JP2005250439A - Imaging apparatus and drive motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the number of parts and to reduce the size of an imaging apparatus while maintaining sufficient generation torque of a drive motor. <P>SOLUTION: The drive motor is provided with: a shaft 40 serving as a center of rotation; a magnet 41 which is two-pole magnetized and rotated around the shaft 40; a turning arm 42 engaged with movable members 26, 27 and turned integrally with the magnet 41, for moving the movable members 26, 27; a stator coil 45 wound in a direction perpendicular to a direction of rotation of the magnet 41 and disposed in such a way to enclose the magnet 41 from outside; a stator yoke 44 disposed outside a coil bobbin 35 on which the stator coil 45 is wound and having a cylindrical circumferential surface part 46; and a position detection means 49 for detecting a rotational position of the magnet 41, wherein a closed magnetic path closed in the rotational direction of the magnet 41 is formed by the circumferential surface part 46 and a magnetic equilibrium holding part 47 for holding a magnetic equilibrium condition between the magnet 41 and the stator yoke 44 during non-energization of the stator coil 45 is formed integrally with the stator yoke 44. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to the technical field of an imaging device and a drive motor. More specifically, the present invention relates to a technical field for reducing the number of parts and reducing the size while maintaining a sufficiently generated torque of a drive motor for moving a movable member constituting an iris or a shutter.

  An imaging device such as a video camera or a still camera includes a lens moving mechanism that moves various lenses for focus control and zooming in the optical axis direction, and an iris for adjusting the amount of light, and a movable member that constitutes the iris ( There is one that adjusts the light amount by opening and closing the optical path of the optical system by moving the aperture blade) by a driving force of a driving motor in a plane orthogonal to the optical axis of the imaging optical system (for example, Patent Documents). 1).

  In such an imaging apparatus, for example, a rotating arm that transmits the driving force of the driving motor to the movable member is provided, and a part of the rotating arm is fixed to the shaft (motor shaft) of the driving motor. An engaging portion provided at the distal end of the moving arm is slidably engaged with an engaging long hole formed in the movable member, and the rotational force of the rotating arm that is rotated in accordance with the rotation of the drive motor is movable. The movable member is moved by being converted into a translational movement force.

  The drive motor described in Patent Document 1 has a configuration in which a magnet is disposed inside a stator yoke, and an output pin (on a rotating arm) provided on the magnet from a notch formed in the stator yoke. (Corresponding member) protrudes outward. Two pins formed of a ferromagnetic material are provided inside the stator yoke so as to be separated from each other in the rotation direction of the magnet, and the output pin rotated with the rotation of the magnet is one of the two pins. As a result, the output pin is held at each moving end in the rotation direction.

  The two pins are planted in a base portion (upper ground plate 1 in Patent Document 1) on which a coil bobbin (coil frame 6b in Patent Document 1) is arranged in the direction of the rotation axis of the magnet.

Japanese Patent No. 3295415

  However, the conventional imaging device described in Patent Document 1 uses two pins formed of a ferromagnetic material in order to hold output pins corresponding to a rotating arm at each moving end in the rotating direction. For this reason, there are a large number of parts, and a large space is required for arranging two pins, which hinders downsizing.

  Two pins are arranged between the inner surface of the stator yoke and the outer surface of the magnet, and a certain gap is formed between the two pins and both. Therefore, there is also a problem that the outer shape of the drive motor is increased by the gap.

  On the other hand, in the case of a drive motor, a ripple-like voltage change may occur during the rotation of the magnet. If such a voltage change occurs and the torque of the drive motor is small, the movable member will move smoothly. Movement is hindered, and in the worst case, the movement of the movable member may stop.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to overcome the above-described problems and to reduce the number of parts and reduce the size while maintaining a sufficient generated torque of the drive motor.

  In order to solve the above-described problems, an imaging device and a drive motor of the present invention are engaged with a shaft that is a rotation center, a magnet that is dipole magnetized and rotated around the shaft, and a magnet that is engaged with a movable member. And a rotating arm that rotates together with the movable member in a direction corresponding to the rotating direction, and is wound around the magnet in a direction orthogonal to the rotating direction of the magnet and arranged to surround the magnet from the outside A stator coil, a coil bobbin around which the stator coil is wound, a stator yoke having a cylindrical peripheral surface portion arranged outside the coil bobbin and penetrating in the axial direction of the shaft, and a position for detecting the rotational position of the magnet Detecting means, a closed magnetic path closed in the rotation direction of the magnet is formed by the peripheral surface portion of the stator yoke, The Tayoku is obtained by forming integrally the magnetic balance holding unit for holding a magnetic equilibrium state between the magnet and the stator yoke in the non-energization of the stator coils.

  In order to solve the above-described problems, another imaging device and a drive motor of the present invention are engaged with a shaft serving as a rotation center, a magnet that is dipole magnetized and rotated around the shaft, and the movable member. A rotating arm that rotates together with the magnet and moves the movable member in a direction corresponding to the rotating direction, and is wound in a direction perpendicular to the rotating direction of the magnet and surrounds the magnet from the outside. A stator coil disposed around the coil, a coil bobbin around which the stator coil is wound, a stator yoke having a cylindrical peripheral surface disposed outside the coil bobbin and penetrating in the axial direction of the shaft, and a rotational position of the magnet. And a closed magnetic circuit closed in the direction of rotation of the magnet by the peripheral surface portion of the stator yoke. , The inner surface of the stator yoke is formed by attaching the magnetic balance holding member for holding a magnetic equilibrium state between the magnet and the stator yoke in the non-energization of the stator coils.

  Therefore, in the image pickup apparatus and the drive motor of the present invention, the magnetic balance state between the magnet and the stator yoke when the stator coil is not energized is achieved by the magnetic balance holding portion formed integrally with the stator yoke. Retained.

  An imaging apparatus according to the present invention includes a moving mechanism that includes a lens barrel having an imaging optical system disposed therein, an iris or a shutter, and a movable member that opens and closes an optical path of the imaging optical system, and a driving motor that is a driving source of the moving mechanism. The drive motor includes a shaft that is the center of rotation, a magnet that is dipole magnetized and rotated about the shaft, and is engaged with the movable member and integrated with the magnet. A rotating arm that rotates and moves the movable member in a direction corresponding to the rotating direction, and a stator coil that is wound in a direction orthogonal to the rotating direction of the magnet and that surrounds the magnet from the outside A coil bobbin around which the stator coil is wound, and a cylindrical peripheral surface portion that is disposed outside the coil bobbin and penetrates in the axial direction of the shaft. And a position detecting means for detecting the rotational position of the magnet, and a closed magnetic path closed in the direction of rotation of the magnet is formed by the peripheral surface portion of the stator yoke, and when the stator coil is not energized to the stator coil A magnetic balance holding unit that holds a magnetic balance between the magnet and the stator yoke is integrally formed.

  Therefore, the number of parts can be reduced as compared with the case where a dedicated separate member is provided as the magnetic balance holder, and the size of the magnetic balance holder can be reduced because the arrangement space of the magnetic balance holder is small.

  Further, since the closed magnetic path closed in the rotation direction of the magnet is formed by the peripheral surface portion of the stator yoke, there is little leakage of magnetic flux, and the operation reliability can be improved by improving the torque of the drive motor.

  Furthermore, low power consumption can be achieved by improving the torque of the drive motor.

  In the invention described in claim 2, since the protrusion protruding from the peripheral surface portion is provided as the magnetic balance holding portion of the stator yoke, the configuration is simple, and the configuration of the drive motor is simplified. In addition, the torque of the drive motor can be improved without increasing the cost.

  In the invention described in claim 3, the projecting portion is projected from the inner surface of the peripheral surface portion to the coil bobbin side, so that the drive motor can be miniaturized.

  In the invention described in claim 4, since the protrusion is protruded from the outer surface of the peripheral surface portion to the side opposite to the coil bobbin, the internal space of the peripheral surface portion can be effectively utilized.

  In the invention described in claim 5, since the hole or notch is formed in the peripheral surface portion as the magnetic balance holding portion of the stator yoke, it is not necessary to provide a protrusion as the magnetic balance holding portion, so that the formation is easy. In addition, it is possible to reduce the size of the drive motor and effectively use the internal space of the peripheral surface portion.

  In the invention described in claim 6, the peripheral surface portion of the stator yoke is constituted by an arc surface portion and a plane portion positioned between both ends in the circumferential direction of the arc surface portion, and the plane portion is used as a magnetic equilibrium holding portion. Since the flat portion is formed, the drive motor can be reduced in size as compared with the case where the whole is formed in a cylindrical shape.

  Another imaging device of the present invention is a moving mechanism having a lens barrel having an imaging optical system disposed therein and an iris or shutter, and a movable member that opens and closes the optical path of the imaging optical system, and serves as a drive source for the moving mechanism An image pickup apparatus including a drive motor, wherein the drive motor is engaged with the movable member and a magnet that is dipolarly magnetized and rotated around the shaft. And a rotating arm that rotates together with the movable member in a direction corresponding to the rotating direction, and is wound around the magnet in a direction orthogonal to the rotating direction of the magnet and arranged to surround the magnet from the outside A stator coil, a coil bobbin around which the stator coil is wound, and a cylindrical peripheral surface portion that is disposed outside the coil bobbin and penetrates in the axial direction of the shaft A stator yoke and position detecting means for detecting the rotational position of the magnet, and a closed magnetic path closed in the direction of rotation of the magnet is formed by the peripheral surface portion of the stator yoke, and the stator yoke is connected to the stator coil on the inner surface thereof. A magnetic balance holding member for holding a magnetic balance between the magnet and the stator yoke when energized is attached.

  Therefore, since the arrangement space of the magnetic balance holder is small, the size can be reduced.

  Further, since the closed magnetic path closed in the rotation direction of the magnet is formed by the peripheral surface portion of the stator yoke, there is little leakage of magnetic flux, and the operation reliability can be improved by improving the torque of the drive motor.

  Furthermore, low power consumption can be achieved by improving the torque of the drive motor.

  The drive motor of the present invention is a drive motor that serves as a drive source for a moving mechanism that opens and closes an optical path of an imaging optical system that has a movable member that constitutes an iris or a shutter and that is disposed inside a lens barrel. And a magnet that is dipole magnetized and rotated around the shaft, and is engaged with the movable member and rotated integrally with the magnet to move the movable member in a direction corresponding to the rotational direction. A rotating arm to be wound, a stator coil wound in a direction orthogonal to the magnet rotation direction and arranged to surround the magnet from the outside, a coil bobbin around which the stator coil is wound, and an outer side of the coil bobbin A stator yoke having a cylindrical peripheral surface portion that is disposed and penetrated in the axial direction of the shaft, and a position detection that detects the rotational position of the magnet. A closed magnetic path is formed in the rotation direction of the magnet by the peripheral surface portion of the stator yoke, and the stator yoke has a magnetic equilibrium state between the magnet and the stator yoke when the stator coil is not energized. The magnetic balance holding portion for holding the head is integrally formed.

  Therefore, the number of parts can be reduced as compared with the case where a dedicated separate member is provided as the magnetic balance holder, and the size of the magnetic balance holder can be reduced because the arrangement space of the magnetic balance holder is small.

  Further, since the closed magnetic path closed in the rotation direction of the magnet is formed by the peripheral surface portion of the stator yoke, there is little leakage of magnetic flux, and the operation reliability can be improved by improving the torque.

  Furthermore, low power consumption can be achieved by improving torque.

  In the invention described in claim 9, since the protrusion protruding from the peripheral surface portion is provided as the magnetic balance holding portion of the stator yoke, the configuration is simple and the configuration of the drive motor is simplified. In addition, the torque of the drive motor can be improved without increasing the cost.

  In the invention described in claim 10, since the protruding portion protrudes from the inner surface of the peripheral surface portion toward the coil bobbin side, the drive motor can be reduced in size.

  In the invention described in claim 11, since the protruding portion is protruded from the outer surface of the peripheral surface portion to the side opposite to the coil bobbin, the internal space of the peripheral surface portion can be effectively utilized.

  In the invention described in claim 12, since the hole or notch is formed in the peripheral surface portion as the magnetic balance holding portion of the stator yoke, it is not necessary to provide a protrusion as the magnetic balance holding portion, so that the formation is easy. In addition, it is possible to reduce the size of the drive motor and effectively use the internal space of the peripheral surface portion.

  In the invention described in claim 13, the peripheral surface portion of the stator yoke is constituted by an arc surface portion and a plane portion positioned between both ends in the circumferential direction of the arc surface portion, and the plane portion is used as a magnetic equilibrium holding portion. Since the flat portion is formed, the drive motor can be reduced in size as compared with the case where the whole is formed in a cylindrical shape.

  Another drive motor according to the present invention is a drive motor that serves as a drive source for a moving mechanism that opens and closes an optical path of an imaging optical system that has a movable member constituting an iris or a shutter and is arranged inside a lens barrel. A shaft that is centered, a magnet that is dipole magnetized and rotated about the shaft, and a direction that is engaged with the movable member and that rotates together with the magnet in accordance with the direction of rotation. A rotating arm to be moved, a stator coil wound in a direction orthogonal to the rotation direction of the magnet and arranged to surround the magnet from the outside, a coil bobbin around which the stator coil is wound, and a coil bobbin A stator yoke having a cylindrical peripheral surface portion disposed outside and penetrating in the axial direction of the shaft, and a position for detecting the rotational position of the magnet. And a closed magnetic path that is closed in the rotation direction of the magnet by the peripheral surface portion of the stator yoke, and the magnetic surface between the magnet and the stator yoke when the stator coil is not energized is formed on the inner surface of the stator yoke. A magnetic balance holding member that holds a balanced state is attached.

  Therefore, since the arrangement space of the magnetic balance holder is small, the size can be reduced.

  Further, since the closed magnetic path closed in the rotation direction of the magnet is formed by the peripheral surface portion of the stator yoke, there is little leakage of magnetic flux, and the operation reliability can be improved by improving the torque.

  Furthermore, low power consumption can be achieved by improving torque.

  The best mode for carrying out the imaging apparatus and the drive motor of the present invention will be described below with reference to the accompanying drawings. In the best mode described below, the imaging apparatus of the present invention is applied to a video camera, and the driving motor of the present invention is applied to a driving motor used in the video camera. Note that the scope of application of the present invention is not limited to a video camera or a drive motor used therefor, and the present invention is not limited to a still camera, but to various imaging devices having functions of moving image shooting or still image shooting, or these. It can be applied to the drive motor used.

  First, the basic configuration of the imaging apparatus (video camera) will be described (see FIG. 1).

  The imaging apparatus 1 includes a lens barrel 2 provided as an outer casing, and required parts are arranged. The lens barrel 2 includes a lens or a lens group 3 (shown in the drawing as a single lens for simplification). And an image pickup means 4 such as a solid-state image pickup device, and an iris or shutter, or a moving mechanism 5 having both functions.

  The pair of movable members 6, 6 constituting the moving mechanism 5 are moved by the driving force of the drive motor 7, and moving the movable members 6, 6 opens and closes the optical path of the optical system. As the drive motor 7, a so-called inner rotor type motor in which a rotor is arranged inside the stator is used, and the drive force of the drive motor 7 is transmitted to the movable members 6, 6 to move the movable members 6, 6. .

  The light passing through the lens or the lens group 3 from the subject enters the imaging means 4 through an aperture formed by a diaphragm blade or a shutter member provided as a pair of movable members 6 and 6. When adjusting the amount of light, the movable members 6 and 6 are translated in a plane orthogonal to the optical axis OL. However, in the application of the present invention, one or the number of movable members is not limited. Implementation in various forms using a plurality of movable members is possible.

  As the drive motor 7, it is preferable to use a voice coil type in consideration of ensuring a sufficient generated torque and dealing with an increase in shutter speed, but a linear motor or the like is used if necessary. Is also possible.

  Next, a specific configuration example of the imaging device will be described (see FIGS. 2 to 16).

  As shown in FIG. 2, the lens barrel 9 of the imaging device 8 includes an objective lens 10, a variable magnification lens 11, a lens 12, a moving mechanism 13, a drive motor 14, a focus lens 15, and a solid-state imaging element in order from the subject side. 16 is arranged. Although the moving mechanism 13 has functions of an iris or a shutter or both of them, a case where the moving mechanism 13 has functions of both an iris and a shutter will be described below.

  Inside the lens barrel 9, guide bars 17, 17 and guide bars 18, 18 parallel to the optical axis OL are arranged at positions opposite to each other in the optical axis OL direction across the moving mechanism 13. ing.

  The variable magnification lens 11 is held by a holder 19, and the holder 19 is slidably supported by guide bars 17 and 17. The zoom lens 11 held by the holder 19 is moved in the direction along the optical axis OL when the driving force of the zoom lens driving unit 20 is transmitted to the holder 19.

  The focus lens 15 is held by a holder 21, and the holder 21 is slidably supported by guide bars 18 and 18. The focus lens 15 held by the holder 21 is moved in the direction along the optical axis OL when the driving force of the focus lens drive unit 22 is transmitted to the holder 21.

  The image output obtained by the solid-state imaging device 16 is sent to the image processing unit 23 and subjected to predetermined processing. The image processing unit 23 sends information necessary for control or the like to the arithmetic processing unit 24, sends the photographed image to a viewfinder, a monitor or the like to display it, or records image information or the like on a recording medium in accordance with a user operation instruction. Let The arithmetic processing unit 24 having a microcomputer or the like sends a control command signal to the control unit 25, and control signals are transmitted from the control unit 25 to the drive motor 14, the zoom lens drive unit 20, the focus lens drive unit 22, and the like. Each part is controlled by being supplied.

  As shown in FIG. 3, the moving mechanism 13 has a pair of diaphragm blades that function as movable members 26 and 27, and by moving the movable members 26 and 27, the function of adjusting the amount of incident light and the shutter function are provided. I also use it. Since the moving mechanism 13 is incorporated in the lens barrel 9 without protruding from the outer peripheral surface of the lens barrel 9, there is no problem of interference with other parts, and the size and size of the moving mechanism 13 are reduced. It is suitable for conversion.

  The movable member 26 is formed by integrally forming a main portion 28 and projecting portions 29 and 29 projecting downward from both left and right end portions of the main portion 28. The movable member 26 is formed with an opening notch 26a opened downward.

  The main portion 28 is formed with a long guided hole 28a on one side edge and a long engagement long hole 28b on the upper and lower sides.

  The protrusions 29 and 29 are respectively provided with guided holes 29a and 29a that are long in the vertical direction.

  The movable member 27 is formed by integrally forming a main portion 30 and a protrusion 31 protruding upward from one side edge portion of the main portion 30. The movable member 27 is formed with an opening notch 27a opened upward. The main portion 30 is formed with guided holes 30a and 30a that are long on the left and right side edges.

  The protrusion 31 is formed with a guided hole 31a that is long in the vertical direction. A long engagement slot 31b is formed on the upper end of the protrusion 31 on the left and right.

  The movable members 26 and 27 are respectively supported by the base body 32 so as to be movable in the vertical direction (see FIGS. 4 and 5).

  The base body 32 is formed in a vertically long shape, and has mounting grooves 32a and 32a on the left and right side edges, respectively. The base body 32 is provided with four guide pins 32b, 32b,. A transmission hole 32c is formed in a substantially central portion of the base body 32, and the optical axis OL of the optical system is set at a position passing through the center of the transmission hole 32c.

  The three guide pins 32b, 32b, 32b of the base body 32 are respectively inserted into the guided holes 28a, 29a, 29a of the movable member 26 and are slidably engaged. Further, the three guide pins 32b, 32b, 32b of the base body 32 are inserted into the guided holes 30a, 30a, 31a of the movable member 27 and are slidably engaged. That is, the two guide pins 32 b and 32 b are engaged with the guided holes 29 a and 29 a of the movable member 26 and the guided holes 30 a and 30 a of the movable member 27, and another guide pin 32 b is guided by the guided hole of the movable member 26. The other guide pin 32 b is engaged only with the guided hole 31 a of the movable member 27.

  In a state where the movable members 26 and 27 are supported by the base body 32, the cover body 33 is attached. The cover body 33 is formed in a vertically long shape, and a large opening 33 a is formed at the center of the cover body 33. Mounted protrusions 33b and 33b are provided on the left and right side edges of the cover body 33, respectively. In the cover body 33, four attached holes 33c, 33c,... Are formed.

  In the cover body 33, the attachment protrusions 33b, 33b are attached to the attachment grooves 32a, 32a, respectively, and the guide pins 32b, 32b,... Are inserted into the attachment holes 33c, 33c,. It is attached to the base body 32 so as to cover the movable members 26 and 27 (see FIG. 5). The opening 33 a of the cover body 33 is made larger than the transmission hole 32 c of the base body 32, and the transmission hole 32 c is located in the opening 33 a in a state where the cover body 33 is attached to the base body 32.

  A motor attachment member 34 is attached to the upper end portion of the base body 32 (see FIGS. 4 and 5). Insertion holes 34a and 34a are formed in the motor attachment member 34 so as to be separated from each other in the left-right direction, and the insertion holes 34a and 34a are each formed in an arc shape protruding outward.

  The drive motor 14 is an inner rotor type, and is a movable magnet type in which a magnet is provided in the rotor and a coil is provided in the stator (see FIGS. 6 to 9).

  The drive motor 14 includes a coil bobbin 35, and the coil bobbin 35 is formed by coupling a first member 36 and a second member 37 (see FIG. 7).

  The first member 36 is formed with a bearing hole 36a at the center thereof, and the bearing hole 36a functions as a radial bearing of a shaft described later. Arrangement grooves 36b and 36b extending in the radial direction are formed in the first member 36, and the arrangement grooves 36b and 36b are positioned 180 ° opposite to each other across the central portion of the first member 36. . The first member 36 is provided with winding protrusions 36c and 36c that are positioned in parallel on the surface on which the arrangement grooves 36b and 36b are formed and the surface on the opposite side (FIGS. 7 and 9). reference).

  An arrangement recess 37a is formed at the center of the second member 37 (see FIG. 7). A bearing portion 37b is provided inside the arrangement recess 37a, and the bearing portion 37b functions as a thrust bearing and a radial bearing of a shaft, which will be described later. Arrangement grooves 37c and 37c extending in the radial direction are formed in the second member 37, and the arrangement grooves 37c and 37c are positioned 180 ° opposite to each other across the central portion of the second member 37. . The second member 37 is provided with winding protrusions 37d and 37e on the surface on which the arrangement grooves 37c and 37c are formed and the surface opposite to the body (see FIGS. 7 and 8).

  The winding projection 37d is thicker than the winding projection 37e, and the winding projection 37d is formed with an arrangement notch 37f (see FIG. 6).

  The first member 36 and the second member 37 are coupled with the arrangement grooves 36b and 36b and the arrangement grooves 37c and 37c facing each other to constitute the coil bobbin 35 (see FIG. 7). In the state in which the coil bobbin 35 is configured, two arrangement holes 38 and 38 that communicate between the inside and the outside of the coil bobbin 35 are formed by the arrangement grooves 36b and 36b and the arrangement grooves 37c and 37c that face each other.

  The rotor 39 of the drive motor 14 has a shaft 40 and a magnet 41 (see FIG. 7).

  The shaft 40 is disposed so that the axial direction thereof is along the optical axis OL, and both ends of the shaft 40 are rotatably supported in the bearing hole 36a of the first member 36 and the bearing portion 37b of the second member 37, respectively. Has been.

  The magnet 41 is formed in a cylindrical shape and is two-pole magnetized. The magnet 41 is arranged in the arrangement concave portion 37a of the second member 37, and is fixed to the portion excluding both ends in the axial direction of the shaft 40 in an outer fitting shape.

  The rotating arm 42 is formed integrally with the shaft 40. The rotating arm 42 includes arm portions 42a and 42a and engagement shaft portions 42b and 42b provided at the respective distal ends of the arm portions 42a and 42a. The arm portions 42 a and 42 a are continuous with the shaft 40 and protrude in a direction perpendicular to the axial direction of the shaft 40. The arm portions 42a and 42a protrude from the shaft 40 in directions opposite to each other by 180 °. The engagement shaft portions 42b and 42b protrude in the same direction orthogonal to the arm portions 42a and 42a.

  As for the rotation arm 42, the front-end | tip part of arm part 42a, 42a and the engaging shaft part 42b, 42b protrude outward from the arrangement | positioning holes 38, 38 of the coil bobbin 35 (refer FIG. 7).

  The stator 43 of the drive motor 14 has a stator yoke 44 and a stator coil 45.

  For example, as shown in FIG. 10, the stator yoke 44 is formed by bending a magnetic metal material having a rectangular plate shape into a cylindrical shape and bending one end portion thereof inwardly. A protrusion 47 protruding inward from the peripheral surface portion 46 is formed integrally. The connection of the contact surface 46a of the peripheral surface portion 46 is performed by appropriate means such as adhesion or welding. The protrusion 47 functions as a magnetic equilibrium holding portion that holds a magnetic equilibrium state between the magnet 41 and the stator yoke 44 when the stator coil 45 is not energized.

  The stator yoke 44 is positioned so as to be biased toward one end in the axial direction with respect to the magnet 41, and the magnet 41 is attracted to the biased side. Accordingly, the shaft 40 is urged toward the bearing portion 37b of the second member 37 and is pressed against the bottom surface portion of the bearing portion 37b that functions as a thrust bearing.

  A closed magnetic path closed in the circumferential direction is formed in the drive motor 14 by the peripheral surface portion 46 of the stator yoke 44.

  The stator yoke 44 is attached to the coil bobbin 35 so as to be fitted onto the coil bobbin 35. When the stator yoke 44 is attached to the coil bobbin 35, the protrusion 47 has a winding protrusion 37 e and a peripheral surface portion of the second member 37 of the coil bobbin 35. 46 (see FIG. 6).

  The stator coil 45 is wound on the outer surface side of the coil bobbin 35 between the winding protrusions 36c and 36c and between the winding protrusions 37d and 37e (see FIGS. 6 to 9). The stator coil 45 is wound in a direction orthogonal to the rotation direction of the magnet 41.

  A wiring board 48 is attached to the coil bobbin 35 (see FIG. 6). The wiring board 48 is a flexible printed wiring board, for example, and the front-end | tip part is bent. Both end portions of the stator coil 45 are connected to terminal electrodes (not shown) of the wiring board 48, and the stator coil 45 is energized from a power supply circuit (not shown) via the wiring board 48. A hall element 49 that functions as a position detection unit that detects the rotation direction and rotation position of the magnet 41 is provided at the tip of the wiring board 48. The front end portion of the wiring board 48 provided with the Hall element 49 is inserted into an arrangement notch 37f formed in the winding projection 37d of the coil bobbin 35, and the Hall element 49 is disposed at a position facing the outer peripheral surface of the magnet 41. Is done.

  The drive motor 14 is attached to a motor attachment member 34 (see FIGS. 4 and 5). When the drive motor 14 is attached to the motor attachment member 34, the engagement shaft portions 42b and 42b of the rotating arm 42 are inserted into the insertion holes 34a and 34a, respectively, and the engagement long holes 28b of the movable members 26 and 27 are inserted. , 31b is slidably engaged.

  By engaging the engaging shaft portions 42b and 42b of the rotating arm 42 with the engaging elongated holes 28b and 31b of the movable members 26 and 27, respectively, the rotating arm 42 is rotated as the rotor 39 rotates. Then, the movable members 26 and 27 are translated by the guide pins 32b, 32b,.

  The rotatable angle θ of the rotor 39 is, for example, 60 ° (see FIG. 11), and the opening edges of the arrangement holes 38, 38 of the coil bobbin 35 function as a stopper for restricting the rotation of the rotor 39. Accordingly, the rotation of the rotor 39 is restricted by the arm portions 42a and 42a of the rotating arm 42 being in contact with the opening edges of the arrangement holes 38 and 38 at the rotation angles of 0 ° and 60 °, respectively.

  The hall element 49 is disposed at a position (center position) that is a half of the rotatable angle θ of the rotor 39, for example, at a position of 30 ° (see FIG. 11). The rotatable angle θ is a range through which the neutral line NL that is the position between the magnetic poles passes through the rotation of the magnet 41, and the Hall element 49 outputs a detection signal corresponding to the rotation direction and the rotation position of the magnet 41 with the center position as a reference. To do.

  FIG. 12 schematically shows the detection level of the Hall element 49, and the horizontal line “V0” in the figure indicates the detection level (reference level) at the center position.

  When the rotation direction of the rotor 39 is, for example, the first direction “CW” shown in FIG. 11, the detection level of the Hall element 49 gradually decreases as indicated by “ga”, and further after crossing V0 The detection level is reduced. On the other hand, when the rotation direction of the rotor 39 is the second direction “CCW” shown in FIG. 11, the detection level of the Hall element 49 gradually increases from a state below V0 as shown by “gb”. After crossing, the detection level further increases. As described above, the rotation direction of the magnet 41 of the rotor 39 is detected based on the change in polarity with respect to V0, and the rotation position of the magnet 41 can be detected from the magnitude of the detection level with reference to V0. it can. The detection signal of the Hall element 49 is sent to the control unit 25 and processed, and the rotation of the rotor 39 is controlled by the signal sent to the drive motor 14 based on this detection information.

  In the drive motor 14, since the Hall element 49 is used as a detection means for the rotation direction and rotation position of the rotor 39, the rotation direction and rotation position of the rotor 39 can be easily and accurately performed.

  As described above, the rotor 39 is rotated, for example, at a rotation angle of 60 °, and one end of the rotation angle (rotation angle 0 °) is the first rotation in which the movable members 26 and 27 block the optical path of the imaging optical system. The other end (rotation angle 60 °) of the rotation angle is a second rotation position (see FIG. 14) where the movable members 26 and 27 open the optical path of the imaging optical system.

  In the drive motor 14, as shown in FIG. 13, the protrusion 47 of the stator yoke 44 is set at a position near the line segment H orthogonal to the neutral line NL. That is, in a state where the magnet 41 is in the first rotation position, the magnet 41 protrudes to a position that is counterclockwise (CCW) 90 ° from the first rotation position and is spaced counterclockwise by an angle α. Part 47 is located. As shown in FIG. 14, the position of the protrusion 47 is a position on the clockwise direction (CW) side from the neutral line NL located in the vicinity in a state where the magnet 41 is in the second rotational position.

  By setting the position of the protrusion 47 to the position as described above, the rotor 39 has one magnetic pole of the magnet 41, for example, the central portion A (see FIG. 13) in the circumferential direction of the N pole on the protrusion 47. A biasing force is applied in a direction in which the stator coil 45 is attracted, that is, a direction in which a magnetic equilibrium state between the magnet 41 and the stator yoke 44 is maintained when the stator coil 45 is not energized. When energized, a rotational force in the counterclockwise direction (CCW) is applied to the shaft 40, the magnet 41, and the rotating arm. As described above, the rotor 39 can rotate only to the position where the arm portions 42a, 42a of the rotating arm 42 are in contact with the opening edges of the arrangement holes 38, 38 of the stator yoke 44. The magnet 41 is held at the first rotational position while being attracted to the first position.

  Next, the operation of the movable members 26 and 27 accompanying the rotation of the rotor 39 will be described (see FIGS. 15 and 16).

  When the rotating arm 42 is rotated in the clockwise direction (CW) shown in FIG. 11 along with the rotation of the rotor 39 by energization of the stator coil 45, the movable members 26 and 27 are mutually connected as shown in FIG. The light quantity of the incident light increases as the area of the opening 50 formed by the opening notches 26a and 27a of the movable members 26 and 27 is increased and the transmission hole 32c is opened. Conversely, when the rotating arm 42 is rotated in the counterclockwise direction (CCW) shown in FIG. 11, the movable members 26 and 27 are moved toward each other as shown in FIG. The area of the opening 50 formed by the 27 opening notches 26a and 27a is reduced and the transmission hole 32c is closed, whereby the amount of incident light is reduced.

  Accordingly, the amount of light transmitted through the transmission hole 32 c of the base body 32 is adjusted according to the size of the opening 50 formed by the movable members 26 and 27.

  When the energization to the stator coil 45 is stopped while the rotor 39 is rotated in the CW direction, the rotor 39 is rotated in the CCW direction so that the magnet 41 is magnetically balanced, and the magnet 41 is moved to the first rotational position. The optical path of the optical system is closed. Therefore, for example, even if the supply of power to the drive motor 14 is interrupted, the optical path of the optical system is reliably blocked, and the solid-state imaging device 16 can be protected.

  In order to return the magnet 41 to the first rotation position at a high speed, the stator coil 45 may be energized in a direction in which the rotor 39 is rotated in the CCW direction.

  As described above, in the drive motor 14, the peripheral surface portion 46 of the stator yoke 44 maintains a magnetic equilibrium state between the magnet 41 and the stator yoke 44 when the stator coil 45 is not energized. Since the protrusion 47 that functions as a magnetic balance holder is integrally formed, the number of parts can be reduced as compared with the case where a dedicated separate member is provided as the magnetic balance holder. Since the arrangement space of the part is small, the size can be reduced.

  Further, since the closed magnetic path closed in the rotation direction of the magnet 41 is formed by the peripheral surface portion 46 of the stator yoke 44, there is little leakage of magnetic flux, and the operation reliability is improved by improving the torque of the drive motor 14. Can do.

  Furthermore, the power consumption can be reduced by improving the torque of the drive motor 14.

  Furthermore, since the protrusion 47 protruding from the peripheral surface portion 46 of the stator yoke 44 is used as the magnetic balance holding portion, the configuration is simple, the configuration of the drive motor 14 can be simplified, and the cost can be reduced. The torque of the drive motor 14 can be improved without causing a surge.

  In addition, since the protruding portion 47 protrudes from the inner surface of the peripheral surface portion 46 toward the coil bobbin 35, the drive motor 14 can be reduced in size accordingly.

  Hereinafter, modifications of the stator yoke will be shown (see FIGS. 17 to 29).

  As shown in FIG. 17, the stator yoke 44 </ b> A according to the first modification is formed inwardly with the circumferential surface portion 46 </ b> A by indenting a part of a cylindrically formed portion with a magnetic metal material, for example. The protruding protrusion 47A is integrally formed.

  The protrusion 47A may be formed in a portion excluding both end portions in the axial direction of the circumferential surface portion 46A as shown in FIG. 18, and a portion on one side in the axial direction of the circumferential surface portion 46A as shown in FIG. It may be formed.

  The stator yoke 44A can be formed easily and in a short time because there is no need to form a peripheral surface portion by bending a plate-like material and bonding both ends thereof by adhesion or the like.

  As shown in FIG. 20, the stator yoke 44B according to the second modification is formed by forming a hole 47B functioning as a magnetic balance holding portion in the peripheral surface portion 46B. A plurality of holes 47B may be formed in the axial direction of the peripheral surface portion 46B. Further, instead of the hole 47B, a notch or a slit may be formed.

  In the stator yoke 44B, since the hole 47B is formed as a magnetic equilibrium holding portion, the neutral line NL of the magnet 41 is rotated so as to be attracted to the hole 47B when the stator coil 45 is not energized. Therefore, it is necessary to set the first rotation position and the second rotation position of the magnet 41 at positions that take this into account.

  In the stator yoke 44B, it is not necessary to provide a protrusion as a magnetic balance holding portion, so that the formation is easy, and the drive motor 14 can be downsized and the internal space of the peripheral surface portion 46B can be effectively utilized. it can.

  As shown in FIG. 21, the stator yoke 44C according to the third modification is formed by integrally forming a flat portion 47C functioning as a magnetic balance holding portion and an arcuate surface portion 51 positioned between both ends of the flat portion 47C. Become.

  In the stator yoke 44C, when the stator coil 45 is not energized, the magnet 41 is rotated so that the central portion A (see FIG. 13) of the magnetic pole is attracted to the flat portion 47C functioning as a magnetic balance holding portion. .

  The stator yoke 44C can be formed easily and in a short time because it is not necessary to form the flat portion 47C and the arcuate surface portion 51 by bending a plate-like material and bonding both ends thereof by adhesion or the like.

  Further, since the flat portion 47C is formed, the drive motor 14 can be reduced in size as compared with the case where the whole is formed in a cylindrical shape.

  As shown in FIG. 22, the stator yoke 44D according to the fourth modification includes a peripheral surface portion 46D and a protrusion 47D, and the protrusion 47D is formed in a triangular shape.

  As shown in FIG. 23, the stator yoke 44E according to the fifth modification includes a peripheral surface portion 46E and a protrusion 47E, and the tip of the protrusion 47E is formed in a semicircular shape.

  As shown in FIG. 24, the stator yoke 44 </ b> F according to the sixth modification includes a peripheral surface portion 46 </ b> F and a protrusion 47 </ b> F, and the protrusion 47 </ b> F is inclined with respect to the direction in which the rotation center of the magnet 41 is positioned. It is a protruding one.

  As shown in FIG. 25, the stator yoke 44G according to the seventh modification includes a peripheral surface portion 46G and a protrusion 47G, and the protrusion 47G protrudes inward from one end in the axial direction of the peripheral surface portion 46G. It is a thing.

  As shown in FIG. 26, the stator yoke 44H according to the eighth modified example includes a peripheral surface portion 46H and a protrusion 47H. The protrusion 47H is cut out from a part of the peripheral surface portion 46H, and the notched portion. Is formed by bending inward and projecting inward. The protrusion 47H is bent so that the main surface thereof faces the axial direction of the peripheral surface portion 46H.

  As shown in FIG. 27, the stator yoke 44I according to the ninth modified example includes a peripheral surface portion 46I and a protruding portion 47I. The protruding portion 47I is cut out from a part of the peripheral surface portion 46I, and the cut-out portion. Is formed by bending inward and projecting inward. The protrusion 47I is bent so that the main surface thereof faces in a direction orthogonal to the axial direction of the peripheral surface portion 46I.

  The stator yoke 44G according to the seventh modified example, the stator yoke 44H according to the eighth modified example, and the stator yoke 44I according to the ninth modified example all have peripheral surfaces 46G, 46H, 46I formed in a predetermined shape. Since the protrusions 47G, 47H, and 47I are formed by bending a part thereof inward, the processing is easy.

  As shown in FIG. 28, the stator yoke 44J according to the tenth modification is attached to a circumferential surface portion 46J formed in a cylindrical shape by adhesion or welding to a circumferential surface portion 46J and the inner surface of the circumferential surface portion 46J, for example. And a magnetic pin 52 which is a ferromagnetic material such as iron. The magnetic pin 52 is attached to the peripheral surface portion 46J so as to extend in the axial direction of the peripheral surface portion 46J.

  The cross-sectional shape of the magnetic pin 52 can be selected from an arbitrary shape such as a circle, a rectangle, and a triangle.

  In addition, the attachment of the magnetic pin 52 is not limited to adhesion or welding. As shown in FIG. 29, two slits are formed in the peripheral surface portion 46J, and the portion between the slits protrudes inward to cause the magnetic pin 52 to be attached. It may be performed by inserting and caulking.

  The stator yokes 44A, 44B, 44C, 44G, 44H, 44I, and 44J are formed in a shape in which the peripheral surface portions 46A, 46B, 46C, 46G, 46H, 46I, and 46J do not have connection portions in the circumferential direction. Therefore, the leakage of magnetic flux is small and the closed state of the magnetic circuit is extremely good, and the torque of the drive motor 14 can be improved.

  Further, by forming each of the peripheral surface portions 46A to 46J in a cylindrical shape, the magnetic circuit can be closed and the magnetic circuit balance can be improved, and the reliability of the operation of the drive motor 14 can be improved. Moreover, when it forms in a cylindrical shape, there exists an advantage that a process is easy.

  In the above, portions that function as a magnetic balance holding portion, that is, a protrusion 47, a protrusion 47A, a hole 47B, a flat surface 47C, a protrusion 47D, a protrusion 47E, a protrusion 47F, a protrusion 47G, a protrusion 47H, Although an example in which only one protrusion 47I, one protrusion 47J, and one magnetic pin 52 are provided is shown, the portions that function as the magnetic balance holding portions are 180 ° opposite to each other across the rotation center of the magnet 41. Two may be provided at the position.

  The specific shapes and structures of the respective parts shown in the above-described best mode are merely examples of the implementation of the present invention, and the technical scope of the present invention is limited by these. It should not be interpreted in a general way.

2 to 29 show the best mode of the imaging apparatus and the drive motor of the present invention, and this figure is a conceptual diagram showing the basic configuration of the imaging apparatus. It is sectional drawing which shows the structural example of an imaging device. It is an enlarged rear view of a movable member. It is a disassembled perspective view which shows a moving mechanism and a drive motor. It is an expansion perspective view which shows a moving mechanism and a drive motor. It is an enlarged rear view of a drive motor. It is an expanded sectional view of a drive motor. It is an enlarged plan view of a drive motor. It is an enlarged front view of a drive motor. It is an expansion perspective view of a stator yoke. It is a conceptual diagram which shows the rotatable angle of a magnet. It is a wave form diagram which shows the detection state of a Hall element. It is a conceptual diagram which shows the state which has a magnet in a 1st rotation position. It is a conceptual diagram which shows the state which has a magnet in a 2nd rotation position. FIG. 16 shows the operation of the movable member together with FIG. 16, and is an enlarged rear view showing a state where the transmission hole is opened. It is an enlarged rear view which shows the state by which the penetration hole was obstruct | occluded. FIG. 18 and FIG. 29 show a modified example of the stator yoke, and this figure is an enlarged sectional view showing a first modified example of the stator yoke. It is an expansion perspective view which shows the example in which the protrusion was provided in the part except the both ends in the axial direction of a surrounding surface part in the 1st modification of a stator yoke. It is an expansion perspective view which shows the example in which the protrusion was provided in the part of the one side in the axial direction of a surrounding surface part in the 1st modification of a stator yoke. It is an expanded sectional view showing the 2nd modification of a stator yoke. It is an expanded sectional view showing the 3rd modification of a stator yoke. It is an expanded sectional view showing the 4th modification of a stator yoke. It is an expanded sectional view showing the 5th modification of a stator yoke. It is an expanded sectional view showing the 6th modification of a stator yoke. It is an expansion perspective view which shows the 7th modification of a stator yoke. It is an expansion perspective view which shows the 8th modification of a stator yoke. It is an expansion perspective view which shows the 9th modification of a stator yoke. It is an expansion perspective view which shows the 10th modification of a stator yoke. It is an expansion perspective view which shows the example to which the magnetic pin was attached by caulking in the 10th modification of a stator yoke.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Imaging device, 2 ... Lens barrel, 5 ... Moving mechanism, 6 ... Movable member, 7 ... Drive motor, 8 ... Imaging device, 9 ... Lens barrel, 13 ... Moving mechanism, 14 ... Drive motor, 26 ... Movable 27, a movable member, 35, a coil bobbin, 40, a shaft, 41, a magnet, 42, a rotating arm, 44, a stator yoke, 45, a stator coil, 46, a peripheral surface portion, 47, a projecting portion (magnetic balance holding portion). 49A Hall element (position detecting means) 44A Stator yoke 46A Peripheral surface portion 47A Projection (magnetic equilibrium holding portion) 44B Stator yoke 46B Peripheral surface portion 47B Hole (magnetic equilibrium holding portion) ), 44C... Stator yoke, 47C... Flat surface portion (magnetic balance holding portion), 51... Arc surface portion, 44D... Stator yoke, 46D. 44E ... Stator yoke, 46E ... circumferential surface portion, 47E ... Projection (magnetic balance holding portion), 44F ... Stator yoke, 46F ... Circumferential surface portion, 47F ... Projection (magnetic balance holding portion), 44G ... Stator yoke, 46G ... circumference Surface part, 47G ... Projection (magnetic balance holding part), 44H ... Stator yoke, 46H ... Peripheral surface part, 47H ... Projection (magnetic equilibrium holding part), 44I ... Stator yoke, 46I ... Peripheral surface part, 47I ... Projection (magnetic) Balance holding part), 44J ... stator yoke, 46J ... peripheral surface part, 52 ... magnetic pin (magnetic balance holding part)

Claims (14)

An imaging apparatus comprising: a lens barrel in which an imaging optical system is disposed; a moving mechanism having an iris or shutter, and a movable member that opens and closes an optical path of the imaging optical system; and a driving motor serving as a driving source of the moving mechanism Because
The drive motor is
A shaft that is the center of rotation;
A magnet that is two-pole magnetized and rotated about the shaft;
A rotating arm engaged with the movable member and rotated integrally with the magnet to move the movable member in a direction corresponding to the rotational direction;
A stator coil wound in a direction orthogonal to the magnet rotation direction and arranged to surround the magnet from the outside;
A coil bobbin around which the stator coil is wound;
A stator yoke having a cylindrical peripheral surface portion disposed outside the coil bobbin and penetrating in the axial direction of the shaft;
A position detecting means for detecting the rotational position of the magnet,
A closed magnetic path that is closed in the rotation direction of the magnet is formed by the peripheral surface portion of the stator yoke,
An imaging apparatus comprising: a stator yoke integrally formed with a magnetic balance holding portion that holds a magnetic balance between the magnet and the stator yoke when the stator coil is not energized. The imaging device according to claim 1, wherein a protrusion protruding from a peripheral surface portion is provided as the magnetic balance holding portion of the stator yoke. The imaging device according to claim 2, wherein the protrusion is protruded from the inner surface of the peripheral surface portion toward the coil bobbin. The imaging device according to claim 2, wherein the protrusion is protruded from the outer surface of the peripheral surface portion to the side opposite to the coil bobbin. The imaging device according to claim 1, wherein a hole or a notch is formed in a peripheral surface portion as the magnetic balance holding portion of the stator yoke. The said peripheral surface part of a stator yoke is comprised by the circular arc surface part and the plane part located between the both ends in the circumferential direction of this circular arc surface part, and this flat part was formed as a magnetic balance holding part. Imaging device. An imaging apparatus comprising: a lens barrel in which an imaging optical system is disposed; a moving mechanism having an iris or shutter, and a movable member that opens and closes an optical path of the imaging optical system; and a driving motor serving as a driving source of the moving mechanism Because
The drive motor is
A shaft that is the center of rotation;
A magnet that is two-pole magnetized and rotated about the shaft;
A rotating arm engaged with the movable member and rotated integrally with the magnet to move the movable member in a direction corresponding to the rotational direction;
A stator coil wound in a direction orthogonal to the magnet rotation direction and arranged to surround the magnet from the outside;
A coil bobbin around which the stator coil is wound;
A stator yoke having a cylindrical peripheral surface portion disposed outside the coil bobbin and penetrating in the axial direction of the shaft;
A position detecting means for detecting the rotational position of the magnet,
A closed magnetic path that is closed in the rotation direction of the magnet is formed by the peripheral surface portion of the stator yoke,
An image pickup apparatus comprising: a magnetic balance holding member for holding a magnetic balance between a magnet and a stator yoke when no power is supplied to the stator coil; A drive motor serving as a drive source for a moving mechanism that opens and closes an optical path of an image pickup optical system having a movable member constituting an iris or a shutter and disposed inside a lens barrel;
A shaft that is the center of rotation;
A magnet that is two-pole magnetized and rotated about the shaft;
A rotating arm engaged with the movable member and rotated integrally with the magnet to move the movable member in a direction corresponding to the rotational direction;
A stator coil wound in a direction orthogonal to the magnet rotation direction and arranged to surround the magnet from the outside;
A coil bobbin around which the stator coil is wound;
A stator yoke having a cylindrical peripheral surface portion disposed outside the coil bobbin and penetrating in the axial direction of the shaft;
A position detecting means for detecting the rotational position of the magnet,
A closed magnetic path that is closed in the rotation direction of the magnet is formed by the peripheral surface portion of the stator yoke,
A drive motor comprising a stator yoke integrally formed with a magnetic balance holding portion for holding a magnetic balance between the magnet and the stator yoke when the stator coil is not energized. The drive motor according to claim 8, wherein a protrusion protruding from a peripheral surface portion is provided as the magnetic balance holding portion of the stator yoke. The drive motor according to claim 9, wherein the protrusion is protruded from the inner surface of the peripheral surface portion toward the coil bobbin. The drive motor according to claim 9, wherein the protrusion is protruded from the outer surface of the peripheral surface portion to the side opposite to the coil bobbin. The drive motor according to claim 8, wherein a hole or a notch is formed in a peripheral surface portion as the magnetic balance holding portion of the stator yoke. The said circumferential surface part of a stator yoke is comprised by the circular arc surface part and the plane part located between the both ends in the circumferential direction of this circular arc surface part, and this planar part was formed as a magnetic balance holding part. Drive motor. A drive motor serving as a drive source for a moving mechanism that opens and closes an optical path of an image pickup optical system having a movable member constituting an iris or a shutter and disposed inside a lens barrel;
A shaft that is the center of rotation;
A magnet that is two-pole magnetized and rotated about the shaft;
A rotating arm engaged with the movable member and rotated integrally with the magnet to move the movable member in a direction corresponding to the rotational direction;
A stator coil wound in a direction orthogonal to the magnet rotation direction and arranged to surround the magnet from the outside;
A coil bobbin around which the stator coil is wound;
A stator yoke having a cylindrical peripheral surface portion disposed outside the coil bobbin and penetrating in the axial direction of the shaft;
A position detecting means for detecting the rotational position of the magnet,
A closed magnetic path that is closed in the rotation direction of the magnet is formed by the peripheral surface portion of the stator yoke,
A drive motor characterized in that a magnetic balance holding member that holds a magnetic balance between a magnet and a stator yoke when no power is supplied to the stator coil is attached to the inner surface of the stator yoke.

Images