JP2010063349A - Driving device, image sensing device with the same, and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving device with improved driving stability of a body to be driven. <P>SOLUTION: The driving device 10 includes: a bending displacing member 5 whose one end is fixed and having an excited bending displacement; a frictional member 3 connected at a free end of the bending displacing member 5 on either of surfaces deflected in the bending displacing direction of the bending displacing member 5; and a body to be driven 2 brought into friction-contact with the frictional member 3. Consequently, the driving device 10 brings the frictional member 3 in contact with the body to be driven 2 with a high positional accuracy because the position of the frictional member 3 is not affected by a dimensional tolerance in the longitudinal direction of the bending displacing member 5. Accordingly, the driving stability of the body to be driven 2 can be improved. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  In recent years, a drive device using an electromechanical conversion element (piezoelectric element) has been proposed as a drive device for driving a driven body. Such a driving device is often used as a driving device that drives a lens of an optical device such as a camera.

  Patent Documents 1 and 2 disclose a driving device using a piezoelectric element that bends and displaces. The driving devices disclosed in Patent Documents 1 and 2 include a piezoelectric element, a friction member (sliding member) formed at a free end of the piezoelectric element, a preload mechanism for biasing the piezoelectric element, a driven body, It has. The friction member and the driven body are in frictional contact by the preload of the preload mechanism, and when the piezoelectric element is bent and displaced by voltage application, the driven body slides due to the frictional force between the friction member and the driven member.

JP 2007-252103 A (published September 27, 2007) JP 2007-274790 A (released on October 18, 2007)

  However, in the driving devices disclosed in Patent Documents 1 and 2, the friction member is disposed at the longitudinal end portion of the piezoelectric element, and the preload direction of the preload mechanism is the same as the longitudinal direction of the piezoelectric element. The positional accuracy of the friction member is easily influenced by the dimensional tolerance in the longitudinal direction of the piezoelectric element. The longitudinal direction of the piezoelectric element is a direction having a particularly large dimensional tolerance. If the position of the friction member in the preload direction shifts due to the dimensional tolerance of the piezoelectric element in the longitudinal direction, the reproducibility of the contact state between the driven body and the friction member becomes worse, and the preload state on the driven body becomes unstable. . In Patent Documents 1 and 2, since the driven body is driven by the friction drive system, if the preload state with respect to the driven body is unstable, the driven body cannot be stably driven. The position reproducibility of the driven body is reduced.

  In addition, in the driving devices disclosed in Patent Documents 1 and 2, the frictional portion is worn by operating for a long period of time, so that the contact state between the driven body and the frictional member is changed, or the frictional portion is scratched. Thus, there is a problem that the position reproducibility of the driven body is lowered.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a drive device in which the drive stability of the driven body is improved by increasing the positional accuracy of the friction member. It is another object of the present invention to provide a drive device that reduces fluctuations in drive characteristics due to aging of friction members and realizes long-term drive stability.

  In order to solve the above-described problem, the drive device according to the present invention is a drive device that drives a driven body, the bending displacement member having one end fixed and bending displacement excited, and the bending displacement member In any one of the surfaces bent in the bending displacement direction, a friction member connected to the free end of the bending displacement member and in frictional contact with the driven body is provided.

  In the above configuration, when the bending displacement member is bent and displaced, the friction member connected to the free end of the bending displacement member is displaced together with the bending displacement member. The displacement of the friction member is transmitted to the driven body that is in frictional contact with the friction member. As a result, the driven body is driven.

  The direction from the fixed end to the free end in the bending displacement member is defined as the longitudinal direction. At this time, the surface of the bending displacement member that is connected to the friction portion and is bent in the bending displacement direction is substantially parallel to the longitudinal direction. For this reason, the position of the friction member in the longitudinal direction of the bending displacement member is not affected by the dimensional tolerance in the longitudinal direction of the bending displacement member.

  Since the bending displacement member has the largest dimensional tolerance in the longitudinal direction, according to the above configuration, the positional accuracy of the friction member can be improved. This improves the accuracy of the displacement transmitted to the driven body by the friction member, so that the driven body can be driven stably.

  Furthermore, in the drive device according to the present invention, one end of the bending displacement member that is fixed is fixed to one of the surfaces of the bending displacement member that bends in the bending displacement direction. When the fixed surface is a fixed surface, the friction member is preferably provided on the same plane as the fixed surface in the bending displacement member.

  In the above configuration, the surface on which the friction member is provided is on the same surface as the fixed surface of the bending displacement member. According to this configuration, when the direction perpendicular to the surface of the bending displacement member that is bent in the bending displacement direction is the thickness direction of the bending displacement member, the positional accuracy of the friction member depends on the dimensional tolerance of the thickness of the bending displacement member. Not affected. Therefore, the said structure can improve the positional accuracy of a friction member more.

  The drive device according to the present invention includes an intermediate member that is provided at a free end of the bending displacement member and is bent and displaced in a direction different from the bending displacement member, and the friction member is a free end of the intermediate member. It is preferable that the connection between the friction member and the free end of the bending displacement member is performed via the intermediate member.

  In the above configuration, when the bending displacement member is bent, the intermediate member is bent and displaced in a direction different from that of the bending displacement member along with the bending displacement of the bending displacement member. The friction member fixed to the free end of the intermediate member is displaced together with the intermediate member in a direction different from that of the bending displacement member. Since the displacement of the friction member is transmitted to the driven body that is in frictional contact with the friction member, the driving device according to the present invention can drive the driven body in a direction different from the longitudinal direction of the bending displacement member. it can.

  Furthermore, in the drive device according to the present invention, one end of the bending displacement member that is fixed is fixed to one of the surfaces of the bending displacement member that bends in the bending displacement direction. When the fixed surface is a fixed surface, the surface of the intermediate member on which the friction member is provided is preferably on the same plane as the fixed surface.

  In the above configuration, the surface on which the friction member is provided in the intermediate member is on the same plane as the fixed surface of the bending displacement member. For this reason, the positional accuracy of the friction member in the thickness direction of the bending displacement member is not affected by the dimensional tolerance of the thickness of the bending displacement member. Therefore, the positional accuracy of the friction member can be further improved.

  In the driving device according to the present invention, the bending displacement member is formed of a displacement member whose shape displacement is excited by applying a voltage, and a shim member stacked on the displacement member. It is preferable that the member has a shim extending portion extended to the free end side of the bending displacement member, and the friction member is provided in the shim extending portion.

  According to the above configuration, since the bending displacement member is formed of the displacement member and the shim member laminated on the displacement member, the thickness tolerance of the bending displacement member formed by the lamination process increases. . Here, since the friction member is provided in the shim extension portion, the positional accuracy of the friction member in the thickness direction of the bending displacement member only needs to consider the dimension crossing of the thickness of the displacement member. Therefore, even if the friction member is provided on another surface that is not the same plane as the fixed surface of the bending displacement member, the positional accuracy of the friction member can be improved.

  Furthermore, in the drive device according to the present invention, it is preferable that the fixed end of the bending displacement member is on the shim member.

  According to the above configuration, the surface on which the friction member is provided and the fixed end of the bending displacement member are on the same shim member. For this reason, the positional accuracy of the friction member in the thickness direction of the bending displacement member only needs to consider the dimensional tolerance of the thickness of the shim member. Therefore, even if the friction member is provided on another surface that is not the same plane as the fixed surface of the bending displacement member, the positional accuracy of the friction member can be improved.

  Furthermore, in the drive device according to the present invention, it is preferable that the shim extension portion has a notch, and the shim extension portion is bent and displaced in a direction different from the free end of the bending displacement member. .

  According to the above configuration, the drive device according to the present invention can be configured such that the driven body is moved in the longitudinal direction of the bending displacement member, similarly to the case where the intermediate member is used, without using the intermediate member that is separate from the bending displacement member. Can be driven in different directions.

  In the driving device according to the present invention, a plane substantially parallel to the bending displacement direction of the intermediate member or the shim extending portion is orthogonal to a plane substantially parallel to the bending displacement direction of the bending displacement member. It is preferable.

  According to the above configuration, the bending member and the driven body are arranged such that the thickness direction of the bending displacement member is perpendicular to the moving direction of the driven body. According to this arrangement, it becomes easy to reduce the size of the drive device according to the present invention in a direction substantially perpendicular to the moving direction of the driven body.

  In the driving apparatus according to the present invention, it is preferable that the friction member is in direct contact with the driven body.

  According to the above configuration, the driving apparatus according to the present invention does not need to use an intermediate driven body in order to drive the driven body. This facilitates downsizing the drive device according to the present invention.

  In the drive device according to the present invention, the moving direction of the driven body and the surface of the bending displacement member that bends in the bending displacement direction may be substantially parallel.

  In addition, the drive device according to the present invention includes a fixing portion disposed between the driven body and the bending displacement member, and one end of the bending displacement member fixed is fixed to the fixing portion. It is preferable.

  According to the above configuration, since the one end of the bending displacement member is fixed to the fixed portion, the bending displacement member can stabilize the displacement characteristics when the bending displacement is performed. Further, since the fixing portion is disposed between the driven body and the bending displacement member, the workability when fixing the bending displacement member to the fixing portion can be improved, and as a result, the production of the driving device according to the present invention can be improved. Can be improved.

  The drive device according to the present invention preferably includes a preload mechanism that urges the driven body toward the friction member.

  According to the above configuration, the driven body is constantly urged against the friction member by the preload member. Thereby, the driven body can maintain a stable position.

  In the driving apparatus according to the present invention, the driven body is provided with a contact member that moves integrally with the driven body and that makes frictional contact with the friction member. One of the members is preferably formed with a film made of a solid lubricating material, and the other is formed of a carbon sintered material. Further, the film made of the solid lubricating material is preferably a diamond-like carbon film.

  According to the above configuration, wear of the contact member and the friction member can be reduced, and generation of scratches can be prevented. As a result, there is little change in drive characteristics even with long-term operation, and the durability of the drive device can be improved. Furthermore, it is possible to provide a driving device that is excellent in drop impact resistance.

  A driving apparatus according to the present invention includes an optical system that forms an image of an object to be imaged, and an image sensor that converts an image formed by the optical system into an electrical signal, and the driven body is the optical system. Can be used as an imaging device.

  In addition, the imaging apparatus according to the present invention includes a drive shaft that supports driving of the driven body, and the shortest distance between the optical axis of the optical system and the drive shaft is determined by the driven member in the friction member. It is preferable that the distance is shorter than the shortest distance between the contact portion with the drive body and the drive shaft.

  According to the above configuration, the tilt of the driven body can be suppressed even when the positional relationship between the friction member and the driven body is shifted due to, for example, an assembly shift at the time of manufacturing the driving device. That is, the shift of the optical center position of the optical system held by the driven body can be reduced. Moreover, since the change in the preload direction urged by the driven body is reduced, the driving characteristics of the driven body can be stabilized.

  In addition, the drive device and the imaging device according to the present invention can be applied to electronic devices.

  According to the drive device of the present invention, the bending displacement of one of the bending displacement member having one end fixed and the bending displacement being excited and the surface of the bending displacement member that bends in the bending displacement direction. Since the friction member connected to the free end of the member and the driven body that is in frictional contact with the friction member are provided, the positional accuracy of the friction member is improved, thereby stabilizing the driving characteristics of the driven body. To do.

(A) is a top view which shows schematically the drive device in the 1st Embodiment of this invention, (b) is the side view. 1 is a perspective view schematically showing a drive device according to a first embodiment of the present invention. It is a perspective view which shows roughly the bending displacement member of the drive device in the 1st Embodiment of this invention. (A) (b) is a top view for demonstrating the position shift of a friction member and a to-be-driven body. It is a perspective view which shows roughly the drive device in the 2nd Embodiment of this invention. It is a perspective view which shows roughly the bending displacement member of the drive device in the 2nd Embodiment of this invention. It is a schematic diagram which shows schematically the drive device in the 3rd Embodiment of this invention. It is a schematic diagram which shows schematically the drive device in the 4th Embodiment of this invention. It is a schematic diagram which shows schematically the drive device in the 5th Embodiment of this invention.

[Embodiment 1]
The first embodiment of the present invention will be described with reference to FIGS. 1 to 4 as follows.

  First, a schematic configuration of the drive device 10 in the present embodiment will be described with reference to FIGS. FIG. 1 (a) is a side view showing the driving device 10, and FIG. 1 (b) is a front view thereof. FIG. 2 is a perspective view showing the driving device 10.

  As shown in FIGS. 1 and 2, the drive device 10 is a drive device that drives the driven body 2 in the Z direction. The driving device 10 includes a bending displacement member 5 in which bending displacement is caused by electrical control, an intermediate member 4 provided with one end on the bending displacement member 5, a friction member 3 provided on the intermediate member 4, and a driven member 2 to be driven. A preload member 1, a guide shaft (drive shaft) 8, and a housing 6 that urge the drive body contact portion 2a toward the friction member 3 are provided.

  Here, the driven body 2 is a member that is moved by the driving device 10. The driven body contact portion 2 a formed in a protruding shape from the driven body 2 and the friction member 3 side of the driven body contact portion 2 a The contact member 2d is formed. The driven body contact portion 2 a and the contact member 2 d are members that are bonded and fixed to the driven body 2 or integrally formed, and move together with the driven body 2. Therefore, the driving apparatus 10 does not require an intermediate driven body for driving the driven body 2. As a result, the drive device 10 can be easily downsized, and the degree of freedom of arrangement of each member can be increased.

  In the following description, as shown in FIG. 1, the direction of movement of the driven body 2 is the Z direction, the longitudinal direction of the bending displacement member 5 in a stationary state, and the direction perpendicular to the Z direction. Is the Y direction, and the direction perpendicular to the Y direction and the Z direction is the X direction.

  The bending displacement member 5 is a member that causes bending displacement by electrical control. In the bending displacement member 5, an end fixed to the housing 6 is referred to as a fixed end, and an end on the opposite side of the fixed end in the Y direction where a bending displacement occurs is referred to as a free end. As shown in FIGS. 1A and 1B, the bending displacement member 5 is disposed so that the bending displacement direction of the free end is substantially perpendicular to the moving direction (Z direction) of the driven body 2. .

  The fixed end of the bending displacement member 5 is bonded and fixed to a fixed wall (fixed portion) 6 a arranged in parallel with the moving direction (Z direction) of the driven body 2 in the housing 6. Note that a portion that is bonded and fixed to the fixed wall 6a at the fixed end of the bending displacement member 5 is defined as a fixed surface 5c. At this time, the fixed surface 5 c of the bending displacement member 5 is a surface orthogonal to the thickness direction of the bending displacement member 5. Note that the thickness direction of the bending displacement member 5 is the X direction, and the plane orthogonal to the thickness direction is the YZ plane.

  The fixed wall 6a does not necessarily have to be integrated with the housing 6, but it is preferable that the fixed wall 6a and the housing 6 are integrated because the number of members can be reduced and the positional accuracy can be improved. The fixed wall 6a is preferably disposed between the bending displacement member 5 and the driven body 2 in the X direction. With such an arrangement, workability when the bending displacement member 5 is attached to the fixed wall 6a is improved, and productivity can be increased.

  Both end portions of the preload member 1 are fixed to the driven body preload portion 2 b of the driven body 2 and the housing preload portion 6 b of the housing 6. Between the preload member 1 and the friction member 3, a driven body contact portion 2a of the driven body 2 and a contact member 2d bonded and fixed to the driven body contact portion 2a are disposed. The preload member 1 is configured to constantly urge the driven body contact portion 2a of the driven body 2 toward the friction member 3 (contact member 2d), and the contact member 2d and the friction member 3 are in frictional contact. With such a configuration, the driven body 2 can maintain a stable position.

  The preload member 1 may be a member having elasticity such as a coil spring. In the case where the preload member 1 is a coil spring, it is preferable that one end or both ends of the preload member 1 be tightly wound with no elasticity. According to this configuration, when the coil spring is fixed to each of the driven body 2 and the housing 6, a large application area of an adhesive or the like can be ensured. Furthermore, variations in the fixing range of the coil spring caused by manufacturing tolerances do not occur, and a stable preload can be realized by the coil spring.

  The guide shaft 8 may be a guide that supports driving of the driven body 2 and smoothly moves the driven body 2 along the Z direction. In the present embodiment, the guide shaft 8 is a shaft provided perpendicular to the bottom surface of the housing 6, and the shaft is passed through a shaft hole provided in the driven body 2. The guide shaft 8 is not limited to a shaft as long as it guides the driven body 2, and may be, for example, a linear guide or a leaf spring.

  The guide shaft 8 has an effect of keeping the position of the driven body 2 stable. For example, when the driving device 10 is applied to a portable electronic device such as a mobile phone, the driven device 2 is prevented from being detached from the housing 6 because the electronic device is highly likely to receive an impact due to dropping or the like. It is desirable to do. Since the guide shaft 8 has the above-described effect, it is useful for preventing the driven body 2 from being detached from the housing 6.

  In order for the driven body 2 to be guided (moved) by the guide shaft 8, the shaft hole diameter of the driven body 2 needs to be larger than the diameter of the guide shaft 8. In order to guide the driven body 2 smoothly, the backlash between the guide shaft 8 and the shaft hole diameter of the driven body 2 (shaft hole diameter of the driven body 2−guide shaft 8 diameter) is, for example, 5 to 15 μm. It is preferable to manage them. By managing the play in this way, it is possible to reduce the occurrence of tilting of the driven body 2 and to drive the driven body 2 smoothly.

  The housing 6 has a frame structure including the preload member 1, the bending displacement member 5, and the like inside. In the present embodiment, the housing 6 is used to ensure the strength and function of the driving device 10, but is not necessary depending on the mounting state of the driving device. For example, the housing 6 is unnecessary when the driving device 10 is built in an electronic device and the electronic device is provided with another structure that can replace the housing 6.

  Next, the drive mechanism in the drive device 10 will be described below with reference to FIG. FIG. 3 is a perspective view showing the bending displacement member 5 and its peripheral members.

  As shown in FIG. 3, the drive mechanism in the drive device 10 is formed of a bending displacement member 5, an intermediate member 4, and a friction member 3.

  As the bending displacement member 5, a bimorph type piezoelectric element is used. Further, as shown in FIG. 3, the bending displacement member 5 is composed of a shim member 5a made of a metal plate and a multilayer piezoelectric element (displacement member) 5b formed on both surfaces of the shim member 5a, which is displaced in shape. . The laminated piezoelectric element 5b may be formed only on one side of the shim member 5a.

  Moreover, since the bending displacement member 5 should just have the bending displacement degree required in order to maintain the normal function which a drive device should have, the bending displacement member 5 is not limited to a specific structure and shape. For example, a shape memory alloy or the like may be used instead of the piezoelectric element.

  An electrode portion (not shown) of the bending displacement member 5 is soldered to the electrode terminal 9 shown in FIG. 1, and the bending displacement member 5 is electrically bent and displaced by an external drive circuit (not shown). Further, one end of the bending displacement member 5 is a fixed end bonded and fixed to the fixed wall 6a of the housing 6, and the other end is a free end.

  A friction member 3 is connected to a free end of the bending displacement member 5 via an intermediate member 4. As shown in FIG. 3, the intermediate member 4 has a plate shape in which a cut 4 a is formed on one side, and the cut 4 a is arranged in parallel with one side on the free end side of the bending displacement member 5. The intermediate member 4 in the present embodiment is not limited as long as it has a free end in the Z direction, and one end of the “L” shape is fixed to one side of the corner at the free end of the bending displacement member 5. It may be a configuration. The friction member 3 is fixed to the free end of the intermediate member 4.

  When a voltage is applied to the bending displacement member 5, the free end of the bending displacement member 5 is bent and displaced in a direction substantially parallel to the XY plane as indicated by an arrow (direction 1) in FIG. On the other hand, when the intermediate member 4 performs a seesaw motion in accordance with the bending movement of the bending displacement member 5, the free end of the intermediate member 4 is in a direction substantially parallel to the XZ plane as shown by an arrow (direction 2) in FIG. Bends and displaces. As a result, the friction member 3 is displaced in a direction substantially parallel to the XZ plane. Further, the displacement of the friction member 3 is transmitted to the driven body 2 by the frictional force generated between the friction member 3 and the contact member 2 d generated by the preload member 1. Here, since the friction member 3 is displaced in a direction substantially parallel to the XZ plane, the driven body 2 moves along the guide shaft 8 in the Z direction.

  The intermediate member 4 is disposed between the bending displacement member 5 and the friction member 3, thereby having a function of performing a displacement direction conversion for moving the friction member 3 in a direction different from the displacement direction of the bending displacement member 5. Yes. With this function, as shown in FIGS. 1 and 2, the bending displacement member 5 can be arranged so that the thickness direction of the bending displacement member 5 is perpendicular to the Z direction. As a result, the driving device 10 can be reduced in size in the width direction (X direction).

  The drive mechanism in the drive device 10 has a configuration for controlling the voltage applied to the bending displacement member 5 so that the reciprocating bending speed of the bending displacement member 5 is different. In this configuration, the frictional force acting between the driven body 2 and the friction member 3 is changed depending on the speed difference, and a frictional movement difference is generated between the driven body 2 and the friction member 3, thereby driving the driven body. The displacement amount (movement amount) in the Z direction of the body 2 is changed. As the drive frequency for reciprocally bending the bending displacement member 5, an ultrasonic frequency (20 kHz or more) that is several kHz or more, preferably inaudible is used. As a voltage control method, a conventionally used method may be used.

  Below, the material of the friction member 3 and the contact member 2d is demonstrated. As a material for the friction member 3 and the contact member 2d, basically, a suitable material may be selected in consideration of the friction coefficient of both, for example, a metal, a resin, a carbon sintered material, and these materials. A coated film can be used. The carbon sintered material is obtained by firing carbon at about 1000 to 3000 ° C., and generally referred to as carbon, graphite carbon, and graphite (graphite), and additives are added to these materials. It refers to things.

  More desirable materials exist for the friction member 3 and the contact member 2d. Here, the driving device 10 of the present invention drives the driven body 2 by the frictional force between the friction member 3 and the contact member 2d. Due to this friction drive, the friction member 3 and the contact member 2d have Wear and scratches are likely to occur. When wear occurs, the contact state between the friction member 3 and the contact member 2d changes, and the drive characteristics are not stable. On the other hand, when a scratch occurs, the operating characteristics change significantly due to the catch at the scratched portion, and the feed accuracy and the position reproducibility, for example, are greatly deteriorated. Receive. For this reason, as a material of the friction member 3 and the contact member 2d, what suppresses the generation | occurrence | production of abrasion and a crack by friction drive is desirable. Further, scratches are generated not only by friction drive but also by a drop impact of the drive device 10 or the like. For this reason, especially when using the drive device 10 for electronic devices, such as a mobile telephone, it is requested | required that the friction member 3 and the contact member 2d are excellent in a drop impact resistance.

  As a response to the above requirements, both the friction member 3 and the contact member 2d are made of a highly wear-resistant material, for example, a metal material such as titanium, tungsten, or stainless steel, a ceramic material such as silicon carbide (SiC), or the like. Is considered to be used. However, even when these materials are selected, a slight scratch may occur in the friction member 3 or the contact member 2d due to friction drive or drop impact, and this scratch has a fatal effect as described above. Sometimes.

  Therefore, in order to prevent the generation of scratches, it is preferable to use a soft material for either one of the friction member 3 and the contact member 2d instead of using a material with high wear resistance. For example, as can be seen from the fact that a carbon sintered material such as graphite is used for a pencil, due to its layered crystal structure, it has good lubricity and tends to wear itself. For this reason, if a carbon sintered material is used for either the friction member 3 or the contact member 2d, damage to the mating material (generation of scratches) can be prevented. Further, even if a slight scratch is generated in a member using a carbon sintered material, it can be recovered to a substantially uniform surface by wear.

  However, when one of the friction member 3 and the contact member 2d is made of a carbon sintered material, there is a problem that the amount of wear increases. Therefore, as described in the examples described later, when the combination of the materials of the friction member 3 and the contact member 2d was studied, one of the materials of the friction member 3 and the contact member 2d is a carbon sintered material, and the other Is a material having a diamond like carbon (DLC) film formed thereon, it has been found that the amount of wear is small and scratches do not occur.

  Therefore, it is preferable that one of the materials of the friction member 3 and the contact member 2d is a carbon sintered material and the other is a material on which a DLC film is formed. The DLC film is a kind of solid and highly lubricous material (solid lubricating material).

  The material of the intermediate member 4 is preferably a metal having elasticity, and for example, a metal such as stainless steel (SUS), aluminum, phosphor bronze, or the like is preferably used.

  The drive device 10 according to the present embodiment includes an optical system (such as a lens) that forms an image of an object to be imaged, and an image sensor that converts an image formed by the optical system into an electrical signal, thereby providing a camera. Such an imaging apparatus can be realized.

  Therefore, with reference to FIG. 4, a configuration in which the driven body 2 has an annular lens mounting portion 2c at the center thereof will be described below. FIG. 4 is a front view schematically showing the driven body 2 and its peripheral members.

  For example, when the driving device 10 is applied to a camera module (lens driving of an imaging device such as a camera), the driven body 2 has an annular lens mounting portion 2c at the center thereof, thereby providing a lens barrel or lens. It functions as a lens holding frame that directly holds the lens. When the driven body 2 holds the lens in the lens mounting portion 2c, the moving direction (Z direction) of the driven body 2 is the optical axis direction of the lens. Further, when the driven body 2 is driven in the optical axis direction (Z direction) by the driving mechanism of the driving device 10, an AF (autofocus) operation of the lens attached to the lens attaching portion 2c is realized.

  When the driven body 2 holds the lens, the positional accuracy of the optical center position of the lens is required to be high, that is, the positional accuracy of the optical center position H in the lens mounting portion 2c shown in FIG. The For example, in a camera module having an AF function, the positional accuracy of the optical center position of the lens is preferably ± 50 μm or less.

  Here, a case where the friction member 3 is displaced in the driving device 10 will be described. For example, as shown in FIG. 4A, consider a case where an interval of ΔX occurs between the friction member 3 and the contact member 2d in a state where the preload member 1 is not biased. FIG. 4A shows a case where the positional deviation is large so that the phenomenon can be easily understood. In the case as shown in FIG. 4A, when a preload is applied by the preload member 1, the driven body 2 is guided to the guide shaft until the friction member 3 and the contact member 2d come into contact with each other, as shown in FIG. 4B. Rotate around 8. As a result, the optical center position H changes to the optical center position H ′ shown in FIG. Further, preload is applied in a direction (Y direction) different from the original preload direction (X direction) by the preload member 1, and a driving load is generated between the guide shaft 8 and the driven body 2. For this reason, the drive characteristic of the driven body 2 becomes unstable.

  The cause of the positional deviation of the friction member 3 includes manufacturing tolerance and assembly tolerance of each member. In particular, when the bending displacement member 5 has a laminated structure of a plurality of members, the dimensional tolerance of the thickness of the bending displacement member 5 tends to increase due to the manufacturing tolerance of the lamination process.

  Therefore, the drive device 10 preferably has a configuration in which the fixed surface 5c of the bending displacement member 5 and the surface of the friction member 3 provided on the intermediate member 4 are on the same plane. According to this configuration, even if the thickness tolerance of the bending displacement member 5 is large, the distance ΔX between the friction member 3 and the contact member 2d does not increase. For this reason, the fluctuation | variation of the optical center position H can be reduced. Further, the preload direction by the preload member 1 is not inclined, and the drive device 10 having stable drive characteristics can be realized. Therefore, the drive device 10 can be suitably used for an imaging device such as a camera module.

  Another cause of the displacement of the friction member 3 is a change with time due to wear of the friction member 3 or the contact member 2d. As described above, by selecting the material of the friction member 3 and the contact member 2d from a combination of a sintered carbon material and a DLC-coated material, it is possible to reduce a change with time due to this wear. Thereby, the optical center shift of the imaging device can be reduced, and the driving stability of the driving device 10 can be improved.

  In the XY plane of the driving device 10, the distance (shortest distance) L1 between the optical center position H and the guide shaft 8 is from the distance (shortest distance) L2 between the contact point of the friction member 3 with the contact member 2d and the guide shaft 8. The position of the guide shaft 8 is preferably set so as to be shorter. The reason for this will be described with reference to FIG. The optical center position H rotates around the guide shaft 8 until the friction member 3 and the contact member 2d come into contact with each other. Therefore, by setting L1 <L2, the distance ΔX between the friction member 3 and the contact member 2d is set. The resulting shift of the optical center position H can be reduced. Further, by setting L1 <L2, the rotation angle of the driven body 2 is reduced, so that the change in the preload direction by the preloading member 1 can be reduced, and the driving characteristics of the driven body 2 can be stabilized. Connected.

  Moreover, it is preferable that the bending displacement member 5 is bonded and fixed so that only one of the surfaces bent in the bending displacement direction is in contact with the fixed wall 6a. Thereby, the position where the bending displacement member 5 is fixed is not affected by the dimensional tolerance in the longitudinal direction (Y direction) and the thickness direction (Z direction) of the bending displacement member 5. Therefore, the position of the friction member 3 does not vary in the Y direction and the Z direction. If the friction member 3 changes its position in the Y direction and the Z direction, the preload direction by the preload member 1 is applied in a direction different from the original direction (X direction), and the driven body 2 Drive characteristics become unstable. In the present embodiment, the driving characteristics of the driven body 2 can be improved by a configuration in which only one of the surfaces that are bent and mutated is fixed.

  On the other hand, a guide mechanism capable of shifting the driven body 2 in parallel with the X direction can be provided as a guide mechanism that can absorb the positional deviation even if the positional deviation occurs in the friction member 3. is there. However, such a guide mechanism requires adjustment backlash between the driven body 2 and the posture of the driven body 2 such as an inclination (tilt) is likely to occur. In particular, when the driving device 10 is used in an imaging device such as a camera module, the tilt is a major factor that degrades optical characteristics.

  Further, it is possible to absorb the displacement of the friction member 3 by moving the position of the fixed wall 6a. However, since the bending displacement member 5 vibrates at a high frequency, the fixed wall 6a is stabilized. It is preferable to arrange them.

[Embodiment 2]
A second embodiment of the present invention will be described below with reference to FIGS. FIG. 5 is a perspective view schematically showing the drive device in the second embodiment, and FIG. 6 is a perspective view showing the bending displacement member 5 and its peripheral members in the second embodiment.

  In this example, the difference from the first embodiment will be mainly described, and the same member numbers are used for the same members as in the first embodiment.

  As shown in FIG. 6, the bending displacement member 5 in the present embodiment has a shim extension portion 5 d having a configuration in which a shim member 5 a is extended to the free end side, and the shim extension portion 5 d has friction. The member 3 is fixed. The shim extension 5d has an “L” shape, and the shim extension 5d has a notch 5e. As a result, the shim member 5 a has a function of changing the bending direction, like the intermediate member 4. Therefore, also in the present embodiment, as described in the first embodiment, the bending displacement member 5 can be arranged so that the drive device 10 can be downsized.

  On the other hand, in the first embodiment, the intermediate member 4 is a separate member from the bending displacement member 5, but in this embodiment, the shim extension 5d is integral with the shim member 5a. As a result, it is not necessary to fix the intermediate member 4 with an adhesive or the like, and the number of steps for manufacturing the driving device 10 can be omitted. In addition, the number of parts is reduced, and the cost can be reduced.

  Moreover, in this embodiment, the influence by the dimensional tolerance of the member with respect to the positional accuracy of the friction member 3 reduces. Specifically, since the intermediate member 4 is not used, it is not affected by the dimensional tolerance of the intermediate member 4. Furthermore, regarding the influence due to the thickness tolerance of the bending displacement member 5, only the laminated piezoelectric element 5b on one side of the bending displacement member 5 needs to be considered, and this influence is halved compared to the first embodiment. Therefore, in the present embodiment, even when the friction member 3 is arranged on a surface different from the fixed surface 5c of the bending displacement member 5, it is possible to reduce the shift of the optical center position, the fluctuation of the preload state, and the like. Thereby, the freedom degree of design of the drive device 10 can be increased.

  Further, as shown in FIG. 5, in the present embodiment, a compression coil spring is used as the preload member 1, and the fixed wall 6 a is disposed on the opposite side to the driven body 2 with respect to the bending displacement member 5. However, the present embodiment is different from the first embodiment.

[Embodiment 3]
A third embodiment of the present invention will be described below with reference to FIG. FIG. 7 is a schematic diagram illustrating a driving device according to the third embodiment. In this example, the difference from the first and second embodiments will be mainly described, and the same member numbers as those in the first and second embodiments will be used.

  As shown in FIG. 7, in this embodiment, the driven body contact portion 2a is formed in an arm shape, and is configured to apply a preload to the driven body 2 from the bending displacement member 5 side. Thus, by changing the shape of the driven body contact portion 2a, the preload mechanism (not shown) can be changed in accordance with the shape of the driven body 2 and the like. Thereby, the arrangement of the preload mechanism and the degree of freedom in the preload direction can be increased.

  In the present embodiment, as described in the preferred embodiment 1, the fixed surface 5c of the bending displacement member 5, the surface of the intermediate member 4 provided on the bending displacement member 5, and the friction member 3 are provided. The provided surface is on the same plane. By setting it as such a structure, since the friction member 3 does not receive the influence by the thickness tolerance of the intermediate member 4, the friction member 3 can be arrange | positioned more accurately. As a result, it is possible to reduce the deviation of the optical center position and the fluctuation of the preload state.

[Embodiment 4]
A fourth embodiment of the present invention will be described below with reference to FIG. FIG. 8 is a schematic diagram illustrating a driving device according to the fourth embodiment. In addition, in a present Example, it demonstrates centering around difference with Embodiment 1-3, and the same member number shall be used for the member similar to Embodiment 1-3.

  As shown in FIG. 8, in the present embodiment, in the configuration having the shim extending portion 5d similar to that of the second embodiment, the bending displacement member 5 is fixed to the fixed wall 6a, and the friction member 3 is fixed to the shim member 5a. It is done on the same side as the front side. Thus, in the present embodiment, unlike the second embodiment, the positional accuracy of the friction member 3 in the X direction is not affected by the thickness tolerance of the bending displacement member 5 at all.

[Embodiment 5]
A fifth embodiment of the present invention will be described below with reference to FIG. FIG. 9 is a schematic diagram illustrating a driving device according to the fifth embodiment.

  In the present embodiment, the arrangement direction of the bending displacement member 5 and the moving direction of the driven body 2 are different from those of the first to fourth embodiments. Therefore, in the following, the above configuration will be mainly described. The same member numbers are used for the same members as in the first to fourth embodiments.

  The drive device of the present embodiment is configured to move the driven body 2 in the same direction as the length direction of the bending displacement member 5. Therefore, as shown in FIG. 9, in this embodiment, the longitudinal direction of the bending displacement member 5 in the stationary state is the Y direction, the thickness direction of the bending displacement member 5 is the direction perpendicular to the Y direction, and The direction. That is, the moving direction of the driven body 2 is the Y direction.

  In this embodiment, the friction member 3 is bonded and fixed to the bending displacement member 5 without the intermediate member 4 being interposed. The bending displacement member 5 is fixed to the fixed wall 6a on one surface among the surfaces bent in the bending displacement direction. The surface fixed to the bending displacement member 5 in the friction member 3 and the surface fixed to the fixed wall 6a in the bending displacement member 5 are the same plane. The fixed wall 6a is fixed to a housing (not shown).

  A contact member 2d is bonded and fixed to a side surface of the driven body 2 in the moving direction, and the contact member 2d is urged against the friction member 3 by a preload mechanism (not shown). The driven body 2 is guided in the Y direction by the main guide shaft 8a and the sub guide shaft 8b. The sub guide shaft 8b also has a role of a rotation stopper that prevents the driven body 2 from rotating.

  The bending displacement member 5 is bent and displaced in a direction substantially parallel to the XY plane by voltage application. The driven body 2 is displaced in the Y direction by the frictional force with the friction member 3 as the friction member 3 is displaced in the Y direction. The description of the drive mechanism of the drive device is the same as that in the first embodiment.

  Although the driving device in the first to fourth embodiments has a configuration suitable for the AF mechanism of the imaging device, the driving device in the fifth embodiment has a configuration suitable for the zoom mechanism of the imaging device. It has the feature that the thickness (X direction) of the apparatus can be reduced.

[Other Configurations of the Present Invention]
Further, the configuration of the drive device according to the present invention includes a bending displacement member that is fixed at one end and excited by bending displacement, and is disposed at the other end of the bending displacement member, and transmits the displacement of the bending displacement member to be covered. And a friction member that drives the drive body, wherein one end of the bending displacement member is fixed to any one of the surfaces orthogonal to the thickness direction of the bending displacement member, and the friction member is disposed. It can also be expressed as a device.

  A driving device 10 in which the materials used for the friction member 3 and the contact member 2d were combined in various ways was prepared, and 100,000 continuous operation tests were performed on the driving device 10 in each combination. The materials used and test results in each combination are described below.

(Combination A)
A carbon sintered material was used for the friction member 3, and a contact member 2d made of stainless steel (SUS304) with a DLC film was used.

  As a result of 100,000 continuous operation tests, the wear amount of the friction member 3 was 3 μm or less, and the change in the operation speed was 5% or less. The scratches were not observed on the surfaces of the friction member 3 and the contact member 2d, and no change in position reproducibility occurred. Further, even after 300,000 continuous operation tests, the change in the operation speed was maintained at 5% or less, and no change in the position reproducibility was observed.

(Combination B)
A carbon sintered material was used for the friction member 3, and stainless steel (SUS304) was used for the contact member 2d.

  As a result of 100,000 continuous operation tests, the friction member 3 was worn about 30 μm, and the operation speed was greatly changed by 45%.

(Combination C)
SiC was used for the friction member 3, and stainless steel (SUS304) was used for the contact member 2d.

  As a result of 100,000 continuous operation tests, the contact member 2d was scratched, and the position reproducibility was lowered. Further, the friction member 3 was also scratched.

(Combination D)
For both the friction member 3 and the contact member 2d, stainless steel (SUS304) provided with a DLC film was used.

  As a result of 100,000 continuous operation tests, peeling (cracking) occurred in a part of the DLC film, and the position reproducibility was lowered.

(Combination E)
A carbon sintered material was used for the friction member 3, and stainless steel (SUS304) was used for the contact member 2d. Further, a fluorine-based lubricant (Harves Co., Ltd .: Dry Surf MZ-7000EL) was applied to the contact member 2d.

  As a result of 100,000 continuous operation tests, the wear amount of the friction member 3 was 3 μm or less, and there was no problem in durability, but a speed difference of about 20% was observed between the continuous operation and the operation after the temporary stop.

  As the carbon sintered material in the above combination, a material containing 40% graphite and 60% carbon was used. In addition, as the DLC film in the above combination, a SUS304 film having a film thickness of about 1 μm was used as an intermediate layer through a Ti layer and a Si layer. The surface roughness of SUS304 used was Ra 0.1 μm, and the surface roughness was substantially equivalent even after the DLC coating.

  In addition, as combinations other than those described above, carbon sintered materials, or a combination of a carbon sintered material and glass were examined, but problems other than durability occurred such as poor initial operating characteristics.

  According to the above results, it was found that by using the sintered carbon material and the DLC film-coated material as the friction member 3 and the contact member 2d, it is possible to satisfy both the reduction of wear and the prevention of scratches (combination A). ).

  On the other hand, when carbon sintered material was combined with a material with high hardness, it was found that the carbon sintered material hardly scratches the other material, but it wears itself and adversely affects the operation speed (Combination B). .

  Further, it was found that the position reproducibility due to the generation of minute scratches on the friction surface is reduced in the combination of the materials having high hardness (combinations C and D). Since this scratch is a fatal problem, it is important to reliably prevent it, and therefore it has been found preferable to use one of the sintered carbon materials.

  Furthermore, in the combination of the sintered carbon material and the material coated with the lubricant (combination E), there was no problem of wear or scratches, but the speed was different between the initial operation after the stop and the continuous operation. became. This is considered to be because the frictional state changes due to the lubricant moving from the contact surface during continuous operation. In addition, this combination is considered to be unfavorable because a change in operating characteristics depending on the amount of lubricant applied is observed.

  Considering the above, it is clear that the material of the friction member 3 and the contact member 2d is most preferably a combination of a sintered carbon material and a material having a DLC film surface. This is considered to be because when the DLC film surface is used as a counterpart against which the carbon sintered material rubs, the wear amount of the carbon sintered material is reduced by the lubricity of the surface, which is a feature of the DLC film.

  In addition, even if it is other than a DLC film, the same effect can be obtained by using a solid and highly lubricous material (solid lubricating material). Examples of the solid lubricating material include a fluororesin (PTFE: polytetrafluoroethylene), a TiN film, and a CrN film, in addition to the DLC film. However, it is most preferable to use a DLC film because both high hardness and lubricity can be achieved.

  Further, the amount of wear varies depending on the magnitude of the preload. In the continuous operation test, the preload was set to 12 gf. Although the amount of wear can be reduced by reducing the preload, the preload has a function of bringing the driven body 2 and the friction member 3 into stable contact with each other and increasing the frictional force, and driving thrust and driving stability. This is not preferable because of a decrease in the thickness. Although the optimum value of the preload varies depending on the weight of the driven body 2, for example, when used for driving a lens of a camera module, it is preferable to set the preload between about 5 gf and 50 gf.

  In the continuous operation test, the friction member 3 is made of a carbon sintered material, and the contact member 2d is coated with the DLC film. However, the invention is not limited to this. May be applied. Further, the base material on which DLC coating is performed is not limited to SUS304, and other materials such as other stainless steel, aluminum, and silicon may be used.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  The drive device according to the present invention can be suitably used for an imaging device such as a camera module.

DESCRIPTION OF SYMBOLS 1 Preload member 2 Driven body 2d Contact member 3 Friction member 4 Intermediate member 5 Bending displacement member 5a Shim member 5b Multilayer piezoelectric element 5c Fixed surface 5d Shim extension part 6 Case 8 Guide shaft 10 Drive device

Claims (17)

A driving device for driving a driven body,
A bending displacement member having one end fixed and bending displacement excited;
A friction member that is connected to a free end of the bending displacement member and is in frictional contact with the driven body on any one surface of the bending displacement member that is bent in the bending displacement direction. The drive device characterized. One fixed end of the bending displacement member is fixed on one of the surfaces of the bending displacement member that bends in the bending displacement direction.
2. The drive according to claim 1, wherein when the fixed surface of the bending displacement member is a fixed surface, the friction member is provided on the same plane as the fixed surface in the bending displacement member. apparatus. An intermediate member that is provided at a free end of the bending displacement member and is bent and displaced in a direction different from the bending displacement member;
The friction member is provided at a free end of the intermediate member;
The drive device according to claim 1, wherein the friction member and the free end of the bending displacement member are connected via the intermediate member. One fixed end of the bending displacement member is fixed on one of the surfaces of the bending displacement member that bends in the bending displacement direction.
The surface of the intermediate member on which the friction member is provided is flush with the fixed surface when the fixed surface of the bending displacement member is a fixed surface. Drive device. The bending displacement member is formed of a displacement member whose shape displacement is excited by applying a voltage, and a shim member laminated on the displacement member,
The shim member has a shim extending portion that extends to the free end side of the bending displacement member,
The drive device according to claim 1, wherein the friction member is provided in the shim extension portion.   6. The driving apparatus according to claim 5, wherein one end of the bending displacement member fixed is on the shim member. The shim extension is formed with a notch,
The drive device according to claim 5 or 6, wherein the shim extension portion is bent and displaced in a direction different from a bending displacement direction of the bending displacement member.   The plane substantially parallel to the bending displacement direction of the intermediate member or the shim extending portion is orthogonal to the plane substantially parallel to the bending displacement direction of the bending displacement member. The driving device according to any one of the above.   9. The driving apparatus according to claim 1, wherein the friction member directly contacts the driven body.   10. The driving apparatus according to claim 1, wherein a moving direction of the driven body and a surface of the bending displacement member that is bent in the bending displacement direction are substantially parallel to each other. A fixed portion disposed between the driven body and the bending displacement member;
11. The driving device according to claim 1, wherein one end of the bending displacement member is fixed to the fixing portion.   The drive device according to any one of claims 1 to 11, further comprising a preload mechanism that biases the driven body toward the friction member. The driven body is provided with a contact member that moves integrally with the driven body and that makes frictional contact with the friction member,
2. The drive device according to claim 1, wherein one of the friction member and the contact member is formed with a film made of a solid lubricating material, and the other is formed of a carbon sintered material.   14. The driving apparatus according to claim 13, wherein the film made of the solid lubricating material is a diamond-like carbon film. The drive device according to any one of claims 1 to 14,
An optical system for imaging an object to be imaged;
An image sensor that converts an image formed by the optical system into an electrical signal, and
The image pickup apparatus, wherein the driven body holds the optical system. A driving shaft for supporting the driving of the driven body;
The shortest distance between the optical axis of the optical system and the drive shaft is shorter than the shortest distance between a contact point of the friction member with the driven body and the drive shaft. 15. The imaging device according to 15.   An electronic apparatus comprising the drive device according to any one of claims 1 to 14 or the imaging device according to claim 15 or 16.

Images