Positioning scale, mover, drive unit

Abstract

To provide a positioning scale and the like which can be effectively detected.SOLUTION: Magnetic scales C1, C2 are attached to a movable element and magnetically positioned by magnetic sensors S1-S5 arranged on a locus of the movable element. Shielding members B1R, B2L for magnetically shielding the magnetic sensors S1-S5 are provided on at least one ends E1R, E2L of the magnetic scales C1, C2. The length in the locus direction of the shielding members B1R, B2L is equal to or greater than the half of the length obtained by subtracting the minimum approachable distance of a plurality of movable elements from the length in the locus direction of a detection range R of the magnetic sensors S1-S5. The shielding members B1R, B2L are formed by a ferromagnetic material which magnetically shields at least one ends E1R, E2R of the magnetic scales C1, C2 from the magnetic sensors S1-S5.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a drive device or the like that moves a mover along a track. [Background technology]

[0002] Patent Document 1 discloses a linear transport system as a drive device that moves a mover along a track. A plurality of magnetic sensors arranged along the track measure the position of a magnetic scale (i.e., the mover) attached to the mover. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-164396 Summary of the Invention [Problem to be solved by the invention]

[0004] When multiple movers are present in the linear transport system of Patent Document 1, there is a possibility that two movers (i.e., magnetic scales) that are close to each other may simultaneously enter the detection range of one magnetic sensor, in which case the magnetic sensor will not be able to distinguish between the two magnetic scales.

[0005] The present invention has been made in view of the above circumstances, and has an object to provide a positioning scale and the like that can be detected effectively. [Means for solving the problem]

[0006] In order to solve the above problem, one embodiment of the positioning scale of the present invention is a positioning scale that is attached to a movable element and is positioned by a position detection unit that is arranged on the orbit of the movable element, and is provided with a shielding member that shields at least one end from the position detection unit.

[0007] According to this aspect, even if the ends of the positioning scales of two movable elements that are close to each other simultaneously enter the detection range of the position detection unit, erroneous detection of the positioning scales can be prevented by the shielding member provided on at least one of the ends.

[0008] Another aspect of the present invention is a mover, to which a positioning scale is attached, the position of which is measured by a position detecting unit disposed on the orbit of the mover, the positioning scale having a shielding member that shields at least one end of the positioning scale from the position detecting unit.

[0009] Yet another aspect of the present invention is a drive device comprising: a plurality of movers driven along a track; a position detection unit disposed on the track and detecting positions of the plurality of movers; and a plurality of positioning scales attached to the plurality of movers and having positions measured by the position detection unit, the plurality of positioning scales including a shielding member that shields at least one end from the position detection unit.

[0010] Any combination of the above components and any conversion of these expressions into methods, devices, systems, recording media, computer programs, etc. are also encompassed by the present invention. [Effects of the Invention]

[0011] According to the present invention, the positioning scale can be detected effectively. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view showing the overall structure of a linear transport system. [Figure 2] 1 is a schematic diagram illustrating a positioning device configured by a position detection unit and a positioning scale in a linear transport system. [Figure 3] 10A and 10B show a schematic diagram of a state in which the position measurement subject of a moving magnetic scale is switched from a magnetic sensor at the source of the movement to a magnetic sensor at the destination of the movement. [Figure 4] 10 illustrates an embodiment that does not utilize a fiducial mark sensing enabler and / or a fiducial mark sensing disabler. [Figure 5] 10 illustrates an embodiment that does not utilize a fiducial mark sensing enabler and / or a fiducial mark sensing disabler. [Figure 6] An embodiment utilizing a fiducial mark sensing enabler and / or a fiducial mark sensing disabler is shown. [Figure 7] An embodiment utilizing a fiducial mark sensing enabler and / or a fiducial mark sensing disabler is shown. [Figure 8] This diagram shows a schematic diagram of two magnetic scales approaching to the minimum approachable distance and simultaneously entering the detection range of one magnetic sensor. [Figure 9] A first embodiment is shown in which multiple movers move at a uniform speed. [Figure 10] A first embodiment is shown in which multiple movers move at a uniform speed. [Figure 11] A second embodiment is shown in which multiple movers move at a uniform speed. [Figure 12] A second embodiment is shown in which multiple movers move at a uniform speed. [Figure 13] A third embodiment is shown in which multiple movers move at a uniform speed. [Figure 14] A third embodiment is shown in which multiple movers move at a uniform speed. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, a mode for carrying out the present invention (hereinafter also referred to as an embodiment) will be described in detail with reference to the drawings. In the description and / or drawings, identical or equivalent components, members, processes, etc. will be assigned the same reference numerals, and redundant explanations will be omitted. The scale and shape of each part shown in the drawings are set for convenience to simplify the explanation, and should not be interpreted as limiting unless otherwise specified. The embodiment is an example and does not limit the scope of the present invention in any way. All features and combinations thereof described in the embodiment are not necessarily essential to the present invention.

[0014] FIG. 1 is a perspective view showing the overall structure of a linear conveyance system 1, which is one embodiment of a driving device according to the present invention. The linear conveyance system 1 includes a stator 2 that forms a circular rail or track, and multiple movers 3A, 3B, 3C, and 3D (hereinafter collectively referred to as movers 3) that are driven relative to the stator 2 and move along the rail. An electromagnet or coil provided on the stator 2 and a permanent magnet provided on the mover 3 face each other, forming a linear motor along the circular rail. The rail formed by the stator 2 is not limited to a circular shape and may have any shape. For example, the rail may be straight or curved, or one rail may branch into multiple rails, or multiple rails may merge into one rail. The installation direction of the rail formed by the stator 2 is also arbitrary. In the example of FIG. 1, the rail is arranged in a horizontal plane, but the rail may also be arranged in a vertical plane, or in a plane or curved surface at any inclination angle.

[0015] The stator 2 has a rail surface 21 whose normal direction is the horizontal direction. The rail surface 21 extends in a strip-like shape along the rail formation direction. When a circular rail is formed as in the example of Figure 1, the rail surface 21 becomes an endless strip with both ends (virtual) connected. On the rail surface 21, which can form a rail of any shape, multiple drive modules (not shown) equipped with electromagnets are embedded or arranged continuously or periodically along the rail. The electromagnets in the drive modules generate a magnetic field that exerts a driving force along the rail on the permanent magnets of the mover 3 and / or the electromagnets themselves. Specifically, when a drive current such as three-phase AC is applied to these multiple electromagnets, a moving magnetic field is generated that linearly drives the mover 3 equipped with the permanent magnets in a desired tangential direction along the rail. Note that in the example of Figure 1, the normal direction of the rail surface 21, which forms the circular rail in a horizontal plane, is horizontal, but the normal direction of the rail surface 21 may be vertical or any other direction.

[0016] In the stator 2, the positioning unit 22, which is provided on the upper or lower surface perpendicular to the rail surface 21, has multiple magnetic sensors (not shown in FIG. 1) embedded continuously or periodically as position detection units capable of measuring the position of a magnetic scale (not shown in FIG. 1) attached to the mover 3 as a positioning target or positioning scale. A magnetic sensor that measures the position of a magnetic scale formed by a striped magnetic pattern or magnetic graduations with a constant pitch generally has multiple magnetic detection heads. By shifting the spacing between the multiple magnetic detection heads with respect to the pitch or period 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 with two magnetic detection heads, for example, the spacing between the two magnetic detection heads is shifted by 1 / 4 pitch with respect to the magnetic pattern of the magnetic scale (90 degrees out of phase). Note that the magnetic sensor may be provided on the mover 3 and the magnetic scale on the stator 2, inversely. Furthermore, the speed of the mover 3 can be detected by differentiating the position of the mover 3 measured by the positioning unit 22 with respect to time, and the acceleration of the mover 3 can be detected by differentiating the speed with respect to time.

[0017] The position detection unit provided on the stator 2 and the positioning target or positioning scale attached to the mover 3 are not limited to the magnetic type described above, but may also be optical or other types. In the optical type, an optical scale formed by stripes or graduations with a fixed pitch is attached to the mover 3, and an optical sensor capable of optically reading the stripes on the optical scale is provided on the stator 2. In the magnetic and optical types, the position detection unit measures the positioning target (magnetic scale or optical scale) without contact, which reduces the risk of the position detection unit malfunctioning if an object being transported by the mover 3 scatters and enters the positioning location (the upper surface of the stator 2). However, with optical types, positioning accuracy deteriorates if the optical scale is covered by the transported object, such as liquid or powder, that enters the positioning location. Therefore, for transported objects with negligible magnetism, a magnetic type is preferable, as it does not deteriorate positioning accuracy even if the object enters the positioning location.

[0018] The mover 3 comprises a mover body 31 facing the rail surface 21 of the stator 2, a positioned unit 32 that extends horizontally from the top of the mover body 31 and faces the positioning unit 22 of the stator 2, and a transport unit 33 that extends horizontally from the mover body 31 on the opposite side (the side farther from the stator 2) from the positioned unit 32 and on which a transported object is placed or fixed. The mover body 31 comprises one or more permanent magnets (not shown) that face a plurality of electromagnets embedded in the rail surface 21 of the stator 2 along the rail. The moving magnetic field generated by the electromagnets of the stator 2 applies a linear power or propulsion force in the tangential direction of the rail to the permanent magnets of the mover 3 and / or the electromagnets themselves, so that the mover 3 is linearly driven along the rail surface 21 relative to the stator 2.

[0019] A magnetic scale or optical scale serving as the positioning target or positioning scale is provided on the positioned unit 32 of the mover 3 so as to face the position detection unit (magnetic sensor or optical sensor) provided on the positioning unit 22 of the stator 2. In the example of FIG. 1 where the position detection unit is provided on the upper surface of the stator 2, the positioning target such as the magnetic scale is attached to the lower surface of the positioned unit 32 of the mover 3. When the positioning unit 22 and the positioned unit 32 are magnetic, it is preferable that the rail surface 21 and the positioning unit 22 are formed on different surfaces or at separate locations on the stator 2, and that the mover body 31 and the positioned unit 32 are formed on different surfaces or at separate locations on the mover 3, so that the magnetic field between the electromagnets on the rail surface 21 and the permanent magnets on the mover body 31 does not affect the magnetic positioning of the positioning unit 22 and the positioned unit 32.

[0020] While FIG. 1 illustrates four movers 3A, 3B, 3C, and 3D, it is conceivable that, for example, in a linear transport system 1 that transports a large number of small loads, more than 1,000 movers 3 may be required. In such cases, it is common for two different positioning scales (i.e., movers 3) to simultaneously enter the detection range of two adjacent position detection units. It is also possible that two movers 3 (i.e., positioning scales) that are close to each other may simultaneously enter the detection range of a single position detection unit. Even in such complex cases, each position detection unit must be able to reliably detect the reference marks of the movers 3 described below and uniquely identify the movers 3 to which each reference mark is attached.

[0021] 2 is a schematic diagram of a positioning device 4 configured with a position detection unit and a positioning scale in the linear conveyance system 1. The positioning device 4 includes a plurality of (five in the illustrated example) magnetic sensors S1 to S5 as position detection units that are embedded or arranged on the rail surface 21 along the track direction of the stator 2 or the movement direction of the movers C1 and C2 (the left-right direction in FIG. 2) in order to measure the positions of magnetic scales (hereinafter also referred to as magnetic scales C1 and C2 for convenience) that serve as positioning scales attached to a plurality of (two in the illustrated example) movers C1 and C2.

[0022] The intervals between the magnetic sensors S1 to S5 in the movement direction may be different from one another, but in this embodiment, an example will be described in which all the intervals are equal. In this case, the intervals between the magnetic sensors S1 to S5 in the movement direction are, for example, 30 mm. Furthermore, the lengths of the magnetic scales C1 and C2 in the movement direction may also be different from one another, but in this embodiment, an example will be described in which all the lengths are equal. In this case, the length of each magnetic scale C1 and C2 in the movement direction is, for example, 48 mm. Thus, in this embodiment, the intervals between the magnetic sensors S1 to S5 in the movement direction (30 mm) are shorter than the length of each magnetic scale C1 and C2 in the movement direction (48 mm).

[0023] The magnetic scale C1 has opposite ends E1L and E1R in the direction of movement and a long scale body AB1 sandwiched between the opposite ends E1L and E1R in the direction of movement. A large number of magnetic graduations or magnetic patterns are formed on the scale body AB1 at equal intervals along the direction of movement. Each of the magnetic sensors S1 to S5 detects the magnetic graduations on the scale body AB1 and outputs A-phase and B-phase pulses, which are common in known linear encoders. Typically, the A-phase pulse and the B-phase pulse are 90 degrees out of phase with each other. Note that the opposite ends E1L and E1R of the magnetic scale C1 may also have magnetic graduations similar to those on the scale body AB1.

[0024] The length of each end E1L, E1R of the magnetic scale C1 in the movement direction is, for example, 8 mm. In this case, the length of the scale main body AB1 in the movement direction is 32 mm, which is obtained by subtracting the total length of both end portions E1L, E1R, 16 mm, from the length of the magnetic scale C1, 48 mm. Thus, in this embodiment, the spacing (30 mm) between each of the magnetic sensors S1 to S5 in the movement direction is shorter than the length (32 mm) of the scale main body AB1 of the magnetic scale C1 in the movement direction.

[0025] A reference mark Z1 is provided on the mover C1 and / or magnetic scale C1 as a reference mark. Each magnetic sensor S1 to S5 magnetically detects the reference mark Z1 and outputs a Z-phase pulse, which is typical of known linear encoders. As will be described in detail later, the Z-phase pulse output in response to the reference mark Z1 is used to identify the reference position of the mover C1. In the illustrated example, the reference mark Z1 is provided at the center of the magnetic scale C1 and / or scale main body AB1 in the movement direction. The distance (24 mm) between the reference mark Z1 and both ends of the magnetic scale C1 in the movement direction is smaller than the spacing (30 mm) between the multiple magnetic sensors S1 to S5. Furthermore, the distance (16 mm) between the reference mark Z1 and both ends of the scale main body AB1 in the movement direction is smaller than the spacing (30 mm) between the multiple magnetic sensors S1 to S5.

[0026] The above explanation of magnetic scale C1 also applies to other magnetic scales such as magnetic scale C2. However, the dimensions of each of the above components and the positions of the reference marks are determined arbitrarily for each magnetic scale. Unless otherwise specified below, the explanation of magnetic scale C1 also applies to magnetic scale C2, etc., and duplicate explanations of magnetic scale C2, etc. will be omitted.

[0027] Each of the magnetic sensors S1 to S5 includes a counter 51 to 55 that counts the A- and B-phase magnetic graduations formed on the scale body AB1 and / or both end portions E1L and E1R of the magnetic scale C1. The direction of increase or decrease in the count value in each of the counters 51 to 55 corresponds to the direction of movement of the magnetic scale C1 (i.e., the mover C1) detected by each of the magnetic sensors S1 to S5. For example, when the mover C1 moves from left to right in FIG. 2, the count value in each of the counters 51 to 55 increases in accordance with the number of A- and B-phase pulses output by each of the magnetic sensors S1 to S5, and when the mover C1 moves from right to left in FIG. 2, the count value in each of the counters 51 to 55 decreases in accordance with the number of A- and B-phase pulses output by each of the magnetic sensors S1 to S5.

[0028] As the mover C1 moves along the rail, the magnetic sensors S1 to S5 that measure the position of the magnetic scale C1 are switched in sequence. FIG. 3 schematically shows how the positioning entity of the magnetic scale C1 that moves from left to right switches from magnetic sensor S1 at the source of movement to magnetic sensor S2 at the destination of movement. As shown in the figure, the switching between magnetic sensors S1 and S2 is performed when the scale body AB1 of the magnetic scale C1 straddles the detection ranges of the two adjacent magnetic sensors S1 and S2. In the example shown in the figure, the positioning entity of the magnetic scale C1 is switched from magnetic sensor S1 to magnetic sensor S2 at the timing when the magnetic sensors S1 and S2 are at positions SW1 and SW2 that are symmetrical with respect to the center of the movement direction of the magnetic scale C1 (the position of the reference mark Z1).

[0029] The first switching position SW1 is a position within the scale body AB1 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 within the scale body AB1 a predetermined distance from the boundary between the right end E1R and the scale body AB1. In the example shown, the distance from the left end of the scale body AB1 to the first switching position SW1 and the distance from the right end of the scale body AB1 to the second switching position SW2 is, for example, 1 mm. In this case, the distance from the center of the scale body AB1 to the first switching position SW1 and the distance from the center of the scale body AB1 to the second switching position SW2 is 15 mm, and the sum of these distances (30 mm) matches the spacing between the magnetic sensors S1 and S2.

[0030] When the positioning subject of the magnetic scale C1 switches from magnetic sensor S1 to magnetic sensor S2, the count value of the counting unit 51 of the source magnetic sensor S1 is taken over as the count value of the counting unit 52 of the destination magnetic sensor S2. In the following, the count value of each of the counting units 51 to 55 when each of the magnetic sensors S1 to S5 detects the center of the magnetic scale C1 (the position of the reference mark Z1) is set to zero, the count value of each of the counting units 51 to 55 when each of the magnetic sensors S1 to S5 detects the magnetic scale on the opposite side of the center of the magnetic scale C1 to the movement direction of the mover C1 (the left side in FIG. 3) is set to positive, and the count value of each of the counting units 51 to 55 when each of the magnetic sensors S1 to S5 detects the magnetic scale on the side of the center of the magnetic scale C1 in the movement direction of the mover C1 (the right side in FIG. 3) is set to negative.

[0031] In the illustrated example, the position of the reference mark Z1 corresponds to the count value "0," the first switch position SW1 corresponds to, for example, the count value "+15,000," and the second switch position SW2 corresponds to, for example, the count value "-15,000." Hereinafter, the count value "+15,000" at the first switch position SW1 is also referred to as the switch count value, and the count value "-15,000" at the second switch position SW2 is also referred to as the start count value. In the illustrated example, the switch count value and the start count value differ only in their positive and negative signs. In the illustrated state, when the first switch position SW1 of the magnetic scale C1 comes over the magnetic sensor S1, the switch count value "+15,000" of the counting unit 51 is converted to the start count value "-15,000" of the counting unit 52 of the magnetic sensor S2 at the second switch position SW2. Thereafter, magnetic sensor S2 takes the lead in determining the position of magnetic scale C1, and its counting section 52 counts from the initial count value "-15,000" to the next switching count value (for magnetic sensor S3) of "+15,000."

[0032] The reference mark detection control unit 40 in Figure 2 includes a reference mark detection enabling unit 41 that enables the detection of the reference mark Z1 by each of the magnetic sensors S1 to S5 in accordance with the count values ​​in each of the counting units 51 to 55, and a reference mark detection disabling unit 42 that disables the detection of the reference mark Z1 by each of the magnetic sensors S1 to S5 in accordance with the count values ​​in each of the counting units 51 to 55.

[0033] Before describing the control of the detection of the reference mark Z1 by the reference mark detection enabling unit 41 and / or the reference mark detection disabling unit 42, other embodiments are shown in FIGS. 4 and 5. As shown in FIG. 4, when the mover C1 is used for the first time in the linear conveyance system 1, the reference mark Z1 on the magnetic scale C1 must be detected by one of multiple magnetic sensors (S1 and S2 in the example of FIG. 4) to identify or register the reference position or initial position of the mover C1. Each of the magnetic sensors S1 and S2 must be able to reliably detect the reference mark Z1 and identify that the reference mark Z1 belongs to the mover C1. Therefore, to prevent erroneous detection of the reference mark Z1 and / or the mover C1, the magnetic sensors S1 and S2 are generally in a state where they cannot detect the reference mark Z1, and detection of the reference mark Z1 is enabled only when they can reliably detect the reference mark Z1 and the mover C1.

[0034] As shown in Fig. 4, a mover C1, whose initial position is not registered in the linear conveyance system 1, moves along the rail from the left to the right of the magnetic sensor S1. The position of the magnetic scale C1 in the state shown in Fig. 4 is not above either of the magnetic sensors S1 or S2, and is shown as "S1 left" in Fig. 5. In this "S1 left" state, neither of the magnetic sensors S1 nor S2 detects the magnetic graduations of the A / B phases of the magnetic scale C1, so "S1-A / B phase" and "S2-A / B phase" in Fig. 5, which schematically show the count values ​​of the respective counting units 51 and 52 (Fig. 2), are both "0".

[0035] When the mover C1 moves from the state shown in FIG. 4 and at least the right end E1R of the magnetic scale C1 comes over the magnetic sensor S1, the magnetic sensor S1 detects the A / B phase magnetic scale formed on the right end E1R and / or the scale main body AB1, and the count value in the counter 51 increases according to the number of A / B phase pulses from the magnetic sensor S1. In the example shown in FIG. 5, when the "scale position" of the magnetic scale C1 switches from "S1 left" to "S1 up," "S1-A / B phase," which represents the count value in the counter 51, increases from "1" to "12." In this "S1 up" state, the magnetic scale C1 is not over the magnetic sensor S2, and the magnetic sensor S2 does not detect the A / B phase magnetic scale of the magnetic scale C1, so "S2-A / B phase," which represents the count value in the counter 52, remains "0." In this embodiment, for the sake of simplicity, the count value "18" represents the total length of one magnetic scale, but the count value per magnetic scale in an actual linear conveying system 1 is very large, for example, approximately "30,000" ("-15,000" to "+15,000") as described above with reference to Figure 3.

[0036] When the count value of "S1-A / B phase" in Figure 5 reaches "9," the "Z" that appears in the "S1-Z phase" column means that the reference mark Z1 is located above the magnetic sensor S1. However, as mentioned above, the magnetic sensor S1 is in a state where it cannot detect the reference mark Z1 in principle ("S1-Z detection" is set to "Not possible"), so it does not detect the reference mark Z1 when the count value of "S1-A / B phase" reaches "9."

[0037] 5, when the count value of "S1-A / B phase" is between "13" and "18," the magnetic scale C1 is in an "S1&S2 above" state, where it is above both 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 and the portion to the left of the scale main body AB1) is above the magnetic sensor S1, and the portion of the magnetic scale C1 to the right of the reference mark Z1 (the right end E1R and the portion to the right of the scale main body AB1) is above the magnetic sensor S2. In this "S1&S2 above" state, both magnetic sensors S1 and S2 detect the magnetic graduations of the A / B phases of the magnetic scale C1, and therefore "S1-A / B phase" and "S2-A / B phase," which represent the count values ​​of the respective counters 51 and 52, both increase in the same manner.

[0038] In this embodiment, when the "S1-A / B phase" and "S2-A / B phase" continuously increase or decrease by a predetermined count value (a count value of "3" in the illustrated example) at approximately the same time in the same direction, detection of the reference mark Z1 by the magnetic sensor in the direction of increase or decrease, i.e., the moving direction of the mover C1, is validated. In the illustrated example, the increase in the "S1-A / B phase" from "13" to "15" and the increase in the "S2-A / B phase" from "1" to "3" occur continuously at approximately the same time by a count value of "3," so detection of the reference mark Z1 by the magnetic sensor S2 in the direction of increase, i.e., the moving direction from left to right of the mover C1 (i.e., the right side) is validated. In this way, when the count value of the "S2-A / B phase" reaches "4" or later, "S2-Z detection" switches from "not possible" to "possible."

[0039] In this state, when the count value of "S2-A / B phase" reaches "9," the reference mark Z1 comes above 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 conveyance system 1. Note that when the count value of "S2-A / B phase" reaches "9," the magnetic scale C1 passes the magnetic sensor S1 to the right, so the "scale position" is "above S2," which means that the magnetic scale C1 is above (only) the magnetic sensor S2, and the count value of "S1-A / B phase" remains constant at the maximum value of "18."

[0040] As described above, in the embodiment shown in Figures 4 and 5, detection of the reference mark Z1 by the magnetic sensor S2 located in the direction of movement of the mover C1 is validated only when the count values ​​of the two adjacent magnetic sensors S1 and S2 continuously change by a predetermined count value at approximately the same time in the same direction. Therefore, the reference mark Z1 of the mover C1 simultaneously detected by both magnetic sensors S1 and S2 can be reliably detected by the magnetic sensor S2 at the destination. However, when two movers close to each other move at a constant speed, the count values ​​of the two adjacent magnetic sensors that individually detect each mover may continuously change by a predetermined count value at approximately the same time in the same direction. This leaves the possibility of erroneous detection of the reference mark and / or the mover. According to the embodiment described below, the configuration shown in Figure 2 (particularly, the fiducial mark detection validation unit 41 and / or the fiducial mark detection invalidation unit 42) further reduces the possibility of erroneous detection of the reference mark and / or the mover.

[0041] In Figure 2, based on the counting values ​​of each counting unit 51 to 55, when the magnetic scales C1 and C2 move from a state in which they straddle the detection ranges of two adjacent magnetic sensors S1 / S2, S2 / S3, S3 / S4, and S4 / S5 to outside the detection range of one of the magnetic sensors S1 to S5, 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.

[0042] In the simple embodiment shown in Figures 6 and 7, the reference mark detection enablement unit 41, based on the counting values ​​in the counting units 51, 52 (not shown in Figure 6), enables detection of the reference mark Z1 by the other magnetic sensor S2 on the movement direction side of the movable element C1 when the magnetic scale C1 moves from a state in which it straddles the detection ranges of two adjacent magnetic sensors S1 / S2 to outside the detection range of one of the magnetic sensors S1 as shown by the dashed line.

[0043] As shown in FIG. 7, the reference mark detection validation unit 41 determines that the magnetic scale C1 straddles two adjacent detection ranges in an "over S1&S2" state when the counts of the counters 51, 52 of the two adjacent magnetic sensors S1, S2 change in the same manner, as in FIG. 5 (in the illustrated example, the count of the magnetic sensor S1 increases from "13" to "15" while the count of the magnetic sensor S2 increases from "1" to "3"). In this "over S1&S2" state, the magnetic scale C1 is located above both magnetic sensors S1 and S2, as shown by the solid lines in FIG. 6. The reference mark Z1 at this time is located between the detection ranges of the two adjacent magnetic sensors S1 and S2.

[0044] As shown in FIG. 7, the "S1 & S2 on" state, in which the magnetic scale C1 straddles two adjacent detection ranges, continues until the count value of magnetic sensor S1 reaches "18" and the count value of magnetic sensor S2 reaches "6." When the count value of magnetic sensor S2 alone increases to "7" while the count value of magnetic sensor S1 remains at "18," the mover C1 moves out of the detection range of the one magnetic sensor S1 on the opposite side of the movement direction, as indicated by the dashed line in FIG. 6, and the state changes to "S2 on." Therefore, the reference mark detection enablement unit 41 enables detection of the reference mark Z1 by the other magnetic sensor S2 on the movement direction side of the mover C1 when the count value of only magnetic sensor S2 increases to "7." The reference mark detection enablement unit 41 may also enable detection of the reference mark Z1 by the other magnetic sensor S2 on the movement direction side of the mover C1 when the magnetic sensor S1 can no longer detect the A / B phase magnetic graduations of the magnetic scale C1.

[0045] At this point, the reference mark Z1 is still sandwiched between the detection ranges of the two adjacent magnetic sensors S1 and S2, as shown by the dashed lines in Fig. 6, so as the mover C1 continues to move in the same direction, the reference mark Z1 will come above the magnetic sensor S2. Specifically, when the count value of the magnetic sensor S2 becomes "9," the reference mark Z1 will come above the magnetic sensor S2 ("Z" will appear in the "S2-Z phase" column), and the reference mark Z1 will be detected by the magnetic sensor S2, and the initial position of the mover C1 will be registered in the linear conveyance system 1. When the other magnetic sensor S2 on the movement direction side, which was enabled by the reference mark detection enabling unit 41 at an S2 count value of "7," detects the reference mark Z1 at an S2 count value of "9," the reference mark detection disabling unit 42 in Fig. 2 disables the detection of the reference mark Z1 by the other magnetic sensor S2 at an S2 count value of "10" or later (sets "S2-Z detection" to "disabled").

[0046] Next, we will explain the case where there are multiple movers. In this case, two movers (i.e., magnetic scales) that are close to each other may simultaneously enter the detection range of one magnetic sensor, so it is preferable to take measures in advance to prevent erroneous detection of each magnetic scale, as shown in Figure 8.

[0047] FIG. 8 shows a schematic diagram of two magnetic scales C1 and C2 approaching each other to the minimum distance, simultaneously entering the detection range R of one magnetic sensor S1-S5. In this example, the minimum approach distance between the two magnetic scales C1 and C2 (the distance between the right end of magnetic scale C1 and the left end of magnetic scale C2 in the illustrated state) is 2 mm, and the length of the detection range R of the magnetic sensors S1-S5 in the orbital direction (the horizontal direction in FIG. 8) 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 graduations formed thereon, similar to the scale body AB1 of the magnetic scale C1 and the scale body AB2 of the magnetic scale C2. Therefore, in the illustrated state, the magnetic sensors S1-S5 simultaneously detect the A / B-phase magnetic graduation at the right end E1R and the A / B-phase magnetic graduation at the left end E2L. In this case, the magnetic sensors S1-S5 cannot distinguish between the two magnetic scales C1 and C2.

[0048] In order to prevent erroneous detection of two magnetic scales C1 and C2 that are so close to each other, shielding members B1R and / or B2L are provided to shield the right end E1R of magnetic scale C1 and / or the left end E2L of magnetic scale C2 from the detection range R of magnetic sensors S1 to S5.

[0049] The shielding member B1R shields at least the A / B phase magnetic scales provided on the right end portion E1R of the magnetic scale C1, farthest from the scale main body AB1, on the right end side. Specifically, as described above, the right end portion of the right end portion E1R, which has 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 equal to or greater than the length (5 mm) of the detection range R of the magnetic sensors S1 to S5 in the track direction, the shielding member B1R alone can shield the detection range R of the magnetic sensors S1 to S5, preventing the magnetic scale C1 from being detected simultaneously with the magnetic scale C2. Furthermore, if the length of the shielding member B1R in the track direction is set to be at least 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 alone will substantially shield the detection range R of the magnetic sensors S1 to S5, preventing the magnetic scale C1 from being detected simultaneously with the magnetic scale C2. 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 (5 mm) of the detection range R of the magnetic sensors S1 to S5 minus the minimum approachable distance (2 mm) of the movers C1 and C2, the shielding member B1R, together with the shielding member B2L of the same length, will substantially shield the detection range R of the magnetic sensors S1 to S5, preventing the magnetic scale C1 from being detected simultaneously with the magnetic scale C2.

[0050] The shielding member B2L shields at least the A / B phase magnetic scales provided on the left end side, farthest from the scale main body AB2, of the left end E2L of the magnetic scale C2. Specifically, as described above, the left end portion of the left end E2L, which has 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 equal to or greater than the length (5 mm) of the detection range R of the magnetic sensors S1 to S5 in the track direction, the shielding member B2L alone can shield the detection range R of the magnetic sensors S1 to S5, preventing the magnetic scale C2 from being detected simultaneously with the magnetic scale C1. Furthermore, if the length of the shielding member B2L in the track direction is set to at least the length (3 mm) obtained by subtracting the minimum approach 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 B2L alone will substantially shield the detection range R of the magnetic sensors S1 to S5, preventing the magnetic scale C2 from being detected simultaneously with the magnetic scale C1. Furthermore, if the length of the shielding member B2L in the track direction is set to at least half (1.5 mm) of the length (5 mm) of the detection range R of the magnetic sensors S1 to S5 in the track direction minus the minimum approach distance (2 mm) of the movers C1 and C2, the shielding member B2L, together with the shielding member B1R of the same length, will substantially shield the detection range R of the magnetic sensors S1 to S5, preventing the magnetic scale C2 from being detected simultaneously with the magnetic scale C1.

[0051] 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 a 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 a shielding member may be provided only at the right end.

[0052] The shielding member B1R and / or the shielding member B2L is 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 and alloys such as iron, cobalt, nickel, gadolinium, and manganese. If an optical scale is used as the positioning scale instead of a magnetic scale, the shielding member may be formed of a light-shielding material that optically shields the optical sensor serving as the position detection unit. As described above, by taking the measures shown in FIG. 8, even if the ends of the positioning scales of two movers that are close to each other simultaneously enter the detection range of one position detection unit, the shielding member provided on at least one of the ends can prevent the two positioning scales from being erroneously detected simultaneously by the position detection unit.

[0053] Next, we will explain several examples in which two moving elements close to each other move at a constant speed, which could result in erroneous detection of the reference mark and / or moving element in the examples of Figures 4 and 5 (examples that do not use the reference mark detection enabling unit 41 and / or the reference mark detection disabling unit 42).

[0054] 9 and 10, in the initial state shown in Fig. 9 (a state in which movers C1 and C2, whose initial positions are not registered, start moving to the right), mover C1 is above both magnetic sensors S2 and S3, and mover C2 is above magnetic sensor S4. As shown in Fig. 10, based on the count values ​​of counters 52 and 53, when magnetic scale C1 moves from a state in which it straddles the detection ranges of two adjacent magnetic sensors S2 / S3 to a state in which it moves out of the detection range of one magnetic sensor S2, reference mark detection validation unit 41 validates detection of reference mark Z1 by the other magnetic sensor S3 on the side in the movement direction of mover C1.

[0055] In this state, when the mover C1 moves further in the same direction, the reference mark Z1 comes above the magnetic sensor S3, so that the reference mark Z1 is detected by the magnetic sensor S3 and the initial position of the mover C1 is registered in the linear conveyance 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. Note that thereafter, a situation occurs in which the magnetic scale C1 moves from a state in which it straddles the detection ranges of the two adjacent magnetic sensors S3 / S4 to outside the detection range of one of the magnetic sensors S3, but because the reference mark Z1 of the magnetic scale C1 has already been detected by the magnetic sensor S3, the detection of the reference mark Z1 by the magnetic sensor S4 is not valid.

[0056] On the other hand, when the magnetic scale C2 moves from a state in which it straddles the detection ranges of two adjacent magnetic sensors S4 / S5 to an out-of-range state of one of the magnetic sensors S4, 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 ​​of the counters 54 and 55. If the mover C2 continues to move in the same direction under this condition, the reference mark Z2 will be located above the magnetic sensor S5, which will detect the reference mark Z2 and register the initial position of the mover C2 in the linear conveyance 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 that are close to each other move at a constant speed, the reference marks Z1 and Z2 of each mover C1 and C2 can be reliably detected.

[0057] 11 and 12, in the initial state shown in Fig. 11, the mover C1 is located above the magnetic sensor S2, and the mover C2 is located above both the magnetic sensors S3 and S4. As shown in Fig. 12, when the magnetic scale C2 moves from a state in which it straddles the detection ranges of two adjacent magnetic sensors S3 / S4 to a state in which it moves out of the detection range of one of the magnetic sensors S3, the reference mark detection validation unit 41 validates the detection of the reference mark Z2 by the other magnetic sensor S4 on the side in the movement direction of the mover C2, based on the count values ​​of the counting units 53 and 54.

[0058] If the mover C2 moves further in the same direction in this state, the reference mark Z2 will come above the magnetic sensor S4, so that the reference mark Z2 is detected by the magnetic sensor S4 and the initial position of the mover C2 is registered in the linear conveyance 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. Note that thereafter, a situation occurs in which the magnetic scale C2 moves from a state in which it straddles the detection ranges of the two adjacent magnetic sensors S4 / S5 to outside the detection range of one of the magnetic sensors S4, but because the reference mark Z2 of the magnetic scale C2 has already been detected by the magnetic sensor S4, the detection of the reference mark Z2 by the magnetic sensor S5 is not valid.

[0059] On the other hand, when the magnetic scale C1 moves from a state in which it straddles the detection ranges of two adjacent magnetic sensors S2 / S3 to an out-of-range state of one of the magnetic sensors S2, the reference mark detection validating 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 ​​of the counters 52 and 53. If the mover C1 continues to move in the same direction under this condition, the reference mark Z1 will be located above the magnetic sensor S3, which will detect the reference mark Z1 and register the initial position of the mover C1 in the linear conveyance system 1. After the reference mark Z1 is detected by the magnetic sensor S3, the reference mark detection invalidating 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 that are close to each other move at a uniform speed, the reference marks Z1 and Z2 of each mover C1 and C2 can be reliably detected.

[0060] 13 and 14, in the initial state shown in Fig. 13, the mover C1 is located above both magnetic sensors S1 and S2, and the mover C2 is located above both magnetic sensors S3 and S4. As shown in Fig. 14, when the magnetic scale C1 moves from a state in which it straddles the detection ranges of two adjacent magnetic sensors S1 / S2 to a state in which it moves out of the detection range of one magnetic sensor S1, the reference mark detection validation unit 41 validates the detection of the reference mark Z1 by the other magnetic sensor S2 on the side in the movement direction of the mover C1, based on the count values ​​of the counting units 51 and 52.

[0061] In this state, if the mover C1 moves further in the same direction, the reference mark Z1 will come above the magnetic sensor S2, so that the reference mark Z1 is detected by the magnetic sensor S2 and the initial position of the mover C1 is registered in the linear conveyance 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. Note that thereafter, a situation occurs in which the magnetic scale C1 moves from a state in which it straddles the detection ranges of the two adjacent magnetic sensors S2 / S3 to a state in which it moves out of the detection range of one of the magnetic sensors S2, but because the reference mark Z1 of the magnetic scale C1 has already been detected by the magnetic sensor S2, the detection of the reference mark Z1 by the magnetic sensor S3 is not valid.

[0062] On the other hand, based on the counting values ​​in the counting units 53 and 54, when the magnetic scale C2 moves from a state in which it straddles the detection ranges of two adjacent magnetic sensors S3 / S4 to outside the detection range of one of the magnetic sensors S3, the reference mark detection validation unit 41 validates the detection of the reference mark Z2 by the other magnetic sensor S4 on the side of the movement direction of the movable element C2.

[0063] If the mover C2 continues to move in the same direction in this state, the reference mark Z2 will come above the magnetic sensor S4, which will detect the reference mark Z2 and register the initial position of the mover C2 in the linear conveyance system 1. After the magnetic sensor S4 detects the reference mark Z2, the reference mark detection invalidation unit 42 invalidates the detection of the reference mark Z2 by the magnetic sensor S4. Although not shown, there may be a case where the magnetic scale C2 moves from a state in which it straddles the detection ranges of the two adjacent magnetic sensors S4 / S5 to an outside of the detection range of one of the magnetic sensors S4. However, because the reference mark Z2 of the magnetic scale C2 has already been detected by the magnetic sensor S4, the detection of the reference mark Z2 by the magnetic sensor S5 is not valid. As described above, even when the two movers C1 and C2 that are close to each other move at a uniform speed, the reference marks Z1 and Z2 of each mover C1 and C2 can be reliably detected.

[0064] In the first to third embodiments described above, the movement direction of each of the movers C1, C2 was constant, but even if the movement direction of each of the movers C1, C2 changes, the reference marks Z1, Z2 of each of the movers C1, C2 can be reliably detected. For example, after the other magnetic sensor (for example, the right side) is enabled by the reference mark detection enablement unit 41, if the magnetic scales C1, C2 return to a state in which they straddle the detection ranges of one magnetic sensor (for example, the left side) and the other magnetic sensor before the other magnetic sensor detects the reference marks Z1, Z2, and then move out of the detection range of the other magnetic sensor, the reference mark detection enablement unit 41 enables the detection of the reference marks Z1, Z2 by one of the magnetic sensors.

[0065] In this case, the reference mark detection disabling unit 42 may disable detection of the reference marks Z1 and Z2 by the other magnetic sensor if, after the other magnetic sensor is enabled by the reference mark detection enabling unit 41, the magnetic scales C1 and C2 return to a state in which they straddle the detection ranges of one magnetic sensor and the other magnetic sensor before the other magnetic sensor detects the reference marks Z1 and Z2, and then move out of the detection range of the other magnetic sensor. Alternatively, the reference mark detection disabling unit 42 may disable detection of the reference marks Z1 and Z2 by the other magnetic sensor if, after the other magnetic sensor is enabled by the reference mark detection enabling unit 41, the magnetic scales C1 and C2 return to a state in which they straddle the detection ranges of the one magnetic sensor and the other magnetic sensor before the other magnetic sensor detects the reference marks Z1 and Z2.

[0066] The present invention has been described above based on the embodiments. The embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in the combination of the respective components and treatment processes, and that such modifications are also within the scope of the present invention.

[0067] In the embodiment, a linear conveying system is illustrated in which a mover is driven based on the magnetic force between a permanent magnet provided on the mover and an electromagnet provided on the stator, but the present invention can be applied to any driving device based on any principle other than magnetism (for example, electricity or fluid).

[0068] The functional configuration of each device described in the embodiments can be realized by hardware resources, software resources, or a combination of hardware and software resources. Examples of hardware resources include processors, ROMs, RAMs, and other LSIs. Examples of software resources include operating systems, applications, and other programs. [Explanation of symbols]

[0069] 1 Linear transport system, 2 Stator, 3 Movable element, 4 Positioning device, 40 Reference mark detection control unit, 41 Reference mark detection enabling unit, 42 Reference mark detection disabling unit, 51 Counting unit, AB1 Scale body, B1R Shielding member, C1 Magnetic scale, S1 Magnetic sensor, Z1 Reference mark.

Claims

1. A positioning scale attached to a mover and positioned by a position detection unit disposed on the track of the mover, A positioning scale comprising a shielding member that shields the scale at at least one end from the detection range of the position detection unit.

2. The positioning scale according to claim 1 , wherein the shielding members are provided at both ends of the positioning scale.

3. A positioning scale as described in claim 1 or 2, wherein the length in the orbital direction of the movable element of the shielding member that shields the scale from the detection range of the position detection unit is greater than or equal to the length in the orbital direction of the detection range of the position detection unit.

4. A positioning scale as described in claim 1 or 2, wherein the length of the movable element in the orbital direction of the shielding member that shields the scale from the detection range of the position detection unit is equal to or greater than the length of the detection range of the position detection unit in the orbital direction minus the minimum approachable distance of the multiple movable elements, or is equal to or greater than half the length of the detection range of the position detection unit in the orbital direction minus the minimum approachable distance of the multiple movable elements.

5. The positioning scale is a magnetic scale, the scale is a magnetic scale whose position is magnetically measured by the position detection unit; A positioning scale according to any one of claims 1 to 4.

6. the position detection unit is a magnetic sensor, the shielding member is formed of a ferromagnetic material that magnetically shields the at least one end from a detection range of the magnetic sensor.

6. The positioning scale according to claim 5.

7. a plurality of the position detection units are arranged along the orbital direction of the mover, the positioning scale includes a scale body having a length in the track direction greater than an interval between the plurality of position detection units, and two end portions sandwiching both ends of the scale body in the track direction from both sides, the shielding member shields at least one of the two end portions, the end farther from the scale body, from the detection range of the position detection unit; A positioning scale according to any one of claims 1 to 6.

8. a plurality of scales to be detected by the position detection unit are provided on the scale body and both end portions along the track direction; the shielding member shields the scale provided on the end side of at least one of the two end portions from a detection range of the position detection unit; 8. The positioning scale according to claim 7.

9. A movable element to which a positioning scale is attached, the position of which is measured by a position detection unit arranged on the orbit of the movable element, the positioning scale having a shielding member that shields the scale at at least one end from the detection range of the position detection unit.

10. a plurality of movers driven along a track; a position detection unit disposed on the track and configured to detect positions of the plurality of movers; a plurality of positioning scales attached to the plurality of movers and whose positions are measured by the position detection unit, the plurality of positioning scales including a shielding member that shields the scale at at least one end from a detection range of the position detection unit; A drive unit comprising:

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