JP4745754B2 - Piezoelectric vibrator, ultrasonic motor using the same, and electronic equipment - Google Patents

Description

  The present invention relates to a piezoelectric vibrator that functions by vibration of a vibrating body having a piezoelectric element and an electronic device using the same, and more particularly to add a driving signal from a driving circuit to a piezoelectric element or obtain a signal from a piezoelectric element. It relates to a conductive structure.

  So-called piezoelectric vibrators are used in various piezoelectric devices as sensors such as acceleration and angular velocity, oscillators, filters, transformers, and actuators.

  Among them, for example, an ultrasonic motor that uses vibration and frictional force due to resonance of a vibrating body is characterized by being small and capable of obtaining high torque, and is therefore used for camera autofocus drive, wristwatch calendar feed drive, etc. ing.

  The vibration of the vibrating body is generated by applying a driving signal from a driving circuit to a piezoelectric element provided in the vibrating body through a conductive structure such as a lead wire, but particularly when the ultrasonic motor is downsized. Since a conducting structure such as a lead wire has a high risk of suppressing vibration of the vibrating body, a conducting structure with less vibration loss considering fluctuations in the manufacturing process is required.

As an example of this conduction structure, the one shown in FIG. 6 is used. In FIG. 6, the vibrating body 122 is fixed via a central shaft 132. A lead substrate 136 is fixed to the support member 124, and the conductive pattern provided on the lead substrate 136 is bent so that the end of the conductive pattern is in contact with the piezoelectric element 802 and the end of the conductive pattern is bonded to the piezoelectric element 802. Is done.
Japanese Patent Laid-Open No. 11-215865 (FIG. 1)

  However, in the conventional structure, the vibration of the vibrating body leaks through the conduction pattern, which may cause energy loss and decrease the output of the ultrasonic motor. In particular, tension may act between the two joints of the conductive pattern due to variations in the bonding position of the lead substrate to the support member and variations in the bonding position of the conductive pattern to the piezoelectric element that occur during manufacturing. At the same time, the tension itself may vary.

  The higher the tension, the easier it is to transmit high-frequency vibrations, that is, vibrations of the vibrating body. Therefore, the degree of vibration leakage and vibration leakage varies, causing a decrease in the output of the ultrasonic motor and individual differences in output. There was a fear. Since this tension also fluctuates due to environmental changes due to temperature or the like, the output of the ultrasonic motor may fluctuate greatly depending on the external environment.

  In addition, due to the large rigidity of the joint portion of the conductive pattern to the piezoelectric element, a non-uniform portion is formed in the vibration mode of the vibrating body, which may cause a decrease in output characteristics and variations in individual ultrasonic motors.

  When a large vibration or impact is applied to the ultrasonic motor, there is a possibility that the joint between the conductive pattern and the piezoelectric element may be peeled off.

  Similarly, in other piezoelectric devices, there is a risk of performance variation and a decrease in reliability.

  Therefore, in order to solve the above-described problems, in the ultrasonic motor of the present invention, in a vibrating body having a piezoelectric element, a conduction pattern for supplying a driving signal to the piezoelectric element, and an ultrasonic motor frictionally driven by vibration of the vibrating body The conduction pattern has a structure having a buffer portion having a shape protruding from a straight line connecting a joint portion between the piezoelectric element and the conduction pattern and a fixed end to which the conduction pattern and the conduction pattern are fixed. Here, it is assumed that the fixed end is provided on a support plate for fixing the vibrating body.

  Here, the buffer portion is formed before the piezoelectric element and the conduction pattern are joined, or before the conduction pattern and the fixing portion are joined.

  The buffer portion has a structure protruding in the in-plane direction of the conductive pattern. Or it is set as the structure which protrudes in the thickness direction of a conduction pattern.

  Moreover, the junction part with the piezoelectric element of a conduction pattern is made into the shape extended in the circumferential direction of the piezoelectric element.

  And it is set as the electronic device characterized by having the operation part driven by these ultrasonic motors.

  According to the present invention, even if the piezoelectric vibrator used in the piezoelectric device such as an ultrasonic motor is downsized, the energy loss in the conductive structure is small, a large output can be obtained, and the output characteristics of each piezoelectric vibrator can be obtained. Variation can be made extremely small. In addition, since a lead substrate is used without using a lead wire, a piezoelectric vibrator excellent in mass productivity can be realized. In addition, since the conductive pattern is hardly affected by the tension due to temperature, impact, etc., a piezoelectric vibrator having excellent environmental resistance and reliability can be realized.

(Embodiment 1)
An application example to an ultrasonic motor will be described as a piezoelectric device using the piezoelectric vibrator of the present invention.

  The principle of the ultrasonic motor 130 will be briefly described based on the conventional example (FIG. 6).

  The elastic body 122b on the disk is provided with a protrusion 817 to constitute the vibrating body 122. The inner periphery of the piezoelectric element 802 is guided by a convex portion 122 d provided at the center of the vibrating body 122 and bonded to the vibrating body 122. The vibrating body 122 is supported by fixing the inner peripheral portion of the vibrating body 122. A moving body 134 composed of a guide member 134e having a pivot and a bearing at the center and a friction member 134c is rotatably guided by a center shaft 132 fixed to the support member 124. By pressing the pivot of the guide member 134e with the pressurizing spring 138, a frictional force acts between the protrusion 817 of the vibrating body 122 and the friction member 134c of the moving body 134. A conductive pattern 136a is provided on the lead substrate 136, and an end portion of the conductive pattern is bonded to the piezoelectric element 802. The lead substrate 136 is fixed to the support member 124.

  A piezoelectric body according to the present invention includes a vibrating body having a piezoelectric element, a structure supporting a vibrating body, a structure having a lead structure in which one end is joined to the piezoelectric element and the other part is fixed to another member. And The vibrating body may be composed of only a piezoelectric element.

  When a drive signal is applied to the piezoelectric element 802 through the conduction pattern 136a, the vibrating body 122 excites vibrations in a predetermined vibration mode. The moving body 134 receives the displacement of the vibration of the vibrating body 122 via a frictional force and rotates. It should be noted that the conducting structure of the present invention is not used for the principle and structure shown in the conventional example (FIG. 6), but can be applied to other principles and structures.

  Since the present invention relates to a conduction structure of an ultrasonic motor, an embodiment of the present invention will be described below based on the drawings with a focus on differences from the conventional example.

  FIGS. 1A and 1B are views of the configuration of the ultrasonic motor of the present invention as viewed from the front and the back, respectively. Here, the front and back are views seen in the directions of arrows A and B in FIG. 6 (cross-sectional view of an ultrasonic motor) showing a conventional example.

In FIG. 1B, a piezoelectric element 5 is bonded to the vibrating body 4 supported by the support member 1 via a center axis (not shown). Electrodes 6a and 6b are deposited on the piezoelectric element 5. A lead substrate 2 made of polyimide and copper foil is bonded to the support member 1. The lead substrate 2 is provided with a conduction pattern 3 to be joined to the piezoelectric element 5, and a joint portion 3 b of the conduction pattern 3 is joined to the electrode 6 deposited on the piezoelectric element 5. Here, the conductive pattern 3 includes a buffer portion 3a having a shape protruding from a straight line connecting the joining portion 3b of the piezoelectric element 5 and the conductive pattern 3 and the fixed end 3c to which the conductive pattern 3 is fixed. the has.

  Next, details of the lead substrate 2 and the conductive pattern 3 and a bonding method to the piezoelectric element 5 will be described.

FIG. 2A shows the lead substrate 2 having the conductive pattern 3. Here, the buffer portion 3 a has a curved shape having a portion protruding in the in-plane direction of the lead substrate 2. Here, the shape of the buffer portion 3a is not limited to that shown in the present embodiment, and any shape that reduces the spring multiplier of the conductive pattern 3 may be used. Accordingly, the shape and number of the curved portions are not limited. Since the buffer portion 3a has a structure protruding in the in-plane direction of the lead substrate 2, that is, the conductive pattern 3, it can be manufactured together with the lead substrate 2 by etching, pressing, or the like, so that manufacturing is simplified and manufacturing variation can be reduced. .

  As shown in FIG. 2B, the lead substrate 2 is first fixed to the support plate 1 by adhesion or the like. Thereafter, the joint portion 3b is joined to the piezoelectric element 5 and the structure shown in FIG. 1 is obtained. However, the positional deviation when the lead substrate 2 and the support plate 1 are fixed and the position when the joint portion 3b is joined to the piezoelectric element 5 are obtained. Residual stress on the conductive pattern 3 caused by such variations is absorbed by the buffer portion 3a. This effect is the same even when the step of fixing the lead substrate 2 to the support plate 1 after the bonding portion 3b is bonded to the piezoelectric element 5 is taken.

  The lead structure of the present invention can also be applied to other piezoelectric devices. That is, the piezoelectric vibrator in the piezoelectric device comprises a vibrating body having a piezoelectric element, a member supporting the vibrating body, and a structure having a lead structure in which one end is joined to the piezoelectric element and the other part is fixed to another member. As long as it is applied, the piezoelectric device of any function may be applied. In addition, if the piezoelectric device is a piezoelectric device that functions by obtaining signals from a piezoelectric vibrator such as a sensor, filter, or transformer, the conduction pattern constituting the lead structure may transmit a signal output from the piezoelectric element. I do not care.

(Embodiment 2)
Another embodiment of the conduction structure of the present invention will be described with reference to the drawings. Here, only differences from the first embodiment and the conventional example will be described.

FIG. 3A is a view of the ultrasonic motor of the present invention viewed from the back side (the direction of arrow B in FIG. 6). FIG. 3B is a side sectional view. In the present embodiment, the buffer portion 7a is characterized by protruding in the thickness direction of the conductive pattern 7, that is, in the direction orthogonal to the protruding direction of the buffer portion 3a of the first embodiment. In this case, after the lead substrate having the linear conductive pattern is manufactured as in the conventional example, the buffer portion 7a is formed by bending or the like. Thereafter, the lead substrate 2 and the support member 1 are joined, and the joining portion 7b of the conductive pattern 7 and the piezoelectric element 5 are joined.
The lead structure of the present invention can also be applied to other piezoelectric devices. That is, the piezoelectric vibrator in the piezoelectric device includes a vibrating body having a piezoelectric element, a member supporting the vibrating body, a structure having a lead structure in which one end is joined to the piezoelectric element and the other part is fixed to another member. As long as it is applied, the piezoelectric device of any function may be applied. In addition, if the piezoelectric device is a piezoelectric device that functions by obtaining signals from a piezoelectric vibrator such as a sensor, filter, or transformer, the conduction pattern constituting the lead structure may transmit a signal output from the piezoelectric element. I do not care.

(Embodiment 3)
Another embodiment of the conduction structure of the present invention will be described with reference to the drawings. Here, only differences from the first and second embodiments and the conventional example will be described.

  FIG. 4 is a view of the ultrasonic motor of the present invention viewed from the back side (in the direction of arrow B in FIG. 6).

In the present embodiment, the joint portion 8 a of the conductive pattern 8 with the piezoelectric element 5 has a shape extending in the circumferential direction of the piezoelectric element 5. In particular, the joining position of the joining portion 8a to the piezoelectric element 5 is located at a nodal circle of the vibration mode generated by the vibrating body 4. Accordingly, it is possible to extremely reduce the influence of the rigidity of the joining portion 8a and the solder used for joining on the vibration mode excited by the vibrating body 4. Even in the vibration mode having no nodal circle, the displacement of vibration varies depending on the radial position, and therefore, the excitation force of the piezoelectric element 5 does not need to be suppressed by adopting the joining method of the present embodiment.
The lead structure of the present invention can also be applied to other piezoelectric devices. That is, the piezoelectric vibrator in the piezoelectric device comprises a vibrating body having a piezoelectric element, a member supporting the vibrating body, and a structure having a lead structure in which one end is joined to the piezoelectric element and the other part is fixed to another member. As long as it is applied, the piezoelectric device of any function may be applied. In addition, if the piezoelectric device is a piezoelectric device that functions by obtaining signals from a piezoelectric vibrator such as a sensor, filter, or transformer, the conduction pattern constituting the lead structure may transmit a signal output from the piezoelectric element. I do not care.
(Embodiment 4)
An example in which an electronic apparatus is configured using the ultrasonic motor 100 using the piezoelectric vibrator of the present invention will be described with reference to FIG.

  FIG. 5 shows a block diagram in which the ultrasonic motor 100 of the present invention is applied to a drive source of an electronic device, and a moving body 101 that is frictionally driven by a vibrating body 4 joined to a piezoelectric element 5 and a moving body. A transmission mechanism 110 that operates integrally with the body 101, and an output mechanism 111 that operates based on the operation of the transmission mechanism 110. Here, an example in which the moving body 101 is a rotating body and the moving body 101 is rotated will be described.

  Here, the transmission mechanism 110 uses a transmission wheel such as a gear train or a friction wheel. The output mechanism 110 serving as an operating unit includes a paper feed mechanism in a printer, a shutter drive mechanism, a lens drive mechanism, a film winding mechanism in a camera, a pointer in an electronic device and a measuring instrument, and an arm in a robot. In the mechanism and machine tool, a tooth feeding mechanism, a processing member feeding mechanism, and the like are used.

  Note that an electronic timepiece, a measuring instrument, a camera, a printer, a printing machine, a robot, a machine tool, a game machine, an optical information device, a medical device, a moving device, and the like can be realized as the electronic device in this embodiment. Furthermore, if the moving body 7 is provided with an output shaft and has a power transmission mechanism for transmitting torque from the output shaft, an ultrasonic motor driving device can be realized.

    The piezoelectric vibrator of the present invention is particularly effective when it is miniaturized, and an ultrasonic motor that is a piezoelectric device using the piezoelectric vibrator is used for reading in an information recording device, driving a writing head, a lens of a digital camera, a video camera, etc. It can be applied as a driving source for various electronic devices such as driving. The sensor is used for camera shake detection, automobile movement position detection, impact force detection for HDDs, etc., the transformer is used as a boosting power source for the backlight of a personal computer, and the filter is used as signal processing in a communication device such as a mobile phone.

It is a figure which shows the structure of the ultrasonic motor of this invention. It is a figure which shows the manufacturing method of the ultrasonic motor of this invention. It is a figure which shows the structure of the ultrasonic motor of Embodiment 2 of this invention. It is a figure which shows the conduction | electrical_connection structure of the ultrasonic motor of Embodiment 3 of this invention. It is a block diagram of the electronic device which applied the ultrasonic motor using the piezoelectric element of this invention. It is a figure which shows the structure of the conventional ultrasonic motor.

Explanation of symbols

Piezoelectric element 5,802
Electrode 6
Vibrating body 4, 122
Mobile body 101, 134
Lead board 2, 136
Conductive pattern 3, 7

Claims (9)

A vibrating body having a piezoelectric element;
In a piezoelectric vibrator comprising a conduction pattern for supplying a drive signal to the piezoelectric element,
The conductive pattern protrudes from the straight line portion on a straight line connecting a joint portion between the piezoelectric element and the conductive pattern, the conductive pattern and a fixed end to which the conductive pattern is fixed, and the straight line portion . A piezoelectric vibrator having a buffer portion having a shape. 2. The piezoelectric vibrator according to claim 1, wherein the straight portion includes a straight portion that connects the joint portion and the buffer portion, and a straight portion that connects the fixed end and the buffer portion. 3. The piezoelectric vibration according to claim 1, wherein the buffer portion is formed before the piezoelectric element and the conductive pattern are bonded, or before the conductive pattern and the fixed end are bonded. Child. The piezoelectric vibrator according to claim 1 or 2, wherein the buffer unit is characterized in that protrudes in the in-plane direction of the conductive pattern. The piezoelectric vibrator according to claim 1 or 2, wherein the buffer unit is characterized in that protrudes in the thickness direction of the conductive pattern. The piezoelectric vibrator according to claim 1, wherein the fixed end is provided on a support plate that fixes the vibrating body . A vibrating body having a piezoelectric element;
  A piezoelectric vibrator comprising a conduction pattern for supplying a drive signal to the piezoelectric element;
  The piezoelectric vibrator according to claim 1, wherein a joint portion of the conduction pattern with the piezoelectric element is a nodal position of vibration excited by the vibrating body and has a shape extending in a circumferential direction of the piezoelectric element. Ultrasonic motor and having a moving body is frictionally driven by the piezoelectric vibrator according to any one of claims 1 7. An electronic apparatus comprising the piezoelectric vibrator according to claim 1.

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