JP5978646B2 - Vibration wave motor, lens barrel, camera, and vibration wave motor control method - Google Patents

Description

  The present invention relates to a vibration wave motor, a lens barrel, a camera, and a method for controlling the vibration wave motor.

In recent years, in lens barrels, the technology for designing and processing optical components has been improved, and high-power zoom can be put into practical use. In such a high magnification zoom lens barrel, a vibration wave motor is often used. However, in the case of a high-magnification zoom lens barrel, the inertia (inertia) of the AF lens is large, and it takes time to start up the AF lens.
On the other hand, in order to shorten the rise time, a method of driving at a driving frequency at which the maximum torque is generated is disclosed (for example, see Patent Document 1).

JP-A-7-227089

  However, the drive frequency at which the maximum torque is generated is in the vicinity of the frequency at which the maximum use speed is generated. Even if it starts with this drive frequency, since the target rotation speed is high, it takes a rise time.

  The present invention solves such problems and provides a vibration wave motor, a lens barrel, a camera, and a vibration wave motor control method that do not require time to start even if the drive body has a large inertia. With the goal.

The present invention is, that solve the problems by following such a solution.

The vibration wave motor of the present invention includes an electromechanical conversion element that generates vibration by a drive signal, a vibration body that contacts the electromechanical conversion element and generates a vibration wave due to the vibration, and a sliding that contacts the vibration body. A vibration wave motor having a surface and a relative motion member driven by the vibration wave, wherein the frequency of the drive signal is gradually lowered from a first frequency band in which the vibration wave motor does not rotate The frequency in the second frequency band in which the rate of increase in the maximum torque of the vibration wave motor that increases with the change is set as the start frequency of the drive signal when the vibration wave motor is started.
Further, the vibration wave motor control method of the present invention includes an electromechanical transducer that generates vibration by a drive signal, a vibrator that contacts the electromechanical transducer and generates a vibration wave by the vibration, and the vibrator And a relative motion member that is driven by the vibration wave, and a first frequency at which the vibration signal does not rotate. When the vibration wave motor is started up, the frequency in the second frequency band in which the rate of increase in the maximum torque of the vibration wave motor that rises as it gradually decreases is the drive signal when the vibration wave motor is started. The starting frequency of

In addition, the said structure may be improved suitably, and at least one part may be substituted for another structure.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is a drive body with a large inertia, the control method of the vibration wave motor, lens barrel, camera, and vibration wave motor which do not require time for starting can be provided.

It is a figure explaining the vibration wave motor of 1st embodiment of this invention. It is a block diagram explaining the vibration wave motor of 1st embodiment, and the control apparatus of a vibration wave motor. It is a figure which shows embodiment which mounted the vibration wave motor of 1st embodiment in the lens-barrel. (A) is a graph showing the relationship between the target rotational speed of the vibration wave motor and the time to reach it, (b) is a graph comparing the rise times when the target rotational speed is high and low, and (c) is the graph. It is the graph which compared the arrival time to the target rotation speed in the case where the maximum torque of a vibration wave motor is large and small. It is a figure explaining the characteristic of a vibration wave motor, (a) is a graph which shows a drive frequency, rotational speed, and maximum torque, (b) is a grab which shows a torque and rotational speed. It is the figure which showed the impedance characteristic of a vibrator | oscillator, (a) is a figure which shows the relationship of fr (n), fs1, and fr (n + 1), (b) is the optimal in the case of the vibration wave motor which has a different outer diameter It is a table | surface which shows various drive frequency and rotational speed. It is a figure explaining the drive method of 1st embodiment. It is a figure explaining the drive method of a comparison form. It is a figure explaining the lens-barrel of 2nd embodiment. It is a figure explaining the lens-barrel of 3rd embodiment.

(First embodiment)
Hereinafter, embodiments of a vibration wave motor 10 according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a diagram illustrating a vibration wave motor 10 according to a first embodiment of the present invention. The vibration wave motor 10 of the present embodiment includes a vibrator 11 and a moving element 20, and the vibrator 11 side is fixed and drives the moving element 20.

  As will be described later, the vibrator 11 includes an electro-mechanical conversion element (hereinafter referred to as a piezoelectric body) 13 such as a piezoelectric element or an electrostrictive element that converts electrical energy into mechanical energy, and a piezoelectric body 13. A progressive vibration wave is generated in the vibrator 11.

The elastic body 14 is made of a metal material having a high resonance sharpness, and has a ring shape. A groove is cut on the opposite surface to which the piezoelectric body 13 is bonded, and the tip surface of the protruding portion (a portion without the groove) becomes the driving surface 16 and is brought into pressure contact with the sliding surface 25 of the moving element 20. The piezoelectric body 13 is joined to the side of the elastic body 14 where the groove is not cut.
The portion where the groove is not cut is referred to as a base portion 18, and the flange 22 extends from the base portion 18 to the inner diameter side, and is fixed by the fixing member 23 at the innermost diameter portion of the flange 22.
As a sliding member, the elastic body 14 is provided with a sliding material 30 such as metal plating or a lubricating coating film on the driving surface 16.

The piezoelectric body 13 is generally made of a material such as lead zirconate titanate, commonly called PZT. In recent years, lead-free materials such as potassium sodium niobate, potassium niobate, and sodium niobate are used because of environmental problems. , Barium titanate, bismuth sodium titanate, potassium bismuth titanate and the like.
Electrodes are arranged on the surface of the piezoelectric body 13 and are divided into two phases (A phase and B phase) along the circumferential direction. In each phase, the electrodes are arranged so that they are alternately polarized every ½ wavelength, and an interval of ¼ wavelength is left between the A phase and the B phase.

  The mover 20 is made of a light metal such as aluminum, and the surface of the sliding surface is alumite-treated (chemical conversion treatment) to improve wear resistance.

The vibration wave motor 10 further includes an output shaft 40 that outputs rotation of the mover 20, a pressurizing member 50 that pressurizes the mover 20 against the vibrator 11, and the like.
The output shaft 40 is coupled to the mover 20 through a rubber 41 member and a stopper member 42 inserted so as to fit into the D cut of the shaft, and the output shaft 40 and the stopper member 42 are fixed by an E clip 43 or the like. The slider 20 is rotated together with the movable body 20.

The rubber 41 between the stopper member 42 and the moving element 20 has a function of being coupled to the moving element 20 and the stopper member 42 due to the adhesiveness of the rubber 41 and does not transmit vibration from the moving element 20 to the output shaft 40. A material having a function of absorbing vibration is preferable.
The pressure member 50 is provided between the gear portion 51 of the output shaft 40 and the bearing 52. With such a structure, the movable element 20 comes into pressure contact with the drive surface 16 of the vibrator 11.

  FIG. 2 is a block diagram illustrating the vibration wave motor 10 and the control device 80 of the vibration wave motor 10 according to the first embodiment. First, driving / control of the vibration wave motor 10 will be described. The vibration wave motor 10 includes an oscillation unit 60, a phase shift unit 62, an amplification unit 64, a rotation detection unit 66, and a control unit 68 that controls them.

The oscillating unit 60 generates a drive signal having a desired frequency according to a command from the control unit 68.
The phase shifter 62 divides the drive signal generated by the oscillator into two drive signals having different desired phases in response to a command from the controller 68.
The amplification unit 64 boosts the two drive signals divided by the phase shift unit 62 to desired voltages, respectively.
The drive signal from the amplifying unit 64 is transmitted to the vibration wave motor 10, and a traveling wave is generated in the vibrator by the application of the drive signal, and the movable element 20 is driven.

The rotation detection unit 66 is configured by an optical encoder, a magnetic encoder, and the like, detects the position and speed of a driven object driven by driving the moving element 20, and transmits the detected value to the control unit 68 as an electric signal. .
The control unit 68 controls the drive of the vibration wave motor 10 and the operation of the vibration wave motor 10 based on a drive command from the CPU 70 in the lens barrel 110 or the camera body. The control unit 68 receives the detection signal from the rotation detection unit 66, obtains position information and speed information based on the values, and the frequency and phase difference of the vibration wave motor 10 oscillator so as to be positioned at the target position. To control.

FIG. 3 shows an embodiment in which the vibration wave motor 10 of the first embodiment is mounted on a lens barrel 110.
The vibration wave motor 10 is attached to a gear unit module 113, and the gear unit module 113 is attached to a fixed cylinder 114 of the lens barrel 110. The rotation of the gear 51 of the vibration wave motor 10 is transmitted to the cam ring 116 via the reduction gear 115 of the gear unit module 113, and the cam ring 116 is driven to rotate. A key groove 117 is cut obliquely with respect to the circumferential direction in the cam ring 116, and the AF ring 119 in which the fixing pin 118 is inserted into the key groove 117 is rotated by the cam ring 116, It is driven in the straight direction in the axial direction and can be stopped at a desired position.
The circuit 121 is provided between the outer fixed cylinder 114a and the inner fixed cylinder 114b of the lens barrel 110, and performs driving and control of the vibration wave motor 10, detection of the rotational speed, detection of the vibration sensor, and the like.

According to the configuration of the present embodiment, the vibration wave motor 10 and the control device 80 of the vibration wave motor 10 operate as follows.
A drive command is issued from the control unit 68, and a drive signal is issued from the oscillation unit 60 of the vibration wave motor 10. The signal is divided into two drive signals having a phase difference of 90 degrees by the phase unit, and is amplified to a desired voltage by the amplification unit 64.

The drive signal is applied to the piezoelectric body 13 of the vibration wave motor 10 to vibrate the piezoelectric body 13. Due to the excitation, fourth-order bending vibration is generated in the elastic body 14.
The piezoelectric body 13 is divided into an A phase and a B phase, and drive signals are applied to the A phase and the B phase, respectively.
The positional phase of the quaternary bending vibration generated from the A phase and the quaternary bending vibration generated from the B phase are shifted by ¼ wavelength.
In addition, since the phase A drive signal and the phase B drive signal are 90 degrees out of phase, the two bending vibrations are combined into four traveling waves.

Elliptic motion occurs at the front of the traveling wave. Therefore, the movable element 20 that is in pressure contact with the drive surface 16 is frictionally driven by this elliptical motion. An optical encoder is arranged in the driving body driven by driving the moving element 20, and an electric pulse is generated therefrom and transmitted to the control unit 68.
The control unit 68 can obtain the current position and current speed based on this signal.
The cam ring 116 is disposed between the fixed cylinder 114 and the AF ring 119, receives the rotational drive of the vibration wave motor 10, and slides while rotating with respect to the fixed cylinder 114 and the AF ring 119.

Here, especially when the lens barrel 110 is a high magnification zoom lens barrel, the weight of the AF lens group becomes heavy. In this case, the inertia (inertia) increases accordingly, and the time required for the start of rotation increases.
FIG. 4 is a diagram for explaining the rise time with respect to the inertia and the target rotation speed of the AF driving unit.
FIG. 4A is a graph showing the relationship between the target rotation speed (target speed) of the vibration wave motor 10 and the time to reach it. As shown in the figure, when the rise time is compared between the case where the target rotational speed is the same and the inertia of the AF drive unit is large and the case where the inertia is small, the rise time is greatly increased when the inertia of the AF drive unit is large. It has increased.
When the weight of the AF lens group increases and the inertia increases accordingly, the rise time becomes longer, a time lag occurs between the control command and the actual operation, and a control time or a scan time is required. Become.

FIG. 4B is a graph comparing rise times when the target rotational speed is high (high) and low (low) when the inertia of the AF driving unit is the same.
As shown in the figure, when the inertia of the AF drive unit is the same, when the target rotational speed is low (low), the time to reach the target rotational speed (rise time) is short, but when the target rotational speed is high (high), the rise time Shows that it takes.

FIG. 4C is a graph comparing the arrival times up to the target rotational speed when the maximum torque of the vibration wave motor 10 is large and when the inertia is the same.
As shown in the figure, it can be seen that the vibration wave motor 10 having a large maximum torque has a significantly shorter rise time than the vibration wave motor 10 having a small maximum torque.

上式において、時定数であるＴｍａｘ・ｔ／Ｉ×ω０が大きいほうが、立ち上がり時間が短くなる。すなわち、立ち上がり時間を短くするためには、
（１）最大トルクを大きくし
（２）目標速度（無負加時の角速度ω０）を低めにすること、
が効果的である。 The following equation expresses the behavior of these rise times by an approximate expression.

In the above equation, the rise time becomes shorter as the time constant Tmax · t / I × ω0 is larger. In other words, to shorten the rise time,
(1) Increasing the maximum torque (2) Decreasing the target speed (angular speed ω0 with no negative load),
Is effective.

The present invention takes advantage of this.
FIG. 5 is a diagram for explaining the characteristics of the vibration wave motor 10.
As shown in FIG. 5A, when driving an AF lens or the like, when the power is turned on, the drive frequency of the drive signal starts from the frequency fs0 in the first frequency band in which the vibration wave motor does not rotate, and gradually. To lower. The rotation starts at the drive frequency f0, and the drive band is up to the flow of the maximum use rotation number. fr is the resonance frequency, but the resonance point is not used up to this frequency because its behavior is unstable.

On the other hand, looking at the characteristics of the maximum torque with respect to the drive frequency, it increases almost linearly on the low frequency side from the time of f0 (line a), and is close to the maximum torque at fs1 (point p). Then, the characteristic becomes slightly larger toward the flow (line b).
FIG. 5B is a diagram showing the torque-rotation speed at the drive frequencies flow, fs2, fs1, and f1, but the vibration wave motor 10 is based on the principle of frictionally driving the drive force of the resonating vibrator 11. Even if the amplitude of the vibrator 11 approaches resonance and increases, the maximum torque does not increase, but the maximum torque reaches a peak at a certain amplitude (driving frequency).

  With such a vibration wave motor 10, from the viewpoint of the optimum frequency at which the rise time is most shortened, in consideration of the previous study of FIG. 4, a value close to the maximum torque is obtained, and the rotational speed is so large. There is no fs1.

  FIG. 6 is a diagram showing impedance characteristics of the vibrator 11 of the vibration wave motor 10 of the present embodiment. FIG. 6A is a diagram showing the relationship between fr (n), fs1 and fr (n + 1) fs1, and FIG. 6B is a diagram of a vibration wave motor having a case of outer diameter (1) 12 mm and (2) 62 (mm). It is a table | surface which shows the optimal drive frequency fs1 and rotation speed Rev0 in the case.

When the order of the vibration mode of the traveling wave vibration (bending vibration) used for driving is n order (n = 4 in the first embodiment), the resonance frequency is fr (n), and the upper order ( When the resonance frequency of (n + 1) is fr (n + 1), the position of fs1 where the rise time is the shortest is a value between fr (n) and fr (n + 1), and the difference from fr (n) is , Fr (n + 1) and fr (n + 1) are about 25% to 40%, preferably 34% to 36%, more preferably about 35% of the difference.
That is, the following formula is satisfied.
{Fs1-fr (n)} / {fr (n + 1) -fr (n)} ≈0.25-0.40
Preferably,
({Fs1-fr (n)} / {fr (n + 1) -fr (n)} ≈0.34-0.36)
More preferably,
({Fs1-fr (n)} / {fr (n + 1) -fr (n)} ≈0.35)

The rotational speed Rev0 at the drive frequency fs1 is about ½ or less, preferably about 7 to 35%, more preferably about the maximum operating rotational speed (upper rotational speed for stable driving) Rev1. 11-15%.
That is, the following formula is satisfied.
Rev0 / Rev1 <0.5
Preferably,
(Rev0 / Rev1≈0.7 to 0.35)
More preferably,
(Rev0 / Rev1≈0.11 to 0.15)

Furthermore, the drive frequency flow at the maximum use rotation speed (the upper limit rotation speed for stable driving) is substantially within the following range.
0.02 ≦ {flow−fr (n)} / (fr (n + 1) −fr (n)) ≦ 0.0

Next, the driving method of the first embodiment will be described with reference to FIG.
In a state where there is no drive command from the control unit 68 (t0),
Drive frequency: fs0
Drive voltage: Voltage V0 (= 0V)
Phase difference between A phase and B phase: 0 degree.

When a drive command comes from the control unit 68 (t1)
Drive frequency: fs1
Drive voltage: Voltage V1
Phase difference between phase A and phase B: 90 degrees (-90 degrees during reverse drive)
And is driven at the rotational speed Rev0.

The drive frequency is gradually lowered, the frequency becomes flow at t3, and the rotation speed becomes Rev1 and the maximum rotation speed.
At t1, since the drive frequency is set to fs1 with the best rise time, the time lag with the control command is minimized, so that the time to reach the maximum rotation speed and the target rotation speed is shortened, and the control time and scan time are reduced. Shortened.

  In FIG. 7, the frequency is set to fs1 at the start of driving (t1), and the frequency is gradually lowered to flow to the maximum rotation speed (t3). However, the frequency is set to fs1 at the start of driving (t1), and the frequency is set. May be gradually changed to the frequency of the target rotational speed.

FIG. 8 shows a control method of the comparative form.
When a drive command is received from the control unit 68 (t1)
Drive frequency: fs0
Drive voltage: Voltage V1
The phase difference between the A phase and the B phase is set to 90 degrees, and the drive frequency is gradually changed to flow. However, the rotation does not occur until the frequency f0, and the rotation speed is increased even if the drive frequency of the control command becomes flow. It can be seen that a large time lag occurs without catching up. In this case, controllability is not good due to a large time lag.

There are two methods for setting the value of the driving frequency fs1.
(1) Measure impedance in the vibrator state, detect fr (n), fr (n + 1),
fs1−fr (n) = (fr (n + 1) −fr (n)) × 0.35
And how to.
(2) Rotation is driven by the vibration motor unit, a drive frequency at which a rotation speed of about 13% of the maximum use rotation speed is generated is detected, and the value is set as fs1.

According to the inventor's experiment,
(1) The value of fs1 is practically effective if the range of {fs1-fr (n)} / (fr (n + 1) -fr (n)) is 0.25 to 0.40. I found out that For this reason, when setting with the impedance in the vibrator state, when fs1 = (fr (n + 1) −fr (n)) × α, α may be set to 0.25 to 0.40.
(2) Regarding the setting of fs1 from the maximum usable rotational speed, it has been found that if the range of several Rev0 / Rev1 is in the range of 0.07 to 0.35, an effect can be obtained practically. The drive frequency at which the rotational speed of 7 to 35% of the number is generated may be detected, and the value may be set as fs1.

(Second embodiment)
FIG. 9 is a diagram illustrating the lens barrel 200 according to the second embodiment of the present invention, and is a diagram showing a state in which a ring-shaped vibration wave motor 210 is incorporated in the lens barrel 200.

  The vibrator 211 is an elastic body in which an electro-mechanical conversion element 213 (hereinafter referred to as a piezoelectric body) such as a piezoelectric element or an electrostrictive element that converts electrical energy into mechanical energy and a piezoelectric body 213 are joined. 214. The traveling wave is generated in the vibrator 211. In the present embodiment, the traveling wave is described as 9 traveling waves as an example.

  The elastic body 214 is made of a metal material having a high resonance sharpness, has a circular shape, and has a groove on the opposite surface to which the piezoelectric body 213 is bonded. The tip surface of the portion where there is no groove becomes the driving surface 216 and is brought into pressure contact with the driving surface 225 of the moving element 220. The reason for cutting the groove is to make the neutral surface of the traveling wave as close to the piezoelectric body 213 as possible, thereby amplifying the amplitude of the traveling wave on the drive surface 216.

  The piezoelectric body 213 is divided into two phases (A phase and B phase) along the circumferential direction, and in each phase, elements in which polarization is alternated every 1/2 wavelength are arranged, An interval of 1/4 wavelength is provided between the A phase and the B phase.

A nonwoven fabric 252, a pressure plate 254, and a pressure member 250 are disposed under the piezoelectric body 213.
The nonwoven fabric 252 is an example of felt, and is disposed below the piezoelectric body 213 so that the vibration of the vibrator 211 is not transmitted to the pressure plate 254 and the pressure member 250.
The pressure plate 254 is configured to receive pressure from the pressure member 250.
The pressure member 250 is disposed under the pressure plate 254 and generates pressure.

  In the present embodiment, the pressure member 250 is a disc spring, but it may be a coil spring or a wave spring instead of a disc spring. The pressure member 250 is held by being fixed to the fixing member 223 by the pressing ring 251.

The mover 220 is made of a light metal such as aluminum, and a sliding material for improving wear resistance is provided on the surface of the sliding surface 225.
A vibration absorbing member such as rubber 243 is disposed on the side opposite to the vibrator 211 in the moving element 220 in order to absorb vibration in the vertical direction of the moving element 220, and an output transmission member 242 is further disposed.

The output transmission member 242 regulates the pressurization direction and the radial direction by a bearing 253 provided on the fixed member 223, thereby regulating the pressurization direction and the radial direction of the moving element 220. .
The output transmission member 242 has a protrusion 241 from which the fork 230 connected to the cam ring 260 is engaged, and the cam ring 260 is rotated as the output transmission member 242 rotates.

A key groove 261 is obliquely cut in the cam ring 260, and a fixing pin 263 provided on the AF ring 262 is engaged with the key groove 261 so that the cam ring 260 is driven to rotate. As a result, the AF ring 262 is driven in the straight direction in the optical axis direction, and can be stopped at a desired position.
In the fixing member 223, a pressing ring 251 is attached with a screw, and by attaching this, a part from the output transmission unit to the moving element 220, the vibrator 211, and the spring can be configured as one motor unit.

Also in the second embodiment, if the method of setting the drive frequency fs1, setting the drive frequency fs1 at the same time as the start of driving, driving to the target speed, and controlling to the target speed, the time lag with the control command is minimized, so the maximum rotation The time to reach the target speed such as the number is shortened, and the control time is shortened.
The setting of the value of the driving frequency fs1 is the same as in the first embodiment.
(1) When setting the impedance in the vibrator state,
When fs1−fr (n) = (fr (n + 1) −fr (n)) × α, α is 0.25 to 0.40, preferably 0.34 to 0.36, and more preferably 0.35. Set with.
(2) About fs1 setting from the maximum use rotation speed, it is about 1/2 or less of the maximum use rotation speed, preferably about 7 to 35%, more preferably 11 to 15%. The frequency is detected and its value is set to fs1.

(Third embodiment)
FIG. 10 is a diagram illustrating the lens barrel 300 according to the third embodiment of the present invention, and is a diagram showing a state in which the vibration wave motor 310 is incorporated in the lens barrel 300.

In the present embodiment, the vibration wave motor 310 is a linear type.
The vibrator 311 is pressed against the moving element 320 by a pressure spring 334 provided on the support member 333, and the pressure spring 334 fits into the groove 335 at the center of the vibrator 311, thereby causing the vibrator 311 to move in the longitudinal direction. It is supported. The direction of pressure applied to the vibrator 311 is made to coincide with the circumferential tangential direction of the lens barrel 300, and the arrangement of the pressure spring 334 prevents the lens barrel 300 from being enlarged in the radial direction. .

  The configuration of the vibrator 311 includes a piezoelectric body 313 and a sliding member 312 installed at an end. The vibrator 311 body has a standing wave of longitudinal primary mode vibration and a constant of bending secondary mode vibration. A standing wave is generated, and elliptical motion is generated at points C and D where the sliding member 312 is attached. When the sliding surface 325 of the moving element 320 is brought into pressure contact with the driving surface 316 of the sliding member 312, the moving element 320 receives a frictional force due to elliptical motion and is driven. The support member 333 is attached to the fixed cylinder 314.

  The mover 320 is made of a light metal such as aluminum, and the surface of the sliding surface 325 is provided with sliding plating for improving wear resistance. The moving element 320 is fixed to the linear guide 340, the linear guide 340 is fixed to the fixed cylinder 314, and the moving element 320 is movable in a linear direction with respect to the fixed cylinder 314.

The moving element 320 is provided with a projection 337, from which a fork 330 connected to the AF ring 362 is engaged, and the AF ring 362 is driven straight.
The AF ring 362 has a structure that is movable along a first straight rail 341 and a second straight rail 342 provided on the fixed cylinder 314. Guide portions 343 and 344 provided on the AF ring 362 are engaged with the straight rails 341 and 342, and when the moving element 320 is driven in a straight line, it is driven in the straight direction in the optical axis direction and stopped at a desired position. It is made possible.

Also in the third embodiment, if the method of setting the drive frequency fs1, setting the drive frequency fs1 at the same time as the start of driving, driving to the target speed, and controlling to the target speed, the time lag with the control command is minimized, so the maximum rotation The time to reach the target speed such as the number is shortened, and the control time is shortened.
The setting of the value of the driving frequency fs1 is the same as in the first and second embodiments.
(1) The value of fs1 is practically effective if the range of {fs1-fr (n)} / (fr (n + 1) -fr (n)) is 0.25 to 0.40. I found out that For this reason, when setting with the impedance in the vibrator state, when fs1 = (fr (n + 1) −fr (n)) × α, α may be set to 0.25 to 0.40.
(2) Regarding the setting of fs1 from the maximum usable rotational speed, it has been found that if the range of several Rev0 / Rev1 is in the range of 0.07 to 0.35, an effect can be obtained practically. The drive frequency at which the rotational speed of 7 to 35% of the number is generated may be detected, and the value may be set as fs1.

(Deformation)
The present invention is not limited to the above-described embodiment, and various modifications and changes as described below are possible, and these are also within the scope of the present invention.
For example, in this embodiment, a vibration wave motor using a progressive vibration wave is used. In the first embodiment, a progressive vibration wave motor 210 having a wave number of 4 is used. In the second embodiment, a progressive vibration wave motor 210 having a wave number of 9 is used. Although disclosed, similar effects can be obtained with the same configuration and method at other wave numbers such as 5, 6, 7, 8, 10 or more.

  10, 210, 310: Vibration wave motor, 13, 213, 313: Piezoelectric body, 14, 214: Elastic body, 16, 216, 316: Driving surface, 20, 220, 320: Mover, 25, 225, 325: Sliding surface

Claims (10)

An electromechanical transducer in which vibration is generated by a drive signal;
A vibrating body in contact with the electromechanical transducer and generating a vibration wave by the vibration;
In a vibration wave motor having a sliding surface that contacts the vibrating body, and a relative motion member driven by the vibration wave,
When the frequency of the drive signal is gradually lowered from the first frequency band in which the vibration wave motor does not rotate, the increase rate of the maximum torque of the vibration wave motor that rises accordingly is changed. A vibration wave motor characterized in that a frequency in a frequency band is set as a start frequency of the drive signal when the vibration wave motor is started. The vibration wave motor according to claim 1,
The vibration frequency motor is characterized in that the start frequency is a frequency at which a rotation speed equal to or less than half of a maximum use rotation speed of the vibration wave motor is obtained. In the vibration wave motor according to claim 1 or 2,
The order of the vibration mode for driving the vibration wave motor is n-th order, the resonance frequency of the vibration mode is fr (n), and the resonance frequency of the n + 1-order vibration mode one above the n-th vibration mode is fr ( n + 1),
The second frequency band is
fr (n) + α × (fr (n + 1) −fr (n)) 0.25 ≦ α ≦ 0.40
A vibration wave motor having a frequency band of In the vibration wave motor according to any one of claims 1 to 3,
When the maximum operating rotational speed of the vibration wave motor is Rev1, and the maximum rotational speed achieved at the starting frequency is Rev0,
0.07 ≦ Rev0 / Rev1 ≦ 0.35
This is a vibration wave motor.   A lens barrel comprising the vibration wave motor according to claim 1.   A camera comprising the vibration wave motor according to claim 1. An electromechanical transducer in which vibration is generated by a drive signal;
A vibrating body in contact with the electromechanical transducer and generating a vibration wave by the vibration;
In a control method of a vibration wave motor having a sliding surface that contacts the vibration body and a relative motion member driven by the vibration wave,
When the frequency of the drive signal is gradually lowered from the first frequency band in which the vibration wave motor does not rotate, the increase rate of the maximum torque of the vibration wave motor that rises accordingly is changed. A method for controlling a vibration wave motor, wherein a frequency in a frequency band is set as a start frequency of the drive signal when the vibration wave motor is started. In the control method of the vibration wave motor according to claim 7,
The method for controlling a vibration wave motor, wherein the start frequency is a frequency at which a rotation speed equal to or less than half of a maximum use rotation speed of the vibration wave motor is obtained. In the control method of the vibration wave motor according to claim 7 or 8,
The order of the vibration mode for driving the vibration wave motor is n-th order, the resonance frequency of the vibration mode is fr (n), and the resonance frequency of the n + 1-order vibration mode one above the n-th vibration mode is fr ( n + 1),
The second frequency band is
fr (n) + α × (fr (n + 1) −fr (n)) 0.25 ≦ α ≦ 0.40
A control method for a vibration wave motor, characterized in that the frequency band is as follows. In the control method of the vibration wave motor according to any one of claims 8 to 9,
When the maximum operating rotational speed of the vibration wave motor is Rev1, and the maximum rotational speed achieved at the starting frequency is Rev0,
0.07 ≦ Rev0 / Rev1 ≦ 0.35
The control method of the vibration wave motor characterized by the above-mentioned.

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