JP2005143277A - Vibration-type actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibration-type actuator that can mainly absorb unnecessary vibration. <P>SOLUTION: The vibration-type actuator is provided with a vibrating body that comprises at least an electricity-mechanical energy conversion element (4), and excites vibration by the application of a frequency signal to the electricity-mechanical energy conversion element; a contact body (7) that contacts with the vibrating body; and an energization means (10) that energizes the contact body to the vibrating body. The vibration-type actuator relatively rotates the vibrating body and the contact body around a specified axis by vibration excited by the vibrating body. The energization means is formed by being wound with a long-length member alternately having peaks and bottoms around the specified axis, at least the three peaks or the three bottoms are positioned in a plane that is orthogonal to the specified axis, and the peaks and the bottoms are in contact with each other in the direction of the specified axis. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a vibration type actuator that applies a frequency signal to an electro-mechanical energy conversion element such as a piezoelectric element to excite vibration in a vibrating body and relatively drives the vibrating body and a contact body.

  The vibration wave motor excites vibration in a vibrating body and drives a rotor brought into pressure contact with the vibrating body by frictional force between the vibrating body and the rotor.

Here, in the conventional vibration wave motor, as shown in FIG. 2, the rotor 7 is brought into pressure contact with the vibrating body composed of the piezoelectric element 4 and the elastic body 5 by the biasing force of the coil spring 10. (For example, refer to Patent Document 1). In addition, as shown in FIG. 3, there is a type in which the rotor 106 is pressed and brought into contact with a vibrating body composed of the piezoelectric element 102 and the elastic body 101 using a leaf spring 108 (see, for example, Patent Document 2).
JP 2002-354849 A (paragraph number 0018, FIG. 1 etc.) Japanese Unexamined Patent Publication No. 2003-47263 (paragraph number 0029, FIG. 1, etc.)

  However, in the above-described vibration wave motor using the coil spring, even if the end surface of the coil spring is ground, the applied pressure at each point on the circumference of the both end surfaces of the coil spring is different. It is impossible to apply a uniform pressure to the end face. Further, if the number of turns of the coil spring is increased, the coil spring is inclined with respect to the output shaft, and a uniform pressure cannot be applied to the end face of the rotor.

  As a result, pressure distribution unevenness is caused by unnecessary vibrations other than traveling waves transmitted from the vibrating body to the rotor, causing abnormal vibrations and rotational slips, and resonating as operation sounds.

  Further, in the vibration wave motor using a leaf spring, the pressure applied to the rotor is not stable, and a separate pressure adjusting mechanism is required to stabilize the pressure, which increases the number of parts. There is. Moreover, since the spring constant of the leaf spring is larger than that of a coil spring or the like, a sudden torque change occurs due to the pressure applied to the rotor, which causes a problem in improving the life of the vibration wave motor.

  The present invention includes at least an electro-mechanical energy conversion element, a vibration body that excites vibrations by applying a frequency signal to the electro-mechanical energy conversion element, a contact body that contacts the vibration body, and the contact body And a biasing means that biases the vibrating body relative to a specific axis by vibration excited by the vibrating body, the biasing means comprising: And a long member having alternating troughs is formed by multiple winding around a specific axis, and at least three crests or troughs are located in a plane perpendicular to the specific axis. The crest and trough are in contact with each other in a specific axial direction.

  According to the vibration type actuator of the present invention, since at least three peaks or valleys in the biasing means are located in a plane perpendicular to the specific axis, a uniform biasing force is applied to the contact body. Rotation unevenness when the contact body and the vibration body rotate relative to each other can be suppressed, thereby reducing noise caused by rotation unevenness and wear at the contact portion between the contact body and the vibration body (improving the life of the vibration actuator) Can be made. Here, if at least three peaks and valleys are positioned at equal intervals around a specific axis, a uniform biasing force can be applied to the contact body.

  Moreover, since the ridges and the valleys in the urging means are in contact with each other in a specific axial direction, the contact portion in the urging means can be increased as compared with the conventional coil spring. The vibration can be converted into thermal energy in step 1, and unnecessary vibration when the vibration type actuator is driven can be absorbed.

  Further, in the structure of the urging means of the present invention, a long member is formed by multiple winding around a specific axis, and the spring constant is larger than that of a leaf spring provided in a conventional vibration type actuator. Since the pressure can be reduced, it is not necessary to provide a pressure adjusting mechanism, and the vibration type actuator can be reduced in size and cost.

  Furthermore, in the structure of the urging means according to the present invention, the peak portion and the valley portion are in contact with each other in the specific axial direction, so that the length of the urging means in the specific axial direction is shorter than that of the conventional coil spring. If the biasing means having this structure is provided in the vibration type actuator, the vibration type actuator can be reduced in size.

  Here, if the cross section of the long member constituting the urging means is formed so that the length in the radial direction of the urging means is longer than the length in the specific axial direction, the peak portion and the valley portion The contact area can be increased, and the effect of absorbing unwanted vibrations can be enhanced.

  In addition, an optical sensor having a light projecting unit and a light receiving unit in the vibration type actuator, a reflecting member that reflects light from the light projecting unit to the light receiving unit side, and operates according to relative driving of the vibrating body and the contact body, Can reduce the component placement space in the vibration type actuator and reduce the size of the vibration type actuator compared to the configuration in which the light projecting part and the light receiving part are provided on both sides of the reflecting member. it can.

  Further, by providing at least a groove portion for accommodating the pressurizing means in the contact body, the pressurizing means can be arranged in a space-efficient manner in the vibration type actuator, and the vibration type actuator can be reduced in size by at least the provision of the groove portion. be able to.

  Examples of the present invention will be described.

  FIG. 1 is a sectional view of a vibration wave motor that is Embodiment 1 of the present invention. The vibration wave motor of this embodiment is a type of motor having an output shaft.

  In FIG. 1, reference numeral 1 denotes a housing to which members described later are attached. Reference numeral 2 denotes a bearing member that supports one end of the output shaft 14, and is fixed by press-fitting into a recess formed in the outer cylinder 13 that constitutes the exterior of the vibration wave motor. The outer cylinder 13 is fixed to the housing 1 by press fitting.

  The elastic body 5 is formed in an annular shape, and a slider (friction material) 6 is fixed to the surface of the elastic body 5 on the rotor (contact body) 7 side by adhesion, and the surface on the opposite side to the rotor 7 side. A piezoelectric element (electro-mechanical energy conversion element) 4 is fixed by adhesion. The elastic body 5 is fixed to the housing 1 by caulking.

  Here, the radially inner region of the elastic body 5 is thinner than the outer region (the region in contact with the piezoelectric element 4) as will be described later, and the elastic body 5 passes through the inner region. The housing 1 is fixed. Thereby, compared with the case where the thickness of the inner area | region in the elastic body 5 is thickened, attenuation | damping of the bending vibration which generate | occur | produces in the elastic body 5 can be suppressed to the minimum.

  The piezoelectric element 4 has a two-phase driving phase formed by a known polarization process. In addition, a flexible printed board 3 for transmitting a drive signal (frequency signal) from a drive circuit (not shown) to the piezoelectric element 4 is attached to the piezoelectric element 4.

  A spring receiving member 11 is fixed to the output shaft 14 by press fitting. The bearing member 16 supports the other end side of the output shaft 14. Further, a C-shaped ring 15 is attached to the output shaft 14 adjacent to the bearing member 16, and the output shaft 14 is prevented from moving in the longitudinal direction by the C-shaped ring 15. That is, the C-shaped ring 15 suppresses a load in the thrust direction applied to the output shaft 14 from the outside and fluctuations in the applied pressure by the spring 10 as will be described later.

  The rotor 7 and the rotor receiving member 9 are integrally formed by caulking. Here, a concave portion is formed on the surfaces of the rotor 7 and the spring receiving member 11 facing each other, and a spring 10 described later is accommodated in a space formed by the concave portion. In a state where the spring 10 is compressed in the rotation axis direction of the rotor 7, one end side is in contact with the bottom surface of the concave portion of the rotor 7, and the other end side is in contact with the bottom surface of the concave portion of the spring receiving member 11. Thus, the rotor 7 is brought into pressure contact with the elastic body 5 (slider 6) by receiving the urging force of the spring 10.

  With the storage structure of the spring 10 as described above, the spring 10 can be prevented from being tilted or displaced with respect to the output shaft 14. In addition, the vibration wave motor can be downsized (downsized in the direction of the rotation axis) as compared with the case where the concave portion is not formed in the rotor 7 and the spring receiving member 11.

  The protrusion 9a formed on the outer periphery of the rotor receiving member 9 is engaged with a recess 11a formed on the outer peripheral plane of the spring receiving member 11, and is displaced in the longitudinal direction of the output shaft 14 in the recess 11a. It is possible. Here, the protrusions 9a are provided at a plurality of positions in the circumferential direction of the rotor receiving member 9, and the spring receiving member 11 is provided with recesses 11a at positions that are in phase with the plurality of protrusions 9a. .

  By incorporating the plurality of protrusions 9a into the recess 11a in phase, the rotor receiving member 9 is coupled to the recess 11a regardless of the pressure applied by the spring 10, and the rotational force of the rotor 7 is applied to the spring receiving member 11 and It can be transmitted to the output shaft 14.

  In a space formed between the bearing member 16 and the housing 1, a rubber ring 8 that is in contact with the outer peripheral surface of the output shaft 14 is disposed. The rubber ring 8, the housing 1, and the outer cylinder 13 are formed. The space is sealed. And in this sealed space, the desiccant 18 is arrange | positioned and the moisture etc. in sealed space are removed. Thereby, it can prevent that the elastic body 5 and the rotor 7 adhere according to environmental changes, such as moisture.

  The reflective optical sensor module 17 is fixed to the outer cylinder 13, and an encoder 12 fixed to the spring receiving member 11 is provided at a position facing the optical sensor module 17. With this configuration, the optical sensor module 17 receives the reflected light from the encoder 12 and outputs a signal corresponding to the rotation of the spring receiving member 11 (rotor 7).

In the present embodiment, since the reflection type optical sensor module 17 is provided, the vibration wave motor can be reduced in size as compared with the case where a light projecting element and a light receiving element that receives light from the light projecting element are provided at positions facing each other. The size of the output shaft 14 in the longitudinal direction can be reduced.
In the structure of the vibration wave motor of the above-described embodiment, when alternating voltages having different phases are applied to the two-phase regions formed in the piezoelectric element 4, a progressive vibration wave is generated in the elastic body 5, The rotor 7 in pressure contact with the elastic body 5 rotates around the output shaft 14 by the traveling wave in the elastic body 5.

  The rotational force of the rotor 7 is transmitted to the output shaft 14 via the rotor receiving member 9 and the spring receiving member 11, and the output shaft 14 rotates. Here, the output shaft 14 is connected to the driven member 20 via a power transmission mechanism (not shown), and the driven member 20 operates by receiving a driving force from the output shaft 14. Examples of the driven member 20 include a lens driving member for driving a lens provided in a lens barrel, and a photosensitive drum and a camera provided in the image forming apparatus for rotating in a pan direction and a tilt direction. There are drive members.

  Next, the structure of the spring (biasing means) 10 in this embodiment will be described. 4A shows a top view of the spring 10 of this embodiment, and FIG. 4B shows a side view of the spring 10.

  The spring 10 has a structure in which a long member formed in a wave shape is wound around the output shaft 14, and both ends of the spring 10 (the A and B surfaces shown in FIG. 4B). Are formed in an uneven shape. Further, on both end faces of the spring 10, as shown in FIG. 4A, there are provided portions C that are corrugated peaks at three locations with substantially equal intervals in the circumferential direction of the spring 10. Further, the corrugated valleys are also provided at three positions at substantially equal intervals in the circumferential direction of the spring 10.

  Each of these three portions, which are peaks and valleys, is located in a plane perpendicular to the longitudinal direction of the output shaft 14.

  Portions C that are three crests on both end faces of the spring 10 come into contact with the rotor 7 and the rotor receiving member 11. As described above, the spring 10 abuts against the rotor 7 and the rotor receiving member 11 at three equally spaced regions in the circumferential direction, thereby applying a uniform pressure to the rotor 7 and the rotor receiving member 11. be able to.

  In this embodiment, the spring 10 is in contact with the rotor 7 or the like in three regions, but at least three or more contact regions are provided (particularly, a plurality of equidistant intervals in the circumferential direction of the spring 10). If it is provided at a position), a uniform pressure can be applied to the rotor 7 and the like.

  Further, as shown in FIG. 4B, in the intermediate layer D of the spring 10, adjacent to each other in the longitudinal direction of the output shaft 14, the region including the waveform inflection point (in FIG. Area and a valley area) are in contact with each other.

  On the other hand, the cross-sectional shape of the linear member constituting the spring 10 is formed such that the length of the spring 10 in the radial direction is longer than the length of the output shaft 14 in the longitudinal direction, as shown in FIG. As a cross-sectional shape of the linear member, for example, a rectangular shape or an elliptical shape can be used.

  In the structure of the spring 10 described above, when the traveling wave generated in the elastic body 5 is transmitted to the rotor 7, the spring 10 has the both end surfaces (regions that form three peaks), the rotor 7, and the rotor receiving member 11. In addition, sliding friction occurs between the two members, and linear friction between the linear members (the above-described region serving as a mountain and the region serving as a valley) occurs in the intermediate layer D of the spring 10.

  As described above, sliding friction is generated in a plurality of contact regions in the spring 10, whereby vibration in the rotor 7 is converted into thermal energy, and unnecessary vibration and abnormal vibration generated in the rotor 7 can be absorbed.

  A phenomenon similar to this is also observed in the leaf spring structure shown in FIG. 3, and when a plate-like rubber ring 205 is attached to the leaf spring 201 and a traveling wave is transmitted to the elastic body, the intermolecular molecules constituting the rubber The spring 10 can have the same characteristic as that of absorbing the unnecessary vibration.

  Here, in the conventional vibration wave motor using the coil spring 101 shown in FIG. 2, the coil spring 101 is formed in a spiral shape and applies pressure to the rotor 102. In the structure of this coil spring 101, since there are few contact parts which produce sliding friction compared with the spring 10 in a present Example, there is little conversion of thermal energy and it cannot fully absorb unnecessary vibration. Moreover, as described above, the coil spring 101 cannot apply a uniform pressure to the rotor 102, and so-called squealing occurs.

  In the spring 10 of this embodiment, since the uniform pressure can be applied to the rotor 7 as described above, the wear of the slider 6 caused by the rotation unevenness of the rotor 7 can be reduced.

  Also, if the spring constant of the spring 10 is set lower than the spring constant of the conventional leaf spring, a predetermined pressure can be easily applied to the rotor 7, and the conventional vibration wave motor using the leaf spring can be applied. Thus, there is no need to provide a pressure adjusting mechanism. Thus, by eliminating the need for the pressure adjusting mechanism, the vibration wave motor can be reduced in size and cost.

It is sectional drawing of the vibration wave motor which is Example 1 of this invention. It is sectional drawing of the conventional vibration wave motor using a coil spring. It is sectional drawing of the conventional vibration wave motor using a leaf | plate spring. It is the upper side figure (A) and side view (B) of the spring in Example 1. FIG.

Explanation of symbols

1: Housing 2: Bearing member 3: Flexible printed circuit board 4: Piezoelectric element 5: Stator 6: Slider 7: Rotor 8: Rubber ring 9: Rotor receiving member 10: Scroll wave spring 11: Spring receiving member 12: Encoder 13: Outside Tube 14: Output shaft 15: C-shaped ring 16: Bearing member 17: Optical sensor module

Claims (1)

A vibrating body having at least an electro-mechanical energy conversion element and exciting vibrations by applying a frequency signal to the electro-mechanical energy conversion element, a contact body in contact with the vibrating body, and the contact body as the vibrating body And a biasing means for biasing
A vibration type actuator that relatively rotates the vibrating body and the contact body around a specific axis by vibration excited by the vibrating body,
The biasing means is formed by multiple windings of elongated members alternately having peaks and valleys around the specific axis, and at least three peaks or valleys are the specific A vibration type actuator, wherein the vibration type actuator is located in a plane orthogonal to an axis, and the peak portion and the valley portion are in contact with each other in the specific axial direction.

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