JP5219438B2 - Ultrasonic motor - Google Patents

Description

  The present invention relates to an ultrasonic motor that excites a vibration body by applying a drive signal to an electromechanical energy conversion element and applies a driving force by friction to a moving body pressed by the vibration body.

  An ultrasonic motor is a motor configured to generate high-frequency vibration by applying an AC voltage to an electro-mechanical energy conversion element such as a piezoelectric element, and to extract the vibration energy as a continuous mechanical motion (patent) Literature 1 and Patent literature 2).

  FIG. 9 shows an example of a conventional ultrasonic motor.

  In this ultrasonic motor, a short cylindrical piezoelectric element 80 is divided into four-phase (A +, A-, B +, B-) electrodes in the circumferential direction, and the driving state of the piezoelectric element 80 is part of the A + phase. An S phase 89 for detecting the above is disposed.

  The A + phase and the A− phase of the piezoelectric element 80 are arranged to face each other in the radial direction, and the B phase and the B− phase are radial to each other at positions shifted by 90 degrees with respect to the A + phase and the A− phase. Are arranged opposite to each other.

  The piezoelectric element 80 is connected to a drive circuit via a flexible printed circuit board 88, and the drive circuit is connected to each phase of an oscillator 85, a phase shifter 86, a controller 87, and a piezoelectric element 80, a switching circuit 81, 82, 83, 84.

  The oscillator 85 switches the A + phase switching circuit 81 and the A− phase switching circuit 82 to give drive signals to the A + phase and the A− phase of the piezoelectric element 80.

  The phase shifter 86 shifts the drive signal of the oscillator 85 by 90 degrees and switches the B + phase switching circuit 83 and the B− phase switching circuit 84 to apply the drive signals to the B + phase and the B− phase of the piezoelectric element 80.

  Then, when a drive command is sent from the controller 87 to the oscillator 85, the A + phase and the A− phase of the piezoelectric element 80 vibrate 180 degrees out of phase with each other by the switching operation of the A + phase switching circuit 81 and the A− phase switching circuit 82. .

  At this time, due to the switching operation of the B + phase switching circuit 83 and the B− phase switching circuit 84 through the phase shifter 86, the phase is shifted 90 degrees with respect to the B + phase of the piezoelectric element 80, and the phase is shifted 180 degrees from the B− phase. The drive signal is given, and the piezoelectric element 80 vibrates. In response to this vibration, a signal is output from the S phase 89, and the controller 87 controls the ultrasonic motor based on the signal.

  However, in the conventional ultrasonic motor, since the S phase 89 is provided in a part of the A + phase of the piezoelectric element 80, the sizes of the A + phase and other phases are different. As a result, the output obtained from the A + phase is different, and a circuit for adjusting the output is separately required.

In view of this, a technique has been proposed in which the S phase is installed at another location, connected to an external control circuit by a lead wire, and the lead wire is fixed to the piezoelectric element by soldering (Patent Document 3).
JP-A-3-289375 JP-A-7-193291 Japanese Patent Publication No. 04-061593

  However, in the above-mentioned Patent Document 3, there is a problem that the lead wire is easily dropped due to a soldering defect, and that the solder melting temperature is difficult to reach due to the propagation of heat to the piezoelectric element and the vibrating body.

  Furthermore, there is a possibility that the piezoelectric element is depolarized due to variations in the vibration characteristics of the vibrator due to the state of solder attachment, or due to the temperature rise of the piezoelectric element during soldering.

  Therefore, the present invention can easily and stably extract a signal output from the piezoelectric film functioning as the S phase without disconnection due to vibration and without providing a circuit for adjusting the output of the driving phase. An object of the present invention is to provide an ultrasonic motor capable of

In order to achieve the above object, an ultrasonic motor according to the present invention applies a drive signal to an electromechanical energy conversion element having a plurality of electrodes to generate vibration in a vibrating body, and a moving body in contact with the vibrating body. in the ultrasonic motor that moved, the electrical - between the mechanical energy conversion element and the vibrating body, said electrical - substrate having contacts for supplying a driving signal to the energy transducer is sandwiched, the vibrating body , the piezoelectric film for dynamic detection vibration in the substrate and abutting surface are directly deposited, the substrate for the vibrating body to output the potential difference generated in the piezoelectric film for the vibration detection by the vibration It has a contact .

  According to the present invention, the vibration detection piezoelectric film is directly formed on the surface of the vibrating body on which the electromechanical energy conversion element abuts. Thereby, the signal output from the piezoelectric film functioning as the S phase can be easily and stably extracted without disconnection due to vibration and without providing a circuit for adjusting the output of the driving phase.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a cross-sectional view along an axial direction for explaining an ultrasonic motor according to a first embodiment of the present invention.

  As shown in FIG. 1, the ultrasonic motor of this embodiment includes a piezoelectric element (electro-mechanical energy conversion element) 1 having a plurality of electrodes arranged in a motor case composed of an outer cylinder 6 and a bottom plate 8. .

  A flexible printed circuit board 2 is electrically connected to the piezoelectric element 1, and vibrators 3 and 4 that transmit vibrations of the piezoelectric element 1 are disposed on both sides in the axial direction of the piezoelectric element 1.

  The vibrators 3 and 4 are joined to each other by a welded portion 5, whereby an axial preload is applied to the piezoelectric element 1 and the flexible printed circuit board 2.

  FIG. 2 is a perspective view for explaining a method for attaching the flexible printed circuit board 2.

  As shown in FIG. 2, the flexible printed board 2 is sandwiched between the piezoelectric element 1 and the vibrator (vibrating body) 3 in the axial direction.

  Further, in the vibrator 3, a piezoelectric film 20 directly formed by aerosolizing and spraying a fine powder of a raw material of a piezoelectric body is provided on a surface of the vibrator 3 on which the flexible printed circuit board 2 is pressed by the piezoelectric element 1. ing.

  Returning to FIG. 1, the inner peripheral end of the support plate 7 is fixed to the outer periphery of the piezoelectric element 1, and the support plate 7 passes through the gap between the vibrators 3 and 4, and the outer peripheral end is the inner peripheral portion of the outer cylinder 6. It is elastically fixed to.

  A rotary shaft 11 passes through the inner peripheral portion of the piezoelectric element 1, the flexible printed circuit board 2, and the vibrators 3 and 4 through a gap, and the rotary shaft 11 is press-fitted and fixed to the outer cylinder 6 and the bottom plate 8. 9 and 10 are rotatably supported.

  An E-ring 12 that restricts the movement of the rotating shaft 11 in the axial direction is fitted on the outer peripheral surface of the rotating shaft 11 adjacent to the bearing 9.

  A rotor (moving body) 13 is disposed between the end wall of the outer cylinder 6 and the vibrator 3 while being press-fitted and fixed to the rotating shaft 11. A flange 14 made of a cylindrical elastic body is provided on the outer periphery of the rotor 13, and the flange 14 is in contact with the vibrator 3 in an axially opposed state.

  Further, a rotor (moving body) 15 is disposed between the bottom plate 8 and the vibrator 4 in a state of being extrapolated via a gap between the rotor 15 and the rotor 15 between the rotor 15 and the bottom plate 8. The presser 16 is disposed in a state where it is press-fitted and fixed to the rotary shaft 11. The rotor presser 16 presses the rotor 15 in the axial direction via the spring 17.

  Like the rotor 13, a flange 18 made of a cylindrical elastic body is provided on the outer periphery of the rotor 15, and the rotor presser 16 presses the rotor 15 in the axial direction via the spring 17, 18 are elastically pressed against the vibrators 3 and 4, respectively.

  Since the driving principle is publicly known (Japanese Patent Laid-Open No. 3-289375, etc.), it will be briefly described. The piezoelectric element 1 vibrates by a driving signal applied through the flexible printed circuit board 2, and the vibration is caused by the vibrators 3 and 4. And the vibration expands at the outer periphery of the vibrators 3 and 4. A rotational force is generated in the flange 14 and the flange 18 by the vibration wave expanded on the outer peripheral portions of the vibrators 3 and 4, and the rotational force is transmitted to the rotor 13 and the rotor 15 to rotate the rotating shaft 11.

  At this time, electric power is generated in the aforementioned piezoelectric film 20 provided in the vibrator 3 due to the behavior of vibration applied to the vibrator 3, and a signal output from the piezoelectric film 20 is taken out by the flexible printed board 2.

  In order to avoid vibration attenuation, it is preferable to use a flexible printed circuit board 2 that does not have an adhesive layer between the base sheet and the substrate electrode.

  FIG. 3 is a block diagram for explaining a drive circuit of the piezoelectric element 1.

  As shown in FIG. 3, the short cylindrical piezoelectric element 1 is divided into four-phase (A +, A-, B +, B-) electrodes in the circumferential direction.

  The A + phase and the A− phase of the piezoelectric element 1 are arranged to face each other in the radial direction, and the B phase and the B− phase are radial to each other at positions shifted by 90 degrees with respect to the A + phase and the A− phase. Are arranged opposite to each other.

  The piezoelectric element 1 is connected to a drive circuit via the flexible printed circuit board 2, and the drive circuit is connected to each phase of the oscillator 25, the phase shifter 26, the controller 27, and the piezoelectric element 1, 22, 23, 24.

  The oscillator 25 switches the A + phase switching circuit 21 and the A− phase switching circuit 22 to give drive signals to the A + phase and the A− phase of the piezoelectric element 1.

  The phase shifter 26 shifts the drive signal of the oscillator 25 by 90 degrees and switches the B + phase switching circuit 23 and the B− phase switching circuit 24 to apply the drive signal to the B + phase and the B− phase of the piezoelectric element 1.

  When a drive command is sent from the controller 27 to the oscillator 25, the A + phase and the A− phase of the piezoelectric element 1 vibrate 180 degrees out of phase with each other by the switching operation of the A + phase switching circuit 21 and the A− phase switching circuit 22. .

  At this time, due to the switching operation of the B + phase switching circuit 23 and the B− phase switching circuit 24 through the phase shifter 26, the phase is shifted 90 degrees with respect to the B + phase of the piezoelectric element 1, and the phase is shifted 180 degrees from the B− phase. The drive signal is given, and the piezoelectric element 1 vibrates.

  Further, the piezoelectric film 20 formed directly on the vibrator 3 is connected to the controller 27.

  FIG. 4 is a diagram showing a circuit pattern on the front surface side of the flexible printed circuit board 2.

  In FIG. 4, contacts (shaded portions in the figure) 30, 31, 32, 33 corresponding to the A + phase, A− phase, B + phase, and B− phase of the piezoelectric element 1 are provided on the surface side of the flexible printed circuit board 2. These contacts 30, 31, 32, 33 are in contact with the respective phases of the piezoelectric element 1 and are energized.

  FIG. 5 is a diagram showing a circuit pattern on the back side of the flexible printed circuit board 2.

  In FIG. 5, a vibration detection contact 35 is provided on the back side of the flexible printed circuit board 2.

  The contact 35 is in contact with the piezoelectric film 20 formed on the contact surface of the vibrator 3 with the flexible printed board 2, and a potential difference is generated in the piezoelectric film 20 due to the movement of the vibrator 3, and the signal is sent to the contact 35. Through the through hole 36 and output to the drive circuit. This signal is referred to as an S-phase signal and is used by the controller 27 for controlling the ultrasonic motor.

  In addition, since control of the ultrasonic motor by the S phase signal is publicly known (Japanese Patent Publication No. 04-061593 etc.), description is abbreviate | omitted here.

  Next, a method for directly forming the piezoelectric film 20 on the vibrator 3 will be described.

  FIG. 6 is a view schematically showing an apparatus for producing a ceramic structure by an aerosol deposition method.

  As shown in FIG. 6, the manufacturing apparatus 41 includes a film forming unit 42 and an aerosol generating unit 43, and an aerosol in which ceramic fine particle powder generated in the aerosol generating unit 43 is dispersed in a gas is transmitted by an aerosol transport pipe 44. It is conveyed to the film forming unit 42.

  The film forming unit 42 includes a vacuum chamber 56 that is evacuated by a vacuum pump 55. The film forming unit 42 is transported by the transport pipe 44 from a nozzle 45 disposed at the end of the transport pipe 44 led into the vacuum chamber 56. The aerosol 46 is sprayed onto the substrate 47 to directly form the film 48 on the substrate 47. Thereby, a ceramic structure 49 made of the substrate 47 and the film 48 is produced. The substrate 47 is normally fixed to the stage 50, and the film 48 is formed while moving the substrate 47 in the XY direction 51.

  The aerosol generation unit 43 includes an aerosol generator 52 and a mass flow controller 54 that injects gas into the aerosol generator 52 through the gas transfer pipe 53, and the end of the aerosol transfer pipe 44 is connected to the aerosol generator 52. Inserted at the top.

  In the ceramic structure manufacturing apparatus by the aerosol deposition method described above, in this embodiment, a piezoelectric raw material such as PZT (lead zirconate titanate) is used as the ceramic, and the metal of the ultrasonic motor is used as the substrate 47. A manufactured vibrator 3 is installed.

  By directly forming the piezoelectric material on the vibrator 3 by the same method, the piezoelectric film 20 having a uniform composition can be easily formed in one film forming process.

  As described above, in the present embodiment, the flexible printed circuit board 2 is sandwiched between the vibrators 3 and 4 so as to be in pressure contact with the piezoelectric element 1 and is integrally fastened to thereby feed the drive signal to the piezoelectric element 1. Do.

  In addition, the piezoelectric film 20 is directly formed on the end surface of the vibrator 3 opposite to the bonding surface of the flexible printed circuit board 2 of the piezoelectric element 1.

  Thereby, the signal output from the piezoelectric film 20 can be easily and stably extracted without disconnection due to vibration.

  Further, by directly forming the piezoelectric film (S phase) 20 on the vibrator 3, it is not necessary to provide the S phase in the driving piezoelectric element 1, and the shape of each phase of the piezoelectric element 1 is made the same. Therefore, it is not necessary to provide a circuit for adjusting the output of the drive phase.

  Further, the area and configuration of the S phase can be easily changed to an optimal shape, and the controllability can be improved by directly detecting the vibration of the vibrator 3 with the piezoelectric film 20.

(Second Embodiment)
Next, with reference to FIG. 7 and FIG. 8, the ultrasonic motor which is the 2nd Embodiment of this invention is demonstrated.

  FIG. 7 is a plan view of the front surface side of the flexible printed circuit board used in the ultrasonic motor according to the second embodiment of the present invention, and FIG. 8 is a plan view of the back surface side of the flexible printed circuit board shown in FIG. Note that portions that overlap or correspond to the first embodiment will be described with the same reference numerals.

  In the present embodiment, as shown in FIG. 8, vibration detection contacts 35 a and 35 b are provided on the back surface of the flexible printed circuit board 2.

  The contacts 35a and 35b and the piezoelectric film 20 formed on the contact surface of the vibrator 3 with the flexible printed board 2 are in contact with each other, and a potential difference is generated by the movement of the vibrator 3.

  The contacts 35a and 35b correspond to the positions of the A + phase and B + phase of the piezoelectric element 1, respectively, and can detect the operation of the A + phase and the operation of the B + phase. At this time, the signal passes through the contact holes 35a and 35b, passes through the through holes 36a and 36b, and is output to the drive circuit via the contact point 75 as shown in FIG.

  As shown in FIG. 7, contacts 30, 31, 32, 33 corresponding to the A + phase, A− phase, B + phase, and B− phase of the piezoelectric element 1 are provided on the surface side of the flexible printed circuit board 2. It has been.

  In this case, since the operations of the A + phase and B + phase of the piezoelectric element 1 can be detected through the contacts 35a and 35b, the phase difference of the drive signal, which is one of the ultrasonic motor control methods, can be changed to control the speed. It becomes possible.

  Furthermore, since the behavior of the vibrator 3 can be directly detected, the configuration of the control circuit and software for control can be simplified. Other configurations and operational effects are the same as those in the first embodiment.

  In addition, this invention is not limited to what was illustrated by said each embodiment, In the range which does not deviate from the summary of this invention, it can change suitably.

  For example, in each of the above embodiments, the piezoelectric film 20 is formed on the vibrator 3 by the aerosol deposition method, but the present invention is not limited to this.

  For example, a piezoelectric film may be formed by applying a printing liquid containing a piezoelectric raw material to the vibrator 3 (see Japanese Patent Laid-Open No. 63-31480), and depositing a piezoelectric raw material on the vibrator 3. (See JP-A 63-186572), a piezoelectric film may be formed.

It is sectional drawing which follows the axial direction for demonstrating the ultrasonic motor which is the 1st Embodiment of this invention. It is a perspective view for demonstrating the attachment method of a flexible printed circuit board. It is a block diagram for demonstrating the drive circuit of a piezoelectric element. It is a top view of the surface of a flexible printed circuit board. It is a top view of the back surface of a flexible printed circuit board. It is a figure which shows typically the production apparatus of the ceramic structure by the aerosol deposition method. It is a top view of the surface of the flexible printed circuit board used for the ultrasonic motor which is the 2nd Embodiment of this invention. It is a top view of the back surface of the flexible printed circuit board shown in FIG. It is a block diagram for demonstrating the conventional ultrasonic motor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piezoelectric element 2 Flexible printed circuit board 3 Vibrator 4 Vibrator 11 Rotating shaft 13 Rotor 14 Head 15 Rotor 18 Head

Claims (5)

In an ultrasonic motor that causes a vibration body to vibrate by applying a drive signal to an electro-mechanical energy conversion element having a plurality of electrodes and moves a moving body that contacts the vibration body,
A substrate having a contact for supplying a drive signal to the electro-mechanical energy conversion element is sandwiched between the electro-mechanical energy conversion element and the vibrating body,
The vibrating body, the piezoelectric film for dynamic detection vibration in the substrate and abutting surface are deposited directly,
The ultrasonic motor according to claim 1, wherein the substrate has a contact for outputting a potential difference generated in the vibration detecting piezoelectric film when the vibrating body vibrates .   2. The ultrasonic wave according to claim 1, wherein the piezoelectric film is formed directly on the vibrating body by injecting aerosolized fine powder of a raw material of the piezoelectric body onto the vibrating body. motor.   2. The ultrasonic motor according to claim 1, wherein the piezoelectric film is formed directly on the vibrating body by applying a printing liquid containing a raw material of the piezoelectric body to the vibrating body.   The ultrasonic motor according to claim 1, wherein the piezoelectric film is formed directly on the vibrating body by depositing a raw material of the piezoelectric body on the vibrating body. The substrate, the electro - the surface different from the contacts arranged face for connecting a drive signal to the energy transducer, arranged contacts for outputting the electric potential difference generated in the piezoelectric film for the vibration detection The ultrasonic motor according to any one of claims 1 to 4, wherein the ultrasonic motor is provided.

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