JP2007181260A - Drive unit and camera module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive unit, which enables size reduction in the direction of the expansion and contraction of an electromechanical conversion element, and to provide a camera module. <P>SOLUTION: This drive unit is equipped with the electromechanical conversion element (electrostrictive element 7) which expands and contracts in a specified direction by electric input, a frictionally engaging member 9, which is fixed to one end side in the direction of expansion and contraction of the electrostrictive element 7, a driven member 4A which is frictionally engaged by the frictionally engaging member 9, and an imaging lens unit 1, which is a mobile object fixed to the driven member 4A. The frictionally engaging member 9 has a shape of a pillar which extends substantially parallel, in the direction of expansion and contraction of the electrostrictive element 7. The electrostrictive element 7 and the frictionally engaging member 9 are fixed via a coupling member 8, consisting of a rigid body so that the frictionally engaging member 9 is arranged at a position which is off the axial extension of the electrostrictive element 7. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a drive unit and a camera module using an electromechanical conversion element that expands and contracts in a predetermined direction by an electric input, and more particularly to a drive unit and a camera module that are miniaturized in the expansion and contraction direction of the electromechanical conversion element.

  In recent years, information devices have been refined, and there is an increasing demand for drive units that require minute movement distances on the order of submicrons or nanometers. As a commonly used drive unit, an electromechanical transducer that deforms when supplied with electrical energy is used, and a slider is movably moved along the drive shaft against a drive shaft that reciprocates or expands and contracts. There is a linear actuator that engages and drives the drive shaft in a front-rear asymmetric manner to move the slider in an arbitrary front-rear direction. Such a friction drive type drive unit is low speed but has high torque and excellent response and controllability, enables fine positioning, has a holding torque (or holding force) when not energized, and has excellent quietness. It has advantages such as small size and light weight, and is used in a wide range of fields such as auto focus and change of focal length (zoom) in a camera module.

The drive unit as described above is disclosed in Non-Patent Document 1 and the like. As shown in FIG. 8, the electrostrictive element 52 fixed to the fixing member 51, the friction engagement member 53 attached to one end side of the electrostrictive element 52, and the friction of the friction engagement member 53 It is an actuator comprised from the moving body 54 engaged with the site | part so that sliding was possible. The operating principle of such an actuator is to apply a voltage to the electrostrictive element 52 and input a sawtooth or rectangular voltage waveform to control the expansion and contraction of the electrostrictive element 52, thereby slowly extending the electrostrictive element 52. And the moving body 54 move together due to friction, and when the electrostrictive element 52 is rapidly contracted, the frictional portion of the moving body 54 slips due to inertia and stays at that position. By repeating this, the moving body 54 moves. Further, the electrostrictive element 52 is operated in the opposite direction by repeating the operation of rapidly extending and slowly contracting the electrostrictive element 52.
As a result, it is possible to obtain a drive unit that is more accurate and smaller than the conventionally used actuators such as electromagnetic motors.

“Development of ultra-small piezoelectric actuator (SIDM)”, Konica Minolta Technology Report vol. 1 (2004)

However, in the conventional drive unit using the electrostrictive element as described in Non-Patent Document 1 or the like, the long-axis friction engagement member is arranged on the extension line in the expansion / contraction direction of the electrostrictive element. There was a limit to the miniaturization of the electrostrictive element in the direction of expansion and contraction. Therefore, when applied to the AF function, zoom function, etc. in the camera module, the length of the electrostrictive element and the drive shaft must be secured, so there is a limit to thinning in the optical axis direction, and the electrostrictive element and the drive are limited. Since the shafts need to be arranged on the same axis, there is a problem that the layout of other parts is limited.
Accordingly, it is an object of the present invention to provide a drive unit and a camera module that can be miniaturized in the expansion / contraction direction of the electromechanical conversion element and can give a degree of freedom to the arrangement of the components.

Therefore, in order to solve such a problem, the present invention provides an electromechanical conversion element that expands and contracts in a predetermined direction by electric input, a coupling member that is fixed to one end of the electromechanical conversion element in the expansion and contraction direction, and is fixed to the coupling member. A friction engagement member, a driven portion that frictionally engages with the friction engagement member and moves along the expansion / contraction direction by expansion / contraction of the electromechanical conversion element, and the drive portion A moving body,
The friction engagement member has a columnar shape, and is disposed so as to extend substantially parallel to the expansion / contraction direction at a position deviated from an extension line in the expansion / contraction direction of the electromechanical transducer.

In addition, the electromechanical conversion element that expands and contracts in a predetermined direction by electric input, a coupling member that is fixed to one end of the electromechanical conversion element in the expansion and contraction direction, a friction engagement member that is fixed to the coupling member, and the friction engagement A driven part that frictionally engages with a combined member and moves along the direction of expansion and contraction due to expansion and contraction of the electromechanical conversion element, and is formed separately from the driven part and can move integrally with the driven part A moving body,
The friction engagement member has a columnar shape, and is disposed so as to extend substantially parallel to the expansion / contraction direction at a position deviated from an extension line in the expansion / contraction direction of the electromechanical transducer.

According to the present invention, the frictional engagement member is disposed at a position different from the axial extension line of the electromechanical conversion element via the coupling member. be able to. Further, the frictional engagement member may be disposed anywhere other than the axis extension line of the electromechanical conversion element and substantially parallel to the expansion / contraction direction, thereby allowing other components to be freely laid out. Furthermore, the driving force can be efficiently transmitted by disposing the friction engagement member substantially parallel to the expansion / contraction direction of the electromechanical transducer.
Examples of the electromechanical transducer include an electrostrictive element that expands and contracts by application of a voltage, and a magnetostrictive element that expands and contracts by a magnetic field generated by supplying a current. Moreover, the rigid body which comprises a coupling member has the rigidity of the grade which does not produce a bending with respect to expansion / contraction of an electromechanical conversion element. By configuring the coupling member as a rigid body, the electromechanical conversion element and the friction engagement member can be maintained in a parallel state with high accuracy and the driving force can be transmitted efficiently.
In the present invention, when the driven part is formed integrally with the movable body, the number of parts can be reduced, the assembly is facilitated, and the shake due to the swing during operation does not occur, so that the coaxiality can be kept high.
On the other hand, when the moving body is formed separately from the driven part and fixed, the cost can be reduced because the parts are easily manufactured.

Further, the driven part and the moving body are configured as separate bodies, and the driven part and the moving body are fixed by a pressing member.
Furthermore, at least one of the contact surfaces of the pressing member, the driven portion, and the movable body is a spherical pedestal in which a convex spherical surface and a concave spherical surface are fitted. As a result, the coaxiality of the moving body can be ensured regardless of the incorporation variation of the electromechanical conversion element, the component variation, and the shake due to expansion and contraction, and a highly accurate drive unit can be provided.

In addition, a pressing member that applies a pressing force to the frictional sliding surface between the driven portion and the friction engagement member from the outer peripheral side of the driven portion is provided.
As a result, an appropriate pressing force can be applied to the frictional sliding surfaces of the frictional engagement member and the driven portion, the frictional force can be easily controlled, and the moving body can be smoothly driven and highly accurately positioned. It becomes possible.

Further, the tilting unit includes a guide shaft provided at a fixed portion of the drive unit, and a guide shaft support portion provided at a position separated from the driven portion fixed to the movable body and configured to slide and support the guide shaft. A prevention mechanism is provided.
According to this, the moving body is supported at two points by the friction engagement member and the fall prevention mechanism, and the coaxiality of the moving body is ensured, and a highly accurate drive unit can be obtained.

Still further, it is provided with a fall prevention mechanism comprising one end side of the friction engagement member and a friction engagement member support portion which is provided at a fixed portion of the drive unit and which slide-supports the one end side. .
Thus, by providing a guide function on one end side of the friction engagement member, the coaxiality of the moving body can be ensured and a highly accurate drive unit can be obtained.

Further, as an invention of the camera module, an electromechanical conversion element that expands and contracts in a predetermined direction by electrical input, a coupling member that is fixed to one end of the electromechanical conversion element in the expansion and contraction direction, and a friction engagement that is fixed to the coupling member A member, a driven portion that frictionally engages with the friction engagement member and moves along the expansion / contraction direction by expansion / contraction of the electromechanical conversion element, and an optical system formed integrally with the driven portion. Become
The friction engagement member has a columnar shape, and is disposed so as to extend substantially parallel to the expansion / contraction direction at a position deviated from an extension line in the expansion / contraction direction of the electromechanical transducer.

In addition, the electromechanical conversion element that expands and contracts in a predetermined direction by electric input, a coupling member that is fixed to one end of the electromechanical conversion element in the expansion and contraction direction, a friction engagement member that is fixed to the coupling member, and the friction engagement A driven part that frictionally engages with a combined member and moves along the direction of expansion and contraction due to expansion and contraction of the electromechanical conversion element, and is formed separately from the driven part and can move integrally with the driven part With an optical system,
The friction engagement member has a columnar shape, and is disposed so as to extend substantially parallel to the expansion / contraction direction at a position deviated from an extension line in the expansion / contraction direction of the electromechanical transducer.
According to the present invention, it is possible to provide a camera module in which the optical axis direction is smaller than that of the conventional one, and thus it is possible to reduce the thickness of devices such as a digital camera and a camera-equipped mobile phone.
Further, the friction engagement member is located closer to the electromechanical conversion element than the coupling member. Thus, by positioning the fixed portion of the friction engagement member on the electromechanical conversion element side and positioning the coupling member that reciprocates as the friction engagement member expands and contracts on the optical system side, the connecting portion of each member is A camera module that can be simplified and more miniaturized can be provided.

As described above, according to the present invention, the frictional engagement member is arranged at a position different from the axial extension line of the electromechanical conversion element by the coupling member. Can be a unit. Further, the frictional engagement member may be disposed anywhere other than the axis extension line of the electromechanical conversion element and substantially parallel to the expansion / contraction direction, thereby allowing other components to be freely laid out.
In addition, by providing a mechanism for preventing the mobile body from falling down, the coaxiality of the mobile body can be secured and a highly accurate drive unit can be obtained.
Furthermore, by applying to a camera module, it is possible to provide a camera module whose optical axis direction is smaller than conventional ones, and it is possible to reduce the thickness of devices such as digital cameras and camera-equipped mobile phones.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.
1 is an exploded perspective view of the camera module according to the first embodiment, FIG. 2 is a perspective view of the camera module according to the first embodiment, FIG. 3 is a side sectional view of the camera module according to the first embodiment, and FIG. 5 is an exploded perspective view of the camera module according to the second embodiment, FIG. 5 is a perspective view of the camera module according to the second embodiment, FIG. 6 is an enlarged view of a main part of the camera module according to the second embodiment, and FIG. 6 is a side sectional view of a camera module according to Example 2. FIG.
In this embodiment, a camera module in which an optical system is applied to a moving body is described and illustrated as an example. However, the present invention is not limited to this, and the present invention is not limited to this and is used as a linear actuator that requires high-precision positioning. Applicable to all drive units.

  As shown in FIGS. 1 to 3, the driving unit according to the present embodiment includes a moving body such as the imaging lens unit 1, a driven member 4A fixed to the moving body, and friction between the driven member 4A and the driven member 4A. Friction engagement member 9 to be engaged, electromechanical conversion element such as electrostrictive element 7, coupling member 8 made of a rigid body connecting friction engagement member 9 and electrostrictive element 7, moving body 1 and driven member A pressing member 5A that presses and fixes 4A is a main component. Further, these camera modules are housed in the casing 10. A bottom cover 13 having an image sensor 14 is attached to the bottom surface of the casing 10, and a position detection sensor 15 for detecting the position of the imaging lens unit 1 is attached to the side surface.

In this embodiment, the electromechanical conversion element (electrostrictive element 7), the coupling member 8, and the friction engagement member 9 are integrated to form the electrostrictive unit 6.
In the present embodiment, the electromechanical conversion element is exemplified by the electrostrictive element 7, but any electrostrictive element can be used as long as it is a member that expands and contracts in a predetermined direction by electric input, and an electrostrictive element or a magnetostrictive element can be used. . One end of the electrostrictive element 7 is fixed to the casing 10, and a friction engagement member 9 is fixed to the other end side via a coupling member 8. Each coupling surface is fixed by adhesion or press-fitting (embedding). The coupling member 8 is made of a rigid body, and has a rigidity that does not cause deflection with respect to expansion and contraction of the electrostrictive element 7. By configuring the coupling member 8 as a rigid body, the electrostrictive element 7 and the frictional engagement member 9 can be accurately maintained in a parallel state. In particular, as a rigid body that can be suitably used for the coupling member 8 of the present embodiment, a rigid body having a rigidity of 10 × 10 ¹⁰ Pa or more is preferable.
The friction engagement member 9 has a columnar shape and is fixed to one end side of the electrostrictive element 7, but at a position deviated from the axial extension line of the electrostrictive element 7 by the coupling member 8 in the expansion / contraction direction of the electrostrictive element 7. It is arranged substantially in parallel. Specifically, as shown in the figure, the electrostrictive element 7, the friction engagement member 9 arranged in parallel to the side of the electrostrictive element 7, and the same side of the electrostrictive element 7 and the friction engagement member 9 It is preferable that the U-shaped electrostriction unit 6 has one end thereof connected and fixed by a plate-like coupling member 8.

The imaging lens unit 1 that is a moving body includes an imaging lens and a lens holding frame that holds the lens. In this case, the imaging lens unit 1 is slightly moved in the optical axis direction to perform autofocus and change in focal length (zoom). Further, the imaging lens unit 1 is provided with a guide support portion 2 and an attachment portion 3 on the outer peripheral surface thereof.
The attachment portion 3 is configured integrally with the imaging lens unit 1, and is used to fix the driven member 4A and the imaging lens unit 1 configured separately from each other by the pressing member 5A.
The guide shaft support portion 2 is formed with a hole portion having a diameter substantially the same as the diameter of the guide shaft 11 fixed to the casing 10 so that the inner surface of the hole portion and the guide shaft 11 slide.

The driven member 4A has a substantially rectangular parallelepiped shape in which a hole having a diameter substantially the same as the diameter of the friction engagement member 9 is formed, and the inner surface of the hole and the outer peripheral surface of the friction engagement member 9 are frictionally slid. It is like that. The hole inner peripheral surface of the driven member 4 </ b> A is surface-treated so as to receive a constant frictional force from the outer peripheral surface of the friction engagement member 9.
At least a part of the driven member 4A and the attachment portion 3 are overlapped with each other and fixed by the pressing member 5A. The pressing member 5A is preferably a U-shaped leaf spring that presses and fixes one surface of the attachment portion 3 and one surface of the driven member 4A. Accordingly, the driven member 4A and the imaging lens unit 1 are configured to move integrally.

  In addition, a drive unit including these components is housed in a casing 10, and an image sensor 14 is provided on a bottom cover 13 attached to the bottom surface of the casing 10. The imaging element 14 is an element that forms an optical image by the imaging lens unit 1 and outputs a signal corresponding to the formed optical image, and may be a CCD or a CMOS sensor. Further, a position detection sensor 15 that detects the position of the imaging lens unit 1 is provided on a side surface of the casing 10. Based on the position of the imaging lens unit 1 detected by the position detection sensor 15, the electrical system for applying a voltage to the electrostrictive element 7 is controlled to appropriately move the imaging lens unit 1.

The camera module including the drive unit shown in this configuration includes a steep volume change of the electrostrictive element 7, a friction engagement member 9 connected to the electrostrictive element 7, and a driven member fixed to the imaging lens unit 1. By utilizing the inertia and frictional force of 4A, it is possible to drive with small size and high accuracy, and to precisely position the lens.
The driving principle of the lens moving operation by the electrostrictive element 7 is as follows.
When the electrostrictive element 7 extends rapidly, the frictional engagement member 9 connected to the electrostrictive element 7 rapidly moves simultaneously, and the outer peripheral surface of the columnar frictional engagement member 9 and the imaging lens unit 1 are moved. The inner peripheral surface of the hole portion of the connected driven member 4A slips, and the imaging lens unit 1 itself remains substantially in that position, and only the friction engagement member 9 moves. Thereafter, when the electrostrictive element 7 is contracted slowly, the driven member 4A is accompanied by the imaging lens unit 1 in the Z-axis-direction (by the surface friction between the outer peripheral surface of the friction engagement member 9 and the inner peripheral surface of the driven member 4A). (See Fig. 2). By repeating this expansion / contraction operation, the imaging lens unit 1 is displaced in the Z-axis direction. Similarly, when the electrostrictive element 7 is slowly extended and then rapidly contracted, the imaging lens unit 1 moves in the Z-axis + direction (see FIG. 2). At this time, in order to displace the electrostrictive element 7, a rectangular or sawtooth asymmetric voltage waveform is input to the electrostrictive element 7 and controlled by a circuit board (not shown).

  Specifically, for example, when an asymmetric voltage pulse whose fall time is longer than the rise time is applied to the electrostrictive element 7, the pulse rises due to friction between the inner peripheral surface of the friction engagement member 9 and the outer peripheral surface of the driven member 4A. At the time of lowering, the friction engagement member 9 and the driven member 4A return to the starting position while being engaged, so that the friction engagement member 9 and the driven member 4A move relative to each other at the time of the rise of the pulse. When the rise and fall times of the voltage are applied in reverse, the electrostrictive element 7 is deformed in the reverse order, so that the friction engagement member 9 and the driven member 4A move in the opposite directions. To do. The displacement width of the imaging lens unit 1 can be freely set according to the length of the friction engagement member 9. If it is within the range of the displacement width set based on the length of the frictional engagement member 9, the imaging lens unit 1 can be moved minutely.

  In this manner, the electrostrictive element is applied with a signal voltage that continuously deforms, thereby causing relative friction due to surface friction between the outer peripheral surface of the friction engagement member 9 and the inner peripheral surface of the driven member 4A. Since the position is displaced, it is possible to perform minute positioning with excellent responsiveness and controllability, having holding torque (or holding force) when no current is applied, excellent quietness, small size and light weight. It becomes the drive source which has. At this time, control is performed based on the position detected by the position detection sensor 15 provided on the side surface of the casing 10.

In this configuration, the frictional engagement member 9 is arranged in a U shape via the coupling member 8, and the frictional engagement member 9 is arranged at a position different from the axial extension line of the electrostrictive element 7. The direction can be reduced, and a low-profile drive unit can be obtained. Further, the frictional engagement member 9 may be arranged anywhere other than the axial extension line of the electrostrictive element 7 as long as it is substantially parallel to the expansion / contraction direction, thereby allowing other components to be freely laid out.
Furthermore, by applying the drive unit to the camera module as in this embodiment, it is possible to provide a camera module whose optical axis direction is smaller than that of the conventional one, and thus a device such as a digital camera or a camera-equipped mobile phone. Can be made thinner.

  Also, as shown in FIG. 3, at least one of the contact surfaces of the driven member 4A, the attachment portion 3, and the pressing member 5A is a spherical pedestal in which a convex spherical surface and a concave spherical surface are fitted. Is preferred. That is, the contact surface 30 between the driven member 4A and the mounting portion 3 is a spherical pedestal, and the contact surface 40 between the driven member 4A and the pressing member 5A is a spherical pedestal. Thereby, the coaxiality of the imaging lens unit 1 can be ensured regardless of the variation in incorporation of the electrostrictive unit 6 and the vibration accompanying expansion and contraction, and a highly accurate drive unit can be provided.

  Further, in the camera module as in the present embodiment, in order to prevent one side blur of the lens, the perpendicular of the light receiving surface of the image sensor 14 and the optical axis of the lens are not inclined as much as possible (for example, within 0.05 degrees). Must be guaranteed. Therefore, a fall prevention mechanism including the guide shaft 11 and the guide shaft support portion 2 is provided. The fall prevention mechanism includes a guide shaft 11 fixed to the casing 10 and extending parallel to the optical axis, and a guide shaft support portion 2 fixed to the imaging lens unit 1 and slidably supported with respect to the guide shaft 11. Is done. The guide shaft support portion 2 may be provided separately from the driven member 4A. The sliding portion between the guide shaft 11 and the guide shaft support portion 2 can reduce the tilt between the lens and the normal of the light receiving surface of the image sensor 14 as the gap is small within a range that does not affect driving, and a camera module with good performance can be obtained. Obtainable. That is, the guide shaft support portion 2 has a hole portion 2a having a shape and size matching the guide shaft 11, and the guide shaft 11 is slidable in the hole portion 2a. The guide shaft 11 is received by the guide shaft support portion 2 fixed to the imaging lens unit 1 to prevent the shaft from falling.

Furthermore, as another structure of the fall prevention mechanism, as shown in FIG. 7 (not shown in FIGS. 1 to 3), one end side of the friction engagement member 9 on the side not fixed to the coupling member 8; You may make it provide the fall prevention mechanism which consists of the friction engagement member support part 12 which is provided in the casing 10 and slidably supports the said one end side.
The imaging element 14 is fixed to the casing 10, and the friction engagement member support portion 12 provided on the lower side (the bottom cover 13 side) of the casing 10 slides with one end of the friction engagement member 9. Similar to the guide shaft support portion 2, the sliding portion has a smaller gap within a range that does not affect driving, and the tilt between the lens and the perpendicular to the light receiving surface of the image sensor 14 can be reduced, and a camera module with good performance can be obtained. be able to. That is, the friction engagement member support portion 12 has a hole portion 12a having a shape and a size aligned with one end of the columnar friction engagement member 9, and one end of the friction engagement member 9 slides in the hole portion 12a. It is possible to prevent the shaft from collapsing by receiving one end of the friction engagement member 9 at the friction engagement member support portion 12 provided in the casing 10. The overlap between the friction engagement member support portion 12 and one end of the friction engagement member 9 is set so that it does not come off even when the friction engagement member 9 is driven. In addition, the transmission efficiency of the motion is improved as the tilt of the engagement portion between the friction engagement member 9 and the driven member 4A is reduced. If the frictional engagement member 9 is not tilted, it is possible to eliminate the troublesomeness of adjusting and incorporating the electrostrictive element 5.
The camera module of the present embodiment preferably has a configuration including one or both of the above-described two fall prevention mechanisms.

4 to 7 show a drive unit according to the second embodiment. In the second embodiment, detailed description of the same configuration as that of the first embodiment will be omitted.
The drive unit according to the second embodiment includes an imaging lens unit 1, a driven portion 4B fixed to the imaging lens unit 1, a friction engagement member 9 that frictionally engages the driven portion 4B, and electrostriction. A coupling member 8 made of a rigid body that couples the element 7, the friction engagement member 9 and the electrostrictive element 7, a pressing member 5B that applies a pressing force to the friction sliding surface from the outer peripheral side of the driven portion 4B, Is the main component. Further, these camera modules are housed in a casing 10, a bottom cover 13 having an image sensor 14 is attached to the bottom surface of the casing 10, and a position detection sensor 15 that detects the position of the imaging lens unit 1 on the side surface. Is installed.

The driven portion 4B has a substantially rectangular parallelepiped shape that is directly fixed to the imaging lens unit 1 or integrally formed with the unit 1, and a hole portion having a diameter substantially the same as the diameter of the friction engagement member 9 is formed. Has been. The hole is preferably opened with a notch. The inner peripheral surface of the hole portion of the driven portion 4B is surface-treated so as to receive a constant frictional force from the outer peripheral surface of the friction engagement member 9. The inner surface of the hole and the friction engagement member 9 are slidable by friction.
Moreover, the side surface where the notch of the driven part 4B does not exist is pressed by the pressing member 5B. As shown in FIG. 6, the pressing member 5B has a U-shape and surrounds the three side surfaces of the driven portion 4B to apply a predetermined pressure to the frictional sliding surfaces of the friction engagement member 9 and the driven portion 4B. It is preferable to adopt a configuration to do so. As a result, an appropriate pressing force can be applied to the frictional sliding surfaces of the friction engagement member 9 and the driven portion 4B, the frictional force can be easily controlled, and the imaging lens unit 1 can be driven smoothly and high. Accurate positioning is possible.

Similarly to the first embodiment, it is preferable that a fall prevention mechanism is provided by the guide shaft 11 provided in the casing 10 and the guide shaft support portion 2 provided in the imaging lens unit 1.
Furthermore, as another configuration of the fall prevention mechanism, one end of the friction engagement member 9 on the side not fixed to the coupling member 8, and a friction engagement member support portion 12 provided on the casing 10 for slidingly supporting the one end, You may make it provide the fall prevention mechanism which consists of.
Among these fall prevention mechanisms, it is preferable to include at least one mechanism, thereby ensuring the coaxiality of the imaging lens unit 1 and providing a highly accurate drive unit.

  Since the present invention can be miniaturized in the driving direction, a camera module incorporating an autofocus (AF) function or a zoom function can be thinned and configured as a camera module in various small portable terminals. Is optimal.

It is a disassembled perspective view of the camera module which concerns on Example 1 of this invention. It is a perspective view of the camera module which concerns on Example 1 of this invention. It is a sectional side view of the camera module which concerns on Example 1 of this invention. It is a disassembled perspective view of the camera module which concerns on Example 2 of this invention. It is a perspective view of the camera module which concerns on Example 2 of this invention. It is a principal part enlarged view of the camera module which concerns on Example 2 of this invention. It is a sectional side view of the camera module which concerns on Example 2 of this invention. It is a block diagram of the conventional electrostrictive actuator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Imaging lens unit 2 Guide shaft support part 3 Attachment part 4A Driven member 4B Driven part 5A, 5B Press member 6 Electrostrictive unit 7 Electrostrictive element 8 Coupling member 9 Friction engagement member 10 Casing 11 Guide shaft 12 Friction engagement Member support portion 13 Bottom cover 14 Image sensor 15 Position detection sensor

Claims (10)

An electromechanical transducer that expands and contracts in a predetermined direction by electrical input, a coupling member that is fixed to one end of the electromechanical transducer in the expansion and contraction direction, a friction engagement member that is fixed to the coupling member, and the friction engagement member A driven portion that is frictionally engaged with the electromechanical conversion element and moves along the expansion / contraction direction due to expansion / contraction of the electromechanical conversion element, and a movable body that is formed integrally with the driven portion,
The drive unit characterized in that the friction engagement member has a columnar shape and is disposed so as to extend substantially parallel to the expansion / contraction direction at a position deviated from an extension line in the expansion / contraction direction of the electromechanical conversion element. . An electromechanical transducer that expands and contracts in a predetermined direction by electrical input, a coupling member that is fixed to one end of the electromechanical transducer in the expansion and contraction direction, a friction engagement member that is fixed to the coupling member, and the friction engagement member And a driven part that is frictionally engaged with the electromechanical conversion element and moves along the direction of expansion and contraction, and a movement that is formed separately from the driven part and that can move integrally with the driven part. The body, and
The drive unit characterized in that the friction engagement member has a columnar shape and is disposed so as to extend substantially parallel to the expansion / contraction direction at a position deviated from an extension line in the expansion / contraction direction of the electromechanical conversion element. .   The drive unit according to claim 2, wherein the driven part and the movable body are fixed by a pressing member.   The contact surface of at least any one of each of the said pressing member, the said to-be-driven part, and the said moving body is a spherical base with which the convex spherical surface and the concave spherical surface were fitted. Drive unit.   3. The drive unit according to claim 1, further comprising a pressing member that applies a pressing force to a friction sliding surface between the driven portion and the friction engagement member from an outer peripheral side of the driven portion. .   A fall prevention mechanism comprising a guide shaft provided at a fixed portion of the drive unit and a guide shaft support portion provided at a position separated from the driven portion fixed to the movable body and slidably supporting the guide shaft. The drive unit according to any one of claims 1 to 5, further comprising:   2. A fall prevention mechanism comprising one end side of the friction engagement member and a friction engagement member support portion provided at a fixed portion of the drive unit and slidingly supporting the one end side. The drive unit according to any one of 1 to 6. An electromechanical transducer that expands and contracts in a predetermined direction by electrical input, a coupling member that is fixed to one end of the electromechanical transducer in the expansion and contraction direction, a friction engagement member that is fixed to the coupling member, and the friction engagement member A driven part that is frictionally engaged and moves along the direction of expansion and contraction due to expansion and contraction of the electromechanical conversion element, and an optical system that is formed integrally with the driven part,
The camera module characterized in that the friction engagement member has a columnar shape and is disposed so as to extend substantially parallel to the expansion / contraction direction at a position deviated from an extension line in the expansion / contraction direction of the electromechanical conversion element. . An electromechanical transducer that expands and contracts in a predetermined direction by electrical input, a coupling member that is fixed to one end of the electromechanical transducer in the expansion and contraction direction, a friction engagement member that is fixed to the coupling member, and the friction engagement member And a driven part that moves along the direction of expansion and contraction due to the expansion and contraction of the electromechanical conversion element, and an optical element that is formed separately from the driven part and that can move integrally with the driven part The system,
The camera module characterized in that the friction engagement member has a columnar shape and is disposed so as to extend substantially parallel to the expansion / contraction direction at a position deviated from an extension line in the expansion / contraction direction of the electromechanical conversion element. .   The camera module according to claim 8, wherein the friction engagement member is positioned closer to the electromechanical conversion element than the coupling member.

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