Positioning device, driving device, positioning method, positioning program

Abstract

To provide a positioning device and the like which can surely detect a reference mark provided in a movable element.SOLUTION: A positioning device 4 includes: a plurality of magnetic sensors S1-S5 which are arranged along the movement direction of a movable element for positioning magnetic scales C1, C2 attached to the movable element, have an interval thereof smaller than the length in the movement direction of the magnetic scales C1, C2 and specify a reference position of the movable element by detecting reference marks Z1, Z2 provided in the movable element; and a reference mark detection validation unit 41 which validates detection of the reference marks Z1, Z2 with the other magnetic sensor when moving to the outside of a detection range of one magnetic sensor from a state where the magnetic scales C1, C2 straddle the detection range of the two adjacent magnetic sensors S1 / S2, S2 / S3, S3 / S4, S4 / S5.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a driving device that moves a mover along an orbit and the like.

Background Art

[0002] Patent Document 1 discloses a linear conveyance system as a driving device that moves a mover along an orbit. A plurality of magnetic sensors arranged along the orbit position a magnetic scale (i.e., the mover) attached to the mover. The magnetic sensors can identify the reference position of the mover by detecting a reference mark provided on the mover.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the linear conveyance system of Patent Document 1, the interval between a plurality of magnetic sensors is smaller than the length of the magnetic scale in the orbital direction. For this reason, one magnetic scale (i.e., the mover) may straddle the detection ranges of two adjacent magnetic sensors. Further, when there are a plurality of movers, two different magnetic scales (i.e., movers) may simultaneously enter the detection ranges of two adjacent magnetic sensors. Even in such a complicated case, the magnetic sensors must surely detect each reference mark and identify the mover provided with each reference mark.

[0005] The present invention has been made in view of such circumstances, and an object thereof is to provide a positioning device or the like that can surely detect a reference mark provided on a mover.

Means for Solving the Problems

[0006] In order to solve the above problems, a positioning device according to an aspect of the present invention includes a plurality of position detection units arranged along the moving direction of a mover for positioning a positioning scale attached to the mover, the interval between the plurality of position detection units being smaller than the length of the positioning scale in the moving direction, and a plurality of position detection units for specifying a reference position of the mover by detecting a reference mark provided on the mover, and a reference mark detection enabling unit for enabling the detection of the reference mark by the other position detection unit when the positioning scale moves out of the detection range of one position detection unit from a state where the positioning scale straddles the detection ranges of two adjacent position detection units.

[0007] In this aspect, when the positioning scale moves out of the detection range of one position detection unit from a state where the positioning scale straddles the detection ranges of two adjacent position detection units, the detection of the reference mark by the other position detection unit is enabled. For example, when there are a plurality of movers (i.e., positioning scales), even if two different positioning scales enter the detection ranges of two adjacent position detection units at the same time, the detection of the reference mark is not enabled in that state, so that false detection of the reference mark can be prevented.

[0008] Another aspect of the present invention is a driving device. This device includes a plurality of movers driven along a track, and a plurality of position detection units arranged along the track for positioning a positioning scale attached to each mover, the interval between the plurality of position detection units being smaller than the length of the positioning scale in the track direction, and a plurality of position detection units for specifying a reference position of each mover by detecting a reference mark provided on each mover, and a reference mark detection enabling unit for enabling the detection of the reference mark by the other position detection unit when the positioning scale moves out of the detection range of one position detection unit from a state where the positioning scale straddles the detection ranges of two adjacent position detection units.

[0009] Still another aspect of the present invention is a positioning method. This method is a plurality of position detection units arranged along the moving direction of a mover for positioning a positioning scale attached to the mover, the interval between which is smaller than the length of the moving direction of the positioning scale, and includes a plurality of position detection units for specifying the reference position of the mover by detecting a reference mark provided on the mover. In a positioning device, when the positioning scale moves out of the detection range of one position detection unit from a state where it straddles the detection ranges of two adjacent position detection units, it includes a reference mark detection enabling step of enabling the detection of the reference mark by the other position detection unit.

[0010] In addition, any combination of the above components, or those obtained by converting these expressions into methods, devices, systems, recording media, computer programs, etc., are also included in the present invention.

Advantages of the Invention

[0011] According to the present invention, the reference mark provided on the mover can be reliably detected.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

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Best Mode for Carrying Out the Invention

[0013] Hereinafter, embodiments for carrying out the present invention (hereinafter also referred to as embodiments) will be described in detail with reference to the drawings. In the description and / or the drawings, the same or equivalent components, members, processes, etc. are denoted by the same reference numerals, and duplicate descriptions are omitted. The scales and shapes of the respective parts shown are set for the sake of simplicity of explanation and are not to be construed restrictively unless otherwise specified. The embodiments are illustrative and do not limit the scope of the present invention in any way. All features described in the embodiments and combinations thereof 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 an aspect of a drive device according to the present invention. The linear conveyance system 1 includes a stator 2 that constitutes an annular rail or track, and a plurality of movers 3A, 3B, 3C, 3D (hereinafter collectively referred to as mover 3) that are driven with respect to the stator 2 and are movable along the rail. An electromagnet or coil provided on the stator 2 and a permanent magnet provided on the mover 3 face each other, thereby forming a linear motor along the annular rail. Note that the rail formed by the stator 2 may have any shape and is not limited to an annular shape. For example, the rail may be linear, curved, one rail may branch into a plurality of rails, or a plurality of rails may merge into one rail. Also, the installation direction of the rail formed by the stator 2 is arbitrary. In the example of FIG. 1, the rail is disposed in a horizontal plane, but the rail may be disposed in a vertical plane or in a plane or a curved surface at an arbitrary 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 shape along the formation direction of the rail, and when forming an annular rail as in the example of FIG. 1, it becomes an endless strip shape with (virtually) both ends connected. A plurality of drive modules (not shown) including electromagnets are continuously or periodically embedded or arranged along the rail on the rail surface 21 capable of forming a rail of any shape in this way. The electromagnets in the drive modules generate a magnetic field that exerts a propulsive force along the rail on the permanent magnet and / or the electromagnet itself of the mover 3. Specifically, when a drive current such as three-phase alternating current is passed through these numerous electromagnets, a moving magnetic field is generated that linearly drives the mover 3 provided with a permanent magnet in a desired tangential direction along the rail. In the example of FIG. 1, 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 may be the vertical direction or any other arbitrary direction.

[0016] In the stator 2, on the upper surface or the lower surface perpendicular to the rail surface 21, a plurality of magnetic sensors (not shown in FIG. 1), which are position detection units capable of measuring the position of a magnetic scale (not shown in FIG. 1) serving as a positioning target or a positioning scale attached to the mover 3, are continuously or periodically embedded. A magnetic sensor that measures a magnetic scale formed by a striped magnetic pattern or magnetic graduations with a constant pitch generally includes a plurality of magnetic detection heads. By shifting the intervals between the plurality of 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 accuracy. In a typical magnetic sensor provided with two magnetic detection heads, for example, the interval between the two magnetic detection heads is shifted by 1 / 4 pitch (the phase is shifted by 90 degrees) with respect to the magnetic pattern of the magnetic scale. Incidentally, conversely, a magnetic sensor may be provided on the mover 3 and a magnetic scale may be provided on the stator 2. Also, if the position of the mover 3 measured by the positioning unit 22 is differentiated with respect to time, the speed of the mover 3 can be detected, and if the speed is differentiated with respect to time, the acceleration of the mover 3 can be detected.

[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 above magnetic type, and may be an optical type or other types. In the case of the optical type, an optical scale formed by a striped pattern or graduations with a constant pitch is attached to the mover 3, and an optical sensor capable of optically reading the striped pattern of the optical scale is provided on the stator 2. In the magnetic type and the optical type, since the position detection unit measures the positioning target (magnetic scale or optical scale) in a non-contact manner, the risk of failure of the position detection unit, etc. when the object to be conveyed carried by the mover 3 scatters and enters the positioning location (the upper surface of the stator 2) can be reduced. However, in the case of the optical type, if the optical scale is covered by the object to be conveyed such as liquid or powder that has entered the positioning location, the positioning accuracy deteriorates. Therefore, if the object to be conveyed has negligible magnetism, it is preferable to use the magnetic type that does not deteriorate the positioning accuracy even if it enters the positioning location.

[0018] The mover 3 includes a mover body 31 facing the rail surface 21 of the stator 2, a measured part 32 projecting horizontally from the upper part of the mover body 31 and facing the positioning part 22 of the stator 2, and a conveying part 33 projecting horizontally from the mover body 31 on the side opposite to the measured part 32 (the side far from the stator 2) where the object to be conveyed is placed or fixed. The mover body 31 includes one or a plurality of permanent magnets (not shown) facing a plurality of electromagnets embedded in the rail surface 21 of the stator 2 along the rail. Since the moving magnetic field generated by the electromagnets of the stator 2 applies a linear driving force or a propulsive force in the tangential direction of the rail to the permanent magnets and / or the electromagnets themselves of the mover 3, the mover 3 is linearly driven along the rail surface 21 with respect to the stator 2.

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

[0020] In Fig. 1, four movers 3A, 3B, 3C, and 3D are illustrated. However, in the linear conveyance system 1 that conveys a large number of small conveyed objects, for example, it is also assumed that a number of movers 3 exceeding 1,000 may be required. In such a case, a situation frequently occurs where two different positioning scales (i.e., movers 3) simultaneously enter the detection ranges of two adjacent position detection units. Also, there is a possibility 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 a complex situation, each position detection unit must surely detect the reference marks of the mover 3 described below and must be able to uniquely identify the mover 3 provided with each of the reference marks.

[0021] Fig. 2 schematically shows a positioning device 4 composed of a position detection unit and a positioning scale in the linear conveyance system 1. The positioning device 4 includes a plurality (two in the illustrated example) of magnetic sensors S1 to S5 as position detection units embedded or arranged on the rail surface 21 along the orbital direction of the stator 2 or the moving direction (the left - right direction in Fig. 2) of the movers C1 and C2 in order to position magnetic scales (hereinafter also referred to as magnetic scales C1 and C2 for convenience) attached to the plurality (two in the illustrated example) of movers C1 and C2.

[0022] The intervals in the moving direction of each of the magnetic sensors S1 to S5 may be different from each other, but in this embodiment, an example where all the intervals are equal will be described. In this case, the interval in the moving direction of each of the magnetic sensors S1 to S5 is, for example, 30 mm. Also, the lengths in the moving direction of each of the magnetic scales C1 and C2 may be different from each other, but in this embodiment, an example where all the lengths are equal will be described. In this case, the length in the moving direction of each of the magnetic scales C1 and C2 is, for example, 48 mm. Thus, in this embodiment, the interval (30 mm) in the moving direction of each of the magnetic sensors S1 to S5 is smaller than the length (48 mm) in the moving direction of each of the magnetic scales C1 and C2.

[0023] The magnetic scale C1 has both end portions E1L and E1R in the moving direction, and a long scale body AB1 sandwiched between the both end portions E1L and E1R from both sides in the moving direction. A number of magnetic graduations or magnetic patterns are formed on the scale body AB1 at equal intervals along the moving direction. Each of the magnetic sensors S1 to S5 that detects the magnetic graduations on the scale body AB1 outputs general A-phase and B-phase pulses in a known linear encoder. Typically, the phases of the A-phase pulse and the B-phase pulse are different from each other by 90 degrees. Note that magnetic graduations similar to those of the scale body AB1 may also be formed at both end portions E1L and E1R of the magnetic scale C1.

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

[0025] A reference mark Z1 as a reference mark is provided on the mover C1 and / or the magnetic scale C1. Each of the magnetic sensors S1 to S5 that magnetically detects the reference mark Z1 outputs a general Z-phase pulse in a known linear encoder. Although details will be described later, the Z-phase pulse output according to the reference mark Z1 is used to specify 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 the scale body AB1 in the moving direction. Each distance (24 mm) between the reference mark Z1 and both ends of the magnetic scale C1 in the moving direction is smaller than the interval (30 mm) of the plurality of magnetic sensors S1 to S5. Also, each distance (16 mm) between the reference mark Z1 and both ends of the scale body AB1 in the moving direction is smaller than the interval (30 mm) of the plurality of magnetic sensors S1 to S5.

[0026] The description of the above magnetic scale C1 also applies to other magnetic scales such as magnetic scale C2. However, the dimensions of each part and the positions of the reference marks above can be arbitrarily determined for each magnetic scale. Unless otherwise specifically mentioned below, the description of magnetic scale C1 also applies to magnetic scale C2 etc. in the same way, and duplicate descriptions of magnetic scale C2 etc. will be omitted.

[0027] Each of the magnetic sensors S1 to S5 includes counting units 51 to 55 that count the A / B-phase magnetic scales 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 of the count value in each of the counting units 51 to 55 corresponds to the moving direction 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 the left side to the right side in FIG. 2, the count values in each of the counting units 51 to 55 increase according to the number of A / B-phase pulses output by each of the magnetic sensors S1 to S5. When the mover C1 moves from the right side to the left side in FIG. 2, the count values in each of the counting units 51 to 55 decrease according to the number of A / B-phase pulses output by each of the magnetic sensors S1 to S5.

[0028] When the mover C1 moves on the rail, the magnetic sensors S1 to S5 for positioning the magnetic scale C1 are sequentially switched. FIG. 3 schematically shows the state where the positioning subject of the magnetic scale C1 moving from the left side to the right side 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 between the magnetic sensors S1 and S2 is performed in a state where the scale body AB1 of the magnetic scale C1 straddles the detection ranges of two adjacent magnetic sensors S1 and S2. In the illustrated example, at the timing when the magnetic sensors S1 and S2 are at symmetric positions SW1 and SW2 with respect to the center (the position of the reference mark Z1) in the moving direction of the magnetic scale C1, the positioning subject of the magnetic scale C1 is switched from the magnetic sensor S1 to the magnetic sensor S2.

[0029] The first switching position SW1 is a position within the scale body AB1 at a predetermined distance from the boundary between the left end portion E1L and the scale body AB1, and the second switching position SW2 is a position within the scale body AB1 at a predetermined distance from the boundary between the right end portion E1R and the scale body AB1. In the illustrated example, the distance from the left end of the scale body AB1 of the first switching position SW1 and the distance from the right end of the scale body AB1 of the second switching position SW2 are, for example, 1 mm. In this case, the distance from the center of the scale body AB1 of the first switching position SW1 and the distance from the center of the scale body AB1 of the second switching position SW2 are 15 mm, and the sum (30 mm) thereof coincides with the interval between the magnetic sensors S1 and S2.

[0030] When the positioning subject of the magnetic scale C1 switches from the magnetic sensor S1 to the magnetic sensor S2, the count value of the counter 51 of the magnetic sensor S1 at the source of movement is taken over by the count value of the counter 52 of the magnetic sensor S2 at the destination of movement. Hereinafter, when each of the magnetic sensors S1 to S5 detects the center of the magnetic scale C1 (the position of the reference mark Z1), the count values of the counters 51 to 55 are set to zero. When each of the magnetic sensors S1 to S5 detects a magnetic scale on the side opposite to the moving direction of the mover C1 from the center of the magnetic scale C1 (the left side in FIG. 3), the count values of the counters 51 to 55 are set to positive. When each of the magnetic sensors S1 to S5 detects a magnetic scale on the side of the moving direction of the mover C1 from the center of the magnetic scale C1 (the right side in FIG. 3), the count values of the counters 51 to 55 are set to negative.

[0031] 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 start count value. In the illustrated example, the switching count value and the start count value differ only in the positive and negative signs. When the first switching position SW1 of the magnetic scale C1 comes above the magnetic sensor S1 in the illustrated state, the switching count value "+15,000" of the counting unit 51 is converted into the start count value "-15,000" of the counting unit 52 of the magnetic sensor S2 located at the second switching position SW2. Thereafter, the magnetic sensor S2 becomes the main body for measuring the position of the magnetic scale C1, and its counting unit 52 counts from the start count value "-15,000" to the next (to the magnetic sensor S3) switching count value "+15,000".

[0032] The reference mark detection control unit 40 in FIG. 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 according to 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 according to the count values in each of the counting units 51 to 55.

[0033] Before explaining the control of the detection of the reference mark Z1 by the reference mark detection activation unit 41 and / or the reference mark detection deactivation 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, it is necessary to specify or register the reference position or the initial position of the mover C1 by detecting the reference mark Z1 of the magnetic scale C1 by any one of a plurality of magnetic sensors (S1 and S2 in the example of FIG. 4). Each of the magnetic sensors S1 and S2 must surely detect the reference mark Z1 and identify that the reference mark Z1 belongs to the mover C1. Therefore, in order to prevent misdetection of the reference mark Z1 and / or the mover C1, each of the magnetic sensors S1 and S2 is in a state where it cannot detect the reference mark Z1 in principle, and the detection of the reference mark Z1 is activated only when the reference mark Z1 and the mover C1 can surely be detected.

[0034] As shown in FIG. 4, assume that the mover C1 with an unregistered initial position in the linear conveyance system 1 moves along the rail from the left side to the right side of the magnetic sensor S1. The position of the magnetic scale C1 in the state of FIG. 4 is not above any of the magnetic sensors S1 and S2, and is shown as "left of S1" in FIG. 5. In this "left of S1" state, since neither of the magnetic sensors S1 and S2 detects the A / B-phase magnetic scale of the magnetic scale C1, "S1 - A / B phase" and "S2 - A / B phase" in FIG. 5, which schematically represent 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 portion E1R of its magnetic scale C1 comes above the magnetic sensor S1, the magnetic sensor S1 detects the A / B phase magnetic graduations formed on the right end portion 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 of FIG. 5, when the "scale position" of the magnetic scale C1 switches from "left of S1" to "above S1", the "S1 - A / B phase" representing the count value of the counter 51 increases from "1" to "12". In this state of "above S1", since the magnetic scale C1 is not above the magnetic sensor S2 and the magnetic sensor S2 does not detect the A / B phase magnetic graduations of the magnetic scale C1, the "S2 - A / B phase" representing the count value of the counter 52 remains "0". In this embodiment, for simplicity of explanation, it is assumed that the count value "18" represents the full length of one magnetic scale, but the count value per magnetic scale in the actual linear conveyance system 1 is very large, for example, about "30,000" ("-15,000" to "+15,000") as described above with respect to FIG. 3.

[0036] The "Z" that appears in the "S1 - Z phase" column when the count value of "S1 - A / B phase" in FIG. 5 becomes "9" means that the reference mark Z1 has come above the magnetic sensor S1. However, as described above, the magnetic sensor S1 is in a state where it cannot detect the reference mark Z1 in principle ("S1 - Z detection" is "impossible"), so the reference mark Z1 is not detected when the count value of "S1 - A / B phase" becomes "9".

[0037] When the count value of "S1-A / B phase" in Fig. 5 is between "13" and "18", the magnetic scale C1 is in the state of "on S1 & S2", that is, on both of the magnetic sensors S1 and S2. Specifically, the part of the magnetic scale C1 to the left of the reference mark Z1 (the left end E1L and the left part of the scale body AB1) is on the magnetic sensor S1, and the part of the magnetic scale C1 to the right of the reference mark Z1 (the right end E1R and the right part of the scale body AB1) is on the magnetic sensor S2. In this "on S1 & S2" state, since both of the magnetic sensors S1 and S2 detect the A / B-phase magnetic scale of the magnetic scale C1, "S1-A / B phase" and "S2-A / B phase" representing the count values of the respective counting parts 51 and 52 both increase in the same way.

[0038] In this embodiment, when "S1-A / B phase" and "S2-A / B phase" increase or decrease continuously by a predetermined count value (in the illustrated example, by "3" count values) in the same direction at substantially the same timing, the detection of the reference mark Z1 by the magnetic sensor on the moving direction side of the increase or decrease direction, that is, the moving direction of the mover C1, is enabled. In the illustrated example, since the increase of "S1-A / B phase" from "13" to "15" and the increase of "S2-A / B phase" from "1" to "3" occur continuously by "3" count values at substantially the same timing, the detection of the reference mark Z1 by the magnetic sensor S2 on the moving direction side (that is, the right side) of the mover C1 from the left side to the right side is enabled. Thus, "S2-Z detection" switches from "inaccessible" to "accessible" after the count value of "S2-A / B phase" reaches "4".

[0039] When the count value of "S2-A / B phase" reaches "9" in this state, the reference mark Z1 comes onto the magnetic sensor S2 (the letter "Z" appears in the column of "S2-Z phase"), 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", since the magnetic scale C1 has passed the magnetic sensor S1 to the right, the "scale position" is "on S2", which means that the magnetic scale C1 is only on 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 embodiments of FIGS. 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 change continuously by a predetermined count value in the same direction at substantially the same timing. Therefore, the reference mark Z1 of the mover C1 detected simultaneously by both magnetic sensors S1 and S2 can be surely detected by the magnetic sensor S2 at the moving destination. However, when two movers close to each other are moving at the same speed, a situation may occur where the count values of two adjacent magnetic sensors that individually detect each mover change continuously by a predetermined count value in the same direction at substantially the same timing. Therefore, there remains a possibility of erroneously detecting the reference mark and / or the mover. According to the present embodiment described below, the possibility of erroneously detecting the reference mark and / or the mover can be further reduced by the configuration shown in FIG. 2 (particularly, the reference mark detection enabling unit 41 and / or the reference mark detection disabling unit 42).

[0041] In FIG. 2, based on the count values in each counting unit 51 to 55, the reference mark detection enabling unit 41 enables the detection of the reference marks Z1 and Z2 by the other magnetic sensors S1 to S5 when the magnetic scales C1 and C2 move out of the detection range of one of the magnetic sensors S1 to S5 from a state where they straddle the detection ranges of two adjacent magnetic sensors S1 / S2, S2 / S3, S3 / S4, and S4 / S5.

[0042] In the simple embodiments shown in FIGS. 6 and 7, based on the count values in the counting units 51 and 52 (not shown in FIG. 6), when the magnetic scale C1 moves out of the detection range of one of the magnetic sensors S1 from a state where it straddles the detection ranges of two adjacent magnetic sensors S1 / S2 as shown by the dashed line, the reference mark detection enabling unit 41 enables the detection of the reference mark Z1 by the other magnetic sensor S2 on the moving direction side of the mover C1.

[0043] As shown in FIG. 7, when the reference mark detection enabling unit 41 determines that the count values of the counting units 51 and 52 in two adjacent magnetic sensors S1 and S2 change in the same manner as in FIG. 5 (in the example shown in the figure, while the count value of the magnetic sensor S1 increases from "13" to "15", the count value of the magnetic sensor S2 increases from "1" to "3"), it is determined that the magnetic scale C1 is in the state of "on S1 & S2" straddling two adjacent detection ranges. The magnetic scale C1 in this "on S1 & S2" state is on both of the magnetic sensors S1 and S2 as shown by the solid line in FIG. 6. At this time, the reference mark Z1 is located at a position sandwiched between the detection ranges of two adjacent magnetic sensors S1 and S2.

[0044] As shown in FIG. 7, the state of "on S1 & S2" where the magnetic scale C1 straddles 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". Further, when only the count value of the magnetic sensor S2 increases to "7" while the count value of the magnetic sensor S1 remains at "18", 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 enters the state of "on S2" as shown by the dashed line in FIG. 6. Therefore, the reference mark detection enabling unit 41 enables the detection of the reference mark Z1 by the other magnetic sensor S2 on the moving direction side of the mover C1 at the timing when only the count value of the magnetic sensor S2 increases to "7". Note that the reference mark detection enabling unit 41 may also enable the detection of the reference mark Z1 by the other magnetic sensor S2 on the moving direction side of the mover C1 at the timing when the magnetic sensor S1 can no longer detect the A / B phase magnetic scale of the magnetic scale C1.

[0045] At this point, the reference mark Z1 is still in a position sandwiched between the detection ranges of two adjacent magnetic sensors S1 and S2 as shown by the dashed line in FIG. 6. Therefore, when the mover C1 moves further in the same direction, the reference mark Z1 comes above the magnetic sensor S2. Specifically, when the count value of the magnetic sensor S2 becomes "9", the reference mark Z1 comes above the magnetic sensor S2 (the "Z" appears in the column of "S2-Z phase"). Thus, 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. The reference mark detection disabling unit 42 in FIG. 2 disables the detection of the reference mark Z1 by the other magnetic sensor S2 on the moving direction side, which was enabled by the reference mark detection enabling unit 41 at the S2 count value of "7", when the other magnetic sensor S2 detects the reference mark Z1 at the S2 count value of "9" (sets "S2-Z detection" to "disabled") after the S2 count value of "10".

[0046] Subsequently, the case where there are a plurality of movers will be described. In this case, since there is a possibility that two movers (i.e., magnetic scales) close to each other may simultaneously enter the detection range of one magnetic sensor, it is preferable to take measures in advance to prevent misdetection of each magnetic scale as shown in FIG. 8.

[0047] In FIG. 8, a state is schematically shown where two magnetic scales C1 and C2 that have approached each other to the minimum approachable distance are simultaneously within the detection range R of one magnetic sensor S1 to S5. In this example, the minimum approachable 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 (the left-right direction in FIG. 8) is 5 mm. As described above, since A / B-phase magnetic graduations are formed at the right end E1R of the magnetic scale C1 and the left end E2L of the magnetic scale C2, similar to the scale main bodies AB1 of the magnetic scale C1 and AB2 of the magnetic scale C2, in the illustrated state, the magnetic sensors S1 to S5 detect the A / B-phase magnetic graduations at the right end E1R and the A / B-phase magnetic graduations at the left end E2L simultaneously. In this case, the magnetic sensors S1 to S5 cannot distinguish and detect the two magnetic scales C1 and C2.

[0048] In order to prevent false detection of the two closely adjacent magnetic scales C1 and C2 in this way, shielding members B1R and / or B2L for shielding 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 are provided.

[0049] The shielding member B1R shields the A / B-phase magnetic scale provided at least on the right end side far from the scale main body AB1 at the right end E1R of the magnetic scale C1. Specifically, as described above, in the right end E1R with a total length of 8 mm, the right end side portion 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 in the track direction (5 mm) of the detection range R of the magnetic sensors S1 to S5, 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. Also, if the length of the shielding member B1R in the track direction is equal to or greater than the length obtained by subtracting the minimum approachable distance (2 mm) of the movers C1 and C2 from the length in the track direction (5 mm) of the detection range R of the magnetic sensors S1 to S5 (3 mm), the shielding member B1R alone can 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. Further, if the length of the shielding member B1R in the track direction is equal to or greater than half (1.5 mm) of the length obtained by subtracting the minimum approachable distance (2 mm) of the movers C1 and C2 from the length in the track direction (5 mm) of the detection range R of the magnetic sensors S1 to S5 (3 mm), together with the shielding member B2L of the same length, the detection range R of the magnetic sensors S1 to S5 can be substantially shielded, preventing the magnetic scale C1 from being detected simultaneously with the magnetic scale C2.

[0050] The shielding member B2L shields the A / B-phase magnetic scale provided at least on the left end side far from the scale main body AB2 at the left end E2L of the magnetic scale C2. Specifically, as described above, among the left end E2L with a total length of 8 mm, the left end side portion 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 in the track direction (5 mm) of the detection range R of the magnetic sensors S1 to S5, 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. Also, if the length of the shielding member B2L in the track direction is equal to or greater than the length obtained by subtracting the minimum approachable distance (2 mm) of the movers C1 and C2 from the length in the track direction (5 mm) of the detection range R of the magnetic sensors S1 to S5 (3 mm), the shielding member B2L alone can 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. Further, if the length of the shielding member B2L in the track direction is equal to or greater than half (1.5 mm) of the length obtained by subtracting the minimum approachable distance (2 mm) of the movers C1 and C2 from the length in the track direction (5 mm) of the detection range R of the magnetic sensors S1 to S5 (3 mm), together with the shielding member B1R of the same length, it can 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 the ferromagnetic material include metals and alloys such as iron, cobalt, nickel, gadolinium, and manganese. When an optical scale is used instead of the magnetic scale as the positioning scale, the shielding member may be formed of a light-shielding material that optically shields the optical sensor as the position detection unit. As described above, by taking the measures as shown in FIG. 8, even if the ends of the positioning scales of two adjacent movers 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 simultaneously misdetected by the position detection unit.

[0053] Subsequently, in the embodiments of FIGS. 4 and 5 (embodiments that do not use the reference mark detection activation unit 41 and / or the reference mark detection inactivation unit 42), a plurality of embodiments will be described in which two adjacent movers that may misdetect the reference mark and / or the mover are moving at a constant speed.

[0054] In the first embodiment shown in FIGS. 9 and 10, in the initial state shown in FIG. 9 (a state in which the movers C1 and C2 with unregistered initial positions start moving rightward), the mover C1 is on both of the magnetic sensors S2 and S3, and the mover C2 is on the magnetic sensor S4. As shown in FIG. 10, based on the count values in the counting units 52 and 53, when the magnetic scale C1 moves out of the detection range of one magnetic sensor S2 from a state where it straddles the detection ranges of two adjacent magnetic sensors S2 / S3, the reference mark detection activation unit 41 enables the detection of the reference mark Z1 by the other magnetic sensor S3 on the moving direction side of the mover C1.

[0055] When the mover C1 further moves in the same direction in this state, since the reference mark Z1 comes onto the magnetic sensor S3, 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 disabling unit 42 disables the detection of the reference mark Z1 by the magnetic sensor S3. After this, a situation occurs where the magnetic scale C1 moves out of the detection range of one of the magnetic sensors S3 / S4 from a state where it straddles the detection ranges of two adjacent magnetic sensors S3 / S4. However, since 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 enabled.

[0056] On the other hand, when the magnetic scale C2 moves out of the detection range of one of the magnetic sensors S4 / S5 from a state where it straddles the detection ranges of two adjacent magnetic sensors S4 / S5, based on the count values in the counting units 54, 55, the reference mark detection enabling unit 41 enables the detection of the reference mark Z2 by the other magnetic sensor S5 on the moving direction side of the mover C2. When the mover C2 further moves in the same direction in this state, since the reference mark Z2 comes onto the magnetic sensor S5, the reference mark Z2 is detected by the magnetic sensor S5 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 S5, the reference mark detection disabling unit 42 disables 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 are moving at the same speed, the reference marks Z1 and Z2 of each mover C1 and C2 can be reliably detected.

[0057] In the second embodiment shown in FIGS. 11 and 12, in the initial state shown in FIG. 11, the mover C1 is on the magnetic sensor S2, and the mover C2 is on both of the magnetic sensors S3 and S4. As shown in FIG. 12, based on the count values in the counting units 53 and 54, when the magnetic scale C2 moves out of the detection range of one of the magnetic sensors S3 from the state where it straddles the detection ranges of two adjacent magnetic sensors S3 / S4, the reference mark detection enabling unit 41 enables the detection of the reference mark Z2 by the other magnetic sensor S4 on the moving direction side of the mover C2.

[0058] When the mover C2 further moves in the same direction in this state, since the reference mark Z2 comes onto the magnetic sensor S4, 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 disabling unit 42 disables the detection of the reference mark Z2 by the magnetic sensor S4. Although a situation occurs later where the magnetic scale C2 moves out of the detection range of one of the magnetic sensors S4 from the state where it straddles the detection ranges of two adjacent magnetic sensors S4 / S5, since 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 enabled.

[0059] On the one hand, when the magnetic scale C1 moves out of the detection range of one magnetic sensor S2 from a state where it straddles the detection ranges of two adjacent magnetic sensors S2 / S3 based on the count values in the counting units 52 and 53, the reference mark detection enabling unit 41 enables the detection of the reference mark Z1 by the other magnetic sensor S3 on the moving direction side of the mover C1. When the mover C1 further moves in the same direction in this state, since the reference mark Z1 comes onto the magnetic sensor S3, 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 disabling unit 42 disables 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 are moving at a constant speed, the reference marks Z1 and Z2 of the respective movers C1 and C2 can be reliably detected.

[0060] In the third embodiment shown in FIGS. 13 and 14, in the initial state shown in FIG. 13, the mover C1 is on both of the magnetic sensors S1 and S2, and the mover C2 is on both of the magnetic sensors S3 and S4. As shown in FIG. 14, when the magnetic scale C1 moves out of the detection range of one magnetic sensor S1 from a state where it straddles the detection ranges of two adjacent magnetic sensors S1 / S2 based on the count values in the counting units 51 and 52, the reference mark detection enabling unit 41 enables the detection of the reference mark Z1 by the other magnetic sensor S2 on the moving direction side of the mover C1.

[0061] In this state, when the mover C1 further moves in the same direction, the reference mark Z1 comes onto the magnetic sensor S2. Therefore, 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 disabling unit 42 disables the detection of the reference mark Z1 by the magnetic sensor S2. After this, although a situation may occur where the magnetic scale C1 moves out of the detection range of one of the two adjacent magnetic sensors S2 / S3 from a state where it straddles the detection ranges of the two adjacent magnetic sensors S2 / S3, since 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 enabled.

[0062] On the other hand, based on the count values in the counting units 53 and 54, when the magnetic scale C2 moves out of the detection range of one of the two adjacent magnetic sensors S3 / S4 from a state where it straddles the detection ranges of the two adjacent magnetic sensors S3 / S4, the reference mark detection enabling unit 41 enables the detection of the reference mark Z2 by the other magnetic sensor S4 on the moving direction side of the mover C2.

[0063] In this state, when the mover C2 further moves in the same direction, the reference mark Z2 comes onto the magnetic sensor S4. Therefore, 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 disabling unit 42 disables the detection of the reference mark Z2 by the magnetic sensor S4. Although not shown in the figure, after this, a situation may occur where the magnetic scale C2 moves out of the detection range of one of the two adjacent magnetic sensors S4 / S5 from a state where it straddles the detection ranges of the two adjacent magnetic sensors S4 / S5, but since 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 enabled. As described above, even when the two movers C1 and C2 that are close to each other are moving at the same speed, the reference marks Z1 and Z2 of the respective movers C1 and C2 can be reliably detected.

[0064] In the above first to third embodiments, the moving directions of the respective movers C1 and C2 were constant. However, even when the moving directions of the respective movers C1 and C2 change, the reference marks Z1 and Z2 of the respective movers C1 and C2 can be reliably detected. For example, after the other (e.g., right side) magnetic sensor is activated by the reference mark detection activation unit 41, before the other magnetic sensor detects the reference marks Z1 and Z2, if the magnetic scales C1 and C2 return to a state where they straddle the detection ranges of one (e.g., left side) magnetic sensor and the other magnetic sensor, and then move outside the detection range of the other magnetic sensor, the reference mark detection activation unit 41 enables the detection of the reference marks Z1 and Z2 by one magnetic sensor.

[0065] At this time, after the other magnetic sensor is activated by the reference mark detection activation unit 41, before the other magnetic sensor detects the reference marks Z1 and Z2, if the magnetic scales C1 and C2 return to a state where they straddle the detection ranges of one magnetic sensor and the other magnetic sensor, and then move outside the detection range of the other magnetic sensor, the reference mark detection deactivation unit 42 may deactivate the detection of the reference marks Z1 and Z2 by the other magnetic sensor. Alternatively, after the other magnetic sensor is activated by the reference mark detection activation unit 41, before the other magnetic sensor detects the reference marks Z1 and Z2, if the magnetic scales C1 and C2 return to a state where they straddle the detection ranges of one magnetic sensor and the other magnetic sensor, the reference mark detection deactivation unit 42 may deactivate the detection of the reference marks Z1 and Z2 by the other magnetic sensor.

[0066] As described above, the present invention has been described based on the embodiments. It is understood by those skilled in the art that the embodiments are illustrative, and various modifications are possible for each combination of their respective components and each processing process, and such modifications are also within the scope of the present invention.

[0067] In the embodiment, a linear conveyance system that drives a mover based on the magnetic force between a permanent magnet provided on the mover and an electromagnet provided on the stator was exemplified. However, the present invention can be applied to any driving device based on any principle other than magnetism (for example, electricity or fluid).

[0068] Note that the functional configurations of the respective devices described in the embodiment can be realized by hardware resources or software resources, or by the cooperation of hardware resources and software resources. As the hardware resources, a processor, a ROM, a RAM, and other LSIs can be used. As the software resources, programs such as an operating system and an application can be used.

Description of Reference Numerals

[0069] 1 Linear conveyance system, 2 Stator, 3 Mover, 4 Positioning device, 40 Reference mark detection control unit, 41 Reference mark detection activation unit, 42 Reference mark detection deactivation unit, 51 Counter, AB1 Scale body, B1R Shielding member, C1 Magnetic scale, S1 Magnetic sensor, Z1 Reference mark.

Claims

1. A plurality of position detection units arranged along the moving direction of the mover for positioning a positioning scale attached to the mover, the interval between them being smaller than the length of the positioning scale in the moving direction, and a plurality of position detection units for specifying the reference position of the mover by detecting a reference mark provided on the mover. A reference mark detection enabling unit that enables detection of the reference mark by the other position detection unit when the positioning scale moves out of the detection range of one position detection unit from a state where the positioning scale straddles the detection ranges of two adjacent position detection units. A positioning device comprising the above.

2. The positioning device according to claim 1, further comprising a reference mark detection disabling unit that disables detection of the reference mark by the other position detection unit when the other position detection unit, which has been enabled by the reference mark detection enabling unit, detects the reference mark.

3. After the other position detection unit is enabled by the reference mark detection enabling unit and before the other position detection unit detects the reference mark, if the positioning scale returns to a state where it straddles the detection ranges of the one position detection unit and the other position detection unit and then further moves out of the detection range of the other position detection unit, the positioning device according to claim 1 or 2, further comprising a reference mark detection disabling unit that disables detection of the reference mark by the other position detection unit.

4. After the other position detection unit is enabled by the reference mark detection enabling unit and before the other position detection unit detects the reference mark, if the positioning scale returns to a state where it straddles the detection ranges of the one position detection unit and the other position detection unit, the positioning device according to claim 1 or 2, further comprising a reference mark detection disabling unit that disables detection of the reference mark by the other position detection unit.

5. After the other position detection unit is enabled by the reference mark detection enabling unit and before the other position detection unit detects the reference mark, if the positioning scale returns to a state where it straddles the detection ranges of the one position detection unit and the other position detection unit and then further moves out of the detection range of the other position detection unit, the reference mark detection enabling unit enables detection of the reference mark by the one position detection unit. The positioning device according to any one of claims 1 to 4.

6. The positioning scale includes a plurality of graduations provided along the moving direction. The position detection unit includes a counting unit that counts each of the detected graduations. When the count values of the counting units in two adjacent position detection units change in the same manner, the reference mark activation unit determines that the positioning scale spans two adjacent detection ranges. The positioning device according to any one of claims 1 to 5.

7. The reference mark is located at a position sandwiched between the two detection ranges when the positioning scale spans the detection ranges of two adjacent position detection units. The positioning device according to any one of claims 1 to 6.

8. For the positioning device according to any one of claims 1 to 7, each distance between the reference mark and both ends of the positioning scale in the moving direction is smaller than the interval between the plurality of position detection units.

9. A plurality of movers driven along a track, A plurality of position detection units arranged along the track for positioning the positioning scale attached to each mover, the interval of which is smaller than the length of the positioning scale in the track direction, and a plurality of position detection units for specifying the reference position of each mover by detecting a reference mark provided on each mover. A reference mark activation unit that enables the detection of the reference mark by the other position detection unit when the positioning scale moves out of the detection range of one position detection unit from a state where it spans the detection ranges of two adjacent position detection units. A driving device comprising the above.

10. In a positioning device comprising a plurality of position detection units arranged along the moving direction of a mover for positioning a positioning scale attached to the mover, the interval of which is smaller than the length of the positioning scale in the moving direction, and a plurality of position detection units for specifying the reference position of the mover by detecting a reference mark provided on the mover. A positioning method comprising a reference mark activation step of enabling the detection of the reference mark by the other position detection unit when the positioning scale moves out of the detection range of one position detection unit from a state where it spans the detection ranges of two adjacent position detection units.

11. A plurality of position detection units arranged along the moving direction of the mover for positioning a positioning scale attached to the mover, the interval between them being smaller than the length of the positioning scale in the moving direction, and the plurality of position detection units for specifying the reference position of the mover by detecting a reference mark provided on the mover. In the positioning device comprising: A positioning program that causes a computer to execute a reference mark detection enabling step of enabling detection of the reference mark by the other position detection unit when the positioning scale moves out of the detection range of one position detection unit from a state where it straddles the detection ranges of two adjacent position detection units.

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