JP5197267B2 - Drive device, control method therefor, and electronic apparatus - Google Patents

Description

  The present invention relates to a driving device including a vibration wave motor that excites a vibrating body by applying an AC voltage to an electromechanical energy conversion element and applies a driving force due to friction to a moving body pressed by the vibrating body, and the driving device The present invention relates to a control method and an electronic apparatus including the driving device.

  Conventionally, a vibration wave motor (ultrasonic motor) that drives an object by vibration generated in a vibrating body has been developed and put into practical use. A vibration wave motor is a motor configured to generate high-frequency vibrations in a piezoelectric element 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. is there.

  FIG. 10 is a cross-sectional view illustrating a configuration example of a vibration wave motor according to a conventional example.

  In FIG. 10, the piezoelectric element group 201 is polarized to two poles, and the piezoelectric elements are stacked and fired in multiple layers. The vibrator 202 is welded to the piezoelectric element group 201 and amplifies the vibration generated in the piezoelectric element group 201. As is well known, a traveling wave is generated in the vibrator 202 or a standing wave is generated by adjusting the temporal phase of the driving voltage applied to one pole and the other pole of the piezoelectric element group 201. Is possible.

  The flange 203 is fixed to the rotor 204, and the rotor 204 is provided integrally with the spring case 205. The collar 203 is pressed against the vibrator 202 by a pressure spring 206 held by a spring case 205.

  A detent 213 is press-fitted into the shaft 210 and engaged with the detent 213 and the rotor 204. The shaft 210 is rotatably supported by a bearing A 208 and a bearing B 209 fixed to the case 212. The flange 211 is fixed to the case 212 and fixed to a device that drives the vibration wave motor.

  In the vibration wave motor configured as described above, the flange 203 is rotated by the traveling wave generated by the vibration of the vibrator 202, and the rotational force is transmitted from the rotor 204 to which the flange 203 is fixed to the detent 213. The shaft 210 into which the stopper 213 is press-fitted rotates.

  FIG. 11 is a diagram illustrating the relationship between the frequency of the drive voltage supplied to the vibration wave motor and the rotation speed of the vibration wave motor.

  In FIG. 11, the vibration wave motor has the characteristics as shown in the figure, and the rotational speed of the vibration wave motor is controlled using this characteristic. That is, when starting the vibration wave motor, the drive voltage frequency at the time of starting is normally set to a frequency fs sufficiently higher than the resonance frequency fM.

  When the frequency is gradually lowered from the frequency fs, the vibration wave motor starts moving at the frequency f1. As the frequency is further lowered, the rotational speed of the vibration wave motor gradually increases until reaching the rotational speed corresponding to the corresponding frequency.

  On the other hand, the rotational speed of the vibration wave motor is detected, and if the detected rotational speed reaches the target rotational speed Na, the decrease in frequency is stopped. When stopping the vibration wave motor, on the contrary, the frequency is gradually increased, the rotation speed is decreased, and the vibration wave motor is smoothly stopped.

  In the vibration wave motor, the vibrator 202 and the flange 203 are always pressurized, and a frictional force is generated between them. Therefore, the vibration wave motor is characterized by having a self-holding force when stopped.

  The material of the vibrator 202 of the vibration wave motor shown in FIG. 10 is a SUS material, the surface that contacts the flange 203 is subjected to a nitriding process, and the material of the flange 203 is also a SUS material. Further, the contact surfaces of the vibrator 202 and the flange 203 are both polished.

  The vibration wave motor configured as described above has a high holding torque immediately after the rotation is stopped, and the holding torque gradually decreases when left as it is, and may decrease from 1/4 to 1/6 compared to immediately after the stop. is there.

  Here, in a device that takes out the driving force of the output shaft (drive shaft) connected to the motor shaft of the vibration wave motor via a gear and uses the driving force, the user manually moves the vibration wave motor from the output shaft side. Consider the case of rotating.

  In this case, since the vibration wave motor has a self-holding force as described above, the rotation of the gear attached to the motor shaft of the vibration wave motor is restricted. In particular, when the self-holding force immediately after the stop is high, when trying to manually rotate the vibration wave motor from the output shaft, the gear tooth skip between the gear attached to the motor shaft and the gear meshing with the gear. There is a problem that chipping of the tooth surface occurs. Note that gear tooth skipping is a phenomenon in which the gear teeth fly to the tooth next to the tooth to be engaged with the counterpart gear.

In order to solve the above problem, when the vibration wave motor is manually driven from the outside (driven in the manual manual mode), a drive voltage is applied to the piezoelectric element so as to generate a standing wave to the vibrator. A technique for reducing the holding torque has been proposed (see, for example, Patent Document 1).
JP 2007-189777 A

  However, the technique disclosed in Patent Document 1 has a problem that power is wasted because the driving state of the vibration wave motor is always monitored when the vibration wave motor is stopped. Furthermore, in the case of a vibration wave motor, the holding torque decreases rapidly as the stop time is lengthened, so that it may not be necessary to generate a standing wave in the vibrator. Even in such a case, if a standing wave is generated, more power is wasted. In particular, in recent years, electronic devices such as printers and pan / tilt cameras have become mobile, and battery driving is therefore essential. Therefore, power consumption reduction during standby is a major issue.

  An object of the present invention is to provide a drive device that can reduce power consumption of a vibration wave motor at the time of stopping, and further prevent occurrence of gear skipping or tooth surface chipping, a control method therefor, and an electronic device. There is to do.

  In order to achieve the above object, a drive device according to claim 1 is generated by an electro-mechanical energy conversion element, a vibrating body that vibrates by application of a driving voltage to the electro-mechanical energy conversion element, and vibration of the vibrating body. A vibration wave motor having a moving body driven by a traveling wave, a control means for controlling application of the drive voltage, and a movement detection means for detecting movement of a drive target portion to which the driving force of the vibration wave motor is transmitted And when the movement detection unit detects the movement of the drive target unit when the drive voltage is not applied for a predetermined time or less, the control unit may include the electro-mechanical energy conversion element. Apply a driving voltage to generate a standing wave in the vibrating body, and control so as not to generate the standing wave when the driving voltage is not applied for a predetermined time. And features.

  An electronic device according to a fifth aspect includes the drive device according to any one of the first to fourth aspects.

  According to a seventh aspect of the present invention, there is provided a control method for a driving apparatus comprising: an electro-mechanical energy conversion element; a vibrating body that vibrates when a driving voltage is applied to the electro-mechanical energy conversion element; and a traveling wave generated by vibration of the vibrating body In a control method of a drive device comprising a vibration wave motor having a movable body to be driven, a detection step of detecting a movement of a drive target portion to which a drive force of the vibration wave motor is transmitted, and application of the drive voltage If the movement of the drive target part is detected by the detection step when there is no state for a predetermined time or less, the drive voltage is applied to the electromechanical energy conversion element, and a standing wave is applied to the vibrating body. And a control step for preventing the standing wave from being generated when the driving voltage is not applied for a predetermined time.

  According to the drive device of the present invention, it is possible to reduce the power consumption of the vibration wave motor at the time of stopping, and to prevent the occurrence of gear tooth skipping and tooth surface chipping.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an upper perspective view of a pan / tilt camera including a vibration wave motor according to an embodiment of the present invention. FIG. 2 is a lower perspective view of the pan / tilt camera including the vibration wave motor according to the embodiment of the present invention.

  1 and 2, a pan / tilt camera 100 includes the driving device of the present invention, and the driving device drives a camera unit 102 that is a driving target unit in the pan and tilt directions.

  The pan / tilt camera 100 includes a base 101, a camera unit (drive target unit) 102, a tilt driving vibration wave motor 103, a tilt motor pinion gear (transmission mechanism) 104, and a tilt gear (transmission mechanism) 105.

  The pan / tilt camera 100 also includes a tilt unit encoder sensor (movement detecting means) 106 and a tilt unit encoder scale 107.

  Further, the pan / tilt camera 100 includes a pan driving vibration wave motor 110, a pan motor pinion gear (transmission mechanism) 111, a pan gear (transmission mechanism) 112, a pan section encoder sensor (movement detecting means) 113, and a pan section encoder scale 114. ing.

  In the pan / tilt camera 100, the camera unit 102 provided on the base 101 rotates in a tilt direction (B1 direction and B2 direction in FIG. 1) and a pan direction (D1 direction and D2 direction in FIG. 2) to perform an imaging operation. The pan unit 115 includes a camera unit 102 and a tilt driving unit described later. The base 101 rotates freely with respect to the pan unit 115 by driving the pan driving vibration wave motor 110.

  The camera unit 102 is equipped with a tilt motor shaft (not shown). A tilt driving vibration wave motor (hereinafter referred to as vibration wave motor) 103 generates a driving force for rotating the camera unit 102 in the tilt direction.

  A panning vibration wave motor (hereinafter referred to as vibration wave motor) 110 rotates the camera unit 102 provided on the base 101 in the pan direction in order to generate a driving force that rotates the base 101 in the pan direction. The configuration of the main parts of the vibration wave motors 103 and 110 will be described later with reference to FIG.

  A tilt motor pinion gear (hereinafter, pinion gear) 104 is fixed to the motor shaft of the vibration wave motor 103. The tilt gear 105 is attached to the tilt motor shaft and meshes with the pinion gear 104.

  The tilt unit encoder scale (hereinafter referred to as encoder scale) 107 includes a slit unit (not shown) and is attached to a tilt motor shaft. The tilt unit 105 is rotated in the direction of arrows B1 and B2 together with the tilt gear 105, that is, along with the rotation of the camera unit 102. Rotate to.

  A tilt unit encoder sensor (hereinafter referred to as an encoder sensor) 106 reads the slit portion of the encoder scale 107 to detect the rotation state of the encoder scale 107.

  When the vibration wave motor 103 rotates in the direction of arrow A1 in FIG. 1 (the direction of rotation in the plane parallel to the base surface), the camera unit 102 moves in the direction of arrow B1 (base) due to the gear engagement between the pinion gear 104 and the tilt gear 105. Rotate in a direction perpendicular to the surface).

  On the other hand, when the vibration wave motor 103 rotates in the direction of arrow A2 in FIG. 1 (the direction of rotation in the plane parallel to the base surface), the camera unit 102 moves in the direction of arrow B2 due to the gear engagement between the pinion gear 104 and the tilt gear 105. Rotate in the direction of rotation in a plane perpendicular to the base surface.

  Here, when the user tries to manually rotate the camera unit 102 in the arrow B1 direction or the arrow B2 direction, the rotational force is transmitted to the tilt gear 105 and further to the pinion gear 104 engaged with the tilt gear 105. The

  Since the tilt gear 105 has a structure that is decelerated with respect to the pinion gear 104, the rotational torque generated by the tilt gear 105 is reduced by the reduction ratio on the pinion gear 104 axis.

  The maximum force for the user to rotate the camera unit 102 is obtained by multiplying the holding torque of the vibration wave motor 103 by the reduction ratio. However, immediately after the vibration wave motor 103 is continuously driven, the holding torque becomes very large, and the rotational force also becomes large.

  Naturally, since the drive transmission force generated between the tilt gear 105 and the pinion gear 104 is also increased, there is a possibility that the tooth surface of the gear is chipped or tooth skipping occurs. A technique for avoiding the above problem will be described later.

  A pan motor pinion gear (hereinafter, pinion gear) 111 is fixed to the motor shaft of the vibration wave motor 110. The pan gear 112 is attached to the base 101 and meshes with the pinion gear 111.

  The pan part encoder scale (hereinafter referred to as encoder scale) 114 includes a slit part (not shown), and rotates in the directions of arrows D1 and D2 as the pan unit 115 rotates. A pan encoder sensor (hereinafter referred to as an encoder sensor) 113 reads the slit portion of the encoder scale 114 to detect the rotation state of the encoder scale 114.

  When the vibration wave motor 110 rotates in the direction of the arrow C1 in FIG. 2 (the direction of rotation in the plane perpendicular to the base surface), the pan unit 115 moves in the direction of the arrow D1 (base) due to the meshing of the pinion gear 111 and the pan gear 112. Rotate in a direction parallel to the surface).

  On the other hand, when the vibration wave motor 110 rotates in the direction of the arrow C2 in FIG. 2 (the direction of rotation in the plane perpendicular to the base surface), the pan unit 115 moves in the direction of the arrow D2 due to the engagement of the pinion gear 111 and the pan gear 112. Rotate in the direction of rotation in a plane parallel to the base surface.

  Here, when the user tries to manually rotate the pan unit 115 in the direction of arrow D1 or arrow D2, the rotational force is transmitted to the pan gear 112 and further to the pinion gear 111 engaged with the pan gear 112. Is done.

  Since the pan gear 112 has a structure that is decelerated with respect to the pinion gear 111, the rotational torque generated by the pan gear 112 is reduced by the reduction ratio on the pinion gear 111 axis.

  The maximum force for the user to rotate the pan unit 115 is obtained by multiplying the holding torque of the vibration wave motor 110 by the reduction ratio. However, immediately after the vibration wave motor 110 is continuously driven, the holding torque becomes very large, so that the rotational force becomes very large.

  Further, since the drive transmission force generated between the pan gear 112 and the pinion gear 111 is also increased, there is a possibility that the gear tooth surface is chipped or skipped. A technique for avoiding the above problem will be described later.

  FIG. 3 is a block diagram showing the configuration of the drive control system of the vibration wave motor.

  In FIG. 3, the drive control system of the vibration wave motor constitutes the drive device of the present invention.

  The drive control system of the vibration wave motor includes a control unit (control means) 20, a comparator 21, a gain control circuit 22, a voltage control oscillator (control means) 23, a drive pulse generator 24, a driver A25, a driver B26, a power supply 27, A speed detector 28 is provided.

  Two drive control systems are provided corresponding to each of the vibration wave motor 103 and the vibration wave motor 110, but only one system is shown in FIG. 3 for convenience.

  The control unit 20 is composed of a computer that controls each unit and performs control including setting of the target rotational speed of the vibration wave motor 103 (110). Based on the program, each control unit shown in FIGS. The process shown in the flowchart is executed.

  The comparator 21 includes the target rotational speed set by the control unit 20 and the rotational speed (rotational speed) of the vibration wave motor 103 (110) detected by the speed detector 28 based on the reading value of the encoder sensor 106 (113). And outputs a signal corresponding to the difference.

  The gain control circuit 22 controls the gain (integral gain, proportional gain, etc.) based on the output signal of the comparator 21.

  The voltage controlled oscillator 23 generates a pulse signal (standing wave) whose gain is controlled based on the output signal of the gain control circuit 22.

  The drive pulse generator 24 generates a drive pulse signal to distribute the drive phase of the vibration wave motor 103 (110) to the A phase and the B phase. In the case of a traveling wave, the drive pulse signal is generated with a 90 ° phase shift between the A phase and the B phase.

  The driver A25 converts the A-phase drive pulse signal into a sine wave signal and outputs it as a drive voltage to the piezoelectric element of the vibration wave motor 103 (110). The driver B26 converts the B-phase drive pulse signal into a sine wave signal and outputs it as a drive voltage to the piezoelectric element of the vibration wave motor 103 (110).

  The power source 27 supplies power to the driver A25 and the driver B26. A rotation output is taken out from the motor shaft of the vibration wave motor 103 (110).

  FIG. 4 is a cross-sectional view showing the internal structure of the vibration wave motor shown in FIGS.

  In FIG. 4, the vibration wave motor 103 (110) includes a piezoelectric element (electro-mechanical energy conversion element) 7, a vibrator (vibrating body) 2, a flange 3, a rotor 4 (moving body), a spring case 5, and a pressure spring 6. , Bearing A8, bearing B9, shaft 10, and rotation preventing member 13 are provided.

  The vibration wave motor 103 (110) applies an AC voltage to a piezoelectric element, which is an electromechanical energy conversion element, and excites the vibrator 2 to generate a traveling wave, thereby pressing the vibrator 2 in pressure contact. The flange 3 is rotated, and the rotor 4 into which the flange 3 is press-fitted is rotated.

  The rotation of the rotor 4 is transmitted to the anti-rotation member 13, and the shaft 10 into which the anti-rotation member 13 is press-fitted is rotated.

  Here, the vibrator 2 is made of a SUS material, and the contact surface P that comes into contact with the brim 3 is subjected to a chipping process. The collar 3 is also made of SUS material, and the collar 3 and the contact surface P of the vibrator 2 are each polished.

  Thus, in the vibration wave motor 103 (110) in which the metals are in pressure contact with each other, the holding torque immediately after the rotation is much higher than that in the case where the metal is left for a long time. Depending on the vibration wave motor, the holding torque immediately after the rotation may be reduced by half in about 10 minutes and reduced to about 1/4 in one hour.

  Next, a drive control method for avoiding the above-described problem of the vibration wave motor mounted on the pan / tilt camera of the present embodiment will be described with reference to FIGS.

  In the present embodiment, monitoring mode 1 and monitoring mode 2 are provided as monitoring modes for monitoring the output of encoder sensor 106 (113).

  First, the monitoring mode 1 will be described. Further, since the vibration wave motor 103 and the vibration wave motor 110 perform similar control, the vibration wave motor 103 will be described in the present embodiment.

  The monitoring mode 1 is a mode when the power source (not shown) of the pan / tilt camera 100 is turned off by the user.

  FIG. 5 is a flowchart showing the procedure of the vibration wave motor drive control process in the monitoring mode 1, which is executed by the vibration wave motor drive control system of FIG.

  This process is executed under the control of the control unit 20 in FIG.

  Since the current flows through the control unit 20 and the like even when the user turns off the power, the output of the encoder sensor 106 can be detected. When the user turns off the power of the pan / tilt camera 100, the monitoring mode 1 is started (step S1).

  The control unit 20 measures a stop time from when the vibration wave motor 103 was last stopped by a timer (not shown), and determines whether or not the stop time is equal to or less than a predetermined time (step S2). The predetermined time is set to T.

  When the stop time is equal to or shorter than the predetermined time T (YES in step S2), the controller 20 checks whether the encoder pulse is detected by the speed detector 28 as the encoder sensor 106 reads the slit portion of the encoder scale 107. (Step S3).

  When the stop time is longer than the predetermined time T (when the stop time exceeds the predetermined time T) (NO in step S2), the monitoring mode 1 is terminated (step S6) and is completely turned off (step S8). That is, the monitoring mode 1 is terminated and the power is not consumed. Then, this process ends.

  If the user does not manually rotate the camera unit 102, an encoder pulse is not detected (NO in step S3), so that the monitoring mode 1 is in a standby state.

  Since the encoder pulse is detected when the user manually rotates the camera unit 102 (YES in step 3), the control unit 20 generates a pulse signal corresponding to the standing wave from the voltage controlled oscillator 23. (Step S4).

  That is, the control unit 20 applies a driving voltage to the piezoelectric element 7 via the driver A25 and the driver B26 so that the vibrator 2 of the vibration wave motor 103 generates a standing wave.

  The control unit 20 determines whether or not encoder pulses are continuously generated from the encoder sensor 106 (step S5).

  When encoder pulses are continuously generated from the encoder sensor 106 (YES in step S5), the control unit 20 continues to generate a pulse signal corresponding to the standing wave from the voltage controlled oscillator 23.

  If the encoder sensor 106 no longer receives an encoder pulse (NO in step 5), the control unit 20 stops generating a pulse signal corresponding to the standing wave from the voltage controlled oscillator 23 (step S7).

  Next, the monitoring mode 2 will be described. Since the vibration wave motor 103 and the vibration wave motor 110 perform the same control as in the monitoring mode 1, the vibration wave motor 103 will be described in the present embodiment.

  The monitoring mode 2 is a control mode when the power of the pan / tilt camera 100 is ON and the vibration wave motor 103 is stopped.

  FIG. 6 is a flowchart showing the procedure of the vibration wave motor drive control process in the monitoring mode 2, which is executed by the vibration wave motor drive control system of FIG.

  This process is executed under the control of the control unit 20 in FIG.

  When the vibration wave motor 103 is stopped, the monitoring mode 2 is started (step S10). First, the control unit 20 determines whether or not a drive command is transmitted to the vibration wave motor 103 (step S11).

  If there is a drive command (YES in step S11), the vibration wave motor 103 is driven according to the drive command (step S12). When no drive command is transmitted (NO in step S11), the control unit 20 measures the stop time from when the vibration wave motor 103 was last stopped by a timer (not shown), and the stop time is a predetermined time. It is determined whether or not T or less (step S13).

  When the stop time is equal to or shorter than the predetermined time T (YES in step S13), the controller 20 determines whether the encoder pulse is detected by the speed detector 28 as the encoder sensor 106 reads the slit portion of the encoder scale 107. Check (step S14).

  Since the encoder pulse is not detected unless the user manually rotates the camera unit 102 (NO in step S14), the monitoring mode 2 is continued as it is.

  Since the encoder pulse is detected when the user manually rotates the camera unit 102 (YES in step S14), the control unit 20 generates a pulse signal corresponding to the standing wave from the voltage controlled oscillator 23. (Step S15).

  That is, the control unit 20 applies a driving voltage to the piezoelectric element 7 via the driver A25 and the driver B26 so as to generate a standing wave for the vibrator 2 of the vibration wave motor 103. Subsequently, the control unit 20 determines whether or not a drive command is transmitted (step S16).

  When the drive command is transmitted (YES in step S16), the control unit 20 immediately stops the generation of the standing wave and simultaneously transmits a warning signal (not shown) (step S17). Further, the vibration wave motor 103 is driven according to the drive command. After driving, the monitor mode 2 is entered again, and it is determined whether or not a drive command is transmitted in step S11.

  When the drive command is not transmitted (NO in step S16), the control unit 20 determines whether encoder pulses are continuously generated from the encoder sensor 106 (step S18).

  When encoder pulses are continuously generated from the encoder sensor 106 (YES in step S18), the control unit 20 continues to generate a pulse signal corresponding to the standing wave from the voltage controlled oscillator 23.

  If the encoder sensor 106 no longer receives an encoder pulse (NO in step 18), the control unit 20 stops generating a pulse signal corresponding to the standing wave from the voltage controlled oscillator 23 (step S19). Then, the monitor mode 2 is entered again, and the presence or absence of a drive command is determined in step S11.

  On the other hand, when the stop time is longer than the predetermined time T (NO in step S13), the monitoring mode 2 is terminated. That is, the control unit 20 does not generate a standing wave. Further, the encoder sensor 106 is turned off (the operation of the encoder sensor 106 is stopped), and the slit portion of the encoder scale 107 is not read.

  FIG. 7 is a diagram showing the relationship between the drive frequency supplied to the vibration wave motor of FIG. 4, the rotational speed of the vibration wave motor, and the current value supplied to the vibration wave motor.

  In FIG. 7, the horizontal axis indicates the drive frequency (f) supplied to the vibration wave motor 103, and the vertical axis indicates the rotation speed (N) and current (A) of the vibration wave motor 103 (the rotation speed is a solid line, current). Values are shown as dotted lines).

  An arrow pointing left from the starting frequency fs when starting the vibration wave motor 103 indicates a start-up frequency sweep when the drive voltage frequency is gradually lowered from the starting frequency fs. The operating range of the vibration wave motor 103 is from the frequency fM to the minimum frequency f1 at which the vibration wave motor 103 operates.

  The standing wave generated from the voltage controlled oscillator 23 in step S4 of FIG. 5 and step S15 of FIG. 6 uses a frequency in the vicinity of the frequency ft at which the current value is the lowest. At this time, the vibration wave motor 103 may be used with a voltage slightly lower than the voltage for normal driving.

  8 is a diagram showing a pulse signal representing a standing wave output from the drive pulse generator in FIG. 3, and FIG. 9 shows a pulse signal representing a traveling wave output from the drive pulse generator in FIG. FIG.

  In FIG. 8, when an encoder pulse is output from the encoder sensor 106, a pulse signal representing a standing wave is sent from the voltage controlled oscillator 23 via the drive pulse generator 24 in synchronization with the rising edge of the encoder pulse. B is input in the same phase.

  Normally, as shown in FIG. 9, the drive voltage waveform (traveling wave) for rotating the vibration wave motor 103 is 90 ° out of phase between the driver A25 and the driver B26. On the other hand, in the case of a standing wave, since the vibration wave motor 103 is not rotated, the driver A25 and the driver B26 have the same phase as shown in FIG.

  As described above, when a driving voltage is applied to the piezoelectric element 7 so as to generate a standing wave in the vibrator 2 shown in FIG. 4, the vibrator 2 and the flange 3 are slightly floated, and the vibration wave motor 103 Holding torque drops significantly.

  Note that the predetermined time T after the vibration wave motor 103 is stopped may be changed depending on the driving state before the stop. For example, it may be shorter than usual when the rotational speed of the vibration wave motor 103 is very small during 30 minutes before the stop, and conversely, it may be lengthened when continuously moving.

  Further, the predetermined time T may be changed between the monitoring mode 1 and the monitoring mode 2 described above. Further, the predetermined time T may be changed depending on the ambient temperature and humidity of the vibration wave motor 103.

  Furthermore, after the predetermined time T has elapsed (NO in step S13), the monitoring mode 2 ends. However, after that, only the detection of the encoder pulse by the encoder sensor 106 may be performed. Does not generate standing waves. Further, the vibration wave motor 103 may be driven and controlled so as to return to the position where it was stopped at that time.

  As described above, according to the present embodiment, the vibration wave motor 103 is controlled as shown in FIGS.

  Thus, when the holding torque immediately after the vibration wave motor 103 is continuously used is large, when the user tries to manually rotate the camera unit 102 or the pan unit 115, the camera unit 102 or the pan unit can be operated with a light operation. The unit 115 can be rotated. Therefore, operability is improved and gear skipping and tooth surface chipping can be prevented.

Furthermore, since the holding torque decreases after a lapse of a predetermined time after the vibration wave motor 103 is stopped, the encoder signal detection at the time of stop is stopped and the standing wave is not driven. By controlling in this way, a power saving effect can be obtained as compared with a case where a standing wave is always generated when the vibration wave motor 103 is manually rotated.
[Other embodiments]
In the above embodiment, the vibration wave motor 103 (110) is mounted on the pan / tilt camera 100 and the camera unit 102 is driven by the vibration wave motor 103 (110). However, the present invention is not limited to this. Is not to be done. The present invention can also be applied to a case where the vibration wave motor is mounted on another electronic device and the drive target portion of the electronic device is driven by the vibration wave motor.

  The object of the present invention can also be achieved by executing the following processing. That is, a storage medium storing software program codes for realizing the functions of the above-described embodiments is supplied to a system or apparatus, and a computer (or CPU, MPU, etc.) of the system or apparatus is stored in the storage medium. This is a process of reading the program code.

  In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the program code and the storage medium storing the program code constitute the present invention.

  Moreover, the following can be used as a storage medium for supplying the program code. For example, floppy (registered trademark) disk, hard disk, magneto-optical disk, CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD + RW, magnetic tape, nonvolatile memory card, ROM or the like. Alternatively, the program code may be downloaded via a network.

  Further, the present invention includes a case where the function of the above-described embodiment is realized by executing the program code read by the computer. In addition, an OS (operating system) running on the computer performs part or all of the actual processing based on the instruction of the program code, and the functions of the above-described embodiments are realized by the processing. Cases are also included.

  Furthermore, the present invention includes a case where the functions of the above-described embodiment are realized by the following processing. That is, the program code read from the storage medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. Thereafter, based on the instruction of the program code, the CPU or the like provided in the function expansion board or function expansion unit performs part or all of the actual processing.

It is an upper perspective view of a pan / tilt camera including the vibration wave motor according to the embodiment of the present invention. It is a downward perspective view of a pan-tilt camera provided with a vibration wave motor according to an embodiment of the present invention. It is a block diagram which shows the structure of the drive control system of a vibration wave motor. It is sectional drawing which shows the internal structure of the vibration wave motor in FIG. 1, FIG. 4 is a flowchart showing a procedure of vibration wave motor drive control processing in a monitoring mode 1 which is executed by the vibration wave motor drive control system of FIG. 3. 4 is a flowchart showing a procedure of vibration wave motor drive control processing in a monitoring mode 2 executed by the vibration wave motor drive control system of FIG. 3. FIG. 5 is a diagram illustrating a relationship between a driving frequency supplied to the vibration wave motor of FIG. 4, a rotation speed of the vibration wave motor, and a current value supplied to the vibration wave motor. It is a figure which shows the pulse signal showing the standing wave output from the drive pulse generator in FIG. It is a figure which shows the pulse signal showing the traveling wave output from the drive pulse generator in FIG. It is sectional drawing which shows the structural example of the vibration wave motor which concerns on a prior art example. It is a figure which shows the relationship between the frequency of the drive voltage supplied to a vibration wave motor, and the rotation speed of a vibration wave motor.

Explanation of symbols

2 Vibrator 4 Rotor 7 Piezoelectric Element 20 Control Unit 23 Voltage Control Oscillator 24 Drive Pulse Generator 25 Driver A
26 Driver B
DESCRIPTION OF SYMBOLS 100 Pan tilt camera 102 Camera part 103 Tilt drive vibration wave motor 106 Tilt part encoder sensor 107 Tilt part encoder scale 110 Pan drive vibration wave motor 112 Pan gear 113 Pan part encoder sensor 114 Pan part encoder scale

Claims (7)

An electro-mechanical energy conversion element, a vibration body that vibrates by application of a driving voltage to the electro-mechanical energy conversion element, and a vibration wave motor having a moving body driven by a traveling wave generated by the vibration of the vibration body;
Control means for controlling application of the drive voltage;
A movement detecting means for detecting movement of the drive target portion to which the driving force of the vibration wave motor is transmitted,
When the movement detection unit detects the movement of the drive target unit when the drive voltage is not applied for a predetermined time or less, the control unit applies the drive voltage to the electromechanical energy conversion element. The driving device is configured to apply and generate a standing wave in the vibrating body, and to control the generation of the standing wave when the driving voltage is not applied for a predetermined time.   2. The driving apparatus according to claim 1, wherein the control unit stops the operation of the movement detecting unit when the driving voltage is not applied for a predetermined time.   3. The driving device according to claim 1, wherein the frequency of the standing wave generated in the vibrating body is a frequency in a vicinity of a frequency at which a current value applied to the vibration wave motor is minimum.   In order to generate the standing wave in the vibrating body, the drive voltage applied to the electromechanical energy conversion element is lower than the drive voltage when the vibration wave motor is normally driven. The drive device according to claim 1, wherein:   An electronic apparatus comprising the drive device according to claim 1.   6. The electronic apparatus according to claim 5, wherein the electronic apparatus is an imaging device that rotates in a tilt direction and a pan direction. A vibration wave motor having an electro-mechanical energy conversion element, a vibrating body that vibrates when a driving voltage is applied to the electro-mechanical energy conversion element, and a moving body that is driven by a traveling wave generated by the vibration of the vibrating body; In a method for controlling a drive device comprising:
A detection step of detecting the movement of the drive target part to which the driving force of the vibration wave motor is transmitted;
If movement of the drive target part is detected by the detection step when the drive voltage is not applied for a predetermined time or less, the drive voltage is applied to the electro-mechanical energy conversion element, and the vibration is applied. A control step for generating a standing wave in the body and not generating the standing wave when the driving voltage is not applied for a predetermined time; and
A control method for a driving device comprising:

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