JPH10260059A - Magnetic scale and magnetic type detecting device having it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form magnetic field distribution at magnetic pole end parts into a rectangular shape so as to accurately detect displacement by constituting a magnetic field generating means of a center magnetic pole row consisting of one magnetic pole of N-pole or S-pole, and magnetic pole rows consisting of the other magnetic pole on both sides of the former. SOLUTION: This magnetic scale 10 moves integratedly with an object to be detected in displacement, and it can be relatively displaced against a sensor head 20. A magnetic field generating means is constituted of a center magnetic pole row 12, and magnetic pole rows 13, 14 on both sides of the former, and in the center magnetic pole row 12, magnetic poles 12a having one polarity of Npole or S-pole are arranged in the fixed displacement direction at regular pitches. In the magnetic pole rows 13, 14 on both sides, magnetic poles 13a, 14a having the other polarity of the respective N-pole or S-pole are arranged at the same pitches as the magnetic poles 12a. Hereby, difference of magnetic field intensity on the magnetic pole and between the magnetic poles is made clear, the magnetic field intensity detecting level at the magnetic pole end part can be made into a rectanglar shape, and the magnetic scale capable of accurately detecting positioin is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic scale and a magnetic detection device provided with the same, and more particularly to a magnetic scale suitable for detecting displacement, such as an encoder, and using the magnetic scale in a predetermined displacement direction. The present invention relates to a magnetic detection device that detects displacement, velocity, angular velocity, and the like.

[0002]

2. Description of the Related Art In a displacement detector such as a magnetic encoder having a magnetic scale, a coded magnetic pattern is provided on the surface of the magnetic scale in order to take out a displacement of the magnetic scale with respect to a sensor head as a signal. . The main form of the signal code is, for example, the following (1),
It is like (2). (1) Incremental code At least two rows of fixed-period magnetic patterns are arranged and a phase difference is provided between the two magnetic patterns to detect a displacement direction, and the position, angle, and speed are set as incremental codes provided with one origin reference. , Acceleration and the like can be detected. (2) Absolute code In the case of a gray code or a BCD code as a representative example, magnet rows having different magnetic pole lengths in the scale displacement direction are arranged in parallel in a direction substantially orthogonal to the displacement direction, so-called absolute position.
Performs angle, velocity, and acceleration detection.

[0003]

However, in such a conventional position detection using a magnetic scale,
When the pitch between the magnetic poles arranged in a certain polar arrangement (for example, NNN,..., NSSN,...) Is small, a magnetic field intensity sub-peak occurs between the magnetic poles or a magnetic field intensity sufficient on the magnetic poles (displacement detection direction). Stable detection was not possible because the obtained region was too short.

When the magnetic pole length in the displacement detection direction increases with the expansion of the length measurement range, for example, as shown by a solid line B in FIG. Even if the threshold level slightly fluctuates in a comparator or the like in the electric signal processing circuit, the amount of deviation of the detection position becomes large, so that stable and accurate position detection cannot be performed.

For these reasons, in the conventional absolute type magnetic detection method, the length measurement range is limited so that the magnetic pole length is within a predetermined range. By disposing a plurality of magnetic patterns similar to 1) in parallel and providing a phase difference between them, a displacement direction is detected, and positional information obtained from the magnetic patterns is sequentially stored in a memory in the electric signal processing circuit. Therefore, a pseudo-absolute type that detects an absolute position is adopted.

However, even in this pseudo-absolute type magnetic detection system, if a position change occurs on the magnetic scale after a power failure due to some kind of failure and before the recovery, it is stored in the memory. Since the position corresponding to the position information that has been set is different from the actual scale position at the time of return, a detection error may occur after the return.

As described above, in the conventional magnetic detection method, it has been difficult to perform displacement detection (position, velocity or angular velocity in a linear or rotational direction) with a large length measurement range. Therefore, the present invention has as its first object to provide a magnetic scale capable of making the magnetic field distribution at the magnetic pole end rectangular regardless of the magnetic pole length. It is a second object to provide a magnetic detection device capable of detecting displacement accurately.

[0008]

In order to achieve the above object, a first aspect of the present invention is a magnetic field generating means for generating a magnetic field having a plurality of magnetic poles, the magnetic poles generating a magnetic field having a magnetic field intensity regularly different in a predetermined displacement direction. Wherein the magnetic field generating means includes an N pole and an S pole arranged in the predetermined displacement direction.
A central magnetic pole row composed of one magnetic pole of the poles, and two magnetic poles arranged on both sides of the central magnetic pole row in a direction substantially orthogonal to the predetermined displacement direction, on both sides composed of the other magnetic poles of the N pole and the S pole, respectively. And a magnetic pole array. Therefore, in a magnetic pole arrangement having a three-pole structure including a central magnetic pole array and both magnetic pole arrays, a direction perpendicular to the predetermined displacement direction between the magnetic pole arrays on both sides and the central magnetic pole array (hereinafter also referred to as a magnetic pole width direction). ), A magnetization vector is generated, and in the predetermined displacement direction (hereinafter, also referred to as a magnetic pole length direction), the gap between the magnetic poles is almost non-magnetized. Therefore, the magnetic field strength between the magnetic pole and the magnetic pole in the magnetic pole length direction is reduced. The difference becomes clear, and the magnetic field intensity detection level at the magnetic pole tip is rectangularized.
In addition, since at least three magnetic poles having different polarities are arranged in parallel between magnetic poles adjacent in the magnetic pole width direction, the magnetic field is looped, and the magnetic field is hardly affected by another parallel magnetic pole row or a leakage magnetic field from the outside. Becomes

According to a second aspect of the present invention, there is provided a magnetic scale comprising a plurality of magnetic poles and a magnetic field generating means for generating a magnetic field having a magnetic field intensity that is regularly different in a predetermined displacement direction by the magnetic poles, wherein the magnetic field generating means is One of a central magnetic pole row composed of a plurality of magnetic poles arranged so that the polarities of the N pole and the S pole change alternately in the predetermined displacement direction, and one of the central magnetic pole row in a direction substantially orthogonal to the predetermined displacement direction. And a magnetic pole row on both sides including an N pole arranged on the side and an S pole arranged on the other side of the central magnetic pole row. Therefore, in the magnetic pole arrangement of the three-pole structure including the central magnetic pole row and the magnetic pole rows on both sides, the magnetic pole width direction from the N pole to the S pole in each part of the magnetic pole rows on both sides and the central magnetic pole row (with respect to the predetermined displacement direction) A magnetization vector in the (perpendicular direction) is generated, and the length of the region where the required magnetic field strength is obtained on the magnetic pole is sufficiently secured. Further, since the direction of the magnetic field changes periodically between the magnetic poles, a magnetic pattern having a predetermined pitch that does not cause a subpeak of the magnetic field intensity is formed even when the magnetic pole pitch is short. By appropriately setting the strength of the magnetic field of the magnetic pole row, the magnetic field distribution on each of the magnetic pole rows can be set in a suitable state.

The magnetic field generating means may include a magnet forming at least a central magnetic pole row of the central magnetic pole row and the magnetic pole rows on both sides, and the central magnetic pole row together with the magnet. And a magnetic material forming a predetermined magnetic path passing through the magnetic pole rows on both sides. Further, the central magnetic pole row may be formed along a predetermined straight line or circle as described in claim 4 or 5. A magnetic pole arrangement having a plurality of magnetic poles arranged in a vertical direction is possible. The magnetic pole row on the center side and the magnetic pole rows on both sides may be arranged in a plurality of rows so as to be arranged in parallel in a direction orthogonal to the predetermined displacement direction. The above magnetic pole arrangement can be realized by using a mechanically machined magnet or by directly magnetizing a magnetic material. The magnetic material is made of, for example, a high magnetic permeability material, and the characteristics can be improved by forming a magnetic path with a combination of the magnetic pole and the high magnetic permeability material.

According to a seventh aspect of the present invention, in order to achieve the above object, the magnetic scale according to any one of the first to sixth aspects, light emitting means for outputting an optical signal, and the central magnetic pole row are opposed to each other. A polarization rotating means provided at a predetermined position so as to rotate the polarization direction of the optical signal in accordance with the strength of the magnetic field formed by the central magnetic pole; a polarization control means for transmitting only polarized light in a specific polarization direction; A photoelectric conversion means for converting an optical signal transmitted through the control means into an electric signal; and an electric signal processing means for processing the electric signal from the photoelectric conversion means to obtain a specific physical quantity corresponding to the signal. The electric signal processing means, based on the electric signal from the photoelectric conversion means, the relative displacement between the magnetic scale and the polarization rotation means, as described in claim 8, , Speed and load Of time and requests at least one.

According to a ninth aspect of the present invention, there is provided a magnetic scale according to any one of the first to sixth aspects, wherein the magnetic scale is provided at a predetermined position so as to face the central magnetic pole row. A magnetic field strength detecting means including a magneto-electric conversion element which generates an electrical change in accordance with the strength of a magnetic field formed by the central magnetic pole; and an electric signal from the magnetic field strength detecting means being processed to specify a signal corresponding to the signal. Electrical signal processing means for determining a physical quantity of the magnetic scale and the magneto-electric conversion element, as described in claim 10, wherein the electrical signal processing means At least one of a typical displacement, velocity, and acceleration is determined.

[0013] The polarization rotating means may be, for example, an eleventh aspect.
As described in (1), the optical signal comprises a Voigt type magneto-optical effect element that senses a magnetic field component in a direction substantially orthogonal to the traveling direction of the light and changes the polarization direction of the light, or As described in 12, the Faraday arrangement type magneto-optical effect element, wherein the polarization rotation means senses a magnetic field component in a direction substantially parallel to the traveling direction of the light of the optical signal and changes the polarization direction of the light. It consists of

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. <First Embodiment> FIGS. 1 to 5 show the first to third embodiments.
12 is a diagram showing a magnetic scale and a magnetic detection device of a first embodiment according to the invention described in 12, and shows an example applied to a magnetic encoder as a linear position sensor.

First, the configuration will be described. 1A and 1B, reference numeral 10 denotes a magnetic scale, reference numeral 20 denotes a sensor head opposed to the magnetic scale 10, and the magnetic scale 10 is integrated with, for example, a displacement detection target (not shown) in FIG. By moving in the left and right directions in ()), the sensor head 20 can be displaced relative to the sensor head 20.

As shown in FIGS. 1A and 1B, a magnetic scale 10 includes a scale body 11 forming a magnetic pole surface 11a, and a plurality of magnetic pole rows arranged on the scale body 11 in parallel. The magnetic pole arrays 12 to 14 are formed, for example, by a plurality of magnet arrays 15, 16, 17 (magnetic field generating means) shown in FIG. The plurality of magnetic pole arrays 12 to 14 include a central magnetic pole array 12 located at the center in the width direction orthogonal to the relative displacement direction (predetermined displacement direction) between the magnetic scale 10 and the sensor head 20, and a central magnetic pole array 12 in the width direction. The central magnetic pole array 12 includes magnetic poles 12a having one of N and S poles at a predetermined pitch in the predetermined displacement direction. The central magnetic pole array 12 includes magnetic pole arrays 13 and 14 arranged on both sides of the magnetic pole array 12. It was done. The magnetic pole rows 13 and 14 on both sides are respectively magnetic poles 13a and 13a having the other polarity of the N pole and the S pole.
14a are arranged at the same pitch as the magnetic poles 12a in the predetermined displacement direction. The magnetic poles 12a of the central magnetic pole row 12 shown in FIG.
The 14 magnetic poles 13a and 14a are, for example, south poles, respectively, and these magnetic poles 12a to 14a are arranged in parallel at the same position in the relative displacement direction between the magnetic scale 10 and the sensor head 20.

As shown in FIG. 2 (a), the magnetic field generating means of this embodiment is configured such that one end portions (upper end portions in FIG. 2) of the block-shaped magnets 15, 16 and 17 are magnetic poles 12a, 13a and 13a.
These magnets are buried in the scale main body 11 made of the nonmagnetic material 11c. As shown in FIG. 2B, the other end surfaces of the block-shaped magnets 15 to 17 are in contact with a plate-shaped magnetic material 11 b made of a high magnetic permeability material provided in the scale main body 11. May be. Also, as shown in FIG.
It has a magnet 18 forming at least the central magnetic pole row 12 of the central magnetic pole row 12 and both magnetic pole rows 13 and 14, and rib portions 19a and 19b forming the remaining magnetic poles 13 and 14 on both sides of the magnet 18. U-shaped magnetic material 1
9, the same magnetic field generating means can be constituted. 2B and 2C, the magnet and the high-permeability magnetic material combined with the magnet pass through the central magnetic pole row 12 and the magnetic pole rows 13 and 14 on both sides. A predetermined loop-shaped magnetic path is formed, and the magnetic scale 10
Form a plurality of magnetic poles 12a to 14a having a predetermined magnetic pole length and a predetermined magnetic pole width on the scale main body 11, and form a magnetic pattern having a predetermined magnetic field intensity distribution spaced at predetermined intervals. Therefore, the magnetic scale 10 has a large magnetic field strength on the magnetic poles 12a to 14a in the predetermined displacement direction, and two adjacent magnetic poles 12a to 14a in the predetermined displacement direction (the direction of the bidirectional arrow in FIG. 1B). Magnetic fields having different magnetic field strengths are regularly generated between the two magnetic poles so as to reduce the magnetic field strength.

The sensor head 20 includes a head main body 21 and
An element 22 having an optical waveguide having a predetermined pattern formed thereon (hereinafter simply referred to as an optical waveguide); and a polarizer which is integrally mounted on the optical waveguide 22 so as to be interposed in a light traveling path and transmits polarized light in a specific direction from incident light. 23, a magneto-optical effect element 25 joined to the tip of the optical waveguide 22 on one surface side, and a reflection mirror section 26 formed on the other surface side of the magneto-optical effect element 25. Magneto-optical effect element 2
Reference numeral 5 is made of, for example, a soft magnetic material, has spontaneous magnetization in a direction substantially parallel to the traveling direction of light, and is internally magnetically saturated by the spontaneous magnetization. The magneto-optical effect element 25 is a polarization rotating means for rotating the plane of polarization of linearly polarized light passing therethrough in accordance with the strength of the magnetic field formed by the magnetic poles 12 to 14. For example, the magnetic field strength is equal to or less than a predetermined level. As a result, the polarization direction of the optical signal can be rotated by about 90 degrees by the spontaneous magnetization. The polarizer 23 is a laser diode.
An analyzer that transmits only polarized light in a specific direction out of the light from 91 to generate a linearly polarized optical signal and transmits only polarized light in a specific direction in the light path after transmitting through the magneto-optical effect element 25 (polarized light) Control means). Therefore, a magnetic field is applied to the magneto-optical effect element 25 by the magnetic poles 12 to 14 so as to orient the internal magnetization in a direction substantially orthogonal to the traveling direction of light (predetermined displacement direction), and the rotation angle of the plane of polarization of the linearly polarized light ( (Rotation of the polarization direction) can be minimized.

As shown in FIG. 3, the sensor head 20 has a predetermined shape (for example, a length of about 50 mm and a width of 5 to 2 mm).
A predetermined number of channels (for example, 2 to 16 channels) are integrally provided in parallel on a substrate having a size of about 0 mm.
That is, the sensor head 20 is a sensor head for one channel of a multi-channel head, and its optical waveguides 22 include, for example, a plurality of waveguides on the incident side (or branch into a plurality of paths on the way) and a plurality of waveguides on the emission side. Alternatively, a single waveguide is formed on the way. In the figure, 31 is a plurality of optical fibers connected to each channel of the sensor head 20, and 32 is a signal processing for outputting an optical signal to the sensor head 20 and converting the optical signal from the sensor head 20 into an electric signal. A circuit (electric signal processing means) 33 is an optical connector provided between the sensor head 20 and the signal processing circuit 32.

As shown in FIG. 4, the optical connector 33 includes a laser diode 42 (light emitting means) for outputting an optical signal in accordance with an input electric signal, and light after passing through each channel section 20c of the sensor head 20. A photodiode 43 (photoelectric conversion means) for converting a signal into an electric signal. The signal processing circuit 32 includes a laser diode 4
A light emission drive circuit 41 for driving light emission of the light emitting element 2, a comparator 44 for inputting an electric signal from the photodiode 43,
A counter 45 for counting the number of output pulses of the comparator 44 corresponding to the displacement amount;
And a subtractor 46 for inputting and storing the count value, and subtracting the previous count value from the count value to calculate a count value per predetermined time corresponding to the speed (predetermined physical quantity). . Further, although not shown in detail, the signal processing circuit 32 includes a CPU for controlling the light emission drive circuit 41 and a ROM in which a predetermined processing program is stored in advance.
And a RAM for exchanging data with the CPU and ROM
And the laser diode 42 and the photodiode 43
And an I / O circuit connected to the
The relative displacement, speed or acceleration between the magnetic scale 10 and the sensor head 20 is calculated based on the electric signal from the photodiode 43 in accordance with a predetermined control program stored in advance in M, or one side, for example, the sensor head The position of the magnetic scale 10 when 20 is fixed can be obtained. Of course, by converting a plurality of light intensity signals into a plurality of electric signals to generate a plurality of bits of signals including position information, it is possible to function as a so-called absolute type linear encoder. Further, the output of the subtractor 46 can be taken into another subtractor to calculate the speed change per predetermined time and detect the acceleration. That is, the signal processing circuit 32 is a means for determining any of the relative displacement, speed, and acceleration between the magnetic scale 10 and the sensor head 20 based on the electric signal from the photodiode 43.

When manufacturing the magnetic scale 10, first, magnets 15 to 17 are arranged in the non-magnetic material 11c of the scale main body 11 or on the magnetic material 11b (or a combination of the magnet 18 and the magnetic material 19). , Magnetic poles 12-1
4 is formed. Next, the nonmagnetic material 11 is placed in the gap between the magnets 15 to 17 (or between the magnet 18 and the magnetic material 19).
c is arranged and fixed around the magnets 15 to 17 to obtain the magnetic scale 10 having the illustrated shape. The magnet 1
5 to 17 materials are arranged and a non-magnetic material 11 is placed between them.
c may be arranged, and unnecessary portions may be removed by cutting or the like so as to form the magnetic poles 12 to 14 while leaving a region requiring a predetermined signal. In this case, a part of the non-magnetic material may be air in the removed space. In this embodiment, a permanent magnet is used for the magnetic field generating means, but it is needless to say that an electromagnet may be used.

Next, the operation will be described. In the apparatus of the present embodiment configured as described above, in the magnetic pole arrangement having a three-pole structure including the central magnetic pole array 12 and the magnetic pole arrays 13 and 14 on both sides, the magnetic pole arrays 13 and 14 on both sides and the central magnetic pole array 12, a magnetization vector is generated from the N pole to the S pole in the direction perpendicular to the plane of FIG. 1A and in the up-down direction (the magnetic pole width direction), and the left-right direction (magnetic pole) in FIG. Length and direction of displacement)
In, the state between the magnetic poles is substantially close to non-magnetization.

On the other hand, in the sensor head 20, light from the laser diode 42 enters the optical waveguide 22 and enters the polarizer 2.
3, a polarized light in a specific direction (linearly polarized light) is generated. When this light is incident on the magneto-optical effect element 25 which is spontaneously magnetized in a certain direction, the spontaneous magnetization causes rotation of the polarization direction (Faraday rotation). Occurs. When a magnetic field is applied to the magneto-optical effect element 25 by the magnetic scale 10 in a direction orthogonal to the direction of light propagation, the linearly polarized light advances without rotating the polarization direction. And
The light that has reached the output-side waveguide while being reflected by the reflection mirror unit 26 is transmitted through a polarizer 23 (polarization control unit) as an analyzer or shielded according to the polarization direction. That is, the sensor head 20 and the magnetic scale 1
When the intensity of the magnetic field acting on the magneto-optical effect element 25 falls below a predetermined level when the relative displacement of the magneto-optical effect element 25 is zero, the light is generated by the magnetic domain in the magneto-optical effect element 25 that is magnetically saturated by itself. While passing through 25, its polarization direction is rotated by about 90 degrees, and thereafter it cannot pass through the polarizer 23, so that the sensor head 20 does not output an optical signal. On the other hand, when a magnetic field in a direction orthogonal to the traveling direction of light is applied to the magneto-optical effect element 25 by the magnetic scale 10 due to the relative displacement between the sensor head 20 and the magnetic scale 10, the magnetic field is generated inside the magneto-optical effect element 25. Since the magnetic domain structure disappears and the linearly polarized light advances without rotating its polarization direction, the sensor head 20 outputs an optical signal (of course, the analyzer is arranged in a different direction to determine the presence or absence of the output). And vice versa).

In such a state, the magnetic scale 1
0 and each magnetic pole 1 in the relative displacement direction of the sensor head 20
Near the ends of the magnetic poles 2 to 14, a magnetic field strength distribution as shown by a thick line A in FIG. 5 is generated. On each of the magnetic poles 12 to 14, the magnetic field strength is sufficiently larger than the threshold level of the comparator 44, and At each position, the strength of the magnetic field becomes sufficiently smaller than the threshold level C of the comparator 44. The solid line B in the figure is a comparative example showing the magnetic field intensity distribution near the pole tip of the magnetic scale having the two-pole structure shown for comparison. This comparative example includes one magnetic pole row composed of a plurality of N poles arranged in a row in the direction of relative displacement with respect to the sensor head 20, and the other magnetic pole row composed of a plurality of S poles arranged in parallel with one magnetic pole row. It has a two-pole structure magnetic pole arrangement,
It is manufactured so that the magnetic field intensity at the detection height position near the center of the magnetic pole is the same level as in the above embodiment.

As shown in FIG. 5, in this embodiment, in the magnetic pole length direction, the magnetic field strength indicated by the bold line B is clearly different between the magnetic poles indicated by hatching in FIG. The detection level of the magnetic field strength in the section is made rectangular. Therefore, even if the threshold level C of the comparator 44 fluctuates as shown by the dotted line in FIG. 5, the detection position shifts as in the comparative example shown by the solid line B (shift in the displacement direction shown by the dotted line in FIG. 5). And accurate displacement, speed or acceleration can be detected. Furthermore, since at least three magnetic poles having different polarities are arranged in parallel between magnetic poles adjacent in the magnetic pole width direction, the magnetic field of the magnetic pole row of a plurality of channels is looped for each channel, and another magnetic pole row in parallel or external From being adversely affected by the leakage magnetic field.

In this embodiment, the sensor head 20 using a magneto-optical effect element has been described. In this sensor head 20, as shown in FIG. The above arrangement (hereinafter, referred to as Voigt arrangement) in which the direction is substantially orthogonal to the direction of the magnetization vector on the magnetic pole arrays 12 to 14 of the magnetic scale 10, or as shown in FIG. In any of the arrangements (hereinafter, referred to as Faraday arrangements) in which the traveling direction of the light and the directions of the magnetization vectors on the magnetic pole arrays 12 to 14 of the magnetic scale 10 are substantially parallel, any of the arrangements can be adopted.

In addition, a magneto-electric conversion element is provided in the sensor head 20 which does not use a magneto-optical element but opposes the magnetic pole arrays 12 to 14 and generates an electrical change in accordance with the magnetic field strength at a predetermined detection height. Means for detecting the intensity may be configured. In this case, the signal processing circuit 32 processes the electric signal from the magneto-electric conversion element and obtains a specific physical quantity according to the detected signal. For example, a sensor head (magnetic field intensity detecting element) including a Hall effect element or a magnetoresistive element as a magneto-electric conversion element, and a specific physical quantity is determined from a generated voltage or an electric resistance corresponding to the intensity of a magnetic field acting on the sensor head. , Velocity or acceleration can be obtained. <Second Embodiment> FIG. 7 shows a second embodiment according to the second aspect of the present invention.
It is a figure showing a magnetic scale of an example.

The present embodiment is completely the same as the first embodiment except for the arrangement of the magnetic poles. Therefore, the differences from the first embodiment will be mainly described, and the same as or equivalent to the first embodiment will be described. The same reference numerals as those in the first embodiment are used for the configuration.
7A, reference numeral 50 denotes a magnetic scale. The magnetic scale 50 includes a scale main body 51 and a magnetic scale 50 shown in FIG.
A central magnetic pole row 52 composed of a plurality of magnetic poles 52a and 52b arranged in a middle left-right direction (predetermined displacement direction), and a central magnetic pole row 52 in a magnetic pole width direction substantially orthogonal to the predetermined displacement direction.
The magnetic pole arrays 53 and 54 on both sides, each including an N pole arranged on one side and an S pole arranged on the other side of the central magnetic pole array 52
And The central pole row 52 comprises a north pole and a south pole.
The poles are composed of a plurality of magnetic poles 52a, 52b whose polarity alternates with N, S, N, S alternately in a predetermined displacement direction indicated by a bidirectional arrow in FIG. The magnetic poles 52a and 52b have sufficiently short magnetic pole lengths.

In this embodiment, in a magnetic pole arrangement having a three-pole structure consisting of a central magnetic pole row 52 and magnetic pole rows 53 and 54 on both sides, the magnetic pole rows 53 and 54 on both sides and each part of the central magnetic pole row 52 start from the N pole. A magnetization vector is generated in the magnetic pole width direction toward the S pole (a direction orthogonal to the predetermined displacement direction). Accordingly, the direction of the magnetic field periodically changes between the magnetic poles 52a and 52b, and the strength of the magnetic field in the predetermined displacement direction increases due to the magnetization vector from the N pole to the S pole between the magnetic poles 53 and 54 on both sides. become. As a result, even when the pitch between the magnetic poles 52a and 52b is small, a sub-peak of the magnetic field strength does not occur as in the related art, and the region length where the required magnetic field strength can be obtained on the magnetic poles 52a and 52b is sufficiently increased. Thus, a high-resolution magnetic scale can be obtained. Also, the magnetic pole rows 5 on both sides
By appropriately setting the magnetic field strengths of the magnetic pole arrays 5 and 3,
The magnetic field distribution above 2 to 54 can be brought to a state where a suitable detection level can be obtained. The sensor head 20 according to the present embodiment uses a magneto-electric conversion element or an element that causes Faraday rotation of an optical signal by a magnetic field in a predetermined detection direction on a magnetic scale 50 as a magneto-optical effect element 25. Any of these may be used. <Third Embodiment> FIG. 8 is a view showing a magnetic scale according to a third embodiment of the present invention.

In this embodiment, the magnetic pole arrays 12 to 1 of the first embodiment are used.
4 and the magnetic pole arrays 52 to 54 of the second embodiment having different magnetic pole pitches are arranged in parallel along predetermined straight lines L1 and L2. By employing a magnetic pattern in which a plurality of sets of magnetic pole rows having different pitches between magnetic poles are arranged in parallel in this manner, quick and highly accurate linear displacement detection can be performed based on sensor head outputs opposing each set of magnetic pole rows. . <Fourth Embodiment> FIG. 9 is a diagram showing a magnetic scale of a fourth embodiment according to the first and fifth aspects of the present invention, showing an example of application to a magnetic rotary encoder as a rotation angle sensor. .

In this embodiment, a plurality of magnetic poles 62 arranged at a predetermined pitch from one end face of a plurality of magnets similar to the first embodiment.
a, 63a, 64a, and by arranging the plurality of magnetic poles 62a, 63a, 64a along a circle L3 having a predetermined radius, a central magnetic pole row 62 and a circle L3 are formed.
Magnetic pole rows 63, 64 arranged on concentric circles inside and outside
And form. Here, the plurality of magnetic poles 62a, 63a, or 64a in the same circumferential magnetic pole row are arranged at predetermined angular intervals in the circumferential direction that is the predetermined detection direction, and the magnetic poles adjacent in the radial direction of the circle L3 are adjacent to each other. A plurality of magnetic poles 62a, 63a or 64 in the same magnetic pole row have opposite polarities.
“a” has a constant polarity arrangement. That is, the magnetic scale of the present embodiment is a disk-shaped one in which a plurality of magnets are embedded in the scale body so as to have the same polarity at predetermined angular intervals, and is substantially the same as the magnetic scale 10 of the first embodiment. It is made by the procedure. Although the example in which the magnetic pole surface is arranged on the disk is shown here, it goes without saying that the magnetic pole may be exposed on the side surface of the cylinder.

In this embodiment, the sensor head 20 is connected to a circle L3
The magnetic pole row 6
The rotation angle, angular velocity, or angular acceleration (specific physical quantity) of the encoder plate supporting 2 to 64 with respect to the sensor head can be detected with high accuracy. <Fifth Embodiment> FIG. 10 is a view showing a magnetic scale of a fifth embodiment according to the first, second, fourth and sixth aspects of the present invention.

As shown in the figure, in the magnetic scale of this embodiment, four magnetic patterns 7 corresponding to four channels are provided.
1, 72, 73, and 74 are linearly arranged with four sets of magnetic pole arrays 71a to 71d and 72 having different magnetic pole pitches.
a to 72d, 73a to 73c and 74a to 74c. Here, in the magnetic pole arrays 71a to 71d and 72a to 72d of the magnetic patterns 71 and 72, the magnetic poles 71b and 72b have the opposite polarities to the magnetic poles 71c and 72c, similarly to the magnetic pole arrays 52 to 54 of the second embodiment. . Magnetic pole arrays 73a to 73c and 74a to 74c of magnetic patterns 73 and 74
Are formed almost similarly to the magnetic pole arrays 12 to 14 of the first embodiment.

In this case, a sensor head for detecting the magnetic field intensity at the same position in the predetermined displacement direction for all the channels is provided, and the position can be detected with high accuracy from the detection information of all the channels. <Sixth Embodiment> FIG. 11 is a view showing a magnetic scale of a sixth embodiment according to the first, second, fifth and sixth aspects of the present invention.

As shown in the figure, in the magnetic scale of this embodiment, four magnetic patterns 8 corresponding to four channels are provided.
1, 82, 83, and 84 are arranged on four concentric circles and have four sets of magnetic pole arrays 81a to 81 having different magnetic pole pitches.
d, 82a-82d, 83a-83c and 84a-8
4c. Here, the magnetic pattern 8
The magnetic pole arrays 81a to 81d and 82a to 82d
Almost similarly to the magnetic pole arrays 71a to 71d and 72a to 72d of the fifth embodiment, the magnetic pole arrays 83a to 83d of the magnetic patterns 83 and 84 are provided.
83c, 84a to 84c are also the magnetic pole row 73a of the fifth embodiment.
73c and 74a to 74c.

In this case, a sensor head for detecting the magnetic field intensity at the same position in the angular displacement direction for all channels is provided, and highly accurate angular position detection and displacement direction detection can be performed from detection information of all channels. The sensor head 2 using the magneto-optical effect element in the above-described embodiment
Although 0 is a reflection type having a reflection surface, it goes without saying that it may be a transmission type.

[0037]

According to the first aspect of the present invention, the center magnetic pole row composed of one of the N pole and the S pole arranged in the predetermined displacement direction, and the center magnetic pole row in the direction substantially orthogonal to the predetermined displacement direction. A magnetic pole row on both sides composed of the other magnetic pole of the north pole and the south pole arranged on both sides of the central magnetic pole row,
Is provided, a magnetization vector is generated between the magnetic pole row on both sides and the central magnetic pole row in a direction orthogonal to the predetermined displacement direction, and the gap between the magnetic poles in the predetermined displacement direction is close to non-magnetized. As a result, the magnetic field strength detection level at the pole tip can be made rectangular by clarifying the difference in magnetic field strength between the magnetic pole and the magnetic pole in the predetermined displacement direction, providing a magnetic scale capable of highly accurate position detection. can do. Further, since at least three magnetic poles having different polarities are arranged in parallel between magnetic poles adjacent in the width direction orthogonal to the predetermined displacement direction, the magnetic field is looped to prevent adverse effects due to another parallel magnetic pole row or a leakage magnetic field from the outside. It can be hard to receive.

According to the second aspect of the present invention, the central magnetic pole row including a plurality of magnetic poles arranged so that the polarities of the N pole and the S pole alternately change in the predetermined displacement direction, N poles arranged on one side of the center pole row and S poles arranged on the other side of the center pole row in the direction orthogonal to each other.
And a magnetic pole row on both sides consisting of poles, so that a magnetic vector in a direction perpendicular to the predetermined displacement direction from the north pole to the south pole is generated at each part of the magnetic pole row on both sides and the central magnetic pole row. In addition, it is possible to sufficiently secure the length of the region where the required magnetic field strength is obtained on the magnetic pole, and it is possible to enhance the detection accuracy. Further, by periodically changing the direction of the magnetic field between the magnetic poles, it is possible to form a magnetic pattern having a predetermined pitch without causing a subpeak of the magnetic field intensity even when the magnetic pole pitch is short. By appropriately setting the magnetic field strength of the magnetic pole rows on both sides, the magnetic field distribution on each magnetic pole row can be optimized.

The magnetic field generating means may include a magnet forming at least a central magnetic pole row of the central magnetic pole row and the magnetic pole rows on both sides, and a central magnetic pole row together with the magnet. By using a magnetic material that forms a predetermined magnetic path passing through the magnetic pole rows on both sides, its magnetic characteristics can be improved, and a more accurate magnetic scale can be obtained. Further, as described in claims 4 and 5,
By arranging the central magnetic pole row along a predetermined straight line or circle, regardless of whether linear displacement or angular displacement is detected,
A highly accurate magnetic scale can be obtained only with a simple magnetic pole arrangement. Furthermore, multi-channel detection is possible by arranging a plurality of central pole rows and magnetic pole rows on both sides in parallel in a direction orthogonal to the predetermined displacement direction as described in claim 6. A magnetic scale having a larger length measurement range can be obtained.

According to the seventh aspect of the present invention, a polarization rotating means is provided on the side of the magnetic scale on which the magnetic pole is exposed, and the polarization direction of the optical signal sent to the polarization rotating means is changed by a magnetic field in a predetermined direction formed by the magnetic pole. Rotate according to the strength of the
The polarization control means is interposed in the path of the optical signal to generate a light intensity signal corresponding to the magnetic field intensity, which is converted into an electric signal for signal processing, so that high-precision position detection can be performed even in harsh environments. Thus, it is possible to provide a magneto-optical modulation type magnetic detection device having an excellent resolution.

According to the ninth aspect of the present invention, the magnetic scale is provided at a predetermined position so as to face the central magnetic pole row, and is electrically connected in accordance with the strength of the magnetic field formed by the central magnetic pole. A magnetic field strength detecting means including a magneto-electric conversion element causing a change, and an electric signal processing means for processing an electric signal from the magnetic field strength detecting means to obtain a specific physical quantity according to the signal, A magnetic detection device having a simple configuration can be obtained. In particular, by arranging N-pole and S-pole magnetic poles that are close to each other in the predetermined detection direction and are exposed on the same surface side in a predetermined displacement direction, so that downward magnetization is not generated between magnetic poles adjacent in the direction. It is possible to easily use a magnetic field strength detecting element composed of a magneto-electric transducer such as a magnetoresistive effect element or a Hall effect element, and it is also possible to reduce the distance between the magnetic scale and the magnetic field strength detecting element. As a result, the resolution and S / N ratio of the detection device can be improved. According to a tenth aspect of the present invention, the electric signal processing means determines at least one of a relative displacement, a velocity, and an acceleration between the magnetic scale and the magneto-electric transducer. Claims 8 and 10
As described in above, at least one of the relative displacement (including the position with respect to the fixed side), the velocity, and the acceleration between the magnetic scale and the polarization rotating means can be obtained with high accuracy.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a first embodiment of the present invention;
(A) is a plan view showing the magnetic pole arrangement of the magnetic scale,
(B) is a plan view including the sensor head.

FIG. 2 is a cross-sectional view showing two modes of the magnetic field generating means.

FIG. 3 is a perspective view showing the overall configuration of the magnetic position detecting device of the first embodiment.

FIG. 4 is a block diagram illustrating a configuration of a signal processing circuit illustrated in FIG. 3;

FIG. 5 is a diagram showing a magnetic field intensity distribution near a magnetic pole tip in the first embodiment.

FIG. 6 is a view showing two aspects of the sensor head of the first embodiment.

FIG. 7 is a diagram showing a schematic configuration of a second embodiment of the present invention;
(A) is a plan view showing the magnetic pole arrangement of the magnetic scale,
(B) is a plan view including the sensor head.

FIG. 8 is a view showing a magnetic pole arrangement of a magnetic scale according to a third embodiment of the present invention.

FIG. 9 is a view showing a magnetic pole arrangement of a magnetic scale according to a fourth embodiment of the present invention.

FIG. 10 is an arrangement view of a plurality of rows of magnetic poles of the magnetic scale showing a fifth embodiment of the present invention.

FIG. 11 is a layout view of a plurality of rows of magnetic poles of the magnetic scale showing a sixth practical example according to the present invention.

[Explanation of symbols]

10; 50 Magnetic scale 11; 51 Scale main body 11a; 51a Scale surface (magnetic pole exposed surface) 11b, 19 Magnetic material 12; 52; 62; 71b, 71c, 72b, 72c,
73b, 74b; 81b, 81c, 82b, 82c, 8
3b, 84b Central magnetic poles 12a, 13a, 14a; 52a, 52b Magnetic poles 13, 14, 53, 54; 63, 64; 71a, 71
d, 72a 72d, 73a, 73c, 74a, 74c;
81a, 81d, 82a, 82d, 83a, 83c, 84
a, 84c Magnetic pole arrays on both sides 15-17, 18 Magnet (magnetic field generating means) 20 Sensor head (magnetic field detecting means) 22 Optical waveguide (optical waveguide forming element) 23 Polarizer (polarization controlling means) 25 Magneto-optical effect element (polarized light) Rotating means) 32 signal processing circuit (electric signal processing means) 42 laser diode (light emitting means) 43 photodiode (photoelectric conversion means)

Claims (12)

[Claims] 1. A magnetic scale comprising a plurality of magnetic poles and a magnetic field generating means for generating a magnetic field having a magnetic field intensity that is regularly different in a predetermined displacement direction by the magnetic poles, wherein the magnetic field generating means is arranged in the predetermined displacement direction. A central magnetic pole row composed of one of the arranged N and S poles,
A magnetic scale, comprising: a magnetic pole row on both sides formed of the other magnetic pole of the N pole and the S pole arranged on both sides of the central magnetic pole row in a direction substantially orthogonal to the predetermined displacement direction. 2. A magnetic scale comprising: a plurality of magnetic poles; and a magnetic field generating means for generating a magnetic field having a magnetic field intensity that is regularly different in a predetermined displacement direction by the magnetic poles. A central magnetic pole row composed of a plurality of magnetic poles arranged so that the polarities of the N pole and the S pole alternately change, and N magnetic poles arranged on one side of the central magnetic pole row in a direction substantially orthogonal to the predetermined displacement direction. And a magnetic pole row on both sides comprising an S pole arranged on the other side of the central magnetic pole row. 3. The magnetic field generating means includes: a magnet forming at least a central magnetic pole row of the central magnetic pole row and the magnetic pole rows on both sides; and a central magnetic pole row and the magnetic pole rows on both sides together with the magnet. The magnetic scale according to claim 1, further comprising: a magnetic material that forms a predetermined magnetic path that passes therethrough. 4. The magnetic scale according to claim 1, wherein said central magnetic pole row has a plurality of magnetic poles arranged along a predetermined straight line. 5. The magnetic scale according to claim 1, wherein the central magnetic pole row has a plurality of magnetic poles arranged along a circle having a predetermined radius. 6. The magnetic pole row on the center side and the magnetic pole rows on both sides are arranged in a plurality of rows so as to be parallel to each other in a direction orthogonal to the predetermined displacement direction.
5. The magnetic scale according to any one of 5. 7. A magnetic scale according to claim 1; a light emitting means for outputting an optical signal; and a light emitting means provided at a predetermined position so as to face the central magnetic pole row.
Polarization rotating means for rotating the polarization direction of the optical signal according to the strength of the magnetic field formed by the central magnetic pole, polarization control means for transmitting only polarized light in a specific polarization direction, and an optical signal after passing through the polarization control means Magnetic detection, comprising: photoelectric conversion means for converting the electric signal into an electric signal; and electric signal processing means for processing the electric signal from the photoelectric conversion means to obtain a specific physical quantity according to the signal. apparatus. 8. The electric signal processing means for determining at least one of relative displacement, velocity and acceleration between the magnetic scale and the polarization rotating means based on an electric signal from the photoelectric conversion means. The magnetic detection device according to claim 7, wherein: 9. A magnetic scale according to claim 1, wherein said magnetic scale is provided at a predetermined position so as to face said central magnetic pole row,
A magnetic field intensity detecting means including a magneto-electric conversion element that generates an electric change according to the intensity of a magnetic field formed by the central magnetic pole; and an electric signal from the magnetic field intensity detecting means is processed to specify the signal in accordance with the signal. And an electric signal processing means for obtaining a physical quantity of the magnetic field. 10. The magnetic system according to claim 9, wherein said electric signal processing means obtains at least one of a relative displacement, a velocity, and an acceleration between said magnetic scale and said magneto-electric transducer. Detection device. 11. The apparatus according to claim 11, wherein said polarization rotating means comprises a magneto-optical effect element for sensing a magnetic field component in a direction substantially orthogonal to the traveling direction of the light of the optical signal and changing the polarization direction of the light. A magnetic detection device according to claim 7. 12. The apparatus according to claim 1, wherein said polarization rotating means comprises a magneto-optical effect element for sensing a magnetic field component in a direction substantially parallel to the traveling direction of the light of the optical signal and changing the polarization direction of the light. A magnetic detection device according to claim 7.