JP4590482B2 - Drive device, imaging device including the same, and electronic apparatus - Google Patents

Description

  The present invention relates to a driving device, an imaging device including the driving device, and an electronic apparatus.

  Conventionally, a driving device for driving a driven body using an electromechanical conversion element (piezoelectric element) has been proposed. Such a driving device is used for driving a lens in an optical device such as a photographing lens of a camera, for example.

  For example, in Patent Document 1, a piezoelectric element that is bent by voltage application, a holding member that holds one end of the piezoelectric element, a driven body that is in frictional contact with the free end of the piezoelectric element, and the piezoelectric element and the driven body are fixed. And a preload mechanism for pressing with a force of the above, and an invention relating to a drive device that moves a driven body that is in frictional contact by bending displacement of a piezoelectric element is disclosed.

JP 2007-252103 A (published September 27, 2007)

  However, since the driving device disclosed in Patent Document 1 requires a preload generating member such as a spring and a sliding member such as a bearing to smoothly move the driven body, it is difficult to reduce the size of the device. Met. Moreover, in patent document 1, the detailed description about the preload mechanism is not made. Furthermore, there was not enough space in the drive device disclosed in Patent Document 1 to provide a preload mechanism.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a simple preload mechanism in a small space, and a frictional force acting between a driving member and a driven body. Another object of the present invention is to provide a drive device in which the drive speed of the driven body is stable.

  Another object of the present invention is to provide a driving device that can smoothly drive a driven body and that can be downsized.

  In order to solve the above-described problems, the drive device according to the present invention has an end portion fixed to the casing, and an electromechanical transducer element in which bending displacement is caused by electrical control, and an end portion of the electromechanical transducer element. A friction member in which the other end is in frictional contact with the driven body, one end is held by the driven body, and the other end is held by the housing. And a preload member that biases the driving body in a direction in which the driving body is in frictional contact with the friction member.

  According to said structure, an electromechanical conversion element can be bent by electrical control, and a to-be-driven body can be moved to a fixed direction via a friction member. Further, since one end portion of the preload member is held by the driven body and the other end portion is held by the casing, the preload member is displaced by the movement of the driven body. Thereby, the structure of the drive device can be simplified and the function can be further stabilized. That is, a simple preload mechanism can be provided in a small space, and a driving device in which the frictional force acting between the driving member and the driven body and the driving speed of the driven body are stable can be provided. . Further, it is possible to provide a drive device that can smoothly drive the driven body and that can be downsized.

  In the drive device according to the present invention, it is more preferable that the preload member is a tension coil spring.

  According to said structure, since a tension coil spring has the outstanding elasticity, the more stable preload effect can be achieved in the movement process of a to-be-driven body. Further, it is possible to reduce the load in the direction in which the driven body is driven, and stable driving is possible.

  In the drive device according to the present invention, the driven body includes a friction contact portion that frictionally contacts the friction member, and a holding portion that holds one end of the preload member. More preferably, the preload member is positioned between the two portions.

  According to said structure, since the space in a drive device can be utilized effectively, size reduction of a drive device is attained.

  In the drive device according to the present invention, the driven body includes a friction contact portion that frictionally contacts the friction member, and a holding portion that holds one end of the preload member. More preferably, the friction member is positioned between the two portions.

  According to the above configuration, since the friction contact portion to which the friction force is applied and the holding portion to which the preload is applied can be provided close to each other in the driven body, the movement of the driven body can be performed more stably. Can do.

  Furthermore, in the driving device according to the present invention, the tension coil spring includes an effective spring portion at a central portion thereof, and has a diameter smaller than a diameter of the effective spring portion at one end or both ends of the effective spring portion. A second end having a diameter larger than the diameter of the first end, and the first end is fitted into at least one of the driven body and the housing. It is more preferable that the second end is held by being hooked.

  According to the above configuration, for example, even when a small-diameter tension coil spring that cannot form hook portions at both ends is used as the preload member, the drive device can be easily assembled with a simple configuration.

  In the driving device according to the present invention, it is more preferable that the first end portion and the second end portion are wound tightly without elasticity.

  According to said structure, holding | maintenance of the 1st end part and 2nd end part by at least one of a to-be-driven body and a housing | casing can be stabilized more.

  In the driving apparatus according to the present invention, it is more preferable that the preload member is a torsion coil spring.

  According to said structure, since a torsion coil spring has the outstanding elasticity, the more stable preload effect can be achieved in the movement process of a to-be-driven body. Further, the drive device can be further downsized.

  In the drive device according to the present invention, it is more preferable that a fixing member is provided between the electromechanical conversion element and the friction member.

  According to said structure, the preload load with respect to the to-be-driven body by a preload member can be stabilized more.

  In the driving apparatus according to the present invention, it is more preferable that the fixing member is configured to make the moving direction of the friction member different from the driving direction of the electromechanical conversion element.

  According to the above configuration, since the degree of freedom increases in the arrangement of the electromechanical conversion elements in the housing, the outer size of the housing, that is, the size of the driving device can be further reduced.

  The drive device according to the present invention is determined in advance according to the increase / decrease amount of the load generated in the moving direction of the driven body in accordance with the positional displacement of the driven body that moves due to the bending displacement of the electromechanical conversion element. More preferably, it further comprises drive control means for outputting a drive signal to the electromechanical transducer.

  According to the above configuration, the drive control means outputs a predetermined drive signal to the electromechanical conversion element in accordance with the load increase / decrease amount generated in the moving direction of the driven body. Regardless, the driving distance of the driven body that moves by the bending displacement per electromechanical conversion element can be controlled to be constant. For this reason, the accuracy of the drive distance per drive can be further improved regardless of the increase / decrease amount of the load generated in the moving direction of the drive.

  In the driving apparatus according to the present invention, the driving signal is more preferably a pulsed driving signal.

  According to the above configuration, the driving distance per driven body can be controlled by adjusting the number of pulses of the driving signal, so that the accuracy of the driving distance can be further improved.

  In order to solve the above-described problems, an imaging apparatus according to the present invention includes the above driving device.

  According to the above configuration, it is possible to provide a more accurate imaging device with a more stable driving speed.

  In order to solve the above-described problems, an electronic apparatus according to the present invention includes the drive device or the imaging device.

  According to the above configuration, it is possible to provide a more precise electronic device with a more stable driving speed and higher accuracy.

  The drive device according to the present invention has one end fixed to the housing, an electromechanical conversion element in which bending displacement is caused by electrical control, one end connected to the electromechanical conversion element, and the other end A friction member that is in frictional contact with the driven body, one end portion is held by the driven body and the other end portion is held by the housing, and the driven body is in frictional contact with the friction member. And a preload member for urging in the direction of movement.

  Thereby, the structure of the drive device can be simplified and the function can be further stabilized. That is, even without using a sliding member such as a bearing, it is possible to realize a structure with less variation in the preload load on the driven body and less resistance change with respect to the moving operation of the driven body as compared with the prior art. That is, a simple preload mechanism can be provided in a small space, and a driving device in which the frictional force acting between the driving member and the driven body and the driving speed of the driven body are stable can be provided. . Further, it is possible to provide a drive device that can smoothly drive the driven body and that can be downsized. For example, when the driving device according to the present invention is used for driving a lens of an imaging device such as a camera, a more compact product with a more uniform driving speed and better focus adjustment accuracy is provided. be able to.

It is a schematic plan view which shows the structure of the drive device in Embodiment 1 of this invention. It is the schematic side view which shows the structure of the said drive device, (a) shows the state in which a to-be-driven body exists in the bottom dead center of a drive stroke, (b) is the top dead center of a drive stroke. Shows the state. It is a schematic plan view which shows the structure of the drive device in Embodiment 2 of this invention. FIG. 4 is a schematic side view showing the configuration of the drive device of FIG. 3. FIG. 4 is a schematic side view showing the configuration of the drive device of FIG. 3, (a) shows a state in which the driven body is at the bottom dead center of the drive stroke, and (b) shows a state in which the driven body is above the drive stroke. Indicates the state at the dead center. It is a schematic plan view which shows the structure of the drive device in Embodiment 3 of this invention. FIG. 7 is a schematic side view showing the configuration of the drive device of FIG. 6, (a) shows a state where the driven body is at the bottom dead center of the drive stroke, and (b) shows a state where the driven body is above the drive stroke. Indicates the state at the dead center. It is a schematic plan view which shows the structure of the drive device in Embodiment 4 of this invention. FIGS. 9A and 9B are schematic side views showing the configuration of the drive device of FIG. 8, in which FIG. 9A shows a state where the driven body is at the bottom dead center of the drive stroke, and FIG. Indicates the state at the dead center. It is a schematic plan view which shows the structure of the drive device in Embodiment 5 of this invention. It is a schematic perspective view which shows the structure of the drive device of FIG. It is a schematic perspective view which shows the structure of the drive device of FIG. It is a schematic plan view which shows the structure of the drive device in Embodiment 6 of this invention. It is a schematic plan view which shows the structure of the drive device in Embodiment 7 of this invention. It is a schematic perspective view which shows the structure of the drive device of FIG. (A)-(c) is a schematic side view for demonstrating the positional displacement of the front-end | tip of a friction member in the drive device of this invention. (A), (b) is a graph for demonstrating the movement principle of the to-be-driven body in the drive device of this invention. It is a block diagram which shows the drive control means with which the drive device of this invention is provided. (A)-(c) is a graph for demonstrating the control method of the moving distance of the to-be-driven body performed by the drive control means with which the drive device of this invention is provided.

  The embodiment of the present invention will be described with reference to FIGS. 1 to 18 as follows.

[Embodiment 1]
FIG. 1 is a schematic plan view showing the configuration of the drive device according to Embodiment 1, and FIG. 2 is a schematic side view showing the configuration of the drive device.

  In the following description, the direction of movement of the driven body is the z direction, the length direction of the electromechanical transducer element in the stationary state is perpendicular to the z direction, and the direction perpendicular to the y direction and the z direction is the y direction. The x direction is assumed.

  As shown in FIGS. 1 and 2, the drive device according to the present embodiment has a driven body 2 and one end fixed to a housing 6, and an electromechanical conversion element 5 in which bending displacement is caused by electrical control. A friction member 3 having one end connected to the electromechanical transducer 5 and the other end in frictional contact with the driven body contact portion 2a of the driven body 2, and the electromechanical transducer 5 The fixed member 4 provided between the friction member 3 and one end thereof are fixed to the driven body contact portion 2a, and the other end is fixed to the casing 6, and the driven body contact And a preload member 1 that urges the portion 2a in a direction to contact the friction member 3.

  The housing 6 has a frame structure including the preload member 1, the electromechanical conversion element 5 and the like therein, and is for securing the strength and function of the driving device. For example, when the driving device of the present invention is built in an electronic device or the like, and the preload member 1, the electromechanical transducer 5 or the like is directly provided on the electronic device body, the electronic device body may be regarded as the housing 6. it can.

  The electromechanical transducer 5 is arranged perpendicular to the side wall of the housing 6. The fixed end (one end portion) of the electromechanical conversion element 5 and the other end portion of the preload member 1 are fixed to the housing 6. Accordingly, the movement of the driven body 2 changes the relative position between the driven body 2 and the housing 6, and the relative position between the driven body 2, the electromechanical conversion element 5, and the preload member 1 also changes.

  The guide member 6a provided in the housing 6 has a guide structure for smoothly moving the driven body 2 along the z direction. Note that the guide member 6 a may have a configuration in which, for example, a shaft provided perpendicular to the bottom surface of the housing 6 is passed through a shaft hole provided in the driven body 2.

  The driven body 2 is always urged toward the electromechanical conversion element 5 by the preload member 1. For this reason, the driven body 2 can maintain a stable position. For example, when the drive device according to the present invention is applied to a portable electronic device such as a mobile phone, the electronic device is highly likely to receive an impact due to dropping or the like. For this reason, when the drive device of the present invention is used in such an electronic apparatus, the position of the driven body 2 is kept stable by using the guide member 6 a, that is, the driven body 2 is in the housing 6. It is more effective to prevent it from coming off.

  The friction member 3, the fixing member 4 and the electromechanical conversion element 5 constitute a drive mechanism. When the electromechanical conversion element 5 is bent, the driven body 2 is moved according to the guide member 6a provided in the housing 6. It moves in the z direction.

  The preload member 1 and the friction member 3 are arranged with the driven member contact portion 2 a interposed therebetween, and are always attached in a direction in which the driven member contact portion 2 a of the driven member 2 contacts the friction member 3 by the preload member 1. It is energized.

  One end of the preload member 1 is fixed to the driven body contact portion 2 a of the driven body 2 and the other end is fixed to the housing 6. For this reason, when the driven body 2 moves, the preload member 1 also moves together and deforms accordingly.

  The preload member 1 is preferably a coil spring or a member having elasticity, such as a coil spring. In the case of a coil spring, it is more preferable that one end or both ends of the preload member 1 be tightly wound without elasticity.

  The effects when the coil spring is tightly wound are as follows.

  If one end or both ends of the coil spring are tightly wound with no elasticity, when the coil spring is fixed to the casing 6 or the driven body 2 using an adhesive or the like, a large area for applying the adhesive is secured. Can do. Moreover, since the range to be fixed does not vary due to manufacturing tolerances or the like by using the tight winding, a stable preload can be obtained.

  As another configuration for fixing the coil spring wound tightly to the casing 6 or the driven body 2, a concave or convex portion for fixing the coil spring is provided on the driven body 2, and the casing 6 has a coil spring. It is also possible to provide a configuration in which a concave portion or a hole portion is provided for fixing the coil spring and an adjustment mechanism for fixing the coil spring at each of these portions and adjusting the pressing force (preload load) with a screw or the like is provided. In order to mass-produce the drive device according to the present invention, it is necessary to appropriately adjust the pressing force of the preload member 1. For this reason, if it is set as the structure which adjusts the pressing force of the preload member 1 with a screw etc., a highly productive drive device is realizable.

  The friction member 3 is connected to the free end side of the electromechanical transducer 5 and moves along with the bending of the electromechanical transducer 5. The driven body 2 is moved by the action of the frictional force acting between the friction member 3 and the driven body contact portion 2a. As the material of the friction member 3, a suitable material may be selected in consideration of the friction coefficient with the driven body contact portion 2a, and examples thereof include metals, resins, and carbon.

  The fixing member 4 is provided between the electromechanical conversion element 5 and the friction member 3, and is preferably a material or shape having a lower elasticity than the preload member 1, and examples thereof include metals and resins. . By making the elastic effect of the fixing member 4 lower than that of the preload member 1, the driven member contact portion 2a is uniformly biased in the direction in contact with the friction member 3, so that the driven member 2 can be stabilized. Can be moved.

  The electromechanical conversion element 5 is a bimorph type piezoelectric element, and is configured, for example, by forming a laminated piezoelectric element on both sides or one side of a metal plate. The electromechanical conversion element 5 only needs to have a degree of bending displacement necessary to maintain a normal function that the drive device should have. Therefore, the configuration and shape of the electromechanical transducer 5 are not limited to a specific configuration or shape.

  One end portion of the electromechanical conversion element 5 is bonded or fitted to the housing 6 to be a fixed end, and the other end portion is a free end, and is connected to the fixed member 4 provided with the friction member 3. ing. When a voltage is applied to the electromechanical transducer 5, the free end of the electromechanical transducer 5 is bent and displaced in the z direction, and the friction member 3 is also displaced in the z direction. Then, the driven body 2 moves in the z direction due to the frictional force between the driven body contact portion 2 a and the friction member 3 generated by the preload load of the preload member 1.

  When the driving device according to the present invention is applied to a camera module (lens driving of an imaging device such as a camera), the driven body 2 becomes a lens barrel having an annular lens mounting portion at the center thereof, By driving in the optical axis direction (z direction) by a drive mechanism including the friction member 3 and the electromechanical conversion element 5, an AF (autofocus) operation of the lens attached to the lens attaching portion is realized.

  Here, as shown in FIG. 2, a line passing through the center of the friction member 3 and parallel to the y direction is defined as a preload perpendicular. The force generated by the preload member 1 is applied to the driven body 2 in the same direction as the preload perpendicular, and becomes a preload load between the friction member 3 and the driven body 2. Further, when the driven body 2 moves in the z direction, the preload member 1 is simultaneously deformed in its own central axis direction (length direction) and z direction from the stationary state. The state in which the preload member 1 (coil spring) is most compressed in the central axis direction is defined as the most compressed state, and the state in which the preload member 1 is most expanded in the central axis direction is defined as the most expanded state. The preload member 1 is fixed so that the length direction of the preload member 1 when reaching the maximum extension state (maximum operating point) is not perpendicular to the z direction. One end of the preload member 1 fixed to the driven body contact portion 2a of the driven body 2 moves with the movement of the driven body 2 and is within the maximum movement range (driving stroke). The one end portion is fixed so that there is a position located on the preload perpendicular.

  A driving method of the driven body 2 in the driving apparatus according to the present invention will be described as follows.

  In the driving device of the present invention, the voltage applied to the electromechanical transducer 5 is controlled so that the reciprocating bending speed of the electromechanical transducer 5 is different, and the friction acting between the driven body 2 and the friction member 3 is controlled. By changing the force according to the speed difference, a frictional movement difference is generated to change the displacement amount (movement amount) of the driven body 2 in the z direction. The driven body 2 is between the bottom dead center where the preload member 1 (coil spring) is in the most compressed state and the top dead center (maximum operating point) where the preload member 1 is in the most extended state. Move back and forth (within the movement range).

  2A shows a state in which the driven body 2 is at the bottom dead center within the maximum movement range (driving stroke), and FIG. 2B shows that the driven body 2 is at the top dead center in the driving stroke. Indicates the state.

  For example, assuming that the driven body 2 is at the bottom dead center (the state shown in FIG. 2A), the driven body 2 is deformed by the bending displacement of the electromechanical conversion element 5 as shown in FIG. It will move suitably between FIG.2 (b). In addition, in the state of FIG.2 (b), you may provide the contact part which contacts the to-be-driven body 2 in the housing | casing 6 so that the to-be-driven body 2 may not move further beyond a drive stroke.

  The effects obtained by providing the fixing member 4 will be described as follows.

  When the coil spring (preload member 1) is in the most compressed state, the preload is the largest (FIG. 2 (a)). As the preload increases, the frictional force between the guide member 6a and the driven body 2 increases at the same time, so that the movement resistance of the driven body 2 increases. Here, in order to stabilize the driving speed and thrust of the driven body 2, it is desirable that the fluctuation of the preload is small.

  The variation of the preload is related to the spring constant of the coil spring. Here, by arranging the elastic fixing member 4 between the friction member 3 and the electromechanical conversion element 5, it is possible to obtain an effect of reducing fluctuations in the preload depending on the spring constant of the fixing member 4. it can.

When the spring constant of the coil spring is k1 and the spring constant of the fixing member 4 is k4, the fluctuation of the preload is assumed to be a new spring constant k ′.
1 / k ′ = (1 / k1) + (1 / k4)
It is represented by

  In FIG. 1 and FIG. 2, etc., the fixing member 4 and the electromechanical transducer 5 are configured as separate members. However, in the case of separate members, fixing with an adhesive or the like is necessary, and this fixing portion is relatively unstable. Therefore, when the number of times of driving is increased or the preload is increased, it is fixed. There is a risk of damage. Therefore, the fixing member and the electromechanical conversion element may be integrally configured by deforming the metal plate on the free end side of the electromechanical conversion element 5 into the same configuration as that of the fixing member 4. When the same member is used, stable driving can be maintained regardless of the number of times of driving, and stable driving can be maintained regardless of the magnitude of the preload.

  In the present embodiment, the driven body contact portion 2 a is configured as a part of the driven body 2. However, the driven body contact portion 2a may be a separate member from the driven body 2. That is, the structure to which the to-be-driven body contact part 2a which is another member was attached to the to-be-driven body 2 may be sufficient. In general, the driven body 2 is made of resin. However, by using the driven body contact portion 2a as a separate member, a suitable material can be selected in consideration of the friction coefficient with the friction member 3 regardless of the material of the driven body 2. Specifically, for example, a metal, carbon, or the like can be selected as the material of the driven body contact portion 2a.

  By the way, before and after the most compressed state, the direction of the preload in the z direction of the coil spring is reversed, so that a point where the moving speed rapidly changes during the movement of the driven body 2 in the same direction is created. Therefore, when this driving device is applied to a camera module, it causes a problem in the AF operation of the lens.

  Therefore, when a coil spring is used as the preload member 1, it may be fixed as follows. That is, if the coil spring is fixed to the driven body contact portion 2a of the driven body 2 and the housing 6 so as to be in the most compressed state at the top dead center or the bottom dead center of the driven body 2 moving stroke. Good.

Further, it is preferable that the coil spring has sufficiently small (soft) lateral rigidity (in the case of the present embodiment, rigidity in the substantially z direction). When the average diameter and the wire diameter of the coil spring are the same, the longer the free length, the smaller the spring constant and the lateral rigidity. However, when the lateral rigidity is too small, when the coil spring is deformed as the driven body 2 is moved, buckling occurs due to the amount of deformation. When buckling occurs, the buckling mode changes, or the preload load changes abruptly, a point where the moving speed changes abruptly during the movement of the driven body 2 in the same direction is created. Therefore, when this driving device is applied to a camera module, it causes a problem in the AF operation of the lens. Therefore, when the preload member 1 is a coil spring, the following conditional expression δ × L0 / (D2) ≦ 7
(However, the free length of the coil spring: L0, the average diameter of the coil spring: D, the amount of deformation in the central axis direction of the coil spring in the most compressed state: δ)
It is desirable to use a coil spring that satisfies the above.

  Further, when the coil spring is in the most compressed state at either the top dead center or the bottom dead center (in this embodiment, the bottom dead center), the central axis direction is not parallel to the preload perpendicular. As described above, it is more preferable that the coil spring is tilted by offsetting one end thereof. The direction of the offset is that when the coil spring is in the most compressed state at the top dead center, the end of the coil spring fixed to the housing 6 is offset upward, and the coil spring is in the most compressed state at the bottom dead center. When it becomes, it is good to make the offset of the edge part of the coil spring fixed to the housing | casing 6 down. By offsetting, even if there is a manufacturing error or assembly error in each member, when the coil spring moves and deforms as the driven body 2 moves, it further moves beyond the most compressed state and deforms. This can be surely prevented. Even if buckling occurs, the influence of buckling can be minimized by making the buckling direction constant.

Since one end of the coil spring moves together with the driven body 2, the magnitude of the preload varies with a change in the angle formed by the preload perpendicular and the central axis of the coil spring. However, it is preferable that the magnitude of the preload is less changed due to the movement of the driven body 2 (variation rate is 10% or less). For this purpose, the following conditional expression L0 × 0.35 ≧ s
(However, free length of coil spring: L0, movement stroke of driven body 2: s)
Using a coil spring that satisfies the following condition: L0 × 0.15 ≧ d
(However, free length of coil spring: L0, offset amount of end of coil spring: d)
It is desirable to fix the coil spring to the driven body 2 so as to satisfy the above.

[Embodiment 2]
FIG. 3 is a schematic plan view showing the configuration of the drive device according to the second embodiment, and FIGS. 4 and 5 are schematic side views showing the configuration of the drive device.

  In the following description, the moving direction of the driven body is the z direction, the length direction of the electromechanical transducer element in the stationary state is perpendicular to the z direction, and the direction perpendicular to the z direction and the x direction is the x direction. The y direction is assumed.

  FIG. 5A shows a state where the driven body 2 is at the bottom dead center of the driving stroke, and FIG. 5B shows a state where the driven body 2 is at the top dead center of the driving stroke.

  As shown in FIGS. 3 to 5, the drive device in the present embodiment includes a driven body 2, an electromechanical conversion element 5, a friction member 3, a fixing member 4, a preload member 1, and a housing 6. It has. The friction member 3, the fixed member 4 and the electromechanical conversion element 5 constitute a drive mechanism, and the friction member 3 and the fixed member 4 constitute a drive direction conversion member. When the electromechanical conversion element 5 is bent, the driven body 2 is moved in the z direction according to the guide member 6 a provided in the housing 6.

  3 to 5 and the like, the friction member 3 and the fixing member 4 are configured as separate members. However, the friction member and the fixed member may be integrally formed.

  The electromechanical conversion element 5 of the drive device in the present embodiment is disposed in parallel to the side wall of the housing 6. Since the electromechanical conversion element 5 is disposed along the side wall of the housing 6, the outer size of the housing 6, that is, the size of the driving device can be further reduced.

  The free end of the electromechanical transducer 5 is bent and displaced in a direction parallel to the y direction. The fixing member 4 is connected to the electromechanical conversion element 5 and is connected to the friction member 3. The fixing member 4 is configured to make the moving direction of the friction member 3 different from the driving direction of the electromechanical conversion element 5. That is, the fixing member 4 changes the driving direction of the electromechanical conversion element 5 so that the moving direction of the friction member 3 becomes parallel to the z direction, whereby the friction member 3 moves the driven body 2 to the z direction. Drive in the direction. In the present embodiment, the fixing member 4 is preferably made of a leaf spring.

  As shown in FIG. 4, the fixing member 4 is formed in an “L” shape, for example, and is fixed to the free end of the electromechanical transducer 5. Further, the friction member 3 is fixed to the tip end portion of the fixing member 4 in the z direction.

  Since the other configuration of the drive device in the present embodiment is the same as the configuration of the drive device in the first embodiment, the description thereof is omitted.

  A driving method of the driven body 2 in the driving apparatus according to the present invention will be described as follows.

  With the bending displacement of the electromechanical transducer 5, the fixing member 4 is in a direction perpendicular to the direction of the bending displacement (y direction) of the electromechanical transducer 5 (y direction) while the friction member 3 and the driven body 2 are in contact with each other. bending displacement in the z direction). As a result, the friction member 3 operates so as to rotate about the x direction with respect to the driven body 2, and the driven body 2 moves in the z direction.

  The preload member 1 of the drive device according to the present invention is in the most compressed state at the top dead center or the bottom dead center of the moving stroke of the driven body 2, similarly to the preload member 1 of the drive device in the first embodiment. In addition to being fixed to the driven body contact portion 2a and the housing 6 of the driven body 2, the end of the coil spring fixed to the driven body 2 is inclined so as not to be positioned on the preload perpendicular line. It is more preferable to do this.

[Embodiment 3]
FIG. 6 is a schematic plan view showing the configuration of the drive device according to Embodiment 3, and FIG. 7 is a schematic side view showing the configuration of the drive device.

  In the following description, the moving direction of the driven body is the z direction, the length direction of the electromechanical transducer element in the stationary state is perpendicular to the z direction, and the direction perpendicular to the z direction and the x direction is the x direction. The y direction is assumed.

  FIG. 7A shows a state where the driven body 2 is at the bottom dead center of the driving stroke, and FIG. 7B shows a state where the driven body 2 is at the top dead center of the driving stroke.

  As shown in FIGS. 6 and 7, the drive device in the present embodiment includes a driven body 2, an electromechanical conversion element 5, a friction member 3, a fixing member 4, a preload member 1, and a housing 6. And a support member 7.

  A plurality of support elastic members 7 are attached to the housing 6 so as to be rotationally symmetric with respect to the driven body 2, and support the driven body 2 and move the driven body 2 in the moving direction (z direction). It is supposed to be energized. The supporting elastic member 7 is made of a leaf spring.

  Since the other configuration of the drive device in the present embodiment is the same as the configuration of the drive device in the first embodiment, the description thereof is omitted.

  The leaf spring (support elastic member 7) moves as the driven body 2 moves from the bottom dead center to the top dead center (when moving from the position of FIG. 7A to the position of FIG. 7B). A z-direction force that resists the movement is applied to the driven body 2, and as the driven body 2 moves from the top dead center to the bottom dead center (from the position of FIG. 7B to FIG. 7A). When moving to a position), a force in the z direction that promotes the movement is applied to the driven body 2. That is, the moving direction of the driven body 2 accompanied by deformation from the stationary state of the coil spring (preload member 1) and the biasing direction of the leaf spring (support elastic member 7) are different from each other. This force alone causes a difference in the moving speed of the driven body 2 in the reciprocation.

  On the other hand, the coil spring (preload member 1) is moved to the maximum position as the driven body 2 moves from the bottom dead center to the top dead center (when moving from the position shown in FIG. 7A to the position shown in FIG. 7B). Since the compression state shifts to the maximum extension state, a force in the z direction that promotes the movement is applied to the driven body 2, and the driven body 2 moves from the top dead center to the bottom dead center (FIG. 7 ( When moving from the position b) to the position shown in FIG. 7A), since the transition is from the most extended state to the most compressed state, a z-direction force that resists the movement is applied to the driven body 2. .

  That is, in the driving apparatus according to the present embodiment, the coil spring and the leaf spring are arranged so that the force that the coil spring applies to the driven body 2 and the force that the leaf spring applies to the driven body 2 cancel each other. . Thereby, the situation where the moving speed in the reciprocation of the to-be-driven body 2 differs can be relieved. However, it is preferable that the elasticity of the leaf spring is sufficiently weak compared to the elasticity of the coil spring so that the driven body 2 can be moved arbitrarily.

  Further, the cause of the difference in the reciprocating speed of the driven body 2 is not limited to the change in the force applied to the driven body 2 by the coil spring (preload member 1). For example, when the drive device according to the present invention is applied to an imaging device such as a monitoring camera, the imaging device is always affected by gravity in a certain direction. Therefore, in this case, the force that the coil spring applies to the driven body 2 and the force that the leaf spring applies to the driven body 2 in consideration of the difference in the reciprocating movement speed of the driven body 2 due to the influence of gravity. It is desirable to adjust.

  In the present embodiment, the case where the preload member 1 is a coil spring is illustrated, but the preload member 1 may be a leaf spring. Further, the support elastic member 7 may have a function of the preload member 1. That is, the preload member 1 and the supporting elastic member 7 can be configured by a single leaf spring. Specifically, the leaf springs (preload member 1, support elastic member 7) can be urged in the direction in which the driven body 2 is moved in the movement direction (z direction) and in contact with the friction member 3. In addition, it can be realized by attaching to the housing 6 so as to be rotatable. By adopting this configuration, the coil spring can be eliminated, so that the configuration of the preload member can be simplified and the force applied to the driven body 2 can be adjusted by adjusting the amount of rotation of the leaf spring. Therefore, it is possible to provide a driving device with higher mass productivity.

[Embodiment 4]
FIG. 8 is a schematic plan view showing the configuration of the drive device according to Embodiment 4, and FIG. 9 is a schematic side view showing the configuration of the drive device.

  In the following description, the moving direction of the driven body is the z direction, the length direction of the electromechanical transducer element in the stationary state is perpendicular to the z direction, and the direction perpendicular to the z direction and the x direction is the x direction. The y direction is assumed.

  FIG. 9A shows a state where the driven body 2 is at the bottom dead center of the driving stroke, and FIG. 9B shows a state where the driven body 2 is at the top dead center of the driving stroke.

  The drive device in the present embodiment includes a plurality of preload members. That is, the drive device according to the present embodiment includes two coil springs (preload members) 1a and 1b, and the coil springs 1a and 1b are arranged in the moving direction (z direction) of the driven body 2. Have. Therefore, the preload can be stabilized as compared with the case where there is one coil spring. Moreover, the moving stroke of the driven body 2 can be lengthened.

  Since the other configuration of the drive device in the present embodiment is the same as the configuration of the drive device in the first embodiment, the description thereof is omitted.

  The coil springs 1a and 1b are arranged at arbitrary positions in the movement stroke of the driven body 2 so that the central axis directions (length directions) of the coil springs 1a and 1b are not parallel to each other and not on the preload perpendicular line. It is more preferable that the end of the coil spring fixed to the drive body 2 is tilted. Thereby, the fluctuation | variation of the load by the coil springs 1a and 1b and the fluctuation | variation of the force with respect to the moving direction of the to-be-driven body 2 can be relieved. That is, since the extreme value of the resistance force by the coil springs 1a and 1b does not overlap with the movement operation of the driven body 2, the movement operation of the driven body 2 can be performed more stably.

[Embodiment 5]
FIG. 10 is a schematic plan view showing the configuration of the drive device according to the fifth embodiment, and FIG. 11 is a schematic perspective view showing the configuration of the drive device.

  In the following description, the moving direction of the driven body is the z direction, the length direction of the electromechanical transducer element in the stationary state is perpendicular to the z direction, and the direction perpendicular to the x direction and the z direction is the x direction. The y direction is assumed.

  As shown in FIGS. 10 and 11, the drive device in the present embodiment includes a preload member 21 made of a tension coil spring instead of the preload member 1 in the second embodiment. One end of the electromechanical transducer 5 is fixed to the guide member 6 a of the housing 6.

  The preload member 21 includes an effective spring portion 21a having elasticity at the center, and a tightly wound portion (having a diameter smaller than the diameter of the effective spring portion 21a) at both ends of the effective spring portion 21a. The first end portion 21b and 21b are provided, and the end portion (outer side) is further provided with a tightly wound portion (second end portion) 21c and 21c having a diameter similar to the diameter of the effective spring portion 21a. Yes. The diameter of the tightly wound portions 21c and 21c may be larger than the diameter of the tightly wound portions 21b and 21b and not more than the diameter of the effective spring portion 21a. Moreover, the structure currently formed in the one end part of the effective spring part 21a may be sufficient as the close_contact | adherence winding part 21b and the close_contact | adherence winding part 21c.

  On the other hand, the housing 6 has a spring fixing portion 6b that fixes (holds) one end portion of the preload member 21, and the driven body 2 has a protruding portion (holding) that fixes (holds) the other end portion of the preload member 21. Part) 2b. The spring fixing portion 6b of the housing 6 and the protruding portion 2b of the driven body 2 can be fitted into the tightly wound portions 21b and 21b of the preload member 21, thereby hooking the tightly wound portions 21c and 21c. It is formed in a shape that can be fixed.

  That is, the one end of the preload member 21 is fixed to the protruding portion 2b of the driven body 2 and the other end is fixed to the spring fixing portion 6b of the housing 6, and the tensile force (preload load). Thus, the driven body contact portion (friction contact portion) 2a of the driven body 2 is always urged in the direction in which the driven body 2 comes into contact with the friction member 3. According to said structure, even when the small diameter tension coil spring which cannot form a hook part in both ends is used as the preload member 21, a drive device can be easily assembled with a simple structure. Further, since the driven body 2 has the protruding portion 2b, the space in the driving device can be effectively utilized. That is, the drive device can be further downsized.

  Further, as shown in FIG. 10, the preload member 21 is positioned so that its central axis is located on a straight line perpendicular to the contact portion between the friction member 3 and the driven body contact portion 2 a of the driven body 2. Has been placed.

  Further, the preload member 21 and the friction member 3 are arranged with the driven body contact portion 2a interposed therebetween. For this reason, the driven body contact portion 2 a of the driven body 2 is constantly urged by the preload member 21 in a direction in contact with the friction member 3. Further, as shown in FIGS. 10 and 11, the driven body 2 is provided with a guide hole 2c, and the housing 6 is provided with a guide member 6c that fits into the guide hole 2c. Therefore, the driven body 2 is guided by the guide member 6c by the frictional force acting between the friction member 3 and smoothly moves in the z direction. And if the to-be-driven body 2 moves, the preload member 21 will also move together and it will deform | transform.

  In the present embodiment, since a tension coil spring having excellent elasticity is used as the preload member 21, a more stable preload effect can be achieved in the movement process of the driven body 2. Further, it is possible to reduce the load in the direction in which the driven body 2 is driven, and stable driving is possible.

  FIG. 12 is a schematic perspective view showing the configuration of the drive mechanism of the drive device. The drive mechanism includes the friction member 3, the fixed member 4, and the electromechanical conversion element 5, and the friction member 3 and the fixed member 4 configure a drive direction conversion member.

  Since the other configuration of the drive device in the present embodiment is the same as the configuration of the drive device in the first and second embodiments, description thereof is omitted.

  According to said structure, the electromechanical conversion element 5 can be bent by electrical control, and the to-be-driven body 2 can be moved to a fixed direction via the friction member 3. FIG. Further, one end portion (close contact winding portion 21 c) of the preload member 21 is fixed to the protruding portion 2 b of the driven body 2, and the other end portion (close contact winding portion 21 c) is fixed to the spring fixing portion 6 b of the housing 6. Therefore, the preload member 21 is displaced when the driven body 2 moves. Thereby, the structure of the drive device can be simplified and the function can be further stabilized.

[Embodiment 6]
FIG. 13 is a schematic plan view showing the configuration of the drive device in the sixth embodiment.

  As shown in FIG. 13, the drive device according to the present embodiment includes a preload member 31 formed of a torsion coil spring instead of the preload member 21 according to the fifth embodiment. The preload member 31 is a torsion coil spring having a fixed arm 31a and a movable arm 31b at both ends of the torsion coil portion. On the other hand, the housing 6 is formed with a pin 6d that fits in the torsion coil portion of the preload member 31 and a spring abutting portion 6e that is fixed (held) by contacting the fixed arm 31a of the preload member 31. .

  That is, the preload member 31 is fixed (held) by the torsion coil portion being fitted to the pin 6d of the housing 6 and the fixed arm 31a coming into contact with the spring abutting portion 6e of the housing 6. The arm 31b is movable in the y direction. Further, the movable arm 11 b of the preload member 31 is always in contact with the protruding portion 2 b of the driven body 2. As a result, the preload member 31 constantly biases the driven body contact portion 2a of the driven body 2 in a direction in which the driven body contact portion 2a comes into contact with the friction member 3.

  The preload member 31 is arranged so that the direction of the preload applied by the preload member 31 is parallel to the direction perpendicular to the contact portion between the friction member 3 and the driven body contact portion 2a of the driven body 2. Has been.

  Since the other configuration of the drive device in the present embodiment is the same as the configuration of the drive device in the fifth embodiment, the description thereof is omitted.

  In the present embodiment, a torsion coil spring having excellent elasticity is used as the preload member 31, so that a more stable preload effect can be achieved in the movement process of the driven body 2. Moreover, since it is not necessary to consider the diameter size of the preload member as compared with the driving device in the fifth embodiment, it is possible to reduce the size of the driving device in the x direction (the length direction of the electromechanical conversion element). It becomes. That is, the drive device can be further downsized.

[Embodiment 7]
FIG. 14 is a schematic plan view showing the configuration of the drive device according to the seventh embodiment, and FIG. 15 is a schematic perspective view showing the configuration of the drive device.

  As shown in FIGS. 14 and 15, the drive device in the present embodiment is provided with a preload member 41 made of a tension coil spring instead of the preload member 21 in the fifth embodiment. The housing 6 has a spring fixing portion 6 f that fixes (holds) one end of the preload member 41, and the driven body 2 fixes (holds) the other end of the preload member 41. Holding part) 2d. That is, one end of the preload member 41 is fixed to the spring fixing portion 6 f of the housing 6 and the other end is fixed to the spring fixing portion 2 d of the driven body 2.

  Further, the driven body contact portion 2e of the driven body 2 is provided so as to straddle the friction member 3 integrally with the spring fixing portion 2d. That is, the driven body contact portion (friction contact portion) 2e and the spring fixing portion 2d of the driven body 2 are formed so as to sandwich the friction member 3, and the driven body contact portion 2e is connected to the spring fixing portion 2d. The friction member 3 is brought into contact with the opposing surface side. The preload member 41 is always urged by the tensile force (preload load) in the direction in which the driven body contact portion 2e of the driven body 2 comes into contact with the friction member 3.

  Further, the preload member 41 is arranged so that its central axis is located on a straight line perpendicular to the contact portion between the friction member 3 and the driven body contact portion 2 e of the driven body 2.

  Since the other configuration of the drive device in the present embodiment is the same as the configuration of the drive device in the fifth embodiment, the description thereof is omitted.

According to the above configuration, it is possible to provide the driven body 2 with an operation position where the frictional force by the friction member 3 is applied and an operation position where the tensile force (preloading load) is applied by the preloading member 41 close to each other. It becomes. Therefore, the drive of the driven body 2 can be stabilized.
[Embodiment 8]
First, prior to describing the driving apparatus according to the eighth embodiment, the principle of movement of the driven body in the driving apparatus according to the present invention and the drive control means provided in the driving apparatus will be described with reference to FIGS. explain.

  16 and 17 are a side view and a graph for explaining the principle of movement of the driven body in the driving apparatus according to the present invention. FIG. 16 is a schematic side view of the positional displacement of the tip portion of the friction member 3 that is moved by the bending displacement of the electromechanical transducer 5 as observed from the x direction. FIGS. 16A, 16B, and 16C are stationary positions where the electromechanical conversion element 5 is not bent and displaced when the electromechanical conversion element 5 is bent and displaced in a direction approaching the driven body contact portion 2a. The electromechanical conversion element 5 is bent and displaced in a direction away from the driven body contact portion 2a.

  The friction member 3 is bonded and fixed to the fixing member 4 by an adhesive member 43. The elastic fixing member 4 is fixed to the electromechanical transducer 5, and the tip of the friction member 3 is connected to the driven body contact portion 2a. It comes to contact. The contact location and contact area between the friction member 3 and the driven body contact portion 2a can be arbitrarily changed by devising the shape, material, etc. of the friction member 3, but in the following description, For convenience, the case where the friction member 3 is a spherical body and the cross section thereof is a circle as shown in FIG. 16 is taken as an example.

When the friction member 3 is a spherical body, the friction member 3 theoretically comes into contact with the driven body contact portion 2a at a certain point. Here, the electro-mechanical conversion element 5 as a point P ₀ of the contact point between the friction member 3 and the driven member contact portion 2a when in rest position does not bending displacement (FIG. 16 (b)). When the electromechanical conversion element 5 is bent and displaced, the relative positional relationship between the friction member 3 and the driven body contact portion 2a also changes. Hereinafter, the principle of movement of the driven body 2 will be described.

  Since one end of the fixing member 4 is fixed to the electromechanical transducer 5, resonance (primary resonance) occurs in the fixing member 4 due to bending displacement of the electromechanical transducer 5 (primary resonance mode). In the primary resonance, the fixing member 4 swings in the y direction with the fixing portion between the fixing member 4 and the electromechanical conversion element 5 as a substantial center and the other end (tip) of the fixing member 4 as a free end. For example, when a continuous rectangular wave voltage that changes at the same frequency as the primary resonance frequency at which the fixing member 4 causes primary resonance is applied to the electromechanical transducer 5, the free end of the electromechanical transducer 5 is bent in the y direction. In addition to displacement, the tip of the fixing member 4 also vibrates in the y direction due to the primary resonance.

  Here, when the free end of the electromechanical conversion element 5 is displaced in the direction approaching the driven body 2 (+ y direction), the case where the tip of the fixing member 4 swings in the direction approaching the driven body 2 is also in phase. The case where the tip of the fixing member 4 swings in the direction opposite to the displacement direction of the free end of the electromechanical transducer 5, that is, in the direction away from the driven body 2 (−y direction) is reversed (180 °). Phase shift).

  FIG. 16 shows a state where the tip of the fixing member 4 and the free end of the electromechanical transducer 5 are swung in opposite phases. In this case, the displacement (phase shift) of the tip of the fixing member 4 with respect to the displacement of the free end of the electromechanical conversion element 5 varies depending on the preload state of the friction member 3 with respect to the driven member contact portion 2a. The transfer efficiency of 2 is highest in the case of in-phase or reverse phase. That is, the preload of the friction member 3 with respect to the driven body contact portion 2a is adjusted so that the distal end of the fixing member 4 and the free end of the electromechanical transducer 5 swing in the above-described in-phase or reverse phase. The body 2 can be moved most efficiently along the z direction. The phase shift may be either in-phase or reversed-phase, but the moving direction of the driven body 2 is reversed between the in-phase and the reversed-phase. For this reason, in order to change the moving direction of the driven body 2, the polarity of the voltage applied to the electromechanical transducer 5 may be reversed. Hereinafter, the principle of movement of the driven body 2 will be described by taking as an example a state in which the tip of the fixing member 4 and the free end of the electromechanical transducer 5 swing in opposite phases.

For example, when the electromechanical conversion element 5 is bent and displaced in a direction approaching the driven body contact portion 2a, the elastic fixing member 4 bends in a direction away from the driven body contact portion 2a due to the stress of the driven body contact portion 2a. The tip of the friction member 3 fixed to the fixed member 4 slips and moves on the surface (contact surface) of the driven member contact portion 2a from the close-up position to the infinity position. To do. Thereby, the contact point moves from the point P ₀ to the point P ₁ (FIG. 16A).

On the other hand, when the electromechanical conversion element 5 is bent and displaced in a direction away from the driven body contact portion 2a, an acceleration difference is generated between the elastic fixing member 4 and the electromechanical conversion element 5 having substantially no elasticity. The fixed member 4 bends in the direction approaching the driven body contact portion 2a, and the tip of the friction member 3 fixed to the fixed member 4 causes the surface (contact surface) of the driven body contact portion 2a to move in the z direction, that is, Slip and move from the infinity position to the close-up position. As a result, the contact point moves from the point P ₁ to the point P ₂ via the point P ₀ (FIG. 16C).

That is, according to the bending displacement of the electromechanical conversion element 5, the friction member 3 is in contact with the driven body contact portion 2a at different contact points. Therefore, when the electromechanical transducer 5 is repeatedly bent and displaced, the tip of the friction member 3 repeatedly moves the position shown in FIG. 16 (point P ₁ → point P ₀ → point P ₂ → point P ₀ → point P ₁ ) It will be done. For this reason, it is possible to recognize the positional displacement of the tip portion of the friction member 3 based on the relative distance between these contact points (points P ₀ , P ₁ , P ₂ ) in the z direction.

FIGS. 17A and 17B are graphs for explaining the principle of movement of the driven body in the driving apparatus of the present invention, and are graphs showing the relationship between the time required for bending displacement and the position displacement of the contact point. is there. In the graph, the curve k represents the position of the tip portion of the friction member 3, whereby the position of the contact point of the tip portion when the time t elapses from the time when the bending displacement is started can be specified. it can. However, although the point P ₀ indicates that the tip of the friction member 3 is at the stationary position, the axis representing the time t on the graph is not necessarily the center axis of the curve k. That is, the point P ₁ and the point P ₂ are located at the peak of the curve k, respectively, but the distance from the point P ₁ to the point P ₀ that is perpendicular to the axis representing the time t, and the point P distance from ₂ to the point P _0, i.e., displacement distance from point P ₀ is a rest position to the point P ₁ and point P ₂ is not necessarily equal.

The electromechanical transducer 5 is repeatedly bent and displaced, and the position of the tip of the friction member 3 is repeatedly displaced in the order of point P ₁ → point P ₀ → point P ₂ → point P ₀ → point P _1. 2 can be displaced repeatedly in the z direction. That is, the driven body 2 can be moved in the z direction. FIG. 17A is a graph showing a case where the driven body 2 is moved in the z direction, that is, from the position at infinity to the close-up position, and the tip of the friction member 3 is point P ₁ → The driven body 2 can be moved by being relatively slow when the point P ₀ → the point P ₂ is moved, and relatively fast when the point P ₂ → the point P ₀ → the point P _{1 being} the return path. .

On the other hand, the electromechanical transducer 5 is repeatedly bent and displaced, and the tip of the friction member 3 is repeatedly displaced in the order of point P ₂ → point P ₀ → point P ₁ → point P ₀ → point P _2. The driving body 2 can be repeatedly displaced in the -z direction. That is, the driven body 2 can be moved in the −z direction. FIG. 17B is a graph showing a case where the driven body 2 is moved in the −z direction, that is, in the direction from the close-up position to the infinity position, and the tip portion of the friction member 3 is the point P ₂ that is the forward path. It is possible to move the driven body 2 by moving relatively slowly when moving from the point P ₀ → point P ₁ and relatively fast when moving from the point P ₁ → point P ₀ → point P ₂ which is the return path. it can.

By changing the amount and speed of the bending displacement of the electromechanical transducer 5, as is apparent from FIGS. 17A and 17B, at the points P ₁ and P ₂ , the tip of the friction member 3 is changed. The direction of displacement is reversed and the acceleration is also changed. Thereby, the driven body 2 can be moved in the −z direction and the z direction.

  In this way, by changing the amount and speed of the bending displacement of the electromechanical conversion element 5 to generate different accelerations in the forward path and the return path, the difference in acceleration between the electromechanical conversion element 5 and the fixed member 4 is obtained. Therefore, the difference between the time for the tip of the friction member 3 to slip on the contact surface with the driven body contact portion 2a and the time for sticking can be given. Therefore, the travel distance of the driven body 2 can be made different between the forward path and the return path, and as a result, the driven body 2 can be moved in the −z direction or the z direction.

More specifically, in the graph of FIG. 17A, since the acceleration is relatively small when moving from the point P ₁ → the point P ₀ → the point P ₂ which is the forward path, the electromechanical transducer 5 generated in unit time. The phase lag (phase difference) of the fixing member 4 with respect to is relatively small, and the tip of the friction member 3 can slip a relatively long distance. On the other hand, since the acceleration is relatively large when moving from the point P ₂ → the point P ₀ → the point P ₁ , which is the return path, the phase delay (phase difference) of the fixing member 4 with respect to the electromechanical transducer 5 generated per unit time is also relatively large. Large, the tip of the friction member 3 cannot slip a long distance. That is, since the frictional action of the tip of the friction member 3 with respect to the driven body contact portion 2a continues for a relatively long time in the forward path, the driven body 2 is moved from the infinity position toward the close-up position. Can do.

On the other hand, in the graph of FIG. 17 (b), the acceleration is relatively small when the forward point P ₂ → the point P ₀ → the point P ₁ is moved, and the backward point P ₁ → the point P ₀ → the point P _2. Since the acceleration is relatively large during the movement, the driven body 2 can be moved from the close-up position to the infinity position based on the same principle as described above.

  In the above, the movement principle which moves the to-be-driven body 2 by utilizing the phase delay (phase difference) of the fixing member 4 with respect to the electromechanical transducer 5 has been described. However, even in a frequency band where the phase lag does not occur (the amount and speed of bending displacement), the operation described in FIGS. 16A and 16B is repeated to cause a difference in acceleration between the forward path and the return path. Therefore, the driven body 2 can be moved in a desired moving direction.

  As a simple method of changing the amount and speed of bending displacement of the electromechanical transducer 5 and giving different accelerations in the forward path and the backward path, a pulsed voltage is repeatedly applied between the electrodes provided in the electromechanical transducer 5. A method is mentioned. In this method, the pulse duty (interval) and frequency are set appropriately, and the amount and speed of the bending displacement of the electromechanical transducer 5 are changed by the action of the transfer function of the vibration system. Further, the moving direction of the driven body 2 can be changed by inverting the pulse voltage applied between the electrodes provided in the electromechanical transducer 5.

  FIG. 18 is a block diagram showing an example of drive control means for controlling the electromechanical transducer 5 based on the moving principle. That is, the drive device according to the present invention further includes drive control means for outputting a pulsed voltage (drive signal) to the electromechanical transducer 5.

  As shown in FIG. 18, the drive control means includes a controller 10, a pulse generator 11, an exclusive OR gate 12, an inverter gate 13, an AND gate 14, switch elements 15a to 15d, and the like. The inverter gate 13, the AND gate 14, and the switch elements 15a to 15d constitute an H bridge circuit. When the signal S output from the exclusive OR gate 12 is at a low level, the switch element 15a and the switch element 15d are closed. When the signal S is at a high level, the switch element 15b and the switch element 15c are closed. Therefore, when the signal S is at a low level, a voltage of + V [V] is applied between the electrode α provided on the electromechanical transducer 5 and the electrodes β1 and β2, and when the signal S is at a high level. The voltage of −V [V] is applied between the electrode α and the electrodes β1 and β2.

  The electromechanical conversion element 5 is, for example, a bimorph type piezoelectric element, and when a voltage of + V [V] is applied between the electrode α and the electrodes β1 and β2 in a state where one end is fixed, FIG. As shown in the figure, when a voltage of −V [V] is applied between the electrode α and the electrodes β1 and β2, it is bent and displaced in the opposite direction. That is, the bending direction of the electromechanical transducer 5 can be controlled depending on whether the signal S (driving signal), which is a pulse voltage applied between the electrode α and the electrodes β1 and β2, is low level or high level. Therefore, the drive control means can control the amount and speed of the bending displacement of the electromechanical transducer 5 by appropriately setting the duty and frequency of the pulse as the signal S.

  The controller 10 outputs an EN signal, a DIR signal, and DF data. The controller 10 is preferably a programmable controller composed of peripheral devices such as a microcomputer and a memory. As shown in FIG. 18, the EN signal is output to the AND gate 14. For this reason, when the EN signal is at a high level, the driving of the electromechanical conversion element 5 is started, and when the EN signal is at a low level, all the switch elements 15a to 15d are opened and the driving of the electromechanical conversion element 5 is stopped. Is done. That is, the EN signal is a signal that controls the driving and stopping of the electromechanical transducer 5.

  The pulse generator 11 generates a pulse-shaped signal having a duty and frequency specified in advance based on the DF data input from the controller 10, and outputs the pulse-shaped signal to the exclusive OR gate 12. That is, the DF data is data for controlling the amount and speed of the bending displacement of the electromechanical transducer 5.

  As shown in FIG. 18, the DIR signal is output to the exclusive OR gate 12. Therefore, when the DIR signal is at a low level, the phase of the DIR signal and the pulsed signal input from the pulse generator 11 are the same. When the DIR signal is at a high level, the DIR signal And the phase of the pulse signal are reversed. That is, the DIR signal is a signal that controls the driving direction of the electromechanical transducer 5.

  Therefore, by appropriately adjusting the EN signal and the DIR signal, the driving and stopping of the electromechanical conversion element 5 and the driving direction can be controlled. Further, by appropriately changing the DF data, it is possible to control the amount and speed of the bending displacement of the electromechanical transducer 5 suitable for the direction in which the driven body 2 is moved.

  Next, a driving apparatus according to the eighth embodiment will be described below with reference to FIG. FIG. 19 is a graph for explaining a method of controlling the movement distance of the driven body 2 performed by the drive control means included in the drive device.

  In the drive devices according to Embodiments 1 to 7 described above, for example, as shown in FIG. 2B, the spring center axis of the preload member 1 is inclined with respect to the preload perpendicular as the driven body 2 moves. A preload component force is generated in the moving direction of the driven body 2. Since this preload component force becomes a load with respect to the driving force generated by the frictional contact between the driven body 2 and the friction member 3, the positional displacement of the driven body 2 is affected. That is, with the displacement of the driven body 2 that moves due to the bending displacement of the electromechanical conversion element 5, a load due to the preload component force is generated in the moving direction of the driven body 2. The stroke (displacement) amount of the driven body 2 in consideration of the load increase / decrease amount due to the preload component force can be estimated by the following equation 1.

However, n: number of steps x _i : stroke (displacement) amount of _i- th step K: pre-pressure by pre-load member F: driving force generated by frictional contact between driven body and friction member (= α × μ × K)
μ: Friction coefficient between driven body and friction member (approximately 0.1 to 0.3)
α: Transmission ratio of frictional force at contact point between driven body and friction member (0 to 1.0)
M: Mass of driven body (driven body 2 including driven body contact portion 2a) θ (x _n ): Angle formed by spring center axis and preload perpendicular Td: Driving time Here, driven body 2 is equal to one. One step is to rotate the position (unit control movement). For example, K = 7 g, F = 0.92 gf (μ = 0.15 (experimental value), α = 0.65 (experimental value)), M = 0.12 g, θ (x _n ) = ± 5. In the case of 35 deg and Td = 600 μsec, the number of steps and the stroke amount have a relationship as shown in the graph of FIG. As is apparent from the graph, the stroke amount (unit control movement amount) per step tends to gradually decrease with the displacement of the driven body 2, that is, the linearity (Δx as the number of steps increases. ) Is declining. The linearity refers to the amount of movement of the driven body 2 by the frictional contact between the driven body 2 and the friction member 3 per step. Therefore, by keeping the linearity constant, the moving distance of the driven body 2 per step can be kept constant.

  As shown in FIG. 19 (a), when the stroke amount per step gradually decreases, the decrease in linearity is corrected by adjusting the signal S (drive signal) according to the number of steps (improvement). Is possible). Specifically, for example, there is a method of increasing the number of pulses of the signal S (number of drive pulses).

For example, when the movement amount X of the driven body 2 per step is 12 μm and the positional displacement of the driven body 2 is set to 0.6 mm (moving from 0 (close-up position) to 0.6 mm), the stroke amount In order to keep the linearity of the above constant, Δx _n = Δx _{n + 1} = X (12 μm) in the above equation 1. Therefore, the following formula 2 can be obtained by modifying the formula 1.

  Further, when Expression 2 is modified, the following Expression 3 is obtained.

  FIG. 19B is a graph (correction table) showing the relationship between the number of steps obtained based on Equation 3 above, the drive time, and the number of pulses of the signal S (number of drive pulses). According to this correction table, the linearity of the stroke amount can be kept constant by adjusting the driving time and the number of driving pulses to values predetermined for each step. FIG. 19C shows a control state in which the amount of movement of the driven body 2 per step is constant when the linearity is constant.

  Therefore, the drive device according to the present embodiment can be driven by the displacement of the driven body 2 that moves due to the bending displacement of the electromechanical transducer 5 so that the control method described above can be performed. Drive control means for outputting a signal S (drive signal) determined in advance by a correction table to the electromechanical transducer 5 according to the amount of increase or decrease of the load generated in the direction of movement 2.

  The method for keeping the linearity constant is not limited to the above control method for adjusting the number of drive pulses, for example, a control method for changing the duty per step of the pulse that is the signal S, or the frequency per step of the pulse. There is a control method to change. Also in the control method for changing the duty and frequency of the pulse, it is preferable to use a graph (correction table) as shown in FIG. For example, a duty correction table or a frequency correction table can be used. Adjustment of the signal S (drive signal) for each step can be easily performed by previously programming the controller 10 of the drive control means described above.

  However, in the control method of changing the duty and frequency of the pulse, depending on the value of the duty and frequency, either the forward path or the return path cannot be controlled, or the drive control means is based on the electrical resonance with the electromechanical transducer 5 There is a possibility that the power consumption of the battery increases rapidly. Accordingly, a control method for adjusting the number of drive pulses is more preferable as a control method performed by the drive control means. The control method for adjusting the number of drive pulses does not cause the above-described fear.

  When the driving device according to the present invention is used for driving a lens of an imaging device such as a camera, for example, to provide a smaller product with a more uniform driving speed and better focus adjustment accuracy. Can do.

DESCRIPTION OF SYMBOLS 1 Preload member 2 Driven body 2a Driven body contact part 2b Protrusion part 2c Guide hole 2d Spring fixing part 2e Driven body contact part 3 Friction member 4 Fixing member 5 Electromechanical transducer 6 Housing 6a Guide member 6b Spring fixing part 6c Guide member 6d Pin 6e Spring contact portion 6f Spring fixing portion 7 Support elastic member 10 Controller 11 Pulse generator 12 Exclusive OR gate 13 Inverter gate 14 And gates 15a to 15d Switch element 21 Preload member 21a Effective spring portion 21b Adhesive winding Portion 21c tightly wound portion 31 preload member 31a fixed arm 31b movable arm 41 preload member

Claims (10)

An electromechanical conversion element having one end fixed to the housing and causing bending displacement by electrical control;
A friction member having one end connected to the electromechanical transducer and the other end in frictional contact with the driven body;
One end is held by the driven body and the other end is held by the housing, and includes a preload member that biases the driven body in a direction of frictional contact with the friction member,
The preload member is a tension coil spring;
The driven body has a friction contact portion that frictionally contacts the friction member, and a holding portion that holds one end of the preload member,
The preload member is located between the friction contact portion and the holding portion ,
The tension coil spring includes an effective spring portion at a central portion thereof, a first end portion having a diameter smaller than the diameter of the effective spring portion at one end or both ends of the effective spring portion, and further outside thereof. A second end having a diameter greater than the diameter of the first end;
A drive device characterized in that a first end portion is fitted into at least one of the driven body and the casing and the second end portion is hooked and held . An electromechanical conversion element having one end fixed to the housing and causing bending displacement by electrical control;
A friction member having one end connected to the electromechanical transducer and the other end in frictional contact with the driven body;
One end is held by the driven body and the other end is held by the housing, and includes a preload member that biases the driven body in a direction of frictional contact with the friction member,
The preload member is a tension coil spring;
The driven body has a friction contact portion that frictionally contacts the friction member, and a holding portion that holds one end of the preload member,
The drive device characterized in that the friction member is located between the friction contact portion and the holding portion. The tension coil spring includes an effective spring portion at a central portion thereof, a first end portion having a diameter smaller than the diameter of the effective spring portion at one end or both ends of the effective spring portion, and further outside thereof. A second end having a diameter greater than the diameter of the first end;
The driving device according to claim 2 , wherein a first end portion is fitted into at least one of the driven body and the casing and the second end portion is hooked and held. The drive device according to claim 1 or 3, wherein the first end portion and the second end portion are tightly wound with no elasticity.   5. The drive device according to claim 1, wherein a fixing member is provided between the electromechanical conversion element and the friction member. 6.   6. The driving apparatus according to claim 5, wherein the fixing member is configured to make the moving direction of the friction member different from the driving direction of the electromechanical conversion element.   In accordance with the displacement of the driven body that moves due to the bending displacement of the electromechanical conversion element, a predetermined drive signal is converted into the electromechanical conversion according to the amount of increase or decrease in the load that occurs in the moving direction of the driven body. The drive apparatus according to claim 1, further comprising drive control means for outputting to the element.   The drive device according to claim 7, wherein the drive signal is a pulse-like drive signal.   An imaging apparatus comprising the drive device according to claim 1.   An electronic apparatus comprising the drive device according to claim 1 or the imaging device according to claim 9.

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