JPH0541389U - Linear motor for precision positioning device - Google Patents

Abstract

(57) [Abstract] [Purpose] The thrust applied to the coil 2 is made constant regardless of the positional relationship between the coil 2 and the gaps 8, 8 between the permanent magnets 7, 7. [Structure] Permanent magnets 7 and 7 arranged through gaps 8 and 8.
Of the magnetic plates 12, 12 on the side facing the coil 2.
Attach. Even if the coil 2 and the gaps 8 and 8 face each other, the magnetic plates 12 and 12 allow a sufficiently uniform magnetic flux to flow through the coil 2.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The linear motor for a precision positioning device according to the present invention is incorporated in, for example, an integrated circuit manufacturing device and used to translate an XY table.

[0002]

[Prior Art]

 Conventionally, a linear motor as shown in FIGS. 5 and 6 has been used to translate the XY table of the precision positioning device. In this linear motor, a coil 2 is movable along a core assembly 1 made of a magnetic material that forms a magnetic path. In the core assembly 1, the upper core 3 and the lower core 4, which are parallel to each other, are connected at both ends to the upper and lower ends of a pair of side cores 5 and 5, respectively. It is configured by crossing over one center core 6.

On the lower surface of the upper core 3 and the upper surface of the lower core 4, a plurality of permanent magnets 7, 7 magnetized in the up-down direction, respectively, are provided. By providing gaps 8 and 8 between 7 and 7, they are fixed intermittently. Between the lower surfaces of the permanent magnets 7, 7 on the lower surface of the upper core 3 and the upper surface of the center core 6, and between the upper surfaces of the permanent magnets 7, 7 on the upper surface of the lower core 4 and the lower surface of the center core 6, Spaces 9 and 9 are formed along the upper and lower sides 2a and 2b of the rectangular frame-shaped coil 2 which surrounds the center core 6 and are movably inserted into the spaces 9 and 9.

The coil 2 is fixed to one side of an XY table (not shown) by a mounting bracket 11. Therefore, by controlling the power supply to the coil 2, the XY table can be moved along the center core 6.

[0005]

[Problems to be solved by the device]

 By the way, in the case of the conventional linear motor for the precision positioning device, which is constructed and operates as described above, there are the following problems to be solved.

That is, the force F for moving the coil 2 based on the energization of the coil 2 is the magnetic flux density B passing through the coil 2 and the length of the coil 2 extending in the longitudinal direction of the center core 6. When the length is L and the current flowing through the coil 2 is I, it is expressed by F = B.L.I. Of these, the length L is fixed, and the current I can be precisely controlled.

However, the magnetic flux density B is not limited to the case where the coil 2 faces only the permanent magnets 7, 7 and the gap existing between the adjacent permanent magnets 7, 7 as well as the permanent magnets 7, 7. There is a difference between the case of facing 8 and the case of 8 as well. It is unavoidable that the force F (thrust) for moving the coil 2 becomes uneven due to the difference in the magnetic flux density B based on such a cause.

As described above, when the thrust force F for moving the coil 2 differs depending on the position of the coil 2, the positioning accuracy of the XY table coupled to the coil 2 via the mounting bracket 11 is unsatisfactory. It tends to be stable, and it is difficult to improve the positioning accuracy to about 0.1 to 1 μm, for example.

The linear motor for a precision positioning device of the present invention eliminates such non-uniformity of magnetic flux density, which leads to such poor positioning accuracy.

[0010]

[Means for Solving the Problems]

 The linear motor for a precision positioning device of the present invention is similar to the conventional linear motor for a precision positioning device described above, and has a core made of a magnetic material arranged along the driving direction and the above-mentioned drive on the side surface of the core. A plurality of permanent magnets that are intermittently fixed in the direction, and a coil that is movably provided in the driving direction at a position facing the permanent magnets. The member supporting the coil is displaced in the driving direction.

Further, in the linear motor for a precision positioning device of the present invention, a magnetic plate is provided on the side of the plurality of permanent magnets facing the coil on the side facing the coil. It is characterized by being attached.

[0012]

[Action]

 In the case of the linear motor for a precision positioning device of the present invention configured as described above, a magnetic plate is attached to the side of a plurality of permanent magnets facing the coil in a state of being stretched between adjacent permanent magnets. Therefore, even when the coil faces the gap existing between the adjacent permanent magnets, the magnetic flux density interlinking the coils is sufficiently uniform.

Therefore, the thrust applied to the coil does not change due to the positional relationship between the coil and the permanent magnet, and precise positioning of the XY table or the like becomes possible.

[0014]

【Example】

 1 and 2 show an embodiment of the present invention. A plurality of permanent magnets 7, 7 are provided on the lower surface of the upper core 3 and the upper surface of the lower core 4, which form the core assembly 1, and gaps 8, 8 are provided between adjacent permanent magnets 7, 7. It is fixed intermittently in this state. Further, in the linear motor for the precision positioning device of the present invention, the lower side surfaces of the plurality of permanent magnets 7 and 7 fixed to the lower surface of the upper core 3 and the plurality of permanent magnets 7 and 7 fixed to the upper surface of the lower core 4 are used. Magnetic plates 12, 12 each made of a magnetic material are attached to the upper surface of the upper side in a state of being bridged between adjacent permanent magnets 7, 7.

As a result, in the coil 2 coupled and supported by a member driven by a linear motor such as an XY table, both the upper side 2a and the lower side 2b have the permanent magnets 7 via the magnetic plates 12 and 12. , 7 facing. The magnetic plates 12 and 12 are continuous in the moving direction of the coil 2 without interruption.

As described above, since the upper side 2a and the lower side 2b of the coil 2 are opposed to the continuous magnetic plates 12 and 12, the upper side 2a and the lower side 2b of the coil 2 are adjacent to the permanent magnets 7, Even when facing the gap 8 existing between the coils 7, the magnetic flux density linked to the coil 2 becomes sufficiently uniform.

That is, since the magnetic plates 12, 12 have a very high magnetic permeability as compared with air, even if a part of the coil 2 and the gap 8 face each other as shown in FIG. The magnetic flux emitted from the permanent magnets 7, 7 adjacent to each other flows through the magnetic plates 12, 12 to a part of the coil 2. As a result, a constant magnetic flux always flows through the coil 2 regardless of the positional relationship between the coil 2 and the gap 8. On the other hand, in the case where the magnetic plate 12 is not provided and the gap 8 is directly opposed to the coil 2 as in the conventional linear motor described above, as shown in FIG. The density of the magnetic flux flowing in the portion facing the gap 8 becomes low.

As described above, in the linear motor for precision positioning device of the present invention, the magnetic flux density interlinking the coil 2 can always be kept constant, so that the thrust applied to this coil 2 is the coil 2 and the permanent magnet 7. , 7 does not change due to the positional relationship, and precise positioning of the XY table or the like becomes possible. The magnetic plate 12 can be an iron plate, a stainless steel plate, a silicon steel plate, or the like, but a thin film of magnetic material such as amorphous or permalloy can also be used as the magnetic plate 12.

Since other configurations and operations are the same as those of the conventional precision positioning linear motor described above, the same parts are designated by the same reference numerals, and duplicate description will be omitted.

[0020]

[Effect of the device]

 Since the linear motor for the precision positioning device of the present invention is constructed and operates as described above, the thrust force for moving the coil can be made uniform over the moving direction, and the linear motor such as an XY table can be used. It enables precise positioning of the members driven by the motor.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a partially enlarged view showing the flow of magnetic flux in the linear motor of the present invention.

FIG. 4 is a partially enlarged view showing the flow of magnetic flux in a conventional linear motor.

FIG. 5 is a side view showing a conventional structure.

6 is a sectional view taken along line BB of FIG.

[Explanation of sign]

 1 core assembly 2 coil 2a upper side 2b lower side 3 upper core 4 lower core 5 side core 6 center core 7 permanent magnet 8 gap 9 space 11 mounting bracket 12 magnetic plate

Claims (1)

[Scope of utility model registration request] 1. A core made of a magnetic material arranged along the driving direction, a plurality of permanent magnets fixed to the side surface of the core intermittently over the driving direction, and facing the permanent magnet. In a linear motor for a precision positioning device, a coil provided movably in the driving direction is provided at a position to move, and a member supporting the coil is displaced in the driving direction based on energization of the coil. A linear motor for a precision positioning device characterized in that a magnetic plate is attached to a surface of a plurality of permanent magnets facing the coil on a side surface of the permanent magnet in a state of being bridged between adjacent permanent magnets.