JP2014117024A - Linear motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear motor capable of carrying out positioning action with high response and high precision, by improving the stiffness of a motor moving member.SOLUTION: In a linear motor 1, a cylindrical coil frame 21 of a motor moving member 20 is installed between end plate parts 12 and 13 before and behind a moving side frame 10. Opening ends 23 and 24 at both ends of the installed cylindrical coil frame 21 are fixed by an adhesive, while the end plate parts 12 and 13 before and behind the moving side frame 10 are respectively bridged over. By the front and rear end plate part 12 and 13, the cylindrical col frame 21 having low stiffness is held at both ends, and the stiffness of the motor moving member 20 including the cylindrical coil frame 21 can be improved. A resonant frequency of the linear motor 1 can be improved, so that a lens mounted on the moving side frame 10 can be positioned at high-speed with high precision.

Description

  The present invention relates to a linear motor suitable for use in positioning a lens or the like, and more particularly to a linear motor capable of positioning with high response and high accuracy.

  Linear actuators that perform operations such as focusing by moving a lens with good responsiveness using a voice coil motor are widely used. The linear actuator disclosed in Patent Document 1 improves positioning accuracy and durability by matching the center of gravity of a mover that linearly reciprocates with the center of a linear guide that guides the mover.

  The linear actuator disclosed in Patent Document 1 includes a coil and a coil assembly including a rectangular frame-shaped coil frame that supports the coil. Inside the coil assembly, members such as a linear guide, a lens mounting frame, and a mover position detection sensor are arranged.

JP 2008-35645 A

  In the linear actuator of Patent Document 1, each component is incorporated inside a rectangular frame-shaped coil assembly. For this reason, the dimension of a coil assembly becomes comparatively large and sufficient rigidity may not be obtained. When moving a moving part such as a lens frame or a sensor due to a thrust generated between the coil assembly and the permanent magnet on the stator side, the rectangular frame-shaped coil assembly may be deformed without being able to withstand the thrust. . If the rectangular frame-shaped coil assembly is deformed during the movement of the movable part, a slight delay occurs in the movement of the movable element, which may reduce the responsiveness. Further, if the coil assembly is not sufficiently rigid, resonance is likely to occur in the coil assembly during driving. If resonance occurs in the coil assembly, the positioning response and positioning accuracy of the mover may be reduced.

  In view of the above, an object of the present invention is to propose a linear motor capable of performing positioning operation with high response and high accuracy by increasing the rigidity of a motor movable element.

In order to solve the above problems, the linear motor of the present invention is
Fixed side frame,
A movable frame on which the parts to be moved are mounted,
A motor stator fixed to the fixed side frame;
A motor movable element fixed to the movable side frame; and
A linear guide that supports the movable side frame in a slidable state along a predetermined linear movement path with respect to the fixed side frame;
The motor mover includes a cylindrical coil frame, and a drive coil wound around the cylindrical coil frame,
The motor stator includes a drive magnet that generates a magnetic drive force in a direction along the linear movement path between the motor coil and the drive coil.
The movable side frame includes a bottom plate portion fixed to the linear guide, and first and second end plate portions extending vertically from a portion of the bottom plate portion that is separated in the direction of the linear path,
The cylindrical coil frame is mounted between the first and second end plate portions in a state where a central axis thereof is parallel to the linear movement path,
The first end plate portion spans between the opening edge end portions located on both sides across the central axis at the first opening end of one of the cylindrical coil frames. Fixed,
The second end plate portion is bridged between the opening edge end portions located on both sides across the central axis at the other second opening end of the cylindrical coil frame, and It is characterized by being fixed.

  In the linear motor of the present invention, the cylindrical coil frame of the motor movable element is mounted between the first and second end plate portions on both sides of the movable side frame. The first and second end plate portions of the movable frame are bridged over the open ends at both ends of the attached cylindrical coil frame, and are fixed by an adhesive or a metal fitting. The first and second end plate portions support the cylindrical coil frame having low rigidity from both sides, and the rigidity of the motor movable element including the cylindrical coil frame can be increased. Thereby, since the resonant frequency of a linear motor can be raised, the moving object goods mounted in a movable side frame can be positioned with high speed and high precision.

  In the linear motor of the present invention, a mounting portion on which the moving target component is mounted can be disposed on the first end plate portion. In this case, the center of the mounting portion is positioned on a plane including the central axis of the cylindrical coil frame and the linear movement path, and the cylindrical coil frame is symmetrical to the plane. To. In this way, since the thrust is applied to the movable side frame in a bilaterally symmetric state, the movable side frame can be smoothly slid, and the article to be moved can be positioned at high speed and with high accuracy.

  The linear motor of the present invention may have a position detector that detects the position of the motor movable element. In this case, a detector mounting portion is disposed at the first and second opening ends where the tip portions of the first and second end plate portions of the cylindrical coil frame are fixed, A movable detector part of the position detector is disposed.

  If the rigidity of the detector mounting part is not sufficient, the cylindrical coil frame will be deformed or bent during high-speed response or micro-positioning, and the movement of the detector mounting part will be subject to movement of the movable frame. There may be a delay with respect to the movement of the mounting portion. As a result, a difference may occur between the actual movement position of the moving target part and the movement position detected by the position detector (the movement position represented by the detection signal of the detector).

  In the present invention, as described above, the detector mounting portion in the cylindrical coil frame is supported by the first and second end plate portions of the movable side frame from both sides and has sufficiently high rigidity. Therefore, it is prevented or suppressed that the movement of the detector mounting portion is delayed from the actual movement of the movable frame. Thereby, the high-speed response performance and micro positioning performance of a linear motor can be improved.

  In the present invention, the cylindrical coil frame having a cross-sectional shape of a circle, a regular polygon, an ellipse, or an oval can be used.

  In the present invention, when the fixed side frame includes a frame bottom plate portion extending in the direction along the linear movement path, a straight line extending in the direction along the linear movement path is formed on the upper surface of the frame bottom plate portion. A concave portion is formed, and the linear guide is disposed in the concave portion so that the bottom surface of the bottom plate portion of the movable side frame is positioned at substantially the same height as the top surface of the frame bottom plate portion.

  By doing so, it is possible to suppress the occurrence of dead space due to the installation of the linear guide, which is advantageous for reducing the size and size of the linear motor, and also for increasing the rigidity of the fixed side frame.

  Next, when the component to be moved is an optical lens, the mounting portion of the movable side frame is an optical lens mounting through hole penetrating the first end plate portion in the direction of the linear movement path. . In addition, in order to form an optical path passing through the optical lens, a light passing through hole is also formed in the second end plate portion at a position coaxial with the optical lens mounting through hole.

It is a perspective view which shows the principal part of the linear motor to which this invention is applied. It is a front view of the linear motor of FIG. It is a perspective view which takes out and shows the principal part of the movable side assembly of the linear motor of FIG.

  Embodiments of a linear motor to which the present invention is applied will be described below with reference to the drawings. The linear motor according to the present embodiment is used as, for example, a linear actuator for driving a lens for performing lens focusing. It goes without saying that the linear motor of the present invention can be used to linearly reciprocate a moving target component other than the lens.

  FIG. 1 is a perspective view showing a main part of the linear motor according to the present embodiment, FIG. 2 is a front view thereof, and FIG. 3 is a perspective view showing a main part of the movable side assembly. Referring to these drawings, the linear motor 1 includes a fixed side assembly 2 and a movable side assembly 3 on which an optical lens (not shown) as a moving target component is mounted.

  In the fixed side assembly 2, a moving space of the movable side assembly 3 extending in the motor front-rear direction Y is formed at the center portion in the motor width direction X. The movable side assembly 3 is attached to the fixed side assembly 2 via the linear guide 4 and can slide along the linear movement path extending in the motor longitudinal direction Y within the movement space.

  Between the fixed side assembly 2 and the movable side assembly 3, a position detector 5 that detects the moving position of the movable side assembly 3 is arranged as indicated by an imaginary line in FIG. 2. For example, an optical position detector 5 including a light emitting unit 5 a mounted on the movable side assembly 3 and a light receiving unit 5 b mounted on the fixed side assembly 2 is mounted.

  A motor cover 6 is attached to the stationary assembly 2 as shown by phantom lines in FIGS. The motor cover 6 includes a front plate portion 6a that covers the front surface of the motor, left and right side plate portions 6b and 6c that cover the left and right motor side surfaces, and a top plate portion 6d that covers the motor top surface. The motor cover 6 obscures the components of the fixed side assembly 2 and the movable side assembly 3.

  As shown in FIG. 3, the movable side assembly 3 includes a movable side frame 10, a motor movable element 20, a slider 4 a that is a movable side guide component of the linear guide 4, and a light emitting unit 5 a of the position detector 5. .

  The movable side frame 10 includes a bottom plate portion 11 having a rectangular outline extending in the motor front-rear direction, and a front end plate portion 12 and a rear end plate portion 13 standing upright from both ends of the bottom plate portion 11 in the motor front-rear direction. I have. The bottom plate portion 11 is fixed to the upper surface of a slider 4 a that is a movable side guide member of the linear guide 4. The front end plate portion 12 and the rear end plate portion 13 have the same shape, have a substantially rectangular outline that is long in the vertical direction, and are slightly wider at the lower end portion.

  A circular through hole penetrating in the motor front-rear direction Y is formed in the lower end portion of the front end plate portion 12, and this is a lens mounting portion 14 on which a lens that is a moving target component is mounted. A circular through hole 15 for passing light is also formed at the same position in the rear end plate portion 13 so as to penetrate in the front-rear direction of the motor.

  Between the front end plate portion 12 and the rear end plate portion 13 of the movable side frame 10, a motor movable element 20 is mounted from above. The motor mover 20 includes a cylindrical coil frame 21 made of a nonmagnetic material and a drive coil 22 wound around the outer peripheral surface. The cylindrical coil frame 21 is a cylinder having a horizontally long elliptical cross section. The cylindrical coil frame 21 is mounted between the front end plate portion 12 and the rear end plate portion 13 with its center axis L (motor center axis) extending in the motor front-rear direction Y. Note that the cross-sectional shape of the cylindrical coil frame 21 may be a circle, a regular polygon, or an oval.

  In the state where the cylindrical coil frame 21 is mounted, the front end plate portion 12 is bridged between the opening edge end portions 23 a and 23 b positioned above and below the central axis L at the front opening end 23 of the cylindrical coil frame 21. In this state, it is fixed to each of the opening edge portions 23a and 23b. For example, it is fixed by an adhesive. Similarly, the rear end plate portion 13 is bridged between the opening edge end portions 24a and 24b positioned above and below the central axis L at the rear opening end 24 of the cylindrical coil frame 21, and It is fixed to the opening edge portions 24a and 24b.

  Further, in the cylindrical coil frame 21, detector mounting frames 25 and 26 are respectively integrated with the opening edge end portions 23 a and 24 a fixed to the front end portions of the front end plate portion 12 and the rear end plate portion 13. Is formed. The light emitting section 5a of the position detector 5 is mounted in a state of being bridged over the flat upper end surfaces of the front and rear detector mounting frames 25 and 26.

  The movable side assembly 3 having this configuration has a symmetrical structure with respect to a vertical plane P (see FIG. 2) including the central axis L of the cylindrical coil frame 21. On the vertical plane P, the center of the lens mounting portion 14 and the linear movement path of the movable side assembly 3 defined by the linear guide 4 are located.

  Next, as shown in FIGS. 1 and 2, the fixed-side assembly 2 includes a motor cover 6, a fixed-side frame 30, a motor stator 40, a guide rail 4 b that is a fixed-side guide component of the linear guide 4, and position detection. The light receiving part 5b of the device 5 is provided.

  The fixed side frame 30 includes a frame bottom plate portion 31 extending in the front-rear direction of the motor and a frame back plate portion 32 standing upright from the rear end of the frame bottom plate portion 31. The frame bottom plate portion 31 has a concave central portion in the motor width direction. As a result, a concave portion 33 having a rectangular cross section opened upward is formed, and the concave portion 33 extends in the front-rear direction of the motor. A guide rail 4b of the linear guide 4 is fixed to the bottom surface of the recess 33 at the center in the width direction so as to extend in the front-rear direction of the motor. As can be seen from FIG. 2, the depth of the concave portion 33 is substantially the same as the height dimension of the linear guide 4, and the bottom surface 10 a of the movable frame 10 is substantially at the same height as the top surface 31 a of the frame bottom plate portion 31. Yes.

  The motor stator 40 includes left and right drive magnets 41L and 41R that generate magnetic drive force in a direction along the linear movement path, and left and right outer yokes 42L and 42R. The left and right inner yokes 43L and 43R are provided. Each of the outer yokes 42L and 42R made of a ferromagnetic material is fixed to the frame bottom plate portion 31 and the frame back plate portion 32. These are provided on the outer left and right sides of the cylindrical coil frame 21 and have an inner peripheral surface 42a facing the drive coil 22 wound around them with a certain gap. A plurality of drive magnets 41L and 41R are embedded along the inner peripheral surface 42a.

  Inner yokes 43 </ b> L and 43 </ b> R made of a ferromagnetic material are disposed on both sides of the movable frame 10 inside the cylindrical coil frame 21. The inner yokes 43L and 43R have an outer peripheral surface that is opposed to the inner peripheral surface of the cylindrical coil frame 21 by a fixed cap, and extend in the front-rear direction of the motor. 32 is fixed.

  Also in the fixed side assembly 2, the respective components are arranged in a symmetric state with respect to the vertical plane P including the central axis of the cylindrical coil frame 21.

  In addition, a circular through hole (not shown) for passing light is formed in a position corresponding to the lens mounting portion 14 in the frame back plate portion 32 and the cover front plate portion 6a indicated by an imaginary line. As a result, an optical path is formed that extends through the lens mounted on the lens mounting portion 14 and extends in the longitudinal direction of the motor.

  In the linear motor 1 configured as described above, both ends of the cylindrical coil frame 21 are fixed to the front and rear end plate portions 12 and 13 of the movable frame 10, and the cylindrical coil frame 21 has high rigidity. Therefore, the resonance frequency of the linear motor 1 can be increased, and the lens can be positioned with high speed and high accuracy. Further, the light emitting portion 5 a of the position detector 5 is mounted on a portion of the cylindrical coil frame 21 that is fixed to the front end portions of the front and rear end plate portions 12 and 13. Therefore, it is possible to prevent or suppress the adverse effect that the cylindrical coil frame 21 is deformed during high-speed driving or the like, causing a displacement between the position of the mounted component and the detection position by the position detector 5 to generate a positioning error. Positioning control can be performed.

DESCRIPTION OF SYMBOLS 1 Linear motor 2 Fixed side assembly 3 Movable side assembly 4 Linear guide 4a Slider 4b Guide rail 5 Position detector 5a Light emission part 5b Light reception part 6 Motor cover 6a Front plate part 6b, 6c Side plate part 6d Top plate part 10 Movable side frame 11 Bottom plate portion 12 Front end plate portion 13 Rear end plate portion 14 Lens mounting portion 15 Through hole 20 Motor movable element 21 Cylindrical coil frame 22 Drive coil 23 Front opening ends 23a, 23b Opening edge end portion 24 Rear opening end 24a, 24b Opening edge end portions 25, 26 Detector mounting frame 30 Fixed side frame 31 Frame bottom plate portion 32 Frame back plate portion 33 Recess 40 Motor stator 41L, 41R Drive magnet 42L, 42R Outer yoke 43L, 43R Inner yoke X Motor width direction Y Motor longitudinal direction

Claims (6)

Fixed side frame (30),
A movable side frame (10) on which the component to be moved is mounted;
A motor stator (40) fixed to the fixed side frame (30);
A motor movable element (20) fixed to the movable side frame (10), and
A linear guide (4) for supporting the movable frame (10) with respect to the fixed frame (30) in a slidable manner along a predetermined linear movement path;
The motor movable element (20) includes a cylindrical coil frame (21) and a drive coil (22) wound around the cylindrical coil frame (21).
The motor stator (40) includes a drive magnet (41L, 41R) that generates a magnetic drive force in a direction along the linear movement path, between the motor stator (40) and the drive coil (22).
The movable frame (10) extends vertically from a bottom plate portion (11) fixed to the linear guide (4) and a portion of the bottom plate portion (11) that is separated in the direction of the linear path. The second end plate portion (12, 13),
The cylindrical coil frame (21) is mounted between the first and second end plate portions (12, 13) in a state where a central axis thereof is parallel to the linear movement path,
The first end plate portion (12) is between the opening edge end portions (23a, 23b) located on both sides of the central axis at one first opening end (23) of the cylindrical coil frame (21). Is fixed to the opening edge portion (23a, 23b),
The second end plate portion (13) is between the opening edge end portions (24a, 24b) located on both sides of the central axis of the other second opening end (24) of the cylindrical coil frame (21). A linear motor (1) characterized in that the linear motor (1) is fixed to the opening edge portions (24a, 24b) in a state of being stretched over. The first end plate portion (12) includes a mounting portion (14) on which the component to be moved is mounted,
The center of the mounting portion (14) is located on a plane (P) including the central axis of the cylindrical coil frame (21) and the linear movement path,
The linear motor (1) according to claim 1, wherein the cylindrical coil frame (21) has a symmetrical shape with respect to the plane (P). A position detector (5) for detecting the position of the motor movable element (20);
The cylindrical coil frame (21) has a detector mounting portion (25) on the opening edge end portions (23a, 24a) to which the tip ends of the first and second end plate portions (12, 13) are fixed. 26)
The linear motor (1) according to claim 1 or 2, wherein the movable side detector component (5a) of the position detector (5) is fixed to the detector mounting portion (25, 26).   The linear motor (1) according to any one of claims 1 to 3, wherein a cross-sectional shape of the cylindrical coil frame (21) is a circle, a regular polygon, an ellipse, or an oval. The fixed frame (30) includes a frame bottom plate portion (31) extending in a direction along the linear movement path,
On the upper surface (31a) of the frame bottom plate portion (31), a linear recess (33) extending in a direction along the linear movement path is formed,
The linear guide (4) is disposed in the recess (33),
The bottom surface (10a) of the bottom plate portion (11) of the movable side frame (10) is at substantially the same height as the top surface (31a) of the frame bottom plate portion (31). The linear motor (1) according to any one of the above items. The mounting portion (14) of the movable frame (10) is a through hole for mounting an optical lens that passes through the first end plate portion (12) in the direction of the linear movement path,
The said 2nd end-plate part (13) is provided with the through-hole for light passage (15) in the position coaxial with the said through-hole for optical lens mounting, The term of any one of Claim 1 thru | or 5 The linear motor (1) described.

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