JPH04193076A - Standing wave type ultrasonic motor, and analog electronic clock having standing wave type ultrasonic motor - Google Patents

Abstract

PURPOSE:To suppress the drop of electric-mechanic conversion efficiency, the complication of structure, etc., to the utmost, and improve the performance of a motor even at thinning and diameter reduction by putting the oscillator consisting of an oscillator part and a piezoelectric element approximately in the shape of an annulus ring thereby reducing the resonance frequency. CONSTITUTION:An oscillator part 301 is nearly in the shape of an annulus ring, and is in such shape that it is integrally fixed to and supported by the center shaft 102 through an oscillator part supporting member 303 only at the part of the node of the deflection standing wave ingredients oscillated in circumferential direction. For the oscillator part 301, projections 302 are arranged alternately at approximately middle positions between the loops and the nodes of the deflection standing wave ingredients. The oscillator part 301, the projections 302, and the oscillator part supporting member 303 may be one body or separate structures, and also as regards the quality of material, they need not be necessarily the same. As above, since the oscillator consisting of the oscillator part 301 and the piezoelectric element 304 is made approximately in the shape of an annulus ring, the reduction of the resonance frequency becomes possible, and the miniaturization and diameter reduction of the oscillator can be materialized.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is directed to a movable body using a deflection standing wave generated in the circumferential direction of the vibrating body by utilizing the expansion and contraction motion of a piezoelectric element or an electrostrictive element. This invention relates to the structure of a standing wave type ultrasonic motor that frictionally drives a motor, and an analog electronic timepiece using the same.

[Summary of the invention]

The present invention relates to a standing wave type ultrasonic motor that utilizes a flexural standing wave component, and includes a fixed base having a central axis and a fixed base that is fixed so as to be integral with the central axis only at the nodes of the flexural standing wave. Approximately midway between the supported vibrating body, the ring-shaped piezoelectric element or electrostrictive element bonded to at least one side of the vibrating body, and the antinode and node of the flexural standing wave generated in the vibrating body. A configuration consisting of protrusions provided every other time, a movable body disposed so as to be in pressure contact with the protrusions and to use the central axis as a rotational guide, and a pressurizing means for pressurizing the movable body. By doing so, even when downsizing the standing wave type ultrasonic motor in diameter, high torque can be achieved without sacrificing electromechanical conversion efficiency, and this structure can stabilize motor performance and improve efficiency. This is what I did.

Furthermore, an analog electronic timepiece can be obtained by the display means driven by the standing wave type ultrasonic motor, and it is possible to realize a smaller N-type, higher torque, and lower power consumption.

[Conventional technology]

Conventionally, a traveling wave type ultrasonic motor having a structure as shown in FIG. 2 has been known. In a conventional traveling wave type ultrasonic motor, the center of a vibrating body 203 is fixedly supported on a central shaft 202 installed on a fixed base 201, and the outer periphery of the vibrating body 203 is guided by the central shaft 202 as a rotation center. The movable body 205 is provided so as to pressurize only the movable body 205, and a spring member 206 is fixed on the central axis with a washer 207 and a stopper 208 as a pressure regulating mechanism for the movable body 205. At this time, by applying two high frequency voltages with different phases to the piezoelectric element 204, a traveling wave is excited in the vibrating body part 203, and the movable body 205 rotates through the HWI force with the vibrating body part 203. That's why it becomes 0
For example, such a conventional structure is disclosed in Japanese Patent Application Laid-Open No. 63-305770.

In addition, the structure of a conventional standing wave type ultrasonic motor is such that a contact portion that comes into contact with the moving body is provided between the node and the antinode of the standing wave generated in the vibrating body, and the structure rotates the moving body in one direction. For example, JP-A No. 63-107472, JP-A No. 63-107473, and JP-A No. 63-10
Japanese Patent No. 7474 discloses the structure of a conventional standing wave motor.

Further, as a conventional analog electronic timepiece, one having a structure as shown in FIG. 9 has been known.

In a conventional analog electronic watch, the stator 902
is arranged on the upper surface of the stator 901, and a magnetic core 903 is in contact with and screwed onto the upper surface of the stator 902. magnetic core 9
A coil wire 905 is wound around 03 and wired to a drive control circuit (not shown). A rotor 907 is rotatably incorporated into a rotor hole 906 of the stator 902, and the rotational movement of the rotor 907 is caused by a fifth wheel & pinion 908, a fourth wheel & pinion 909,
The signal is transmitted to a fifth wheel 910, a minute wheel 911, a minute wheel (not shown), and an hour wheel 912. Here, the coil wire 90
If a predetermined voltage is applied to stator 90 at regular intervals, stator 90
The rotor 907 rotates due to the magnetic force of the hour wheel 912, and the hour hand 915 attached to the hour wheel 912 tells the time, and the minute hand 9 attached to the minute wheel 911 rotates.
16 to indicate the minutes, and the second hand 917 attached to the fourth wheel & pinion 909 to indicate the seconds.

[Problem to be solved by the invention]

Although the structure of the ultrasonic motor as described above has the advantage of being capable of forward and reverse rotation because it is a traveling wave type, as the ultrasonic motor becomes smaller and smaller in diameter, In order to avoid loss in the drive circuit etc. due to an increase in the resonant frequency of a vibrating body made of In such cases, the strain is released near the center of the vibrating body.
The problem was that electromechanical conversion efficiency decreased and strong excitation force could not be obtained. Furthermore, in order to solve this problem, a structure in which the vibrating body consisting of the vibrating body part 203 and the piezoelectric element 204 has a roughly annular shape is also disclosed, but in the case of a traveling wave type ultrasonic motor, the vibration nodes In addition, in conventional standing wave type ultrasonic motors, the entire vibrating body is Since it is an integrally formed rigid body, there are problems in that the drive frequency of the motor becomes high, the excitation force decreases, and it is difficult to improve the electromechanical conversion efficiency.

Furthermore, the ring-shaped standing wave ultrasonic motor has the problem that it is difficult to realize a support structure that is compatible with miniaturization.

Therefore, in order to solve these conventional problems, the purpose of the present invention is to suppress the decrease in electromechanical conversion efficiency and the complexity of the structure as much as possible, and to develop a stationary motor that can be expected to improve motor performance even when the motor is made thinner and smaller in diameter. The aim is to obtain a wave-type ultrasonic motor.

[Failure to solve the problem]

In order to solve the above problems, the present invention includes a fixed base having a central axis, a vibrating body part that is fixedly supported so as to be integral with the central axis only at the nodes of the flexural standing wave, and a vibrating body. a piezoelectric element or an electrostrictive element in an annular shape joined to at least one side of the vibrating body; and protrusions provided at approximately every other position between the antinode and the node of the flexural standing wave generated in the vibrating body. A standing wave type ultrasonic motor is constructed by having a movable body placed in pressure contact with the protrusion and using the central axis as a rotational guide, and a pressurizing means for pressurizing the movable body. This allows for smaller diameters, more stable performance, and higher efficiency.

[Effect]

In the standing wave type ultrasonic motor configured as described above, as the ultrasonic motor becomes smaller and smaller in diameter, the vibrating body consisting of the vibrating body and the piezoelectric element can be formed into a roughly annular shape, which causes resonance. Not only can the frequency be reduced, but also higher electromechanical conversion efficiency and stronger excitation force can be obtained compared to excitation by a vibration motor having a disc-shaped configuration and having no nodes in the radial direction. In addition, since it uses standing waves, it is possible to support the nodes of the standing waves, and since it can be driven with one high-frequency signal, only one conduction lead wire is required. At the same time, the booster circuit and drive circuit can also be rendered in one color. Furthermore, since the moving body is frictionally driven by the protrusion provided approximately midway between the antinode and the node of the standing wave, load fluctuations and vibrations are reduced compared to the case of the traveling wave type, which always contacts the moving body at the antinode position. Less susceptible to changes in sliding surfaces.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a diagram showing a longitudinal cross-sectional view of a standing wave type ultrasonic motor according to the present invention. The central axis 102 is integrated with the fixed base 101 by screwing or driving, and the vibrating body part 103 has a generally annular shape and is a node of a flexural standing wave generated in the circumferential direction of the vibrating body. The shape is such that it is integrally fixed and supported with the central shaft 102 only at the portion. At this time, the vibrating body portion 103 is made of an elastic member such as aluminum alloy, stainless steel, or brass.

The vibrating body portion 103 is supported by the central shaft 102 at the central portion. Further, the vibrating body portion 103 does not have to have an integral structure. If positioning when bonding the piezoelectric element 104 to the vibrating body part 103 is considered, the vibrating body part 103 may have a two-body structure. Note that the mechanical resonance frequency of the fixed base 101 and the central axis 102 is sufficiently far away from the vibrating body consisting of the vibrating body part 103, piezoelectric element 104, etc., and the support structure is such that almost no vibration leakage or attenuation occurs due to the influence of the support. It becomes. Furthermore, by forming the fixing base 101 and the central shaft 102 from a conductive material, they can be made to have substantially the same potential as the adhesive surface, thereby facilitating wiring.

Furthermore, the fixing base 101 and the central shaft 102 may have an integral structure.

The piezoelectric element 104 has an annular shape with a hole in the center.
A piezoelectric element consisting of more than one piezoelectric element, or a piezoelectric element consisting of several pieces divided in the circumferential direction, with several patterns of electrode parts provided in the circumferential direction and polarized in the thickness direction,
It is joined to at least one side of 03.

The protrusions 105 are provided at approximately every other intermediate position between the antinode and the node of the flexural standing wave generated in the vibrating body part 103 by the expansion and contraction movement of the piezoelectric element 104.
Due to the flexural standing wave excited by 3, the tip portion of the protrusion 105 produces an elliptical motion.

The moving body 106 includes a protrusion 10 provided on the vibrating body portion 103.
5 is placed in pressure contact with the tip portion of the shaft 5 by a pressure spring 107, and is arranged so that the central shaft 102 serves as a rotational guide. When the flexural standing wave is excited in the vibrating body portion 103, it is converted into a rotational motion of the movable body 106 in one direction.

By the way, the most distinctive feature of the present invention relates to the structure of the vibrating body consisting of the vibrating body section 103 and the piezoelectric element 104.

FIG. 3 shows a first embodiment of a vibrating body of a standing wave type ultrasonic motor according to the present invention. In Figure 3, (A>
CB) is a cross-sectional view, and CB) is a plan view.

The vibrating body portion 301 has a generally annular shape, and as shown in the figure, the vibrating body portion supporting member 30 is only at the node portions of the flexural standing wave component excited in the circumferential direction of the vibrating body portion 301.
It has a shape that is fixedly supported integrally with the central shaft 102 via the center shaft 102. The vibrating body portion 301 has protrusions 30 at every other position approximately midway between the antinode and the node of the flexural standing wave component.
The structure is such that 2 are placed. At that time, the vibrating body part 301, the protrusion 302, and the vibrating body part supporting member 30
3 may be of integral or separate structure, and do not necessarily have to be made of the same material. With the above structure, the vibrating body part 301 and the piezoelectric element 304
Since the vibrating body consisting of the above can be formed into a generally annular shape, it is possible to reduce the resonance frequency, and the size and diameter of the vibrating body can be reduced. Furthermore, since strain is more easily released near the center of the vibrating body compared to a disk-shaped vibrating body, it is possible to obtain high electromechanical conversion efficiency and strong excitation force.

In addition, since it uses standing waves, it can be driven with one high-frequency signal, so only one conduction lead wire is required, and at the same time, only one booster circuit and one drive circuit are required. The entire motor device can be downsized. Furthermore, since the moving body is frictionally driven by the protrusion provided approximately midway between the antinode and the node of the standing wave, load fluctuations and vibrations are reduced compared to the case of the traveling wave type, which always contacts the moving body at the antinode position. It has many characteristics such as being less susceptible to changes in the sliding surface.

In this example, the wave number of the flexural standing wave excited in the circumferential direction of the vibrating body is 2, and the protrusion 302 is located just at the part from the antinode to the node when viewed from the clockwise direction. Although an example is shown in which the movable body rotates clockwise when it is disposed in the middle, the wave number and the location of the protrusion are not limited to this.

FIG. 4 is a plan view showing an embodiment of a piezoelectric element of a standing wave type ultrasonic motor according to the present invention. In Figure 4, (A)
is the surface, that is, the adhesive surface side with the vibrating body part 301, (
B) shows an example of the back side, that is, the lead wire joining side. Note that this embodiment shows a case where two waves are excited in the vibrating body shown in FIG. 3. On the surface side of the ring-shaped piezoelectric element 401, fan-shaped electrode patterns 402a to 402d are formed which are divided into four at equal intervals in the circumferential direction, so that every other electrode pattern exhibits a piezoelectric effect in the opposite direction. It has been polarized. That is, the electrode pattern 40
Polarization processing is performed so that 2a and 402C are on the (+) side with respect to the electrode pattern 403 on the back side, and the t-pole patterns 402b and 402d are on the (-) side with respect to the electrode pattern 403 on the back side. become. On the other hand, on the back side of the piezoelectric element 401, there is an electrode pattern 40 on almost the entire surface.
3 is sufficient, but the alignment of the piezoelectric element 401 and the vibrating body at the time of joining greatly contributes to variations in the rotational direction and performance of the standing wave type ultrasonic motor according to the present invention. Therefore, in this embodiment, the electrode pattern 4
By providing a marking portion 404 on a portion of 03, alignment with the protrusion indicated by dotted lines in the figure during bonding can be facilitated.

5 and 6 show other embodiments of the vibrating body of the standing wave type ultrasonic motor according to the present invention, in which (A) shows a cross-sectional view and (B) shows a plan view. It is something. In the embodiment shown in FIG. 5, the wave number of the flexural standing wave excited in the circumferential direction of the vibrating body is 3. In this case, the shape of the electrode pattern of the piezoelectric element 504 is different from that shown in FIG. 4 above. Since the wave number of the flexural standing wave is 3 and the addend of the vibration is also 6, six vibrating body support members 503 are normally required as in this embodiment. However, as the number of vibrating body support members 503 increases, the shape of the vibrating body as a whole becomes infinitely closer to a disk shape. Therefore, as a structure in which the strength of the supporting portion is maintained, it is also possible to remove each vibrating body part supporting member 503 so that there are three vibrating body part supporting members 503. In addition, although the protrusion 502 has a generally trapezoidal shape, the protrusion 502 has a generally trapezoidal shape.
If the vibration mode of the bent surface of 2 itself is not sufficiently high compared to the driving frequency of the vibrating body part 5O1, the motor performance will deteriorate, so by making it into such a trapezoidal shape, this problem can be overcome. In addition, since the area of the tip of the protrusion 502 can be reduced, it is expected that the rotational performance of the motor will also be improved.

The embodiment shown in FIG. 6 shows a case where the wave number of the flexural standing wave excited in the circumferential direction of the vibrating body is 2, and all shapes other than the vibrating body part support member 603 are the same as in the previous embodiment. It is almost the same as the example.

Here, by providing a hole in the shape of the vibrating body part support member 603 from the vibration node part toward the center part, the purpose is to substantially release the strain in this part further than in the previous embodiment. There is. By forming the vibrating body support member 603 into such a shape, it is expected that a stronger excitation force can be obtained and the motor performance will also be improved.

FIG. 7 shows a longitudinal sectional view of an analog electronic timepiece using a standing wave type ultrasonic motor according to the present invention. The vibrating body part 702 with the piezoelectric element 703 glued to the back surface is connected to the central axis 7
04, and this center shaft 704 is fixed to the main plate 701.
Fix it with screws 705. A plurality of protrusions 706 are provided on the upper surface of the vibrating body section 702, and the movable body 70 is attached to the protrusions 706.
7 receives the pressure of the pressure spring 708, and the central axis 704
The lead wire 7 connected to the piezoelectric element 703 is guided and rotatably incorporated in the tip 709 of the
] 0 from a drive control circuit (not shown) to the piezoelectric element 703, the vibrating body portion 702 is bent and deformed, and the movable body 7 is deformed by the deformation of the protrusion 706.
07 will be rotated at a constant speed. The moving body gear 711 on the outer periphery of the moving body 707 is the fourth type 712.
Further, the third die 713, minute wheel 714, hour wheel (not shown), and hour wheel 715 are rotated at a constant speed. At that time, if the period of the high-frequency voltage applied to the piezoelectric element 703 and the number of teeth of each gear mentioned above are set to predetermined values, the hour hand 718 attached to the hour wheel will tell the hour, and the minute hand 719 attached to the minute wheel will tell the minutes. , Second hand 72 attached to the number 4 model
0 allows seconds to be displayed.

In addition to displaying the time information using multiple train wheels and hands as described above, it can also be done by attaching hands or indicators directly to the moving body 707, which can be done using the dial 72 in FIG.
It can be viewed from the side where the pressure spring 708 is located, or vice versa. Further, by adjusting the high frequency voltage applied to the piezoelectric element 703, the second hand 720 can be moved in steps every second or continuously.

FIG. 8 shows a longitudinal sectional view of a two-hand analog electronic timepiece using a standing wave type ultrasonic motor according to the present invention.

The rotation of the movable body gear 811 is performed by the fourth type 812 and the third type 81.
3. The information is transmitted to the third die 814, and the minute hand 817 attached to the fourth die displays the minutes, and the hour hand 816 attached to the third die displays the minutes. This two-hand analog electronic timepiece can be easily realized by simply replacing some parts of the three-hand analog electronic timepiece shown in FIG. 6, and can also be made thinner and have higher torque.

(Effects of the Invention) As described above, the present invention includes: a fixed base having a central axis; a vibrating body portion fixedly supported so as to be integral with the central axis only at the node portions of the flexural standing waves; An annular piezoelectric element or @strain element bonded to at least one side of the vibrating body, and provided at approximately every other position approximately midway between the antinode and the node of the flexural standing wave generated in the vibrating body. With a simple configuration including a projection, a movable body arranged so as to make pressure contact with the protrusion and use the central axis as a rotational guide, and a pressurizing means for pressurizing the movable body, the following effects are achieved. .

■ Even when ultrasonic motors are made smaller and smaller in diameter, the resonant frequency can be reduced because the vibrating body consisting of the vibrating body part or the piezoelectric element can be formed into a roughly annular shape, and the radial direction of the disc-shaped shape can be reduced. However, it is possible to obtain higher electromechanical conversion efficiency and stronger excitation force compared to excitation in a vibration mode that does not have a node, so that the efficiency of the motor can be increased.

■ Since it is very simple in terms of structure, it is easy to reduce the size and diameter, and it is also excellent in mass production.

■ Since it is a standing wave type ultrasonic motor, rotational movement is possible with only one high-frequency signal, so only one booster circuit and one drive circuit are required, so the entire control circuit is included. Can be made smaller.

■ Since the moving body is frictionally driven by the protrusion provided approximately midway between the antinode and node of the standing wave, load fluctuations and sliding are less likely to occur compared to the traveling wave type, which always contacts the moving body at the antinode position. Stable motor performance can be obtained even with changes in the dynamic surface.

In addition, the analog electronic timepiece using the standing wave type ultrasonic motor of the present invention does not require the conventional coil block, stator, rotor, gear train, etc., so it is possible to realize a small and thin analog electronic timepiece. It has the unique effect of being able to change between a three-hand watch and a two-hand watch, and between continuous hand movement and step hand movement, with just a few changes to parts.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a standing wave type ultrasonic motor according to the present invention, FIG. 2 is a vertical cross-sectional view of a conventional ultrasonic motor, and FIG. 3 is a vertical cross-sectional view of a standing wave type ultrasonic motor according to the present invention. A sectional view and a plan view showing a first embodiment of the vibrating body, FIG. 4 is a plan view showing an embodiment of a piezoelectric element of a standing wave type ultrasonic motor according to the present invention,
FIG. 5 is a sectional view and a plan view showing a second embodiment of the vibrating body of the standing wave type ultrasonic motor according to the present invention, and FIG. A cross-sectional view and a plan view showing a third embodiment of the vibrating body, FIG. 7 is a vertical cross-sectional view of a three-hand analog electronic timepiece using a standing wave type ultrasonic motor according to the present invention, and FIG. 6101.201... is a vertical cross-sectional view of a two-hand analog electronic timepiece using a standing wave type ultrasonic motor according to the invention, and FIG. 9 is a vertical cross-sectional view of a conventional analog electronic timepiece. ......Fixed base 102.202.704.804...Central axis 103.203.3 old, 501.601.702.
802... Vibrating body part 104.204.401.504
．． 604.703.803...Indenter 402.4
03・・・・・・・・・Electrode pattern 105.3
02.502.602.7.06.806... Protrusion 303.503.603... Vibrating body support member 106.205.707.807...
・Mobile object 107.708.808 ・・・・・・・・・
...Pressure springs and above Applicant Keisuke Hayashi Patent attorney and agent for Seiko Electronics Co., Ltd. Figure 2. Figure 3. Closed 601 Motion body structure 602 Missing (/ \) tka

Claims (2)

[Claims] (1) In a standing wave type ultrasonic motor that frictionally drives a moving body by a standing deflection wave generated in the circumferential direction of the vibrating body by utilizing the expansion and contraction motion of a piezoelectric element or an electrostrictive element, the standing wave The wave-type ultrasonic motor includes a fixed base having a central axis, a vibrating body portion made of an elastic member that is fixedly supported so as to be integral with the central axis only at the nodes of the flexural standing wave, and An annular piezoelectric element or an electrostrictive element bonded to at least one side of the body part, and provided at approximately every other intermediate position between an antinode and a node of the flexural standing wave generated in the vibrating body part. The movable body is arranged such that the movable body is in pressure contact with the protrusion and is rotationally guided by the central axis, and a pressurizing means for pressurizing the movable body. Standing wave type ultrasonic motor. (2) a fixed base having a central axis; a vibrating body portion made of an elastic member fixedly supported so as to be integral with the central axis only at the node portions of the standing flexural waves generated in the circumferential direction; an annular piezoelectric element or an electrostrictive element joined to at least one side of a vibrating body part; a driving means for generating a piezoelectric effect in the piezoelectric element or a driving means for generating an electrostrictive effect in the electrostrictive element; a drive control means for transmitting constant time information to the drive means; a protrusion provided at approximately every other intermediate position between an antinode and a node of the standing wave generated in the vibrating body; A movable body arranged so as to be in pressure contact and to use the central axis as a rotation guide, a pressurizing means for pressurizing the movable body, and a display means provided on the movable body or by the movable body. An analog electronic timepiece using a standing wave type ultrasonic motor, characterized by having a driven display means.