JP2013003433A - Actuator, lens barrel, and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an actuator having a function of self-holding a stop position.SOLUTION: The actuator includes a movable element and a stator and furthermore includes a multi-pole magnet disposed in one of the movable element and the stator, a plurality of coils disposed in the other of the movable element and the stator so as to face the multi-pole magnet, and an urging mechanism which urges the stator and the movable element in contact with each other or urges them away from each other. The multi-pole magnet and the coils output first thrust which moves the movable element along a plane where the plurality of coils are arranged, relative to stator and second thrust which brings the stator away from or into contact with the movable element against urging of the urging mechanism.

Description

  The present invention relates to an actuator, a lens barrel, and an imaging device.

There is an imaging apparatus that moves a lens by a linear actuator having a magnet and a coil (see Patent Document 1).
[Prior art documents]
[Patent Literature]
[Patent Document 1] Japanese Patent Application Laid-Open No. 2004-191453

  The linear actuator can maintain the position of the stopped mover by feedback control based on the position of the mover. However, power is consumed even during periods when the mover is not moving. Further, when the power is cut off, the linear actuator cannot maintain the position of the mover.

  Therefore, in order to solve the above-mentioned problem, as a first aspect of the present invention, an actuator including a mover and a stator, a multipolar magnet disposed on one of the mover and the stator, the mover and the fixed A plurality of coils arranged opposite to the multi-pole magnet and a biasing mechanism that biases the stator and the movable element in contact with each other or biases them in a direction away from each other. The multipolar magnet and the coil have a first thrust that moves the mover relative to the stator along a plane on which the plurality of coils are arranged, and the mover against the bias of the biasing mechanism. An actuator is provided that outputs a second thrust that is spaced apart from or in contact with.

  As a second aspect of the present invention, a lens barrel including the actuator is provided. Furthermore, as a third aspect of the present invention, an imaging apparatus including the lens barrel is provided.

  The above summary of the present invention does not enumerate all necessary features of the present invention. Sub-combinations of these feature groups can also be an invention.

2 is a perspective view of an actuator 100. FIG. 3 is a horizontal sectional view of a driving unit 248 and a driven unit 328. FIG. 4 is a side view of a driving unit 248 and a driven unit 328. FIG. 2 is a vertical sectional view of an actuator 100. FIG. 2 is a vertical sectional view of an actuator 100. FIG. 2 is a block diagram showing an electrical structure of an actuator 100. FIG. It is a graph which shows the waveform of the drive current which concerns on a 1st thrust. It is a graph which shows the waveform of the drive current which concerns on a 2nd thrust. 2 is a vertical sectional view of an actuator 100. FIG. 2 is a vertical sectional view of an actuator 101. FIG. 2 is a schematic cross-sectional view of a single-lens reflex camera 500. FIG.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1 is a perspective view of the actuator 100. The actuator 100 includes a stator 200 that is fixed to the device and a mover 300 that moves relative to the stator 200.

  The stator 200 includes a base 210, a support portion 220, a guide bar 230, and a swinging portion 240. The base 210 is rectangular, and a position sensor 212 used for detecting the position of a mover 300 described later is arranged in parallel with the longitudinal direction.

  The support part 220 rises vertically in parallel with each other from both longitudinal ends of the base 210. The support part 220 has an opening 222 that allows incident light and outgoing light to the lens 310 to be described later to pass therethrough. In each of the pair of support portions 220, the end portions of the lens frame stopper 224, the guide bar 230, and the swinging portion 240 are supported around the openings 222 on the surfaces facing each other.

  The pair of guide bars 230 are fixed to the support part 220 at both ends. Accordingly, the guide bars 230 are arranged in parallel to each other and in parallel to the base 210.

  The lens frame stopper 224 protrudes from the mutually opposing surfaces of the support part 220 toward the other support part 220 in parallel with the guide bar 230. By abutting the tip of the lens frame stopper 224, one end of the movement range of the lens frame 320 described later is defined.

  The swinging parts 240 are arranged opposite to each other at positions symmetrical to the opening 222. Each of the swinging parts 240 is supported swingably from the support part 220 via a swinging shaft 242 provided at one end in the height direction.

  In the example shown in the drawing, the rocking portion 240 on the near side in the drawing is provided with a rocking shaft 242 at the lower end thereof. Therefore, when the swinging portion 240 swings, the upper end of the swinging portion 240 is displaced in the radial direction of the opening 222. Further, in the drawing, the rocker 240 on the back side is provided with a rocking shaft 242 at the upper end thereof. Therefore, when the swinging portion 240 swings, the lower end of the swinging portion 240 is displaced in the radial direction of the opening 222.

  However, the swing range of each swing portion 240 is limited by the swing portion stopper 226 disposed on the support portion 220 outside the swing portion 240 in the radial direction of the opening 222. Further, the end of the swinging portion 240 that is displaced when swinging is coupled to the lens frame stopper 224 by the biasing member 250.

  The lens frame stopper 224 is disposed around the opening 222 on the side farther from the swing shaft 242 with respect to the swing portion 240. Further, the urging member 250 is urged in a direction in which the length of the urging member 250 contracts. Therefore, one end of the swinging portion 240 is biased inward in the radial direction of the opening 222.

  The mover 300 includes a lens 310, a lens frame 320, and a driven unit cover 330. The lens frame 320 holds the lens 310 between the pair of openings 222.

  A guided portion 322 is attached to a part of the outer periphery of the lens frame 320. The guided portion 322 has a fitting hole 321 through which the guide bar 230 is inserted. The fitting hole 321 has substantially the same shape and size as the outer diameter of the guide bar 230. Thus, the lens 310, the lens frame 320, and the guided portion 322 are supported from the guide bar 230 so as to be slidable in the longitudinal direction of the guide bar 230.

  Note that a pair of driven parts 328 are arranged on the side part of the lens frame 320 instead of the guided part 322. However, in the illustrated state, the driven part 328 is covered with the driven part cover 330. Therefore, the driven portion 328 will be described with reference to other drawings.

  FIG. 2 is a horizontal cross-sectional view showing the structure of the drive unit 248 formed on the swinging unit 240 and the driven unit 328 formed on the mover 300. FIG. 2 shows a state where the oscillating portion 240 on one side in FIG. 1 is cut by a horizontal surface in the middle in the height direction. In FIG. 2, the same elements as those in FIG.

  In the swing part 240, a plurality of drive coils 244 arranged in the longitudinal direction of the swing part 240 form a drive part 248. The drive coils 244 have the same size and number of turns.

In the mover 300, a plurality of permanent magnets 340 arranged in a direction parallel to the arrangement direction of the drive coils 244 form a driven part 328. Permanent magnet 340 has a width equal to each other in the longitudinal direction of the oscillating portion 240, a magnetic pattern having a constant magnetic pole pitch P ₁ forms a magnetized with multipolar magnets. In addition to magnetizing the magnetic pattern, the multipolar magnet can be formed by laminating a single magnet.

The drive coil 244 and the permanent magnet 340 are arranged to face each other with a constant interval. In the case of the magnet and coil arrangement as shown in FIG. 2, the magnetic pole pitch P ₁ between the same poles of the permanent magnet 340 in the driven portion 328 is larger than the arrangement pitch P ₂ of the drive coil 244.

  FIG. 3 is a schematic side view of the drive unit 248 and the driven unit 328 shown in FIG. In FIG. 3, the same elements as those in FIGS. 1 and 2 are denoted by the same reference numerals, and redundant description is omitted.

  In the drive unit 248, each of the drive coils 244 is wound around a core parallel to the paper surface. As a result, when a drive current is passed through each of the drive coils 244, a magnetic flux that circulates between the inside and the outside of each of the drive coils 244 is generated to form a magnetic field.

  The magnetic field generated by the drive coil 244 interacts with the permanent magnet 340 having a specific magnetic pattern. However, the direction of the interaction between the magnetic field of the drive coil 244 and the permanent magnet 340 differs depending on the positional relationship between the two.

  FIG. 4 is a vertical cross-sectional view of the actuator 100, and shows a vertical cross-section of the stator 200 that does not include the mover 300. Elements common to FIGS. 1 to 3 are denoted by the same reference numerals, and redundant description is omitted.

  As already described, each of the swinging parts 240 swings with respect to the base 210 with respect to the swinging shaft 242. Further, the end of each swinging portion 240 opposite to the swinging shaft 242 is biased toward the center of the opening 222 by a biasing member 250 as shown. Note that a high friction material layer 246 is disposed at one end of the swinging portion 240. The role of the high friction material layer 246 will be described later.

  FIG. 5 is another vertical cross-sectional view of the actuator 100 and shows a cross section cut by a plane including the mover 300. Elements that are the same as those in FIG. 4 are given the same reference numerals, and redundant descriptions are omitted.

  In the cross section shown in FIG. 5, it can be seen that the permanent magnet 340 provided with the yoke 342 faces the drive coil 244. In addition, the structure of the guided portion 322 arranged on the lower outer periphery of the lens frame 320 appears. A position index 324 is disposed on the lower surface of the lower guided portion 322. The position index 324 moves together with the mover 300 while facing the position sensor 212 disposed on the upper surface of the base 210.

  The position index 324 can be formed by a magnetized magnetic material, for example. Further, the position sensor 212 can be formed by a Hall element array having a plurality of Hall elements arranged in the longitudinal direction of the substrate 210. Further, the position index 324 may be a linear scale, and the position sensor 212 may be a linear encoder.

  Further, in the movable member 300 having the cross section shown in FIG. 4, it can be seen that the lower guide bar 230 is inserted into the elongated hole 323 of the guided portion 322. Thereby, it is suppressed that the lens frame 320 rotates around the upper guide bar 230. However, the sliding of the lens frame 320 along the guide bar 230 is not hindered by fluctuations in the distance between the guide bars 230 or the like.

  In the actuator 100 having the above-described structure, the end opposite to the swing shaft 242 of each swing portion 240 is attached toward the center of the lens 310 by the biasing member 250 as described above. It is energized. Thereby, one end of the swinging part 240 is pressed against a part of the lens frame 320.

  In the illustrated example, the upper end of the right swinging portion 240 is urged by the urging member 250 in a state where the upper end of the oscillating portion 240 is in contact with the outer peripheral surface of the lens frame 320. Further, the lower end of the left swinging portion 240 is biased by the biasing member 250 in a state where the lower end of the swinging portion 240 is in contact with the outer peripheral surface of the lens frame 320.

  Therefore, the movement of the lens frame 320 along the guide bar 230 is hindered by the frictional force between the swinging portion 240 and the lens frame 320. Therefore, when the driving force is not applied to the mover 300, the position of the stopped mover 300 in the direction along the guide bar 230 is held by the swinging unit 240.

  In view of the above effects, the surface of the swinging part 240 that contacts the lens frame 320 and the region of the lens frame 320 that contacts the swinging part 240 are each a high friction material layer having a high friction coefficient. It is preferable to have 246, 326 on the surface. Alternatively, the surface texture of the surface and the region may be roughened to increase the friction coefficient of the surface. Thereby, the stationary position of the needle | mover 300 can be hold | maintained reliably.

  FIG. 6 is a block diagram showing the electrical structure of the actuator 100. The actuator 100 includes a drive control unit 400 having a position calculation unit 410, a calculation unit 420, and a three-phase command generation unit 430.

  The position calculation unit 410 calculates the position of the mover 300 from the pulse signal detected by the position sensor 212 as the position index 324 moves. When the target position is input, the calculation unit 420 refers to the position of the mover 300 calculated by the position calculation unit 410 and determines the driving amount according to the distance to the target position and the direction of the mover 300. .

  Three-phase command generator 430 generates a drive current to be supplied to drive coil 244 based on the instruction received from calculation unit 420. Here, the three-phase command generation unit 430 has two systems of an axial direction thrust command generation unit 432 and a radial direction thrust command generation unit 434. The axial direction thrust command generator 432 and the radial direction thrust command generator 434 individually generate U-phase, V-phase, and W-phase drive currents.

  The plurality of drive coils 244 are individually wound and then connected to three phases of the U phase, the V phase, and the W phase. The axial direction thrust command and the radial direction command generated by the axial direction thrust command generation unit 432 and the radial direction thrust command generation unit 434, respectively, are added and amplified and supplied to the plurality of drive coils 244 as a drive current. As a result, the drive coil 244 generates a first thrust and a second thrust.

  In the example shown in the figure, three sets of three phases of the U phase, the V phase, and the W phase are shown. Further, the connection of the drive coil 244 is not limited to the three-phase connection, but may be a three-phase or more or two-phase connection. Furthermore, each of the drive coils 244 may be provided with a current detection resistor 245 for the purpose of current control or detection of overcurrent.

  FIG. 7 is a graph showing the waveform of the axial drive current that causes the axial thrust command generator 432 to generate the first thrust in the drive coil 244 over time. As illustrated, the axial direction thrust command generator 432 supplies a three-phase axial direction drive current of U phase, V phase, and W phase to the drive coil 244. The axial drive current of each phase changes periodically in a sine wave shape. Such a phase of the axial drive current corresponds to the position of the mover 300 calculated by the position calculation unit 410.

  Further, the axial drive currents of the respective phases are out of phase with each other by 1/3 period. Thereby, the permanent magnet 340 of the mover 300 attracts the magnetic field generated by the preceding drive coil 244 in the traveling direction of the mover 300 and repels the rear drive coil 244 in the traveling direction. Therefore, a first thrust for moving the mover 300 along the plane in which the drive coils 244 are arranged is generated. Thus, the axial direction thrust command generator 432 supplies the axial direction drive current that generates the first thrust between the drive coil 244 and the permanent magnet 340.

  FIG. 8 is a graph showing the waveform of the radial drive current that causes the radial thrust command generator 434 to generate the second thrust in the drive coil 244. A sine wave indicated by a dotted line in the figure is the W phase of the three-phase axial drive currents of the U phase, the V phase, and the W phase generated by the axial thrust command generation unit 432.

In contrast, radial thrust command generating unit 434, with respect to the axial direction drive current, 1/4 pitch of the pole pitch P ₁ of the permanent magnet 340, generates a radial drive current whose phase is delayed. The radial thrust command generator 434 generates a three-phase radial drive current corresponding to each of the U-phase, V-phase, and W-phase axial drive currents.

  Each of the drive coils 244 supplied with the radial drive current whose phase is shifted by 1/4 pitch from the axial drive current generates a magnetic field in the same manner as when the axial drive current is supplied. However, the relative position of the permanent magnet 340 with respect to the magnetic field generated by the radial drive current by the drive coil 244 is different from the relative position with respect to the magnetic field generated by the axial drive current.

  For this reason, the magnetic field generated by the radial drive current does not contribute to the generation of axial thrust on the permanent magnet 340. In addition, among the magnetic fluxes that form the magnetic field, the magnetic flux that is orthogonal to the axial direction of the guide bar 230 acts predominantly on the permanent magnet 340.

  Therefore, a repulsive force that swings the swinging portion 240 against the biasing force of the biasing member 250 is generated between the magnetic field generated in the drive coil 244 by the radial driving current and the permanent magnet 340. This repulsive force is a second thrust that separates the high friction material layer 246 of the swinging portion 240 from the lens frame 320.

  As described above, the radial thrust command generation unit 434 supplies the drive coil 244 with a radial drive current that generates the second thrust between the drive coil 244 and the permanent magnet 340. The second thrust causes the oscillating portion 240 to oscillate to separate the oscillating portion 240 and the lens frame 320 from each other, thereby making the movable element 300 movable relative to the guide bar 230.

  FIG. 9 is a cross-sectional view showing the swinging portion 240 when the second thrust is applied. FIG. 9 is drawn from the same viewpoint as FIG.

  When a second thrust is generated between the drive coil 244 and the permanent magnet 340, the swinging part 240 swings against the biasing force of the biasing member 250. As a result, the swinging part 240 is separated from the lens frame 320, so that friction between the swinging part 240 and the lens frame 320 is eliminated. Therefore, the mover 300 can slide smoothly along the guide bar 230.

  When the swinging swinging portion 240 abuts on the swinging portion stopper 226, further swinging is restricted. Therefore, the extended tip of the swinging portion 240 does not come into contact with the driven portion cover 330 on the movable element 300 side and does not hinder the movement of the movable element 300.

  As already described, the drive coil 244 is also supplied with an axial drive current. As a result, a first thrust acting in the axial direction of the guide bar 230 is also generated between the drive coil 244 and the permanent magnet 340. Therefore, the mover 300 moves along the plane in which the drive coils 244 are arranged by the first thrust.

  As described above, while the radial drive current is supplied from the drive control unit 400, the braking of the movable member 300 by the swinging portion 240 is released by the second thrust, and further, the movable member is moved by the first thrust. Moves smoothly in the axial direction. As a result, the lens frame 320 and the lens 310 held by the lens frame 320 move.

  In addition, when the supply of the axial drive current from the drive control unit 400 is cut off, the first thrust disappears, so that the mover 300 decreases in speed due to the sliding friction between the guide bar 230 and the guided portion 322. Then head to the stop state. Further, when the supply of the radial driving current is cut off, the second thrust disappears, so that the swinging portion 240 swings and contacts the lens frame 320 by the action of the biasing member 250. Thereby, the stationary position of the needle | mover 300 is hold | maintained.

  Note that each of the drive coils 244 may be provided with a short brake switch that electrically couples both ends thereof. Thereby, when the switch is turned on when the mover 300 is stopped, the counter electromotive force generated in the drive coil 244 moving with respect to the permanent magnet 340 immediately stops the movable unit 300.

  The magnetic field generated by the axial direction drive current and the radial direction drive current may interact with each other, and the first thrust or the second thrust may vary as the mover 300 moves. In such a case, the calculation unit 420 may correct the instruction to the three-phase command generation unit 430 so as to keep at least one of the first thrust and the second thrust constant.

  That is, the characteristics of the magnetic field generated by the drive coil 244 by the axial direction drive current and the radial direction drive current are known in advance. Therefore, any thrust can be stabilized by correcting the command according to the position of the mover 300 calculated by the position calculation unit 410.

  In the above example, the permanent magnet 340 is disposed on the mover 300, and the drive coil 244 is disposed on the swinging portion 240. However, even if the drive coil 244 is arranged on the mover 300 and the permanent magnet 340 is arranged on the swing part 240, the actuator 100 having the same function can be formed.

  Furthermore, in the above example, the urging member 250 urges the oscillating portion 240 radially inward, and the oscillating portion 240 grips the lens frame 320. However, the same function as that of the actuator 100 is realized even in a structure in which the swinging part 240 is urged radially outward and the swinging part 240 comes into contact with the driven part cover 330 to brake the movable element 300. it can.

  Furthermore, in the above example, the urging member 250 has a structure that urges the oscillating portion 240 in a direction in which the oscillating portion 240 and the lens frame 320 are in contact with each other. However, depending on the application, when the radial driving current is supplied, the movable body 300 may be braked by the second thrust. Thereby, the stop position of the needle | mover 300 can be controlled with high precision.

  FIG. 10 is a cross-sectional view of an actuator 101 having another structure and is drawn from the same viewpoint and state as FIG. The actuator 101 has the same structure as the actuator 100 already described, except for the parts described below. Therefore, the same reference numerals are assigned to elements common to the actuator 100, and redundant description is omitted.

  The actuator 101 has a unique structure in that the biasing member 250 is omitted and the high magnetic material layer 247 is provided on the inner surface of the swinging portion 240. In the example shown in the drawing, the high magnetic material layer 247 is arranged inside each drive coil 244 and faces the permanent magnet 340.

  Since the magnetic force of the permanent magnet 340 of the mover 300 acts on the high magnetic material layer 247, the swinging part 240 is attracted to the lens frame 320. Thereby, the rocking | swiveling part 240 and the lens frame 320 contact, and the movement of the needle | mover 300 is controlled. Thus, the actuator 101 can hold the position of the mover 300 by the swinging portion 240 without using the biasing member 250.

  Further, as already described, when the radial thrust command generator 434 supplies the radial drive current to the drive coil 244, a repulsive force is generated between the drive coil 244 and the permanent magnet 340. As a result, the swinging portion 240 that has been attracted to the permanent magnet 340 is separated from the lens frame 320, so that the mover 300 can move smoothly. In this state, when the axial direction thrust command generation unit 432 supplies the axial direction drive current, the mover 300 moves smoothly.

  In addition, the attractive force with respect to the rocking | swiveling part 240 by the magnetic force of the permanent magnet 340 is inversely proportional to the square of the distance between the permanent magnet 340 and the high magnetic material layer 247. Therefore, if the swinging portion 240 starts to move away from the permanent magnet 340 even by a small amount due to the second thrust, the attracting force by the permanent magnet 340 decreases rapidly.

  Therefore, if the swinging part 240 starts to move away from the lens frame 320, the movable element 300 can be kept released from the braking state even if the radial driving current is decreased to weaken the second thrust. As a result, the radial drive current generated by the radial thrust command generator 434 can be reduced, and the power consumption of the actuator 101 can be saved.

  Further, as described above, the attractive force due to the magnetic force of the permanent magnet 340 is extremely high when the object to be attracted is in contact with the permanent magnet 340. Therefore, if there is a portion of the swinging portion 240 that comes into contact with the permanent magnet 340, the swinging portion 240 can be brought into strong contact with the lens frame 320 by providing the high magnetic material layer 247 at the contact portion. it can.

  FIG. 11 is a schematic cross-sectional view of a single-lens reflex camera 500. The single-lens reflex camera 500 includes a lens barrel 600 and a camera body 700.

  The lens barrel 600 includes a fixed barrel 610 and lenses 620, 630, and 640. The rear end of the fixed barrel 610 is coupled to the body mount 750 of the camera body 700 via the lens mount 650. The coupling of the lens mount 650 and the body mount 750 can be released by a specific operation. Thus, another lens barrel 600 having the same lens mount 650 can be attached to the camera body 700.

  In the lens barrel 600, the lens 620 farthest from the camera body 700 is directly supported from the fixed barrel 610. On the other hand, the other lenses 630 and 640 are supported by the lens frame 320 that moves relative to the fixed cylinder 610.

  That is, the lenses 630 and 640 are held by the independent lens frame 320, respectively. Each of the lens frames 320 is provided with a guided portion 322 on the outer periphery thereof. Further, the guided portion 322 is inserted through a pair of guide bars 230 fixed to the fixed cylinder 610, and slides while being guided by the guide bars 230 in the longitudinal direction of the lens barrel 600.

  Although not shown in the cross-sectional view, swinging portions 240 each having a drive coil 244 are disposed on the front side and the back side with respect to the paper surface of the fixed cylinder 610. Further, permanent magnets 340 are disposed on the front side and the back side of the lens frame 320, respectively.

  Thereby, the actuator 100 having the first movable element 301 including the lens frame 320 holding the lens 630 and the second movable element 302 including the lens frame 320 holding the lens 630 is formed in the lens barrel 600. Is done. In the following, elements common to the actuator 100 shown up to FIG. 9 are assigned the same reference numerals, and redundant description is omitted.

  A position index 324 is individually attached to the bottom of each guided portion 322. A position sensor 212 is disposed on the bottom surface of the fixed cylinder 610. Therefore, the position calculation unit 410 can individually calculate the positions of the first movable element 301 and the second movable element 302. Further, the three-phase command generation unit 430 generates the first axial drive current including two sets of three-phase drive currents each generating the first thrust based on the calculated position information, thereby The mover 301 and the second mover 302 are moved individually.

  The drive control unit 400 continues to generate the second thrust that causes the swinging unit 240 to swing while either one of the first mover 301 or the second mover 302 is moving, When both the first movable element 301 and the second movable element 302 are stopped, the second thrust is also stopped. Thereby, even if a power supply is interrupted | blocked, the stop position of the 1st needle | mover 301 and the 2nd needle | mover 302 is hold | maintained.

  The lens 630 can be one of zoom lenses that move when the magnification of the lens barrel 600 is changed. The lens 640 may be one of focusing lenses that move when the focal position of the lens barrel 600 is changed.

  The camera body 700 includes a main mirror 720 and a sub mirror 722 inside the housing 710 behind the body mount 750 with respect to the lens barrel 600. Further, a focusing optical system 730 is provided below the main mirror 720, and a focusing plate 742 is provided above the main mirror 720, respectively. A pentaprism 744 and a viewfinder optical system 746 are disposed further above the focus plate 742.

  Further, behind the main mirror 720, a focal plane shutter 790, a low-pass filter 782, and an image sensor 780 are sequentially arranged. Behind the image sensor 780, a main board 770 on which a system control unit 772, an image processing unit 774, and the like are mounted is disposed.

  The main mirror 720 is held by the main mirror holding frame 721. The main mirror holding frame 721 is pivotally supported from the housing 710 via the main mirror swinging shaft 723. The sub mirror 722 is held by the sub mirror holding frame 727. The sub mirror holding frame 727 is pivotally supported on the lower surface side of the main mirror holding frame 721 via a sub mirror swinging shaft 729.

  The main mirror 720 oscillates between an obliquely arranged state inclined on the optical path of the subject light beam incident from the lens barrel 600 and a retreat position that rises while avoiding the subject light beam. The main mirror 720 in the oblique state reflects most of the incident light toward the focus plate 742. The focus plate 742 is arranged at a position where an image is formed when the lenses 620, 630, and 640 of the lens barrel 600 are in focus, and visualizes the image.

  The image formed on the focus plate 742 is observed from the finder optical system 746 via the pentaprism 744. By passing the pentaprism 744, the finder optical system 746 can see the image on the focusing screen 742 as an erect image.

  The main mirror 720 has a half mirror region that transmits a part of incident light. As a result, the sub mirror 722 receives a part of the subject luminous flux and reflects it toward the focusing optical system 730. The focusing optical system 730 guides a part of the incident subject luminous flux to the focusing sensor. Thereby, the camera body 700 can determine the target position of the movable element 301 when the lens barrel 600 is focused.

  Note that, when the main mirror 720 is lifted into the retracted state, the sub mirror 722 is also retracted from the optical path of the subject light flux. Therefore, the incident subject luminous flux is directly incident on the focal plane shutter 790. Further, when the focal plane shutter 790 is open, the subject luminous flux passes through the low-pass filter 782 and then enters the image sensor 780.

  The image sensor 780 is formed by a photoelectric conversion element such as a CCD sensor or a CMOS sensor. The image sensor 780 converts the received subject image into an electrical signal and outputs it. The electric signal output from the image sensor 780 is converted into image data in the image processing unit 774. Thus, image data corresponding to the subject luminous flux is acquired. A system control unit 772 mounted on the main substrate 770 together with the image processing unit 774 controls an operation sequence of the main mirror 720, the sub mirror 722, the focal plane shutter 790, and the like.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

100, 101 Actuator, 200 Stator, 210 Base, 212 Position sensor, 220 Support part, 222 Opening, 224 Lens frame stopper, 226 Swing part stopper, 230 Guide bar, 240 Swing part, 242 Swing axis, 244 Drive Coil, 245 Current detection resistance, 246, 326 High friction material layer, 247 High magnetic material layer, 248 Drive unit, 250 Energizing member, 300, 301, 302 Movable element, 310 Lens, 320 Lens frame, 321 Fitting hole 322 Guided part, 323 slot, 324 Position indicator, 328 Driven part, 330 Driven part cover, 340 Permanent magnet, 342 Yoke, 400 Drive control part, 410 Position calculation part, 420 Calculation part, 430 Three-phase command Generation unit, 432 Axial direction thrust command generation unit, 434 Radial direction thrust command generation , 500 single-lens reflex camera, 600 lens barrel, 610 fixed barrel, 620, 630, 640 lens, 650 lens mount, 700 camera body, 710 housing, 720 main mirror, 721 main mirror holding frame, 722 sub mirror, 723, 729 Oscillating shaft, 727 Sub mirror holding frame, 730 Focusing optical system, 742 Focus plate, 744 Pentaprism, 746 Finder optical system, 750 Body mount, 770 Main substrate, 772 Control unit, 774 Image processing unit, 780 Image sensor, 782 Low pass filter, 790 focal plane shutter

Claims (13)

An actuator comprising a mover and a stator,
A multipole magnet disposed on one of the mover and the stator;
A plurality of coils arranged on the other side of the mover and the stator so as to face the multipolar magnet;
An urging mechanism for urging the stator and the mover in contact with each other, or urging the stator and the mover in directions away from each other;
The multi-pole magnet and the plurality of coils include a first thrust that moves the mover relative to the stator along a plane on which the plurality of coils are disposed, and the stator of the biasing mechanism. An actuator that outputs a second thrust force that moves away from or comes into contact with the movable element against an urging force.   The actuator according to claim 1, wherein the urging mechanism prevents the mover from moving when the plurality of coils are not supplied with power by bringing the stator and the mover into contact with each other.   The actuator according to claim 1, further comprising a control circuit that supplies power to the plurality of coils to output the first thrust and the second thrust.   4. The control circuit according to claim 3, wherein the control circuit simultaneously feeds, to each of at least some of the plurality of coils, a first applied current that outputs the first thrust and a second applied current that outputs the second thrust. 5. Actuator.   The actuator according to claim 4, wherein the first applied current and the second applied current have a phase shift of ¼ pitch with respect to a magnetic pole pitch of the multipolar magnet.   The control circuit corrects at least one of the first applied current and the second applied current based on a position of the mover so as to keep at least one of the first thrust and the second thrust constant. Item 6. The actuator according to Item 4 or 5.   The control circuit increases a current value of the second applied current applied when shifting from a state in which the stator and the mover are in contact to a separated state to be larger than the current value to be applied in a separated state. The actuator according to any one of claims 4 to 6.   The biasing mechanism includes a swing mechanism that swings relatively in a direction in which the multi-pole magnet and the plurality of coils face each other at a contact portion where the stator and the mover contact each other. The actuator according to any one of 1 to 7.   The actuator according to claim 1, further comprising a friction member at a contact portion where the stator and the mover contact each other.   The actuator according to any one of claims 1 to 9, wherein a ferromagnetic part is provided in a part of the contact part where the stator and the mover are in contact with each other and the multipolar magnet is in contact. A lens barrel comprising the actuator according to any one of claims 1 to 10,
The mover is a lens barrel that holds a lens. Having at least two movers relative to the stator;
The lens barrel according to claim 11, wherein the movable element holds a focus lens and a zoom lens.   An imaging device comprising the lens barrel according to claim 11.

Images