CN113965041A

CN113965041A - Voice coil motor

Info

Publication number: CN113965041A
Application number: CN202011381314.2A
Authority: CN
Inventors: 胡兵; 江旭初; 吴火亮; 蒋赟
Original assignee: Shanghai Yinguan Semiconductor Technology Co Ltd
Current assignee: Shanghai Yinguan Semiconductor Technology Co Ltd
Priority date: 2020-12-01
Filing date: 2020-12-01
Publication date: 2022-01-21

Abstract

The invention discloses a voice coil motor, which is characterized by comprising: central magnetic steel; at least one end magnetic steel, which is located at least one of the two axial ends of the central magnetic steel and axially spaced from the corresponding axial end of the central magnetic steel, and the center line of the end magnetic steel is arranged to coincide with the center line of the central magnetic steel; the coil is cylindrical and is positioned outside the central magnetic steel and is radially spaced from the central magnetic steel; the outer magnetic ring magnetic steel is cylindrical and is positioned outside the coil and is radially spaced from the coil. The voice coil motor has high thrust density, can further reduce the temperature rise of the voice coil motor and improve the motion performance of the vertical module, and simultaneously, the gravity compensation structure can generate large-stroke and small-fluctuation magnetic levitation force matched with the voice coil motor.

Description

Voice coil motor

Technical Field

The invention relates to the field of motors, in particular to a voice coil motor.

Background

In recent years, with the rapid increase of the market scale of the semiconductor industry, the integration degree of large-scale integrated circuit devices is continuously improved, the precision requirement of a workpiece table is continuously improved, the space constraint and the motion precision requirement of the workpiece table are more and more strict, and meanwhile, the motion stroke of a vertical module of the workpiece table is increased year by year along with the improvement of the requirement of the workpiece table, such as a photoetching device, a film thickness detection device and the like. The voice coil motor with the vertical gravity compensation function is also continuously updated in an iterative mode, and the requirements for the voice coil motor with large stroke and small thrust fluctuation are more urgent. At the present stage, the gravity compensation structure in the voice coil motor generally adopts two schemes: mechanical springs and magnetic levitation gravity compensation structures.

The vertical voice coil motor in US9172291B2 uses a mechanical spring and a magnetic levitation compensation device to compensate gravity in cooperation. In the patent, the magnetic suspension compensation device is used as a magnetic spring, and the magnetic spring is axially coupled with a mechanical spring to compensate the gravity of a motion mechanism. However, the device has certain difficulty in design and manufacture, the restoring force of the mechanical spring and the restoring force of the magnetic suspension mechanism are not easy to couple in the axial direction, the stroke of the voice coil motor is small, and certain limitations exist in engineering application.

In US2009066168a1, a vertical voice coil motor uses a magnetic levitation compensation device to compensate the gravity of a rotor shaft. The coils of the voice coil motor are distributed on the inner wall of the stator magnetic steel at equal intervals, and part of gravity of the motion mechanism is compensated through the magnetic levitation compensation device, so that the temperature rise of the voice coil motor is reduced, and the thrust density of the voice coil motor is improved. Although the stroke of the structure reaches 10mm, the magnetic levitation force amplitude of the magnetic levitation compensation device is small and the fluctuation is too large, so that the thrust fluctuation of the vertical voice coil motor is seriously influenced, and the application field of the voice coil motor is limited.

In chinese patent CN201410331239, the voice coil motor adopts a magnetic levitation gravity compensation structure to compensate partial gravity of the motion mechanism, so as to reduce the temperature rise of the voice coil motor, and theoretically, the magnetic circuit structure can realize the gravity compensation function, but the voice coil motor has a smaller stroke and a more complex magnetic circuit structure, and is not suitable for a large-stroke working condition.

Therefore, a voice coil motor with a large stroke is needed at the present stage, the problems that the traditional voice coil motor with a gravity compensation function has a too small stroke and is difficult to machine and manufacture can be solved, under the same size and working condition, the high thrust density of the voice coil motor can further reduce the temperature rise of the voice coil motor and improve the motion performance of a vertical module, and meanwhile, the gravity compensation structure of the voice coil motor can generate large-stroke and small-fluctuation magnetic levitation force matched with the voice coil motor.

Disclosure of Invention

The present invention is directed to a large-stroke voice coil motor, which solves the above problems of the prior art.

In order to solve the above-mentioned problems, according to an aspect of the present invention, there is provided a voice coil motor, characterized by comprising:

central magnetic steel;

at least one end magnetic steel, which is located at least one of the two axial ends of the central magnetic steel and axially spaced from the corresponding axial end of the central magnetic steel, and the center line of the end magnetic steel is arranged to coincide with the center line of the central magnetic steel;

the coil is cylindrical and is positioned outside the central magnetic steel and is radially spaced from the central magnetic steel;

the outer magnetic ring magnetic steel is cylindrical and is positioned outside the coil and is radially spaced from the coil.

In one embodiment, the central magnetic steel is cylindrical.

In one embodiment, the end magnetic steel is cylindrical.

In one embodiment, the end magnetic steel is columnar.

In one embodiment, the magnetic coil further comprises inner magnetic ring steel, and the inner magnetic ring steel is cylindrical and is located between the central steel and the coil and is radially spaced from the central steel and the coil.

In an embodiment, the magnetization directions of the central magnetic steel and the at least one end magnetic steel are axial, the magnetization directions of the central magnetic steel and the at least one end magnetic steel are the same, and the magnetization direction of the outer magnetic ring magnetic steel is radial.

In an embodiment, the magnetization directions of the central magnetic steel and the at least one end magnetic steel are axial, the magnetization directions of the central magnetic steel and the at least one end magnetic steel are the same, the magnetization directions of the outer magnetic ring magnetic steel and the inner magnetic ring magnetic steel are radial, and the magnetization directions of the outer magnetic ring magnetic steel and the inner magnetic ring magnetic steel are the same.

In an embodiment, the device further comprises a first support and a second support, the central magnetic steel, the at least one end magnetic steel and the coil being fixed to the first support, the outer magnetic ring magnetic steel being fixed to the second support, the first support and the second support being axially translatable with respect to each other.

In an embodiment, further comprising a first bracket and a second bracket, said central magnetic steel, said at least one end magnetic steel and said coil being fixed to said first bracket, said inner magnetic ring magnetic steel and said outer magnetic ring magnetic steel being fixed to said second bracket, said first bracket and said second bracket being axially translatable with respect to each other.

In one embodiment, the first support comprises a first support base and a central support and a cylindrical coil support extending axially perpendicular to the support base, the central magnetic steel and the at least one end magnetic steel being arranged in the central support and the coil being arranged in the cylindrical coil support.

In an embodiment, the cylindrical coil support is provided with an annular channel, which is located radially inside or outside the coil.

In one embodiment, the second bracket includes a second bracket base and a cylindrical outer bracket extending in an axial direction perpendicular to the second bracket base, and the outer magnetic ring magnet steel is fixed to the cylindrical outer bracket.

In one embodiment, the second bracket comprises a second bracket base and a cylindrical inner bracket extending axially perpendicular to the second bracket base and a cylindrical outer bracket radially spaced from and external to the cylindrical inner bracket, the inner magnetic ring magnets being fixed to the cylindrical inner bracket and the outer magnetic ring magnets being fixed to the cylindrical outer bracket.

In one embodiment, two ends of the central magnetic steel are respectively provided with an end magnetic steel.

In one embodiment, at least one end of the central magnetic steel is provided with more than two end magnetic steels.

In one embodiment, the outer diameter of the end magnetic steel is not greater than the outer diameter of the central magnetic steel.

In one embodiment, the inner diameter of the end magnetic steel is not smaller than the inner diameter of the central magnetic steel.

According to a second aspect of the present invention, there is provided a voice coil motor, characterized by comprising:

central magnetic steel;

the inner magnetic ring magnetic steel is cylindrical and is positioned between the central magnetic steel and the coil and is radially spaced from the central magnetic steel and the coil;

an outer magnetically permeable cylinder that is cylindrical and located outside the coil and radially spaced apart from the coil.

In one embodiment, the central magnetic steel is cylindrical.

In one embodiment, the end magnetic steel is cylindrical.

In one embodiment, the end magnetic steel is columnar.

In an embodiment, the magnetization directions of the central magnetic steel and the at least one end magnetic steel are axial, the magnetization directions of the central magnetic steel and the at least one end magnetic steel are the same, and the magnetization direction of the inner magnetic ring magnetic steel is radial.

In an embodiment, further comprising a first bracket to which said central magnetic steel, said at least one end magnetic steel and said coil are fixed, and a second bracket to which said inner magnetic ring magnetic steel and said magnetically conductive cylinder are fixed, said first and second brackets being axially translatable relative to each other.

In one embodiment, the first support comprises a base, and a central support and a cylindrical coil support extending axially perpendicular to the base, the central magnetic steel and the at least one end magnetic steel being disposed on the central support, and the coil being disposed on the cylindrical coil support.

In one embodiment, the second support comprises a base, an inner ring cylindrical support extending axially perpendicular to the base, and an outer ring cylindrical support radially spaced apart from and external to the inner ring cylindrical support, the inner magnetic ring steel magnet is fixed to the inner ring cylindrical support, and the magnetically permeable cylinder is fixed to the outer ring cylindrical support.

The invention also provides a vertical mobile station comprising a mobile station body and a base, the mobile station comprising a voice coil motor according to the first aspect.

The invention also provides a vertical mobile station comprising a mobile station body and a base, the mobile station comprising a voice coil motor according to the second aspect.

The voice coil motor has high thrust density, can further reduce the temperature rise of the voice coil motor and improve the motion performance of the vertical module, and simultaneously, the gravity compensation structure can generate large-stroke and small-fluctuation magnetic levitation force matched with the voice coil motor.

Drawings

Fig. 1 is a schematic cross-sectional view of a voice coil motor according to a first embodiment of the present invention.

Fig. 2 is a schematic view of the magnetizing direction of the magnetic steel of the voice coil motor according to the first embodiment of the present invention.

Fig. 3 is a schematic view of magnetic lines of force of a voice coil motor according to a first embodiment of the present invention.

Fig. 4 is a waveform diagram of a thrust simulation of the voice coil motor according to the first embodiment of the present invention.

Fig. 5 is a schematic view of the magnetizing direction of the magnetic steel of the voice coil motor according to the second embodiment of the present invention.

Fig. 6 is a schematic cross-sectional view of a voice coil motor according to a third embodiment of the present invention.

Fig. 7 is a schematic view of the magnetizing direction of the magnetic steel of the voice coil motor according to the third embodiment of the present invention.

Fig. 8 is a schematic view of magnetic lines of force of a voice coil motor according to a third embodiment of the present invention.

Fig. 9 is a waveform diagram of a thrust simulation of a voice coil motor according to a third embodiment of the present invention.

Fig. 10 is a schematic cross-sectional view of a voice coil motor according to a fourth embodiment of the present invention.

Fig. 11 is a perspective view of a voice coil motor according to a fourth embodiment of the present invention.

Fig. 12(a) and 12(b) are structural modifications of the central magnetic steel and the end magnetic steel in the voice coil motor according to the present invention.

Fig. 13 is a schematic view of the magnetizing direction of the magnetic steel of the voice coil motor according to the fifth embodiment of the present invention.

Fig. 14 is a schematic diagram showing the positional relationship between the center magnetic steel and the end magnetic steel of the voice coil motor according to the present invention.

Fig. 15 is a schematic view showing another positional relationship between the center magnetic steel and the end magnetic steel of the voice coil motor according to the present invention.

Fig. 16 is a schematic diagram showing the positional relationship between the center magnetic steel and the two end magnetic steels of the voice coil motor according to the present invention.

Fig. 17 is a schematic view of another embodiment of the outer magnetic ring steel of the voice coil motor according to the present invention.

Fig. 18(a) and 18(b) are schematic views showing the magnetization direction of the outer magnetic ring steel shown in fig. 17.

Fig. 19 is a schematic diagram of a single point layout of a voice coil motor in a motion stage according to the present invention.

Fig. 20 is a schematic diagram of a three-point layout of a voice coil motor in a motion stage according to the present invention.

Figure 21 is a schematic diagram of a four-point layout of a voice coil motor in a motion stage according to the present invention.

Detailed Description

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings so that the objects, features and advantages of the invention can be more clearly understood. It should be understood that the embodiments shown in the drawings are not intended to limit the scope of the present invention, but are merely intended to illustrate the spirit of the technical solution of the present invention.

In the following description, for the purposes of illustrating various disclosed embodiments, certain specific details are set forth in order to provide a thorough understanding of the various disclosed embodiments. One skilled in the relevant art will recognize, however, that the embodiments may be practiced without one or more of the specific details. In other instances, well-known devices, structures and techniques associated with this application may not be shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

In the following description, for the purposes of clearly illustrating the structure and operation of the present invention, directional terms will be used, but terms such as "front", "rear", "left", "right", "outer", "inner", "outer", "inward", "upper", "lower", etc. should be construed as words of convenience and should not be construed as limiting terms.

The invention aims to overcome the defects of small stroke and large output thrust fluctuation of the traditional voice coil motor with the gravity compensation function, and provides the voice coil motor with the gravity compensation function, which has large stroke and small thrust fluctuation, so that the voice coil motor can be applied to equipment needing high-precision vertical motion. The voice coil motor of the present invention will be described with reference to the accompanying drawings.

Fig. 1 is a schematic sectional view of a voice coil motor 100 of the first embodiment. As shown in fig. 1, the voice coil motor 100 includes: center magnet steel 106, end magnet steels 105a and 105b, coil 104, and outer magnetic ring magnet steel 107. Center magnetic steel 106, end

magnetic steels

105a and 105b, coil 104, and outer magnetic ring magnetic steel 107 are all cylindrical and concentrically arranged. The end

magnetic steels

105a and 105b are respectively located at two axial ends of the central magnetic steel 106 and are axially spaced from the central magnetic steel 106 by a certain gap. On one hand, the gap is used for adjusting the magnetic field of the rotor, so that the distribution uniformity of the magnetic field of the rotor is higher, and the output thrust of the rotor also tends to be stable; on the other hand, the magnetic steel is convenient to fix and assemble. In the illustrated embodiment, the outer diameters of

end magnets

105a and 105b are the same as the outer diameter of center magnet 106, but it is understood that the inner diameters of

end magnets

105a and 105b are not smaller than center magnet 106. Coil 104 is located outside of central magnetic steel 106 and is radially spaced from central magnetic steel 106. An outer magnetic ring magnet 107 is located outside the coil 104 and is radially spaced from the coil 104. In the illustrated embodiment, the center magnetic steel 106, the end

magnetic steels

105a and 105b, and the coil 104 are fixed relative to the mover base 101, and may serve as a mover of the voice coil motor; and an outer magnetic ring magnet 107 is fixed to the stator base 102 and can be used as a stator of the voice coil motor. Furthermore, a certain gap δ is left between the central magnetic steel 106 and the end

magnetic steels

105a, 105b, and the gap δ is selected according to the stroke, and generally, the gap value is preferably 0.1mm to 1.0 mm.

Due to the magnetic effect of the current, the coil 104 generates a magnetic field after being electrified, thrust for enabling the rotor base 101 to axially translate relative to the stator base 102 can be generated through interaction among a rotor magnetic field of the central magnetic steel 106 serving as a rotor, rotor magnetic fields of the end

magnetic steels

105a and 105b, an armature magnetic field of the coil 104 and a stator magnetic field of the outer magnetic ring magnetic steel 107 serving as a stator, and the amplitude and the direction of the current in the coil 104 can be adjusted to adjust the amplitude of the axial thrust of the voice coil motor. The device can be implemented in a way that a stator is fixed, a rotor translates relative to the stator, or can be implemented in a way that the rotor is fixed and the stator translates relative to the rotor, or the stator and the rotor both translate along the axial direction, and only the relative positions of the stator and the rotor change along with the displacement. The gravity compensation mechanism is composed of the central magnetic steel 106, the end

magnetic steels

105a and 105b and the outer magnetic ring magnetic steel 107, and can generate vertically upward magnetic levitation force with large stroke and small fluctuation through the interaction of the stator magnetic field and the rotor magnetic field.

In the illustrated embodiment, the mover base 101 includes a mover base 101a and a substantially cylindrical portion 101c and a cylindrical portion 103 extending from the mover base 101a, and a center magnetic steel 106 and end

magnetic steels

105a and 105b are embedded in an outer circumferential surface of the substantially cylindrical portion 101 c. To facilitate the mounting of the center magnetic steel 106 and the end

magnetic steels

105a and 105b, the mover base 101 is provided with a mover bolt 101b at the bottom of the substantially cylindrical portion 101 c. The lower section of the substantially cylindrical portion 101c is indented in outer diameter with respect to the upper section, thereby forming a space for housing the center magnetic steel 106 and the end

magnetic steels

105a and 105 b. And the mover bolt 101b has a radial dimension larger than that of the lower section of the substantially cylindrical portion 101c and can be fixed to the mover base 101a by screwing. After the center magnetic steel 106 and the end magnetic steel 105a are fitted on the substantially cylindrical portion 101c, the mover bolt 101b fitted with the end magnetic steel 105b is fixed to the lower end of the substantially cylindrical portion 101c by screwing, and the end magnetic steel 105b is fixed on the outer surface of the mover bolt 101b by bonding, so that the center magnetic steel 106 and the end

magnetic steels

105a and 105b can be held on the mover base 101. The coil 104 is provided on the outer peripheral surface of the cylindrical portion 103. It should be understood, however, that the mover base 101 may be provided in other manners as long as the center magnetic steel 106 and the end

magnetic steels

105a and 105b can be coaxially fixed with respect to each other. In this embodiment, center magnet 106 and

end magnets

105a and 105b have the same outer diameter, but it is understood that center magnet 106 and

end magnets

105a and 105b can be provided in other dimensional relationships, as described below.

As also shown in fig. 1, a substantially cylindrical bracket 102 is provided on the stator base for fixing the outer magnetic ring magnetic steel 107. In the illustrated embodiment, the outer magnetic ring steel 107 is embedded in the inner circumferential surface of the cylindrical bracket 102, but it should be understood that the outer magnetic ring steel 107 may be fixed to the stator base in other manners.

Fig. 2 shows a schematic view of the magnetizing directions of the magnetic steels in the embodiment shown in fig. 1, and the directions of arrows in the figure represent the magnetizing directions of the magnetic steels. The magnetizing directions of the central magnetic steel 106 and the end

magnetic steels

105a and 105b are the same, and both are axial downward, and the magnetizing direction of the outer magnetic ring magnetic steel 107 is radial outward. It should be understood that it is also possible to arrange for the magnetization direction of central magnet steel 106 and end magnet steels 105a and 105b to be axially upward, while the magnetization direction of outer magnetic ring magnet steel 107 is radially inward. In the illustrated embodiment, the

end magnets

105a, 105b are identical in shape and size. As shown in fig. 2, the axial lengths of outer magnetic ring magnetic steel 107, center magnetic steel 106, and end

magnetic steels

105a and 105b are L_a、L_bAnd L_cThe outer diameter 1061 of the central magnetic steel and the outer diameter 1051 of the end magnetic steel are respectively formed by D_obAnd D_ocThe inner diameter 1062 of the central magnetic steel and the inner diameter 1052 of the end magnetic steel are respectively expressed by D_bAnd D_cIndicating that the single-sided air gap between the central magnet 106 and the coil 104 is represented by R_gAnd (4) showing. Radial thickness of coil 104 is defined by W_dAnd (4) showing. Axial length L of center magnetic steel 106 and end

magnetic steels

105a and 105b_bAnd L_cUnequal, usually L_b＞L_c。

As shown in fig. 2, the radial thickness of the end

magnetic steels

105a, 105b is smaller than the radial thickness of the center magnetic steel 106. Specifically, center magnet steel outer diameter 1061 is equal to axial end magnet steel outer diameter 1051, and center magnet steel inner diameter 1062 is unequal to axial end magnet steel inner diameter 1052. It should be understood, however, that the radial positional relationship of the

end magnets

105a, 105b to the center magnet 106 may also be set such that: of end magnets 105a, 105bThe outer diameter may be slightly larger than the outer diameter of the central magnetic steel 106 or slightly smaller than the outer diameter of the central magnetic steel 106. The inner diameters of the end

magnetic steels

105a and 105b may be slightly larger than the inner diameter of the central magnetic steel 106, or slightly smaller than the inner diameter of the central magnetic steel 106. Preferably, the outer diameter of end

magnetic steels

105a, 105b is not greater than the outer diameter of center magnetic steel 106, the inner diameter of end

magnetic steels

105a, 105b is not less than the inner diameter of center magnetic steel 106, and end

magnetic steels

105a, 105b are identical to each other. The radial position relationship thereof generally has three schemes: (1) as shown in fig. 2, the outer diameter 1061 of the central magnetic steel is equal to the outer diameter 1051 of the end magnetic steel, and the inner diameter 1062 of the central magnetic steel is different from the inner diameter 1052 of the end magnetic steel; (2) as shown in fig. 15, the outer diameter 1061 of the central magnetic steel is different from the outer diameter 1051 of the end magnetic steel, and the inner diameter 1052 of the central magnetic steel is equal to the inner diameter 1062 of the end magnetic steel; (3) as shown in FIG. 14, center magnet steel outer diameter 1061 (D)_ob) Inner diameter 1062 (D)_b) Outer diameter 1051 of end magnetic steel_oc) Inner diameter 1052 (D)_c) All the same, but the distance difference between the inner diameters of the central magnetic steel 106 and the end magnetic steels 105a, 105b is equal to the distance difference between the outer diameters of the central magnetic steel 106 and the end magnetic steels 105a, 105b, and the radial thickness of the central magnetic steel 106 is greater than that of the end magnetic steels 105a, 105b, that is, the cylinder surface of the cylinder of the central magnetic steel 106, which is bisected along the radial direction, coincides with the cylinder surface of the cylinder of the end magnetic steel, which is bisected along the radial direction, that is, D_b+(D_ob-D_b)/2＝D_c+(D_oc-D_c)/2。

Furthermore, it is to be understood that the

end magnets

105a, 105b may also be different from each other, for example one or more of their outer diameter, inner diameter, barrel thickness or height may be different from each other. In the embodiment of fig. 2, three sets of size ratios are defined: lambda [ alpha ]₁＝L_a/L_b、λ₂＝L_c/L_b、γ₁＝D_b/D_cThe size ratio determines the amplitude of the large-stroke gravity compensation structure and also influences the fluctuation of the magnetic levitation force of the gravity compensation structure, and generally the sizes are changed along with the change of the stroke and the amplitude of the voice coil motor. Wherein, assuming that the total stroke of the voice coil motor is S, the value range of λ 1 is preferably [1/4,1+2 λ₂-S/L_b]；λ₂Value of and the number of blocks N of the axial end magnetic steel_t(as described below) when N_tWhen 1, λ₂Preferably in the value range of [1/4, 3/8 ]](ii) a Generally, gamma₁The value of (a) is related to the fluctuation of the magnetic levitation force, and the gamma is determined by considering the processing difficulty and the assembly process of the magnetic steel₁Preferably in the value range of [1/8, 1 ]]. In addition, a single-sided air gap R between coil 104 and central magnet 106_gThe strength of the magnetic field is also influenced to a certain extent, so that the amplitude and fluctuation degree of the magnetic suspension force provided by the voice coil motor are further influenced, and under the general condition, the single-side air gap R_gThe value of (A) is changed along with the change of the magnetic suspension force amplitude, and a single-side air gap R_gIs preferably R_g≥20δ。

Fig. 3 shows a schematic diagram of magnetic lines of force of the voice coil motor 100. According to the distribution track of magnetic lines of force and the principle that like poles repel each other, it can be inferred that after the coil 104 is electrified, the central magnetic steel 106, the end

magnetic steels

105a and 105b fixed to the rotor base and the radial thrust generated by the coil 104 to the outer magnetic ring magnetic steel 107 are a group of forces with equal amplitude and uniformly distributed along the circumference, so that the resultant force of the radial disturbance forces borne by the rotor base is zero, and the rotor base can be always kept in the center of the voice coil motor. The interaction among the central magnetic steel 106, the end

magnetic steels

105a and 105b, and the outer magnetic ring magnetic steel 107 compensates the gravity of the mover base 101 and its load, the central magnetic steel 106, and the end

magnetic steels

105a and 105 b. The interaction between the coil 104 and the outer magnetic ring magnetic steel 107 can push the rotor base 101 to axially translate, and the amplitude and the direction of current in the coil can be adjusted to adjust the amplitude of vertical thrust of the voice coil motor. Through electromagnetic simulation, the axial thrust of the voice coil motor, the axial thrust of the gravity compensation structure and the curve of the thrust which can be provided by the whole device can be obtained, as shown in fig. 4, in a stroke range of 25mm, the amplitude of the axial thrust of the voice coil motor is about 40N, the amplitude of the axial thrust of the gravity compensation structure is about 80N, and the amplitude of the axial thrust which can be provided by the whole device is about 120N, wherein the fluctuation of the thrust of the whole device is about 1.5%, and is basically close to the fluctuation degree of the traditional voice coil motor with the gravity compensation structure in a stroke range of +/-2 mm.

Fig. 4 shows a waveform diagram of a thrust simulation of the voice coil motor 100. The figure shows the variation of the thrust force with the vertical displacement of the voice coil motor. As can be seen, the voice coil motor thrust remains substantially smooth as the stroke changes. According to the distribution track of magnetic force lines and the principle that like poles repel each other, the weight of the rotor can be deduced to be compensated by magnetic suspension force generated by the interaction of the rotor magnetic field and the stator magnetic field of the gravity compensation mechanism, the axial thrust of the voice coil motor can be changed by adjusting the amplitude and the direction of current led into the coil, and the radial thrust generated by the gravity compensation structure is a group of forces with equal amplitude and uniformly distributed along the circumference, so that the rotor is always concentric with the stator, and the uniform circumferential air gap of the coil in the voice coil motor is further ensured.

A schematic cross-sectional view of a voice coil motor 300 according to a second embodiment of the present invention is shown in fig. 5. The voice coil motor 300 of this embodiment includes a center magnetic steel 306, an end magnetic steel 305, a coil 304, and an outer magnetic ring magnetic steel 307. Center magnet steel 306, end magnet steel 305, coil 304, and outer magnetic ring magnet steel 307 are all cylindrical structures, end magnet steel 305 is located at one axial end of center magnet steel 306, coil 304 is located outside center magnet steel 306 and radially spaced from center magnet steel 306, and outer magnetic ring magnet steel 307 is located outside coil 304 and radially spaced from it. The magnetizing directions of the central magnetic steel 306 and the end magnetic steel 305 are the same and are downward along the axial direction, and the magnetizing direction of the outer magnetic ring magnetic steel 307 is outward in the radial direction. It should be understood, however, that the magnetization direction of center magnet steel 306 and end magnet steel 305 may be set axially upward, and outer magnetic ring magnet steel 307 may be set radially inward. In this embodiment, the voice coil motor provides a smooth thrust only in the sections I and II in the stroke range. Under the condition that the motion states of the sections III and IV are not influenced by the fluctuation of the thrust, the voice coil motor with the structure can be adopted.

Fig. 6 shows a schematic cross-sectional view of a voice coil motor 400 according to a third embodiment of the present invention. The voice coil motor 400 of this embodiment includes a center magnetic steel 402, end

magnetic steels

401a and 401b, an inner magnetic ring magnetic steel 404, a coil 407, and an outer magnetic ring magnetic steel 405. The central magnetic steel 402, the end

magnetic steels

401a and 401b, the inner magnetic ring magnetic steel 404, the coil 407, and the outer magnetic ring magnetic steel 405 are all cylindrical structures and are concentrically arranged, and the end

magnetic steels

401a and 401b are respectively located at two axial ends of the central magnetic steel 402 and are axially spaced from the central magnetic steel 402 by a certain gap. The gap is used for adjusting the magnetic field of the rotor. The inner magnetic ring magnet steel 404 is located outside the center magnet steel 402 and radially spaced apart from the center magnet steel 402, the coil 407 is located outside the inner magnetic ring magnet steel 404 and radially spaced apart from the inner magnetic ring magnet steel 404, and the outer magnetic ring magnet steel 405 is located outside the coil 407 and radially spaced apart from the coil 407.

In the illustrated embodiment, the outer diameters of

end magnets

401a and 401b are the same as the outer diameter of center magnet 402, but it is understood that the two may be provided in other dimensional relationships, as described below. In the illustrated embodiment, center magnet 402,

end magnets

401a and 401b, and coil 407 are fixed relative to stator base 403, which may serve as the stator of a voice coil motor; and an inner magnetic ring magnet 404 and an outer magnetic ring magnet 405 are fixed to a mover base 406, which may be used as a mover of the voice coil motor. In addition, the axial ends of the end

magnetic steels

401a and 401b and the central magnetic steel 402 are separated by a certain gap δ, and the gap value δ is selected according to the stroke, and generally, the gap value is preferably 0.1mm to 1.0 mm.

Due to the magnetic effect of the current, the coil 407 generates a magnetic field after being electrified, thrust for enabling the rotor base 406 to axially translate relative to the stator base 403 can be generated through interaction among the stator magnetic field of the center magnetic steel 402 serving as the stator, the stator magnetic fields of the end

magnetic steels

401a and 401b, the armature magnetic field of the coil 407 and the rotor magnetic field of the inner magnetic ring magnetic steel 404 and the outer magnetic ring magnetic steel 405 serving as the rotor, and the amplitude and the direction of the current in the coil 407 can be adjusted to adjust the amplitude of the axial thrust of the voice coil motor. The device can be implemented in such a way that the stator is fixed, the rotor moves relative to the stator, or the device can be implemented in such a way that the rotor is fixed and the stator moves relative to the rotor, or the stator and the rotor both move in an axial direction, and only the relative positions of the stator and the rotor change along with the displacement. The gravity compensation mechanism is composed of central magnetic steel 402, end magnetic steel 401, inner magnetic ring magnetic steel 404 and outer magnetic ring magnetic steel 405, and can generate vertically upward magnetic levitation force with large stroke and small fluctuation through the interaction of a stator magnetic field and a rotor magnetic field.

In the illustrated embodiment, the mover base 406 includes a mover base 406a and a cylindrical inner support 406c and a cylindrical outer support 406d extending downward from the mover base 406a, wherein the cylindrical outer support 406d is disposed radially outward of the cylindrical inner support 406 c. The inner magnetic ring magnetic steel 404 and the outer magnetic ring magnetic steel 405 are provided to the cylindrical inner holder 406c and the cylindrical outer holder 406d, respectively. The stator base 403 includes a stator base 403a, and a center support 403b and a cylindrical coil support 403c extending upward from the stator base 403a, the center support 403b being generally cylindrical and the cylindrical coil support 403c being disposed around the center support 403 b. Center magnetic steel 402 and end

magnetic steels

401a and 401b are provided on the outer peripheral surface of center bracket 403 b. And the coil 407 is embedded in the outer peripheral surface of the cylindrical coil support 403 c. It should be understood, however, that the central magnetic steel 402 and the end

magnetic steels

401a and 401b and the coil 407 may be provided to the stator base 403 in other ways as long as they are ensured to be coaxially arranged and satisfy the above-mentioned radial and axial relationships. In this embodiment, center magnet steel 402 and end magnet steels 401a and 401b have the same outer diameter, but it should be understood that center magnet steel 402 and end magnet steels 401a and 401b may be provided in other dimensional relationships, as described below.

Fig. 7 shows the magnetizing direction and the dimension of the magnetic steel of the voice coil motor 400 according to the third embodiment of the present invention. In the illustrated embodiment, the magnetization directions of central magnetic steel 402 and end

magnetic steels

401a and 401b are the same and both are axially downward, and the magnetization directions of inner magnetic ring magnetic steel 404 and outer magnetic ring magnetic steel 405 are the same and both are radially outward. However, it should be understood that the magnetization directions of the central magnetic steel 402 and the end

magnetic steels

401a and 401b may be set to be axially upward, and the magnetization directions of the inner magnetic ring magnetic steel 404 and the outer magnetic ring magnetic steel 405 are both radially inward. In addition, as can be seen from the figure, the axial lengths of the outer magnetic ring magnetic steel 404 and the inner magnetic ring magnetic steel 405 are equal, and are L_aRepresents; the axial lengths of the center magnetic steel 402, the end

magnetic steels

401a and 401b, and the coil 407 are L, respectively_b、L_c、L_cAnd L_dThe radial thickness of the stator coil 407 is W_dThe outer diameter of the central magnetic steel 4021 and the outer diameter of the stator end magnetic steel 4011 are respectively represented by D_obAnd D_ocThe inner diameter of the central magnetic steel 4022 and the inner diameter of the stator end magnetic steel 4012 are respectively expressed by D_bAnd D_cAnd (4) showing. Axial length L of center magnet steel 402 and stator end magnet steel 401_bAnd L_cUnequal, radial position of which is offThere are three schemes: (1) the outer diameter 4021 of the central magnetic steel is equal to the outer diameter 4011 of the magnetic steel at the end part of the stator, and the inner diameters 4022 and 4012 are different; (2) the outer diameter 4021 of the central magnetic steel is not equal to the outer diameter 4011 of the magnetic steel at the end part of the stator, and the inner diameters 4022 and 4012 are equal; (3) the outer diameter 4021 and the inner diameter 4022 of the central magnetic steel are different from the outer diameter 4011 and the inner diameter 4012 of the stator end magnetic steel, but the distance difference between the inner diameters of the central magnetic steel 402 and the end magnetic steels 401a and 401b is equal to the distance difference between the outer diameters of the central magnetic steel 402 and the end magnetic steels 401a and 401b, and the radial thickness of the central magnetic steel 402 is greater than the radial thicknesses of the end magnetic steels 401a and 401b, i.e., the radial thickness of the cylinder of the central magnetic steel 402 is superposed with the radial thickness of the cylinder of the end magnetic steel along the radial direction, i.e., D_b+(D_ob-D_b)/2＝D_c+(D_oc-D_c)/2. In the particular embodiment shown, center magnet steel outer diameter 4021 is equal to stator end magnet steel outer diameter 4011, and

inner diameters

4022 and 4012 are unequal.

In this embodiment, three sets of size ratios are defined: lambda [ alpha ]₁＝L_a/L_b、λ₂＝L_c/L_b、γ₁＝D_b/D_cThe size ratio determines the output force amplitude of the voice coil motor with the gravity compensation function and also influences the fluctuation size of the magnetic suspension force of the gravity compensation structure, and the sizes generally change along with the stroke and the amplitude of the gravity compensation structure. λ if assuming the total stroke of the voice coil motor to be S₁Preferably in the value range of [1/4,1+2 λ₂-S/L_b]；λ₂The value of (A) and the number N of the magnetic steel at the end part of one side_tCorrelation when N is_tWhen 1, λ₂Preferably in the value range of [1/4, 3/8 ]](ii) a Generally, gamma₁The value of (a) is related to the fluctuation of the magnetic levitation force, and gamma is taken into consideration of the processing difficulty and the assembly process of the magnetic steel₁Preferably in the value range of [1/8, 1 ]]。

Fig. 8 shows a schematic diagram of magnetic lines of force of the voice coil motor 400 of fig. 6, and according to the distribution track of the magnetic lines of force and the principle that like poles repel each other, it can be inferred that the weight of the mover can be compensated by the gravity compensation acting force generated by the magnetic fields of the mover and the stator, and the amplitude and direction of the current in the coil 407 can be adjusted to adjust the amplitude of the thrust of the voice coil motor, and thus the actual output force thereof. Because the radial disturbance force generated by the gravity compensation structure is a group of forces with equal amplitude and uniformly distributed along the circumference in the direction, the rotor magnetic steel can be concentric with the stator magnetic steel all the time, and further the uniform circumferential air gap of the coil in the voice coil motor is ensured. Generally, the thrust constant of the voice coil motor is proportional to the normal component of the magnetic flux passing through the cross section of the coil 407, while the continuous thrust of the voice coil motor can be generally calculated from the thrust constant, and the thrust density is proportional to the continuous thrust of the voice coil motor at the same temperature, inversely proportional to the volume of the voice coil motor, and on the premise that the outer diameter and the axial length are equal, the larger the continuous thrust of the voice coil motor is, the larger the thrust density is.

Through electromagnetic simulation, a curve of the axial thrust of the voice coil motor, the axial thrust of the gravity compensation structure and the output resultant force of the voice coil motor can be obtained, as shown in fig. 9, in a stroke range of 15mm, the amplitude of the output thrust of the voice coil motor is about 9.0N, the amplitude of the gravity compensation acting force of the gravity compensation structure is about 40.0N, and the amplitude of the axial resultant force of the voice coil motor is about 59.0N, wherein the fluctuation of the thrust of the whole device is about 1.75%, and is basically close to the fluctuation degree of the traditional voice coil motor with the gravity compensation structure in a stroke range of +/-2 mm. In addition, when the temperature rises equally, the thrust density of the voice coil motor in the embodiment is 1-1.5 times that of the existing voice coil motor.

Fig. 10 shows a schematic cross-sectional view of a voice coil motor 500 according to a fourth embodiment of the present invention. This embodiment is substantially the same as voice coil motor 400 except that the coil-provided support is also provided with an annular channel for cooling for the passage of a cooling medium such as water. Specifically, the voice coil motor 500 of this embodiment includes a center magnetic steel 502, end

magnetic steels

501a and 501b, an inner magnetic ring magnetic steel 504, a coil 507, and an outer magnetic ring magnetic steel 505. Center magnetic steel 502, end

magnetic steels

501a and 501b, inner magnetic ring magnetic steel 504, coil 507, and outer magnetic ring magnetic steel 505 are all cylindrical structures and concentrically arranged, and end

magnetic steels

501a and 501b are respectively located at two axial ends of center magnetic steel 502 and axially spaced from center magnetic steel 502 by a certain gap. Inner magnetic ring magnet steel 504 is located outside center magnet steel 502 and radially spaced from center magnet steel 502, coil 507 is located outside inner magnetic ring magnet steel 504 and radially spaced therefrom, and outer magnetic ring magnet steel 505 is located outside coil 507 and radially spaced therefrom. The inner magnetic ring magnetic steel 504 and the outer magnetic ring magnetic steel 505 are respectively fixed to the mover base 503, and the structure of the mover base 503 is the same as that of the mover base 403, which is not described in detail. The stator base 506 includes a stator base 506a, and a substantially cylindrical portion 506b extending upward from the stator base 506a and a cylindrical portion 506c disposed therearound. Center magnetic steel 502 and end

magnetic steels

501a and 501b are provided on the outer peripheral surface of substantially cylindrical portion 506 b. And a coil 507 is embedded in the outer peripheral side surface of the cylindrical portion 506 c. It should be understood, however, that the central magnetic steel 502 and the end

magnetic steels

501a and 501b and the coil 507 may be provided to the stator base 503 in other ways as long as their concentric axial arrangement is ensured and the above-described radial and axial relationships are satisfied. In this embodiment, a cylindrical portion 506c constitutes a bobbin that supports the coil 507, and a cooling water passage 5081 is provided in the cylindrical portion 506c on the radially inner side of the coil 507. When the output thrust density of the voice coil motor 500 is increased, the cooling water channel 5081 is arranged to cool the temperature rise generated by the coil 507, so that the amplitude of the continuous current in the coil 507 can be increased, and the output thrust and the thrust density of the voice coil motor can be further increased under the condition that the thrust constant is not changed. It should be noted that the channel width and depth of the cooling channel 5081 are determined by rigorous fluid-solid coupling simulations.

A perspective view of the voice coil motor 500 of this embodiment is shown in fig. 11. As can be seen from fig. 11, a water inlet end connector 5082 and a water outlet end connector 5083 for cooling water are added to the bottom of the coil support formed by the cylindrical portion 506c, and the water inlet end connector 5082 and the water outlet end connector 5083 are respectively connected to the water path of the cooling water tank, thereby forming a water cooling system of the voice coil motor. The water cooling system of the voice coil motor can take away a large amount of heat generated by the stator coil 507, so that the output thrust density of the voice coil motor is improved.

Fig. 12(a) and 12(b) show modifications of the center magnetic steel and the end magnetic steel of each voice coil motor in the present invention. In fig. 12(a), the center magnetic steel is cylindrical and the end magnetic steel is cylindrical, and its outer diameter 6021 is equal to the outer diameter 6011 of the end magnetic steel. In fig. 12(b), the center magnet is cylindrical and the end magnet is cylindrical, and the outer diameter 6012 of the end magnet is equal to the outer diameter 6022 of the center magnet. The above two variations are applicable to all embodiments of the voice coil motor according to the present invention.

Fig. 13 shows a modification of the

voice coil motors

400 and 500 according to the third and fourth embodiments of the present invention. The magnetic steel structure of the voice coil motor 700 of this modification is the same as that of the

voice coil motors

400 and 500 except that the outer magnetic ring magnet steel is replaced with a magnetic conductive cylinder 705, and the magnetic conductive cylinder 705 is processed from a material having a high magnetic conductivity. Specifically, voice coil motor 700 includes center magnet steel 702, end magnet steels 701a and 701b, inner ring magnet steel 704, coil 707, and magnetically conductive cylinder 705. The central magnetic steel 702, the end

magnetic steels

701a and 701b, the inner magnetic ring magnetic steel 704, the coil 707, and the magnetic conductive cylinder 705 are coaxially arranged, and the end

magnetic steels

701a and 701b are respectively located at two axial ends of the central magnetic steel 702 and axially spaced from the central magnetic steel 702 by a certain gap. The inner magnetic ring magnet 704 is located outside the central magnet 702 and radially spaced from the central magnet 702, the coil 707 is located outside the inner magnetic ring magnet 704 and radially spaced therefrom, and the magnetically permeable cylinder 705 is located outside the coil 707 and radially spaced therefrom. According to application requirements of different working conditions, the difficulty degree of a magnetic steel bonding process is considered, the magnetic conduction cylinder 705 can be used for replacing the outer magnetic ring magnetic steel, the axial length 7051 of the magnetic conduction cylinder 705 is equal to that of the inner magnetic ring magnetic steel 704, and the output thrust density of the voice coil motor 700 is higher than that of a traditional voice coil motor.

Fig. 14-16 show different variations of the central magnetic steel and the end magnetic steel of the voice coil motor according to the present invention. These variations apply to all embodiments of the invention. In fig. 14, the outer diameter and the inner diameter of the central magnetic steel are different from the outer diameter and the inner diameter of the end magnetic steel, but the distance difference between the inner diameters of the central magnetic steel and the end magnetic steel is equal to the distance difference between the outer diameters of the central magnetic steel and the end magnetic steel, and the radial thickness of the central magnetic steel is greater than the radial thickness of the end magnetic steel, that is, the radial thickness of the cylinder of the central magnetic steel is coincident with the radial thickness of the end magnetic steel, that is, D_b+(D_ob-D_b)/2＝D_c+(D_oc-D_c)/2. In the context of figure 15 of the drawings,the outer diameter of the central magnetic steel is not equal to that of the end magnetic steel, and the inner diameter of the central magnetic steel is equal to that of the end magnetic steel. In fig. 16, the outer diameter of the center magnetic steel is equal to the outer diameter of the end magnetic steel, and the inner diameter of the center magnetic steel is different from the inner diameter of the end magnetic steel. Fig. 16 also shows that two end magnets are provided at one axial end of the central magnet in axial alignment. It should be understood that two end magnets aligned axially may be provided at both axial ends of the central magnet. It should be understood that the axial end unilateral division number N of the end magnetic steel_tThe gravity compensation structure is not limited to 1, and can be larger than 1 and can be adjusted according to the stroke of the gravity compensation structure required by the voice coil motor. Generally, the unilateral block number N of the end magnetic steel_tThe more, the more even the distribution of the magnetic field provided by the center and end magnetic steels is, and the smaller the fluctuation of the gravity compensation acting force amplitude provided by the gravity compensation structure is. In the embodiment shown in fig. 16, the number of blocks N of the end portion magnetic steel is given_t2. It is to be understood, however, that N_tMay be made larger as desired.

Fig. 17 is a plan view showing another embodiment of the outer magnetic ring steel of the voice coil motor according to the present invention. In consideration of the difficulty of magnetizing the outer magnetic ring steel magnet and the processing technology, the outer magnetic ring steel magnet in each of the above embodiments may be replaced with a group of radial magnetizing steel magnets partitioned along the circumferential direction, and as shown in the figure, the outer magnetic ring steel magnet is composed of eight partitioned

steel magnets

701a, 701b, 701c, 701d, 701e, 701f, 701g, and 701h partitioned along the circumferential direction. In order to eliminate the radial unbalanced force of each block magnetic steel, the number N of the blocks of the outer magnetic ring magnetic steel is usually an even number, and N is 8 in this embodiment. However, it should be understood that the value of N is not limited to the value in this embodiment, and may also be expanded to other even numbers, for example, 4, 6, 10, etc., according to the inner and outer diameters of the outer magnetic ring magnetic steel.

In the embodiment shown in fig. 17, the magnetization direction of each block of magnetic steel may be radial magnetization or parallel magnetization, as shown in fig. 18(a) and 18 (b). Fig. 18(a) shows a schematic view of radial magnetization of the block magnetic steel, where the magnetization directions of the respective positions of the block magnetic steel are all radially outward. FIG. 18(b) shows a schematic diagram of parallel magnetization of the block magnetic steels, wherein the magnetization directions of the respective positions of the block magnetic steels are all parallel to the radial direction of the circumferential center bisecting plane of the block magnetic steels and the magnetization directions are outward

Fig. 19-21 show bottom views of a table using a voice coil motor according to the present invention. A cavity is provided below the table for receiving the voice coil motor according to the present invention. Wherein the cavity below the table may be one, as shown in fig. 19; three in, for example, a regular triangle arrangement to form a three-point layout, as shown in fig. 20; or four in a square arrangement to form a four-point layout, as shown in fig. 21.

While the preferred embodiments of the present invention have been described in detail above, it should be understood that aspects of the embodiments can be modified, if necessary, to employ aspects, features and concepts of the various patents, applications and publications to provide yet further embodiments.

These and other changes can be made to the embodiments in light of the above detailed description. In general, in the claims, the terms used should not be construed to be limited to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled.

Claims

1. A voice coil motor, comprising:

central magnetic steel;

2. The voice coil motor of claim 1, wherein the central magnetic steel is cylindrical.

3. The voice coil motor of claim 1, wherein the central magnetic steel is cylindrical.

4. A voice coil motor as claimed in claim 2 or 3, wherein the end magnetic steel is cylindrical.

5. A voice coil motor as claimed in claim 2 or 3, wherein the end magnetic steel is cylindrical.

6. The voice coil motor of claim 1, further comprising an inner magnetic ring magnet steel, the inner magnetic ring magnet steel being cylindrical and located between and radially spaced from the central magnet steel and the coil.

7. The voice coil motor of claim 1, wherein the magnetization directions of the central magnetic steel and the at least one end magnetic steel are axial, the magnetization directions of the central magnetic steel and the at least one end magnetic steel are the same, and the magnetization direction of the outer magnetic ring magnetic steel is radial.

8. The voice coil motor of claim 6, wherein the magnetization directions of the central magnetic steel and the at least one end magnetic steel are axial, the magnetization directions of the central magnetic steel and the at least one end magnetic steel are the same, the magnetization directions of the outer magnetic ring magnetic steel and the inner magnetic ring magnetic steel are radial, and the magnetization directions of the outer magnetic ring magnetic steel and the inner magnetic ring magnetic steel are the same.

9. The voice coil motor of claim 1, further comprising a first mount and a second mount, the center magnetic steel, the at least one end magnetic steel, and the coil being secured to the first mount, the outer magnetic ring magnetic steel being secured to the second mount, the first mount and the second mount being axially translatable relative to each other.

10. The voice coil motor of claim 6, further comprising a first bracket and a second bracket, the center magnet steel, the at least one end magnet steel, and the coil being secured to the first bracket, the inner and outer magnetic ring magnets being secured to the second bracket, the first and second brackets being axially translatable relative to each other.

11. A voice coil motor as claimed in claim 9 or 10, wherein the first support comprises a first support base and a central support and a cylindrical coil support extending axially perpendicular to the support base, the central magnetic steel and the at least one end magnetic steel being provided at the central support and the coil being provided at the cylindrical coil support.

12. The voice coil motor of claim 11, wherein the cylindrical coil support is provided with an annular channel located radially inside or outside the coil.

13. The voice coil motor of claim 9 or 10, wherein the second yoke includes a second yoke base and a cylindrical outer yoke extending axially perpendicular to the second yoke base, the outer magnetic ring steel being fixed to the cylindrical outer yoke.

14. The voice coil motor of claim 10, wherein the second spider comprises a second spider base and a cylindrical inner spider extending axially perpendicular to the second spider base and a cylindrical outer spider radially spaced from and external to the cylindrical inner spider, the inner magnetic ring magnets being fixed to the cylindrical inner spider and the outer magnetic ring magnets being fixed to the cylindrical outer spider.

15. The voice coil motor of claim 1, wherein one end magnetic steel is provided at each end of the central magnetic steel.

16. The voice coil motor of claim 1, wherein at least one end of the central magnetic steel is provided with more than two end magnetic steels.

17. The voice coil motor of claim 4, wherein an outer diameter of the end magnetic steel is not greater than an outer diameter of the center magnetic steel.

18. The voice coil motor of claim 4, wherein an inner diameter of the end magnetic steel is not smaller than an inner diameter of the center magnetic steel.

19. A voice coil motor, comprising:

central magnetic steel;

20. The voice coil motor of claim 19, wherein the central magnetic steel is cylindrical.

21. The voice coil motor of claim 19, wherein the central magnetic steel is cylindrical.

22. A voice coil motor as claimed in claim 20 or 21, wherein the end magnetic steel is cylindrical.

23. The voice coil motor of claim 20, wherein the end magnetic steel is cylindrical.

24. The voice coil motor of claim 19, wherein the magnetization directions of the central magnetic steel and the at least one end magnetic steel are axial, the magnetization directions of the central magnetic steel and the at least one end magnetic steel are the same, and the magnetization direction of the inner magnetic ring magnetic steel is radial.

25. The voice coil motor of claim 19, further comprising a first bracket and a second bracket, the center magnet steel, the at least one end magnet steel, and the coil being fixed to the first bracket, the inner ring magnet steel and the magnetically permeable cylinder being fixed to the second bracket, the first and second brackets being axially translatable relative to each other.

26. The voice coil motor of claim 19, wherein the first support comprises a base and a center support and a cylindrical coil support extending axially perpendicular to the base, the center magnetic steel and the at least one end magnetic steel being disposed on the center support, and the coil being disposed on the cylindrical coil support.

27. The voice coil motor of claim 26, wherein the cylindrical coil support is provided with an annular channel, the annular channel being located radially inside or outside the coil.

28. The voice coil motor of claim 25, wherein the second support comprises a base and an inner ring cylindrical support extending axially perpendicular to the base and an outer ring cylindrical support radially spaced apart from and external to the inner ring cylindrical support, the inner magnetic ring steel being fixed to the inner ring cylindrical support and the magnetically permeable cylinder being fixed to the outer ring cylindrical support.

29. The voice coil motor of claim 19, wherein one end magnetic steel is provided at each end of the central magnetic steel.

30. The voice coil motor of claim 19, wherein at least one end of the central magnetic steel is provided with more than two end magnetic steels.

31. The voice coil motor of claim 22, wherein an outer diameter of the end magnetic steel is not greater than an outer diameter of the center magnetic steel.

32. The voice coil motor of claim 22, wherein an inner diameter of the end magnetic steel is not smaller than an inner diameter of the center magnetic steel.

33. A vertical mobile station comprising a mobile station body and a base, the mobile station comprising a voice coil motor according to any of claims 1-18.

34. A vertical mobile station comprising a mobile station body and a base, the mobile station comprising a voice coil motor according to any of claims 19-32.