JP2014202908A - Optical member driving device and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To mitigate or avoid an impulsive force applied to an ultrasonic motor at the time of drop or collision, without adding a new component.SOLUTION: An optical member driving device drives an optical member 70 by an ultrasonic motor including a vibrating member 10 vibrating by an ultrasonic wave and a slide member 50 to which the vibrating member is pressed. A frictional force between the vibrating member and the slide member in a state where the vibrating member does not vibrate is larger in a front side range 52 and a rear side range 53 on the outside of a driving range 51 in which the optical member is driven by the ultrasonic motor, than in the driving range 51.

Description

  The present invention relates to an optical member driving apparatus and an imaging apparatus that drive an optical member such as a lens by an ultrasonic motor.

  Recently, a drive signal having a predetermined frequency is generated by a variable oscillator, and the drive signal is applied to a piezoelectric element via a power amplifier, thereby generating a traveling wave in a vibrating body joined to the piezoelectric element, A lens driving device using an ultrasonic motor that moves a moving body that makes contact with a predetermined pressure is known.

  A lens driving device using an electromagnetic linear actuator is also known (Patent Documents 1 and 2).

JP 2010-44166 A JP 2002-199690 A

  In the prior art disclosed in Patent Document 1 described above, the guide shaft 20 is connected to the lens barrel main body 10 in order to prevent a collision with the fixing member of the lens holding frame even when no power is supplied. A collision preventing member 40 for preventing a collision between the fixing member 25 and the lens unit 14 is provided.

  However, in order to prevent collision and prevent damage, a new part (collision preventing member 40) is added, resulting in a problem of cost increase and apparatus enlargement.

  In the technique disclosed in Patent Document 2, the guide 40 includes a cylindrical bush 42 fixed on the base and a lower end press-fitted into the bush in order to absorb collisions at both ends of the driving range. An upper damper 43 and a lower damper 44, which are elastic members for shock absorption, are disposed on the guide shaft 41 and the upper and lower ends of the guide shaft.

  However, since the dampers 43 and 44, which are new elastic absorbing members, are arranged at both ends of the ring-shaped bearing 324, there are problems that the cost is increased and the size of the apparatus is increased.

(Object of invention)
An object of the present invention is to provide an optical member driving device capable of reducing or avoiding an impact force applied to an ultrasonic motor when it is accidentally dropped or collides with an external object without adding new parts. And providing an imaging device.

  In order to achieve the above object, an optical member driving device according to the present invention includes a vibrating member that vibrates with ultrasonic waves and a sliding member that press-contacts the vibrating member, and the vibrating member and the sliding member are relative to each other. And an optical member driving device that drives the optical member by the ultrasonic motor, and the vibration member does not vibrate. The frictional force between the vibrating member and the sliding member in the state is greater in the front range and the rear range outside the drive range than the drive range in which the optical member is driven by the ultrasonic motor. Is characterized in that each is large.

  According to the present invention, it is possible to reduce or avoid the impact force applied to the ultrasonic motor when it is accidentally dropped or collides with an external object without adding new parts.

It is sectional drawing which shows the camera incorporating the lens drive device based on Example 1 of this invention. FIG. 3 is a diagram illustrating a vibrating body unit that forms part of the ultrasonic motor according to the first embodiment. 3 is a front view of an ultrasonic motor and a focus lens in Embodiment 1. FIG. FIG. 4 is a side view of FIG. 3. FIG. 4 is a top view of FIG. 3. It is AA sectional drawing of FIG. It is sectional drawing which shows the state after the drop impact of Example 1. FIG. It is a top view of the ultrasonic motor and focus lens in Example 2 of the present invention. It is a side view of FIG. It is sectional drawing of FIG. It is sectional drawing which shows the state after the drop impact of Example 2. FIG. It is a front view of the ultrasonic motor and focus lens in Example 3 of the present invention. It is AA sectional drawing of FIG. It is sectional drawing which shows the state after the drop impact of Example 3.

  The mode for carrying out the present invention is as described in Examples 1 to 3 below.

  A lens driving device as an optical member driving device that is Embodiment 1 of the present invention will be described below with reference to FIGS. This lens driving device is used in an imaging device such as a camera.

  Example 1 is a lens driving device using an ultrasonic motor. FIG. 1 is a cross-sectional view of a state in which a lens barrel incorporating the ultrasonic motor is attached to a camera body. In FIG. 1, a lens 70 is an optical system that moves in the optical axis direction during focusing, and the ultrasonic motor unit 1 drives the lens 70 in the optical axis direction. The lens barrel 2 is attached to the camera body 3. The ultrasonic motor unit 1 generates a moving force with respect to the rail 50 fixed to the lens barrel 2, and moves with the lens 70 while being guided by a main guide bar (described later) and a sub guide bar 100.

  First, referring to FIG. 2, the structure of the vibrating body unit used in the ultrasonic motor unit 1 will be described. The vibrating body 10 that is a component that is the core of the structure of the vibrating body unit is a rectangular thin plate shape of a magnetic material, and there are cylindrical projecting portions 11 and 12 at two centers. Holes 13 and 14 provided at both ends in the longitudinal direction of the vibrating body 10 are round holes for positioning and fixing to a support member 40 described later. Inside the holes 13 and 14, there are square holes 15 and 16, and the rigidity of the vibrating body 10 between the protrusion 11 and the hole 13 described above is weakened, and the rigidity between the protrusion 12 and the hole 14 is increased. It has a hole shape for weakening.

  A piezoelectric element 20 that has been subjected to a predetermined polarization treatment is attached to the opposite surface of the vibrating body 10 where the protrusions 11 and 12 do not exist, and the protrusions 11 and 12 viewed from the side are controlled by controlling the applied high-frequency voltage. Can be elliptically moved at different timings.

  The rectangular magnet 30 is a magnet whose longitudinal ends are magnetized to the S pole 31 and the N pole 32, and is bonded to the surface of the piezo element 20 with an adhesive that is elastic even after adhesive curing. When viewed from the side, the tip of the S pole 31 coincides with the center of the protrusion 11, and the tip of the N pole 32 coincides with the center of the protrusion 12.

  Next, the structure of the ultrasonic motor unit 1 and the focus lens driven by the ultrasonic motor unit 1 will be described with reference to FIGS.

  The support state of the lens 70 that is driven when the lens barrel 2 is focused will be described. As shown in FIG. 3 (front sectional view taken along the line BB of FIG. 4), FIG. 4 (side view of FIG. 3), and FIG. 5 (top view of FIG. 3), the lens 70 includes a lens holder 80. It is held by being glued and fixed in the center of. In the main guide bar 90 fixed in the lens barrel 2, a bar fitting hole 84 in the rib portion 82 above the lens holder 80 and a bar fitting hole 85 in the rib portion 83 ( (Not shown) is slidably fitted in the axial direction of the main guide bar 90. Further, the sub guide bar 100 fixed in the lens barrel 2 has a slight gap so that the bar fitting groove 86 below the lens holder 80 is slidable in the axial direction of the sub guide bar 100. Are mated. Thereby, the vibrating body 10 and the rail 50 move relatively. The main guide bar 90 and the sub guide bar 100 are supported by bar support members 160 and 161 as shown in FIG.

  The support member 40, which is a core component of the ultrasonic motor unit 1, is provided with the convex portions 45 and 46 shown in FIG. 6, and is fitted into the holes 13 and 14 of the vibrator unit described with reference to FIG. Have been glued and fixed. The fitting portion 44 of the support member 40 is rotatably fitted to the support shaft 60 supported by the rib portions 82 and 83 above the lens holder 80. The fitting portion 44 is connected to the element support portions 41 and 42 by the connecting portion 43.

  The rail 50 fixed in the lens barrel 2 is made of a magnetic material having a rectangular shape when viewed from the front. The tips of the projections 11 and 12 of the vibrating body 10 are in pressure contact with the sliding surface of the upper surface, and the slide is made. It is in a positional relationship that moves.

  The state of the lines of magnetic force will be described with reference to FIG. 6 (AA cross-sectional view in FIG. 3).

  Most of the magnetic lines of force pass through the piezo element 20 from the tip of the N pole 32 of the magnet 30, and pass through the rail 50 in contact with the tip of the protrusion 12 of the vibrating body 10. Then, from the tip of the projection 11 in contact with the rail 50, it passes through the vibrating body 10, passes through the piezo element 20, and returns to the tip of the S pole 31 of the magnet 30. As a result, the protrusions 11 and 12 of the vibrating body 10 are attracted to the sliding surface of the rail 50 by a magnetic force.

  Next, the movement of the lens 70 to advance and retract in the optical axis direction by the ultrasonic motor will be described.

  By controlling the high-frequency voltage applied to the piezo element 20 that has been subjected to a predetermined polarization treatment, the tips of the protrusions 11 and 12 are formed as shown in FIG. Each ellipse motion is performed in different phases. As shown in FIG. 6, the tips of the protrusions 11 and 12 are attracted by the magnetic force between the surfaces of the rails 50, so The force of kicking while doing elliptical motion on the sliding surface works. The kicking force causes the lens 70 to move out. Further, the lens 70 can be retracted by controlling the voltage waveform applied to the piezo element 20 so that the rotation of the elliptical motion is reversed. This detailed mechanism is the same as the mechanism described in the published Japanese Patent Application Laid-Open No. 2001-292584.

  In FIG. 6, the focus drive range 51 of the surface of the rail 50 with which the protrusions 11 and 12 of the vibrating body 10 are in contact is moved by the protrusions 11 and 12 of the vibrating body 10 during the operation of focusing on the subject. The surface state is such that the driving speed and the driving force are easily generated with a very smooth surface roughness.

  The front range 52 outside the focus drive range 51 is a range in which the protrusions 11 and 12 of the vibrating body 10 do not contact even when the lens 70 is extended to the left in FIG. 6 so that the close range is in focus. There is a range in which the protrusions 11 and 12 of the vibrating body 10 do not enter during normal photographing. The surface roughness here is rougher than the focus use range 51, and the friction coefficient μ is high.

  The rear range 53 outside the focus drive range 51 is not in contact with the protrusions 11 and 12 of the vibrating body 10 even when the lens 70 is retracted in the right direction in FIG. This is a range in which the protrusions 11 and 12 of the vibrating body 10 do not enter during normal photographing. The surface roughness here is rougher than the focus use range 51, and the friction coefficient μ is high.

  Next, the action when the vehicle is accidentally dropped and receives a drop impact will be described.

  It is assumed that the lens barrel 2 is attached to the camera body 3 and the user accidentally drops it on the ground with the camera power switch turned off. At the moment when the tip of the lens barrel 2 collides with the ground, the focusing lens 70 generates a force F1 that tends to move to the left in FIG. 6 due to its own inertial force.

  In FIG. 6, the friction force F <b> 2 that tries to stay at this position on the protrusion 11 of the vibrating body 10 pressed against the surface of the rail 50 against the force F <b> 1 acting on the lens 70, and the friction on the protrusion 12. Although the force F3 is generated, since F1> F2 + F3, the lens 70 starts to shift to the left in FIG.

  Then, at the moment of the position shown in FIG. 7, the lens 70 is displaced, and the protrusion 11 of the vibrating body 10 enters the front range 52 of the rail having a high friction coefficient. Therefore, the frictional force F2 of the protrusion 11 of the vibrating body 10 becomes larger than that in the state of FIG. 6, and F1 <F2 + F3, that is, the resultant force F2 + F3 of the resistance force tries to move to the left side of FIG. It becomes larger than force F1 and stops at this place.

  Therefore, it is possible to avoid the element support portion 41 from colliding with the bar support member 160.

  As described above, it is possible to avoid an impact applied to the ultrasonic motor unit when the lens barrel is accidentally dropped or collided with an external object.

  A second embodiment of the present invention will be described with reference to FIGS.

  The structure of the ultrasonic motor unit will be described with reference to FIG. Since the structures of the vibrating body 10 and the piezoelectric element 20 are the same as those in the first embodiment, description thereof is omitted here.

  The mechanism different from the first embodiment is that the structure for pressing the protrusions 11 and 12 of the vibrating body 10 against the surface of the rail 250 is not a magnetic force but a pressure spring 210. The pressure spring 250 forms an elastic member.

  In FIG. 8, a winding portion 212 wound twice in the middle of the pressurizing spring 10 that is a torsion coil spring is fitted into the support shaft 60 protruding from the rib portion 82. The fixing portion 213 that is one end of the pressure spring is fitted into the spring fixing hole 88 of the rib portion 82. A tip end 211 that is the other end of the pressure spring 210 presses the surface of the support member 40. In FIG. 10, since the tip 211 presses the support member 40 downward in FIG. 10, the protrusions 11 and 12 of the vibrating body 10 connected to the support member 40 press against the surface of the rail 250. Has been.

  In the focus drive range 251 at the center of the rail 250 in FIG. 10, the surface of the rail 250 is flat and is horizontal with the optical axis, but the surface of the left front range 252 is an inclined surface, It is going up. Further, the surface of the rear region 253 on the right side is also an inclined surface and rises upward in FIG. That is, the position of the sliding surface of the rail 250 is closer to the vibrating body 10 in the front range 252 and the rear range 253 than in the focus drive range 251.

  Next, the action when the vehicle is accidentally dropped and collides with the ground will be described.

  This lens barrel 2 is attached to the camera body 3 of FIG. 1, and it is assumed that the user accidentally dropped it on the ground with the power switch of the camera turned off. At the moment when the tip of the lens barrel 2 collides with the ground, the focusing lens 70 generates a force F1 that tends to move to the left in FIG. 1 due to its own inertial force.

  In FIG. 10, against the force F <b> 1 acting on the lens 70, the frictional force F <b> 2 trying to stay at this position on the protrusion 11 of the vibrating body 10 pressed on the surface of the rail 250, and the protrusion 12 Although the frictional force F3 is generated, since F1> F2 + F3, the lens 70 starts to shift to the left in FIG.

  When the lens 70 is displaced and moved to the position of FIG. 11, the protrusion 11 of the vibrating body 10 reaches the slope of the front range 252, and the support member 40 to which the vibrating body 10 is connected is upward. The tip portion 211 of the pressure spring 210 that presses the support member 40 is also lifted upward. Due to the deformation of the tip 211 of the pressure spring 210, the pressing force is increased, and the frictional force F2 of the protrusion 11 and the frictional force F3 of the protrusion 12 are increased, and F1 <F2 + F3, that is, the resultant force F2 + F3 of the resistance force. Becomes larger than the force F1 trying to move to the left side of FIG. 11, and stops at this point.

  Therefore, it can avoid that the element support part 41 collides with the bar support member 160 (FIG. 6).

  As described above, when the lens barrel is accidentally dropped or collided with an external object, the impact applied to the ultrasonic motor unit can be avoided and alleviated.

  A third embodiment of the present invention will be described with reference to FIGS.

  The structure of the ultrasonic motor unit will be described with reference to FIG. Since the structures of the vibrating body 10 and the piezoelectric element 20 are the same as those in the first embodiment, description thereof is omitted here.

  The mechanism different from the first embodiment is that the structure for pressing the protrusions 11 and 12 of the vibrating body 10 against the sliding surface of the rail 50 is not a magnetic force but a pressure spring 340. The pressure spring 340 constitutes an elastic member.

  In FIG. 12, a pressure spring 340 that is a compression coil spring is sandwiched between the upper surface of the support member 40 and the upper portion 313 of the spring support member 310. The spring support member 310 extends downward, and a roller shaft 311 and a roller shaft 312 are fixed thereto. A roller 330 is rotatably fixed to the roller shaft 312. A roller 320 is rotatably fixed to the roller shaft 311. The rollers 330 and 320 are in contact with the lower surface of the rail 50. In FIG. 13, the guide shaft 314 of the spring support member 310 is fitted into the guide hole 47 of the support member 40 so as to be movable up and down. Further, the guide shaft 315 of the spring support member 310 is fitted into the guide hole 48 of the support member 40 so as to be movable up and down. Accordingly, the upper portion 313 of the spring support member 310 that supports one end of the pressure spring 340 can be displaced. With this structure, the distance between the support member 40 and the upper portion 313 of the spring support member 310 is changed to follow the expansion and contraction of the pressure spring 340, and the force of the pressure spring 340 can be transmitted to the rollers 320 and 330. .

  Then, the protrusion 11 and the protrusion 12 of the vibrating body 10 are pressed against the surface of the rail 50 by the pressing force of the compressed pressure spring 340. Further, the rollers 320 and 330 are pressed against the lower surface of the rail 50 by the spring force of the pressure spring 340.

  In FIG. 12, the inner wall member 350 is a structural member fixed inside the lens barrel 2 and is located above the spring support member 310. In FIG. 13 (AA sectional view of FIG. 12), in the focus drive range 351 at the center of the lower surface of the inner wall member 350, the surface is flat and horizontal to the optical axis, but the surface of the left front range 352 is It becomes a slope and goes down in FIG. Further, the surface of the rear region 353 on the right side is also an inclined surface and is lowered downward in FIG.

  Next, the action when the vehicle is accidentally dropped and collides with the ground will be described.

  This lens barrel 2 is attached to the camera body 3 of FIG. 1, and it is assumed that the user accidentally dropped it on the ground with the power switch of the camera turned off. At the moment when the tip of the lens barrel 2 collides with the ground, the focusing lens 70 generates a force F1 that tends to move to the left in FIG. 1 due to its own inertial force.

  In FIG. 13, against the force F <b> 1 acting on the lens 70, the frictional force F <b> 2 that tries to stay at this position on the protrusion 11 of the vibrating body 10 pressed on the surface of the rail 50, and the protrusion 12 Although the frictional force F3 is generated, since F1> F2 + F3, the lens 70 starts to shift to the left in FIG.

  When the lens 70 is displaced and moved to the position of FIG. 14, the left corner of the upper portion 313 of the spring support member 310 abuts on the slope of the front range 352 of the inner wall member 350, and the spring support member 310 Is displaced along and pushed down. For this reason, the pressure spring 340 is compressed. Due to the increased compression spring force (elastic force), the frictional force F2 of the protrusion 11 and the frictional force F3 of the protrusion 12 increase, and F1 <F2 + F3, that is, the resultant force F2 + F3 of the resistance force is as shown in FIG. It becomes larger than the force F1 trying to move to the left and stops at this place.

  Therefore, it can avoid that the element support part 41 collides with the bar support member 160 (FIG. 6).

  As described above, when the lens barrel is accidentally dropped or collided with an external object, the impact applied to the ultrasonic motor unit can be avoided and alleviated.

  In the first to third embodiments, an example is shown in which the present invention is applied to an ultrasonic linear motor. However, the present invention can also be applied to an ultrasonic rotary motor. In that case, the vibrating body (vibrating member), the rail (sliding member) and the like are annular. Further, the total angle of the focus drive range 51, the front range 52, and the rear range 53 is limited to a case of 360 ° or less.

  The ultrasonic motor is not limited to the wedge type, and may be a traveling wave type.

DESCRIPTION OF SYMBOLS 1 Ultrasonic motor unit 10 Vibrating body 20 Piezo element 50, 250 Rail 51, 251, 351 Focus drive range 52, 252, 352 Front side range 53, 253, 353 Rear side range 70 Lens 210, 340 Pressure spring 350 Inner wall member

Claims (7)

An ultrasonic motor that includes a vibration member that vibrates with ultrasonic waves and a sliding member to which the vibration member is pressed, and the vibration member and the sliding member relatively move;
An optical member held movably in the optical axis direction,
An optical member driving device for driving the optical member by the ultrasonic motor,
The frictional force between the vibrating member and the sliding member in a state where the vibrating member does not vibrate is a front range outside the driving range than the driving range in which the optical member is driven by the ultrasonic motor. An optical member driving device characterized in that the rear range is larger.   2. The optical member driving device according to claim 1, wherein a friction coefficient of the sliding member is larger in each of the front side range and the rear side range than the driving range.   2. The vibration member is pressed against the sliding member by an elastic member, and the pressing force by the elastic member is larger in the front range and the rear range than in the driving range, respectively. An optical member driving apparatus according to claim 1.   4. The optical member drive according to claim 3, wherein the sliding surface of the sliding member is closer to the vibration member in the front range and the rear range than in the drive range. apparatus. A displaceable support member for supporting one end of the elastic member;
A structural member that contacts the support member in the front range and the rear range,
The optical device according to claim 3, wherein the support member is displaced in a direction in which an elastic force of the elastic member is increased when the support member is in contact with the structural member in the front range and the rear range. Member drive device.   The optical member driving apparatus according to claim 1, wherein the sliding member is a fixed rail.   The imaging apparatus according to claim 1, further comprising the optical member driving device.

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