JP2012135090A - Piezoelectric drive device, control method of piezoelectric drive device, and electronic clock - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric drive device capable of inputting minimum energy necessary to drive a driven body thereby saving energy.SOLUTION: A piezoelectric drive device includes a piezoelectric actuator, driving amount detection means for detecting a driving amount of the driven body, and driving control means. If the driving amount of the driven body reaches a set value after a first driving signal is input to the piezoelectric actuator, the driving control means makes input energy of a next first driving signal to be input smaller than the previous input energy. If the driving amount of the driven body does not reach the set value after the first driving signal is input, the driving control means inputs a second driving signal. If the driving amount of the driven body reaches the set value after the second driving signal is input, the driving control means makes the input energy of the next first driving signal to be input the same as the previous input energy. If the driving amount of the driven body does not reach the set value after the second driving signal is input, the driving control means inputs a third driving signal till the driving amount reaches the set value and makes the input energy of the next first driving signal to be input larger than the previous input energy.

Description

  The present invention relates to a piezoelectric driving device, a control method for a piezoelectric driving device, and an electronic timepiece.

  When a step movement of a constant angle is performed like a hand of an electronic timepiece, an electromagnetic stepping motor is generally used, and is widely used as a driving source of the electronic timepiece. When driving a time hand (pointer) using an electromagnetic stepping motor, there is a problem that it malfunctions or stops due to the influence of a magnetic field. In addition, since the driving force is small, a multistage reduction gear train is required, which is disadvantageous for downsizing.

In order to solve these problems, a piezoelectric drive device that drives a pointer with an ultrasonic motor (piezoelectric actuator) is known (see Patent Document 1).
The piezoelectric drive device of Patent Document 1 includes a piezoelectric actuator that drives a driven body, drive amount detection means that detects the drive amount of the driven body, and drive control means that controls the supply of a drive signal to the piezoelectric actuator. I have.

  As shown in FIG. 10, the drive control means inputs the first drive signal of the input time t1 to the piezoelectric actuator and determines whether the drive amount of the driven body has reached the target value by the drive amount detection means. It was. In Patent Document 1, as shown in FIG. 10, a state where the driven body reaches the target drive amount only by the input of the first drive signal and the detection result is ON is set as a stable control state.

  If this stable state continues for a predetermined period, as shown in FIG. 11, the input time t1 of the first drive signal is shortened, and if the detection result is turned ON by this drive signal, the first drive signal Driven continuously for a predetermined period. Thereafter, the input time of the first drive signal was further shortened to reduce the input energy.

  On the other hand, when the detection result at the time of inputting the first drive signal is OFF, as shown in FIG. 12, the second drive signal whose input time is t2 and whose input energy is smaller than that of the first drive signal is detected. It was repeated and input until the result turned ON. When the next first drive signal is input, the first drive signal whose input energy is increased by extending the input time is input.

  By repeating the above operation, the drive control means of Patent Document 1 controls to a stable state in which the detection result is ON only by inputting the first drive signal.

JP 2008-228375 A

  By the way, in Patent Document 1, when the first drive signal is insufficient to drive the driven body to the target drive amount (in the case of insufficient energy), the second drive signal is input and driven. Since the input energy of the first drive signal is increased at the time of the driving step, it can be dealt with immediately.

On the other hand, when the first drive signal is larger than the energy required to drive the driven body by a predetermined drive amount (in the case of excessive energy), the drive signal with the excessive energy is continuously input for a predetermined period. There is a problem that wasteful energy is consumed and energy saving becomes insufficient.
For example, when a wristwatch is driven with a piezoelectric actuator, the energy required for driving changes depending on the direction of the watch. In other words, when the drive shaft of the pointer is oriented in the vertical direction, the pointer moves in a horizontal plane, so that the energy required for the drive is substantially constant.
On the other hand, when the driving shaft of the pointer is tilted from the vertical direction, the pointer moves, for example, in the vertical plane. In this case, since the driving energy differs greatly between when the pointer moves downward and when the pointer moves upward, the energy required to drive the pointer varies depending on the direction of the watch.

  Accordingly, since a large amount of drive energy is temporarily required, the pointer is not driven only by the first drive signal, the second drive signal is input to drive the pointer, and the first drive is performed during the subsequent drive steps. If the input energy of the signal has been increased, the first drive signal with a large input energy will continue to be supplied even if the energy required to actually drive the pointer has subsequently decreased. There was a problem that could not be achieved.

  An object of the present invention is to provide a piezoelectric driving device, a piezoelectric driving device control method, and an electronic timepiece that can be controlled to input a minimum amount of energy necessary for driving a driven body and can save energy. There is to do.

  The piezoelectric drive device of the present invention includes a piezoelectric element having a piezoelectric element, and having a vibrating body that vibrates when a driving signal is supplied to the piezoelectric element, and transmitting the vibration of the vibrating body to the driven body, and the driven A driving amount detecting means for detecting whether or not the driving amount of the body has reached a preset set value; and a drive control means for controlling the supply of a driving signal to the piezoelectric actuator; The means detects the drive amount of the driven body every time a drive signal is supplied to the piezoelectric actuator, and the drive control means inputs the first drive signal to the piezoelectric actuator, When the drive amount reaches the set value, the input energy of the first drive signal to be input next is made smaller than the previous input energy, and the first drive signal is input to the piezoelectric actuator. After that, when the drive amount of the driven body does not reach the set value, a second drive signal having an input energy smaller than the input energy of the first drive signal is input, and the second drive signal is input. When the drive amount of the driven body reaches the set value, the input energy of the first drive signal input next is maintained at the same input energy as the first drive signal input last time, and the second drive When the driving amount of the driven body does not reach the set value due to the input of a signal, the driving amount of the driven body has a third driving signal having an input energy smaller than the input energy of the first driving signal. The input energy of the first drive signal that is repeatedly input until the set value is reached and that is input next is made larger than the input energy of the first drive signal that is input last time.

According to the present invention, the following three types of control A to C are performed according to the input result of the first drive signal.
(A) When the drive amount of the driven body reaches a set value by inputting only the first drive signal After the drive control means inputs the first drive signal to the piezoelectric actuator, the drive amount of the driven body is When the set value is reached, the input energy of the first drive signal to be input next is made smaller than the previous input energy. For this reason, the input energy of the first drive signal gradually decreases, the drive amount of the driven body does not reach the set value only by the first drive signal, and reaches the set value by the input of the second drive signal (B) It will be controlled to the stable state.

(B) When the drive amount of the driven body reaches the set value by the input of the first drive signal and the second drive signal In this case, the drive control means performs the first drive to maintain the input energy of the first drive signal. The drive amount of the driven body does not reach the set value only by the signal, and the control in the stable state (B) reaching the set value by the input of the second drive signal is continued.

(C) When the drive amount of the driven body reaches the set value by the input of the first drive signal, the second drive signal, and the third drive signal In this case, the drive control means inputs the first drive signal to be input next Make the energy larger than the previous input energy. For this reason, the input energy of the first drive signal gradually increases, and accordingly, the input of the third drive signal becomes unnecessary. Therefore, the drive amount of the driven body does not reach the set value with only the first drive signal, and the first drive signal does not reach the set value. It is controlled to the stable state (B) that reaches the set value when two drive signals are input.

As described above, according to the present invention, even when the energy for driving the driven body fluctuates and the state (A) or (C) is reached, the control (B) is finally performed. Can transition to a state. In the control state of (B), the energy required for the driving amount of the driven body to become the set value cannot be ensured only by the first driving signal, and the second driving signal is input to input the second driving signal. The driving amount can be set to a set value. For this reason, the control that the drive amount of the driven body reaches the set value only by the first drive signal as in (A) does not continue, and it is possible to prevent the excessive energy consumption.
On the other hand, as in (C), the control in which the driving amount of the driven body reaches the set value by inputting the first to third driving signals, that is, the control in which the input energy of the first driving signal is insufficient is not continued. Since it is possible to quickly return to a state where it can be driven only by the input of the first and second drive signals, the drive time can be shortened.
As described above, the present invention reduces the energy when the input energy of the first drive signal is excessive, and increases the energy when the input energy is insufficient. Energy can be supplied, the driven body can be driven reliably, and energy saving can be realized.

In the present invention, the driving amount of the driven body reaches the set value means that if the driven body is a rotating body, the driven body is rotated by a preset angle. Is a member that moves linearly, the linear movement distance of the member is moved by the set length.
And a to-be-driven body can be continuously driven for every set amount by outputting a 1st drive signal at predetermined intervals (for example, 1 second interval). Therefore, if the driven body is a gear, it is possible to configure a timepiece in which the pointer is driven by the piezoelectric actuator by providing the pointer on the gear train linked to the gear.

In the piezoelectric driving device of the present invention, it is preferable that the drive control means controls the input energy by controlling a drive time while keeping a voltage of a drive signal constant.
When the input energy is controlled, if the voltage of the drive signal is kept constant and controlled by the drive time, a circuit configuration for varying the voltage becomes unnecessary, and the cost can be reduced.
The drive control means may control the input energy by controlling the voltage with the drive time of the drive signal constant. In this case, it is not necessary to lengthen the driving time in order to increase the input energy, and the driving time can be made constant regardless of the magnitude of the input energy, so that the driving time can be shortened.

  In the piezoelectric drive device of the present invention, the drive control means has reached the set value by the drive quantity detection means after the elapse of a predetermined time after inputting the drive signal to the piezoelectric actuator. The predetermined time is preferably longer than the time from when the drive signal input to the piezoelectric actuator is stopped until the drive system including the driven body stops.

Since the predetermined time is longer than the time from when the input of the drive signal to the piezoelectric actuator is stopped until the drive system including the driven body is stopped, the drive amount is reduced after the drive system is completely stopped. Since it can be detected, there is no detection time lag, and the determination can be made reliably including the influence of the inertia of the drive system. For this reason, highly accurate detection becomes possible.
In addition, when the driven body is driven at a fixed time interval, the predetermined time must be set within the fixed time interval, and specifically, until the next driving at the fixed time interval. It is necessary to set so that the driving of the predetermined driving amount is completed by performing the driving amount detection processing after the predetermined time elapses and the correction driving based on the detection. Accordingly, when the driven body is a pointer of a clock and the pointer is operated for 1 second, the predetermined time is naturally set within 1 second and is not set to be larger than 1 second. In this case, the predetermined time is naturally set within 20 seconds, and is not set longer than 20 seconds.

A method for controlling a piezoelectric driving apparatus according to the present invention includes a piezoelectric actuator that includes a piezoelectric element, and includes a vibrating body that vibrates when a driving signal is supplied to the piezoelectric element, and transmits the vibration of the vibrating body to a driven body. A piezoelectric device comprising: a drive amount detection unit that detects whether or not the drive amount of the driven body has reached a preset value; and a drive control unit that controls supply of a drive signal to the piezoelectric actuator. A method of controlling a driving device, wherein after a first drive signal is input to the piezoelectric actuator, when a drive amount of the driven body reaches the set value, an input of a first drive signal to be input next If the drive amount of the driven body does not reach the set value after the energy is made smaller than the previous input energy and the first drive signal is input to the piezoelectric actuator, the first drive signal is input. When the second drive signal having an input energy smaller than the energy is input and the drive amount of the driven body reaches the set value by the input of the second drive signal, the first drive signal to be input next is input. The input energy is maintained at the same input energy as the first drive signal input last time, and when the drive amount of the driven body does not reach the set value due to the input of the second drive signal, A first driving signal having an input energy smaller than the input energy is repeatedly input until the driving amount of the driven body reaches the set value, and the input energy of the first driving signal to be input next is first input. It is characterized by being larger than the input energy of the drive signal.
According to the present invention, the same effect as the piezoelectric driving device can be obtained.

The electronic timepiece of the invention includes the piezoelectric driving device and a time information display unit driven by the piezoelectric driving device.
If the time information display part of the electronic timepiece is driven by the piezoelectric driving device, it can be made thinner than when a stepping motor is used, and the drive amount of the time information display part can be detected with high accuracy. By controlling the driving based on this, it is possible to prevent the display of the timing information from being shifted, and it is possible to give an accurate instruction.

Here, it is preferable that the timing information display unit includes a pointer that is rotationally driven by the piezoelectric driving device.
The timekeeping information display unit driven by the piezoelectric drive device may display calendar information such as a date indicator or day indicator, but when driving an indicator indicating time such as an hour hand, minute hand, second hand, etc. Can be detected with high accuracy, and an electronic timepiece with high indication accuracy can be provided.

The top view which shows the principal part of the timepiece which concerns on embodiment of this invention. Sectional drawing which shows the rotation transmission apparatus of the said embodiment. The top view which shows the rotation transmission apparatus of the said embodiment. The block diagram which shows the circuit structure in the timepiece of the said embodiment. The flowchart which shows the control method of the said embodiment. 4 is a timing chart illustrating an example of driving signal control according to the embodiment. 4 is a timing chart illustrating an example of driving signal control according to the embodiment. 4 is a timing chart illustrating an example of driving signal control according to the embodiment. 4 is a timing chart illustrating an example of driving signal control according to the embodiment. The timing chart which shows the example of control of the drive signal of the prior art example of this invention. The timing chart which shows the example of control of the drive signal of the prior art example of this invention. The timing chart which shows the example of control of the drive signal of the prior art example of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[overall structure]
FIG. 1 is a plan view showing a schematic configuration of an electronic timepiece 1 as an electronic apparatus using a piezoelectric driving device according to the present embodiment, and FIG. 2 is a cross-sectional view of a main part thereof.
1 is a view of the electronic timepiece 1 as viewed from the side opposite to the time display side (the back cover side). In FIG. 1, the upward direction (the direction from the center toward the time adjustment mechanism 80) is the electronic timepiece. 1, 3 o'clock direction, the downward direction (the direction from the center toward the rotation transmission device 40) is the 9 o'clock direction, the right direction (the direction opposite to the direction from the center toward the piezoelectric actuator 20) is the 12 o'clock direction, and the left direction (from the center) The direction toward the piezoelectric actuator 20) is the 6 o'clock direction. FIG. 2 is a diagram in which the time display side of the electronic timepiece 1 is down (the base plate 3 side) and the back cover side is up (the train wheel bridge 4 side).

As shown in FIG. 1, the electronic timepiece 1 includes a piezoelectric driving device 10 that drives a pointer that displays time, a battery 2, an IC 5, and a crystal resonator 6. The IC 5, the crystal unit 6 and the like are provided on a circuit board (not shown). The battery 2 is held by a battery holding part.
The electronic timepiece 1 of the present embodiment is a two-hand type wristwatch that includes an hour hand and a minute hand as hands.

[Configuration of Piezoelectric Drive Device]
As shown in FIGS. 1 and 2, the piezoelectric driving device 10 that drives a pointer includes a piezoelectric actuator 20 and a rotation transmission device 40 that transmits an output of the piezoelectric actuator 20 to a pointer that is a rotation target.

[Configuration of piezoelectric actuator]
The piezoelectric actuator 20 includes a vibrating body 21 and a rotor 30. As shown in FIG. 2, the vibrating body 21 is a stainless steel that is approximately the same shape as the piezoelectric elements 22 between two rectangular and plate-shaped piezoelectric elements 22 and is thinner than the piezoelectric elements 22. It has a laminated structure in which a reinforcing plate 23 made of steel or the like is sandwiched.
Examples of the piezoelectric element 22 include lead zirconate titanate (PZT (trademark)), crystal, lithium niobate, barium titanate, lead titanate, lead metaniobate, polyvinylidene fluoride, lead zinc niobate, lead scandium niobate, and the like. Various types of can be used.

The vibrating body 21 has a contact portion 25 at the end in the width direction of one short side. The contact portion 25 is obtained by a method such as cutting and forming the reinforcing plate 23, and a tip portion having a gently curved surface is protruded from the piezoelectric element 22. The vibrating body 21 maintains a posture in which the tip of the contact portion 25 is brought into contact with the outer peripheral surface of the rotor 30.
In the present embodiment, the contact portion 25 is formed at a position that is eccentric with respect to the center axis in the width direction of the vibrating body 21, so that the piezoelectric actuator 20 has a weight balance in the width direction of the vibrating body 21. It is configured to be unbalanced and bend easily. On the other short side of the vibrating body 21, a protrusion 26 similar to the contact portion 25 is formed at a target position with respect to the plane center of the vibrating body 21, and bending vibration of the vibrating body 21 is generated. It is made easier to occur.

A support portion 27 is formed on one side surface of the piezoelectric actuator 20 in the longitudinal direction. The support portion 27 is integrally formed with the reinforcing plate 23. The support portion 27 is fixed to a ground plate or the like with screws or the like.
In addition, a circuit board for piezoelectric elements is attached to the support portion 27, and lead wires arranged on the surface of the circuit board are connected to drive electrodes provided on the surface of the piezoelectric element 22, and the piezoelectric element 22 is connected to the piezoelectric element 22. The element 22 can be driven.

  When a voltage having a predetermined frequency is applied to the drive electrode of the vibrating body 21 as described above, the piezoelectric element 22 excites vibration in the longitudinal primary vibration mode that expands and contracts along the longitudinal direction. At this time, since the contact portions 25 and the protrusions 26 are provided at both ends of the diagonal line of the vibrating body 21, the weight of the vibrating body 21 is unbalanced with respect to the center line in the longitudinal direction as a whole. Due to this unbalance, the vibrating body 21 excites vibrations in a bending secondary vibration mode that bends in a direction substantially orthogonal to the longitudinal direction. Therefore, the vibrating body 21 excites vibrations that combine these longitudinal primary vibration mode and bending secondary vibration mode, and the contact portion 25 vibrates in a substantially elliptical orbit.

[Configuration of rotor]
The rotor 30 driven in contact with the vibrating body 21 is rotatably held by the rotor guide body 320. The rotor 30 and the rotor guide body 320 constitute a rotor block. Further, the rotor 30 is provided with a rotor gear 31 that rotates integrally with the rotor 30.

As shown in FIG. 1, the rotor guide body 320 is disposed so as to be swingable about a swing shaft 321, and one end of the pressing spring 35 is in contact with a pin 322 of the rotor guide body 320.
The other end of the pressing spring 35 is locked to a fixing pin 36 provided on a ground plate or the like, and the pressing spring 35 disposed between the fixing pin 36 and the rotor guide body 320 is bent to urge the rotor guide body 320. Has been.

  By urging the rotor guide body 320 by the pressing spring 35, the rotor 30 is brought into contact with the contact portion 25 of the piezoelectric actuator 20 with a predetermined contact force (contact pressure). For this reason, when the vibrating body 21 of the piezoelectric actuator 20 vibrates and the contact portion 25 vibrates in a substantially elliptical orbit, the rotor 30 with which the contact portion 25 is in contact with the side surface also rotates. In the present embodiment, in FIG. 1, the rotor 30 rotates clockwise. Therefore, in the present embodiment, one predetermined direction in which the rotor 30 is rotated is the clockwise direction in FIG.

[Configuration of rotation transmission device]
The rotation transmission device 40 transmits the rotational energy of the rotor 30 to the object to be rotated. As shown in FIGS. 1 to 3, the rotation detection wheel 41, the elastic device 42, the rotation restriction device 43, and the third A car 44, a second wheel 45, a minute wheel 46, and an hour wheel 47 are provided.

[Configuration of rotation detection vehicle]
The rotation detection wheel 41 includes a pinion 411 that meshes with the rotor gear 31 and a gear 412 that rotates integrally with the pinion 411, and is rotatably supported by the main plate 3 and the train wheel bridge 4.
The gear 412 includes a boss portion 412A disposed on the central axis, an annular rim portion 412B disposed on the outer periphery, and a plurality of spoke portions 412C provided radially from the boss portion 412A toward the rim portion 412B. Configured. For this reason, a hole is formed between the boss portion 412A and the rim portion 412B except for the spoke portion 412C.

[Configuration of elastic device]
The elastic device 42 includes a pinion 421, a shaft 422, a spring locking member 423, a bearing ring 424 fixed to the Geneva drive wheel 431 of the rotation regulating device 43, a locking pin 425, a spiral spring 426, and a cover 427. And. The Geneva drive wheel 431 is disposed so as to be rotatable with respect to the shaft 422 by a bearing ring 424 fixed at the center.
The pinion 421 rotates integrally with a shaft 422 rotatably supported by the main plate 3 and the train wheel bridge 4 and meshes with the gear 412 of the rotation detection wheel 41.

The spring locking member 423 is fitted to the shaft 422 and rotates integrally, and the end portion on the inner peripheral side of the spiral spring 426 is locked. The outer peripheral end of the spiral spring 426 is locked to the locking pin 425. Therefore, in this embodiment, the rotor transmission wheel in which the rotation from the rotor 30 is transmitted via the rotation detection wheel 41 is configured by the kana 421, the shaft 422, and the spring locking member 423 that rotate integrally. One end of a spiral spring 426 is engaged with the rotor transmission wheel.
The cover 427 is fixed at a predetermined plane position with respect to the shaft 422, and prevents an intermediate portion of the spring 426 from jumping out toward the train wheel bridge 4 side. Further, since the cover 427 is fixed to the shaft 422 at the predetermined plane position, as shown in FIG. 3, the locking pin 425 to which the outer end of the spiral spring 426 is fixed is determined on the side surface and positioned. can do. By this positioning, the Geneva drive wheel 431 is held at a predetermined rotational position by the elastic force of the spiral spring 426, that is, at a position where the locking pin 425 contacts the side wall of the cover 427.

  The spiral spring 426 is formed by winding a thin leaf spring wire having a rectangular cross section in a spiral shape counterclockwise from the center side toward the outer periphery side in a plan view in FIG. The spiral spring 426 is elastically deformed in the direction in which the number of turns increases by rotating the pinion 421, the shaft 422, and the spring locking member 423 in a clockwise direction before the Geneva drive wheel 431, and the pinion 421 The transmitted driving force can be stored as elastic energy.

  Further, the spiral spring 426 is locked to the spring locking member 423 and the locking pin 425 in a state of having an initial deflection (initial elastic deformation). Specifically, in a state where the piezoelectric actuator 20 is stopped, that is, in a state where the pinion 421, the shaft 422, and the cover 427 are stopped, the elastic force due to the initial deflection is caused by the locking pin 425 of the Geneva drive wheel 431. It is set to such an extent that it reliably contacts the side wall of the cover 427. In this state, the teeth 436 and the teeth 437 of the Geneva driven vehicle 435 are in contact with the regulating portion 433 of the Geneva driven vehicle 431, and the Geneva driven vehicle 435 is positioned in the rotation direction and the Geneva driven vehicle is driven. Even if a rotational force is generated from the vehicle 435 side, the rotation of the Geneva driven vehicle 435 is prohibited. Further, when the initial deflection is provided as described above, even if the hands such as the hour hand and the minute hand are heavy (the moment of inertia is large), it becomes easy to drive the hands.

[Configuration of rotation restricting device]
The rotation regulating device 43 is arranged so that the rotational energy of the rotor 30 is transmitted through the elastic device 42. That is, the rotation regulating device 43 constitutes a series path that transmits the rotational energy of the rotor 30 together with the rotor 30 and the elastic device 42. Such a rotation restricting device 43 includes a Geneva gear device that is a non-reversible tooth profile transmission device, a Geneva driving vehicle (primary gear) 431, and a Geneva driven vehicle (driven gear) 435 that is rotated by the Geneva driving vehicle 431. It has.
The Geneva drive wheel 431 is supported rotatably with respect to the shaft 422 via a bearing ring 424 fixed at the center. Then, claws (teeth) 432 that engage with the Geneva driven vehicle 435 are provided at two symmetrical positions around the rotation axis of the Geneva driving wheel 431, that is, at two intervals of 180 degrees in the rotation direction of the Geneva driving wheel 431. Yes. Further, a restricting portion 433 is configured by an arc-shaped outer peripheral surface between the two claws 432. The radius from the central axis of the restricting portion 433 is set larger than the root circle radius of the nail (tooth) 432 and smaller than the tip circle radius.

The Geneva driven vehicle 435 includes teeth 436 formed at five positions at intervals of 72 degrees in the rotation direction on the outer peripheral surface thereof, teeth 437 formed corresponding to the respective teeth 436, and a pinion 438 provided on the central axis. And.
The distance between the tooth 436 and the tooth 437 is a small distance of about 20 degrees with respect to the tooth 437 arranged in the counter-rotating direction with respect to the tooth 436, and the distance between the tooth 437 arranged in the rotating direction. Is a large interval of about 50 degrees.
When the two teeth 437 and 436 sandwiching the large gap portion are in contact with the restricting portion 433 of the Geneva drive wheel 431, the Geneva driven wheel 435 rotates in both the rotation direction and the counter-rotation direction. I can't. That is, the Geneva driven vehicle 435 is in a state in which the rotation is restricted by the Geneva driven vehicle 431.

The rotation restriction state of the Geneva driven wheel 435 is continued until the Geneva driving wheel 431 rotates and the claw 432 contacts the tooth 436. In the present embodiment, the rotation of the Geneva driven vehicle 435 is restricted while the Geneva driven vehicle 431 rotates 120 degrees.
When the claw 432 of the Geneva driven vehicle 431 comes into contact with the teeth 436 of the Geneva driven vehicle 435 and the Geneva driven vehicle 431 further rotates, the Geneva driven vehicle 435 also rotates in conjunction with it. Then, the rotation of the Geneva driven vehicle 435 stops at the position where the teeth 437 and 436 return to the state where they are in contact with the restricting portion 433.
In other words, in this embodiment, when the Geneva driven vehicle 431 rotates 180 degrees, while the Geneva driven vehicle 431 rotates 120 degrees (regulation range), the Geneva driven vehicle 435 is restricted from rotating and stopped. During the 60-degree rotation (driving range), the Geneva driven vehicle 435 rotates 72 degrees in conjunction with the Geneva driving vehicle 431. That is, the Geneva driven vehicle 435 rotates intermittently with the rotation of the Geneva driven vehicle 431.

  As described above, the Geneva driven wheel 435 is intermittently rotated by the rotation from the Geneva driving wheel 431, and the rotation angle is set to a predetermined angle. On the other hand, even if the Geneva driven vehicle 435 side rotates, the rotation is regulated by the Geneva driving vehicle 431 and is not transmitted to the Geneva driving vehicle 431 side. Accordingly, the Geneva drive wheel 431 and the Geneva driven vehicle 435 are non-reciprocal tooth profile transmission devices, and the Geneva driven vehicle 435 rotates by a predetermined angle (72 degrees) as the Geneva driving wheel 431 rotates, and the predetermined angle rotation is performed. In this case, a rotation restricting device for prohibiting the drive from the Geneva driven vehicle 435 to the Geneva driven vehicle 431 is configured.

Further, the claw 432 is formed such that the tip thereof is inclined toward the rotation direction of the Geneva drive wheel 431 and has a left-right asymmetric tooth profile. Therefore, when the Geneva drive wheel 431 rotates in the direction of the arrow in FIG. 3 and contacts the teeth 436 of the Geneva driven vehicle 435, the pawl 432 pushes the teeth 436 in the rotation direction of the Geneva driven vehicle 435. The drive wheel 435 is driven to rotate.
On the other hand, when the Geneva drive wheel 431 rotates in the reverse direction, the claw 432 contacts the tooth 437, but the tip of the claw 432 is formed with an inclined surface opposite to the side contacting the tooth 436. Thus, the claw 432 pushes the teeth 437 toward the center of rotation of the Geneva driven vehicle 435, so that the rotation cannot be transmitted to the Geneva driven vehicle 435.

[Configuration of train wheel after Geneva driven vehicle]
As shown in FIGS. 1 to 3, the pinion 438 of the Geneva driven vehicle 435 is engaged with the third wheel 44 and the pinion 441 of the third wheel 44 is engaged with the second wheel 45. Further, the second wheel 45 is provided with a second pinion 451, the second pinion 451 is engaged with the minute wheel 46, and the pinion 461 of the minute wheel 46 is engaged with the hour wheel 47.
A minute hand (not shown) is attached to the tip of the second pinion 451 of the second wheel 45. An hour hand (not shown) is attached to the tip of the hour wheel 47. These gears 44 to 46 are pivotally supported by the main plate 3 and the train wheel bridge 4.
When a second hand is provided, the second hand may be attached by placing the second hand or the second hand that rotates integrally with the fourth hand in the second hand 451 as in a normal timepiece. However, in this embodiment, since the second hand is not provided, a shaft member 48 that rotatably supports the second pinion 451 is provided inside the second pinion 451.

[Configuration of rotation detector]
The electronic timepiece 1 of the present embodiment includes a rotation detection device 70 (see FIG. 4) that detects the rotation of the rotation detection wheel 41.
The rotation detection device 70 detects whether the rotation detection wheel 41 has rotated a predetermined angle by detecting the spoke portion 412C of the rotation detection wheel 41 or the hole portion between the spoke portions 412C.
Specifically, the rotation detection device 70 uses a reflective or transmissive optical sensor including a light emitting element such as an LED and a light receiving element such as a phototransistor. In this embodiment, a reflection type optical sensor is used, and light is projected from the back cover side of the gear 412 and set so as to receive light reflected by the base plate 3 through the hole or light reflected by the spoke portion 412C. The rotation is detected by the output of the light receiving element.

More specifically, in the present embodiment, the light reflected by the base plate 3 through the hole of the rotation detection wheel 41 from the rotation detection device 70 is received and detected by the light receiving element. For this reason, when the spoke portions 412C are formed at intervals of 45 degrees in the rotation direction, the output of the light receiving element is equal to or greater than a predetermined value every time the rotation detection wheel 41 rotates 45 degrees. It changes to the ON state which becomes and the OFF state which becomes less than a predetermined value. Therefore, it is possible to detect whether or not the rotation detection wheel 41 has rotated 45 degrees by comparing the output of the light receiving element with a predetermined threshold value.
In general, a reflective optical sensor requires a predetermined distance from the light receiving / emitting surface of the optical sensor to the reflective surface. Therefore, compared with the case of reflecting by the spoke portion 412C, the reflection by the ground plane 3 has an advantage that the optical sensor can be disposed closer to the ground plane 3 and the timepiece 1 can be made thinner accordingly.

Note that the rotation detection device 70 is not limited to one that detects the movement amount (rotation angle) of the rotation detection wheel 41, and may be one that directly detects the movement amount of the rotor 30 or the rotor gear 31, for example. That is, the amount of movement of the rotor 30 or a member that rotates together with the rotor 30 may be detected from the rotor 30 before the spiral spring 426.
In addition to the optical sensor, various sensors capable of detecting the rotation amount (rotation angle) of the rotor 30 and the rotation detection wheel 41 such as a mechanical contact using a spring or a magnetic sensor can be used as the rotation detection device 70.
Accordingly, the rotation detection device 70 constitutes a drive amount detection means for detecting the drive amount of the rotor 30 and the rotor gear 31 that are driven bodies driven by the piezoelectric actuator 20.

[Configuration of time correction mechanism]
Also in the electronic timepiece 1 of the present embodiment, a time adjustment mechanism 80 that corrects the time by a crown operation is provided. This time adjustment mechanism 80 has been conventionally used, and includes a winding stem 81, a mandarin duck 82, a cannula 83, a thumb wheel 84, a small iron wheel 85, and the like that are rotated by a crown operation.
Then, the crown is pulled out and the crown wheel 84 and the cannula 83 are operated to rotate the crown with the wheel 84 engaged with the iron wheel 85, and the date wheel 46 engaged with the pinion 851 of the iron wheel 85 is operated by the crown. Rotate. Then, since the rotation of the Geneva driven vehicle 435 is restricted by the Geneva driving vehicle 431, the third wheel 44 and the second wheel 45 do not rotate, and the second kana 451 slips with respect to the second wheel 45. Rotates and corrects minute hand indication. Since the hour wheel 47 is also rotated by the rotation of the minute wheel 46, the hour hand instruction is also corrected in conjunction with the hour wheel.

[Circuit configuration of the watch]
Next, the circuit configuration of the timepiece 1 will be described with reference to FIG.
The driving circuit of the timepiece 1 includes an oscillation circuit 102, a frequency dividing circuit 103, and a control circuit 104 that are driven by a power source 101 including various batteries 2 such as a primary battery and a secondary battery.
The oscillation circuit 102 has a reference oscillation source such as a crystal resonator 6 and outputs an oscillation signal to the frequency dividing circuit 103.
The frequency divider 103 receives the oscillation signal output from the oscillation circuit 102 and outputs a clock reference signal (for example, a signal of 1 Hz) based on the oscillation signal.

The control circuit 104 counts the time based on the reference signal output from the frequency dividing circuit 103 and instructs the timepiece driving circuit 106 to output a timepiece driving signal conforming to the timepiece specification.
For example, when the timepiece 1 performs step hand movement every second as in the case where the timepiece 1 includes an hour hand, a minute hand, and a second hand, the control circuit 104 outputs a timepiece driving signal once per second. To instruct.
On the other hand, when the timepiece 1 is a two-hand timepiece having an hour hand and a minute hand as in the present embodiment, and the minute hand is sent twice every 20 seconds, the control circuit 104 sends the timepiece driving signal once every 20 seconds. The timepiece driving circuit 106 is instructed to output.

The control circuit 104 is connected to the rotation detection device 70 described above, and controls the operation of the timepiece driving circuit 106 using a detection signal output from the rotation detection device 70 as a trigger.
When the detection signal is output from the rotation detection device 70, that is, when the rotor 30 has moved a predetermined amount, the control circuit 104 controls the timepiece drive circuit 106 to stop outputting the drive signal. Control to stop the piezoelectric actuator 20 is performed.

  For example, when the second hand is stepped at intervals of 1 second, the control circuit 104 instructs the timepiece drive circuit 106 to output a drive signal every second. In this case, the rotation detection device 70 is set so as to detect that the rotor 30 rotates by a predetermined angle corresponding to the rotation of the second hand for one second, that is, 6 degrees. When detecting that the angle has been rotated, the control circuit 104 causes the timepiece driving circuit 106 to stop outputting the driving signal. For this reason, the piezoelectric actuator 20 is driven by an amount for moving the second hand by one second at intervals of one second.

  Further, when the minute hand is sent twice every 20 seconds as in a two-hand timepiece, the control circuit 104 instructs the timepiece drive circuit 106 to output a drive signal every 20 seconds. In this case, the rotation detection device 70 is set so as to detect that the rotor 30 rotates by a predetermined angle corresponding to the rotation of the minute hand for 20 seconds, that is, twice, and the rotation detection device 70 causes the rotor 30 to rotate. When detecting that the angle has been rotated, the control circuit 104 causes the timepiece driving circuit 106 to stop outputting the driving signal.

  The control circuit 104 is connected to an operation detection unit 109 that detects an operation of the time correction mechanism 80 such as a crown or a button. When the operation detection unit 109 detects a predetermined operation of the time adjustment mechanism 80, the operation detection unit 109 detects the operation and sends a predetermined signal to the control circuit 104. Based on the signal from the operation detection unit 109, the control circuit 104 instructs the timepiece drive circuit 106 to output a drive signal, that is, to start driving the piezoelectric actuator 20, and to stop outputting the drive signal, that is, to stop driving the piezoelectric actuator 20. To do.

For example, when the crown is pulled out to correct the time, it is necessary to stop the hand movement of the pointer. For this reason, when the operation detection unit 109 outputs a detection signal for the operation of pulling out the crown, the control circuit 104 outputs a control signal for stopping the driving of the piezoelectric actuator 20 to the timepiece drive circuit 106. On the other hand, when the operation detection unit 109 outputs a detection signal for pushing the crown, the control circuit 104 outputs a control signal for starting the driving of the piezoelectric actuator 20 to the timepiece driving circuit 106.
Therefore, the control circuit 104 constitutes drive control means for controlling the drive of the piezoelectric actuator 20.

The timepiece drive circuit 106 receives a control signal from the control circuit 104 and outputs a drive signal for the piezoelectric actuator 20. Specifically, the timepiece driving circuit 106 is driven by applying a driving voltage of a predetermined frequency to the piezoelectric element 22 of the piezoelectric actuator 20 by an AC signal (pulse signal).
The method for controlling the drive frequency of the piezoelectric actuator 20 is not particularly limited. For example, as disclosed in a patent document (Japanese Patent Laid-Open No. 2006-20445), the frequency of the drive signal supplied to the piezoelectric element 22 is set. Alternatively, the piezoelectric actuator 20 may be driven reliably by sweeping (changing) over a wide range including the driveable frequency range, or as disclosed in a patent document (Japanese Patent Laid-Open No. 2006-33912). A method of changing the frequency of the drive signal so that the phase difference between the frequency of the drive signal supplied to the element 22 and the detection signal obtained from the vibration state of the piezoelectric element 22 becomes a predetermined target phase difference suitable for driving may be used. Alternatively, a method of driving at a fixed frequency set for each temperature in advance may be used.

  In addition, a detection electrode that is not subject to voltage application is provided on the piezoelectric element 22 of the piezoelectric actuator 20, and the detection signal output from the detection electrode is fed back to the control circuit 104 to control the frequency of the drive signal. Good. With this detection signal, the control circuit 104 can confirm the driving state of the piezoelectric actuator 20 and feedback control the frequency of the driving signal.

The output of the piezoelectric actuator 20 is transmitted via the rotation transmission device 40 as described above.
The rotation transmission device 40 converts the rotational energy output from the piezoelectric actuator 20 into a movement amount suitable for time display and transmits it to a time display unit (pointer) 110 which is a time information display unit. In this embodiment, the rotor gear 31 to the rotation detection wheel 41 and the Geneva drive wheel 431 are speed-up wheel trains, and the Geneva driven wheel 435 to the third wheel 44, the second wheel 45, the sun wheel 46, the cylinder Since it is a reduction gear train up to the vehicle 47, the movement amount of the piezoelectric actuator 20 (rotation amount of the rotor 30) is changed to the movement amount of the time display at a predetermined acceleration / deceleration ratio.

[Details of piezoelectric actuator drive control method]
Next, details of drive control of the piezoelectric actuator 20 will be described with reference to the flowchart of FIG. 5 and FIGS.
As described above, under the control of the control circuit 104, the timepiece drive circuit 106 outputs a drive signal at intervals of 20 seconds. At this time, the timepiece drive circuit 106 first inputs a first drive signal (step S1). In this embodiment, as described above, an AC signal having a predetermined frequency is used as the drive signal, and the input energy is set by adjusting the input time of the drive signal (AC signal). For this reason, the first drive signal is set to an AC signal at the input time T1.

When the first drive signal is input, the control circuit 104 operates the rotation detection device 70 to determine whether or not the rotation detection wheel 41, that is, the rotor 30 has rotated the predetermined angle, that is, the driven body (rotor 30). It is determined whether or not the drive amount has reached the target drive amount (step S2).
As shown in FIG. 6, the control circuit 104 operates the rotation detection device 70 at the timing when the speed of the rotation detection wheel 41 decreases and the drive is stopped. That is, even if the input of the drive signal is stopped, the rotation detection wheel 41 continues to rotate due to inertia and slightly overruns. Accordingly, by operating the rotation detection device 70 after a predetermined time has elapsed after stopping the input of the drive signal, it is accurately determined whether or not the rotation detection vehicle 41 has reached a predetermined position after the rotation detection vehicle 41 has stopped driving. Can be detected. Since the overrun of the rotation detection wheel 41 is linked to the energy (input time) of the input drive signal, the longer the input time of the drive signal, the longer the predetermined time until the rotation detection device 70 is operated. There is.

If “No” is determined in step S2, that is, if the rotor 30 does not rotate to a predetermined angle only by inputting the first drive signal, the control circuit 104 outputs the second drive signal via the timepiece drive circuit 106. An input is made to the piezoelectric actuator 20 (step S3).
The second drive signal is a signal having an input time T2. This input time T2 is set to a time (for example, 1/4) shorter than T1, and the input energy of the second drive signal is smaller than the input energy of the first drive signal.

  Then, the control circuit 104 operates the rotation detection device 70 at a timing when the rotation detection wheel 41 rotated by the second drive signal stops, and determines whether or not the rotation detection wheel 41, that is, the rotor 30 has rotated to the predetermined angle. Determine (step S4).

  If “Yes” is determined in step S4, that is, as shown in FIG. 6, the rotor 30 does not rotate to a predetermined angle only by the first drive signal (detection result OFF), but the second drive signal is added. When the rotor 30 rotates to a predetermined angle by the input (detection result ON), the control circuit 104 ends the output of the drive signal.

  The control circuit 104 repeatedly executes the process from step S1 when performing the output process of the next drive signal performed at intervals of 20 seconds. In the present embodiment, the state shown in FIG. 6 is set as an ideal stable state. Therefore, in the case shown in FIG. 6, the input time T1 of the first drive signal is not corrected and the next time The drive process is performed.

On the other hand, if “No” is determined in step S4, the third drive signal is input to the piezoelectric actuator 20 as shown in FIG. 7 (step S5).
The third drive signal is a signal having an input time T3. This input time T3 is set to a time (for example, 1/4) shorter than T1, and the input energy of the third drive signal is smaller than the input energy of the first drive signal. Note that the input times T2 and T3 of the second and third drive signals are usually set to the same time, but may be different. For example, T2> T3 may be set.

Further, when the third drive signal is input, the control circuit 104 sets the input time T1 of the next first drive signal to be longer by the time Tβ than the previous time T1 (step S6).
This is because it can be determined that the input energy of the first drive signal is insufficient because the rotor 30 does not rotate to a predetermined angle even when the first drive signal and the second drive signal are input. Therefore, in step S6, the input energy of the next first drive signal is increased. Here, the time Tβ can be set arbitrarily, but usually the time Tβ may be about the same as T2 or T3.

Then, the control circuit 104 determines again whether or not the rotation detection wheel 41, that is, the rotor 30 has rotated to the predetermined angle by the input of the third drive signal (step S4).
As shown in FIG. 7, the rotor 30 does not rotate by a predetermined angle when the first drive signal and the second drive signal are input (detection result OFF), but the rotor 30 rotates by a predetermined angle when the third drive signal is input. If it is detected (detection result ON), the control circuit 104 ends the output of the drive signal.

  On the other hand, even if the third drive signal is input, if the rotation detection wheel 41, that is, the rotor 30 does not rotate to the predetermined angle, S4, 5, and 6 are repeatedly executed. That is, the input of the third drive signal and the time increase of the first drive signal are repeated until the rotor 30 rotates by a predetermined angle, and the output of the drive signal is terminated when it is determined “Yes” in step S4.

Further, as shown in FIG. 8, when the rotor 30 rotates by the predetermined angle only by the input of the first drive signal and it is determined “Yes” in step S2, the input energy of the first drive signal is excessive. .
Therefore, as shown in FIG. 9, the next input time T1 of the first drive signal is set shorter than the previous time T1 by a time Tα (step S7). Here, the time Tα can be set arbitrarily, but usually the time Tα may be approximately the same as T2 or T3.
If the rotation detection result is turned OFF by the input of the first drive signal with the input time shortened and turned ON by the input of the second drive signal, the stable control state of FIG. 6 is reached.
On the other hand, even if the new first drive signal becomes “Yes” in step S2, it is set to the first drive signal that is shorter by the time Tα. If this control is repeated, it will converge to the stable control state of FIGS.

[Effects of this embodiment]
According to this embodiment, the following effects can be achieved.
(1) The control circuit 104 sets the input time of the first drive signal short when the rotation detection wheel 41 has rotated to the set target drive amount only by inputting the first drive signal last time, If the rotation detection wheel 41 does not rotate to the set target drive amount even when the first drive signal and the second drive signal are input, the input time of the first drive signal is set longer.
For this reason, even if the load of the driven body driven by the piezoelectric actuator 20 fluctuates depending on the posture (orientation) of the electronic timepiece 1, the rotation is performed by inputting the second drive signal in addition to the first drive signal. The detection wheel 41 can be controlled to a stable state in which the detection wheel 41 rotates to the set target drive amount.

Accordingly, it is possible to prevent the input of the first drive signal with excessive energy and to save energy, and the drive time of the piezoelectric actuator 20 can be shortened, and the driven body with a short drive interval is continued like the second hand drive. Thus, it can be easily controlled even when driven.
That is, when the rotation detection wheel 41 rotates to the target angle (reach the target drive amount) with only the first drive signal, it can be determined that the input energy is excessive. Even if the input energy is excessive, by providing the rotation regulating device 43 such as a Geneva gear device, the driving amount of the pointer can be regulated at a constant angle, but wasteful power is consumed. For this reason, especially in a battery-powered wristwatch, the increase in power consumption shortens the duration and decreases convenience.
On the other hand, in this embodiment, since energy saving can be achieved, the duration time can be extended even in a wristwatch.

  Further, if the rotation detection wheel 41 does not rotate to the target angle even if the first and second drive signals are input, the third drive signal (correction signal) is input until the target angle is reached, and the rotation detection wheel 41 can rotate reliably. At the same time, since the input time of the next first drive signal is lengthened, the number of drive signals input until the rotation detection wheel 41 reaches the target angle can be reduced from the next time, and the drive control time is shortened accordingly. it can. Therefore, when the driven body is driven at a constant time interval, the time interval can be shortened. For example, step movement of the second hand at 1 second intervals can be easily realized.

(2) The control circuit 104 determines whether or not the rotation detection wheel 41 has rotated to the target angle by the rotation detection device 70 after a predetermined time has elapsed after the piezoelectric actuator 20 has finished inputting the first drive signal. For this reason, it is possible to detect the drive amount of the driven body with high accuracy.
In other words, if the drive amount is detected while the piezoelectric actuator 20 is being driven, the detected drive amount will deviate from the actual drive amount because there is an overrun due to a detection time lag or inertia of the drive system. For this reason, it is difficult to improve the accuracy of drive control.
On the other hand, in the present invention, after the first drive signal is input, the rotation detection is performed in anticipation of the timing when the rotation detection wheel 41 stops. In addition, the drive amount can be determined.

(3) In this embodiment, every time control (step S5) for inputting the third drive signal is performed, the input time of the first drive signal is increased. Sometimes, the updated first drive signal can be input to the piezoelectric actuator 20. For this reason, it can be driven to the target drive amount more quickly, and the step hand movement of the pointer can be stabilized.

(4) After the piezoelectric actuator 20 is driven, the rotation detector 70 detects that the rotation detection wheel 41 has rotated a predetermined angle (45 degrees) and the drive of the piezoelectric actuator 20 is stopped. Even if the Geneva driven vehicle 431 overruns due to the damping vibration of the rotor 30 or the inertia of the rotor 30 or the like, the rotation of the Geneva driven vehicle 435 has a margin after the engagement between the claw 432 and the Geneva driven vehicle 435 is released. Therefore, the Geneva driven vehicle 435 is intermittently driven, and the rotation angle thereof can always be constant (72 degrees in the present embodiment). For this reason, the amount of movement of the pointer to which the rotation of the Geneva driven vehicle 435 is transmitted can always be constant, and the position accuracy of the pointer for stepping can be ensured.

(5) Since the piezoelectric element 22 is formed in a rectangular plate shape, the piezoelectric drive device 10 can be made thinner.

(6) Since the rotation detection device 70 detects the movement amount of the rotation detection wheel 41, that is, the rotor 30, the movement amount of the pointer can also be set accurately. The reason is as follows.
Since the vibration body 21 of the piezoelectric actuator 20 and the rotor 30 transmit torque by friction, it is difficult to accurately set the rotation amount of the rotor 30 depending on the driving time of the piezoelectric actuator 20. In this embodiment, the amount of movement of the rotation detection wheel 41 that is driven directly with the rotor 30 is detected by the rotation detection device 70, and the drive is performed when the rotation detection device 70 detects that the rotor 30 has moved a predetermined amount. Since it is stopped, the rotor 30, that is, the pointer can be moved accurately. Furthermore, by providing the rotation detection wheel 41 between the rotor 30 and the elastic device 42 (particularly the spiral spring 426), the rotational energy of the rotor 30 is in the stage before being accumulated in the spiral spring 426 as elastic energy. The rotation of the rotor 30 can be detected. Therefore, the rotation of the rotor 30 according to the driving of the piezoelectric actuator 20 can be detected more accurately, and the rotor 30 and the rotor 30 and the rotation detecting wheel 41 can be compared with the case where the rotation detection wheel 41 is provided on the rear side (opposite the rotor). The pointer can be moved more accurately.

[Modification of the present invention]
It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, the configuration of the piezoelectric actuator is not limited to a substantially rectangular plate shape, but may be a substantially rhomboid plate shape or a substantially parallelogram plate shape. Good. Furthermore, a piezoelectric actuator formed in a truss shape may be used. In other words, the specific configuration of the piezoelectric actuator may be set as appropriate in implementation.

  The configuration of the drive amount detection means is not limited to that of the above embodiment. For example, a detection electrode may be provided on the piezoelectric actuator 20, and the drive amount of the piezoelectric actuator 20 may be detected using a detection signal output from the detection electrode, or other detection means may be used.

  The driving target (driven body) is not limited to a gear that is rotationally driven, but may be a movable body that can move linearly, such as a slider that moves linearly via the rotor 30 or the like.

  Further, the piezoelectric driving device of the present invention is not limited to the one applied to the electronic timepiece 1 of the embodiment. That is, the electronic device adopting the piezoelectric driving device of the present invention is not limited to an electronic timepiece such as a wristwatch, a table clock, and a wall clock, but the present invention can be applied to various electronic devices, and particularly downsizing is required. Suitable for portable electronic devices. Here, examples of various electronic devices include a phone having a clock function, a mobile phone, a non-contact IC card, a personal computer, a personal digital assistant (PDA), a camera, and the like. The present invention can also be applied to electronic devices such as a camera without a clock function, a digital camera, a video camera, and a mobile phone with a camera function. When applied to an electronic apparatus having these camera functions, the present invention can be used to drive a lens focusing mechanism, a zoom mechanism, an aperture adjustment mechanism, and the like. In addition, it is used for measuring instrument meter pointer driving mechanisms, movable toy and micro robot driving mechanisms, instrument panel driving mechanisms for automobile and other instrument panels, piezoelectric buzzers, printer inkjet heads, ultrasonic motors, etc. You may use the piezoelectric drive device of invention. In short, the present invention can be applied to various electronic devices having a driving target driven by a piezoelectric actuator. In particular, the piezoelectric drive device of the present invention is widely used as a drive source that requires anti-magnetism because it has excellent anti-magnetic performance compared to a stepping motor or the like.

In the above-described embodiment, the piezoelectric actuator 20 is used for driving the hands of the electronic timepiece 1. However, the present invention is not limited thereto, and may be used for driving a calendar mechanism such as a date wheel of the electronic timepiece 1. In this way, the electronic timepiece 1 can be made thinner by replacing the stepping motor that drives the hands and date wheel with a piezoelectric actuator, and the piezoelectric actuator is more magnetically affected than the stepping motor. Since it is not easily received, it is possible to achieve high magnetization resistance of the electronic timepiece.
Further, in a mechanism of a timepiece clock, for example, a timepiece clock in which a doll moves according to time, a piezoelectric actuator may be used as a driving source of the doll.

The best configuration, method and the like for carrying out the present invention have been disclosed in the above description, but the present invention is not limited to this. That is, the invention has been illustrated and described primarily with respect to particular embodiments, but may be configured for the above-described embodiments without departing from the scope and spirit of the invention. Various modifications can be made by those skilled in the art in terms of materials, quantity, and other detailed configurations.
Therefore, the description limited to the shape, material, etc. disclosed above is an example for easy understanding of the present invention, and does not limit the present invention. The description by the name of the member which remove | excluded the limitation of one part or all of such restrictions is included in this invention.

  DESCRIPTION OF SYMBOLS 1 ... Electronic timepiece, 10 ... Piezoelectric drive device, 20 ... Piezoelectric actuator, 21 ... Vibrating body, 22 ... Piezoelectric element, 30 ... Rotor, 31 ... Rotor gear, 40 ... Rotation transmission device, 41 ... Rotation detection wheel, 43 ... Rotation Restriction device, 70 ... rotation detection device, 80 ... time correction mechanism, 101 ... power source, 104 ... control circuit, 106 ... clock drive circuit, 110 ... time display unit (pointer).

Claims (5)

A piezoelectric actuator that has a piezoelectric element and includes a vibrating body that vibrates by supplying a driving signal to the piezoelectric element, and transmits the vibration of the vibrating body to a driven body;
Drive amount detection means for detecting whether or not the drive amount of the driven body has reached a preset value;
Drive control means for controlling supply of a drive signal to the piezoelectric actuator,
The drive amount detection means detects the drive amount of the driven body every time a drive signal is supplied to the piezoelectric actuator,
The drive control means includes
After the first drive signal is input to the piezoelectric actuator, when the drive amount of the driven body reaches the set value, the input energy of the first drive signal to be input next is smaller than the previous input energy. And
After the first drive signal is input to the piezoelectric actuator, if the drive amount of the driven body does not reach the set value, a second drive signal having an input energy smaller than the input energy of the first drive signal is output. Input,
When the drive amount of the driven body reaches the set value by the input of the second drive signal, the input energy of the first drive signal to be input next becomes the same input energy as the first drive signal input last time. Maintain,
When the driving amount of the driven body does not reach the set value due to the input of the second driving signal, a third driving signal having an input energy smaller than the input energy of the first driving signal is supplied to the driven body. A piezoelectric driving device characterized in that input is repeated until the driving amount reaches the set value, and the input energy of the first driving signal to be input next is made larger than the input energy of the first driving signal input last time. The piezoelectric drive device according to claim 1,
The piezoelectric drive device, wherein the drive control means controls the input energy by controlling a drive time with a voltage of a drive signal constant. In the piezoelectric drive device according to claim 1 or 2,
The drive control means includes
After the drive signal is input to the piezoelectric actuator, it is determined whether the drive amount of the driven body has reached the set value by the drive amount detection means after a predetermined time has elapsed,
The piezoelectric drive device according to claim 1, wherein the predetermined time is longer than a time from when the input of the drive signal to the piezoelectric actuator is stopped until the drive system including the driven body is stopped. A piezoelectric actuator that has a piezoelectric element and includes a vibrating body that vibrates by supplying a driving signal to the piezoelectric element, and transmits the vibration of the vibrating body to a driven body;
Drive amount detection means for detecting whether or not the drive amount of the driven body has reached a preset value;
A drive control means for controlling the supply of a drive signal to the piezoelectric actuator, and a method for controlling a piezoelectric drive device comprising:
After the first drive signal is input to the piezoelectric actuator, when the drive amount of the driven body reaches the set value, the input energy of the first drive signal to be input next is smaller than the previous input energy. And
After the first drive signal is input to the piezoelectric actuator, if the drive amount of the driven body does not reach the set value, a second drive signal having an input energy smaller than the input energy of the first drive signal is output. Input,
When the drive amount of the driven body reaches the set value by the input of the second drive signal, the input energy of the first drive signal to be input next becomes the same input energy as the first drive signal input last time. Maintain,
When the driving amount of the driven body does not reach the set value due to the input of the second driving signal, a third driving signal having an input energy smaller than the input energy of the first driving signal is supplied to the driven body. The piezoelectric drive device is characterized in that the drive energy is repeatedly input until the set value reaches the set value, and the input energy of the first drive signal to be input next is made larger than the input energy of the first drive signal input last time. Control method.   An electronic timepiece comprising: the piezoelectric driving device according to any one of claims 1 to 3; and a time information display unit driven by the piezoelectric driving device.

Images