rotation angle and the rotation angle of the sub-gear 3 of the main gear 2 (θ1-θ2) is the phase of the sawtooth curve L11, L12 in the rotation angle Φ Indicates deviation. Since the saw-toothed curves L11 and L12 are out of phase by a period difference d every time the main gear 2 rotates by one period, (θ1−θ2) / d is the number of rotations of the main gear by the rotation angle Φ. It is a mathematical expression indicating whether or not to include an integer value. Specifically, since the periods T1 and T2 of the main gear 2 and the sub gear 3 are 180 degrees and 200 degrees, respectively, d = 20 degrees. That is, when the main gear 2 rotates by one cycle, the phases of the saw-toothed curves L11 and L12 are shifted by 20 degrees. In FIG. 5, the rotation angle Φ is a value further rotated by the angle θ1 from the state in which the main gear is rotated by three cycles, so (θ1−θ2) / d = 3. That is, since the angles θ1, θ2, the periods T1, T2, the period difference d, and the rotation angle Φ have the above relationships, the rotation angle Φ can be calculated using the equation (7). In the case of θ2> θ1, the mathematical expression taking an integer value indicating how many rotations of the main gear includes the rotation of the main gear is {T2− (θ2−θ1)} / d. The rotation angle Φ is calculated using 8).

  Thus, the detection angle range R is determined by R = T1 · T2 / | T1-T2 |, and the gear ratio k is determined by T2 · m / 360. Therefore, as | T1-T2 | is smaller, R becomes larger and the detection range becomes wider. Therefore, in order to increase R, it is necessary to bring the values of T1 and T2 closer to reduce the difference, but when T1 is large, that is, when the number of periods n is 1, T1 is 360 degrees, or m is large. The gear ratio increases and the gear size increases. For example, when the number of periods of each of the main gear and the sub gear is 1, that is, n = m = 1, as in the above-described conventional rotation angle detection device, if the detection angle range R is set to 1800 degrees, the gear The ratio must be 5/4 or 5/6, and the size of the sub-gear 6 must be comparable to the main gear 2. On the other hand, since the main gear 2 is fixed by being fitted to the steering shaft X, there is a limit in reducing the size of the main gear 2. Therefore, the auxiliary gear must be enlarged in order to realize the above gear ratio, so that the apparatus becomes large. However, in the rotation angle detection device 1, since the cycle number n of the continuous signal output from the main rotation detection mechanism 4 is 2 and the cycle number m is 1, the auxiliary gear 6 is set small in the same detection range. It can be done. m is preferably 1 as much as possible because the structure of the rotation detection mechanism is simplified.

  As described above, the rotation angle detection device 1 according to the present embodiment can realize a wide detection angle range without increasing the size of the device. In the rotation angle detection device 1, the main rotation detection mechanism 4 and the sub rotation detection mechanism 6 output continuous analog signals that change periodically in accordance with the rotation of the main gear 2 or the sub gear 3. . Therefore, as compared with the case of using a conventional encoder that outputs a digital signal, it is possible to reduce the size because it is not necessary to use a disk-shaped rotor having a plurality of slits. In the present embodiment, the angle detection with higher resolution becomes possible as the number of periods of the voltage signal output from the main rotation mechanism is larger and the period is shorter. The reason is that the resolution of AD conversion when inputting a voltage signal corresponding to the angle to be detected to the microcontroller is fixed at 10 bits in full scale, for example, so that the shorter the period of the voltage signal is detected with the same 10 bits. This is because the angle range to be reduced is small. Furthermore, since the rotation angle detection device 1 uses a Hall element as a magnetic detection element, it is possible to further reduce the size, weight, and cost.

In the above embodiment, the formula (7) and the following formula (7a), and the formula (8) and the following formula (8a) are equivalent formulas, so the formula (7a) is used instead of the formula (7). The rotation angle Φ may be calculated by using the equation (8a) instead of the equation (8).
Φ = θ2 + T2 (θ1-θ2) / d (7a)
Φ = θ2 + T2 (θ1-θ2) / d + T1 · T2 / d (8a)

In the above embodiment, since T1 <T2, Equations (7) and (8) are used when calculating the rotation angle of the steering shaft X. When T1> T2, the following equation ( 9) and (10) can be used to calculate the rotation angle.
If θ1 ≦ θ2,
Φ = θ1 + T1 (θ2−θ1) / d (9)
If θ1> θ2,
Φ = θ1 + T1 (θ2−θ1) / d + T1 · T2 / d (10)

  In the above embodiment, a Hall element is used as the magnetic detection element. However, a magnetoresistive element having a small temperature characteristic and a high angular resolution may be used according to the application of the rotation angle detection device.

  Further, as a modification of the above embodiment, if the detection angle range R is 1800 degrees, the period number m is 1 and the period number n is 3, T2 = 112.5, the gear ratio is 5/16, and the auxiliary gear is Can be small. In order to set n to 3, three S pole portions and N pole portions are alternately arranged as ring-shaped magnets attached to the main gear, and are continuously and periodically sinusoidally in the rotation direction of the main gear. In particular, a 6-pole magnet that is magnetized so as to generate a magnetic field whose intensity changes three times per rotation may be used. Note that m is not limited to 1, but can be 2 or more and smaller than n, but 1 is preferable in order to reduce the size of the auxiliary gear. The values of n and m can be easily set to desired values by appropriately arranging the S pole portion and the N pole portion of the magnet attached to the main gear or the sub gear.

1 is a schematic cross-sectional view schematically illustrating a rotation angle detection device according to an embodiment of the present invention. It is a block diagram which shows the structure of the main rotation detection mechanism, subrotation detection mechanism, signal processing means, and arithmetic processing means which are shown in FIG. It is a figure explaining the method to calculate the rotation angle of a main gear in the rotation angle detection apparatus which concerns on embodiment. It is a figure explaining the method of calculating the rotation angle of a subgear in the rotation angle detection apparatus which concerns on embodiment. It is a figure explaining the relationship of angle (theta) 1, (theta) 2, period T1, T2, period difference d, and rotation angle (PHI) in the case of (theta) 2 <= theta1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotation angle detection apparatus 2 Main gear 3 Sub gear 4 Main rotation detection mechanism 4a Ring-shaped magnet 4b, 4c Hall element 5, 7 Signal processing means 6 Sub rotation detection mechanism 6a Disk-shaped magnet 6b, 6c Hall element 8 Arithmetic processing means 9 Housing A1-A6 Amplifier L1-L12 Curve X Steering shaft

Claims (4)

A rotation angle detection device for detecting a rotation angle of a detected rotating body,
A main rotating body fixed to the detected rotating body and rotating together with the detected rotating body;
A sub-rotator that rotates at a predetermined rotation ratio with respect to the main rotor;
a main rotation detection mechanism that outputs a continuous signal that periodically changes according to the rotation of the main rotating body at a cycle number n per rotation, where n is an integer of 2 or more;
a sub-rotation detection mechanism that outputs a continuous signal that periodically changes according to the rotation of the sub-rotator at a frequency of m per rotation, where m is an integer that is smaller than n and equal to or greater than 1.
Signal processing means for calculating rotation angles of the main rotating body and the sub rotating body using continuous signals output from the main rotation detecting mechanism and the sub rotating detection mechanism;
The rotation angle of the main rotor body or sub rotatable body and the calculated, and the relative angles between the rotation angle and the angle of said multiplied by a predetermined rotation ratio of the rotation angle of the sub rotatable bodies of said main rotating body, the main Arithmetic processing means for calculating a rotation angle of the detected rotating body based on a rotation detection mechanism and a period of a continuous signal output by the sub rotation detection mechanism;
360 / n which is the period of the continuous signal of the main rotation detection mechanism is T1, and the period of 360 / m which is the period of the continuous signal of the sub-rotation detection mechanism is multiplied by G which is the predetermined rotation ratio. Assuming that 360 / m · G is T2 (T1 ≠ T2), the detection angle range of the rotation angle detection device is represented by R = T1 · T2 / | T1−T2 | having periodicity, and m is 1 A rotation angle detection device characterized by the above. The main rotation detection mechanism or the sub rotation detection mechanism is
A magnet that is attached to the main rotating body or the sub rotating body and generates a magnetic field whose intensity changes continuously and periodically in the rotation direction;
Two magnetic sensing elements arranged in the vicinity of the magnet so as to form a predetermined angle around the rotation center of the main rotating body or the sub rotating body;
The rotation angle detection device according to claim 1, comprising:   The rotation angle detection device according to claim 2, wherein the magnetic detection element is a Hall element.   The rotation angle detection device according to claim 2, wherein the magnetic detection element is a magnetoresistive element.

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