JP2017169427A - Linear drive device, lens barrel, and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear drive device excellent in responsiveness.SOLUTION: A lens drive device 300 for driving a lens holding member 13 in an X direction by a first actuator 100A and a second actuator 100B is structured so that a first connection member 15 driven by the first actuator 100A is energized to the lens holding member 13 in a +X direction by a first energizing member 16 and a second connection member 25 driven by the second actuator 100B is energized to the lens holding member 13 in a -X direction by a second energizing member 26. For instance, when the lens holding member 13 is driven in the +X direction, both of the first connection member 15 and the second connection member 25 are driven in the +X direction by the first actuator 100A and the second actuator 100B. At this time, the drive force of the first actuator 100A is made larger than the drive force of the second actuator 100B.SELECTED DRAWING: Figure 2

Description

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

  Shooting scenes with imaging devices such as digital single-lens reflex cameras include shooting scenes in which the direction of movement of the subject changes frequently and shooting scenes in which the imaging device itself moves greatly. In such shooting scenes, the autofocus function for the subject High responsiveness is required. In response to such a demand, for example, by using a vibration type actuator for the driving mechanism of the autofocus lens, it is possible to obtain quietness, high speed driving performance, high followability in autofocusing on a subject moving at high speed, and the like. . As a vibration-type actuator used for lens driving, high-frequency vibration is generated in a vibration body formed by joining a plate-like elastic body and a piezoelectric element, and a friction member in pressure contact with the vibration body is frictionally driven to vibrate. What moves a body and a friction member relatively is known.

  FIG. 11A is a perspective view showing a schematic configuration of an example of a conventional lens driving device using a vibration type actuator, and FIG. 11B is a plan view showing an enlarged part of the lens driving device. It is. In this lens driving device, a lens holding member 913 which is a driven member holds a lens 912 and is connected to a movable member 905 of a vibration type actuator via a connecting member 915, and slides with two guide members 911. It is movably fitted. The movable member 905 is configured to be movable in the X direction, and has a structure in which the lens holding member 913 is guided by the guide member 911 and moves in the X direction as the movable member 905 moves. Here, the connecting member 915 is urged in the arrow C direction with respect to the lens holding member 913 by the urging member 916 (see Patent Document 1).

Japanese Patent Laying-Open No. 2015-133864

  However, the lens driving device shown in FIG. 11 has high responsiveness when driving the lens holding member 913 in the + X direction, which is the same as the arrow C direction, but is responsive when driving in the opposite -X direction. There is a problem that it falls. That is, at the time of acceleration / deceleration in which the movable member 905 is driven in the + X direction in order to drive the lens holding member 913 in the + X direction, the connecting member 915 applies a thrust to the lens holding member 913 in the + X direction. Since the direction of this thrust and the direction of arrow C in which the connecting member 915 is urged by the urging member 916 are the same direction, the lens holding member 913 moves following the movable member 905 to obtain high responsiveness. It is done. On the other hand, at the time of acceleration / deceleration in which the movable member 905 is driven in the −X direction in order to drive the lens holding member 913 in the −X direction, the connecting member 915 is in the direction of the arrow H with respect to the lens holding member 913 via the biasing member 916. To give thrust. Since the thrust in the direction of arrow H and the biasing force in the direction of arrow C are opposite directions, if the thrust in the direction of arrow H is greater than the biasing force in the direction of arrow C, the biasing member 916 is compressed and the lens holding member 913 cannot move following the movable member 905. That is, in the lens driving device shown in FIG. 11, the responsiveness may decrease when the lens holding member 913 is driven in the −X direction.

  If the movable member 905 and the lens holding member 913 are fixedly joined by the connecting member 915 without using the biasing member 916, the lens holding member 913 can be driven in any of the + X direction and the −X direction. It is considered that high responsiveness can be obtained. However, if the movable member 905, the connecting member 915, and the lens holding member 913 have a structure that does not give freedom of movement between the components, extremely high dimensional accuracy is required for each component, and components can be mounted with extremely high accuracy. It is necessary to assemble. If this requirement is not satisfied, the lens holding member 913 cannot be driven smoothly in the X direction, which is not a realistic countermeasure.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a linear drive device with improved responsiveness regardless of the drive direction of a driven member.

  The linear drive device according to the present invention connects a driven member, a first drive source, the first drive source, and the driven member, and drives the drive force of the first drive source to the driven A first connecting member that transmits to the member, a second driving source, the second driving source, and the driven member are connected, and the driving force of the second driving source is transmitted to the driven member. And a first connecting member that urges the first connecting member in a first direction relative to the driven member to bring the first connecting member and the driven member into pressure contact with each other. The urging means and the second connecting member are urged against the driven member in a direction opposite to the first direction to bring the second connecting member and the driven member into pressure contact. And a second urging means.

  According to the present invention, a linear drive device with excellent responsiveness can be realized.

It is a disassembled perspective view which shows schematic structure of the vibration type actuator which comprises the lens drive device which concerns on embodiment of this invention. It is a top view which shows schematic structure of the lens drive device which concerns on 1st Embodiment provided with the vibration type actuator of FIG. 1, a front view, the partially expanded view of a top view, and arrow BB sectional drawing. It is a block diagram which shows schematic structure of the imaging device which has the lens drive device of FIG. 4 is a flowchart illustrating autofocus control of the imaging apparatus in FIG. 3. It is a figure which shows the frequency characteristic of the 1st actuator which comprises the lens drive device of FIG. 2, and a 2nd actuator. It is a figure explaining the frequency correction method for adjusting the drive force of the 1st actuator which comprises the lens drive device of FIG. 2, and a 2nd actuator. It is a figure which shows the frequency characteristic of the 1st actuator which comprises the lens drive device of FIG. 2, and a 2nd actuator. It is the front view and partial enlarged view which show schematic structure of the lens drive device which concerns on 2nd Embodiment. It is a front view explaining the urging force which acts on a lens holding member by the 1st urging member and the 2nd urging member in the lens drive device concerning a 1st embodiment. It is a front view explaining the biasing force which acts on a lens holding member by the 1st biasing member and the 2nd biasing member in the lens drive device which concerns on 3rd Embodiment. FIG. 6 is a perspective view showing a schematic configuration of a conventional lens driving device using a vibration type actuator, and a plan view showing an enlarged part of the lens driving device.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Here, as an example of the linear drive device according to the present invention, a lens drive device that drives a lens provided in a lens barrel of the imaging device in the optical axis direction is taken up.

  FIG. 1A is an exploded perspective view showing a schematic configuration of a vibration type actuator 100 constituting the lens driving device according to the embodiment of the present invention. For convenience of explanation, an X direction (X axis), a Y direction (Y axis), and a Z direction (Z axis) orthogonal to each other are determined as shown in FIG. The X direction (first direction) is a relative moving direction between a friction member 1 and a vibrating body 2 described later. The Z direction (second direction) is a pressurizing direction in which the vibrating member 2 is pressed against the friction member 1 in order to press the friction member 1 and the vibrating member 2 in pressure contact. The direction from the friction member 1 to the vibrating body 2 is defined as the -Z direction. The Y direction is a direction orthogonal to the X direction and the Z direction. FIG. 1B is a ZX sectional view of the vibration type actuator 100. FIG. 1C is a perspective view of the vibrating body 2 constituting the vibration type actuator 100.

  The vibration type actuator 100 includes a friction member 1, a vibrating body 2, a holding member 3, a pressure member 4, a movable member 5, a fixed member 6, a rolling member 7, a top plate 8, a buffer member 9, a pressure plate 10, and a roller 11. Is provided. The friction member 1 is a member having a sliding surface 1 a that is in pressure contact with the vibrating body 2 and receives a frictional driving force from the vibrating body 2, and is fixed to the fixed member 6.

  The vibrating body 2 includes an elastic body 2a and a piezoelectric element 2b. The elastic body 2a has a thin plate-like rectangular shape, and an arm portion 2a2 connected to the holding member 3 is provided at an end in the X direction which is a longitudinal end. A rectangular plate-like piezoelectric element 2b is bonded to one surface of the elastic body 2a with an adhesive or the like. Two protrusions 2a1 are provided at a predetermined interval in the X direction on the surface of the elastic body 2a opposite to the surface to which the piezoelectric element 2b is bonded. Here, as shown in FIG. 1 (b), the protrusion 2a1 is formed integrally (continuously) with the elastic body 2a by pressing the elastic body 2a or the like. Note that the protrusion 2a1 may be joined to the elastic body 2a by welding or the like. The tip surface of the protrusion 2a1 is in pressure contact with the sliding surface 1a of the friction member 1. The arm 2 a 2 of the vibrating body 2 is fixed to the holding member 3, whereby the vibrating body 2 is held by the holding member 3.

  The piezoelectric element 2b, which is an electro-mechanical energy conversion element, is provided with two-phase electrodes (not shown). An AC voltage is applied to each electrode of the piezoelectric element 2b through a flexible substrate (not shown) so that the vibration body 2 is excited with a predetermined phase difference between two natural vibration modes. As a result, elliptical motion in the ZX plane occurs in the protrusion 2a1, and the protrusion 2a1 frictionally drives the friction member 1. At this time, by providing the arm portion 2a2 at a position that becomes a node of the natural vibration mode, it is avoided that the vibration generated in the vibrating body 2 is suppressed by the holding member 3, and conversely, the vibration generated in the vibrating body 2 is held. Transmission to the member 3 can be suppressed. In this embodiment, as will be described later, the vibrating body 2 moves relative to the fixed friction member 1 in the X direction by a reaction force when the protrusion 2a1 frictionally drives the friction member 1. . Further, the two natural vibration modes excited by the vibrating body 2 are not particularly limited, and examples thereof include a primary out-of-plane bending vibration mode and a secondary out-of-plane bending vibration mode. Since vibration excitation methods in these natural vibration modes are well known, description thereof is omitted here.

  The movable member 5 is engaged with the holding member 3 via the roller 11. For this reason, the holding member 3 is restricted from moving in the X direction with respect to the movable member 5, but is not restricted in the Z direction. The movable member 5 has a spherical protrusion-shaped power transmission portion 5a. The power transmission unit 5a is connected to a lens holding member described later. The pressurizing member 4 is a member that presses the vibrating body 2 against the friction member 1, and one end in the Z direction is an action surface 5 b of the movable member 5, and the other end in the Z direction is an action surface 10 a of the pressurizing plate 10. In contact. The pressurizing member 4 applies pressure to the vibrating body 2 via the pressurizing plate 10 and the buffer member 9 to bring the vibrating body 2 into pressure contact with the friction member 1. At this time, the vibration member 2 is pressurized against the friction member 1 without interfering with the vibration generated in the vibration member 2 by interposing the buffer member 9 between the pressure member 4 and the vibration member 2. Can do.

  The top plate 8 is fixed to the fixing member 6 using screws or the like. A rolling member 7 is disposed between the movable member 5 and the top plate 8. The rolling member 7 is sandwiched between a guide groove 5 c provided in the movable member 5 and a guide groove 8 a provided in the top plate 8 so as to extend in the X direction. When the rolling member rolls while being guided by the guide grooves 5c and 8a, the movable member 5 is reduced while reducing the sliding load generated between the movable member 5 and the top plate 8 by the pressure applied by the pressure member 4. And the fixing member 6 can be relatively moved in the X direction. The holding member 3 to which the vibrating body 2 is connected is restricted from moving in the X direction with respect to the movable member 5, and the friction member 1 is fixed to the fixed member 6. Therefore, when the vibration in the natural vibration mode is excited in the vibrating body 2, the vibrating body 2, the holding member 3, and the movable member 5 are integrally moved relative to the fixed member 6 in the X direction. Therefore, the lens holding member can be driven in the X direction by connecting the lens holding member to the power transmission portion 5 a provided in the movable member 5.

  Next, the lens driving device according to the first embodiment including the vibration type actuator 100 will be described. FIG. 2A is a plan view illustrating a schematic configuration of the lens driving device 300 according to the first embodiment. FIG. 2B is a front view illustrating a schematic configuration of the lens driving device 300. FIG. 2C is a partially enlarged view of the plan view of FIG. FIG.2 (d) is a partially expanded view of sectional drawing by arrow BB shown to Fig.2 (a).

  The lens driving device 300 includes a first vibration type actuator 100A (hereinafter referred to as “first actuator 100A”) as a first drive source and a second vibration type actuator 100B (hereinafter referred to as “first actuator 100A”) as a second drive source. 2nd actuator 100B "). The lens driving device 300 includes the lens 12, the lens holding member 13, the guide members 14a and 14b, the first connecting member 15, the first biasing member 16, the fixed shaft 17, the second connecting member 25, and the second. The urging member 26 is provided.

  The configurations of the first actuator 100A and the second actuator 100B are the same as those of the vibration actuator 100 described above. Therefore, in the following description, when describing as a component of the vibration type actuator 100 and the component of the first actuator 100A, “first” is added before the name of the component and “ A "shall be attached. Similarly, when describing as a component of the second actuator 100B, “second” is added before the name of the component, and “B” is added at the end of the reference numeral. For example, when the “movable member 5” of the vibration type actuator 100 is described as a component of the first actuator 100A, it is referred to as “first movable member 5A” and is described as a component of the second actuator 100B. Is referred to as “second movable member 5B”. The description of the configuration of each of the first actuator 100A and the second actuator 100B is the same as the above description of the vibration type actuator 100, and is therefore omitted.

  A lens holding member 13 that is a driven member holds the lens 12. The lens holding member 13 has a round hole portion 13a and a U-shaped hole portion 13b. The lens holding member 13 is slidably fitted to the guide member 14a in the round hole portion 13a, and slides on the guide member 14b in the U-shaped hole portion 13b. It is movably fitted. Thus, the lens holding member 13 is guided in the X direction by the guide members 14a and 14b so as to be able to go straight. Note that the U-shaped hole 13b of the lens holding member 13 has a fitting play with respect to the guide member 14b. In the lens driving device 300, the driving force of the first actuator 100 </ b> A and the second actuator 100 </ b> B is transmitted to the lens holding member 13, so that the lens 12 held by the lens holding member 13 moves straight in the X direction.

The first actuator 100A and the second actuator 100B are arranged so as to be point-symmetric with respect to the point O when viewed from the Z direction. First, the first actuator 100A and its surroundings in the lens driving device 300 are firstly provided. The relationship with the configuration will be described. The first connecting member 15 connects the lens holding member 13 and the first actuator 100A. The first connecting member 15 is arranged to be rotatable around the fixed shaft 17 with respect to the lens holding member 13. The first urging member 16 is compressed in the X direction by contacting the surface 13c of the lens holding member 13 and the surface 15a of the first connecting member 15 in a state where the fixed shaft 17 is inserted. Accordingly, the first connecting member 15 is urged in the direction of the arrow C with respect to the lens holding member 13 and is in pressure contact with the lens holding member 13. A toggle spring is used for the first biasing member 16, and each end of the toggle spring acts on the receiving portion 13 e 1 of the lens holding member 13 and the convex portion 15 b of the first connecting member 15. . Thereby, an urging force for rotating the first connecting member 15 around the fixed shaft 17 is generated with respect to the lens holding member 13, and the first movable member 5 </ b> A from the V-shaped groove portion 15 c provided in the first connecting member 15. The urging force F _A acts in the −Z direction on the first power transmission unit 5aA. Thus, when the V-shaped groove portion 15c engages with the first power transmission portion 5aA, the first connecting member 15 is connected to the first movable member 5A of the first actuator 100A. As a result, the first movable member 5 </ b> A is coupled to the lens holding member 13 via the first coupling member 15.

Thus, by connecting the lens holding member 13 and the first movable member 5 </ b> A using the first biasing member 16, component tolerances, assembly tolerances, and the like can be absorbed. The direction of the biasing force F _A that acts on the first connecting member 15 and the direction of the urging force G by the first biasing member 16 which act by the first pressure member 4A to the first movable member 5A is Both are in the −Z direction. Therefore, the first connecting member 15 can be connected to the first movable member 5A without canceling the pressure applied by the first pressure member 4A.

The second actuator 100B is coupled to the lens holding member 13 in the same manner as the first actuator 100A. That is, the second connecting member 25 is attached to the lens holding member 13 so as to be rotatable around the fixed shaft 17. The second urging member 26 comes into contact with the receiving surface 13d of the lens holding member 13 and the surface 25a of the second connecting member 25 in a state where the fixed shaft 17 is inserted, and is compressed in the X direction. Accordingly, the second connecting member 25 is urged in the direction of the arrow D with respect to the lens holding member 13 and is in pressure contact with the lens holding member 13. Each end of the toggle spring used for the second urging member 26 acts on the receiving portion 13e2 of the lens holding member 13 and the convex portion (not shown) of the second connecting member 25. Thus, the first power transmission unit force F _B with the -Z direction with respect to the (not shown) from the second V-shaped groove provided in the connecting member 25 (not shown) the second movable member 5B Works. Thus, the second connecting member 25 is connected to the second movable member 5B of the second actuator 100B. As a result, the second movable member 5 </ b> B is coupled to the lens holding member 13 via the second coupling member 25. In the lens driving device 300, the magnitudes of the urging forces F _A and F _B are substantially equal, and the directions thereof are also substantially parallel.

  FIG. 3 is a block diagram illustrating a schematic configuration of the imaging device 400 having the lens driving device 300. The imaging device 400 includes a lens barrel 20 that houses a lens driving device 300, a main body 22 that houses an imaging device 21, a lens position detection unit 18a, an acceleration detection unit 18b, a focus position detection unit 18c, and a drive control unit 19. . In FIG. 3, for convenience of explanation, these main parts constituting the imaging device 400 are shown extracted from the imaging device 400, and the first actuator 100A and the second actuator 100B constituting the lens driving device 300 are similarly lens mirrors. It is shown extracted from the cylinder 20.

  The light beam that has passed through the lens barrel 20 forms an image on the image sensor 21, and the image sensor 21 converts the optical image into an electrical signal, and an image processing circuit (not shown) generates image data from the electrical signal. The lens position detection unit 18a includes a sensor provided in the lens barrel 20 and an arithmetic circuit provided in the main body unit 22 for processing a signal from the sensor, and determines the position of the lens 12 (lens holding member 13). To detect. The acceleration detection unit 18b includes a sensor provided in the lens barrel 20 and an arithmetic circuit provided in the main body unit 22 for processing a signal from the sensor, and when the lens 12 is driven in the optical axis direction. The acceleration of is detected. The focus position detection unit 18 c is provided in the main body unit 22, detects the focus position of the lens 12 using a known method such as a phase difference detection method, and supplies the focus position information to the drive control unit 19. . The drive control unit 19 determines the drive target position of the lens 12 based on the focus position information supplied from the focus position detection unit 18c. Then, the drive control unit 19 controls the driving of the first actuator 100A and the second actuator 100B based on the lens position detection unit 18a, the acceleration detection unit 18b, and information, and moves the lens 12 to the in-focus position.

  The drive control unit 19 includes a CPU (arithmetic processing circuit), a ROM, a RAM, and the like. When the CPU expands the computer program stored in the ROM to the RAM, the operation of each unit constituting the imaging apparatus 400 is controlled, whereby the overall control of the imaging apparatus 400 is realized. The drive control unit 19 may be a dedicated processor such as an ASIC that implements all or part of the processing of each unit constituting the imaging apparatus 400 by a logic circuit. The same applies to the lens position detection unit 18a, the acceleration detection unit 18b, and the focus position detection unit 18c, which can be implemented by software (program) or hardware, and is implemented by a combination of software and hardware. It may be.

  FIG. 4 is a flowchart for describing autofocus control of the imaging apparatus 400. Each process shown in the flowchart of FIG. 4 is realized by the drive control unit 19 executing a predetermined program to control the operation of each unit constituting the imaging apparatus 400. In the following description, the arrow C direction shown in FIG. 2C is defined as the + X direction, and the arrow D direction is defined as the −X direction. Further, it is assumed that the direction from the image sensor 21 toward the subject (not shown) is the + X direction, and the value (coordinate value) that defines the lens position increases as the optical axis direction advances in the + X direction.

Drive control unit 19, a driving target position X _t of the lens 12 is determined based on the obtained focus position information from the focus position detection unit 18c in step S11, the current lens position X from the lens position detector 18a in step S12 _{Get 0} . Drive control unit 19 in step S13, based on the drive target position _{X t} and the lens position _{X 0,} the driving direction of the lens 12 determines whether the + X direction or -X direction. If “Xt> X ₀ ”, it is necessary to drive the lens 12 in the + X direction. If “Xt ≦ X ₀ ”, it is necessary to drive the lens 12 in the −X direction. Will be. Therefore, when “Xt> X ₀ ” (YES in S13), the drive control unit 19 advances the process to step S14, and when “Xt ≦ X ₀ ” (NO in S13), the process proceeds to step S20. Proceed.

  In step S14, the drive control unit 19 supplies a predetermined AC voltage to the first actuator 100A and the second actuator 100B so that both the first movable member 5A and the second movable member 5B are driven in the + X direction. . Thereby, the driving of the lens driving device 300 is started. In step S15, the drive control unit 19 determines whether the lens 12 is accelerating or decelerating or moving at a constant speed based on the signal from the acceleration detecting unit 18b. If the lens 12 is accelerating or decelerating (YES in S14), the drive control unit 19 advances the process to step S16. If the lens 12 is moving at a constant speed (NO in S14), the driving control unit 19 performs the process. Proceed to S17.

In step S16, the drive control unit 19 controls the driving of the lens driving device 300 so that the driving force of the first actuator 100A is larger than the driving force of the second actuator 100B. Accordingly, a thrust is applied in the + X direction to the lens holding member 13 via the first connecting member 15 by the first movable member 5A of the first actuator 100A. At this time, the direction in which the first urging member 16 urges the first connecting member 15 against the lens holding member 13 is also the + X direction. Therefore, since the lens holding member 13 can be driven following the movement of the first movable member 5A, high responsiveness can be obtained. In step S17, the drive control unit 19 controls the driving of the lens driving device 300 so that the driving force of the first actuator 100A and the driving force of the second actuator 100B are equal, thereby moving the lens 12 at a constant speed. be able to. Step S16, S17 the drive control unit 19 in step S18 subsequent to the lens 12 (lens position _{X 0)} determines whether the host vehicle has reached the drive target position _{X t.} Drive control unit 19, when the lens 12 has reached the drive target position _{X t} (YES in S18), to terminate the present process, when the lens 12 has not reached the drive target position _{X t} (NO in S18), The process returns to step S15.

  The processes in steps S20, S21, S22, S23, S24, and S25 correspond to the processes in steps S14, S15, S16, S17, S18, and S19, respectively. These processes are different in that the direction in which the lens 12 is moved is the −X direction, which is the opposite direction to the + X direction, and the processes in steps S20 to S25 are the same as the processes in steps S14 to S19. Since this is done, the description is omitted. In step S22 corresponding to step S16, the drive control unit 19 controls the driving of the lens driving device 300 so that the driving force of the second actuator 100B is larger than the driving force of the first actuator 100A. Accordingly, a thrust is applied in the −X direction to the lens holding member 13 via the second connecting member 25 by the second movable member 5B of the second actuator 100B. At this time, the direction in which the second urging member 26 urges the second connecting member 25 against the lens holding member 13 is also the −X direction. Therefore, since the lens holding member 13 can be moved following the second movable member 5B, high responsiveness can be obtained.

  As described above, in the drive control in the imaging apparatus 400, the first actuator 100A is controlled according to the relationship between the urging directions of the first urging member 16 and the second urging member 26 and the driving direction of the lens 12. The magnitude of the driving force and the driving force of the second actuator 100B is switched. Thereby, high responsiveness can be obtained regardless of which of the + X direction and the −X direction the driving direction of the lens 12 is.

Next, a method for making the driving force of the first actuator 100A larger than the driving force of the second actuator 100B will be described. FIG. 5 is a diagram showing the frequency characteristic of the first actuator 100A (relationship between the frequency f of the AC voltage and the driving speed V of the lens 12 (lens holding member 13)), and is also the frequency characteristic of the second actuator 100B. In the frequency _{f 1} or frequency region used for driving the first actuator 100A and the second actuator 100B, the driving velocity V in accordance with the frequency f becomes higher the smaller. The frequency f _h is an upper limit frequency at which the first actuator 100A and the second actuator 100B can be driven stably.

To larger than the driving force of the first actuator 100A driving force of the second actuator 100B lowers the drive frequency _{f 1} of the first actuator 100A only Δf than the drive frequency _{f 2} of the second actuator 100B. As a result, the drive speed V1 of the _first movable member 5A is greater than the drive speed V2 of the _second movable member 5B. That is, by making the drive frequency f ₂ higher than the drive frequency f ₁ by Δf (f ₂ = f ₁ + Δf), the drive force of the first actuator 100A can be made larger than the drive force of the second actuator 100B. . Note that in order to make the driving force of the second actuator 100B larger than the driving force of the first actuator 100A, it is only necessary to reverse the relationship between the driving frequencies f ₁ and f ₂ , so detailed description will be omitted. .

In the autofocus control in the imaging apparatus 400, the drive control unit 19 moves the lens 12 while controlling the drive frequencies f ₁ and f ₂ of the AC voltage for driving the first actuator 100A and the second actuator 100B. Then, when the position of the lens 12 reaches the drive target position, the drive control unit 19 stops supplying the AC voltage to the first actuator 100A and the second actuator 100B. In the first actuator 100A and the second actuator 100B, the first movable member 5A is controlled by controlling the frequency and phase difference of the two-phase AC voltage applied to the two-phase electrodes provided in the respective piezoelectric elements 2b. Then, the speed control of the second movable member 5B is performed. Since this control method is well known, its detailed description is omitted.

  Although the case where the frequency characteristic of the first actuator 100A and the frequency characteristic of the second actuator 100B are substantially equal has been described with reference to FIG. 5, the frequency characteristic of the first actuator 100A and the frequency characteristic of the second actuator 100B are different. There is. Then, next, a method for adjusting the magnitude of the driving force when the frequency characteristics of the two vibration actuators are different will be described.

FIG. 6 is a diagram for explaining a frequency correction method for adjusting the driving force of the first actuator 100A and the second actuator 100B. FIG. 6A shows the frequency characteristics before the frequency correction, and FIG. (B) shows the frequency characteristics before frequency correction. Here, the frequency characteristic of the second actuator 100B is higher than the frequency characteristic of the first actuator 100A so that the maximum speed of the second movable member 5B is smaller than the maximum speed of the first movable member 5A. The case of shifting will be taken up. In this case, the relationship between the driving frequency _{f 2max} applying a driving frequency _{f 1max} and maximum speed _{V 2max} of the second movable member 5B which gives the maximum speed _{V 1max} of the first movable member 5A before the frequency _{correction, V 2max} < _V1max , _f1max < _f2max .

In this case, when the first actuator 100A is driven at the drive frequency f ₁ and the second actuator 100B is driven at the drive frequency f ₂ without performing frequency correction, the drive speed V ₁ of the _first movable member 5A and the second driving speed _{V 2} of the movable member 5B is substantially equal _{(V 1} ≒ _{V 2).} In this case, the driving force of the first actuator 100A cannot be made larger than the driving force of the second actuator 100B. Therefore, as shown in FIG. 6 (b), so that the frequency characteristic of the first actuator 100A and the second actuator 100B are substantially equal in the above driving frequency _{f L} of the frequency domain, the frequency characteristic of the second actuator 100B by a broken line Shift as shown. The drive frequency f ₂ of the second actuator 100B is corrected based on the frequency shift amount Δf ₂ at that time, and the second actuator 100B is driven at the corrected frequency f ₂ ′ (= f ₂ + Δf ₂ ). As a result, the driving speed V2 of the _second movable member 5B is smaller than the driving speed V1 of the _first movable member 5A, so that the driving force of the first actuator 100A is greater than the driving force of the second actuator 100B. Can be bigger.

  As described above, in the imaging apparatus 400, when driven in the + X direction, the lens 12 (lens holding member 13) moves following the first movable member 5A without delay and is driven in the -X direction. When moving, the second movable member 5B follows the second movable member 5B without delay. That is, the lens driving device 300 is excellent in responsiveness, and the lens 12 can be driven to the in-focus position without delay, thereby realizing an autofocus mechanism with excellent mobility.

  In the above description, the lens driving device 300 configured using the vibration type actuator 100 in which the vibrating body 2 and the movable member 5 move integrally with the fixed friction member 1 has been described. However, the vibration type actuator used in the lens driving device 300 may be configured such that the friction member 1 and the movable member 5 move integrally with respect to the fixed vibration body 2. Further, when the lens holding member 13 is driven at a constant speed, the driving force of the first actuator 100A and the driving force of the second actuator 100B are the same. However, the present invention is not limited to this, and the relationship between the driving force during acceleration and deceleration. Alternatively, driving at a constant speed may be performed. Further, in the lens driving device 300, the vibration type actuator 100 is used as a driving source, but a stepping motor or a voice coil motor may be used instead.

  With reference to FIGS. 5 and 6, the method of adjusting the magnitude of the driving force by controlling the driving frequency of the first actuator 100A and the second actuator 100B has been described. In contrast, a method for adjusting the magnitude of the driving force by controlling the phase difference between the AC voltages supplied to the first actuator 100A and the second actuator 100B will be described. The difference between adjusting the magnitude of the driving force by the driving frequency or adjusting the phase difference is the difference in the control method in the drive control unit 19, and the configuration of the imaging device 400 including the lens driving device 300 is shown in FIGS. As described with reference to FIG. Therefore, descriptions of the lens driving device 300 and the imaging device 400 are omitted.

FIG. 7 is a diagram illustrating frequency characteristics of the first actuator 100A and the second actuator 100B. The lens 12 (lens holding member 13) moves in the + X direction when the phase difference of the AC voltage applied to each piezoelectric element 2b of the first actuator 100A and the second actuator 100B is positive, and when the phase difference is negative. It is assumed that it is configured to move in the -X direction. When driving the lens holding member 13 in the + X direction, the lens holding member 13 has a maximum speed when the phase difference θ is about +90 degrees, and the speed decreases as the phase difference θ approaches 0 degrees. Therefore, the phase difference theta is in the range of 0 degrees to 90 degrees, setting the phase difference theta ₁ of the first actuator 100A to a value greater than the phase difference theta ₂ of the second actuator 100B. In this case, the drive frequency fd, the driving speed _{V 1} of the first movable member 5A relationship velocity _{V 2} of the second movable member 5B _becomes V 1> _{V 2.} That is, the drive control unit 19 performs phase difference θ ₁ , θ _{2 of} AC voltages supplied to the first actuator 100A and the second actuator 100B for driving during acceleration / deceleration when driving the lens holding member 13 in the + X direction. Is set to a relationship of θ ₁ > θ ₂ . Thereby, the driving force of the first actuator 100A can be made larger than the driving force of the second actuator 100B.

Note that the first actuator 100A and the second actuator 100B have a frequency range f _{L to} f _h in which stable driving is possible. If driving is performed at a frequency outside the frequency range, driving including driving stop is performed. Problems such as instability occur. Accordingly, it is necessary to keep the drive frequencies f ₁ and f ₂ of the first actuator 100A and the second actuator 100B within the frequency range f _{L to} f _h , respectively. When the magnitude of the driving force is adjusted by controlling the driving frequency of the first actuator 100A and the second actuator 100B, the usable frequency range is narrowed by Δf. On the other hand, in the method of adjusting the magnitude of the driving force by setting different values for the phase difference between the AC voltages supplied to the first actuator 100A and the second actuator 100B, the usable frequency range is limited. There is an advantage that it does not.

  Next, a lens driving device according to the second embodiment will be described. In the lens driving device 300 according to the first embodiment, the directions in which the first movable member 5A and the second movable member 5B are urged by the first urging member 16 and the second urging member 26, respectively. Both were configured to be in the -Z direction. However, the present invention is not limited to this, and the movable member in one vibration type actuator may be urged in the + Z direction by the urging member. Hereinafter, the lens driving device according to the second embodiment in which the second movable member 5B is biased in the + Z direction by the second actuator 100B will be described. Note that, in the lens driving device according to the second embodiment, the description of the configuration common to the lens driving device 300 according to the first embodiment is omitted.

FIG. 8A is a front view showing a schematic configuration of a lens driving device 300A according to the second embodiment, and FIG. 8B is a view showing the U-shaped hole 13b of the lens holding member 13 and the guide member 14b. It is the elements on larger scale of a fitting part. In the lens driving device 300A, the second movable member 5B of the second actuator 100B by the second biasing member 26 (not shown), acting biasing force _{F B} in the + Z direction. On the other hand, as shown in FIG. 2, the biasing force F _A in the -Z direction on the first movable member 5A of the first actuator 100A by the first biasing member 16 is acting. As a result, the urging forces L ₁₂ and L ₂₂ are generated in the same direction in the U-shaped hole portion 13b of the lens holding member 13 with respect to the guide member 14b due to the urging forces F _A and F _B.

The urging forces L ₁₂ and L ₂₂ generated in the lens driving device 300A are compared with the urging forces generated due to the urging forces F _A and F _B in the lens driving device 300 according to the first embodiment. FIG. 9A is a front view for explaining the urging force acting on the lens holding member 13 by the first urging member 16 and the second urging member 26 in the lens driving device 300, and shows the first actuator 100A. The illustration is omitted. FIG. 9B is a front view of a fitting portion between the U-shaped hole 13b of the lens holding member 13 and the guide member 14b. In the lens driving device 300, the second biasing member 26 acts on the receiving surface 13d of the lens holding member 13, urges the lens holding member 13 in the arrow _{J 2} direction. Accordingly, a rotational force in the direction of arrow K is applied to the lens holding member 13 around the point I (the central axis of the guide member 14a), and an urging force L that urges the U-shaped hole 13b against the guide member 14b. ₂₁ is produced. Similarly, the lens holding member 13 is urged in the direction of the arrow J1 by a _first urging member 16 (not shown), and accordingly, an urging force L ₁₁ that urges the U-shaped hole 13b against the guide member 14b. Occurs. In the urging forces L ₁₁ and L ₂₁ , the direction acting on the U-shaped hole 13 b is reversed. In this case, the guide member 14b is formed in the U-shaped hole 13b due to variations in characteristics of the first urging member 16 and the second urging member 26, component tolerances and assembly tolerances of various components constituting the lens driving device 300, and the like. Which of the surfaces 13f and 13g abuts is different.

On the other hand, in the lens driving device 300A, since the urging forces L ₁₂ and L ₂₂ are generated in the same direction, the U-shaped hole portion 13b is placed on the guide member 14b so that the guide member 14b and the surface 13g come into contact with each other. It is energized in one direction. Therefore, the position of the lens holding member 13 and the lens 12 on the YZ plane can be determined stably even if there are part tolerances, assembly tolerances, and the like in various parts constituting the lens driving device 300A. That is, in the lens driving device 300A, by aligning the direction of the urging force generated in the lens holding member 13 by the first urging member 16 and the second urging member 26, the lens holding member 13 is moved relative to the guide member 14b. There is an advantage that it can be reliably energized.

Next, a lens driving device according to a third embodiment will be described. In the lens driving apparatus 300 according to the first embodiment, the biasing force F _A that the first biasing member 16 caused by the second biasing member 26 has _been described substantially equal configuration the size of the F _B. On the other hand, in the lens driving device according to the third embodiment, a difference is provided in the magnitudes of the urging forces F _A and F _B. Note that in the lens driving device according to the third embodiment, the description of the configuration common to the lens driving device 300 according to the first embodiment is omitted.

FIG. 10A is a front view for explaining the urging force acting on the lens holding member 13 by the first urging member 16 and the second urging member 26A in the lens driving device 300B according to the third embodiment. . FIG. 10B is a plan view of the first urging member 16 and the second urging member 26A. FIG. 10C is a front view of a fitting portion between the U-shaped hole 13b of the lens holding member 13 and the guide member 14b. The urging force F _A acting on the first movable member 5A by the first urging member 16 and the urging force F _B acting on the second movable member 5B by the second urging member 26A are both the same. -Z direction. Therefore, as described with reference to FIG. 9, the urging force that the first urging member 16 and the second urging member 26A respectively apply the U-shaped hole 13b of the lens holding member 13 to the guide member 14b. The directions of L ₁₃ and L ₂₃ are opposite to each other.

Here, the second urging member 26 </ _b > _A has a wire diameter larger than that of the first urging member 16 so that the relationship of “F _A <F _B ” is established between the urging forces F _A and F _B. Consists of materials. The first biasing member 16 and the second biasing member 26A are not limited to the direction of changing the wire diameter. For example, by changing the material, the relationship “F _A <F _B ” is established. It doesn't matter. As a result, the relationship of “L ₁₃ <L ₂₃ ” is established between the urging forces L ₁₃ and L ₂₃ , and the guide member 14 b comes into contact with the surface 13 f of the U-shaped hole portion 13 b. In this way, the position of the lens holding member 13 and the lens 12 on the YZ plane can be determined stably even if component tolerances, assembly tolerances, and the like occur in the various components constituting the lens driving device 300B.

  Although the present invention has been described in detail based on preferred embodiments thereof, the present invention is not limited to these specific embodiments, and various forms within the scope of the present invention are also included in the present invention. included. Furthermore, each embodiment mentioned above shows only one embodiment of this invention, and it is also possible to combine each embodiment suitably.

DESCRIPTION OF SYMBOLS 1 Friction member 2 Vibrating body 4 Pressure member 5A 1st movable member 5B 2nd movable member 13 Lens holding member 15 1st connection member 16 1 biasing member 19 Drive control part 20 Lens barrel 21 Imaging element 25 Second connecting member 26 Second urging member 100A First vibration type actuator (first actuator)
100B Second vibration type actuator (second actuator)
300, 300A, 300B Lens driving device 400 Imaging device

Claims (13)

A driven member;
A first drive source;
A first connecting member that connects the first driving source and the driven member, and that transmits a driving force of the first driving source to the driven member;
A second drive source;
A second connecting member for connecting the second driving source and the driven member, and transmitting a driving force of the second driving source to the driven member;
First urging means for urging the first connecting member in a first direction with respect to the driven member to press-contact the first connecting member and the driven member;
Second urging means for urging the second connecting member in a direction opposite to the first direction with respect to the driven member to press-contact the second connecting member and the driven member. A linear drive device comprising: Control means for controlling the driving force generated by the first driving source and the second driving source;
The control means includes
When the driven member is driven in the first direction, a driving force for driving the first connecting member in the first direction by the first driving source is generated by the second driving source. Greater than the driving force for driving the second connecting member in the first direction;
When the driven member is driven in the opposite direction, a driving force for driving the second connecting member in the opposite direction by the second driving source is used by the first driving source. The linear driving device according to claim 1, wherein the driving force is greater than the driving force for driving the connecting member in the first direction.   When the driven member is driven at a constant speed, the control means drives the first connecting member in the first direction with the first driving source and the second driving. The linear drive device according to claim 2, wherein a driving force for driving the second connecting member in the first direction with a source is made substantially equal. The first drive source has a first movable member coupled to the first coupling member,
The second drive source has a second movable member coupled to the second coupling member,
The control means controls driving of the first connecting member and the second connecting member by controlling driving of the first movable member and the second movable member. The linear drive device according to 2 or 3. Each of the first drive source and the second drive source is a vibration actuator,
The vibration type actuator is
A vibrating body in which an elastic body and an electromechanical energy conversion element are joined;
A friction member in pressure contact with the vibrator;
A pressure member that pressurizes and contacts the vibrating body and the friction member;
In each of the first drive source and the second drive source, the first movable member and the second drive member are moved by relative movement between the vibration member and the friction member caused by vibration excited by the vibration member. The linear drive device according to claim 4, wherein the movable member is driven. A guide member for guiding the driven member in the first direction;
The driven member has a fitting portion that fits slidably with the guide member;
The first urging means urges the first connecting member in a second direction perpendicular to the first direction with respect to the first movable member, and the second urging means The second linking member is urged with respect to the second movable member in a direction substantially parallel to the second direction, and the first urging means and the second urging means are driven. The linear drive device according to claim 5, wherein the fitting portion is brought into contact with the guide member by urging the member in a predetermined direction.   In each of the first drive source and the second drive source, a pressurizing direction in which the pressurizing member pressurizes and contacts the vibrating body and the friction member is substantially parallel to the second direction. The linear drive device according to claim 6.   The second biasing means biases the second connecting member in a direction opposite to the second direction with respect to the second movable member. Linear drive device. The second urging means urges the second connecting member in the second direction with respect to the second movable member,
The first urging means urges the first connecting member in the second direction with respect to the first movable member, and the second urging means has the second urging means. The linear drive device according to claim 6, wherein the urging force for urging the second connecting member in the second direction with respect to the movable member is different.   The control means sets different frequencies for the AC voltage supplied to each of the electro-mechanical energy conversion element of the first drive source and the electro-mechanical energy conversion element of the second drive source, 10. The linear drive device according to claim 5, wherein magnitudes of driving forces of the first movable member and the second movable member are adjusted.   The control means is configured to supply two-phase AC voltage having a predetermined phase difference between the electro-mechanical energy conversion element of the first drive source and the electro-mechanical energy conversion element of the second drive source. And adjusting the magnitudes of the respective driving forces of the first movable member and the second movable member by setting different values for the phase difference. The linear drive device of any one of these. A lens,
A linear drive device according to any one of claims 1 to 11,
The lens barrel, wherein the driven member included in the linear driving device is a lens holding member that holds the lens, and the first direction is substantially parallel to an optical axis direction of the lens. The lens barrel according to claim 12,
An image pickup device comprising: an image pickup device that forms an image of a light beam that has passed through the lens barrel and converts an optical image into an electric signal.