JPH05328696A - Movable coil type actuator - Google Patents

Abstract

PURPOSE:To smoothly move a moving element and to alleviate power necessary to move the element by operating propulsion forces of a plurality of movable coil type actuators substantially at a center of gravity of the element and a movable element made of a moving member. CONSTITUTION:A moving element 12 is supported movably in a direction parallel to an optical axis of a lens 7 in a state that two positions of opposite side are respectively supported two guide shafts 17, 17' through its center. When driving currents flow to movable coils 31, 31', propulsion forces are applied to the coils 31, 31' in a direction responsive to a direction of the current in a direction along its axial direction, and hence the element 12 is moved forward or rearward together with the movable lens 7 by the propulsion force. Since the forces are operated from a center of gravity of a movable element formed of the element 12 and the lens 7 to two positions spaced at equal distances in opposite directions, a resultant force of the two propulsion forces is applied to a position of the center of gravity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel moving coil type actuator device. More specifically, the present invention relates to a movable coil type actuator device in which a guide shaft that movably supports a movable body is configured as an inner yoke, and the movable body can be moved smoothly, which reduces power consumption. It is an object of the present invention to provide a new moving coil type actuator device that can be completed.

[0002]

2. Description of the Related Art A moving coil type moving member is used as one of driving means for moving a moving member that is moved in a linear direction, such as a movable lens in a lens system of a camera or a recording / reproducing head in a disk type recording / reproducing apparatus. There is an actuator device.

In such a movable coil type actuator device, a movable body holding a movable member supports the movable coil, and the movable coil is movably arranged in a magnetic field formed by a yoke and a magnet. Is supplied to apply a propulsive force to the movable coil, and the movable body is moved by the propulsive force.

By the way, as one of the moving coil type actuator devices of this type, it has a function as an inner yoke which is one of the elements for forming the magnetic field on the guide shaft for movably supporting the moving body. A structure has been proposed in which miniaturization is realized by carrying it.

FIG. 5 shows an example of a moving coil type actuator device having such a structure, which was filed by the present applicant in Japanese Patent Application No. 2-135993.

In the figure, reference numeral b denotes a moving body, which is a cylindrical lens holding portion d holding a movable lens c, and a lens holding portion d projecting from a part of the outer peripheral surface of the lens holding portion d and separated from each other in the axial direction. Two coil holding parts e, e that form a ring shape
And a leg portion f projecting from a position substantially opposite to the formation position of the coil holding portions e, e with the movable lens c sandwiched therebetween.

Reference numeral g is a movable coil whose both ends in the axial direction are held by the coil holding portions e, e. The movable coil g is wound around a cylindrical coil bobbin spanned between the coil holding parts e and e.

[0008] h is a cylindrical main guide axis that also serves as an inner yoke, i is parallel to the main guide axis h, and the movable lens c
It is an auxiliary guide shaft which is arranged at a position on the opposite side with respect to.

J, j are bearings fitted in the coil holding parts e, e through a part of the coil bobbin, and the main guide shaft h is slidably inserted in the holes of the bearings j, j. Has been done.

K is a notch formed in the leg portion f,
The notch k is slidably engaged with the auxiliary guide shaft i.

As a result, the movable body b is supported by the main guide axis h and the auxiliary guide axis i so as to be movable in the direction parallel to the optical axis of the movable lens c.

Reference numeral 1 denotes an outer yoke having a substantially cylindrical shape, and a notch m extending in the axial direction is formed in a part in the circumferential direction, and surrounds the moving range of the movable coil g coaxially with the main guide axis h. The movable coil g is positioned in the outer yoke l.

Reference numerals n and n are magnets each having a thick disk shape with holes o formed in the center thereof and magnetized so that the central portion and the outer peripheral portion have different polarities. Notches p, p are formed in a part, and the notches p, p are the outer yoke l.
The main guide shaft h is inserted through the holes o, o in a direction coinciding with the notch m, and the outer peripheral surface thereof is in contact with the inner surface of the outer yoke l.

The magnetic fluxes emitted from the magnets n and n are referred to as an outer yoke l-an annular space q defined by the outer yoke l and the main guide shaft h-the main guide shaft h-the magnets n and n. A magnetic field is formed through the magnetic path, and the movable coil g is located in this magnetic field.

When a driving current is supplied to the movable coil g, a propulsive force in the axial direction is applied to the movable coil g, and the movable body b is moved in the axial direction by this propulsive force.

[0016]

However, in such a movable coil type actuator device a, the position of the center of gravity of the moving body b including the action point of the propulsive force applied to the movable coil g and the movable lens c. Therefore, a part of the applied propulsive force acts as a force for rotating the moving body b with the substantially center of gravity position as the fulcrum of rotation, and as a result, the bearings j, j are moved by the main guides. There is a problem in that the movement of the moving body b is smooth and disappears because it bites on the axis h.

Further, since the movement of the moving body b is not smooth, a predetermined propulsive force cannot be obtained unless electric power more than necessary is supplied to the movable coil, and therefore power consumption increases. It was

[0018]

In order to solve the above-mentioned problems, the moving coil type actuator device of the present invention has a structure in which the propulsive force of a plurality of moving coil type actuators is applied to a moving body and a moving member. It is designed to act on the approximate center of gravity.

[0019]

Therefore, according to the moving coil type actuator device of the present invention, when the driving current is supplied to the plurality of moving coils, each moving coil is in the direction along the axial direction thereof and in accordance with the direction of the driving current. The propulsive force in the direction is applied, and the propulsive force generated in the plurality of movable coils acts on the approximate center of gravity of the movable body including the movable body and the movable member. However, the moving body can be moved smoothly, and thus, the electric power required to move the moving body can be reduced.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the moving coil type actuator device of the present invention will be described below with reference to the embodiments shown in the accompanying drawings.

The embodiment shown in the drawings applies the present invention to an actuator device for moving a movable lens in a lens barrel for a camera.

Reference numeral 1 denotes a lens barrel, 2 denotes an outer shell thereof, and the outer shell 2 has an outer shell front half portion 3 and an outer shell rear half portion 4 (only the front end portion thereof is shown in the drawing) connected to each other. By doing so, it is formed to have a substantially prismatic outer shape,
The outer shell front half 3 is formed with an internal space 5 having a substantially circular cross section open at both front and rear ends thereof, and the outer shell rear half 4 is also formed with an internal space substantially similar to the internal space 5. There is.

In the inner space 5, lenses 6 and 7 each having a predetermined light control action are formed, and a light passage hole 8a formed in an intermediate wall 8 forming the front end of the outer shell rear half 4 is formed. The lens 9 and the lens 10 are arranged in an internal space (not shown) of the latter half 4 of the outer shell so that their optical axes coincide with each other. The lens 7 serves as a movable lens for zooming. Is becoming

Reference numerals 5a and 5a are actuator arranging spaces formed on the inner peripheral surface of the inner space 5 so as to extend in the front-rear direction, and the cross-sectional shape thereof is a substantially C-shape opening toward the center of the inner space 5. The two actuator arranging spaces 5a and 5a are located substantially opposite to each other with the center of the internal space 5 in between.

Most of the two actuators of the actuator device described later are separately arranged in these two actuator arrangement spaces 5a, 5a.

Reference numeral 11 denotes an actuator device for moving the movable lens 7, which comprises one moving body 12 and two actuators 13 and 13 '.

The movable body 12 includes a lens holding portion 14, first coil holding portions 15 and 15, and a second coil holding portion 15 '.
15 'and the like are integrally formed of synthetic resin.

The lens holding portion 14 has a flat cylindrical shape having a short axial length for its diameter, and the movable lens 7 is held by the lens holding portion 14.

Reference numerals 16 and 16 'denote connecting portions which are respectively provided rearward from two positions on the outer peripheral portion of the lens holding portion 14 which are substantially opposite to each other with the center of the lens holding portion 14 interposed therebetween. ..

Since the two actuators 13 and 13 'are substantially symmetrical to each other with the moving body 12 interposed therebetween, the structure will be described with reference to one actuator 13 (hereinafter referred to as "first actuator"). .) And the other actuator 13 ′ (hereinafter referred to as “second actuator”) is denoted by the same reference numeral as the reference numeral given to the same portion in the first actuator 13. The description will be omitted by adding the reference numeral with the symbol.

Each of the first coil holding portions 15 and 15 has a substantially ring shape having the same diameter, and a part of the first coil holding portions 15 in the circumferential direction is in front of and behind the surface of the connecting portion 16 facing the side opposite to the lens holding portion 14. The two coil holders 15 and 15 are separately connected to both ends, and the two coil holders 15 and 15 are arranged such that their axes coincide with each other and the axes are parallel to the axis of the lens holder 14.

The moving body 12 is supported by a guide shaft, which will be described later, and is moved along the optical axes of the lenses 6, 7, 9 and 10, and the movement is indicated by a two-dot chain line in FIG. And the position indicated by the alternate long and short dash line.

The actuator 13 comprises a guide shaft also serving as an inner yoke, an outer yoke, two magnets, a movable coil held by the moving body 12, and the like.

Reference numeral 17 denotes a guide shaft composed of a yoke portion 18 having a substantially cylindrical shape and a guide portion 19 having a substantially cylindrical shape. The yoke portion 18 of the guide shaft 17 is formed of a material having a good magnetic permeability. The guide portion 19 is made of a metal having magnetic permeability such as oil-impregnated metal and having a good slidability, and the guide portion 19 is externally fitted to the yoke 18.

The guide shaft 17 is arranged in the front-back direction, that is,
One actuator placement space 5 is oriented in a direction parallel to the optical axis common to the lenses 6, 7, 9 and 10.
It is arranged at the center of a and its both ends are the outer shell front part 3
Are separately supported by the front wall and the intermediate wall 8.

Reference numeral 20 denotes an outer yoke, which has a substantially cylindrical shape having a notch 21 in a part in the circumferential direction. The notch 21 has a central angle about the axis of the outer yoke 20 in a range of about 90 °. The outer yoke 20 is formed over the entire length of the outer yoke 20. Therefore, the outer yoke 20 is substantially C-shaped when viewed in the axial direction.

The outer yoke 20 is arranged in the actuator arranging space 5a so that the notch 21 faces the center of the inner space 5 and the guide shaft 17 is located at the center of the outer yoke 20. It is fixed to the shell first half 3.

Reference numerals 22 and 23 denote magnets, which are formed to have a relatively thick disc shape with notches 24, 24 formed in a part in the circumferential direction, and whose outer diameter is the inner diameter of the outer yoke 20. And a hole 2 having an inner diameter equal to the outer diameter of the guide shaft 17 at its center.
5 and 25 are formed, and the notches 24 and 24 are formed over a range of a central angle of about 90 ° and from the center to the outer peripheral surface. Therefore, the magnets 22 and 23 are also viewed from the axial direction. It is almost C-shaped.

The magnets 22 and 23 are magnetized in the same pattern so as to have different polarities in the direction orthogonal to the axial direction. In the drawing, it is shown in a magnetized state such that the N pole is on the outer surface side and the S pole is on the inner peripheral surface side.

And, such magnets 22 and 2
3 has a direction in which the cutouts 24, 24 coincide with the cutout 21 of the outer yoke 20, the outer peripheral surfaces of which are fixed to the front and rear ends of the inner peripheral surface of the outer yoke 20, and the holes 25, 2 thereof.
The inner peripheral surface of 5 contacts the outer peripheral surface of the guide shaft 17.

The guide shaft 17, the outer yoke 20 arranged so as to surround the guide shaft 17, and the front and rear two magnets 22 and 23 form a space 26 having a substantially circular cross section.
Is defined.

The magnetic flux (indicated by the broken line arrow in FIG. 1) emitted from the two magnets 22 and 23 passes through the two magnetic paths separately.

That is, the magnetic flux emitted from the front magnet 22 passes through the magnetic path of the front half of the outer yoke 20, the front half of the space 26, the front half of the guide shaft 17, and the magnet 22, and then exits from the rear magnet 23. The magnetic flux passes through the magnetic path of the latter half of the outer yoke 20, the latter half of the space 26, the latter half of the guide shaft 17, and the magnet 23.

Reference numeral 27 denotes a coil bobbin, which is a coil winding portion 28 having a substantially cylindrical shape, flanges 29 and 29 projecting outward from both end portions thereof, and an anti-coil winding portion from outer peripheral edges of the flanges 29 and 29. The bearing holding portions 30, 30 projecting toward the 28 side and having an annular shape are integrally formed of an insulating material, and the coil winding portion 28 has an inner diameter slightly larger than the outer diameter of the guide shaft 17. There is.

A movable coil 31 is attached to the coil winding portion 28.
And the ring-shaped bearing metal 32, 32 is press-fitted into the bearing holder 30, 30. Further, the bearing holder 30, 30 is the first coil holder of the moving body 12. It is press-fitted and fixed in the inside of 15, 15 by this,
The movable coil 31 is held by the moving body 12.

Further, the bearing metals 32, 32 have holes 33, 3
The guide shaft 17 is slidably inserted into the shaft 3.

The holes 33 ', 33' of the bearing metal 32 ', 32' of the second actuator 13 'are formed on one side in the shape of a slightly long slot. These bearing metal 32',
32 'is attached to the coil bobbin 27' so that its holes 33 ', 33' are long along the direction toward the guide shaft 17 of the first actuator 13.

Thus, the movable body 12 has the two lenses 6 and 7 on the opposite sides of the center portion thereof supported by the two guide shafts 17 and 17 ', respectively.
The coil holders 15, 15 and 15 ', 15' are supported so as to be movable in a direction parallel to the optical axes 9 and 10.
Only the outer yokes 20, 20 'and the magnets 22, 22', 2 are located in the spaces 26, 26 '.
Notches 21, 21 ', 24, 2 formed in 3, 23'
It is projected to the outside of the spaces 26, 26 'through 4, 24', 24 '.

The movable coils 31, 31 'are positioned in the spaces 26, 26' so that their axial directions extend in a direction orthogonal to the direction of the magnetic flux passing through the spaces 26, 26 '.

Therefore, when the drive current is supplied to the movable coils 31 and 31 '(this supply is performed to the movable coils 31 and 31' at the same timing), the movable coils 31 and 31 'are supplied.
31 'is given a propulsive force in a direction along the axial direction thereof corresponding to the direction of the drive current, so that the movable body 12 is moved forward or backward together with the movable lens 7 by the propulsive force. ..

Since the above-mentioned propulsive force acts on two positions which are equidistantly spaced from each other in the opposite directions from the center of gravity of the movable body composed of the movable body 12 and the movable lens 7,
The resultant force of these two propulsive forces is applied to the position of the center of gravity.

Further, as described above, the bearing metals 32 ', 32' of the second actuator 13 ', the holes 33', 3 '
Since 3'is a long hole which is long in the radial direction of the lens holding portion 14, the distance between the guide shafts 17 and 17 'and the distance between the bearing metals 32, 32 and 32', 32 'are slightly different. Even if there is a dimensional error, the error is absorbed by the holes 33 ', 33', so that the two actuators 13, 13 'can be easily assembled.

Reference numeral 34 denotes a Hall element attached to the inner peripheral surface of the internal space 5 (see FIG. 2), and reference numeral 35 denotes an inclination attached to a part of the outer peripheral surface of the lens holding portion 14 of the movable body 12 protruding. The Hall element 34 and the inclined magnet 35 are magnets, and a detection unit for detecting the position of the moving body 12 is configured.

[0054]

As is apparent from the above description, the movable coil type actuator device of the present invention is one moving body having a plurality of guided holes which are moved in a linear direction and are arranged at appropriate places in the circumferential direction. And a plurality of movable coil type actuators respectively corresponding to the plurality of guided holes, the movable coil type actuator being fitted in the guided holes of the moving body along the moving direction of the moving body. A guide shaft formed of a magnetically permeable material that extends all over or partially in the radial direction of the cross section, a movable coil supported by the moving body so as to be coaxial with the guide shaft, and a substantially cylindrical shape. Therefore, the yoke is arranged so as to surround the moving range of the moving coil and is formed with a notch extending in the axial direction thereof, and is magnetized so that the polarities are different in the direction orthogonal to the axis of the moving coil. And a magnet disposed so as to come into contact with or close to the guide shaft and the yoke at least at one end of the moving range of the movable coil, and the moving member is supported by a portion of the moving body that protrudes to the outside of the yoke through the notch. The propulsive force generated by the plurality of movable coil actuators acts on the approximate center of gravity of the movable body composed of the movable body and the movable member.

Therefore, according to the moving coil type actuator device of the present invention, when the driving current is supplied to the plurality of moving coils, each moving coil is in the direction along the axial direction thereof and in accordance with the direction of the driving current. The propulsive force in the direction is applied, and the propulsive force generated in the plurality of movable coils acts on the approximate center of gravity of the movable body including the movable body and the movable member. However, the moving body can be moved smoothly, and thus, the electric power required to move the moving body can be reduced.

In the above embodiment, the bearing metal is attached to the moving body through the coil bobbin, and the hole of the bearing metal is used as the guided hole. However, the guided hole should be formed directly on the moving body. May be.

Further, in the above embodiment, one magnet is provided before and after the actuator, but one magnet may be provided only on one side, and the magnet is not always required for the guide shaft and the yoke. It is not necessary to bring them into contact with each other, and they may be arranged in a state of being close to the guide shaft and the yoke.

Further, in the above embodiment, the hole of the bearing metal of one of the actuators has a long hole shape, but this hole may be a rectangle having the same width as the diameter of the guide shaft.

In addition, the structures, shapes, etc. of the respective parts shown in the above embodiments are merely examples of the embodiment for carrying out the present invention, and the technical scope of the present invention is limited by these. Should not be construed as.

In particular, although two movable coil type actuators are provided in the above embodiment, the number of the actuators may be three or more.

Further, in the above embodiment, the present invention is applied to the actuator device for moving the movable lens in the lens barrel for the camera, but the present invention is not limited to this kind, and various types. It can be applied to an actuator device for moving the moving member.

[Brief description of drawings]

FIG. 1 shows an example in which the movable coil type actuator device of the present invention is applied to a movable coil type actuator device for moving a movable lens in a camera lens barrel, and the center of the main part of the lens barrel is shown. FIG.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is an enlarged perspective view of a main part showing a part of an outer yoke by cutting away.

FIG. 4 is an exploded perspective view of a main part showing a movable coil by cutting out a part thereof.

FIG. 5 is a perspective view showing an example of a conventional moving coil type actuator device with a part cut away.

[Explanation of symbols]

7 Moving Member 11 Moving Coil Actuator Device 12 Moving Body 13 Moving Coil Type Actuator 13 'Moving Coil Type Actuator 14 Portion of the Moving Body Projected Outside the Yoke 17 Guide Shaft 17' Guide Shaft 20 Yoke 20 'Yoke 21 Notch 21 'Notch 22 Magnet 22' Magnet 23 Magnet 23 'Magnet 31 Moving coil 31' Moving coil 33 Guided hole 33 'Guided hole (long hole)

Claims (2)

[Claims] 1. A moving body having a plurality of guided holes which are moved in a linear direction and arranged at appropriate positions in the circumferential direction, and a plurality of movable coil type actuators respectively corresponding to the plurality of guided holes. The movable coil actuator comprises a material that extends along the moving direction of the moving body while being inserted into the guided hole of the moving body, and is wholly or partially magnetically permeable in the radial direction of the cross section. The formed guide shaft, the movable coil supported by the moving body so as to be coaxial with the guide shaft, and the substantially cylindrical shape are arranged so as to surround the moving range of the movable coil, and in the axial direction thereof. The yoke having the extending notch is magnetized so as to have different polarities in the direction orthogonal to the axis of the movable coil, and the magnet is contacted with or close to the guide shaft and the yoke at least at one end of the movable range of the movable coil. And a magnet disposed in the movable body, the moving body supports the moving member at a portion of the moving body that protrudes to the outside of the yoke through the notch, and the propulsive force by the plurality of moving coil actuators is formed by the moving body and the moving member. A movable coil type actuator device characterized in that it is adapted to act on the approximate center of gravity of a movable body. 2. One of the plurality of guided holes has a circular cross-sectional shape, and the other guided holes have a long cross-sectional shape that is long in the direction toward the center of the one guided hole. The moving coil actuator device according to claim 1, wherein the moving coil actuator device is provided.