JP6257281B2 - Ultrasonic actuator - Google Patents

Description

The present invention relates to an ultrasonic actuator including an ultrasonic motor applied to a digital camera or the like, and more particularly to an ultrasonic actuator including a linear ultrasonic motor, for example.

Conventionally, in an ultrasonic actuator including this type of linear ultrasonic motor, a vibrating member (vibrator) that periodically vibrates by application of a high-frequency voltage is pressed against a sliding member to generate a frictional force therebetween. A technique for driving a sliding member is known. Patent Document 1 discloses the following technique. This is an ultrasonic motor including a vibrating member that periodically vibrates by application of a high-frequency voltage and a moving member that is moved in accordance with the periodic vibration of the vibrating member. The vibration member is supported only by a spring member that applies a pressing force to press the vibration member and the moving member, and the support position of the vibration member by the spring member is configured to be at a vibration node of the vibration member. Yes.

Japanese Patent Laid-Open No. 2001-292584

However, in the prior art disclosed in Patent Document 1 described above, the function of supporting the vibration node of the vibrating body (vibrator) and the pressurization of the vibrating body to generate a frictional force on the vibrating body and the rail (sliding member). The function is performed using one spring member and a plurality of rubber sheets. The spring member is incorporated between the fixed plate and the vibrating body via a rubber sheet. Thus, the vibrator is pressed against the rail, and the rail is frictionally driven by the ultrasonic vibration of the vibrating body. At this time, a roller is disposed on the surface of the rail opposite to the surface on which the vibrating body is located, and the rail is movably supported by reducing sliding resistance. As described above, the structure for generating the pressure contact force is closed between the fixed plate and the roller by sandwiching the rail between the vibrating body and the roller.

When the structure described above is defined as a housing, which is composed of a fixed plate, a rubber sheet, a spring member, a vibrator, and a roller and sandwiches the rail in a movable manner, the position of the housing is the pressurizing part of the vibrator. Is defined by the position pressed against the rail by the pressing force of the leaf spring. In such a state, for example, when the rail is fixed and the housing is driven, if the high-speed reciprocating movement is performed, the housing moves integrally with the vibrator under the influence of the speed change due to sudden deceleration and sudden acceleration movement. Generates a rotational force in the pitching direction relative to the moving direction. This is a phenomenon that occurs when there is a difference in height between the center of gravity of the housing and the driving force generating portion. By this rotational force, one of the two rollers receives a force in a direction away from the rail. If this force exceeds the pressure applied by the leaf spring, the roller will float near the reciprocating point of the reciprocating motion, and noise will be generated due to repeated separation and contact between the roller and the rail during reciprocating driving. To do. This occurs, for example, when performing a so-called wobbling operation in which a focusing operation is performed based on the contrast information of a subject while driving a focusing lens in a minute amount and back and forth in the optical axis direction in a focusing operation of an optical device. . As a result, unnecessary noise may be recorded in the recorded voice.

In view of the above problems, an ultrasonic actuator according to the present invention includes a vibrator that is ultrasonically vibrated by an applied drive voltage, a relative sliding member that is pressed against each other and relatively moved, and A support member that holds the driven part, which is a vibrator or the relative sliding member, so as to be movable back and forth; a guide part that guides the support member in a moving direction of the driven part; and And a pressurizing part that presses the sliding member against each other. And the control member which controls the movement which the said supporting member tries to move to the pressurization direction of the said to-be-driven part is provided. The guide portion includes a first guide portion and a second guide portion, and the first guide portion is a groove portion formed in the support member, a first rolling member, and a position facing the groove portion. An intermediate member having a groove portion formed on the second guide portion, and the second guide portion includes a second rolling member, and a pressing holding member that presses and holds the second rolling member against the intermediate member. The press holding member is fixed to the support member so as to sandwich the second rolling member with the intermediate member.

According to the present invention, it is possible to realize an ultrasonic actuator capable of driving a focusing lens with high noise reduction by reducing unnecessary noise in a wobbling operation or the like during moving image shooting.

The cross-sectional view of the ultrasonic actuator used as a focus drive source or the like. The longitudinal cross-sectional view of the ultrasonic actuator utilized as a focus drive source. Sectional drawing of an example of the lens-barrel incorporating the ultrasonic actuator of this invention. The longitudinal cross-sectional view for demonstrating the structure of a comparative example.

In the present invention, the guide member that guides the vibrator or the support member that is driven relative to the vibrator and that is a relative sliding member that moves relative to the vibrator and that moves relative to the vibrator in the moving direction. On the other hand, a regulating member that regulates the movement of the supporting member in the driven portion pressurizing direction is provided. More specifically, in order to reduce noise during high-speed reciprocating operation, the driven part support member is lifted from the V-groove part which is the guide part by an external force or inertial force greater than the pressure reaction force of the driven part. Is suppressed by a regulating member.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
Example 1
FIG. 1 shows an embodiment of the present invention, and is a cross-sectional view of a main part of an ultrasonic actuator including a linear ultrasonic motor used as a focus drive source for an optical device (cross-sectional view perpendicular to the drive direction). It is a longitudinal cross-sectional view (drive direction sectional view).

In the figure, 101 is a vibrator that vibrates ultrasonically by an applied drive voltage, and the joined portion 101a is fixed to the joining portion 102a of the connecting member 102 by welding or the like (see FIG. 2). Further, the piezoelectric element 103 is fixed to the vibrator 101 with a known adhesive or the like. The piezoelectric element 103 is set so that when a high frequency voltage is applied, the vibrator 101 resonates in the longitudinal direction and the lateral direction, respectively. As a result, as shown in FIG. 2, the tip of the pressure contact portion 101b formed on the vibrator 101 causes an elliptical motion. By changing the frequency and phase of the high-frequency voltage applied to the piezoelectric element, a desired movement can be generated by appropriately changing the rotation direction and the ellipticity ratio. Therefore, a driving force is generated by a frictional force with the slider (104 in FIG. 1) which is a relative sliding member which is a counterpart component. In this embodiment, the vibrator itself is moved in the optical axis direction (in FIG. 1). It is possible to advance and retreat along the direction perpendicular to the plane of the drawing (left and right direction in FIG. 2). A configuration in which the slider 104 can be advanced and retracted while fixing the vibrator side can also be employed.

In FIG. 1, reference numeral 105 denotes a vibrator support member, and the screwing portion 102 b of the connecting member 102 to which the vibrator 101 is fixed is fixed to the attachment position by a screw 106. A pressure plate 107 is configured to press and hold the piezoelectric element 103 with an elastic member 108 interposed therebetween as will be described later. Reference numeral 111 denotes a pressurizing spring that is a pressurizing unit, and generates a pressing force that presses the vibrator 101 against the slider 104 in the assembled state. Reference numeral 113 denotes a moving plate that constitutes a part of a guide portion that is fixed to the contact portion 105a of the vibrator support member 105 by a known method such as adhesion or screwing. The moving plate 113 may be formed integrally with the vibrator support member 105. The moving plate is formed with a plurality of V-groove portions 113a into which balls 114 as rolling members are fitted to guide the vibrator support member 105 in the optical axis direction (drive direction). That is, here, the V-groove portion of the support member is formed on a moving plate that is a separate part fixed to the main body portion of the support member. As a configuration of the guide portion, for example, the moving plate is a leaf spring member, and a curved portion thereof or the like slides on a flat surface of a cover plate described later or a rolling member in the V groove portion to drive the vibrator support member 105. It may be configured to guide in the direction.

Reference numeral 115 denotes a cover plate that is an intermediate member, and is fixed to the unit support member 116 with a known screw or the like. The cover plate 115 also constitutes a part of the above-described guide portion. By holding the ball 114, which is the first rolling member, by the V groove 115a provided at a position facing the V groove 113a of the moving plate 113, the vibrator support member 105 can be advanced and retracted along the driving direction. It is possible to support. A plurality of V-groove portions 115c are further formed in the cover plate. As described above, the present embodiment includes the following configuration of the guide portion. That is, the guide part includes a first guide part and a second guide part. The first guide portion includes a V-groove portion formed in the support member, a first rolling member, and an intermediate member having a V-groove portion formed at a position facing the V-groove portion. The second guide portion includes a second rolling member described later and a pressing holding member which is a clamping plate described later that presses and holds the second rolling member against the intermediate member. The second rolling member is fixed to the support member so as to be sandwiched between the intermediate member.

Reference numeral 150 denotes a sandwiching plate, and an outer shape is formed on the sandwiching plate so that a flat surface portion is located at a portion opposed to the V groove 115c formed in the cover plate 115. Then, the clamping plate 150 is fastened to the vibrator support member 105 with a screw through a screw hole (not shown) at the time of assembly. At this time, there is a gap between the V groove 115c on the cover plate and the clamping plate. A plurality of balls 152 that are second rolling members are sandwiched. Therefore, each dimension is appropriately set so that the cover plate 115 can be sandwiched between the moving plate 113 and the sandwiching plate 150 via the balls 114 and 152 without play. A part 150c of the sandwiching plate 150 is elastically deformed and constitutes a regulating member. That is, here, the pressing holding member and the second rolling member also serve as a regulating member. The part 150c is a leaf spring member, and a curved portion or the like of the portion 150c slides on a rolling member in the upper flat surface of the cover plate 115 or the V-groove to guide the vibrator support member 105 in the driving direction. It may be a simple configuration. Moreover, it is good also as a structure where the V-groove part is formed in the press holding member, and the 2nd rolling member is inserted in this. As described above, the second rolling member is sandwiched between the V-groove portion or the flat portion formed in the intermediate member and the flat portion or the V-groove portion formed in the press holding member.

Further, at this time, the moving plate 113 is configured to be movable in the driving direction (the direction perpendicular to the paper surface in FIG. 1) with respect to the cover plate 115 by the above-described ball rolling function. The slider 104 is fixed to the unit support member 116 with a screw or the like. With the configuration so far, the ultrasonic actuator including the linear ultrasonic motor according to the present embodiment is completed.

In this embodiment, the driven part is the vibrator, the support member is a vibrator support member that holds the vibrator, and the regulating member tries to move the vibrator support member in the pressurizing direction of the vibrator. The movement is regulated. That is, in this embodiment, the structure on the side of the piezoelectric element 103 and the vibrator 101 moves. However, as described above, if this structure is fixed, the slider 104 can be moved as it is. Can do.

FIG. 4 is a schematic configuration diagram for explaining the structure of a comparative example having no regulating member. In FIG. 4, the same reference numerals as those in FIG. 1 and FIG. The pressure spring 111 presses the vibrator 101 to which the piezoelectric element 103 is fixed to the slider 104 via the pressure plate 107 and the elastic member 108.

As a result, a driving force is generated at the press-contact portion between the vibrator and the slider, and it can move in the driving direction under the force of F. At this time, the pressure spring 111, the pressure plate 107, the elastic member 108, the piezoelectric element 103, the vibrator 101, the coupling member 102, the vibrator support member 105, and the moving plate 113 are integrated with the vibrator in the driving direction. Move along. In the focusing operation of the optical apparatus as described above, for example, it is assumed that a so-called wobbling operation is performed in which a focusing operation is performed based on the contrast information of the subject while driving the focusing lens in a minute amount and back and forth in the optical axis direction. At this time, the position of the contact portion between the vibrator 101 and the slider 104 (a portion where F is generated in FIG. 4), which is a driving force generating portion, and the center of gravity G of the driving portion that moves together with the vibrator (see FIG. 4), a rotational force P in the pitching direction is generated with respect to the moving direction. When the force exceeds the reaction force of the above-described applied pressure, the vibrator support member 105 rotates and moves in the pitching direction. At this time, a gap is generated between the V groove formed in the moving plate 113 and the cover plate 115 and the ball 114. As a result, the continuous driving of the wobbling generates a continuous collision sound between the V-groove part and the ball, and the silentness required for photographing is impaired.

However, according to the pressurizing mechanism and the rolling support structure of the vibrator holding member 105 of the embodiment shown in FIG. 1, the moving plate 11 13 is fixed to the vibrator support member 105 as described above. The pressure spring 111 presses the vibrator 101 on which the piezoelectric element 103 is fixed to the slider 104 via the pressure plate 107 and the elastic member 108. The pressure reaction force at this time generates a force that presses the moving plate 113 upward in FIG. 1 via the vibrator support member 105. At this time, the ball 114 is disposed between the V groove 113a formed on the moving plate 113 and the V groove 115a formed on the cover plate 115 and is held by the pressing force. Further, according to the rolling support structure of the above embodiment, the V-groove portion 115c is formed on the upper surface side of the cover plate 115, and the sandwiching plate 150 is sandwiched between the ball 152 and the vibrator support member 105 by screws or the like (not shown). Fixed. As a result, the moving plate 113 holds the cover plate 115 between the holding plate 150 and the balls 114 and 152. At this time, for example, the sandwiching plate 150 is made of an elastic member, and its height dimension (H in FIG. 1) is set so that a part 150c thereof is elastically deformed at the time of screwing or the like. ing. As a result, the movable plate 113 and the sandwiching plate 150 can sandwich the cover plate 115 without play due to the elastic force of the sandwiching plate 150 that is a restricting member. Therefore, even if a force in the pitching direction is applied to the vibrator support member 105 in the driving by the above-described wobbling operation or the like, the driven portion (in the above embodiment, the optimum force is applied to the V-groove portion regardless of the above-mentioned pressing force. The vibrator support member 105) can be held. Therefore, it is possible to achieve noise reduction during shooting.

As described above, specific examples of the ultrasonic actuator including the ultrasonic motor according to the present invention have been described in detail. However, the present invention is not limited to the above-described embodiments, and may be as long as it is shown in the claims. Any form is possible.

(Example 2)
FIG. 3 shows a cross-sectional view of a second embodiment relating to a lens barrel incorporating the ultrasonic motor unit (ultrasonic actuator) 100 of the present invention. In the present embodiment, the lens barrel is described as an interchangeable lens that can be exchanged for the camera body. Since the lens barrel is substantially rotationally symmetric around the optical axis, only the upper half is displayed.

An interchangeable lens 2 is detachably attached to the camera body 1, and an image sensor 1 a is provided in the camera body 1. The mount 11 has a bayonet portion for attaching the interchangeable lens 2 to the camera body 1. The fixed cylinder 12 is in contact with the flange portion of the mount 11 and fixes the mount 11 with screws (not shown). A fixed barrel 12 is fixed with a front barrel 13 holding the fixed lens G1 and a rear barrel 14 holding the fixed lens G3. Reference numeral 15 denotes a focus lens holding frame that holds the focus lens G <b> 2, and is held by a known guide bar 16 held by the front lens barrel 13 and the rear lens barrel 14 so as to be linearly movable. A flange portion (not shown) is formed on the ground plate 161 in the ultrasonic motor unit 100 and is fixed to the rear lens barrel 14 with screws.

When the driven portion 162 of the ultrasonic motor unit 100 is driven with the above configuration, the driving force of the ultrasonic motor unit 100 is transmitted to the focus lens holding frame 15 via the driving force transmitting portion 163. . The focus lens holding frame 15 moves linearly along the guide bar 16 described above. Thus, the lens holding frame 15 is driven by the driving force of the ultrasonic actuator of the present invention.

101: vibrator (driven part), 103: piezoelectric element, 104: slider (relative sliding member, driven part), 105: vibrator support member, 111: pressure spring (pressure part), 113: movement Plate (guide portion), 113a, 115a, 115c: V groove portion (guide portion), 114: ball (guide portion), 115: cover plate (guide portion), 150: sandwiching plate (regulating member), 152: ball (regulating) Element),

Claims (7)

A vibrator that vibrates ultrasonically by an applied drive voltage;
A relative sliding member that is in pressure contact with the vibrator and relatively moves;
A support member that holds the driven portion, which is the vibrator or the relative sliding member, so as to freely advance and retract ;
A guide portion that guides the support member in the moving direction of the driven portion;
A pressurizing part that presses the vibrator and the relative sliding member together by pressurization ;
Includes a restricting member before Symbol support member to restrict the movement going to move to the pressing direction of said driven portion,
The guide part includes a first guide part and a second guide part,
The first guide portion includes a groove portion formed in the support member, a first rolling member, and an intermediate member having a groove portion formed at a position facing the groove portion,
The second guide portion includes a second rolling member and a pressing holding member that presses and holds the second rolling member against the intermediate member,
The ultrasonic actuator , wherein the pressing holding member is fixed to the support member so as to sandwich the second rolling member with the intermediate member . The ultrasonic actuator according to claim 1 ,
The ultrasonic actuator, wherein the pressing holding member and the second rolling member also serve as the regulating member. The ultrasonic actuator according to claim 1 or 2 ,
The ultrasonic actuator, wherein the second rolling member is sandwiched between a groove portion or a flat portion formed in the intermediate member and a flat portion or a groove portion formed in the press holding member. The ultrasonic actuator according to any one of claims 1 to 3 ,
The ultrasonic actuator according to claim 1, wherein the groove portion of the support member is formed in a separate part fixed to the main body portion of the support member. The ultrasonic actuator according to any one of claims 1 to 4 ,
The driven part is the vibrator;
The support member is a vibrator support member for holding the vibrator;
The ultrasonic actuator according to claim 1, wherein the restricting member restricts movement of the vibrator support member in the pressurizing direction of the vibrator. A vibrator that vibrates ultrasonically by an applied drive voltage;
A relative sliding member that is in pressure contact with the vibrator and relatively moves;
A support member that holds the driven portion, which is the vibrator or the relative sliding member, so as to freely advance and retract;
A guide portion that guides the support member in the moving direction of the driven portion;
A pressurizing part that presses the vibrator and the relative sliding member together by pressurization;
A regulating member that regulates the movement of the support member to move in the pressure direction of the driven part;
The guide portion includes a cover member, and a ball member that is in pressure contact with the cover member by the force of the pressure portion,
The ultrasonic actuator according to claim 1, wherein the regulating member is disposed at a position farther from the cover member with respect to a contact surface between the vibrator and the relative sliding member in the pressurizing direction. A lens barrel, wherein the lens holding frame is driven by the driving force of the ultrasonic actuator according to any one of claims 1 to 6.