JP2012242743A - Lens barrel and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens barrel that improves stillness in wobbling operation, and an electronic camera.SOLUTION: A lens barrel includes: a vibration actuator for driving a focusing lens that allows a subject image to be focused; an amplifier part for applying a pair of amplified drive signals to the vibration actuator; a phase shift part for changing a phase difference between the pair of the drive signals; and a control part for executing a first process to allow the phase shift part to perform an operation for periodically changing the phase difference between the pair of drive signals upon the input of a signal for instructing the vibration actuator to drive.

Description

  The present invention mainly relates to a lens barrel and an imaging device.

  A vibration wave motor (vibration actuator) generates a progressive vibration wave (hereinafter referred to as a vibration wave) on a driving surface of an elastic body by utilizing expansion and contraction of a piezoelectric body, as known in Japanese Patent Publication No. 01-015354. Let The generated traveling wave causes an elliptical motion on the drive surface, and the moving element that is in pressure contact with the wavefront of the elliptical motion is driven. Such a vibration wave motor has a feature that it has a high torque even at a low rotation, and when mounted on a drive device, the gear of the drive device can be omitted, so that the gear noise is reduced and silence is achieved. There is an advantage that the positioning accuracy can be improved.

On the other hand, the vibration wave motor has been used as an interchangeable lens for a still camera. However, the use of the vibration wave motor for an interchangeable lens for an electronic camera has shifted with the recent progress and spread of the electronic camera.
In the electronic camera, in addition to still image shooting, there is a demand from the market that video recording and voice recording can be performed together with video recording. Taking an image of a moving image in an electronic camera having an interchangeable lens equipped with a vibration wave motor is disclosed in Japanese Patent Application Laid-Open No. 2004-228620, and describes an advantage for quietness.

Japanese Patent Laid-Open No. 08-080073

  However, the process of developing an electronic camera capable of shooting a movie by the inventor cannot satisfy the silence required when shooting a movie with an electronic camera simply by using an interchangeable lens equipped with a vibration wave motor. It became clear in. Specifically, in the auto focus (AF) operation in moving image shooting, the wobbling operation for detecting the proper in-focus position of the subject by moving the focusing lens back and forth with respect to the optical axis direction. During this period, noise generated from the vibration wave motor was detected by the microphone, and the silence was impaired.

Here, the wobbling operation is performed by driving the vibration wave motor by repeating the following operations. The vibration wave motor driving device applies a pair of drive signals having a predetermined voltage and phase difference to the vibration wave motor, rotates the focusing lens in the forward direction, and then moves the focusing lens forward. Stop the application and stop the vibration wave motor. Subsequently, a pair of drive signals having a predetermined voltage and phase difference are applied to the vibration wave motor, reversed to move the focusing lens backward, and then the application of the pair of drive signals is stopped to vibrate. Stop the wave motor.
In the above-described operation, there is a problem that a minute sound is generated when a pair of drive signals are applied to the vibration wave motor.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a lens barrel and an electronic camera that have improved quietness in a wobbling operation.

(1) In order to solve the above problem, the present invention includes a vibration actuator that drives a focusing lens that focuses an image of a subject, an amplification unit that applies a pair of drive signals amplified to the vibration actuator, When a phase shift unit that changes the phase difference between the pair of drive signals and a signal that instructs driving of the vibration actuator are input, an operation that periodically changes the phase difference between the pair of drive signals is performed as the phase shift unit. And a control unit that executes a first process to be performed by the unit.
(2) Further, in the present invention described above, the range of the phase difference between the pair of drive signals is determined according to the moving speed of the subject.
(3) Further, according to the present invention, in the above-described invention, the frequency of the pair of drive signals is determined according to a moving speed of the subject.
(4) Further, according to the present invention, in the above-described invention, when a signal instructing driving of the vibration actuator is input to the control unit, the pair of the pair is performed before executing the first process. A second process in which the amplitude of the drive signal is changed to a predetermined first amplitude and applied to the vibration actuator, and after the second process, the amplitude of the pair of drive signals is determined to be greater than the first amplitude. A third process for causing the amplifying unit to perform an operation to be applied to the vibration actuator while increasing the second amplitude, and the time required for the second process is longer than the time required for the first process. Features.
(5) Further, in the present invention according to the present invention, when the vibration actuator is stopped, the control unit decreases the amplitude of the pair of drive signals from the second amplitude to the first amplitude. The amplifying unit is caused to perform an operation to stop application of the pair of drive signals later.
(6) In the invention described in the above, the present invention further includes a detection unit that detects a position of the focusing lens, and the control unit is configured to detect a position of the focusing lens detected by the detection unit. It is determined whether or not it is positioned in the vicinity of the focusing position, and when the focusing lens is positioned in the vicinity of the focusing position, an operation of periodically changing the phase difference between the pair of drive signals is performed by the phase shift unit. It is made to carry out.
(7) Further, in the invention described in the above, the present invention is characterized in that the focusing lens moves in the optical axis direction of the focusing lens without rotating.
(8) In the present invention, a vibration actuator that drives a focusing lens that focuses an image of a subject, an amplification unit that applies a pair of drive signals amplified to the vibration actuator, and a pair of drive signals When a phase shift unit for changing the phase difference and a signal for instructing driving of the vibration actuator are input, the phase shift unit performs an operation of periodically changing the phase difference between the pair of drive signals. An image pickup apparatus comprising: a control unit that executes processing.

  According to the present invention, in the wobbling operation, noise generated from the vibration wave actuator can be suppressed and quietness can be improved.

It is a schematic block diagram which shows the structure of the electronic camera 1 in 1st Embodiment. It is the schematic which shows the structure of the lens-barrel 10 in the embodiment. It is the schematic which shows the structure of the vibration wave motor 12 in the embodiment. It is a schematic block diagram which shows the structure of the vibration wave motor drive device 14 in the embodiment. FIG. 4 is a diagram showing a relationship between a phase difference of drive signals applied to the vibration wave motor 12 and a rotation speed of the vibration wave motor 12. An example of the relationship between the drive frequency, amplitude (drive voltage), and phase difference of the drive signals Sa and Sb, the rotation speed of the vibration wave motor 12, and the AF lens position when the subject is stationary in the embodiment. It is the figure shown in time series. An example of the relationship between the frequency, voltage (amplitude) and phase difference of the drive signals Sa and Sb, the rotational speed of the vibration wave motor 12, and the AF lens position when the subject is moving at a constant speed in the embodiment. It is the figure which showed these in time series. The frequency, voltage (amplitude), and phase difference of the drive signals Sa and Sb when the stopped subject starts moving at a constant acceleration in the embodiment, the rotational speed of the vibration wave motor 12, and the AF lens position. It is the figure which showed an example of the relationship in time series. The frequency, voltage (amplitude), and phase difference of the drive signals Sa and Sb when the stopped subject starts moving at a constant acceleration in the embodiment, the rotational speed of the vibration wave motor 12, and the AF lens position. It is the figure which showed an example of the relationship in time series. It is the schematic which shows the structure of 10 A of lens barrels in 2nd Embodiment. It is the schematic which shows the structure of the lens-barrel 10B of 3rd Embodiment. It is a figure which shows the structure of the vibration wave motor 12B in the embodiment. It is a figure which shows operation | movement of the vibration wave motor 12B in the same embodiment.

<Outline of the present invention>
When the inventor of the present invention applies a pair of drive signals to a vibration wave motor (vibration wave actuator) when moving the focusing lens back and forth in a wobbling operation at the time of moving image shooting, minute noise is generated in the moving image. I found the problem of being captured by a microphone that detects sound when shooting. The cause is that when the amplitude of a pair of drive signals applied to the vibration wave motor is changed stepwise from 0 [V] to a predetermined voltage, noise of various frequencies is generated from the stator of the vibration wave motor. Clarified that audible sound is recorded. The noise depends on the amplitude voltage to be changed stepwise, and when the amplitude voltage is small, it has been found that the noise pressure of the noise tends to decrease according to the amplitude.
Therefore, the noise generated when a pair of drive signals is applied to the vibration wave motor is changed stepwise to an amplitude smaller than the sound pressure detected by the microphone, and then the amplitude of the pair of drive signals is set to a predetermined voltage. For example, noise is prevented from being detected by driving the vibration wave motor after gradually changing the voltage to the rated voltage.

  Hereinafter, a vibration actuator, a lens barrel, and a camera according to embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1 is a schematic block diagram showing the configuration of the electronic camera 1 in the first embodiment. As shown in the figure, the electronic camera 1 includes a lens barrel 10, an image sensor 20, an AFE (Analog Front End) circuit 30, an image processing unit 40, a buffer memory 50, a recording processing unit 60, and a built-in microphone. 70, a recording IF (Interface) unit 80, a memory 90, a host control unit 100, an operation member 110, and a display unit 120. The electronic camera 1 can be connected to a PC (Personal Computer) 220 that is an external device, and can also be connected to an external microphone 210. The external microphone 210 can be used in place of the built-in microphone 70 when recording.

  As will be described later, the lens barrel 10 has a plurality of optical lenses as an imaging optical system, and forms a subject image on the light receiving surface of the imaging device. In FIG. 1, a plurality of optical lenses are simplified and one lens is illustrated. The lens barrel 10 includes an optical lens group including a third lens group (AF lens) L3, a vibration wave motor 12 as a vibration actuator, and a vibration wave motor drive device 14 as a vibration actuator drive device. Yes.

The imaging element 20 is configured by a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) in which the light receiving elements are two-dimensionally arranged on the light receiving surface. Further, the image sensor 20 photoelectrically converts a subject image via the imaging optical system of the lens barrel 10 by a light receiving element to generate an analog image signal, and outputs the analog image signal to the AFE circuit 30.
The AFE circuit 30 performs gain adjustment (signal amplification in accordance with ISO (International Organization for Standardization) sensitivity) for the analog image signal output from the image sensor 20. The AFE circuit 30 amplifies the analog image signal within a predetermined range in accordance with the ISO sensitivity setting information input from the host controller 100, and incorporates an A / D (Analog Digital) conversion. The circuit converts the amplified analog image signal into digital image data and outputs the digital image data to the image processing unit 40.

The image processing unit 40 performs various types of image processing such as noise processing on the digital image data output from the AFE circuit 30. The buffer memory 50 temporarily stores the digital image data in the pre-process and post-process of image processing on the digital image data by the image processing unit 40.
The recording processing unit 60 amplifies the audio signal detected by the built-in microphone 70 built in the electronic camera 1 or the external microphone 210 provided outside the electronic camera 1, and controls the amplified signal as digital audio data. Output to the unit 100. In addition, the recording processing unit 60 detects that the external microphone 210 is connected, and outputs a signal indicating that the external microphone 210 is connected to the upper control unit 100.

The storage IF unit 80 is connected to a recording medium such as a memory card 81 and writes and reads data to and from the connected memory card 81. The memory 90 stores captured digital image data.
The operation member 110 includes a mode dial, a cross key, a determination button, a release button, and the like, and outputs an operation signal corresponding to each operation to the upper control unit 100. Still image shooting and moving image shooting are switched by the operation of the operation member 110 by the user.
The display unit 120 is configured by a liquid crystal panel or the like, and displays data such as images and operation menus input from the host control unit 100.

  The host control unit 100 is configured by a microprocessor or the like, and is executed by the electronic camera 1 by executing a program stored in a ROM (Read Only Memory) (not shown) or an EEPROM (Electrically Erasable Programmable Read Only Memory). Centralized control of processing. The host control unit 100 performs, for example, AF operation control, AE (automatic exposure) operation control, automatic white balance control, and the like. In the AF operation control, the host control unit 100 outputs a drive command signal that causes the vibration wave motor driving device 14 of the lens barrel 10 to drive the vibration wave motor 12 and imaging information.

The host control unit 100 is connected to an external PC 220. The PC 220 is connected to the host controller 100 to read out digital image data and digital audio data stored in the memory 70 via the host controller 100.
Here, the drive command signal is a signal that instructs the start of driving of the vibration wave motor 12. The shooting information includes information indicating the target position of the AF lens L3 that forms an image of the subject to be imaged on the image sensor, and the moving direction, moving speed, and acceleration of the subject. The host control unit 100 generates shooting information by detecting the moving direction, moving speed, and acceleration of a subject using a known subject tracking function described in, for example, Japanese Patent Application Laid-Open No. 2001-243478. The moving direction of the subject is a direction in the optical axis direction of the imaging optical system.

  FIG. 2 is a schematic view showing a configuration of the lens barrel 10 in the same embodiment. The lens barrel 10 includes an outer fixed cylinder 101 that covers the outer periphery of the lens barrel 10, a first inner fixed cylinder 102 that is positioned closer to the subject on the inner peripheral side than the outer fixed cylinder 101, and the outer fixed cylinder 101. A second inner fixed cylinder 103 positioned on the image side on the inner peripheral side, and between the outer fixed cylinder 101 and the first inner fixed cylinder 102, a vibration wave motor 12, a vibration wave motor driving device 14, A gear unit module 104 that reduces and transmits the rotational speed of the vibration wave motor 12 is disposed and fixed to the first inner fixed cylinder 102. The gear unit module 104 has a reduction gear 105 that reduces and transmits the output of the vibration wave motor 12.

  Further, the first lens group L1 and the second lens group L2 are fixed to the first inner fixed cylinder 102 from the subject side, and the fourth lens group L4 is fixed to the second inner fixed cylinder 103. Between the second lens group L2 and the fourth lens group L4, a third lens group L3 which is an AF lens for focusing held by the AF ring 107 is disposed. That is, the first lens group L1, the second lens group L2, the third lens group L3, and the fourth lens group L4 are sequentially arranged from the subject side to the image sensor side in the optical axis direction.

A cam ring 106 is provided between the AF ring 107 and the first inner fixed cylinder 102 so as to be rotatable about the optical axis direction as a center axis. The cam ring 106 is transmitted to the vibration wave motor 12 transmitted by the reduction gear 105. It rotates by the output of. A key groove 106a is cut in a spiral shape in the circumferential direction inside the cam ring 106. A fixing pin 107 a is provided on the outer peripheral side of the AF ring 107, and the fixing pin 107 a is inserted into the key groove 106 a of the cam ring 106.
In addition, a vibration wave motor drive device 14 is disposed on the holding portion 101 a that protrudes inward from the inner peripheral side of the outer fixed cylinder 101, and the vibration wave motor drive device 14 is electrically connected to the vibration wave motor 12 to vibrate. The wave motor 12 is driven.

  Due to the configuration of the lens barrel 10 described above, the output of the vibration wave motor 12 is rotated by rotating the cam ring 106 via the reduction gear 105, whereby the fixed pin 107 a is guided and moved to the key groove 106 a, and the AF ring 107. The AF ring 107 can be stopped by moving the cam ring 106 in the optical axis direction. That is, by driving the vibration wave motor 12, the AF ring 107 is driven in the optical axis direction and the third lens group L3 is moved, so that a focused subject image can be formed on the image sensor. .

  FIG. 3 is a schematic diagram showing the configuration of the vibration wave motor 12 in the same embodiment. The vibration wave motor 12 includes a vibrator 121, a moving element 124, a fixed member 125, a bearing 126, an output shaft 127, a pressure member 128, a bearing receiving member 129, a stopper 130, a rubber member 131, and a gear member. 132 and a pressure adjusting washer 133 are provided.

  The vibrator 111 includes an electro-mechanical conversion element (hereinafter, referred to as a piezoelectric body 123) such as a piezoelectric element or an electrostrictive element that converts electrical energy into mechanical energy, and an elastic body 122 connected to the piezoelectric body 123. When a voltage is applied to the vibrator 121, for example, four traveling waves are generated. The elastic body 122 is made of a metal material having a high resonance sharpness, and has an annular shape. Further, the elastic body 122 is provided with a comb-shaped portion 122a having a groove formed on the opposite surface to which the piezoelectric body 123 is bonded, and a tip surface of the protruding portion (a portion having no groove) serves as a driving surface. The portion 122a is in pressure contact with the movable element 124. Here, the groove is provided in the elastic body 122 in order to amplify the amplitude of the traveling wave on the driving surface of the elastic body 122 by bringing the neutral surface of the traveling wave as close as possible to the piezoelectric body 123 side. The voltage body 123 is generally composed of a material such as lead zirconate titanate commonly called PZT, but in recent years, it is a lead-free material such as potassium sodium niobate, potassium niobate, sodium niobate, potassium, which is an environmental problem. It may be composed of barium titanate, bismuth sodium titanate, potassium bismuth titanate, and the like.

  In the elastic body 122, a portion where no groove is provided is referred to as a base portion 112b. The base portion 122b is joined to the piezoelectric body 123, and the driving surface of the elastic body 122 is lubricated. The piezoelectric body 123 is divided into two phases (A phase and B phase) along the circumferential direction, and in each phase, the polarization is alternately arranged every ½ wavelength, and the A phase Between the polarization and the B phase polarization, a quarter wavelength interval is provided.

The moving element 124 is made of a light metal such as aluminum, and the surface of the sliding surface that is in pressure contact with the comb-shaped portion 122a is subjected to surface treatment for improving wear resistance. The output shaft 127 is coupled to rotate together with the moving element 124 via the rubber member 131. The rubber member 131 is preferably butyl rubber or the like having a function of coupling the moving element 124 and the output shaft 127 with adhesiveness of rubber and a function of absorbing vibration so as not to transmit vibration from the moving element 124 to the output shaft 127. is there.
The pressure member 128 is disposed between the gear member 132 fixed to the output shaft 127 and the bearing receiving member 129. The bearing receiving member 129 is inserted inside the bearing 126, and the bearing 126 is inserted inside the fixing member 125. The gear member 132 is inserted so as to fit in the D cut of the output shaft 127, is fixed by a stopper 130 such as an E clip, and rotates together with the output shaft 127. A pressure adjusting washer 133 is disposed between the pressure member 128 and the bearing receiving member.

  As described above, the vibration wave motor 12 is configured so that the moving element 124 is in pressure contact with the vibration body drive surface and is moved by the pressure adjusting washer 133 disposed between the pressure member 128 and the bearing receiving member 129. The pressure applied to the child 124 and the comb-shaped portion 122a is an appropriate pressure.

FIG. 4 is a schematic block diagram showing the configuration of the vibration wave motor drive device 14 in the same embodiment. The vibration wave motor drive device 14 includes a control unit 141, an oscillation unit 142, a phase shift unit 143, an amplification unit 144, and a rotation detection unit 147.
In addition, when a drive command signal is input from the host control unit 100 provided in the electronic camera 1, the vibration wave motor drive device 14 sends the vibration wave motor 12 to the vibration wave motor 12 based on the imaging information input from the host control unit 100. A drive frequency which is a frequency of the pair of drive signals Sa and Sb to be applied and a phase difference between the pair of drive signals Sa and Sb are calculated. The vibration wave motor drive device 14 applies a pair of drive signals Sa and Sb having the calculated frequency and phase difference to the vibration wave motor 12 to drive the third lens group L3, which is an AF lens for focusing. The subject is imaged on the image sensor.

The oscillation unit 142 outputs an oscillation signal having a frequency corresponding to the frequency information input from the control unit 141 to the phase shift unit 143.
Based on the phase difference information input from the control unit 141, the phase shift unit 143 generates a signal having the phase difference indicated in the phase difference information with respect to the oscillation signal input from the oscillation unit 142, The signal and the input oscillation signal are output to the amplifying unit 144.

The amplifying unit 144 includes a first amplifying unit 145 and a second amplifying unit 146. The first amplification unit 145 receives the oscillation signal from the phase shift unit 143 and the amplification factor information from the control unit 141. The first amplifying unit 145 amplifies the amplitude of the input oscillation signal according to the input amplification factor information, and the amplified oscillation signal, which is the drive signal Sa, is amplified by the piezoelectric body 123 ( 3).
A signal having a phase difference indicated in the phase difference information with respect to the oscillation signal and the gain information from the control unit 141 are input to the second amplifying unit 146. The second amplifying unit 146 amplifies the input signal having a phase difference according to the input amplification factor information, and the amplified signal, which is the drive signal Sb, is applied to the piezoelectric body 123 of the vibration wave motor 12. Apply.

The first amplifying unit 145 and the second amplifying unit 146 are input from the control unit 141 after applying drive signals Sa and Sb having an amplitude of V ₀ [V] (first amplitude) to the vibration wave motor 12. According to the amplification factor information, the amplitudes of the drive signals Sa and Sb are increased to V ₁ [V] (second amplitude). Here, the amplitude (peak voltage) V ₀ [V] is a voltage value obtained by simulation and measurement by an actual machine, and even if the amplitudes of the drive signals Sa and Sb are changed from 0 to V ₀ [V]. The amplitude (voltage) is such that no noise is detected in the built-in microphone 70. The amplitude (peak voltage) V ₁ [V] is, for example, the rated voltage of the vibration wave motor 12. Further, the pair of drive signals Sa and Sb output from the first amplifying unit 145 and the second amplifying unit 146 have the same frequency as the oscillation signal.
The rotation detection unit 147 includes an optical encoder, a magnetic encoder, and the like, detects the position and moving speed of the vibration wave motor 12, and outputs detection information indicating the detected value to the control unit 141.

  The control unit 141 has a conversion table 141a. The conversion table 141a includes drive signals Sa and Sb applied to the vibration wave motor corresponding to the shooting information input from the host control unit 100 provided in the electronic camera 1 and the detection information input from the rotation detection unit 147. Are stored in advance. The phase difference stored in the conversion table 141a is a value obtained based on an actual measurement result or a simulation. The target position included in the imaging information, the moving direction, moving speed and acceleration of the subject, and the vibration wave motor It is a value corresponding to the combination of the position and rotational speed and the respective parameters. The two phase differences are a maximum value and a minimum value when the phase difference between the drive signals Sa and Sb is periodically changed.

When the drive command signal is input from the host control unit 100, the control unit 141 outputs frequency information indicating a predetermined frequency to the oscillation unit 142, and amplifies the amplification factor information corresponding to the amplitude V ₀ [V]. Output to the unit 144. In addition, when the drive command signal is input from the host control unit 100, the control unit 141 determines the rotation direction of the vibration wave motor 12 from the detection information input from the rotation detection unit 147 and the target position included in the imaging information. The phase difference information indicating either +90 degrees or -90 degrees is output to the phase shifter 143 according to the determined rotation direction. The predetermined frequency is a frequency higher than the frequency range in which the vibration wave motor 12 is driven by the drive signals Sa and Sb.

Thereafter, the control unit 141 changes the amplification factor information output to the amplification unit 144 to increase the amplitudes of the drive signals Sa and Sb from V ₀ [V] to V ₁ [V]. Further, the control unit 141 performs an insertion process for lowering the frequencies of the drive signals Sa and Sb to a frequency range in which the vibration wave motor 12 can be driven, and drives the vibration wave motor 12.
In addition, the control unit 141 controls the wobbling operation when the vibration wave motor 12 starts to move and the AF lens L3 is positioned in the focus appropriate range near the in-focus point. Specifically, two phase differences corresponding to input imaging information and detection information are read from the conversion table 141a, and the phase difference information is changed with the two read phase differences as peaks (maximum value and minimum value). The phase difference between the drive signals Sa and Sb output to the phase shift unit 143 is changed.
Note that whether or not the AF lens L3 is positioned within the proper focus range is determined from the target position included in the imaging information and the position of the vibration wave motor 12 included in the detection information. There is a correlation between the position of the vibration wave motor 12 and the position of the AF lens L3, and the control unit 141 calculates the position of the AL lens L3 from the position of the vibration wave motor 12 by using a predetermined coefficient.

  As described above, the control unit 141 drives the vibration wave motor 12 by controlling the oscillation unit 142, the phase shift unit 143, and the amplification unit 144 based on the imaging information and the detection information. The focus appropriate range is a range including a focal point where the subject forms an image on the image sensor, and is a range determined in advance by measurement, simulation, or the like using an actual device. In addition, when the AF lens L3 is positioned within the proper focus range, a range in which blurring occurring in the subject image formed on the image sensor is not recognized by the user is determined in advance. The control unit 141 drives the vibration wave motor 12 so that the AF lens position falls within the focus appropriate range during moving image shooting.

Hereinafter, a basic operation when the vibration wave motor driving device 14 drives the vibration wave motor 12 will be described.
When a drive command signal is input from the host control unit 100, the control unit 141 outputs frequency information to the oscillation unit 142, outputs phase difference information to the phase shift unit 143, and outputs amplification factor information to the amplification unit 144. To do.

  The oscillation unit 142 generates an oscillation signal having a frequency indicated by the frequency information input from the control unit 141 and outputs the oscillation signal to the phase shift unit 143. When the oscillation signal is input from the oscillation unit 142, the phase shift unit 143 outputs the oscillation signal to the first amplification unit 145, and the phase difference indicated by the phase difference information input from the control unit 141, for example, A signal having a phase difference of 90 degrees is generated, and the generated signal is output to the second amplification unit 146. Each of the first amplification unit 145 and the second amplification unit 146 amplifies the oscillation signal input from the phase shift unit 143 and applies the drive signals Sa and Sb to the vibration wave motor 12. The piezoelectric body 123 is excited when the drive signal Sa is applied to the A-phase electrode and the drive signal Sb is applied to the B-phase electrode, and fourth-order bending vibration is generated in the elastic body 122.

  The piezoelectric body 123 generates quaternary bending vibration generated from the A phase and quaternary bending vibration generated from the B phase when the drive signals Sa and Sb are applied to the A phase and the B phase, respectively. The two bending vibrations are shifted by a quarter wavelength and are combined to generate four traveling waves. When the elliptical motion is generated at the wavefront of the traveling wave, the moving element 124 that is in pressure contact with the driving surface of the elastic body 122 is frictionally rotated, and the rotational motion generated in the vibration wave motor 12 is output to the output shaft 127 and It is transmitted to the gear member 132 (FIG. 3), the reduction gear 105 and the cam ring 106 to move the AF ring 107 in the optical axis direction.

  The rotation detection unit 147 detects the position and moving speed of the vibration wave motor 12 and outputs detection information indicating the detected position and moving speed to the control unit 141. When the AF lens L3 is located within the proper focus range, the control unit 141 detects the detection information input from the position detection unit 147 and the imaging input from the upper control unit 100 for each wobbling period that is a predetermined period. Based on the information, the next phase difference information is calculated, and the vibration wave motor 12 is driven.

FIG. 5 is a diagram showing the relationship between the phase difference of the drive signal applied to the vibration wave motor 12 and the rotational speed of the vibration wave motor 12. The rotational speed of the vibration wave motor 12 is the maximum speed in the forward direction when the phase difference is +90 degrees, and the maximum speed in the reverse direction when the phase difference is -90 degrees. Further, the rotational speed of the vibration wave motor 12 changes according to the phase difference.
The vibration wave motor drive device 14 of the present embodiment performs a wobbling operation in moving image shooting by controlling the rotational speed of the vibration wave motor 12 based on the phase difference between the drive signals Sa and Sb.

Hereinafter, in the case of moving image shooting in the present embodiment, the relationship between the frequency, voltage (amplitude) and phase difference of the drive signals Sa and Sb, the rotational speed of the vibration wave motor 12, and the AF lens position will be described. The following three cases will be described with reference to the figures shown in the series. Here, a case where the vibration wave motor 12 is driven in the forward rotation direction will be described.
1. 1. When the subject is stationary 2. The subject is moving at a constant speed. When a stopped subject starts to move at a constant acceleration

[1. When the subject is stationary]
FIG. 6 shows the drive frequency, amplitude (drive voltage) and phase difference of the drive signals Sa and Sb when the subject is stationary in the same embodiment, the rotational speed of the vibration wave motor 12, and the AF lens position. It is the figure which showed an example of the relationship in time series.

First, when an instruction to start moving image shooting is input through the operation member 110 by a user operation, the upper control unit 110 outputs a drive command signal and shooting information to the vibration wave motor control unit 14. Vibration wave motor control unit 14, when the drive command signal is input, selecting a predetermined drive frequency f0 (maximum frequency) and the driving voltage V _{0 (minimum} voltage), the oscillation frequency information indicating a drive frequency f0 output to section 142, and outputs the amplification factor information indicating an amplification factor corresponding to the driving voltage V ₀ to a driving unit. Further, the vibration wave motor control unit 14 determines the rotation direction of the vibration wave motor 12 from the input detection information and the target position included in the imaging information, and sets a predetermined initial phase difference corresponding to the rotation direction. The phase difference information indicating the value is output to the phase shift unit 143. As the initial value of the phase difference, +90 degrees is selected for the forward direction, and -90 degrees is selected for the reverse direction.

The oscillation unit 142 outputs the input oscillation signal having the drive frequency f0 to the phase shift unit 143. The phase shift unit 143 outputs the input oscillation signal and a signal having a phase difference corresponding to the phase difference information with respect to the input oscillation signal to the amplification unit 144. In the amplification unit 144, the first amplification unit 145 applies the drive signal Sa to the vibration wave motor 12 based on the input oscillation signal and amplification factor information. The second amplifying unit 146 applies the drive signal Sb to the vibration wave motor 12 based on the input signal having the phase difference and the amplification factor information. Thus, the vibration wave motor control unit 14 applies a pair of drive signals Sa and Sb having an amplitude of V ₀ and a drive signal Sb having a phase difference of +90 degrees with respect to the drive signal Sa to the vibration wave motor 12. . At this time, the control unit 141 changes the drive voltages of the drive signals Sa and Sb in a step shape from 0 [V] to V ₀ [V] (time t0).

From time t1 to time t2, the control unit 141 gradually increases the drive voltages of the drive signals Sa and Sb from V ₀ [V] to V ₁ [V].
Next, from time t3 to time t4, the control unit 141 performs an insertion process, and reduces the drive frequencies of the drive signals Sa and Sb to f1. At this time, when the frequencies of the drive signals Sa and Sb reach a driveable frequency range, the vibration wave motor 12 starts driving.
Further, at time t4, when the AF lens position is detected within the focus appropriate range, the control unit 141 reads out two phase differences (+90 degrees and −90 degrees) corresponding to the imaging information and the detection information, and determines the position. The phase difference information is periodically changed and control of the wobbling operation is started.

As shown in the figure, from time t4 to time t5, the phase difference between the drive signals Sa and Sb is +90 degrees, and the vibration wave motor 12 is rotated forward. From time t5 to time t6, the phase difference between the drive signals Sa and Sb is changed from +90 degrees to -90 degrees, and the rotation direction of the vibration wave motor 12 is changed from forward rotation to reverse rotation.
From time t6 to time t7, the phase difference of the drive signal is −90 degrees, and the vibration wave motor 12 is rotating in the reverse direction. From time t7 to time t8, the phase difference between the drive signals Sa and Sb is changed from −90 degrees to +90 degrees, and the rotation direction of the vibration wave motor 12 is changed from forward rotation to reverse rotation.

  From the time t8 to the time t9, the phase difference between the drive signals Sa and Sb is +90 degrees and is rotating forward. Hereinafter, the control unit 141 repeats the operation from the time t4 to the time t8 periodically, for example, at a period of 30 Hz, and controls the vibration wave motor 12 by changing the phase difference information, so that the AF lens position is changed. A wobbling operation that moves back and forth is executed.

[2. When the subject is moving at a constant speed]
FIG. 7 shows the frequency, voltage (amplitude) and phase difference of the drive signals Sa and Sb when the subject is moving at a constant speed in the embodiment, the rotational speed of the vibration wave motor 12, and the AF lens position. It is the figure which showed an example of this relationship in time series.
Since the operation from the time t0 to the time t3 is the same as that when the subject is stationary, the description thereof is omitted.
At time t4, when the AF lens position is detected within the focus appropriate range, the control unit 141 reads out two phase differences (+90 degrees and α degrees) corresponding to the imaging information and the detection information, and obtains the phase difference information. The wobbling operation is started by periodically changing the wobbling operation.

As shown in the figure, from time t4 to time t5, the phase difference between the drive signals Sa and Sb is +90 degrees, and the vibration wave motor 12 is driven in the forward rotation direction at the rotation speed V _S0 . From time t5 to time t6, the phase difference between the drive signals Sa and Sb is changed from +90 degrees to α degrees, and the rotational speed of the vibration wave motor 12 decreases. However, the rotational direction of the vibration wave motor 12 remains normal.
From time t6 to time t7, the phase difference of the drive signal is α degrees, and the vibration wave motor 12 is driven in the forward rotation direction at a rotational speed V _S1 slower than V _S0 . From the time t7 to the time t8, the phase difference between the drive signals Sa and Sb is changed from α degrees to +90 degrees, and the rotational speed of the vibration wave motor 12 increases and becomes V _S0 again. From time t8 to time t9, the phase difference between the drive signals Sa and Sb is +90, and the vibration wave motor 12 is driven in the forward rotation direction at the rotational speed V _S0 .

Thereafter, the control unit 141 periodically repeats the operation from time t4 to time t8, and periodically changes the phase difference information between +90 degrees and α degrees, thereby forming the vibration wave while imaging the subject. The motor 12 is controlled, and the rotational speed of the vibration wave motor 12 is repeatedly changed as V _S0 → V _S1 → V _S0 →.

  The control unit 141 periodically changes the phase difference between the drive signals Sa and Sb based on the two phase differences based on the imaging information and the detection information, similar to the case where the subject is moving at a constant speed. The wobbling operation can be executed by the processing. Since the wobbling operation can be executed without the need to switch the processing based on the imaging information, the processing amount of the control unit 141 does not increase and is suitable for use in an electronic camera.

Even when the rotation direction of the vibration wave motor 12 is the reverse direction, the wobbling operation can be executed by the same processing. At this time, the two phase differences read from the conversion table 141a by the control unit 141 are, for example, −90 degrees and −α degrees. Then, from time t4 to time t5, the phase difference is from -time t4 to time t5, the phase difference between the drive signals Sa and Sb is -90 degrees, and the vibration wave motor 12 is driven in the reverse rotation direction at the rotational speed _VSO. . From time t5 to time t6, the phase difference between the drive signals Sa and Sb is changed from -90 degrees to -α degrees, and the rotational speed of the vibration wave motor 12 decreases. However, the rotation direction of the vibration wave motor 12 remains reversed.

From time t6 to time t7, the phase difference of the drive signal is −α degrees, and the vibration wave motor 12 is driven in the reverse rotation direction at a rotational speed V _S1 slower than V _S0 . From the time t7 to the time t8, the phase difference between the drive signals Sa and Sb is changed from -α degrees to -90 degrees, and the rotational speed of the vibration wave motor 12 is increased to V _S0 again. From time t8 to time t9, the phase difference between the drive signals Sa and Sb is −90, and the vibration wave motor 12 is driven in the reverse direction at the rotational speed V _S0 .
Thereafter, the control unit 141 periodically repeats the operation from time t4 to time t8, and periodically changes the phase difference information between −90 degrees and −α degrees to execute the wobbling operation.

[3. When a stopped subject starts moving at a constant acceleration]
FIG. 8 shows the frequency, voltage (amplitude) and phase difference of the drive signals Sa and Sb, the rotational speed of the vibration wave motor 12, and the AF when the stopped subject starts moving at a constant acceleration in the embodiment. It is the figure which showed an example of the relationship with a lens position in time series.
Since the operation from the time t0 to the time t3 is the same as that when the subject is stationary, the description thereof is omitted.
At time t4, when the AF lens position is detected within the focus proper range, the control unit 141 reads out two phase differences (+90 degrees and −β degrees) corresponding to the imaging information and the detection information, and the phase difference information Is periodically changed to start control of the wobbling operation.

As shown in the figure, from time t4 to time t5, the phase difference between the drive signals Sa and Sb is +90 degrees, and the vibration wave motor 12 is driven in the forward rotation direction at the rotational speed V _S1 . From the time t5 to the time t6, the phase difference between the drive signals Sa and Sb is changed from +90 degrees to -β degrees, and the line speed of the vibration wave motor 12 is decreased to reversely rotate.
From time t6 to time t7, the phase difference between the drive signals Sa and Sb is −β degrees, and the vibration wave motor 12 is driven in the reverse rotation direction at the rotational speed V _S2 . From time t7 to time t8, the phase difference between the drive signals Sa and Sb is changed from −β degrees to +90 degrees, and the rotational speed of the vibration wave motor 12 is increased to rotate it forward.

At time t8, the control unit 141 reads out two phase differences (+90 degrees, −γ degrees) corresponding to the imaging information and the detection information. From time t8 to time t9, the phase difference between the drive signals Sa and Sb is +90 degrees, and the vibration wave motor 12 is driven in the forward rotation direction at the rotation speed V _S1 . From the time t10 to the time t11, the phase difference between the drive signals Sa and Sb is changed from +90 degrees to -γ degrees, and the rotational speed of the vibration wave motor 12 is decreased to rotate in reverse.
Thereafter, the wobbling operation can be executed by repeating the operation from time t4 to time t8.

  When the subject is moving at a constant acceleration, the center value of the moving speed of the subject increases with time, so if the desired rotational speed cannot be obtained with the phase difference between the driving signals Sa and Sb, the driving frequency is also set. By changing together, the vibration wave motor 12 is rotated at a desired rotation speed. FIG. 9 shows the frequency, voltage (amplitude) and phase difference of the drive signals Sa and Sb, the rotational speed of the vibration wave motor 12, and the AF when the stopped subject starts moving at a constant acceleration in the embodiment. It is the figure which showed an example of the relationship with a lens position in time series.

  In this case, not only the phase difference between the drive signals Sa and Sb is changed, but also the frequency of the drive signals Sa and Sb is changed along with the change in the phase difference, so that a desired rotation speed can be obtained. In addition, a wobbling operation can be performed on a subject moving at a constant speed. Further, the drive frequencies of the drive signals Sa and Sb may be stored in advance in the conversion table 141a, similarly to the two phase differences. Thereby, the control part 141 can perform a wobbling operation | movement by the same process in the above-mentioned three cases.

As described above, when driving the vibration wave motor 12 during moving image shooting, the electronic camera 1 according to the present embodiment first sets the amplitudes of the drive signals Sa and Sb applied to the vibration wave motor 12 from 0 [V]. The amplitude is changed stepwise to a predetermined amplitude V ₀ [V]. Thereafter, the electronic camera 1, the driving signal Sa, the amplitude of Sb, the amplitude from the _{0 [V] V 0 [V} ] is gradually increased over time from the processing of changing to _V 0 [V] from A process of changing to V ₁ [V] is executed. Since noise generated when the drive signals Sa and Sb having the amplitude V ₀ [V] are applied to the vibration wave motor 12 is hardly detected by the built-in microphone 70, noise generated when the vibration wave motor 12 is driven is reduced. be able to. Further, when the amplitudes of the drive signals Sa and Sb are changed from V ₀ [V] to V ₁ [V], they are gradually increased over time, so that noise generated from the vibration wave motor 12 can be suppressed. Can be driven quietly.

  The electronic camera 1 of this embodiment is configured to execute the wobbling operation by periodically changing the phase difference between the drive signals Sa and Sb applied to the vibration wave motor 12. As a result, the vibration wave motor is controlled by simple control compared to the conventional method in which the vibration wave motor is temporarily stopped and the phase difference between the pair of drive signals applied is changed to switch between the normal rotation and the reverse rotation of the vibration wave motor. 12 forward rotations and reverse rotations can be switched. Further, noise is generated when the drive signals Sa and Sb are applied to the vibration wave motor 12, but in the electronic camera 1 of the present embodiment, the amplitude (voltage) of the drive signals Sa and Sb when performing the wobbling operation is set. Since the operation that causes noise generation is not performed at a constant value, quiet driving can be performed.

Second Embodiment
FIG. 10 is a schematic diagram showing the configuration of a lens barrel 10A in the second embodiment. The lens barrel 10A includes an outer fixed cylinder 101A that covers the outer periphery of the lens barrel 10A, a first inner fixed cylinder 102A located on the subject side inside the outer fixed cylinder 101A, and an inner side than the outer fixed cylinder 101A. And a second inner fixed cylinder 103A located on the image side.
The lens barrel 10A includes a vibration wave motor 12A that is disposed between the outer fixed cylinder 101A and the second inner fixed cylinder 103A and is fixed to the second inner fixed cylinder 103A by a fixing member 151. .

  Further, the first lens group L1 and the second lens group L2 are fixed to the first inner fixed cylinder 102A from the subject side, and the fourth lens group L4 is fixed to the second inner fixed cylinder 103A. Between the second lens group L2 and the fourth lens group L4, a third lens group L3 which is an AF lens for focusing held by the AF ring 152 is disposed. That is, the first lens group L1, the second lens group L2, the third lens group L3, and the fourth lens group L4 are sequentially arranged from the subject side to the image sensor side in the optical axis direction.

A cam ring 153 is provided between the AF ring 152 and the second inner fixed cylinder 103A so as to be rotatable about the optical axis direction as a center axis. The cam ring 153 is a vibration wave motor transmitted via a fork 154. It rotates by the output of 12A. In addition, a key groove 153a is cut spirally in the circumferential direction inside the cam ring 153. A fixing pin 152 a is provided on the outer peripheral side of the AF ring 152, and the fixing pin 152 a is inserted into the key groove 153 a of the cam ring 153.
In addition, the vibration wave motor drive device 14 is disposed in the holding portion 101a that protrudes inward from the inner peripheral side of the outer fixed cylinder 101A, and the vibration wave motor drive device 14 is electrically connected to the vibration wave motor 12A to vibrate. The wave motor 12 is driven.

  The vibration wave motor 12 </ b> A includes a stator 161 having an elastic body 161 a, a piezoelectric element 161 b that converts electrical energy into mechanical energy, a mover 162 that presses the stator 161 to extract an output, and a stator 161. It consists of a cushioning support member 163 made of a non-woven fabric or the like arranged on the non-driving surface (the surface opposite to the surface in contact with the moving element 162), a pressing plate 164a and a pressing member 164b. It comprises pressure contact means 164 for making pressure contact, and an output transmission member 155 and a press ring 165 for supporting these members from the left and right. The holding ring 165 is fixed to the fixing member 151 with a screw or the like.

The fork 154 is engaged with a protrusion 155 a provided on the output transmission member 155 to transmit the rotational movement of the output transmission member 155 to the cam ring 153. The output transmission member 155 is restricted from moving in the optical axis direction and moving in the radial direction by a bearing 156 attached to the fixed member 151.
A vibration absorbing member 166 such as rubber that absorbs vibration in the optical axis direction of the moving element 162 is disposed on the moving element 162. The vibration absorbing member 166 is in pressure contact with the output transmission member 155 by the pressure contact means 164.

In the present embodiment, an annular vibration wave motor 12A is provided, but the rotational speed and direction can be controlled by the frequency, amplitude, and phase difference of the drive signals Sa and Sb. Since the vibration wave motor control device 14 can perform the same control as the control performed on the vibration wave motor 12 of the first embodiment, the wobbling operation can be performed as in the first embodiment. it can.
Furthermore, since the ring-shaped vibration wave motor 12A is provided, the output of the vibration wave motor 12A can be transmitted to the cam ring 153 without using a gear or the like. Therefore, a smooth wobbling operation can be executed.

<Third Embodiment>
FIG. 11 is a schematic diagram showing the configuration of the lens barrel 10B of the third embodiment. The lens barrel 10B includes an outer fixed cylinder 101B that covers the outer periphery of the lens barrel 10B, a first inner fixed cylinder 102B positioned on the subject side inside the outer fixed cylinder 101B, and an inner side than the outer fixed cylinder 101B. And a second inner fixed cylinder 103A located on the image side.
Further, the lens barrel 10B is disposed between the outer fixed cylinder 101B and the second inner fixed cylinder 103B, and the vibration wave motor 12B fixed to the first inner fixed cylinder 102B by the fixing member 181 and the outer fixed cylinder 10B. And a vibration wave motor driving device 14 disposed in a holding portion 101a projecting inward from the inner peripheral side of the tube 101B. The vibration wave motor control device 14 is electrically connected to the vibration wave motor 12B and drives the vibration wave motor 12B.

  In addition, the first lens group L1 and the second lens group L2 are fixed to the first inner fixed cylinder 102B from the subject side, and the fourth lens group L4 is fixed to the second inner fixed cylinder 103B. Between the second lens group L2 and the fourth lens group L4, a third lens group L3 which is an AF lens for focusing held by the AF ring 187 is disposed. That is, the first lens group L1, the second lens group L2, the third lens group L3, and the fourth lens group L4 are sequentially arranged from the subject side to the image sensor side in the optical axis direction.

FIG. 12 is a diagram showing a configuration of a vibration wave motor 12B in the same embodiment. As shown in the figure, the vibration wave motor 12B includes a piezoelectric element 171 and a vibrator 170 composed of a metal elastic body 172 in contact with the piezoelectric element 171, and the elastic body 172 opposite to the contact surface with the piezoelectric element 171. Output projections 173a and 173b provided on the surface and a mover 174.
FIG. 13 is a diagram showing an operation of the vibration wave motor 12B in the same embodiment. When a pair of drive signals Sa and Sb are applied to the piezoelectric element 171 and the phase difference between the drive signals Sa and Sb is set to 90 degrees, as shown in FIG. 13, the protrusions 173a and 173b have excited longitudinal vibrations. And elliptical motion are produced by the combination with bending vibration. Since the protrusions 173a and 173b are in pressure contact with the moving element 174, a driving force is generated by friction. The protrusions 173a and 173b are made of a wear-resistant material to prevent frictional wear.

  Returning to FIG. 11, the vibrator 170 is supported by supporting the support pin 182 provided on the fixing member 181 with the notch 175 of the vibrator 170. The pressure member 183 is provided between the fixed member 181 and the vibrator 170, and brings the vibrator 170 into pressure contact with the moving element 174. The mover 174 is made of a light metal such as aluminum, and is in pressure contact with the protrusions 173a and 173b. The mover 174 is fixed to a linear guide 184 that is movable with respect to the linear rail 185 in the optical axis direction. The linear rail 185 is fixed to the outer peripheral side of the first inner fixed cylinder 102B along the optical axis direction. Thereby, the moving element 174 can move linearly with respect to the optical axis direction.

A fork 186 is attached to the mover 174, and the linear motion of the mover 174 is transmitted to the AF ring 187 via the fork 186. A guide portion 188 is provided in the AF ring 187. The guide portion 188 is movable along a straight rail 189 provided along the optical axis direction on the inner peripheral side of the first inner fixed cylinder 102B.
Thereby, the linear motion of the moving element 174 in the optical axis direction is transmitted to the AF ring 187, and the AF ring 187 can be moved in the optical axis direction.

In this embodiment, the lens barrel 10B includes a linear vibration wave motor 12B. However, the moving speed of the vibration wave motor 12B depends on the frequency, amplitude, and phase difference of the drive signals Sa and Sb. And the direction of movement can be controlled. Since the vibration wave motor control device 14 can perform the same control as the control performed on the vibration wave motor 12 of the first embodiment, the wobbling operation can be performed as in the first embodiment. it can.
Further, in the present embodiment, as in the second embodiment, the output of the vibration wave motor 12B can be transmitted to the cam ring 187 without using a gear, so that there is no rattling such as backlash of the gear. Smooth wobbling operation can be executed.
In addition, since there is no loss such as friction that occurs when the rotary motion used in the first embodiment and the second embodiment is converted into a linear motion, the energy use efficiency can be improved. Further, since the sliding surface of the AF ring 187 is reduced, noise generated by sliding can be reduced, and quiet driving is possible.

In the first to third embodiments described above, the operation for performing the insertion process after the voltages of the drive signals Sa and Sb have reached V ₁ has been described. However, the present invention is not limited thereto, and the drive signals Sa, voltage of Sb may perform a control to start the sweep process before reaching the V _1. Thereby, the time until the vibration wave motor starts driving can be shortened, and the responsiveness of the autofocus function can be improved.
In the first to third embodiments described above, the conversion table 141a is configured to store the two phase differences corresponding to the shooting information and the detection information. However, the present invention is not limited to this. In addition to the two phase differences, the frequencies of the drive signals Sa and Sb may be stored in the table 141a in association with the shooting information and the detection information. As a result, the rotational speed of the vibration wave motor 12 can be changed, and the speed of the wobbling operation can be determined according to the moving speed of the subject to improve the autofocus function during moving image shooting.

In the first to third embodiments described above, when the drive command signal is input, the control unit 141 controls the phase difference between the drive signals Sa and Sb output from the phase shift unit 143 to +90 degrees. However, the present invention is not limited to this, and any predetermined phase difference may be used.
In the first to third embodiments described above, the wobbling operation is performed by changing the phase difference between the drive signals Sa and Sb. However, the present invention is not limited to this, and the drive signal Sa is added to the phase difference. The wobbling operation may be performed by changing the amplitude (voltage) of Sb.

Further, when the electronic camera 1 captures a still image, the control unit 141 does not require a wobbling operation, and thus controls the vibration wave motor 12 using the frequencies of the drive signals Sa and Sb using a known technique. .
In the first to third embodiments described above, when the vibration wave motor 12 is stopped, the processing for driving the vibration wave motor 12 described above may be performed in the reverse order. Specifically, the control unit 141 stops the periodic change of the phase difference information, outputs frequency information indicating the drive frequency f0 to the oscillation unit 142, and sets the frequencies of the drive signals Sa and Sb to the vibration wave motor. The drive of the vibration wave motor 12 is stopped by setting the frequency outside the driveable frequency range. Thereafter, the control unit 141 decreases the amplitudes of the drive signals Sa and Sb to V ₀ [V] or less, and stops the amplification unit 144 from applying the drive signals Sa and Sb to the vibration wave motor 12. As a result, as in the case of driving the vibration wave motor 12, noise generated when the vibration wave motor 12 is stopped can be reduced and can be prevented from being detected by the built-in microphone 70.

  In the first to third embodiments described above, the control unit 141 may provide a conversion table 141a for each interchangeable lens (lens barrel 10) and provide a plurality of conversion tables. Each interchangeable lens has different lens characteristics, focal length, etc., so the wobbling operation itself can be determined according to the interchangeable lens, so that the optimal wobbling operation for the interchangeable lens can be performed. Can be improved.

  The control unit 141 described above may have a computer system inside. In this case, the process for executing the above-described wobbling operation is stored in a computer-readable recording medium in the form of a program, and the above-described process is performed by the computer reading and executing this program. . Here, the computer-readable recording medium means a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.

DESCRIPTION OF SYMBOLS 1 ... Electronic camera 10, 10A, 10B ... Lens barrel 12 ... Vibration wave motor 141 ... Control part 144 ... Amplification part 143 ... Phase shift part

Claims (8)

A vibration actuator that drives a focusing lens to focus the image of the subject;
An amplifier for applying a pair of amplified drive signals to the vibration actuator;
A phase shifter for changing a phase difference between the pair of drive signals;
A control unit that executes a first process for causing the phase shift unit to perform an operation of periodically changing a phase difference between the pair of drive signals when a signal instructing driving of the vibration actuator is input. A lens barrel characterized by The lens barrel according to claim 1,
The range of the phase difference between the pair of drive signals is determined according to the moving speed of the subject. The lens barrel according to claim 1 or 2, wherein
The frequency of the pair of drive signals is determined according to the moving speed of the subject. The lens barrel according to any one of claims 1 to 3, wherein
When a signal instructing driving of the vibration actuator is input, the control unit changes the amplitude of the pair of driving signals to a predetermined first amplitude before executing the first process. A second process to be applied to the vibration actuator, and an operation to increase the amplitude of the pair of drive signals to a predetermined second amplitude larger than the first amplitude after the second process. A third process to be performed by the amplifying unit;
The lens barrel characterized in that the time required for the second process is longer than the time required for the first process. The lens barrel according to any one of claims 1 to 4, wherein:
The controller is
When stopping the vibration actuator, the amplification unit is caused to stop the application of the pair of drive signals after the amplitude of the pair of drive signals is decreased from the second amplitude to the first amplitude. A lens barrel. The lens barrel according to any one of claims 1 to 5, wherein
A detection unit for detecting the position of the focusing lens;
The control unit determines whether or not the position of the focusing lens detected by the detection unit is positioned in the vicinity of the focusing position, and when the focusing lens is positioned in the vicinity of the focusing position, A lens barrel that causes the phase shifter to perform an operation of periodically changing a phase difference between a pair of drive signals. The lens barrel according to any one of claims 1 to 6, wherein
The lens barrel, wherein the focusing lens moves in the optical axis direction of the focusing lens without rotating. A vibration actuator that drives a focusing lens to focus the image of the subject;
An amplifier for applying a pair of amplified drive signals to the vibration actuator;
A phase shifter for changing a phase difference between the pair of drive signals;
A control unit that executes a first process for causing the phase shift unit to perform an operation of periodically changing a phase difference between the pair of drive signals when a signal instructing driving of the vibration actuator is input. An imaging apparatus characterized by the above.

Images