TWI844277B - Magnetic scale, mover and drive device - Google Patents

Abstract

Provide a positioning scale that can effectively detect, etc.

A magnetic scale (C1, C2) is mounted on a mover and magnetic positioning is performed by a magnetic sensor (S1-S5) arranged on a track of the mover. A shielding member (B1R, B2L) for magnetically shielding the magnetic sensor (S1-S5) is provided on at least one end (E1R, E2L) of the magnetic scale (C1, C2). The length of the shielding member (B1R, B2L) in the track direction is more than half of the length obtained by subtracting the minimum approachable distance of a plurality of movers from the length of the detection range (R) of the magnetic sensor (S1-S5) in the track direction. The shielding member (B1R, B2L) is formed by a ferromagnetic material that magnetically shields at least one end (E1R, E2L) of the magnetic scale (C1, C2) from the magnetic sensor (S1-S5).

Description

Magnetic scale, mover and drive device

The present invention relates to a driving device for moving a mover along a track, etc.

Patent document 1 discloses a linear transport system as a driving device for moving a mover along a track. A plurality of magnetic sensors arranged along the track position a magnetic scale (i.e., the mover) mounted on the mover.

[Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 2021-164396

When there are multiple movers in the linear transport system of Patent Document 1, two movers (i.e., magnetic scales) that are close to each other may enter the detection range of a magnetic sensor at the same time. In this case, the magnetic sensor cannot distinguish the two magnetic scales for detection.

This invention was completed in view of these conditions, and its purpose is to provide a positioning scale that can effectively detect, etc.

In order to solve the above-mentioned problem, one aspect of the positioning scale of the present invention is mounted on the mover, and is positioned by a position detection part arranged on the track of the mover, and is provided with a shielding member that shields at least one end from the position detection part.

According to this aspect, even if the ends of the positioning scales of two movers close to each other enter the detection range of the position detection unit at the same time, the shielding member provided on at least one of the ends can prevent the positioning scales from being misdetected.

Another aspect of the present invention is a mover. The mover is equipped with a positioning scale, which is positioned by a position detection part arranged on the track of the mover, and has a shielding member that shields at least one end from the position detection part.

Another aspect of the present invention is a driving device. The device comprises: a plurality of movers, which are driven along a track; a position detection unit, which is arranged on the track and detects the positions of the plurality of movers; and a plurality of positioning scales, which are mounted on the plurality of movers and positioned by the position detection unit, and have a shielding member that shields at least one end from the position detection unit.

In addition, any combination of the above constituent elements or the conversion of such expressions into methods, devices, systems, recording media, computer programs, etc. are also included in the present invention.

According to the present invention, the positioning scale can be effectively detected.

1: Linear handling system

2: Stator

3, 3A, 3B, 3C, 3D: mover

4: Positioning device

40: Reference mark detection control department

41: Benchmark Marker Detection Validation Department

42: Benchmark mark detection invalidation department

51, 52, 53, 54, 55: Counting Department

AB1: Scale body

B1R, B2L: shielding components

C1, C2: Magnetic scale (motor)

S1: Magnetic sensor

Z1, Z2: Reference mark

ElR, E1L: End

[Figure 1] is a three-dimensional diagram showing the overall structure of the linear handling system.

[Figure 2] schematically shows a positioning device composed of a position detection unit and a positioning scale in a linear transport system.

[Figure 3] schematically shows the situation where the positioning body of the moving magnetic scale switches from the magnetic sensor at the moving source to the magnetic sensor at the moving destination.

[Figure 4] shows an embodiment in which the benchmark mark detection validation unit and/or the benchmark mark detection invalidation unit are not used.

[Figure 5] shows an embodiment in which the benchmark mark detection validation unit and/or the benchmark mark detection invalidation unit are not used.

[Figure 6] shows an embodiment of using a benchmark mark detection validation unit and/or a benchmark mark detection invalidation unit.

[Figure 7] shows an embodiment of using a benchmark mark detection validation unit and/or a benchmark mark detection invalidation unit.

[Figure 8] schematically shows the state where two magnetic scales approaching the minimum accessible distance simultaneously enter the detection range of a magnetic sensor.

[Figure 9] shows the first embodiment in which a plurality of movers move at a constant speed.

[Figure 10] shows the first embodiment in which a plurality of movers move at a constant speed.

[Figure 11] shows the second embodiment in which a plurality of movers move at a constant speed.

[Figure 12] shows the second embodiment in which a plurality of movers move at a constant speed.

[Figure 13] shows the third embodiment in which a plurality of movers move at a constant speed.

[Figure 14] shows the third embodiment in which a plurality of movers move at a constant speed.

Below, the embodiments for implementing the present invention (hereinafter also referred to as implementation methods) are described in detail with reference to the drawings. In the description and/or drawings, the same or equivalent components, components, processes, etc. are marked with the same symbols and repeated descriptions are omitted. The scale and shape of each part shown in the figure are conveniently set for the purpose of simplifying the description, and no limiting interpretation is made unless otherwise specifically mentioned. The implementation methods are illustrative and do not limit the scope of the present invention in any way. All the features and combinations of the features recorded in the implementation methods are not necessarily limited to the essence of the present invention.

FIG1 is a perspective view showing the overall structure of a linear transport system 1 as one embodiment of the drive device of the present invention. The linear transport system 1 includes a stator 2 that forms an annular rail or track, and a plurality of movers 3A, 3B, 3C, and 3D (hereinafter collectively referred to as movers 3) that are driven relative to the stator 2 and can move along the rail. The electromagnetic or coil disposed on the stator 2 and the permanent magnet disposed on the mover 3 are opposed to each other, so that a wired motor is formed along the annular rail. In addition, the rail formed by the stator 2 can be any shape, not limited to an annular shape. For example, the guide rail can be straight or curved, one guide rail can be branched into multiple guide rails, and multiple guide rails can be merged into one guide rail. In addition, the setting direction of the guide rail formed by the stator 2 is also arbitrary. In the example of Figure 1, the guide rail is arranged in a horizontal plane, but the guide rail can also be arranged in a vertical plane, or in a plane or curved surface with any inclination angle.

The stator 2 has a rail surface 21 with the horizontal direction as the normal direction. The rail surface 21 extends in a band shape along the direction in which the rail is formed, and forms a ring-shaped band shape by connecting (imaginary) two ends when a ring-shaped rail is formed as in the example of FIG. 1 . On the rail surface 21 that can form a rail of any shape as described above, a plurality of drive modules (not shown) having electromagnets are continuously or periodically buried or arranged along the rail. The electromagnets in the drive modules generate a magnetic field that applies a thrust along the rail to the permanent magnets of the mover 3 and/or the electromagnets themselves. Specifically, if a driving current such as three-phase AC flows through the multiple electromagnetic bodies, a moving magnetic field is generated to linearly drive the mover 3 with permanent magnets in the desired tangential direction along the rail. In addition, in the example of FIG1 , the normal direction of the rail surface 21 forming the annular rail in the horizontal plane is the horizontal direction, but the normal direction of the rail surface 21 can be the vertical direction or any other direction.

In the stator 2, a plurality of magnetic sensors (not shown in FIG. 1 ) are continuously or periodically buried in the positioning portion 22 disposed on the upper surface or the lower surface perpendicular to the guide rail surface 21 as position detection portions. The magnetic sensors are capable of measuring the position of a magnetic scale (not shown in FIG. 1 ) mounted on the mover 3 as a positioning object or a positioning scale. A magnetic sensor that uses a magnetic scale formed by a striped magnetic pattern or a magnetic scale with a constant pitch as a positioning object generally has a plurality of magnetic detection heads. By staggering the intervals between the plurality of magnetic detection heads with the intervals or periods of the magnetic pattern of the magnetic scale, the magnetic sensor can measure the position of the magnetic scale with high precision. In a typical magnetic sensor having two magnetic detection heads, for example, the interval between the two magnetic detection heads is offset from the magnetic pattern of the magnetic scale by 1/4 of the interval (phase offset by 90 degrees). In addition, the magnetic sensor may be provided on the mover 3 and the magnetic scale may be provided on the stator 2 in the opposite manner to the above. Furthermore, if the position of the mover 3 measured by the positioning unit 22 is differentiated by time, the speed of the mover 3 can be detected, and if the speed is differentiated by time, the acceleration of the mover 3 can be detected.

The position detection unit provided on the stator 2 and the positioning object or positioning scale mounted on the mover 3 are not limited to the magnetic type as described above, and may be optical or other types. In the case of the optical type, an optical scale formed by a pattern or scale with a constant spacing is mounted on the mover 3, and an optical sensor capable of optically reading the pattern of the optical scale is provided on the stator 2. In the magnetic or optical type, since the position detection unit measures the positioning object (magnetic scale or optical scale) non-contactly, it is possible to reduce the risk of failure of the position detection unit when the transported object transported by the mover 3 is scattered and enters the positioning portion (the upper surface of the stator 2). Among them, in the optical method, if the transported object such as liquid or powder that enters the measurement area covers the optical scale, the measurement accuracy will deteriorate. Therefore, if the magnetism of the transported object can be ignored, it is better to use the magnetic method, which does not deteriorate the measurement accuracy even if it enters the measurement area.

The mover 3 includes: a mover body 31, which is opposite to the guide rail surface 21 of the stator 2; a positioned portion 32, which extends horizontally from the upper portion of the mover body 31 and is opposite to the positioning portion 22 of the stator 2; and a conveying portion 33, which extends horizontally from the mover body 31 on the side opposite to the positioned portion 32 (the side away from the stator 2) and carries or fixes the conveyed object. The mover body 31 includes: one or more permanent magnets (not shown) that are opposite to the plurality of electromagnetic magnets buried in the guide rail surface 21 of the stator 2 along the guide rail. Since the moving magnetic field generated by the electromagnet of the stator 2 exerts a linear force or thrust in the tangential direction of the guide rail on the permanent magnet of the mover 3 and/or the electromagnet itself, the mover 3 is driven linearly along the guide rail surface 21 relative to the stator 2.

On the positioned portion 32 of the mover 3, a magnetic scale or an optical scale as a positioning object or a positioning scale is provided to face the position detection portion (magnetic sensor or optical sensor) provided on the positioning portion 22 of the stator 2. In the example of FIG. 1 in which the position detection portion is provided on the upper surface of the stator 2, the positioning object such as the magnetic scale is mounted on the lower surface of the positioned portion 32 of the mover 3. When the positioning part 22 and the positioned part 32 are magnetic, it is preferred that the guide surface 21 and the positioning part 22 are formed on different surfaces or separated parts in the stator 2, and the mover body 31 and the positioned part 32 are formed on different surfaces or separated parts in the mover 3 so that the magnetic field between the electromagnetic body of the guide surface 21 and the permanent magnet of the mover body 31 does not affect the magnetic positioning of the positioning part 22 and the positioned part 32.

In FIG1 , four movers 3A, 3B, 3C, and 3D are illustrated, but, for example, in a linear transport system 1 that transports a small amount of transported objects multiple times, it is also possible to assume that more than 1,000 movers 3 are required. In such cases, it often happens that two different positioning scales (i.e., movers 3) enter the detection range of two adjacent position detection units at the same time. In addition, two movers 3 (i.e., positioning scales) that are close to each other may also enter the detection range of a position detection unit at the same time. Even in such complex situations, each position detection unit must accurately detect the reference mark of the mover 3 described below, and be able to uniquely determine the mover 3 provided with each reference mark.

FIG. 2 schematically shows a positioning device 4 composed of a position detection unit and a positioning scale in a linear transport system 1. The positioning device 4 has a plurality of (five in the illustrated example) magnetic sensors S1 to S5 as position detection units, and the magnetic sensors S1 to S5 are buried or arranged on the guide rail surface 21 along the track direction of the stator 2 or the moving direction of the movers C1 and C2 (left-right direction in FIG. 2) in order to position the magnetic scales (hereinafter also referred to as magnetic scales C1 and C2 for convenience) mounted on the plurality of (two in the illustrated example) movers C1 and C2 as positioning scales.

The intervals between the magnetic sensors S1~S5 in the moving direction may be different from each other, but in this embodiment, an example is described in which all the intervals are equal. At this time, the intervals between the magnetic sensors S1~S5 in the moving direction are, for example, 30mm. In addition, the lengths of the magnetic scales C1 and C2 in the moving direction may also be different from each other, but in this embodiment, an example is described in which all the lengths are equal. At this time, the lengths of the magnetic scales C1 and C2 in the moving direction are, for example, 48mm. Thus, in this embodiment, the intervals between the magnetic sensors S1~S5 in the moving direction (30mm) are smaller than the lengths of the magnetic scales C1 and C2 in the moving direction (48mm).

The magnetic scale C1 has two ends E1L and E1R in the moving direction and a long scale body AB1 surrounded by the two ends E1L and E1R from both sides of the moving direction. A plurality of magnetic scales or magnetic patterns are formed on the scale body AB1 and are arranged at equal intervals along the moving direction. Each magnetic sensor S1~S5 that detects the magnetic scale of the scale body AB1 outputs a general A-phase and B-phase pulse in a known linear encoder. Typically, the phases of the A-phase pulse and the B-phase pulse differ by 90 degrees from each other. In addition, the same magnetic scales as those of the scale body AB1 can also be formed at the two ends E1L and E1R of the magnetic scale C1.

The length of each end E1L, E1R of the magnetic scale C1 in the moving direction is, for example, 8mm. At this time, the length of the scale body AB1 in the moving direction is 32mm, which is obtained by subtracting the total length of the two ends E1L, E1R (16mm) from the length of the magnetic scale C1 (48mm). Thus, in this embodiment, the interval (30mm) between each magnetic sensor S1~S5 in the moving direction is smaller than the length (32mm) of the scale body AB1 of the magnetic scale C1 in the moving direction.

A reference mark Z1 is provided as a reference mark on the mover C1 and/or the magnetic scale C1. Each magnetic sensor S1 to S5 that magnetically detects the reference mark Z1 outputs a general Z-phase pulse in a known linear encoder. The details will be described later, but the Z-phase pulse outputted according to the reference mark Z1 is used to determine the reference position of the mover C1. In the example shown in the figure, the reference mark Z1 is provided at the center of the magnetic scale C1 and/or the scale body AB1 in the moving direction. The distances (24 mm) between the reference mark Z1 and the ends of the magnetic scale C1 in the moving direction are smaller than the intervals (30 mm) between the plurality of magnetic sensors S1 to S5. In addition, the distance between the reference mark Z1 and the scale body AB1 at both ends in the moving direction (16mm) is smaller than the interval between the multiple magnetic sensors S1~S5 (30mm).

The description of the magnetic scale C1 above is also applicable to other magnetic scales such as the magnetic scale C2. However, the dimensions of the above parts and the positions of the reference marks are arbitrarily determined for each magnetic scale. Unless otherwise specified, the description of the magnetic scale C1 is also applicable to the magnetic scale C2, etc., and repeated descriptions of the magnetic scale C2, etc. are omitted.

Each magnetic sensor S1-S5 has a counting unit 51-55, which counts the magnetic scales of the A/B phase formed on the scale body AB1 and/or the two ends E1L and E1R of the magnetic scale C1. The increase and decrease direction of the count value in each counting unit 51-55 corresponds to the movement direction of the magnetic scale C1 (i.e., the mover C1) detected by each magnetic sensor S1-S5. For example, when the mover C1 moves from the left side to the right side in FIG. 2 , the count values in each counting unit 51 to 55 increase according to the number of A/B phase pulses output by each magnetic sensor S1 to S5, and when the mover C1 moves from the right side to the left side in FIG. 2 , the count values in each counting unit 51 to 55 decrease according to the number of A/B phase pulses output by each magnetic sensor S1 to S5.

When the mover C1 moves on the guide rail, the magnetic sensors S1 to S5 for positioning the magnetic scale C1 are switched in sequence. FIG3 schematically shows the situation in which the positioning body of the magnetic scale C1 moving from the left to the right is switched from the magnetic sensor S1 at the moving source to the magnetic sensor S2 at the moving destination. As shown in the figure, the switching of the magnetic sensors S1 and S2 is performed when the scale body AB1 of the magnetic scale C1 crosses the detection range of the two adjacent magnetic sensors S1 and S2. In the example shown in the figure, when the magnetic sensors S1 and S2 are located at positions SW1 and SW2 that are symmetrical with respect to the center of the magnetic scale C1 in the moving direction (reference mark Z1 position), the positioning subject of the magnetic scale C1 is switched from the magnetic sensor S1 to the magnetic sensor S2.

The first switching position SW1 is a position in the scale body AB1 at a predetermined distance from the boundary between the left end E1L and the scale body AB1, and the second switching position SW2 is a position in the scale body AB1 at a predetermined distance from the boundary between the right end E1R and the scale body AB1. In the illustrated example, the distance between the first switching position SW1 and the left end of the scale body AB1 and the distance between the second switching position SW2 and the right end of the scale body AB1 are, for example, 1 mm. In such cases, the distance between the first switching position SW1 and the center of the scale body AB1 and the distance between the second switching position SW2 and the center of the scale body AB1 are 15 mm, and the sum (30 mm) is consistent with the interval between the magnetic sensors S1 and S2.

When the positioning body of the magnetic scale C1 is switched from the magnetic sensor S1 to the magnetic sensor S2, the count value of the counting unit 51 of the magnetic sensor S1 at the moving source is replaced by the count value of the counting unit 52 of the magnetic sensor S2 at the moving destination. Hereinafter, the count value of each counting unit 51 to 55 when each magnetic sensor S1 to S5 detects the center of the magnetic scale C1 (reference mark Z1 position) is set to zero, the count value of each counting unit 51 to 55 when each magnetic sensor S1 to S5 detects the magnetic scale on the side opposite to the moving direction of the mover C1 (left side in FIG. 3) from the center of the magnetic scale C1 is set to positive, and the count value of each counting unit 51 to 55 when each magnetic sensor S1 to S5 detects the magnetic scale on the moving direction side of the mover C1 (right side in FIG. 3) from the center of the magnetic scale C1 is set to negative.

In the illustrated example, the position of the reference mark Z1 corresponds to the count value "0", the first switching position SW1 corresponds to, for example, the count value "+15,000", and the second switching position SW2 corresponds to, for example, the count value "-15,000". Hereinafter, the count value "+15,000" of the first switching position SW1 is also referred to as the switching count value, and the count value "-15,000" of the second switching position SW2 is also referred to as the starting count value. In the illustrated example, the switching count value and the starting count value differ only in positive and negative signs. In the state shown in the figure, when the first switching position SW1 of the magnetic scale C1 comes to the magnetic sensor S1, the switching count value "+15,000" of its counter 51 is converted to the starting count value "-15,000" of the counter 52 of the magnetic sensor S2 located at the second switching position SW2. After that, the magnetic sensor S2 becomes the positioning body of the magnetic scale C1, and its counter 52 counts from the starting count value "-15,000" to the next switching count value "+15,000" (towards the magnetic sensor S3).

The reference mark detection control unit 40 in FIG2 includes: a reference mark detection validation unit 41 that validates the detection of the reference mark Z1 performed by each magnetic sensor S1 to S5 according to the count value in each counting unit 51 to 55; and a reference mark detection invalidation unit 42 that invalidates the detection of the reference mark Z1 performed by each magnetic sensor S1 to S5 according to the count value in each counting unit 51 to 55.

Before explaining the detection control of the reference mark Z1 by the reference mark detection validating unit 41 and/or the reference mark detection invalidating unit 42, other embodiments are shown in FIG4 and FIG5. As shown in FIG4, when the mover C1 is used for the first time in the linear transport system 1, it is necessary to determine or register the reference position or initial position of the mover C1 by detecting the reference mark Z1 of the magnetic scale C1 by any one of the plurality of magnetic sensors (S1, S2 in the example of FIG4). Each magnetic sensor S1, S2 must reliably detect the reference mark Z1 and be able to determine that the reference mark Z1 is the mark of the mover C1. Therefore, in order to prevent the misdetection of the reference mark Z1 and/or the mover C1, each magnetic sensor S1, S2 is in principle incapable of detecting the reference mark Z1. The detection of the reference mark Z1 is only effective when the reference mark Z1 and the mover C1 can be detected reliably.

As shown in FIG4, it is assumed that the mover C1 whose initial position is not registered in the linear transport system 1 moves along the guide rail from the left to the right of the magnetic sensor S1. The position of the magnetic scale C1 in the state of FIG4 is not on any of the magnetic sensors S1 and S2, and is shown as "S1 left" in FIG5. In this "S1 left" state, since neither of the magnetic sensors S1 and S2 detects the magnetic scale of the A/B phase of the magnetic scale C1, the "S1-A/B phase" and "S2-A/B phase" in FIG5, which schematically show the count values of each counting unit 51 and 52 (FIG2), are both "0".

When the mover C1 moves from the state of FIG. 4 and at least the right end E1R of the magnetic scale C1 comes onto the magnetic sensor S1, the magnetic sensor S1 detects the magnetic scale of the A/B phase formed on the right end E1R and/or the scale body AB1, and the count value in the counting unit 51 increases according to the number of A/B phase pulses from the magnetic sensor S1. In the example of FIG. 5, when the "scale position" of the magnetic scale C1 switches from "S1 left" to "S1 up", the "S1-A/B phase" representing the count value of the counting unit 51 increases from "1" to "12". In the "S1 on" state, since the magnetic scale C1 is not on the magnetic sensor S2, the magnetic sensor S2 does not detect the magnetic scale of the A/B phase of the magnetic scale C1, so the "S2-A/B phase" representing the count value of the counter 52 remains at "0". In addition, in this embodiment, for the sake of simplicity, it is assumed that the count value "18" represents the full length of a magnetic scale, but the count value of each magnetic scale in the actual linear transport system 1 is very large, for example, as described above with respect to FIG. 3, it is about "30,000" ("-15,000" ~ "+15,000").

When the count value of "S1-A/B phase" in Figure 5 becomes "9", the "Z" that appears in the "S1-Z phase" column indicates that the reference mark Z1 has reached the magnetic sensor S1. However, as mentioned above, since the magnetic sensor S1 is in principle incapable of detecting the reference mark Z1 ("S1-Z detection" becomes "unable"), the reference mark Z1 is not detected when the count value of "S1-A/B phase" becomes "9".

During the period when the count value of "S1-A/B phase" in FIG. 5 is "13" to "18", the magnetic scale C1 is in the "S1&S2 on" state, which is located on both the magnetic sensors S1 and S2. Specifically, the portion of the magnetic scale C1 to the left of the reference mark Z1 (the left end E1L or the left portion of the scale body AB1) is located on the magnetic sensor S1, and the portion of the magnetic scale C1 to the right of the reference mark Z1 (the right end E1R or the right portion of the scale body AB1) is located on the magnetic sensor S2. In the "S1 & S2 on" state, since both magnetic sensors S1 and S2 detect the A/B phase magnetic scale of the magnetic scale C1, the "S1-A/B phase" and "S2-A/B phase" representing the count values of each counting unit 51 and 52 increase in the same manner.

In this embodiment, when "S1-A/B phase" and "S2-A/B phase" continuously increase and decrease a predetermined count value (in the example shown in the figure, a count value of "3") in the same direction at substantially the same time, the detection of the reference mark Z1 by the magnetic sensor on the side of the moving direction of the mover C1 in the increasing and decreasing direction is validated. In the example shown in the figure, since the increase of "13" to "15" of "S1-A/B phase" and the increase of "1" to "3" of "S2-A/B phase" continuously generate a count value of "3" at substantially the same time, the detection of the reference mark Z1 by the magnetic sensor S2 on the side of the moving direction from the left side to the right side of the mover C1 in the increasing direction (i.e., the right side) is validated. In this way, after the count value of "S2-A/B phase" reaches "4", "S2-Z detection" switches from "disabled" to "enabled".

In this state, when the count value of "S2-A/B phase" becomes "9", the reference mark Z1 comes to the magnetic sensor S2 ("Z" appears in the "S2-Z phase" column), so the reference mark Z1 is detected by the magnetic sensor S2, and the initial position of the mover C1 is registered in the linear transport system 1. In addition, at the moment when the count value of "S2-A/B phase" is "9", the magnetic scale C1 passes the right side of the magnetic sensor S1, so the "scale position" becomes "S2 on", indicating that the magnetic scale C1 is (only) located on the magnetic sensor S2, and the count value of "S1-A/B phase" remains unchanged at the maximum value "18".

As described above, in the embodiments of Figures 4 and 5, the detection of the reference mark Z1 by the magnetic sensor S2 on the moving direction side of the mover C1 is enabled only when the count values of two adjacent magnetic sensors S1 and S2 continuously change by a specified count value at approximately the same time and in the same direction. Therefore, the reference mark Z1 of the mover C1 detected simultaneously by the two magnetic sensors S1 and S2 can be accurately detected by the magnetic sensor S2 at the moving destination. However, when two movers approaching each other move at the same speed, the count values of two adjacent magnetic sensors that detect each mover individually change by a predetermined count value in the same direction at approximately the same time, so there is a possibility of erroneous detection of the reference mark and/or the mover. According to the present embodiment described below, the possibility of erroneous detection of the reference mark and/or the mover can be further reduced by the structure shown in FIG. 2 (particularly the reference mark detection validating unit 41 and/or the reference mark detection invalidating unit 42).

In FIG2 , the reference mark detection validation unit 41 validates the detection of the reference marks Z1 and Z2 by the other magnetic sensor S1 to S5 according to the count values in each counting unit 51 to 55, when the magnetic scales C1 and C2 move from the state of crossing the detection range of two adjacent magnetic sensors S1/S2, S2/S3, S3/S4, S4/S5 to outside the detection range of one of the magnetic sensors S1 to S5.

In the simple embodiment shown in FIG. 6 and FIG. 7 , the reference mark detection validation unit 41 validates the detection of the reference mark Z1 by the other magnetic sensor S2 on the moving direction side of the mover C1 based on the count values in the counting units 51 and 52 (not shown in FIG. 6 ) when the magnetic scale C1 moves from the state of spanning the detection range of two adjacent magnetic sensors S1/S2 to outside the detection range of one of the magnetic sensors S1 as shown by the dotted line.

As shown in FIG7, the reference mark detection validation unit 41 is similar to FIG5. When the count values of the counting units 51 and 52 in the two adjacent magnetic sensors S1 and S2 change in the same manner (in the illustrated example, when the count value of the magnetic sensor S1 increases to "13" to "15", the count value of the magnetic sensor S2 increases to "1" to "3"), it is determined that the magnetic scale C1 is in the "S1 & S2 on" state that spans the two adjacent detection ranges. The magnetic scale C1 in the "S1 & S2 on" state is located on both the magnetic sensors S1 and S2 as shown by the solid line in FIG6. At this time, the reference mark Z1 is located at a position clamped by the detection ranges of the two adjacent magnetic sensors S1 and S2.

As shown in FIG7 , the state of "S1 & S2 on" in which the magnetic scale C1 crosses two adjacent detection ranges continues until the count value of the magnetic sensor S1 becomes "18" and the count value of the magnetic sensor S2 becomes "6". When the count value of the magnetic sensor S1 remains at "18" and only the count value of the magnetic sensor S2 increases to "7", as shown by the dotted line in FIG6 , the mover C1 moves out of the detection range of one of the magnetic sensors S1 on the side opposite to the moving direction and becomes the state of "S2 on". Therefore, the reference mark detection validating unit 41 validates the detection of the reference mark Z1 by the other magnetic sensor S2 on the moving direction side of the mover C1 at the moment when only the count value of the magnetic sensor S2 increases to "7". In addition, the reference mark detection validation unit 41 can also validate the detection of the reference mark Z1 by another magnetic sensor S2 on the moving direction side of the mover C1 when the magnetic sensor S1 cannot detect the magnetic scale of the A/B phase of the magnetic scale C1.

At this time, the reference mark Z1 is still located in the position clamped by the detection range of the two adjacent magnetic sensors S1 and S2 as shown by the dotted line in FIG6 , so the mover C1 further moves in the same direction, so that the reference mark Z1 comes to the magnetic sensor S2. Specifically, when the count value of the magnetic sensor S2 becomes "9", the reference mark Z1 comes to the magnetic sensor S2 ("Z" appears in the "S2-Z phase" column), so the reference mark Z1 is detected by the magnetic sensor S2, and the initial position of the mover C1 is registered in the linear transport system 1. In the case where another magnetic sensor S2 on the moving direction side validated by the reference mark detection validating unit 41 with an S2 count value of "7" detects the reference mark Z1 with an S2 count value of "9", the reference mark detection invalidating unit 42 in Figure 2 invalidates the detection of the reference mark Z1 by the other magnetic sensor S2 after the S2 count value reaches "10" (making "S2-Z detection" "unable").

Next, the case where there are multiple movers is described. In such a case, two movers (i.e., magnetic scales) that are close to each other may enter the detection range of a magnetic sensor at the same time, so it is better to take measures in advance as shown in Figure 8 to prevent misdetection of each magnetic scale.

FIG8 schematically shows a state where two magnetic scales C1 and C2 approaching the minimum accessible distance simultaneously enter the detection range R of a magnetic sensor S1 to S5. In this example, the minimum accessible distance between the two magnetic scales C1 and C2 (the distance between the right end of the magnetic scale C1 and the left end of the magnetic scale C2 in the illustrated state) is 2 mm, and the length of the detection range R of the magnetic sensors S1 to S5 in the track direction (left-right direction in FIG8) is 5 mm. As described above, the right end E1R of the magnetic scale C1 and the left end E2L of the magnetic scale C2 have A/B phase magnetic scales formed in the same manner as the scale body AB1 of the magnetic scale C1 and the scale body AB2 of the magnetic scale C2, so in the state shown in the figure, the magnetic sensors S1~S5 will simultaneously detect the A/B phase magnetic scales of the right end E1R and the A/B phase magnetic scales of the left end E2L. In such a case, the magnetic sensors S1~S5 cannot distinguish the two magnetic scales C1 and C2 for detection.

In order to prevent the misdetection of the two magnetic scales C1 and C2 that are so close, a shielding member B1R and/or a shielding member B2L are provided to shield the right end E1R of the magnetic scale C1 and/or the left end E2L of the magnetic scale C2 from the detection range R of the magnetic sensors S1 to S5.

The shielding member B1R shields at least the A/B phase magnetic scale disposed on the right end side away from the scale body AB1 at the right end E1R of the magnetic scale C1. Specifically, as described above, the right end side portion of the right end E1R having a total length of 8 mm is shielded by the shielding member B1R. If the length of the shielding member B1R in the track direction is set to be greater than the length of the detection range R of the magnetic sensors S1 to S5 in the track direction (5 mm), the shielding member B1R can shield the detection range R of the magnetic sensors S1 to S5 alone, thereby preventing the magnetic scale C1 and the magnetic scale C2 from being detected simultaneously. Furthermore, if the length of the shielding member B1R in the track direction is set to be greater than the length (3 mm) obtained by subtracting the minimum approachable distance (2 mm) of the movers C1 and C2 from the length (5 mm) of the detection range R of the magnetic sensors S1 to S5 in the track direction, the shielding member B1R can actually shield the detection range R of the magnetic sensors S1 to S5 alone, thereby preventing the magnetic scale C1 and the magnetic scale C2 from being detected at the same time. Furthermore, if the length of the shielding member B1R in the track direction is set to be at least half (1.5 mm) of the length (3 mm) obtained by subtracting the minimum approachable distance (2 mm) of the movers C1 and C2 from the length (5 mm) of the detection range R of the magnetic sensors S1 to S5 in the track direction, then the detection range R of the magnetic sensors S1 to S5 can be substantially shielded together with the shielding member B2L of the same length, thereby preventing the magnetic scale C1 and the magnetic scale C2 from being detected at the same time.

The shielding member B2L shields at least the A/B phase magnetic scale disposed on the left end side away from the scale body AB2 at the left end E2L of the magnetic scale C2. Specifically, as described above, the left end side portion of the left end E2L having a total length of 8 mm is shielded by the shielding member B2L. If the length of the shielding member B2L in the track direction is set to be greater than the length of the detection range R of the magnetic sensors S1 to S5 in the track direction (5 mm), the shielding member B2L can shield the detection range R of the magnetic sensors S1 to S5 alone, thereby preventing the magnetic scale C2 from being detected at the same time as the magnetic scale C1. Furthermore, if the length of the shielding member B2L in the track direction is set to be greater than the length (3mm) obtained by subtracting the minimum approachable distance (2mm) of the movers C1 and C2 from the length (5mm) of the detection range R of the magnetic sensors S1~S5 in the track direction, the shielding member B2L can actually shield the detection range R of the magnetic sensors S1~S5 alone, thereby preventing the magnetic scale C2 and the magnetic scale C1 from being detected at the same time. Furthermore, if the length of the shielding member B2L in the track direction is set to be at least half (1.5 mm) of the length (3 mm) obtained by subtracting the minimum approachable distance (2 mm) of the movers C1 and C2 from the length (5 mm) of the detection range R of the magnetic sensors S1 to S5 in the track direction, then the detection range R of the magnetic sensors S1 to S5 can be substantially shielded together with the shielding member B1R of the same length, thereby preventing the magnetic scale C2 from being detected at the same time as the magnetic scale C1.

In the magnetic scale C1, a shielding member similar to the shielding member B1R at the right end (or the shielding member B2L at the left end of the magnetic scale C2) may be provided at the left end not shown, or the shielding member may be provided only at the left end. Similarly, in the magnetic scale C2, a shielding member similar to the shielding member B2L at the left end (or the shielding member B1R at the right end of the magnetic scale C1) may be provided at the right end not shown, or the shielding member may be provided only at the right end.

The shielding member B1R and/or the shielding member B2L are formed of a ferromagnetic material that magnetically shields at least one end of the magnetic scale C1 and/or the magnetic scale C2 from the magnetic sensors S1 to S5. Examples of ferromagnetic materials include metals or alloys such as iron, cobalt, nickel, gadolinium, and manganese. In addition, when an optical scale is used as a positioning scale instead of a magnetic scale, the shielding member can be formed by using an optical shielding material as a light shielding material of an optical sensor of a position detection unit. As described above, by taking measures such as FIG. 8, even if the ends of the positioning scales of two movers approaching each other enter the detection range of a position detection unit at the same time, the shielding member provided at at least one of the ends can prevent the two positioning scales from being mistakenly detected by the position detection unit at the same time.

Next, a plurality of embodiments in which two movers approaching each other move at the same speed and may erroneously detect reference marks and/or movers in the embodiments of FIGS. 4 and 5 (an embodiment not using the reference mark detection validation unit 41 and/or the reference mark detection invalidation unit 42) are described.

In the first embodiment shown in FIG. 9 and FIG. 10, in the initial state shown in FIG. 9 (a state in which the movers C1 and C2 without registering the initial position start to move to the right), the mover C1 is located on both the magnetic sensors S2 and S3, and the mover C2 is located on the magnetic sensor S4. As shown in FIG. 10, the reference mark detection validation unit 41 validates the detection of the reference mark Z1 by the other magnetic sensor S3 on the moving direction side of the mover C1 based on the count values in the counting units 52 and 53 when the magnetic scale C1 moves from the state of crossing the detection range of the two adjacent magnetic sensors S2/S3 to outside the detection range of one of the magnetic sensors S2.

In this state, when the mover C1 further moves in the same direction, the reference mark Z1 reaches the magnetic sensor S3, and the reference mark Z1 is detected by the magnetic sensor S3, and the initial position of the mover C1 is registered in the linear transport system 1. After the reference mark Z1 is detected by the magnetic sensor S3, the reference mark detection invalidation unit 42 invalidates the detection of the reference mark Z1 by the magnetic sensor S3. In addition, the magnetic scale C1 then moves from the state of crossing the detection range of two adjacent magnetic sensors S3/S4 to outside the detection range of one of the magnetic sensors S3. However, since the reference mark Z1 of the magnetic scale C1 has been detected by the magnetic sensor S3, the detection of the reference mark Z1 by the magnetic sensor S4 is not effective.

On the other hand, the reference mark detection validation unit 41 validates the detection of the reference mark Z2 by the other magnetic sensor S5 on the moving direction side of the mover C2, based on the count values in the counting units 54 and 55, when the magnetic scale C2 moves from the state of straddling the detection ranges of the two adjacent magnetic sensors S4/S5 to outside the detection range of one of the magnetic sensors S4. In this state, when the mover C2 further moves in the same direction, the reference mark Z2 comes onto the magnetic sensor S5, and the reference mark Z2 is detected by the magnetic sensor S5, and the initial position of the mover C2 is registered in the linear transport system 1. After the reference mark Z2 is detected by the magnetic sensor S5, the reference mark detection invalidation unit 42 invalidates the detection of the reference mark Z2 by the magnetic sensor S5. As described above, even when two movers C1 and C2 close to each other move at the same speed, the reference marks Z1 and Z2 of each mover C1 and C2 can be accurately detected.

In the second embodiment shown in FIG. 11 and FIG. 12, in the initial state shown in FIG. 11, the mover C1 is located on the magnetic sensor S2, and the mover C2 is located on both the magnetic sensors S3 and S4. As shown in FIG. 12, the reference mark detection validation unit 41 validates the detection of the reference mark Z2 by the other magnetic sensor S4 on the moving direction side of the mover C2 based on the count values in the counting units 53 and 54 when the magnetic scale C2 moves from the state of crossing the detection range of two adjacent magnetic sensors S3/S4 to outside the detection range of one of the magnetic sensors S3.

In this state, when the mover C2 further moves in the same direction, the reference mark Z2 reaches the magnetic sensor S4, and the reference mark Z2 is detected by the magnetic sensor S4, and the initial position of the mover C2 is registered in the linear transport system 1. After the reference mark Z2 is detected by the magnetic sensor S4, the reference mark detection invalidation unit 42 invalidates the detection of the reference mark Z2 by the magnetic sensor S4. In addition, the magnetic scale C2 then moves from the state of crossing the detection range of two adjacent magnetic sensors S4/S5 to outside the detection range of one of the magnetic sensors S4. However, since the reference mark Z2 of the magnetic scale C2 has been detected by the magnetic sensor S4, the detection of the reference mark Z2 by the magnetic sensor S5 is not effective.

On the other hand, the reference mark detection validation unit 41 validates the detection of the reference mark Z1 by the other magnetic sensor S3 on the moving direction side of the mover C1 based on the count values in the counting units 52 and 53 when the magnetic scale C1 moves from the state of crossing the detection range of the two adjacent magnetic sensors S2/S3 to outside the detection range of one of the magnetic sensors S2. In this state, when the mover C1 further moves in the same direction, the reference mark Z1 comes to the magnetic sensor S3, so the reference mark Z1 is detected by the magnetic sensor S3, and the initial position of the mover C1 is registered in the linear transport system 1. After the reference mark Z1 is detected by the magnetic sensor S3, the reference mark detection invalidation unit 42 invalidates the detection of the reference mark Z1 by the magnetic sensor S3. As described above, even when two movers C1 and C2 close to each other move at the same speed, the reference marks Z1 and Z2 of each mover C1 and C2 can be accurately detected.

In the third embodiment shown in FIG. 13 and FIG. 14, in the initial state shown in FIG. 13, the mover C1 is located on both the magnetic sensors S1 and S2, and the mover C2 is located on both the magnetic sensors S3 and S4. As shown in FIG. 14, the reference mark detection validation unit 41 validates the detection of the reference mark Z1 by the other magnetic sensor S2 on the moving direction side of the mover C1 based on the count values in the counting units 51 and 52 when the magnetic scale C1 moves from the state of crossing the detection range of the two adjacent magnetic sensors S1/S2 to outside the detection range of one of the magnetic sensors S1.

In this state, when the mover C1 further moves in the same direction, the reference mark Z1 reaches the magnetic sensor S2, and the reference mark Z1 is detected by the magnetic sensor S2, and the initial position of the mover C1 is registered in the linear transport system 1. After the reference mark Z1 is detected by the magnetic sensor S2, the reference mark detection invalidation unit 42 invalidates the detection of the reference mark Z1 by the magnetic sensor S2. In addition, the magnetic scale C1 then moves from the state of crossing the detection range of two adjacent magnetic sensors S2/S3 to outside the detection range of one of the magnetic sensors S2. However, since the reference mark Z1 of the magnetic scale C1 has been detected by the magnetic sensor S2, the detection of the reference mark Z1 by the magnetic sensor S3 is not effective.

On the other hand, the reference mark detection validation unit 41 validates the detection of the reference mark Z2 by the other magnetic sensor S4 on the moving direction side of the mover C2, based on the count values in the counting units 53 and 54, when the magnetic scale C2 moves from the state of crossing the detection range of two adjacent magnetic sensors S3/S4 to outside the detection range of one of the magnetic sensors S3.

In this state, when the mover C2 further moves in the same direction, the reference mark Z2 reaches the magnetic sensor S4, and the reference mark Z2 is detected by the magnetic sensor S4, and the initial position of the mover C2 is registered in the linear transport system 1. After the reference mark Z2 is detected by the magnetic sensor S4, the reference mark detection invalidation unit 42 invalidates the detection of the reference mark Z2 by the magnetic sensor S4. In addition, although the diagram is omitted, the magnetic scale C2 later moves from the state of crossing the detection range of two adjacent magnetic sensors S4/S5 to outside the detection range of one of the magnetic sensors S4. However, since the reference mark Z2 of the magnetic scale C2 has been detected by the magnetic sensor S4, the detection of the reference mark Z2 by the magnetic sensor S5 is not effective. As described above, even when the two movers C1 and C2 close to each other move at the same speed, the reference marks Z1 and Z2 of each mover C1 and C2 can be detected reliably.

In the above-mentioned first to third embodiments, the moving direction of each mover C1, C2 is constant, but even when the moving direction of each mover C1, C2 changes, the reference marks Z1, Z2 of each mover C1, C2 can be accurately detected. For example, after the reference mark detection validation unit 41 validates the other (e.g., right) magnetic sensor, before the other magnetic sensor detects the reference marks Z1, Z2, when the magnetic scales C1, C2 return to a state spanning the detection range of one (e.g., left) magnetic sensor and the other magnetic sensor and then move outside the detection range of the other magnetic sensor, the reference mark detection validation unit 41 validates the detection of the reference marks Z1, Z2 by the one magnetic sensor.

At this time, after the reference mark detection validation unit 41 validates the other magnetic sensor, the reference mark detection invalidation unit 42 can invalidate the detection of the reference marks Z1, Z2 by the other magnetic sensor when the magnetic scales C1, C2 return to a state spanning the detection range of one of the magnetic sensors and the other magnetic sensor and move outside the detection range of the other magnetic sensor. Alternatively, the reference mark detection invalidation unit 42 may invalidate the detection of the reference marks Z1, Z2 by the other magnetic sensor when the magnetic scales C1, C2 return to a state spanning the detection range of one magnetic sensor and the other magnetic sensor after the other magnetic sensor is validated by the reference mark detection validating unit 41 and before the other magnetic sensor detects the reference marks Z1, Z2.

The present invention has been described above based on the implementation method. The implementation method is an example, and those skilled in the art should understand that various modifications can be made to the combination of the various components and the various processing steps, and such modifications are also within the scope of the present invention.

In the embodiment, a linear transport system that drives the mover based on the magnetic force between the permanent magnets provided on the mover and the electromagnetic magnets provided on the stator is exemplified, but the present invention can be applied to any driving device based on any principle other than magnetism (e.g., electricity, fluid).

In addition, the functional structure of each device described in the implementation method can be realized by hardware resources or software resources, or by the cooperation of hardware resources and software resources. As hardware resources, processors, ROM, RAM, and other LSIs can be used. As software resources, operating systems, applications, and other programs can be used.

This application claims priority based on Japanese Patent Application No. 2022-032726 filed on March 3, 2022. The entire contents of the Japanese application are incorporated herein by reference.

21: Guide rail surface

AB1: Scale body

AB2: Scale body

B1R: Shielding components

B2L: Shielding components

C1: Magnetic scale (motor)

C2: Magnetic scale (motor)

E1R: End

E2L: End

R: Detection range

S1~S5: Magnetic sensor

Claims (10)

A magnetic scale is mounted on a mover and positioned by a magnetic sensor disposed on a track of the mover; the magnetic scale has: a shielding member that shields at least one end of the magnetic scale from the magnetic sensor. As in claim 1, the magnetic scale, wherein the magnetic sensor is disposed at two ends of the magnetic scale. For example, in the magnetic scale of claim 1 or claim 2, the length of the shielding member in the track direction of the mover is such that the detection range of the magnetic sensor is greater than the length in the track direction. For example, in the magnetic scale of claim 1 or claim 2, the length of the shielding member in the track direction of the mover is greater than the length obtained by subtracting the minimum approachable distance of the plurality of movers from the length of the detection range of the magnetic sensor in the track direction. For example, in the magnetic scale of claim 1 or claim 2, the length of the shielding member in the track direction of the mover is more than half of the length obtained by subtracting the minimum approachable distance of the plurality of movers from the length of the detection range of the magnetic sensor in the track direction. A magnetic scale as claimed in claim 1 or claim 2, wherein the shielding member is formed by a ferromagnetic material that magnetically shields at least one end from the magnetic sensor. As in claim 1 or claim 2, the magnetic scale is arranged in plurality along the track direction of the mover; the magnetic scale comprises: a scale body having a length in the track direction greater than the interval between the plurality of magnetic sensors, and two end portions surrounding the two ends of the scale body in the track direction from both sides; the shielding member shields at least one end of the two end portions away from the scale body from the magnetic sensor. As in claim 7, a magnetic scale, wherein a plurality of scales detected by the magnetic sensor are arranged on the scale body and the two ends along the track direction; and the shielding member shields the scales arranged on the end side of at least one of the two ends from the magnetic sensor. A mover is provided with a magnetic scale mounted thereon, the magnetic scale is positioned by a magnetic sensor disposed on a track of the mover, and has a shielding member for shielding at least one end from the magnetic sensor. A driving device comprises: a plurality of movers, which are driven along a track; a magnetic sensor, which is arranged on the track to detect the position of the plurality of movers; and a plurality of magnetic scales, which are mounted on the plurality of movers, and are positioned by the magnetic sensor, and have a shielding member that shields at least one end from the magnetic sensor.

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