JP2016023980A - Absolute angle detection device, magnetic encoder of the same and angle detection magnetic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small magnetic rotational angle detector capable of detecting an absolute rotation angle with high resolution.SOLUTION: A rotary disk 1 is provided with: a track 10 for detecting a main angle in which a plurality of slits 10a are annularly arranged along a rotation direction; and a first track 11 for detecting an auxiliary angle in which a plurality of slits 11a are annularly arranged in an outer periphery of the track for detecting the main angle; and a second track 12 for detecting an auxiliary angle in which a plurality of slits 12a are annularly arranged in an inner periphery of the track for detecting the main angle. An angle detection magnetic sensor 3 has: a magnetic sensor 30 for detecting the main angle which has a bias magnet 2, and detects rotation of the track 10 for detecting the main angle; a first magnetic sensor 31 for detecting the auxiliary angle which detects rotation of the first track 11 for detecting the auxiliary angle; and a second magnetic sensor 32 for detecting the auxiliary angle which detects rotation of the second track 12 for detecting the auxiliary angle. The angle detection magnetic sensor is suitable for use for a magnetic encoder.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an absolute angle detection device, a magnetic encoder thereof, and an angle detection magnetic sensor, and more specifically, a thin film semiconductor magnetoresistive element having a thin film layer obtained by growing a semiconductor crystal on a substrate as an operation layer of a magnetosensitive portion. The present invention relates to an absolute angle detection device that uses a simple structure and achieves a small size and high resolution, a magnetic encoder thereof, and an angle detection magnetic sensor.

  In recent years, high resolution, high durability, and high reliability are required for encoders used for detecting the rotation angle of joints of machine tools and industrial robots. Optical encoders used so far in machine tools and industrial robots have achieved high resolution, but use optical components such as LEDs and photodetectors, so they are vulnerable to oil, dust, dust and heat. It is regarded as a problem.

For this reason, magnetic encoders having high durability and high reliability have begun to be used for encoders used in harsh environments where machine tools and industrial robots operate. In recent years, there has been an increasing demand for small and high-resolution magnetic encoders.
Conventionally, in a magnetic rotation angle detector, there is a method in which a magnetic slit obtained by processing a disk-shaped magnetic body into a slit shape is attached to a motor, and a magnetic field change accompanying the rotation of the magnetic slit is detected by a magnetic sensor.

For example, in Patent Document 1, in a magnetic encoder, a detection body is arranged between a magnetic slit plate and a flat magnet, and the detection body has a plurality of magnetoresistive elements in a circumferential shape having substantially the same diameter as the magnetic slit plate. Is described.
Further, for example, in Patent Document 2, a disk-shaped magnet magnetized so that the magnetic pole changes n times (n is an integer of 1 or more) for each rotation, and the magnet rotates together with the magnet for one rotation. A magnetic slit plate in which a portion having a high magnetic flux transmittance and a low portion are alternately repeated so that the magnetic flux transmittance changes m times each time (m is an integer of 2 or more, m> n), and the magnetic body A magnetic rotation angle detector including a magnetic sensor that detects magnetism from a magnet that has passed through a slit plate and a calculation unit that obtains the rotation angle of the magnet from the output of the second auxiliary angle detection sensor of the magnetic sensor is disclosed. ing.

  Further, for example, in Patent Document 3, the change in the output voltage amplitude of the magnetic sensor is reduced even when the rotating part made of a magnetic material is decentered with respect to the rotating shaft, and the detection accuracy of rotation of the rotating part is improved. In order to achieve this, the rotating unit includes a plurality of shape changing units along the circumferential direction of the rotating unit that cause a change in the distance to the magnetic sensor when the rotating unit rotates. A magnetic encoder that is arranged on a plane perpendicular to the axis of the rotating shaft so as to face the shape change portion in the thickness direction, and the bias magnet is magnetized in a direction parallel to the axis of the rotating shaft Is disclosed.

JP 2003-121200 A International Publication No. 2013/176104 (A1) JP 2013-185826 A

However, in Patent Document 1 described above, in order to detect an absolute rotation angle, it is necessary to provide signal tracks having a plurality of frequencies in a concentric manner on the magnetic slit plate, which increases the area of the rotation disc and detects rotation. There is a problem that the vessel becomes larger.
Further, in Patent Document 2 described above, a slit and a multipolar magnetized magnet are required, and the structure becomes complicated. Also, the accuracy of detection of the rotation angle was insufficient.

In Patent Document 3 described above, a rotation index signal can be obtained, but an absolute angle cannot be detected.
The present invention has been made in view of such problems, and an object of the present invention is to detect an absolute rotation angle with high resolution, and to provide a small absolute angle detection device, a magnetic encoder thereof, and an angle detection. It is to provide a magnetic sensor.

  The present invention has been made in order to achieve such an object. The invention according to claim 1 is directed to a disk-shaped magnetic body and includes a plurality of main angle detection slits (10a) annularly along the rotation direction. ) In which a main angle detection track (10) is arranged, and a plurality of first auxiliary angle detection slits (11a) are arranged in an annular shape on the outer periphery of the main angle detection track (10). An angle detection track (11) and a second auxiliary angle detection track in which a plurality of second auxiliary angle detection slits (12a) are annularly arranged on the inner periphery of the main angle detection track (10) ( 12), a bias magnet (2) disposed in the vicinity of the turntable (1), and the main magnet for detecting a magnetic field from the bias magnet (2). Provided in the area of the angle detection track (10) A first auxiliary angle detection sensor provided in the region of the first auxiliary angle detection track (11) for detecting the magnetic field from the angle detection magnetic sensor (30) and the bias magnet (2). A magnetic sensor (31) and a second auxiliary angle detection magnetic sensor (2) provided in the region of the second auxiliary angle detection track (12) for detecting the magnetic field from the bias magnet (2) 32), the second auxiliary angle detecting magnetic sensor (32) and the second auxiliary angle detecting magnetic sensor in order from the inner peripheral side along the radial direction of the rotating disk (1). An absolute angle detection device comprising a main angle detection magnetic sensor (30) and the first auxiliary angle detection magnetic sensor (31). (Figure 1, Figure 2, Figure 3)

According to a second aspect of the present invention, in the first aspect of the present invention, the main angle detection track (10) is configured to detect 2 ^{m + n} main angles in a ring shape along the rotation direction. A slit (10a) is arranged (m and n are integers greater than or equal to 1), and the second auxiliary angle detection track (11) is annularly arranged along the rotation direction with 2 ^{m + n} −1 number of the plurality of second One auxiliary angle detection slit (11a) is arranged. (Figure 2)
According to a third aspect of the present invention, in the second aspect of the present invention, the second auxiliary angle detection track (12) includes 2 ^{m + n} −2 ^{m of the} annular track along the rotation direction. A plurality of second auxiliary angle detection slits (12a) are arranged. (Figure 2)

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the main angle detecting magnetic sensor (30) is a circle of the main angle detecting track (10). The first auxiliary angle detection magnetic sensor (31) is arranged above or below the circumference, and is arranged above or below the circumference of the first auxiliary angle detection track (11). The second auxiliary angle detection magnetic sensor (32) is arranged above or below the circumference of the second auxiliary angle detection track (12). (Figure 3)

The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the bias magnet (2) includes the main angle detection magnetic sensor (30) and the first angle sensor. The auxiliary angle detection magnetic sensor (31) and the second auxiliary angle detection magnetic sensor (32) are disposed on the opposite side of the rotating disk (1). (Figure 3)
The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the angle detection magnetic sensor (3) is a semiconductor magnetoresistive element.

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the angle detection magnetic sensor (3) is connected to the rotating disk (1) via a shaft (4). The first auxiliary angle detecting semiconductor magnetoresistive element, the main angle detecting semiconductor magnetoresistive element, and the second auxiliary angle detecting semiconductor magnetoresistive element are juxtaposed on the fixed plate (5) provided in this order. It is a magnetic sensor.

The invention according to claim 8 is the invention according to any one of claims 1 to 7, wherein each of the plurality of slits (10a, 11a, 12a) is directed from the inner diameter side toward the outer diameter side. It is characterized by a trapezoidal shape with a wide width.
The invention according to claim 9 is the invention according to claim 8, wherein the first auxiliary angle detecting semiconductor magnetoresistive element, the main angle detecting semiconductor magnetoresistive element, and the second auxiliary angle detecting. In the order of the semiconductor magnetoresistive elements for use, the width of the magnetically sensitive portion of the semiconductor magnetoresistive elements is narrow.

According to a tenth aspect of the present invention, in the invention according to the ninth aspect, in the semiconductor magnetoresistive element, a radial length of the magnetically sensitive portion is d, and each of the rotating discs (1) is When the length in the radial direction of the slits (10a, 11a, 12a) is W, the ratio W / d is 1 or more. (Fig. 8)
The invention described in claim 11 is the invention described in claim 10, wherein the W / d is 2 or more.

According to a twelfth aspect of the present invention, in the semiconductor magnetoresistive element according to any one of the ninth to eleventh aspects, the semiconductor magnetoresistive element includes a thin film layer formed by growing a semiconductor crystal on a substrate. It is a thin film semiconductor magnetoresistive element used as an operation layer.
The invention according to claim 13 is the invention according to any one of claims 9 to 11, wherein each of the slits (10a) with respect to the radial center of each of the slits (10a, 11a, 12a). , 11a, 12a), the radial center of the semiconductor magnetoresistive element is shifted outward in the radial direction. (Fig. 8)
According to a fourteenth aspect of the present invention, there is provided a magnetic encoder comprising the rotating disk absolute angle detecting device according to any one of the first to thirteenth aspects.

  According to a fifteenth aspect of the present invention, a main angle detecting magnetic sensor (30) for detecting a main angle of the rotating disk (1) and a first auxiliary angle for detecting the first auxiliary angle of the rotating disk (1). The auxiliary angle detecting magnetic sensor (31) and the main angle detecting magnetic sensor (30) are disposed on the opposite side of the first auxiliary angle detecting magnetic sensor (31). Based on the second auxiliary angle detection magnetic sensor (32) for detecting the second auxiliary angle of the panel (1), and the main angle, the first auxiliary angle, and the second auxiliary angle. The angle detection magnetic sensor is characterized in that the absolute angle of the rotating disk (1) is detected based on the principle described above.

According to a sixteenth aspect of the present invention, the main angle detecting magnetic sensor (30), the first auxiliary angle detecting magnetic sensor (31), and the second auxiliary in the invention according to the fifteenth aspect. The magnetic sensing part of the angle detection magnetic sensor (32) has a rectangular shape,
In the order of the first auxiliary angle detection magnetic sensor (31), the main angle detection magnetic sensor (30), and the second auxiliary angle detection magnetic sensor (32), the long side of the magnetic sensing portion is short. It is comprised so that it may become.

According to a seventeenth aspect of the present invention, in the invention of the fifteenth or sixteenth aspect, the output signal of the main angle detecting magnetic sensor (30) and the first auxiliary angle detecting magnetic sensor (31). A first vernier caliper (21) for calculating a first difference from the output signal; an output signal from the main angle detection magnetic sensor (30); and a second auxiliary angle detection magnetic sensor (32). A second caliper calculating unit (22) for calculating a second difference from the output signal, and the output signal of the first caliper calculating unit (21) and the second caliper calculating unit (22). The absolute angle of the rotating disk (1) is detected based on the output signal and the output signal of the main angle detection magnetic sensor (30). (Fig. 7)
The invention according to claim 18 is the invention according to any one of claims 15 to 17, wherein the first auxiliary angle detecting magnetic sensor (31) is provided on the fixed platen (5). The main angle detecting magnetic sensor (30) and the second auxiliary angle detecting magnetic sensor (32) are arranged in parallel and packaged. (Fig. 10 (a))

  According to the present invention, an absolute rotation angle can be detected with high resolution, and a small absolute angle detection device, its magnetic encoder, and angle detection magnetic sensor can be realized.

1 is an overall configuration diagram for explaining an embodiment of an absolute angle detection device according to the present invention. FIG. 2 is a top view of the rotating disk shown in FIG. 1 and a cross-sectional view of a shaft. It is a figure for demonstrating the positional relationship of each magnetic sensor corresponding to each track | truck shown in FIG.1 and FIG.2. (A) And (b) is a figure which shows the positional relationship of the slit of a turntable, a bias magnet, and a magnetic sensor, and the magnetic flux which comes out of a bias magnet. It is a figure which shows the output voltage signal of each angle detection magnetic sensor in two cycles of the track for main angle detection. (A) thru | or (c) is a figure which shows the output signal of each magnetic sensor in one rotation of a turntable. It is a block diagram for demonstrating the signal processing in the magnetic sensor for angle detection which concerns on this invention. It is a figure which shows the positional relationship of a slit and the magnetic sensing part of a semiconductor magnetoresistive element. (A) to (c) show the output voltage amplitude with respect to the ratio W / d between the radial length W of the slit shown in FIG. 8 and the radial length d of the magnetic sensitive portion of the semiconductor magnetoresistive element. It is a figure which shows the graph which shows the relationship between a change rate and an output voltage amplitude, and the graph of the output voltage amplitude with respect to XY. (A) And (b) is a figure which shows the packaging state of an angle detection magnetic sensor.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall configuration diagram for explaining an embodiment of an absolute angle detection device according to the present invention. In the figure, reference numeral 1 is a rotating disk, 2 is a bias magnet, 3 is an angle detection magnetic sensor, 4 is a shaft, and 5 is a stationary disk (substrate).
The embodiment of the present invention includes a shaft 4, a magnetic rotating plate 1 fixed to the shaft 4, an angle detection magnetic sensor 3 and a bias magnet 2 provided on the fixed plate 5.

Further, the rotating disk 1 is fixed so as to be perpendicular to the central axis of the shaft 4 serving as a rotating shaft. The rotating disk 1 is configured to rotate in synchronism with the rotating shaft via a bearing with respect to the shaft 4 serving as the rotating shaft.
In addition, a fixed platen 5 is disposed so as to be separated from the rotating plate 1 in the vertical direction. The fixed platen 5 is fixed without rotating with respect to the rotary platen 1. An angle detection magnetic sensor 3 is arranged on the stationary platen 5 on the rotating plate 1 side, and a bias magnet 2 is arranged on the opposite side.
In the present embodiment, the rotating disk 1 is configured such that a slit is formed in a disk-shaped magnetic body, and the angle detection magnetic sensor 3 detects a magnetic field change accompanying the rotation of the rotating disk 1.

FIG. 2 is a top view of the rotating disk shown in FIG. 1 and a cross-sectional view of the shaft. In the figure, reference numeral 10 denotes a main angle detection track, 10a denotes a main angle detection slit, 11 denotes a first auxiliary angle detection track, 11a denotes a first auxiliary angle detection slit, and 12 denotes a second auxiliary angle detection. A track 12a indicates a second auxiliary angle detection slit.
The rotating disk 1 includes a main angle detecting track 10 in which a plurality of main angle detecting slits 10a are arranged in a circular shape along a rotation direction on a disk-shaped magnetic body, and an annular outer periphery of the main angle detecting track 10. A plurality of first auxiliary angle detection tracks 11a having a plurality of first auxiliary angle detection slits 11a disposed therein, and a plurality of second auxiliary angle detection slits 12a annularly formed on the inner periphery of the main angle detection track 10. Is provided with a second auxiliary angle detection track 12. The bias magnet 2 is disposed in the vicinity of the turntable 1.

The main angle detection track 10 has, for example, 2 ^{m + n} main angle detection slits 10 a arranged in a ring shape along the rotation direction (m and n are integers of 1 or more), and the first auxiliary angle detection track 11. However, 2 ^{m + n} −1 first auxiliary angle detection slits 11 a are arranged in a ring shape along the rotation direction. Thereby, the angle can be detected with high accuracy by the caliper principle.
The second auxiliary angle detection track 12 is provided with 2 ^{m + n} −2 ^m second auxiliary angle detection slits 12 a in a ring shape along the rotation direction. As a result, the main angle detection track 10 and the second auxiliary angle detection track 12 detect the angles with ²ⁿ and ^2n-1 calipers, and therefore there is no second auxiliary angle detection track 12. In this case, an allowable amount for an electrical phase shift between the output voltage from the main angle detection magnetic sensor and the output voltage from the first auxiliary angle detection magnetic sensor is increased.

  In addition, it is preferable that the plate | board thickness of the disk shaped magnetic body which comprises the rotating disk 1 shall be 0.4 mm or more and 1.0 mm or less. If the plate thickness is 0.4 mm or more, surface bias can be suppressed by the attractive force of the bias magnet 2 and the envelope of the output voltage amplitude can be made uniform. On the other hand, if the plate thickness is 1.0 mm or less, the corner R becomes 0.5 mm or more when the slit is formed by photoetching, and the output voltage amplitude drop due to the corner R can be suppressed.

The second auxiliary angle detection track 12 is provided with 2 ^{m + n} −2 ^m plural second auxiliary angle detection slits 12 a in an annular shape along the rotation direction. Each of the plurality of slits 10a, 11a, and 12a described above has a trapezoidal shape in which the width in the circumferential direction increases from the inner diameter side toward the outer diameter side.
Moreover, the absolute angle detection device for a rotary disk described above can be used for a magnetic encoder.

FIG. 3 is a diagram for explaining the positional relationship between the magnetic sensors corresponding to the tracks shown in FIGS. 1 and 2. In the figure, reference numeral 30 denotes a main angle detection magnetic sensor, 31 denotes a first auxiliary angle detection magnetic sensor, and 32 denotes a second auxiliary angle detection magnetic sensor.
The angle detection magnetic sensor 3 detects the magnetic field from the bias magnet 2 and the main angle detection magnetic sensor 30 provided in the region of the main angle detection track 10 in order to detect the magnetic field from the bias magnet 2. The first auxiliary angle detecting magnetic sensor 31 provided in the region of the first auxiliary angle detecting track 11 and the second auxiliary angle detecting track 12 for detecting the magnetic field from the bias magnet 2 are provided. And a second auxiliary angle detecting magnetic sensor 32 provided in the region.

A second auxiliary angle detection magnetic sensor 32, a main angle detection magnetic sensor 30, and a first auxiliary angle detection magnetic sensor 31 are arranged in this order from the inner peripheral side along the radial direction of the fixed platen 5. Yes.
In addition, the main angle detection magnetic sensor 30 is disposed above or below the main angle detection track 10 so as to correspond to the tracks 10, 11, and 12, and the first auxiliary angle detection magnetic sensor 31 is The first auxiliary angle detection track 11 is arranged above or below the circumference, and the second auxiliary angle detection magnetic sensor 32 is arranged above or below the second auxiliary angle detection track 12. Yes.
In addition, the bias magnet 2 is provided on the rotating plate 1 with a main angle detection magnetic sensor 30, a first auxiliary angle detection magnetic sensor 31, and a second auxiliary angle detection magnetic sensor 32 provided on the fixed plate 5. It is arranged on the opposite side.

The angle detection magnetic sensor 3 is preferably a semiconductor magnetoresistive element. On the stationary platen 5 provided on the rotating plate 1 via the shaft 4, the first auxiliary angle detection semiconductor magnetoresistive device and the main magnetoresistive element are arranged. The angle detecting semiconductor magnetoresistive element and the second auxiliary angle detecting semiconductor magnetoresistive element are arranged in this order.
Further, the width of the magnetic sensing portion of the semiconductor magnetoresistive element becomes wider in the order of the first auxiliary angle detecting semiconductor magnetoresistive element, the main angle detecting semiconductor magnetoresistive element, and the second auxiliary angle detecting semiconductor magnetoresistive element. ing. The semiconductor magnetoresistive element is preferably a thin film semiconductor magnetoresistive element having a thin film layer obtained by growing a semiconductor crystal on a substrate as an operating layer of the magnetosensitive portion.

FIGS. 4A and 4B are diagrams showing the positional relationship between the slit of the rotating disk, the bias magnet, and the magnetic sensor, and the magnetic flux emitted from the bias magnet.
The main angle detection magnetic sensor 30 detects the main angle of the rotation angle as an electrical signal corresponding to the main angle detection track 10. The first auxiliary angle detection magnetic sensor 31 detects the first auxiliary angle of the rotation angle as an electrical signal corresponding to the first auxiliary angle detection track 11. The second auxiliary angle detection magnetic sensor 32 detects the second auxiliary angle of the rotation angle as an electrical signal corresponding to the second auxiliary angle detection track 12.

As shown in FIG. 4A, when the slit 1 a comes on the angle detection magnetic sensor 3, the magnetic flux emitted from the bias magnet 2 increases from the N pole and enters the S pole, and the angle detection magnetic sensor 3. Less magnetic flux enters.
On the other hand, as shown in FIG. 4B, when the magnetic metal part 1b comes on the angle detection magnetic sensor 3 (not the slit 1a), the magnetic field output from the bias magnet 2 attracts the magnetic substance. Therefore, the magnetic flux density is larger than that in FIG.
Due to the change in magnetic flux density input to the angle detection magnetic sensor 3, the angle detection magnetic sensor 3 provides a sine wave output voltage signal.

  FIG. 5 is a diagram showing the output voltage signal of each angle detection magnetic sensor in two cycles of the main angle detection track. Each angle when the turntable 1 is rotated when m = 2 and n = 3. The output signals of the detection magnetic sensors 30, 31, 32 are shown. The angle of the abscissa is that of each magnetic sensor in the rotating disk 1 when one period from the main angle detection slit of the main angle detection track 10 to the adjacent main angle detection slit is 360 degrees (electrical angle). It represents the output voltage signal.

  As shown in FIG. 5, the output voltage signal of the first auxiliary angle detection magnetic sensor 31 corresponds to the first auxiliary angle detection track 11, and the sine wave output voltage signal of the main angle detection magnetic sensor 30. The waveform is out of phase with respect to. The output signal of the second auxiliary angle detection magnetic sensor 32 is out of phase with the sine wave output voltage signal of the main angle detection magnetic sensor 30 corresponding to the second auxiliary angle detection track 12. Waveform.

  FIGS. 6A to 6C are diagrams showing output voltage signals of each magnetic sensor in one rotation of the rotating disk, and FIG. 6A is an output voltage of the magnetic sensor for detecting the main angle in one rotation of the rotating disk. FIG. 6B shows the output voltage signal of the first auxiliary angle detecting magnetic sensor for one rotation of the rotating disk, and FIG. 6C shows the second auxiliary angle detecting magnetism for one rotation of the rotating disk. The sensor output voltage signal is shown.

That is, it is an output voltage signal of each angle detection magnetic sensor 30, 31, 32 when the turntable 1 is rotated once when m = 2 and n = 3. The angle on the horizontal axis represents the output voltage signal of each angle detecting magnetic sensor 30, 31, 32 when the rotation of the turntable 1 is 360 degrees (mechanical angle).
The output voltage signal of the main angle detection magnetic sensor 31 outputs 32 (2 ⁵ ) sine waves while the turntable 1 rotates once. The output voltage signal of the first auxiliary angle detection magnetic sensor 31 outputs 31 (2 ⁵ -1) sine waves while the turntable 1 makes one rotation. The output signal of the second auxiliary angle detection magnetic sensor 32 outputs 28 (2 ⁵ -2 ² ) sine waves while the turntable 1 makes one rotation.

  FIG. 7 is a block diagram for explaining signal processing in the magnetic sensor for angle detection according to the present invention, and shows an example of a block diagram for calculating the absolute angle of the rotating disk from the output voltage of each magnetic sensor. In the figure, reference numeral 20 denotes an electric interpolation unit, 21 denotes a first caliper calculation unit, 22 denotes a second caliper calculation unit, and 23 denotes an absolute angle calculation unit. Components having the same functions as those in FIGS. 1 to 3 are denoted by the same reference numerals.

The first caliper computing unit 21 takes the first difference between the output voltage signal of the main angle detection magnetic sensor 30 and the output voltage signal of the first auxiliary angle detection magnetic sensor 31 according to the caliper principle, and 2 ^{m + n} Calculate the accuracy of.
Further, the second caliper calculation unit 22 takes the second difference between the output voltage signal of the main angle detection magnetic sensor 32 and the output voltage signal of the second auxiliary angle detection magnetic sensor 32 according to the caliper principle, 2. Calculate with ⁿ precision.

Further, the electrical interpolation unit 20 electrically interpolates the output voltage signal of the main angle detection magnetic sensor 30 and outputs it as an electrical angle. The total resolution of the angle output is the number of main angle detection slits when the electrical angle resolution obtained by electrically interpolating the output signal of the main angle detection magnetic sensor 30 is 2 ^l (l is an integer of 1 or more). Multiplication of 2 ^{m + n} , that is, 2 ^{l + m + n} .
The absolute angle calculation unit 23 adds the second caliper angle calculation result and the first caliper calculation processing result, and outputs the output voltage signal of the main angle detection magnetic sensor 30 and the first auxiliary angle detection magnetism. It is possible to increase the allowable value of the electrical angle phase difference with respect to the output voltage signal of the sensor 31.

The angle detection magnetic sensor 3 according to the present invention includes a main angle detection magnetic sensor 30 that detects a main angle of the rotating disk 1 and a first auxiliary angle detection that detects a first auxiliary angle of the rotating disk 1. A second auxiliary angle for detecting the second auxiliary angle of the turntable 1 disposed on the opposite side of the first auxiliary angle detecting magnetic sensor 31 with the magnetic sensor 31 and the main angle detecting magnetic sensor 30 interposed therebetween. Based on the magnetic sensor 32 for auxiliary angle detection, the main angle, the first auxiliary angle, and the second auxiliary angle, the absolute angle of the rotating disk 1 is detected by the caliper principle.
In the angle detection magnetic sensor 3, the magnetic sensing parts of the main angle detection magnetic sensor 30, the first auxiliary angle detection magnetic sensor 31, and the second auxiliary angle detection magnetic sensor 32 have a rectangular shape. The first auxiliary angle detection magnetic sensor 31, the main angle detection magnetic sensor 30, and the second auxiliary angle detection magnetic sensor 32 are arranged in this order so that the long side of the magnetic sensing portion becomes shorter.

FIG. 8 is a diagram showing the positional relationship between the slit and the magnetic sensitive part of the semiconductor magnetoresistive element.
The length in the radial direction of the slit (the void portion of the rotating disk, that is, the hole) is W, and the radial length of the magnetically sensitive portion of each angle detection magnetic sensor is d. Of the length W in the radial direction of the slit, the length on the inner diameter side excluding the length d of each angle detection magnetic sensor is X, and the length on the outer diameter side is Y.
That is, in a semiconductor magnetoresistive element which is a kind of magnetic sensor, when the radial width of the magnetic sensing portion is d and the radial length of each slit 10a, 11a, 12a of the rotating disk 1 is W, The ratio W / d is preferably 1 or more. Moreover, it is preferable that W / d is 2 or more.
Further, the radial center of the semiconductor magnetoresistive element facing each slit 10a, 11a, 12a is shifted radially outward with respect to the radial center of each slit 10a, 11a, 12a. .

  FIGS. 9A to 9C show the output with respect to the ratio W / d between the radial length W of the slit shown in FIG. 8 and the radial length d of the magnetic sensitive portion of the semiconductor magnetoresistive element. It is a figure which shows the graph which shows the relationship between a voltage amplitude change rate and an output voltage amplitude, and the graph of the output voltage amplitude with respect to XY. FIG. 9A is a diagram showing the relationship of the output voltage amplitude change rate with respect to W / d when the encoder has an eccentricity of ± 100 μm, and FIG. 9B is a diagram showing the relationship of the output voltage amplitude with respect to W / d. FIG. 9C is a diagram showing the relationship between XY, which is the difference between X and Y shown in FIG. 8, and the output voltage amplitude.

In FIG. 9A, the output voltage amplitude change rate when the encoder eccentricity is ± 100 μm is the rotation of the rotating plate of the semiconductor magnetoresistive element caused by eccentricity of the rotating plate (deviation from the central axis of rotation). It is the ratio between the maximum value and the minimum value of the output voltage amplitude. Examples of the eccentricity include a deviation between the rotation center of the slit of the rotating disk and the center of the hole for the shaft, and a center axis deviation generated when the rotating disk is assembled to the shaft constituting the rotation axis.
If the output voltage amplitude change rate is within about 10%, the angle can be calculated with high precision by the arithmetic processing circuit, and it is preferable that W / d is 1 or more as shown in FIG. If W / d is 2 or more, the rate of change of the output voltage of the angle detection semiconductor magnetoresistive element is within 5%, and the angle can be calculated with higher accuracy.

  In FIG. 9B, when W / d is increased, when the slit position is in the above-described FIG. 4A, that is, when the slit 1a comes on the semiconductor magnetoresistive element 3, the bias magnet 2 moves away. More magnetic flux exits from the N pole and enters the S pole, and less magnetic flux enters the magnetic flux of the angle detection magnetic sensor. Therefore, the difference in magnetic flux density between the metal portion and the slit (the gap portion of the rotating disk, that is, the hole portion) becomes larger, and the output voltage amplitude becomes larger.

As shown in FIG. 9B, when W / d is 3 or more, a sufficient output voltage amplitude of the semiconductor magnetoresistive element can be secured, and the output voltage amplitude that can be accurately processed by the subsequent processing circuit. Can be secured.
To summarize the above, the output change rate due to eccentricity and the length W in the radial direction of the slit (the gap portion of the rotating disk, that is, the hole portion) and the length d in the radial direction of the semiconductor magnetoresistive element and In view of the magnitude of the output voltage amplitude, it is preferable that W / d is 1 or more, more preferably 2 or more, and further preferably 3 or more.

In FIG. 9C, in order to maximize the output voltage amplitude, the center position in the radial direction of the semiconductor magnetoresistive element is on the outer diameter side (X−Y) with respect to the central portion (XY = 0) in the radial direction of the slit hole. Y> 0) is preferred.
This is because the disk has a curvature, so the shape of the slit hole is not a rectangle, but a trapezoid whose width increases from the inner diameter side to the outer diameter side, so the slit width is wider on the outer diameter side than on the inner diameter side. Therefore, as described above, the change in magnetic flux density between the metal portion and the slit is increased, and the maximum value of the output voltage amplitude is larger than the central portion (X−Y = 0) in the radial direction of the slit hole (X− Y> 0).

  FIGS. 10A and 10B are views showing the packaging state of the angle detection magnetic sensor, and FIG. 10A is an example of the angle detection magnetic sensor. The first auxiliary angle detection magnetic sensor 31 is shown in FIG. , The main angle detection magnetic sensor 30 and the second auxiliary angle detection magnetic sensor 32 are juxtaposed on one chip and packaged. FIG. 10B shows each angle detection magnetic sensor. It is a figure which shows the form which uses three things packaged separately. In the figure, reference numerals 3a, 3b and 3c denote chips on which angle detection magnetic sensors are arranged, and 6a, 6b and 6c denote packages.

  In the present embodiment, each angle detecting magnetic sensor is preferably a thin film semiconductor magnetoresistive element having a thin film layer obtained by growing a semiconductor crystal on a substrate as an operating layer of the magnetic sensitive portion. In order to realize a small magnetic encoder, it is better to reduce the value of W described above. In that case, in order to keep the value of W / d above a certain value, it is necessary to reduce the radial length d of the magnetically sensitive portion of the semiconductor magnetoresistive element. In order to suppress the amount of heat generated by the semiconductor magnetoresistive element, it is necessary to set the resistance value to a certain value or more. In order to reduce d while maintaining the resistance value, it is necessary to increase the sheet resistance value of the semiconductor magnetoresistive element, and this is preferably a thin film semiconductor magnetoresistive element. Further, in order to detect the absolute angle of the rotating disk 1 with high accuracy, it is important to make the output voltage from the magnetic sensor as close as possible to the sine wave or cosine wave as in the present embodiment, that is, the output voltage. The magnetic sensor is preferably a semiconductor magnetoresistive element in order to reduce the distortion as much as possible.

  In the present embodiment, the first auxiliary angle magnetic sensor 31, the main angle detection magnetic sensor 30, and the second auxiliary angle magnetic sensor 32 are arranged in parallel on one chip. The configuration in which the main angle detection magnetic sensor 30 is arranged in the middle and the auxiliary angle magnetic sensors 31 and 32 are arranged on both sides of the main angle detection magnetic sensor 30 is the main angle of the angle θ deviation that occurs when the chip is lead frame die bonded. The influence on the electrical phase shift between the output voltage from the detection magnetic sensor and the output voltage from the auxiliary angle detection magnetic sensor can be reduced. In other words, by placing the main angle detection magnetic sensor 30 that is the center of the subsequent calculation processing in the center, the phase shift of the output voltage due to the angle shift at the time of die bonding can be reduced, and the influence on the subsequent calculation processing is reduced. It can be reduced.

Further, as shown in FIG. 10 (b), each of the angle detection magnetic sensors separately packaged in a three-sided form mounted on a substrate is used, as shown in FIG. 10 (a). A form in which an angle detection magnetic sensor arranged in parallel on one chip is packaged and used is preferable from the viewpoint of an electrical phase shift of an output voltage from each angle detection magnetic sensor.
By implementing a plurality of angle detection magnetic sensors on one chip as an angle detection magnetic sensor corresponding to a plurality of angle detection track slits, output voltages from the plurality of angle detection magnetic sensors are realized. For the electrical phase shift between them, only the angle θ shift during die bonding should be considered.
Also, by optimizing the distance D = W + S between the angle detection magnetic sensors (where S is the distance between the radial slits), the electrical phase between the output voltages from the plurality of angle detection magnetic sensors. The deviation Dsinθ can be set to an optimum value.

DESCRIPTION OF SYMBOLS 1 Rotating disk 1a Slit 1b Metal part 2 Bias magnet 3, 3a, 3b, 3c Angle detection magnetic sensor 4 Shaft 5 Fixed board (board | substrate)
6 Package 6a, 6b, 6c Package 10 Main angle detection track 10a Main angle detection slit 11 First auxiliary angle detection track 11a First auxiliary angle detection slit 12 Second auxiliary angle detection track 12a Second Auxiliary angle detection slit 20 Electric interpolation section 21 First caliper calculation section 22 Second caliper calculation section 23 Absolute angle calculation section 30 Main angle detection magnetic sensor 31 First auxiliary angle detection magnetic sensor 32 Second Magnetic sensor for auxiliary angle detection

Claims (18)

A main angle detection track in which a plurality of main angle detection slits are annularly arranged along the rotation direction in a disk-like magnetic body, and a plurality of first auxiliary angles in an annular shape on the outer periphery of the main angle detection track A first auxiliary angle detection track in which detection slits are arranged, and a second auxiliary angle detection track in which a plurality of second auxiliary angle detection slits are arranged annularly on the inner periphery of the main angle detection track. A turntable provided with a track;
A bias magnet disposed in the vicinity of the turntable;
A main angle detection magnetic sensor provided in a region of the main angle detection track for detecting the magnetic field from the bias magnet, and the first auxiliary angle detection for detecting the magnetic field from the bias magnet. A first auxiliary angle detection magnetic sensor provided in the track area and a second auxiliary angle detection magnetic sensor provided in the second auxiliary angle detection track area for detecting the magnetic field from the bias magnet. An angle detection magnetic sensor having an auxiliary angle detection magnetic sensor,
The second auxiliary angle detecting magnetic sensor, the main angle detecting magnetic sensor, and the first auxiliary angle detecting magnetic sensor are arranged in this order from the inner peripheral side along the radial direction of the rotating disk. Angle detection device. A plurality of 2 ^{m + n} main angle detection slits (m and n are integers of 1 or more) are arranged in a ring shape along the rotation direction on the main angle detection track, and the first auxiliary angle detection 2. The absolute angle detection device according to claim 1, wherein 2 ^{m + n} −1 of the plurality of first auxiliary angle detection slits are annularly arranged along the rotation direction in the track. 3. The absolute angle according to claim 2, wherein the second auxiliary angle detection track has 2 ^{m + n} −2 ^m of the plurality of second auxiliary angle detection slits arranged in a ring shape along the rotation direction. Detection device. The main angle detection magnetic sensor is arranged above or below the circumference of the main angle detection track,
The first auxiliary angle detection magnetic sensor is disposed above or below the circumference of the first auxiliary angle detection track,
The absolute angle detection according to any one of claims 1 to 3, wherein the second auxiliary angle detection magnetic sensor is arranged above or below the circumference of the second auxiliary angle detection track. apparatus.   The bias magnet is disposed on the opposite side of the rotating disk with the main angle detection magnetic sensor, the first auxiliary angle detection magnetic sensor, and the second auxiliary angle detection magnetic sensor in between. The absolute angle detection device according to any one of 1 to 4.   The absolute angle detection device according to any one of claims 1 to 5, wherein the angle detection magnetic sensor is a semiconductor magnetoresistive element.   The angle detection magnetic sensor includes a first auxiliary angle detection semiconductor magnetoresistive element, a main angle detection semiconductor magnetoresistive element, and a second auxiliary angle detection on a fixed plate provided on the rotating plate via a shaft. The absolute angle detection device according to any one of claims 1 to 6, which is a magnetic sensor arranged in the order of the semiconductor magnetoresistive elements for use.   The absolute angle detection device according to any one of claims 1 to 7, wherein each of the plurality of slits has a trapezoidal shape whose width increases from the inner diameter side toward the outer diameter side.   In the order of the first auxiliary angle detecting semiconductor magnetoresistive element, the main angle detecting semiconductor magnetoresistive element, and the second auxiliary angle detecting semiconductor magnetoresistive element, the width of the magnetic sensitive portion of the semiconductor magnetoresistive element is The absolute angle detection device according to claim 8, which is narrow.   In the semiconductor magnetoresistive element, when the length in the radial direction of the magnetic sensing portion is d and the length in the radial direction of each slit of the rotating disk is W, the ratio W / d is: The absolute angle detection device according to claim 9, wherein the absolute angle detection device is one or more.   The absolute angle detection device according to claim 10, wherein the W / d is 2 or more.   12. The absolute angle detection according to claim 9, wherein the semiconductor magnetoresistive element is a thin film semiconductor magnetoresistive element having a thin film layer obtained by growing a semiconductor crystal on a substrate as an operation layer of a magnetosensitive portion. apparatus.   The absolute angle according to any one of claims 9 to 11, wherein a radial center of the semiconductor magnetoresistive element facing each slit is shifted outward in a radial direction with respect to a radial center of each slit. Detection device.   A magnetic encoder comprising the absolute angle detection device according to any one of claims 1 to 13. A main angle detection magnetic sensor for detecting the main angle of the turntable;
A first auxiliary angle detecting magnetic sensor for detecting a first auxiliary angle of the rotating disk;
A second auxiliary angle detection magnet for detecting a second auxiliary angle of the rotating disk, which is disposed on the opposite side of the first auxiliary angle detection magnetic sensor with the main angle detection magnetic sensor interposed therebetween. A sensor,
An angle detection magnetic sensor that detects an absolute angle of the rotating disk based on the caliper principle based on the main angle, the first auxiliary angle, and the second auxiliary angle. The magnetic sensitive portions of the main angle detection magnetic sensor, the first auxiliary angle detection magnetic sensor, and the second auxiliary angle detection magnetic sensor are rectangular,
The long side of the magnetic sensing portion is configured to be shorter in the order of the first auxiliary angle detection magnetic sensor, the main angle detection magnetic sensor, and the second auxiliary angle detection magnetic sensor. 15. An angle detection magnetic sensor according to 15. A first caliper calculating unit that calculates a first difference between an output signal of the main angle detection magnetic sensor and an output signal of the first auxiliary angle detection magnetic sensor;
A second caliper calculating unit that calculates a second difference between the output signal of the main angle detection magnetic sensor and the output signal of the second auxiliary angle detection magnetic sensor;
The absolute angle of the rotating disk is detected based on an output signal of the first caliper calculating unit, an output signal of the second caliper calculating unit, and an output signal of the main angle detecting magnetic sensor. The angle detection magnetic sensor according to 15 or 16.   18. The package according to claim 15, wherein the first auxiliary angle detection magnetic sensor, the main angle detection magnetic sensor, and the second auxiliary angle detection magnetic sensor are juxtaposed on the fixed plate in order. The angle detection magnetic sensor as described in any one of Claims.

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