JP2011214850A - Position detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position detector which enlarges a distance between a magnetic sensor and a magnetic scale surface.SOLUTION: The position detector 1 is equipped with: the magnetic scale 3 which has a surface 3a extending along the direction (x direction) of movement of an object being a position detection target and is magnetized so that the N-pole and the S-pole appear alternately along the x direction in the surface 3a; a plurality of magnetic bodies 5 which are disposed on the surface 3a for the individual poles that appear on the surface 3a; and the magnetic sensor 2 which is constituted to be movable together with the object and disposed opposite to the surface 3a. The magnetic bodies 5 are disposed at the central parts in the x direction of the corresponding magnetic poles respectively.

Description

  The present invention relates to a position detection device, and more particularly to a position detection device using a magnetic scale and a magnetic sensor.

  Some industrial equipment such as a mounter includes a position detection device that detects the position of an object using magnetism in order to detect the position of a moving object (see, for example, Patent Document 1).

  FIG. 12 is a diagram showing a position detection device 10 according to the background art of the present invention. As shown in the figure, the position detection device 10 has a magnetic sensor 20 attached to a position detection target object (not shown), and a surface 30a extending in the moving direction of the object (shown in the x direction) The surface 30a is provided with a magnetic scale 30 magnetized so that N poles and S poles appear alternately.

  A curve with an arrow shown in FIG. 12 represents a magnetic field line of a magnetic field created by the magnetic scale 30. As shown in the figure, this magnetic field forms a magnetic reversal region I in the vicinity of the center of each magnetic pole formed on the surface 30 a of the magnetic scale 30. The position detection device 10 has a function of detecting the magnetic reversal region I using the magnetic sensor 20, and counts the number of magnetic reversal regions I detected along with the movement of the object. The position (movement distance) of is detected. Alternatively, the position (movement position) of the object may be detected from the output value of the magnetic sensor 2 based on the data table. Here, in the data table, the output value of the magnetic sensor 2 and the movement distance of the position detection target (not shown) may correspond discretely according to the movement distance of the magnetic sensor 2.

JP-A-61-82112

  However, in the position detection device 10, it is necessary to bring the magnetic sensor 20 and the surface 30 a of the magnetic scale 30 very close to each other in order to perform accurate position detection. Therefore, high-precision assembly is required, and the manufacturing cost is increased.

  Accordingly, one of the objects of the present invention is to provide a position detecting device capable of enlarging the distance between the magnetic sensor and the magnetic scale surface.

  In order to achieve the above object, a position detection apparatus according to the present invention has a surface extending along a moving direction of an object to be position-detected, and N poles and S poles alternate on the surface along the moving direction. A plurality of magnetic scales magnetized so as to appear on the surface, a plurality of magnetic bodies disposed on the surface, and a magnetic sensor configured to be movable together with the object and disposed to face the surface. The magnetic body is provided for each magnetic pole appearing on the surface, and is disposed in the center of the corresponding magnetic pole in the moving direction.

  According to the present invention, since the magnetic inversion region is emphasized, the distance between the magnetic sensor and the magnetic scale surface can be increased. In the present invention, “movement” means relative movement of the position detection target object and the magnetic scale. That is, for example, when the ground surface is considered as a reference, the magnetic scale may be fixed with respect to the ground surface, and the object may move with respect to the ground surface. It may be moved with respect to the ground surface, or both the object and the magnetic scale may be moved in different directions with respect to the ground surface.

  In the position detection device, it is preferable that the length of each magnetic body in the moving direction is not less than 26% and not more than 60% of the length of the corresponding magnetic pole in the moving direction. The length of the surface of each magnetic body in the normal direction is preferably 15% or less of the width of the magnetic body. The length of the surface of the magnetic scale in the normal direction is preferably 30% or more and 100% or less of the width of each magnetic pole.

  Further, in the position detection device, each of the magnetic bodies may be a magnetic film formed on the surface by thick film printing, and each of the magnetic bodies may be a magnetic body attached to the surface. It may be an individual piece.

  According to the present invention, since the magnetic inversion region is emphasized, the distance between the magnetic sensor and the magnetic scale surface can be increased.

It is a figure which shows the structure of the position detection apparatus 1 by embodiment of this invention. (A) and (b) show the result of simulating the magnetic field of the cross section corresponding to the region A shown in FIG. 1 for the position detection device according to the background art of the present invention and the position detection device according to the present embodiment. FIG. It is the figure which showed (DELTA) B about each of the position detection apparatus by the background art of this invention, and the position detection apparatus by this Embodiment on the bar graph. _{5mm d 1, d 2, d} 5 respectively, shows 2 mm, the variation of the difference ΔB when the _{d 4} fixed to 0.1mm changed in 1mm units from 0mm to 5 mm. FIG. 5 is a diagram illustrating a result of simulating a magnetic field of a cross section corresponding to a region A illustrated in FIG. 1 for each value of d ₄ illustrated in FIG. 4. _{5mm d 1, d 2, d} 4 , respectively, a diagram showing 2mm, the change in the difference ΔB when the _{d 5} is fixed to 2mm changed in four steps from 0.1mm to 2mm. FIG. 7 is a diagram illustrating a result of simulating a magnetic field of a cross section corresponding to a region A illustrated in FIG. 1 for each value of d ₅ illustrated in FIG. 6. _{d 1,} d 4, d _5, respectively 5 mm, illustrates 2 mm, the variation of the difference ΔB of changing in four steps fixed to 0.1mm and _{d 2} from 1mm to 5 mm. FIG. 9 is a diagram illustrating a result of simulating a magnetic field of a cross section corresponding to a region A illustrated in FIG. 1 for each value of d ₂ illustrated in FIG. 8. _{d 1, d 2, d 4} , d 5 respectively 5mm, 2mm, 2mm, fixed to 0.1 mm, which is a graph showing changes in difference ΔB of changing the material of the magnetic scale and the magnetic. It is a figure which shows the result of having simulated the magnetic field of the cross section corresponding to the area | region A shown in FIG. 1 for every combination of the material of a magnetic scale and a magnetic body. It is a figure which shows the position detection apparatus by the background art of this invention.

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

  FIG. 1 is a diagram showing a configuration of a position detection apparatus 1 according to an embodiment of the present invention. As shown in the figure, a position detection device 1 includes a magnetic sensor 2 attached to an object (not shown) as a position detection target, and a magnetic scale having surfaces 3a and 3b extending in the x direction (moving direction of the object). 3, a yoke portion 4 provided along the surface 3 b, and a plurality of magnetic bodies 5 disposed on the surface 3 a.

The magnetic scale 3 is a ferromagnetic material magnetized so that N poles and S poles appear alternately along the x direction on the surface 3a. The width of each magnetic pole (length in the x-direction) is d _1, (the normal direction of the length of the surface 3a) the height of the magnetic scale 3 is d _2. Specifically, the magnetic scale 3 is constituted by a plurality of permanent magnets juxtaposed. As shown in FIG. 1, each permanent magnet is preferably arranged so that one magnetic pole surface (S pole or N pole) is exposed on the surface 3a. Each permanent magnet is preferably a ferrite magnet or a bonded magnet.

  The curve with arrows shown in FIG. 1 represents the magnetic field lines of the magnetic field created by the magnetic scale 3. As shown in the figure, this magnetic field forms a magnetic reversal region I near the center of each magnetic pole formed on the surface 3 a of the magnetic scale 3.

The magnetic sensor 2 is configured to be movable together with the position detection target object, and is disposed to face the surface 3a. The magnetic sensor 2 is installed in a position away from the surface 3a by a distance d _3. The magnetic sensor 2 includes a magnetoresistive element such as a GMR (giant magnetoresistive) element or an AMR (Anisotropic magnetoresistive) element. The position detection device 1 has a function of detecting the magnetic reversal region I using the magnetic sensor 2, and by counting the number of magnetic reversal regions I detected as the object moves, The position (movement distance) is detected. Alternatively, the position (movement position) of the object may be detected from the output value of the magnetic sensor 2 based on the data table. Here, in the data table, the output value of the magnetic sensor 2 and the movement distance of the position detection target (not shown) may correspond discretely according to the movement distance of the magnetic sensor 2.

  The yoke portion 4 is a member that functions as a magnetic path of a magnetic field created by the magnetic scale 3 and is made of a magnetic material.

The magnetic body 5 is disposed for each magnetic pole appearing on the surface 3a of the magnetic scale 3, and as shown in FIG. The width of the individual magnet body 5 (the length of the x direction) with d _4, the height (length in the direction normal to the surface 3a) is d _5. As a specific material of the magnetic body 5, it is preferable to use stainless steel (SUS440 or the like) or steel.

The magnetic body 5 may be manufactured by forming a magnetic film made of a magnetic material such as stainless steel or steel on the surface 3a by thick film printing, or a magnetic individual piece (width) such as stainless steel or steel. d _4, the magnetic body pieces) of height d ₅ may also be produced by pasting on the surface 3a. Further, it may be formed on the surface of the permanent magnet before the magnetic scale 3 is assembled, or may be formed on the surface 3 a after the magnetic scale 3 is assembled.

  By arranging the magnetic body 5, the magnetic reversal region I is emphasized in the position detection device 1 compared to the position detection device 10 (FIG. 12) according to the background art. Hereinafter, this point will be described in detail while showing simulation results.

2 (a) and 2 (b) show results of simulating the magnetic field of the cross section corresponding to the region A shown in FIG. 1 for the position detection device 10 according to the background art and the position detection device 1 according to the present embodiment, respectively. FIG. In this simulation, d ₁ = 5 mm, d ₂ = 2 mm, d ₄ = 2 mm, d ₅ = 0.1 mm, and the same applies to the position detection device 10. Moreover, the material of the magnetic scale 3 and the magnetic body 5 was made into the ferrite magnet and SUS440, respectively.

  As can be understood by comparing FIGS. 2A and 2B, in the position detection device 1, the magnetic body 5 is absorbed by the magnetic body 5 by arranging the magnetic body 5. The magnetic field is small. On the other hand, there is not much difference between the ends of the magnetic poles.

  The degree of emphasis of the magnetic reversal region I can be expressed by the difference ΔB = B2−B1 between the magnetic field B1 above the central portion in the x direction of the magnetic pole and the magnetic field B2 above the end of the magnetic pole. Here, if magnetic fields B1 and B2 at positions P1 and P2 at 1 mm from the surface 3a (1 mm from the upper surface of the magnetic body 5 when there is the magnetic body 5) are used, as shown in FIG. In the position detection device 10, B1 and B2 are 0.2T and 0.24T, respectively. Therefore, ΔB = 0.04T. On the other hand, in the position detection apparatus 1, B1 and B2 are 0.15T and 0.23T, respectively. Therefore, ΔB is 0.08T.

FIG. 3 is a bar graph showing ΔB of each of the position detection devices 1 and 10. As is clear from the figure, in the position detection device 1, the magnetic inversion region I is emphasized compared to the position detection device 10. Therefore, the distance d ₃ between the magnetic sensor and the surface 3 a can be increased as compared with the position detection device 10.

Hereinafter, the optimum values of d ₂ , d ₄ , and d ₅ and the optimum materials for the magnetic scale 3 and the magnetic body 5 will be specifically described with reference to simulation results. In the following simulation results, the meanings of B1, B2, and ΔB are the same as described above.

First, FIG. 4 is a diagram showing a change in the difference ΔB when d ₁ , d ₂ , and d ₅ are fixed to 5 mm, 2 mm, and 0.1 mm, respectively, and d ₄ is changed from 0 mm to 5 mm in 1 mm units. . The material of the magnetic scale 3 and the magnetic body 5 was a ferrite magnet and SUS440, respectively. 5, the values of each of the d _4, a diagram illustrating a result of simulating the magnetic field of the cross section corresponding to the region A shown in FIG. FIGS. 2A and 2C are reprints of FIGS. 2A and 2B, respectively. In FIG. 5, the drawing of the magnetic scale 3 and the magnetic body 5 is omitted, and this is the same in each of the following drawings. Table 1 below summarizes the values of B1, B2, and ΔB obtained as a result of the simulation.

Next, FIG. 6 is a diagram showing changes in the difference ΔB when d ₁ , d ₂ , and d ₄ are fixed to 5 mm, 2 mm, and 2 mm, respectively, and d ₅ is changed in four steps from 0.1 mm to 2 mm. is there. The material of the magnetic scale 3 and the magnetic body 5 was a ferrite magnet and SUS440, respectively. 7, the value of each d _5, is a graph showing the results of simulation of the magnetic field of the cross section corresponding to the region A shown in FIG. FIG. 2A is a reproduction of FIG. 2B. Table 2 below summarizes the values of B1, B2, and ΔB obtained as a result of the simulation.

Next, FIG. 8 is a diagram illustrating a change in the difference ΔB when d ₁ , d ₄ , and d ₅ are fixed to 5 mm, 2 mm, and 0.1 mm, respectively, and d ₂ is changed in four steps from 1 mm to 5 mm. is there. The material of the magnetic scale 3 and the magnetic body 5 was a ferrite magnet and SUS440, respectively. 9, for each of the d ₂ values is a diagram showing the results of simulation of the magnetic field of the cross section corresponding to the region A shown in FIG. FIG. 2B is a reproduction of FIG. 2B. Table 3 below summarizes the values of B1, B2, and ΔB obtained as a result of the simulation.

Next, FIG. 10 shows the difference ΔB when d ₁ , d ₂ , d ₄ , and d ₅ are fixed to 5 mm, 2 mm, 2 mm, and 0.1 mm, respectively, and the materials of the magnetic scale 3 and the magnetic body 5 are changed. It is a figure which shows a change. FIG. 11 is a diagram showing the result of simulating the magnetic field of the cross section corresponding to the region A shown in FIG. 1 for each combination of materials of the magnetic scale 3 and the magnetic body 5. FIG. 2A is a reproduction of FIG. 2B. Table 4 below summarizes the values of B1, B2, and ΔB obtained as a result of the simulation. In this simulation, ΔB was simulated for the three combinations shown in Table 4 below.

Referring to FIG. 4, ΔB has a maximum value of 0.08T when the width d _{4 in} the x direction of each magnetic body 5 is 2 mm, and ΔB is 1 of ΔB = 0.04T of the position detection device 10. .5 times or more (0.06 T) is when the width d ₄ is approximately 1.3 mm or more and 3 mm or less.

Referring to FIG. 6, ΔB has a maximum value of 0.08T when the height d ₅ of each magnetic body ₅ is 0.1 mm, and ΔB is ΔB = 0.04T of the position detection device 10. Is 1.5 times or more (0.06 T) when the height d ₅ is approximately 0.3 mm or less.

Referring to FIG. 8, ΔB has a maximum value of 0.08T when the height d ₂ of the magnetic scale 3 is 2 mm, and ΔB is 1.B where ΔB = 0.04T of the position detection device 10. 5 times or more (0.06T) as made is when the height _{d 2} is approximately 1.5mm or 5mm or less.

From the above results, the values of d ₂ , d ₄ , and d ₅ are optimally 2 mm, 2 mm, and 0.1 mm, respectively, and 1.5 ≦ d ₂ ≦ 5, 1.3 ≦ d ₄ ≦ 3, d _It can be said that the magnetic reversal region I can be sufficiently emphasized when ₅ ≦ 0.3 is satisfied. In terms of the relation between the width d _{4 in} the x direction of each magnetic body 5 and the width d ₁ (= 5 mm) of the magnetic pole appearing on the surface 3 a, it can be said that it is preferably 26% or more and 60% or less of the width d ₁ . Further, in terms of the relationship between the height of the magnetic material 5 (in the normal direction length) width d ₄ of the magnetic body 5 for d5 ₍₌ 2 mm), it can be said that it is preferably not more than 15% of the width d ₄ . In addition, regarding the height (length in the normal direction) d ₂ of the magnetic scale 3 in relation to the magnetic pole width d ₁ (= 5 mm), the height is set to be between 30% and 100% of the width d _1. It can be said that it is preferable.

  Moreover, it can be said from the result of FIG. 10 that the materials of the magnetic scale 3 and the magnetic body 5 simulated this time can be suitably used.

  As described above, according to the position detection device 1 according to the present embodiment, the magnetic reversal region I is emphasized. Therefore, since the distance between the magnetic sensor and the magnetic scale surface can be increased, it is not necessary to assemble with high accuracy, and the manufacturing cost of the position detecting device can be reduced as compared with the conventional case.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to such embodiment at all, and this invention can be implemented in various aspects in the range which does not deviate from the summary. Of course.

DESCRIPTION OF SYMBOLS 1 Position detection apparatus 2 Magnetic sensor 3 Magnetic scale 3a, 3b Surface of magnetic scale 4 Yoke part 5 Magnetic body

Claims (6)

A magnetic scale having a surface extending along a moving direction of an object to be position-detected, and magnetized so that N poles and S poles appear alternately along the moving direction on the surface;
A plurality of magnetic bodies disposed on the surface;
A magnetic sensor configured to be movable with the object and disposed opposite the surface;
The plurality of magnetic bodies are provided for each magnetic pole appearing on the surface, and each magnetic body is disposed at a central portion of the corresponding magnetic pole in the moving direction. The position detection device according to claim 1, wherein a length of each magnetic body in the movement direction is 26% or more and 60% or less of a length of the corresponding magnetic pole in the movement direction. The position detection device according to claim 1 or 2, wherein the length of the surface of each magnetic body in the normal direction is 15% or less of the length of the magnetic body in the movement direction. 4. The length of the surface of the magnetic scale in the normal direction is 30% or more and 100% or less of the length of the magnetic poles in the movement direction. 5. The position detection device described. 5. The position detection device according to claim 1, wherein each of the magnetic bodies is a magnetic film formed on the surface by thick film printing. The position detection device according to any one of claims 1 to 4, wherein each of the magnetic bodies is a magnetic piece attached to the surface.

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