JP4565323B2 - Imaging device and drive motor - Google Patents

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 improving torque and reducing the size 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. Inside the stator yoke, two pins formed of a ferromagnetic material are arranged apart from each other in the rotation direction of the magnet, and the output pin (rotation arm) rotated in accordance with the rotation of the magnet is the above 2. By being attracted to one of the two pins, the output pin is held at each moving end in the rotation direction.

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.

  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.

  Therefore, an object of the present invention is to overcome the above-described problems and to improve the torque and miniaturization of the drive motor.

In order to solve the above-described problems, the imaging device and the drive motor of the present invention are formed in a cylindrical shape and a cylindrical shape, and are magnetized in the N direction and the S pole in the circumferential direction. A magnet rotated in a direction, 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 rotating direction, and orthogonal to the rotating direction of the magnet A stator coil disposed so as to surround the magnet from the outside, a coil bobbin around which the stator coil is wound, and a substantially cylinder disposed outside the coil bobbin and penetrating in the axial direction of the shaft A stator yoke having a peripheral surface portion, and a closed magnetic path closed in the rotation direction of the magnet by the peripheral surface portion of the stator yoke, The protrusion that protrudes from the peripheral surface inwardly provided Tetayoku, of the magnet, the position of the movable member corresponds to the state of closing the optical path of the imaging optical system as a first rotational position, the magnet, the When the position corresponding to the state in which the movable member opens the optical path of the imaging optical system is set as the second rotation position, the protrusion is the N pole or S pole of the magnet corresponding to the first rotation position. It is provided at a position moved by a predetermined angle in the rotation direction opposite to the rotation direction to the second rotation position from the center position, and the projecting portion is located between the magnet and the stator yoke when the stator coil is not energized. A magnetic balance holding unit that holds a magnetic balance state, the magnetic balance holding unit is constituted by a continuous first portion and a second portion that approach from the peripheral surface portion toward the shaft, 1 part, of the magnet in the non-energization of the said stator coil than the second portion, is positioned at the front end side of the rotational direction opposite the rotational direction to said second rotational position, the first portion It is formed to be inclined at a predetermined angle with respect to a line segment extending radially from the rotation center of the shaft toward the continuous portion of the first portion and the second portion, and the second portion is formed from the rotation center of the shaft. The first portion and the second portion are formed so as to extend in the radial direction toward the continuous portion.

  Therefore, in the imaging device and the drive motor of the present invention, the magnetic equilibrium state between the magnet and the stator yoke when the stator coil is not energized is maintained by the magnetic equilibrium holding portion provided in the stator yoke. The

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 is formed in a cylindrical shape and is formed in a cylindrical shape, and is magnetized in the N and S poles in the circumferential direction, and rotates in the circumferential direction around the shaft. A movable arm that is engaged with the movable member and that rotates together with the magnet and moves the movable member in a direction corresponding to the rotational direction, and a direction orthogonal to the rotational direction of the magnet. A stator coil that is wound and surrounds 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 substantially cylindrical peripheral surface portion penetrating in the axial direction of the shaft, and a closed magnetic path closed in the rotation direction of the magnet by the peripheral surface portion of the stator yoke, and projecting inward from the peripheral surface portion to the stator yoke A position corresponding to a state where the movable member of the magnet closes the optical path of the imaging optical system is defined as a first rotation position, and the movable member of the magnet moves the optical path of the imaging optical system. When the position corresponding to the opened state is set as the second rotation position, the protrusion is more than the second position of the second pole than the center position of the N or S pole of the magnet corresponding to the first rotation position. It provided opposite to the rotating direction of the rotation position in the rotation direction by a predetermined angle movement position, the magnet and the stator yoke and the projections in the non-energization of the stator coils The magnetic balance holder is configured by a continuous first portion and a second portion that approach each other from the peripheral surface portion toward the shaft side. Is positioned on the tip side of the rotation direction opposite to the rotation direction to the second rotation position of the magnet when the stator coil is not energized from the second portion, and the first portion is the shaft The first portion and the second portion are formed to be inclined at a predetermined angle with respect to a line segment extending in the radial direction from the rotation center of the first portion to the continuous portion of the second portion. The first portion and the second portion are formed so as to extend in the radial direction toward a continuous portion.

  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, the protrusion functioning as the magnetic balance holding portion is formed such that the second portion extends in the radial direction from the rotation center of the shaft toward the continuous portion of the first portion and the second portion. Therefore, as compared with the case where the second part is inclined at a constant angle with respect to the line segment in the same manner as the first part, the length in the circumferential direction of the peripheral surface portion is increased, and the optical path of the imaging optical system is increased. Immediately before being blocked by the movable member, it is possible to prevent the disadvantage that the stator yoke and the magnet are magnetically balanced and the torque is suddenly reduced. Smooth movement is ensured and the reliability of the operation can be improved.

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. A shaft formed in a cylindrical shape, magnetized in the circumferential direction with N and S poles and rotated in the circumferential direction around the shaft, and 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 coil having a substantially cylindrical peripheral surface portion disposed outside the coil bobbin and penetrating in the axial direction of the shaft. And Tayoku, form a closed closed magnetic circuit in the rotation direction of the magnet by the peripheral surface of the stator yoke, the protruding portion that protrudes inward from the peripheral surface to the stator yoke provided in the magnet, the movable member is an imaging optical system When the position corresponding to the state in which the optical path is closed is the first rotational position, and the position of the magnet corresponding to the state in which the movable member opens the optical path of the imaging optical system is the second rotational position, The protrusion moves to a position that is moved by a predetermined angle in a rotation direction opposite to the rotation direction to the second rotation position from the center position of the N or S pole of the magnet corresponding to the first rotation position. provided, the projecting portion and magnetically magnetic balance holding unit for holding an equilibrium state between the magnet and the stator yoke in the non-energization of the stator coil, the magnetic equilibrium The holding portion is constituted by a continuous first portion and a second portion that approach from the peripheral surface portion toward the shaft, and the first portion is not energized from the second portion to the stator coil. The magnet is located on the tip side of the rotation direction opposite to the rotation direction to the second rotation position, and the first portion is directed from the rotation center of the shaft toward a continuous portion of the first portion and the second portion. The second part is inclined at a predetermined angle with respect to the line segment extending in the radial direction, and the second part extends along the radial direction from the rotation center of the shaft toward the continuous part of the first part and the second part. It is formed so that it may extend.

  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, the protrusion functioning as the magnetic balance holding portion is formed such that the second portion extends in the radial direction from the rotation center of the shaft toward the continuous portion of the first portion and the second portion. Therefore, as compared with the case where the second part is inclined at a constant angle with respect to the line segment in the same manner as the first part, the length in the circumferential direction of the peripheral surface portion is increased, and the optical path of the imaging optical system is increased. Immediately before being blocked by the movable member, it is possible to prevent the disadvantage that the stator yoke and the magnet are magnetically balanced and the torque is suddenly reduced. Smooth movement is ensured and the reliability of the operation can be improved.

  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 17).

  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 inputting.

  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 magnetized in the N and S poles in the circumferential direction. 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 integrally forming a peripheral surface portion 46 formed in a substantially cylindrical shape with a magnetic metal material and a protrusion 47 protruding inwardly from the peripheral surface portion 46. Become. 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 protrusion 47 is composed of a continuous first portion 47a and a second portion 47b that approach from the peripheral surface portion 46 toward the inside.

  The first portion 47a is positioned in the rotational direction of the rotor 39 when the stator coil 45 is not energized from the second portion 47b, that is, on the front end side in the CCW direction shown in FIGS.

  The second portion 47b is a line segment L (FIGS. 11 and 12) extending radially from the first portion 47a from the rotation center of the rotor 39 toward the continuous portion 47c of the first portion 47a and the second portion 47b. The inclination angle with respect to (see) is reduced. For example, the second portion 47b is formed to extend along the line segment L.

  The stator yoke 44 is positioned so as to be biased toward one end side 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 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, 50 ° (see FIGS. 11 to 13), and the opening edges of the arrangement holes 38 and 38 of the coil bobbin 35 function as a stopper for restricting the rotation of the rotor 39. To do. Accordingly, the rotation of the rotor 39 is restricted by the arm portions 42a, 42a of the rotating arm 42 contacting the opening edges of the arrangement holes 38, 38 at the rotation angles of 0 ° and 50 °, respectively.

  The hall element 49 is disposed at a position (center position) that is a half angle of the rotatable angle θ of the rotor 39, for example, at a position of 25 ° (see FIG. 13). The rotation 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. 14 schematically shows the detection level of the Hall element 49, and the horizontal line “V0” in the figure shows 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. 13, 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. 13, the detection level of the Hall element 49 gradually increases from a state below V0 as indicated by “gb”, and V0 is increased. 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 50 °, 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 50 °) in the rotation angle is a second rotation position (see FIG. 12) 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. 11, the protrusion 47 of the stator yoke 44 is set at a position in the vicinity of 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. 12, 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 in the circumferential direction of the S pole (see FIG. 11) in 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. 13 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 pivot arm 42 is rotated in the counterclockwise direction (CCW) shown in FIG. 13, 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 the magnetic balance holder is provided, the number of parts can be reduced as compared with the case where a separate member is provided as the magnetic balance holder, and the arrangement of the magnetic balance holder is also provided. Since the space is small, the size can be reduced.

  Further, the protrusion 47 functioning as a magnetic balance holding portion has a line segment L than the first portion 47a positioned on the front end side in the rotation direction of the rotor 39 when the second portion 47b is not energized to the stator coil 45. Since the inclination angle with respect to is small, the circumferential direction of the peripheral surface portion 46 is larger than when the second portion is gently inclined at a constant angle with respect to the line segment L as in the first portion 47a. The length at becomes longer.

  Accordingly, the stator yoke and the magnet 41 are magnetically magnetically just before the opening 50 is closed by the movable members 26 and 27, as in the case where the second portion is formed longer in the circumferential direction of the peripheral surface portion 46. It is possible to prevent the inconvenience that the torque rapidly decreases in proportion to the balance, and the so-called return torque when the stator coil 45 is de-energized is improved, and the smooth movement of the movable members 26 and 27 is ensured and the operation reliability is improved. Improvements can be made.

  The graph of FIG. 17 shows the return torque at each rotation angle of the rotor in comparison with the conventional drive motor and the drive motor 14 according to the present invention.

  As shown in FIG. 17, the conventional protrusion has a long length in the circumferential direction, and the protrusion amount F <b> 1 from the peripheral surface portion is the same as the protrusion amount F <b> 2 of the protrusion 47 from the peripheral surface portion 46. Has been.

  As shown in FIG. 17, the return torque in the present invention is larger than the conventional return torque at the angle of rotation end (50 °) (see B shown in FIG. 17). The rotation angle of the rotor 39 is larger than the conventional angle because the circumferential length of the peripheral surface portion 46 is longer than the conventional one.

  In the above, an example in which only one protrusion 47 is provided as a part that functions as a magnetic balance holder, but these parts that function as a magnetic balance holder sandwich the rotation center of the magnet 41, respectively. However, two may be provided in a point-symmetric state at positions opposite to each other by 180 °.

  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.

FIG. 2 to FIG. 17 show the best mode of the imaging device and the drive motor of the present invention, and this diagram is a conceptual diagram showing the basic configuration of the imaging device. 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 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. 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. FIG. 16 shows the operation of the movable member together with FIG. 16, and is an enlarged rear view showing a state in which the transmission hole is opened. It is an enlarged rear view which shows the state by which the penetration hole was obstruct | occluded. It is a graph which shows the return torque in each rotation angle of a rotor by comparing with the conventional drive motor and the drive motor which concerns on this invention.

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, movable member, 35 ... coil bobbin, 40 ... shaft, 41 ... magnet, 42 ... rotating arm, 44 ... stator yoke, 45 ... stator coil, 46 ... peripheral surface portion, 47 ... protrusion (magnetic balance holding portion) 47a ... first part, 47b ... second part, 47c ... continuous part

Claims (2)

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 which is formed in a cylindrical shape and is magnetized in the N and S poles in the circumferential direction and rotated in the circumferential direction around 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 substantially cylindrical circumferential surface portion disposed outside the coil bobbin and penetrating in the axial direction of the shaft;
Forming a closed magnetic path closed in the rotation direction of the magnet by the peripheral surface portion of the stator yoke;
The stator yoke is provided with a protrusion protruding inward from the peripheral surface portion,
A position of the magnet corresponding to a state where the movable member closes the optical path of the imaging optical system is defined as a first rotation position, and a position of the magnet corresponding to a state where the movable member opens the optical path of the imaging optical system Is the second rotational position, and the projecting portion has a rotational direction to the second rotational position rather than the center position of the N or S pole of the magnet corresponding to the first rotational position. Provided at a position moved by a predetermined angle in the opposite direction of rotation,
The protrusion is a magnetic equilibrium holding portion that holds a magnetic equilibrium state between the magnet and the stator yoke when the stator coil is not energized,
The magnetic balance holder is constituted by a continuous first portion and a second portion that approach from the peripheral surface portion toward the shaft side,
The first portion is located on the tip side of the rotation direction opposite to the rotation direction to the second rotation position of the magnet when the stator coil is not energized from the second portion,
The first portion is formed to be inclined at a predetermined angle with respect to a line segment extending radially from the rotation center of the shaft toward a continuous portion of the first portion and the second portion,
The second part is formed so as to extend in a radial direction from a rotation center of the shaft toward a continuous part of the first part and the second part. 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 which is formed in a cylindrical shape and is magnetized in the N and S poles in the circumferential direction and rotated in the circumferential direction around 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 substantially cylindrical peripheral surface portion disposed outside the coil bobbin and penetrating in the axial direction of the shaft;
Forming a closed magnetic path closed in the rotation direction of the magnet by the peripheral surface portion of the stator yoke;
The stator yoke is provided with a protrusion protruding inward from the peripheral surface portion,
A position of the magnet corresponding to a state where the movable member closes the optical path of the imaging optical system is defined as a first rotation position, and a position of the magnet corresponding to a state where the movable member opens the optical path of the imaging optical system Is the second rotational position, and the projecting portion has a rotational direction to the second rotational position rather than the center position of the N or S pole of the magnet corresponding to the first rotational position. Provided at a position moved by a predetermined angle in the opposite rotational direction,
The protrusion is a magnetic equilibrium holding portion that holds a magnetic equilibrium state between the magnet and the stator yoke when the stator coil is not energized,
The magnetic balance maintaining part is constituted by a continuous first part and a second part that approach the shaft side from the peripheral surface part,
The first portion is located on the tip side of the rotation direction opposite to the rotation direction to the second rotation position of the magnet when the stator coil is not energized from the second portion,
The first portion is formed to be inclined at a predetermined angle with respect to a line segment extending radially from the rotation center of the shaft toward a continuous portion of the first portion and the second portion,
The drive motor, wherein the second part is formed to extend in a radial direction from a rotation center of the shaft toward a continuous part of the first part and the second part.

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