JPH07170711A - Positioning device - Google Patents

Abstract

PURPOSE:To provide a positioning device which enables downsizing and flattening and also high-speed and accurate positioning by effectively arranging a linear motor consisting of special constitution. CONSTITUTION:The whole face of a mobile table 30 is substantially made a linear motor part by devising the shape of the yokes (a pair of yokes 22 and 23 are connected and united roughly in H shape by a center yoke 25 positioned at the center of those plate-shaped yokes 22 and 23 so that they may be opposed to each other specified vacant space 24 apart) of a magnetic circuit 21, which constitutes the linear motor to serve as the drive source of a mobile stable 30, and arrangement, constitution, etc., of a permanent magnet 26 and a mobile table 27. Especially, large thrust generated in the mobile coil 27 is made to work efficiently upon the mobile table 30 by arranging a bearing 32, which supports the magnetic circuit and the mobile table capably of shifting relatively, in the specified position of the yoke, etc., which constitute the linear motor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a positioning device for moving various materials to a predetermined position in a wide range of fields such as robots, machine tools and semiconductor devices. The present invention relates to a positioning device having a table, which enables a compact and flattening and a high-speed and high-accuracy positioning by effectively disposing a linear motor having a special configuration.

[0002]

2. Description of the Related Art As a positioning device having a movable table movably arranged in one axis, a movable table 3 is moved by a predetermined amount via a ball screw 2 connected to a stepping motor 1 as shown in FIG. The configuration is known. In the figure, 4 is a bed. That is, the moving table 3 is moved in a predetermined uniaxial direction by converting the rotational movement of the stepping motor 1 into a linear movement by the ball screw 2.

FIG. 7 shows the structure of another positioning device, which comprises a voice coil type linear motor (hereinafter referred to as VCM) 10 as a drive source for a moving table. The VCM 10 comprises a magnetic circuit unit 11 and a movable coil 12, and the movable coil 12 is integrally connected to a moving table 13 which is arranged on a bed 14 so as to be movable in one axis direction by a predetermined means. That is, the linear motion of the movable coil 12 which constitutes the VCM 10 is directly transmitted to the moving table 13 to move the moving table 13 in a predetermined uniaxial direction.

[0004]

In recent years, in these positioning devices, not only downsizing but also flattening is strongly desired according to the application, and there is a strong demand for improvement in responsiveness. It is desired to realize high-speed and highly accurate positioning. In the positioning device using the stepping motor 1 shown in FIG. 6 described above,
In order to move the moving table 3 at high speed, it is necessary to increase the acceleration of the moving table 3. The acceleration is determined by the ratio (m / F) of the inertial mass (m) of the moving table 3 and the torque (F) of the stepping motor 1, and the inertial mass (m) of the moving table 3 is set to be as small as possible. It is required that the torque (F) be as large as possible.

However, the stepping motor 1 and the moving table 3 are arranged in series via the ball screw 2, and in order to convert the rotary motion of the stepping motor 1 into a linear motion, the connection between the ball screw 2 and the moving table 3 is required. Since it is indispensable, there is a limit to the reduction of the inertial mass of the moving table 3. The torque of the stepping motor 1 is usually
It is proportional to about the square of the motor diameter and about the length of the motor.
Therefore, reducing the diameter of the stepping motor 1 in order to flatten the motor 1 itself leads to a significant decrease in torque. On the other hand, if an attempt is made to increase the torque by increasing the length, the protruding portion of the motor 1 becomes extremely large, and it is not possible to reduce the size of the positioning device as a whole. As described above, in the positioning device using the stepping motor 1 shown in FIG. 6, it is difficult to satisfy both the small flatness and the high speed.

In the above-described positioning device using the VCM 10 shown in FIG. 7, since the movable coil 12 and the moving table 13 constituting the VCM 10 are directly connected to each other, the moving table is different from the positioning device shown in FIG. The reduction of the inertial mass of 13 is relatively easy to realize. But,
The torque of the VCM 10 depends on the magnetic flux density (B) in the magnetic field in which the moving coil 12 is arranged, the conductor length (L) of the conductors forming the moving coil 12 and the moving coil 12 in the magnetic field. The product of the current (A) to be applied (B × L
XA), the length of the movable coil 12 is increased in the moving direction in order to realize the torque improvement by improving the shape configuration of the magnetic circuit without increasing the overall height of the VCM 10. Is required. Therefore, as the length of the movable coil 12 increases, the length of the magnetic circuit unit inevitably increases, and the magnetic circuit unit is configured to form a smooth magnetic path without saturating the magnetic flux generated from the permanent magnet. It is necessary to make each yoke thick, and as a result, the height of the VCM 10 is increased.

The present invention solves the drawbacks of the conventional positioning device as described above, and in particular, by effectively arranging the linear motor having a special structure, it is possible to reduce the size and flattening. It is an object of the present invention to propose a positioning device that enables high-speed and highly accurate positioning.

[0008]

According to the present invention, the yoke shape of a magnetic circuit portion forming a linear motor which is a driving source of a moving table, the arrangement of permanent magnets and a movable coil, and the like are substantially devised. The lower surface of the moving table is used as a linear motor section, and in particular, by arranging a bearing section that relatively movably supports the magnetic circuit section and the moving table at a predetermined position such as a yoke that constitutes the linear motor, The large thrust force generated in the coil can be directly and efficiently applied to the moving table, thus achieving the above object.

That is, according to the present invention, in a positioning device having a movable table movably arranged in one axis direction, a pair of flat plate-like yokes which face each other and form a predetermined gap are connected and integrated by a central yoke. A magnetic structure in which a pair of flat plate-shaped permanent magnets having different magnetic poles adjacent to each other in the moving direction of the moving table are fixed to at least one opposing surface of the pair of flat plate-shaped yokes at symmetrical positions with respect to the central yoke. The magnetic circuit section and the moving table are relatively disposed, each having a circuit section and a pair of flat movable coils that are integrally connected to and held by the moving table and are arranged in the gap so as to face the flat permanent magnets. It is a positioning device characterized in that it is arranged so as to be movable.

[0010]

The positioning device of the present invention will be described in detail with reference to an embodiment shown in FIGS. 1 is a vertical cross-sectional explanatory view, and FIG. 2 is a aa horizontal cross-sectional explanatory view of FIG. In the positioning device 20 of the present invention, substantially the entire lower surface of the moving table 30 is used as a linear motor section, and the linear motor is composed of a magnetic circuit section 21 and a movable coil 27 integrally arranged on the moving table 30. Further, a bearing 32 is provided at a predetermined position of a yoke forming the magnetic circuit unit 21 so that the magnetic circuit unit 21 and the moving table 30 are arranged so as to be relatively movable.

The magnetic circuit section 21 will be described in detail. First, in the yoke for forming a magnetic path, the pair of flat plate-shaped yokes 22 and 23 are arranged so as to face each other with a predetermined gap 24 formed therebetween. Central yoke 25 located in the central part of
Is connected and integrated in a substantially E shape. In the present invention, the fact that the yoke is substantially E-shaped means that the yoke cross-sectional shape of the main portion for forming the magnetic path is substantially E-shaped, and means for arranging bearings described later and various other members are arranged. Therefore, it is not necessary that the overall yoke cross-sectional shape be substantially E-shaped due to the additional means. Further, the pair of flat plate-shaped yokes 22 and 23 and the central portion yoke 25 may be assembled independently, but for example, the pair of flat plate-shaped yokes 2 may be assembled.
It is desirable to appropriately select one in consideration of the shape and size of each yoke, the assembling workability, the workability, and the like such that one of the Nos. 2 and 23 and the central yoke 25 are integrally formed.

A flat movable coil 27, which will be described later, is arranged in the gap 24. A permanent magnet is used as a magnetic field generating means for applying a propulsive force to the flat movable coil 27, and the flat magnets of the flat yokes 22, 23 are used. It is necessary to place it in a predetermined position. In the present invention, the central yoke 25
And a pair of flat plate-shaped yokes 22, 2 which are symmetrical with respect to each other.
The moving table 30 is provided on at least one of the facing surfaces of the moving table 30.
Direction (arrow direction in the figure: since the moving direction of the moving table 30 and the moving direction of the movable coil 27 are the same, the moving direction of the flat movable coil 27 is shown in the figure)
A pair of flat permanent magnets having different magnetic poles adjacent to each other are fixed to each other. In the figure, of the pair of flat plate-shaped yokes 22 and 23, the pair of flat plate-shaped permanent magnets 26 and 2 are symmetrically positioned on the lower yoke 22 via the central yoke 25.
6 is stuck. The pair of flat plate-shaped permanent magnets 26, 26 are magnetized in the thickness direction, and have different magnetic poles adjacent to each other in the moving direction of the moving table 30, 26a, 26b and 26c, respectively.
It is composed of 26d. These 26a, 26b (2
6c, 26d) can also be obtained by magnetizing a single plate-shaped permanent magnet so that different magnetic poles are adjacent to each other, but 26a and 26b (26c and 26d) may be constituted by independent magnets.

Further, in the figure, the pair of flat plate-shaped permanent magnets 26, 26 has been described as being arranged on the yoke 22 located at the lower part, but it is arranged on the yoke 23 located at the upper part and the central part yoke 25. Both sides of the central yoke 25, such as a configuration in which one is disposed in the yoke 22 located in the lower portion and the other is disposed in the yoke 23 located in the upper portion, a configuration in which it is disposed on either of the facing surfaces of the upper portion and the lower portion, etc. A structure in which substantially the same magnetic field strength acts on the flat movable coils 27, 27 located in the voids 24, 24 formed in
That is, it is sufficient that they are arranged symmetrically with respect to the central portion yoke 25, and it is desirable to appropriately select their arrangement configuration in consideration of the magnetic characteristics of the permanent magnets, the assembly workability, and the like. Further, various known materials can be applied to the material of the flat plate-like permanent magnet, and in particular, in the present invention aiming at miniaturization and flattening, a neodymium rare earth magnet excellent in magnetic characteristics, for example, having a maximum energy product of 30 MGOe or more. Use of is preferred.

In the magnetic circuit portion 21 having the above-mentioned yoke structure and magnet arrangement, for example, the magnetic path formed by the flat plate permanent magnet 26b in the figure will be described. A magnetic path composed of the magnet 26b, the lower yoke 22, the central yoke 25, the upper yoke 23, and the plate-shaped permanent magnet 26b is formed to form a magnetic field having a predetermined strength in the gap 24. The magnetic path formed by the flat plate-shaped permanent magnet 26d is as shown by the broken line B in the figure. The magnetic path formed by the flat plate permanent magnet 26a is the magnetic path in the direction opposite to the broken line a in the figure, and the magnetic path formed by the flat plate permanent magnet 26c is the magnetic path in the direction opposite the broken line b in the figure. .

A void 24 formed in the magnetic circuit portion 21.
Inside thereof, a pair of flat movable coils 27, 27 are arranged facing the flat permanent magnets 26, 26, respectively. More specifically, in order to make the magnetic field action on the flat movable coils 27, 27 uniform (the torque is constant) when the flat movable coils 27, 27 move, the illustrated magnetic field is applied. As described above, only the portions (short portions in FIG. 2) corresponding to the direction perpendicular to the moving direction in the respective flat movable coils 27, 27 have different magnetic pole portions (26a and 26b and 26c and 26d) of the flat plate-shaped permanent magnets 26 and 26. It is desirable to place it so that it is located directly above. The above-mentioned flat movable coils 27, 27 are respectively coil holders 28,
It is held at 28, but is further connected integrally with the moving table 30 by connecting members 29, 29. That is, the linear movement of the flat movable coils 27, 27 is the linear movement of the direct movement table 30.

The moving table 3 integrated with the magnetic circuit section 21 and the flat movable coils 27, 27 described above.
0 means that a well-known bearing means is arranged between, for example, at least one of the pair of flat plate-shaped yokes 22 and 23 forming the magnetic circuit portion 21 and the moving table 30, so that the bearing means is relatively moved through the bearing. Arranged freely. In the drawing, a configuration is shown in which the bearing 32 is arranged between the bearing support portions 31 and 31 standing upright on both side ends of the flat plate-shaped yoke 22 located below and the both side ends of the moving table 30. In the configuration described above, the flat movable coils 27, 27
When a current in a predetermined direction is applied to the flat movable coils 27, 27 by the interaction with the magnetic field in the air gap 24, the movable table 30 integrally connected to the flat movable coils 27, 27 is moved in a predetermined uniaxial direction. Move to.

3, 4, and 5 are partial vertical cross-sectional explanatory views showing another embodiment of the present invention. In any of the configurations, the configuration of the magnetic circuit portion 21 is basically the same, and the arrangement configuration of the bearing 32 that displaces the moving table 30 and the magnetic circuit portion 21 relatively freely is different. Figure 3
This is a configuration in which a bearing 32 is disposed between the movable table 30 and a flat plate-shaped yoke 23 located above the magnetic circuit portion 21, and in the figure, the side end outer peripheral surface of the flat plate-shaped yoke 23 and the movable table 30 are shown. The bearing 32 is disposed between the inner peripheral surface of the side end and the flat permanent magnet 26 is also fixed to the inner side surface of the flat yoke 23 located above.

FIG. 4 shows a structure in which a bearing 32 is disposed between a movable table 30 and a flat plate-shaped yoke 22 located below the magnetic circuit part 21. In the figure, a side end of the flat plate-shaped yoke 22 is shown. The bearing 32 is arranged between the outer peripheral surface and the inner peripheral surface of the side end of the moving table 30, and the flat movable coil 27 moves directly through the coil holder 28 without using the connecting member 29 in FIG. It is integrally connected to the table 30. FIG. 5 shows a non-magnetic material (for example, Al or Al alloy) on which the magnetic circuit portion 21 is fixedly arranged.
The bearing 32 is arranged between the base member 33 and the moving table 30, and in the figure, the inner peripheral surface of the bearing support portion 34 standing on the side end of the base member 33 and the moving table 30 side. The bearing 32 is arranged between the outer peripheral surface and the end. In any of the configurations, it is possible to obtain the same effect as that of the positioning device having the structure shown in FIGS. 1 and 2. Further, in the configurations other than those shown in the drawings, the movement table 30 can be smoothly moved in one axis direction. However, it is desirable to appropriately select the bearings in consideration of the mounting of the bearings and the processing work of the flat yokes 22 and 23.

[0019]

[Embodiment] The maximum energy product of the permanent magnet, which is the magnetic field generation source of the motor for applying thrust to the moving table, is 36M.
A neodymium-based rare earth magnet made of GOe was used, and the positioning device of the present invention shown in FIG. 1 and the ten-positioning device shown in FIG. 6 and FIG. The maximum speed of the moving table was measured. It should be noted that the resolution can be reduced to 1 μm by arranging a predetermined position sensor in each positioning device.
The above measurement was performed in a configuration in which the motor height was 40 mm, and the stroke of the moving table was ± 20 mm.

The maximum speed of the moving table in the positioning device shown in FIG. 6 was about 20 mm / sec, and the maximum speed of the moving table in the positioning device shown in FIG. 7 was about 200 mm / sec. It has been confirmed that the positioning device according to the present invention, which can be occupied in FIG. 1 in comparison with these conventional positioning devices, is capable of extremely high-speed response with the maximum speed of the moving table being 450 mm / sec or more. Therefore, further flattening is possible if the same characteristics as the conventional one are obtained,
For example, even when the motor height is 30 mm, the maximum speed (about 420 mm / sec) that is more than twice the maximum speed of the moving table in the positioning device shown in FIG. 7 can be obtained.
Substantially, it is possible to flatten the thickness to about 1/2 of the conventional thickness.

[0021]

As is apparent from the above embodiments, the present invention devises the yoke shape of the magnetic circuit portion forming the linear motor which is the drive source of the moving table and the arrangement of permanent magnets and movable coils. As a result, substantially the entire lower surface of the moving table is used as the linear motor section, and the thrust is increased by lengthening the substantial conductor length of the movable coil located in the magnetic field without particularly increasing the magnetic circuit section. In addition to the realization, by arranging the bearing part that movably supports the moving table at a predetermined position such as a yoke forming a linear motor, it becomes possible to efficiently apply thrust to the moving table directly connected to the moving coil. In addition, since the inertial mass of the moving table itself can be reduced, the flatness required for positioning devices has been reduced in recent years, and at the same time, high speed One highly accurate positioning can allow the.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view showing an embodiment of a positioning device of the present invention.

2 is a cross-sectional explanatory view showing an embodiment of the positioning device of the present invention, and is a cross-sectional explanatory view taken along the line aa of FIG.

FIG. 3 is a partial cross-sectional explanatory view showing another embodiment of the positioning device of the present invention.

FIG. 4 is a partial cross-sectional explanatory view showing another embodiment of the positioning device of the present invention.

FIG. 5 is a partial cross-sectional explanatory view showing another embodiment of the positioning device of the present invention.

FIG. 6 is a perspective explanatory view showing a conventional positioning device using a stepping motor.

FIG. 7 is a perspective explanatory view showing a conventional positioning device using a voice coil type linear motor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 stepping motor 2 ball screw 3,13,30 moving table 4,14 bed 10 VCM (voice coil type linear motor) 11,21 magnetic circuit part 12 moving coil 22,23 flat plate yoke 24 void 25 central part yoke 26, 26a, 26b, 26c, 26d Flat plate permanent magnet 27 Flat moving coil 28 Coil holder 29 Coupling member 31, 34 Bearing support portion 32 Bearing 33 Base member

Claims (1)

[Claims] 1. A positioning device having a movable table movably arranged in a uniaxial direction, wherein a pair of flat plate-shaped yokes facing each other with a predetermined gap are connected and integrated by a central yoke, and the central yoke is formed. A magnetic circuit portion formed by fixing a pair of flat plate-shaped permanent magnets having different magnetic poles adjacent to each other in the moving direction of the moving table to at least one opposing surface of the pair of flat plate-shaped yokes at positions symmetric with respect to each other;
A pair of flat movable coils, which are integrally connected to and held by the moving table, are arranged in the gap so as to face the flat permanent magnets, respectively, and the magnetic circuit section and the moving table are relatively movable. A positioning device characterized by being arranged.