Patent Publication Number: US-2021184600-A1

Title: Driving control apparatus, driving control system, lens apparatus, driving control method, and memory medium

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a driving control apparatus, a driving control system, a lens apparatus, a driving control method, and a memory medium. 
     Description of the Related Art 
     A vibration actuator includes a vibrator that is made to generate vibration such as an elliptic motion by applying a two-phase frequency signal having a phase difference, and that is relatively moved with a contact body which contacts the vibrator. As methods for controlling driving of the vibration actuator, methods are known of a frequency control that changes a frequency of a two-phase frequency signal, and a phase difference control that changes the phase difference of the two-phase frequency signal. The frequency control and the phase difference control are often used to drive the vibration actuator at a high velocity and low velocity, respectively. 
     Japanese Patent Application Laid-Open No. (“JP”) 2014-153497 discloses a lens barrel in which when the phase difference is changed at times of starting driving, of reversing a driving direction, or of stopping the driving, a driving voltage is made lower than that when the vibration wave motor is normally driven, so as to suppress noise at a time of changing the phase difference. 
     However, in the lens barrel of JP 2014-153497, a ratio between an amplitude of the elliptic motion in a traveling direction and an amplitude of the elliptic motion in a direction vertical to the traveling direction changes according to the phase difference. Thus, as the phase difference decreases, the amplitude in the direction vertical to the traveling direction may relatively increases, and unnecessary vibration may occur. Although the frequency control can suppress vibration in the direction vertical to the traveling direction, power consumption may increase. 
     SUMMARY OF THE INVENTION 
     The present invention provides a driving control apparatus, a driving control system, a lens apparatus, a driving control method, and a memory medium each of which can suppress noise and unnecessary vibration and can reduce power consumption, when a vibration actuator is driven at a low velocity. 
     A driving control apparatus according to one aspect of the present invention controls an actuator that relatively moves a vibrator and a contact body contacting the vibrator, the vibrator being made to generate vibration by applying a first signal and a second signal having a phase difference. The driving control apparatus includes at least one processor or circuit configured to execute a plurality of tasks including a first determining task configured to determine the phase difference, and a second determining task configured to determine a voltage amplitude of power supplied to the actuator so that the voltage amplitude decreases as an absolute value of the phase difference decreases. 
     A driving control system including the above driving control apparatus, a driving control method corresponding the above driving control apparatus, and a storage medium storing a computer program that enables a computer to execute each task of the driving control apparatus also constitute another aspect of the present invention. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram illustrating a driving control system according to a first embodiment. 
         FIG. 2  is a configuration diagram illustrating a vibration actuator according to the first embodiment. 
         FIG. 3  is a diagram illustrating a relationship between a driving signal for the vibration actuator and a velocity according to the first embodiment. 
         FIGS. 4A and 4B  are diagrams illustrating an example of a relationship between a phase difference and a duty ratio according to the first embodiment. 
         FIG. 5  is a flowchart illustrating a method for driving the vibration actuator by controlling the phase difference according to the first embodiment. 
         FIG. 6  is a block diagram illustrating a driving control system according to a second embodiment. 
         FIG. 7  is a block diagram illustrating a lens interchangeable digital single lens reflex camera as an example of an image pickup apparatus according to the second embodiment. 
         FIGS. 8A and 8B  are diagrams illustrating an example of a relationship between a phase difference and a duty ratio according to the second embodiment. 
         FIG. 9  is a flowchart illustrating a method for driving a vibration actuator by a phase difference control according to the second embodiment. 
         FIG. 10  is a block diagram illustrating a driving control system according to a third embodiment. 
         FIGS. 11A to 11C  are diagrams illustrating an example of a relationship between a velocity, an acceleration, and a duty ratio according to the third embodiment. 
         FIG. 12  is a flowchart illustrating a method for driving a vibration actuator by a phase difference control according to the third embodiment. 
         FIG. 13  is a block diagram illustrating a driving control system according to a fourth embodiment. 
         FIGS. 14A and 14B  are diagrams illustrating an example of a relationship between a phase difference and a duty ratio according to the fourth embodiment. 
         FIG. 15  is a flowchart illustrating a method for driving a vibration actuator by a phase difference control according to the fourth embodiment. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Referring now to the accompanying drawings, a description will be given of embodiments according to the present invention. Corresponding elements in respective figures will be designated by the same reference numerals, and a description thereof will be omitted. 
     First Embodiment 
       FIG. 1  is a block diagram illustrating a driving control system  101  according to this embodiment. The driving control system  101  includes a driving control apparatus  102 , a detector  111 , and a vibration actuator  112 . 
       FIG. 2  is a block diagram illustrating the vibration actuator  112  according to this embodiment. The vibration actuator  112  includes a contact body  201  and a vibrator  205 . The contact body  201  and the vibrator  205  are pressurized and contact each other. The vibrator  205  includes a metal elastic body or the like  203  having a protrusion  202  and an electromechanical energy conversion element (piezoelectric element)  204  that is bonded to the metal elastic body or the like  203 . When a two-phase driving signal, which has a phase difference and changes periodically, is applied to the piezoelectric element  204 , the vibration of the elliptic motion is caused. The driving signal is a square wave signal, and a ratio of a pulse width of the square wave to one cycle is called a duty ratio. When the duty ratio increases, a voltage amplitude of power supplied to the vibration actuator  112  increases. When the duty ratio decreases, the voltage amplitude of the power supplied to the vibration actuator  112  decreases. 
     The vibration actuator  112  is driven at a low velocity by a phase difference control and at a high velocity by a frequency control.  FIG. 3  is a diagram illustrating a relationship between the driving signal for the vibration actuator  112  and the velocity. A horizontal axis represents a frequency and a vertical axis represents a velocity.  FIG. 3  illustrates three phase differences of 90 degrees, 60 degrees, and 30 degrees. During the phase difference control, the frequency is fixed to a start frequency and the vibration actuator  112  is driven by changing the phase difference. The phase difference is a value having a sign, and the sign indicates a traveling direction of the vibration actuator  112 . During the frequency control, the phase difference is fixed and the vibration actuator  112  is driven by changing the frequency from the start frequency. 
     In this embodiment, in a low velocity area where the velocity is v 301  or less, the phase difference control is performed in which the phase difference is −90 degrees to 90 degrees. In a high velocity area where the velocity is v 301  or more, the frequency control is performed in which the phase difference is fixed at 90 degrees or −90 degrees. In the frequency control, the phase difference may be set to another value. The voltage amplitude of the electric power supplied to the vibration actuator  112  is adjusted by the ratio of the pulse width, that is, the duty ratio. The voltage amplitude may be adjusted by a method other than a pulse width modulation method. Other than the pulse width modulation method, a linear method may be used as a method for adjusting the voltage amplitude. In the following description, an example is described of adjusting the voltage amplitude by adjusting the duty ratio, but the duty ratio may be simply read as the voltage amplitude. 
     The vibration actuator  112  moves in an x direction of  FIG. 2 . 
     The driving control apparatus  102  includes a controller  103 , a signal generator  108 , and a driving circuit  109 . The detector  111  includes a position sensor configured to detect a position of the vibration actuator  112 . The position sensor is an optical encoder including an optical scale having a striped pattern and an optical sensor that receives light emitted from a light emitter and reflected by the optical scale. 
     The controller  103  includes a CPU and the like, is configured to periodically execute various processing, and is configured to control the frequency, the phase difference, the duty ratio, and the like of the two-phase driving signal (first signal and second signal) applied to the vibration actuator  112 . The controller  103  includes a target value input unit  104 , a control amount calculator  105 , a phase difference frequency determiner  106  as a first determiner, a duty ratio determiner  107  as a second determiner, and a position calculator  110 . 
     The target value input unit  104  is configured to set a target position to which the vibration actuator  112  moves. The target position is an instruction value that changes with time, and is calculated periodically until the vibration actuator  112  moves to a final stop position. 
     The position calculator  110  is configured to calculate position information on a position of the vibration actuator  112  by using a digital signal that is acquired by an AD converter converting an analog signal output from the detector  111 . 
     The control amount calculator  105  is configured to calculate a control amount by using PID control based on a difference between the target position of the vibration actuator  112  periodically acquired from the target value input unit  104  and a current position of the vibration actuator  112  input from the position calculator  110 . P represents proportional control, I represents integral control, and D represents differential control. 
     The phase difference frequency determiner  106  is configured to determine the frequency and the phase difference of the two-phase driving signal for controlling the driving of the vibration actuator  112 , by using the control amount calculated by the control amount calculator  105 . 
     The duty ratio determiner  107  is configured to determine the duty ratio according to the phase difference determined by the phase difference frequency determiner  106 . By determining the duty ratio, the voltage amplitude is determined of the power supplied to the vibration actuator  112 . 
     The signal generator  108  is configured to generate the two-phase driving signal based on the frequency, phase difference, and duty ratio each of which are set by the controller  103 , and is configured to output the two-phase driving signal to the driving circuit  109 . 
     Since the two-phase driving signal acquired from the signal generator  108  is insufficient for driving the vibration actuator  112 , the driving circuit  109  performs voltage amplification and power amplification and applies it to the vibration actuator  112 . 
     Hereinafter, a method will be described of determining the duty ratio according to the phase difference with reference to  FIGS. 4A and 4B .  FIGS. 4A and 4B  are diagrams illustrating an example of a relationship between the phase difference and the duty ratio. In  FIG. 4A , a horizontal axis represents the control amount calculated by the control amount calculator  105 , and a vertical axis represents the phase difference. In  FIG. 4B , a horizontal axis represents the control amount calculated by the control amount calculator  105 , and a vertical axis represents the duty ratio. 
     When the control amount is a value (=zero) indicated by a dotted line  401 , the phase difference is zero. At this time, the duty ratio is d 41 . The phase difference increases as the control amount increases from zero. As the phase difference increases, the duty ratio increases in a linear relationship. The duty ratio is d 42  when the control amount is a value indicated by a dotted line  403 . When the control amount becomes larger than the value indicated by the dotted line  403 , the driving control apparatus  102  shifts the driving control method of the vibration actuator  112  from the phase difference control to the frequency control. In the frequency control, the phase difference is constant at 90 degrees, and the duty ratio is also constant at d 42 . 
     As the control amount decreases from zero, the phase difference decreases and takes a negative value. The sign of the phase difference indicates the traveling direction, and a negative value of the phase difference indicates that the traveling direction is in an opposite direction. When the phase difference is negative, the duty ratio is determined according to the absolute value of the phase difference. That is, the duty ratio increases as the phase difference decreases. The duty ratio is d 42  when the control amount takes a value indicated by a dotted line  402 . When the control amount becomes smaller than the value indicated by the dotted line  402 , the driving control apparatus  102  shifts the driving control method of the vibration actuator  112  from the phase difference control to the frequency control. In the frequency control, the phase difference is constant at −90 degrees, and the duty ratio is also constant at d 42 . 
     As described above, in this embodiment, the duty ratio decreases as the absolute value of the phase difference decreases. That is, the voltage amplitude of the power supplied to the vibration actuator  112  decreases as the absolute value of the phase difference decreases. 
     As the absolute value of the phase difference decreases, a vibration component increases of the elliptic motion in the direction (y direction in  FIG. 2 ) vertical to the traveling direction (x direction in  FIG. 2 ) of the vibration actuator  112 . In this embodiment, as the absolute value of the phase difference decreases, the duty ratio decreases, that is, the voltage amplitude decreases, so that the vibration component of the elliptic motion can be suppressed in the direction vertical to the traveling direction. By suppressing the vibration component in the direction vertical to the traveling direction, noise and unnecessary vibration can be suppressed, and power consumption can be reduced. 
     Hereinafter, a flow will be described of determining the phase difference and duty ratio and outputting the driving signal, when the vibration actuator  112  is moved to the final stop position, that is a final target position, by the phase difference control with reference to  FIG. 5 .  FIG. 5  is a flowchart illustrating a method for driving the vibration actuator  112  by the phase difference control according to this embodiment. In the phase difference control, the frequency is fixed to the start frequency, as described above. 
     In step S 501 , the target value input unit  104  sets the target position to which the vibration actuator  112  moves. 
     In step S 502 , the controller  103  calculates a difference, that is a deviation, between the target position to which the vibration actuator  112  moves and the position of the vibration actuator  112  acquired from the position information detected by the detector  111 . 
     In step S 503 , the control amount calculator  105  calculates the control amount using the PID control based on the difference calculated in step S 502 . 
     In step S 504 , the phase difference frequency determiner  106  determines the phase difference from the control amount calculated in step S 503 . 
     In step S 505 , the duty ratio determiner  107  determines the duty ratio according to the phase difference determined in step S 504 , by using the relationship illustrated in  FIG. 4A and 4B . In this embodiment, the relationship illustrated in  FIG. 4A and 4B  is used, but a relationship may be used that is different from the relationship illustrated in  FIG. 4A and 4B . 
     In step S 506 , the signal generator  108  generates the two-phase driving signal having phase difference based on the phase difference, the frequency, and the duty ratio, and outputs the two-phase driving signal to the driving circuit  109 . The controller  103  stores, as set values, the phase difference, the frequency, and the duty ratio. 
     As described above, when driving the vibration actuator  112  at low speed, this embodiment can suppress noise and unnecessary vibration while reducing the power consumption, by controlling the duty ratio according to the phase difference. 
     Second Embodiment 
       FIG. 6  is a block diagram illustrating a driving control system  101  according to this embodiment. A controller  103  of this embodiment includes a phase difference duty ratio interlocking control execution determiner  601 . The phase difference duty ratio interlocking control execution determiner  601  is configured to determine whether or not to determine the duty ratio according to the phase difference, depending on a situation in which the vibration actuator  112  is operated, or depending on an operation mode in which the vibration actuator  112  is to be operated. Since the other configurations of the driving control system  101  of this embodiment are the same as the configurations of the driving control system  101  of the first embodiment, detailed description thereof will be omitted. 
       FIG. 7  is a block diagram illustrating a lens interchangeable digital single lens reflex camera, which is an example of an image pickup apparatus having a driving control system  101 . In this embodiment, the driving control system  101  is used to drive a focus lens unit  753  as an optical unit described later. The digital single lens reflex camera includes a digital single lens reflex camera main body  701  and a lens apparatus  750 . The digital single lens reflex camera main body  701  is mechanically and electrically connected to the lens apparatus  750 , and supplies power to the lens apparatus  750  via a power supply terminal. 
     First, the configuration will be described of the digital single lens reflex camera main body  701 . 
     An image pickup unit  704  is an image sensor including a CCD, CMOS, or the like, and is configured to convert, into an electric signal, an optical image in which a light amount is adjusted by a shutter  703 . An A/D converter  705  is configured to convert an analog signal output from the image pickup unit  704  into a digital signal. An image processor  708  is configured to perform pixel interpolation, resizing processing, or color conversion processing on the data from the A/D converter  705  or the data from a memory controller  709 . The image processor  708  is configured to perform predetermined calculation processing using captured still image data. A camera system controller  702  is configured to perform an exposure control and a focus detection control using a calculation result acquired from the image processor  708 . AF (autofocus) processing, AE (auto-exposure) processing, and EF (pre-flash) processing are performed of a TTL (through-the-lens) method. The image processor  708  performs the predetermined calculation processing using the captured still image data, and to perform AWB (auto white balance) processing of the TTL method based on an acquired calculation result. 
     The output data from the A/D converter  705  is written on a memory  710  via the image processor  708  and the memory controller  709 , or the memory controller  709 . The memory  710  is configured to store the still image data from the A/D converter  705  and still image data for display that is to be displayed on a display  707 . The memory  710  also serves as a memory (video memory) for displaying a still image. A D/A converter  706  is configured to convert the still image data for display stored on the memory  710  into an analog signal and to supply it to the display  707 . The still image data for display stored on the memory  710  is displayed on the display  707  via the D/A converter  706 . 
     The display  707  is a display such as an LCD, and is configured to perform display according to the analog signal from the D/A converter  706 . The A/D converter  705  performs an A/D conversion on a digital signal. The memory  710  accumulates the digital signal. Thereafter, the digital signal is analog-converted by the D/A converter  706 , is sequentially transmitted to the display  707 , and is displayed, so that a through still image can be displayed, that is, live view display can be performed. 
     A nonvolatile memory  712  is a memory as a recording medium that is capable of electric erasing and recording, and is, for example, an EEPROM or the like. The nonvolatile memory  712  stores a constant, program, and the like for operation of the camera system controller  702 . 
     The camera system controller  702  includes at least one CPU or circuit and is configured to control the entire digital single lens reflex camera. The camera system controller  702  is configured to execute a program recorded on the nonvolatile memory  712 . A system memory  711  is, for example, a RAM. In the system memory  711 , a constant, a variable, a program read from the nonvolatile memory  712 , and the like are expanded for operation of the camera system controller  702 . The camera system controller  702  is configured to control display by controlling the image processor  708 , the memory controller  709 , and the memory  710 . 
     An operation unit  713 , a shutter button  715 , and a mode selecting switch  716  are operation units for inputting various operation instructions to the camera system controller  702 . By operating the mode selecting switch  716 , the operation mode of the camera system controller  702  can be switched to any one of a still image pickup mode, a motion image pickup mode, a playback mode, and the like. The modes included in the still image recording mode are, for example, an auto image pickup mode, an auto scene discrimination mode, a manual mode, various scene modes of image pickup settings for various image pickup scenes, a program AE mode, and a custom mode. 
     A first shutter switch  720  is turned on by a so-called half-depression as an image pickup preparation instruction in the middle of the operation of the shutter button  715 , and a first shutter switch signal SW 1  is generated. When the first shutter switch signal SW 1  is generated, operations start such as AF processing, AE processing, AWB processing, and EF processing. 
     A second shutter switch  721  is turned by a so-called full-depression as an image pickup instruction when operation on the shutter button  715  is completed, and a second shutter switch signal SW 2  is generated. When the second shutter switch signal SW 2  is generated, the camera system controller  702  starts a series of operations on image pickup processing from reading the signal from the image pickup unit  704  to writing the still image data on the recording medium  724 . 
     When various function icons displayed on the display  707  are selected and operated, each operation member of the operation unit  713  is assigned to a function properly for each scene, and acts as various function buttons. 
     A power switch  717  is an operating unit configured to switch power ON/OFF of the digital single lens reflex camera main body  701 . A power controller  718  includes a battery detection circuit, a DC-DC converter, a switch circuit for switching a block to be energized, and the like, and to detect whether or not a battery is installed, a type of battery, and a remaining battery level. The power controller  718  is configured to control a DC-DC converter based on a detection result, and an instruction from the camera system controller  702 , and to supply required voltage to each unit including the recording medium  724  for a required period. The power supply unit  719  includes a primary battery such as an alkaline battery and a lithium battery, a secondary battery such as an NiCd battery, an NiMH battery, and a Li battery, an AC adapter, and the like. 
     A recording medium I/F  723  is an interface with a recording medium  724  such as a memory card or a hard disk. The recording medium  724  is a recording medium such as a memory card for recording a captured still image, and includes a semiconductor memory, an optical disk, a magnetic disk, or the like. 
     A camera communicator  714  is configured to give a desired operation instruction such as an instruction for driving a focus lens and a diaphragm to the lens apparatus  750  via a lens communicator  759 , and is configured to transmit/receive necessary information. 
     Next, a configuration of the lens apparatus  750  will be described. 
     The lens apparatus  750  includes an image pickup optical system having a diaphragm  752 , a focus lens unit  753 , a zoom lens unit  754 , and a front lens unit  755 . 
     A lens system controller  751  is a computer including a CPU or the like, and is configured to control the entire lens apparatus  750  including a diaphragm driver  756 , a focus driver  757 , a focal length detector  758 , the lens communicator  759 , and a memory  760 . The lens system controller  751  is configured to transmit/receive information to/from the digital single lens reflex camera main body  701  via the lens communicator  759 . 
     The diaphragm driver  756  is configured to control an aperture diameter of the diaphragm  752  according to an instruction from the lens system controller  751  and to perform a light amount adjustment operation. 
     The focus driver  757  includes the driving control system  101 , and is configured to drive the focus lens unit  753  in an optical axis direction, as an x direction, according to an instruction from the lens system controller  751  so as to adjust the focus. 
     An operation switch  763  includes a manual operation switch for zooming, focusing, and a diaphragm, and a setting switch for switching automatic/manual. 
     A focal length detector  758  is configured to detect a focal length of the image pickup optical system by detecting a position of the zoom lens unit  754  using a zoom position sensor such as a variable resistor. 
     A memory  760  includes a ROM, RAM, or the like, and is configured to store a product model number, a serial number, focal length information, focus sensitivity information, and the like of the lens apparatus  750 . 
     A temperature detector  761  can detect an environment in which the lens apparatus  750  is used. 
     An orientation detector  762  is configured to detect an orientation, that is, a position, of the lens apparatus  750  relative to a gravity direction as a y direction. An acceleration sensor or the like can be used as the orientation detector  762 . Based on the orientation detected by the orientation detector  762 , it is possible to determine whether the lens apparatus  750  is in a horizontal state or in a vertical state. 
     For example, when the shutter button  715  is half-depressed and operation is performed for detecting focus, the camera system controller  702  transmits a driving instruction for the focus lens unit  753  to the lens system controller  751  via the camera communicator  714  and via the lens communicator  759 . The driving instruction for the focus lens unit  753  is a moving amount of the focus lens unit  753  to an in-focus position and a velocity of the focus lens unit  753  when the focus lens unit  753  moves, each of which is calculated from a defocus amount corresponding to a phase difference of a signal of an object image. When the lens system controller  751  receives the driving instruction for the focus lens unit  753 , the lens system controller  751  moves the focus lens unit  753  to the in-focus position via the focus driver  757 . The lens system controller  751  transmits information on the image pickup mode to the focus driver  757 . 
     In the following description, a driving control for the focus lens unit  753  will be described in a case where the still image pickup mode or the motion image pickup mode is selected by using the mode selecting switch  716 . The image pickup mode selected by the mode selecting switch  716  is transmitted to the lens apparatus  750  via the camera communicator  714  and the lens communicator  759 . The still image pickup mode requires a wide velocity area from a low velocity to a high velocity. In the motion image pickup mode, the velocity may be relatively low, but quietness is required. 
     The control will be described of the duty ratio relative to the phase difference according to the image pickup mode.  FIG. 8  is a diagram illustrating an example of a relationship between the phase difference and the duty ratio of this embodiment. Since the relationship between the phase difference and the duty ratio in the still image pickup mode is the same as the relationship illustrated in  FIG. 4A and 4B  described in the first embodiment, detailed description thereof will be omitted. In the motion image pickup mode, the duty ratio is not controlled according to the phase difference, and thus the duty ratio is constant at d 81  regardless of the phase difference. 
       FIG. 9  is a flowchart illustrating a method of driving the vibration actuator  112  by a phase difference control of this embodiment. In this embodiment, a part different from the sequence of  FIG. 5  will be described. 
     The lens system controller  751  moves the focus lens unit  753  to the in-focus position via the focus driver  757 , and transmits information on the image pickup mode to the focus driver  757 . 
     In step S 901 , the phase difference duty ratio interlocking control execution determiner  601  determines whether or not to determine the duty ratio according to the phase difference, according to the image pickup mode. When the still image pickup mode is set, it is determined that the duty ratio is determined according to the phase difference, and the process proceeds to step S 505 . When the motion image pickup mode is set, it is determined that the duty ratio is not determined according to the phase difference, and the process proceeds to step S 902 . 
     In step S 902 , the duty ratio determiner  107  determines the duty ratio regardless of the phase difference. 
     As described above, according to the configuration of this embodiment, in addition to the effect of the first embodiment, the vibration actuator  112  can be properly driven by selecting the relationship between the phase difference and the duty ratio according to the operation mode. 
     When the motion image pickup mode is set, this embodiment determines the duty ratio regardless of the phase difference, but the duty ratio may be determined according to the phase difference. In this case, a minimum value of the duty ratio is set to be smaller than a minimum value of the duty ratio in the image pickup mode. 
     This embodiment determines whether or not the duty ratio is determined according to the phase difference, according to the image pickup mode. However, 
     the present invention is not limited to this. An operation instruction for the vibration actuator  112  may be used for the determination. For example, an instruction value may be used for the determination, the instruction value relating to the moving amount to the final target position given to the vibration actuator  112 . Specifically, when the instruction value for the moving amount is smaller than a predetermined value, the duty ratio may be not determined according to the phase difference. When the instruction value for the moving amount is larger than the predetermined value, the duty ratio may be determined according to the phase difference. The determination may be performed by using an instruction value relating to a velocity of the vibration actuator  112 . When the instruction value relating to the velocity of the vibration actuator  112  is larger than a predetermined value, the duty ratio may not be determined according to the phase difference. When the instruction value relating to the velocity of the vibration actuator  112  is smaller than the predetermined value, the duty ratio may be determined according to the phase difference. 
     Third Embodiment 
       FIG. 10  is a block diagram of a driving control system  101  of this embodiment. Stopping accuracy is required while unnecessary vibration is suppressed, when the focus lens unit  753  is driven at low velocity. However, the stopping accuracy may deteriorate due to frictional force or the like. In this embodiment, the controller  103  includes a deceleration state determiner  1001  configured to determine an operation state of the vibration actuator  112 , so that the vibration actuator  112  stops at a stop position with high accuracy. The controller  103  is configured to use a determination result of the deceleration state determiner  1001  to determine whether or not it is necessary to make the vibration actuator  112  decelerate from a current velocity. Since the other configurations of the driving control system  101  of this embodiment are the same as the configurations of the driving control system  101  of the first embodiment, detailed description thereof will be omitted. Since the configuration of the digital single lens reflex camera having the driving control system  101  of this embodiment is the same as the configuration of the digital single lens reflex camera of the second embodiment, detailed description thereof will be omitted. 
       FIGS. 11A to 11C  are diagrams illustrating an example of a relationship between a velocity, acceleration, and duty ratio of this embodiment. In each of  FIGS. 11A to 11C , a horizontal axis represents time. The vibration actuator  112  starts driving at time t 1 , reaches velocity v 111  at time t 2 , starts deceleration at time t 3 , and stops at a final target position at time t 4 . From the time t 1  to t 2 , acceleration of the vibration actuator  112  is set to a 111  so that the velocity increases to velocity v 111 . From the time t 1  to t 2 , the duty ratio is increased from d 41  to d 42 . From the time t 2  to t 3 , the acceleration of the vibration actuator  112  is set to zero. Thereby, the vibration actuator  112  is driven at a constant velocity, and the phase difference also takes a constant value. From time t 3  to t 4 , the acceleration of the vibration actuator  112  is set to −a 111  so that the vibration actuator decelerates. From the time t 3  to t 4 , the duty ratio is maintained at d 42  without being updated. 
       FIG. 12  is a flowchart illustrating a method of driving the vibration actuator  112  by a phase difference control of this embodiment. In this embodiment, part different from the sequence of  FIG. 5  will be described. 
     In step S 1201 , the deceleration state determiner  1001  determines the operation state of the vibration actuator  112 . In this embodiment, when the acceleration of the vibration actuator  112  is negative, it is determined that the operation state of the vibration actuator  112  is in a deceleration state. When the acceleration of the vibration actuator  112  is not negative, it is determined that the operation state of the vibration actuator  112  is not in the deceleration state. 
     In step S 1202 , the controller  103  determines whether or not it is necessary to make the vibration actuator  112  decelerate, based on the operation state of the vibration actuator  112  determined in step S 1201 . When the vibration actuator  112  is in the deceleration state and it is necessary to make the vibration actuator  112  decelerate, the process proceeds to step S 505 . When the vibration actuator  112  is not in the deceleration state and it is not necessary to make the vibration actuator  112  decelerate, the process proceeds to step S 1203 . 
     In step  1203 , the duty ratio determiner  107  determines the value currently held as the duty ratio regardless of the phase difference, that is, the value of the duty ratio is maintained. 
     As described above, the configuration of this embodiment can stop the vibration actuator  112  with high accuracy in addition to the effect of the first embodiment. 
     Fourth Embodiment 
       FIG. 13  is a block diagram illustrating a driving control system  101  of this embodiment. The controller  103  of this embodiment includes a phase difference duty ratio interlocking control relationship determiner  1301 . The phase difference duty ratio interlocking control relationship determiner  1301  is configured to select a proper relationship from a plurality of relationships between the phase difference and the duty ratio according to a state in which the digital single lens reflex camera is used. In this embodiment, the phase difference duty ratio interlocking control relationship determiner  1301  selects a relationship between the phase difference and the duty ratio by using information from the orientation detector  762  of the lens apparatus  750 . Since the other configurations of the driving control system  101  of this embodiment are the same as the configurations of the driving control system  101  of the first embodiment, detailed description thereof will be omitted. Since the configuration of the digital single lens reflex camera including the driving control system  101  of this embodiment is the same as the configuration of the digital single lens reflex camera of the second embodiment, detailed description thereof will be omitted. 
     A driving direction (x direction in  FIG. 2 ) of the vibration actuator  112  is parallel to an optical axis direction (x direction in  FIG. 7 ), the optical axis direction being a driving direction of the focus lens unit  753 . The driving direction of the vibration actuator  112  is vertical to the gravity direction, that is the y direction in  FIG. 7 . When the driving direction of the vibration actuator  112  is vertical to the gravity direction, the vibration actuator  112  is easily affected by gravity, and it may be difficult to stop the driving of the focus lens unit  753 . Thus, in this embodiment, a relationship between the phase difference and the duty ratio is changed according to the orientation of the lens apparatus  750  at a time of use, specifically, by comparing an angle θ for the x direction in  FIG. 7  and a threshold value θt. 
       FIGS. 14A and 14B  are diagrams each illustrating an example of a relationship between the phase difference and the duty ratio of this embodiment. When the angle θ is smaller than the threshold value θt, the duty ratio changes based on a first relationship. Since the first relationship is the same as the relationship illustrated in  FIG. 4A and 4B  described in the first embodiment, detailed description thereof will be omitted. When the angle θ is larger than the threshold value θt, the duty ratio changes based on a second relationship. In the second relationship, when a control amount is at a value (=zero) indicated by a dotted line  401 , the duty ratio is d 141  larger than d 41  which is a minimum value of the duty ratio in the first relationship. As the control amount increases from zero, the duty ratio increases in a linear relationship. The duty ratio is d 42  when the control amount is a value indicated by the dotted line  403 . When the control amount becomes larger than the value indicated by the dotted line  403 , the driving control apparatus  102  shifts a driving control method of the vibration actuator  112  from the phase difference control to the frequency control. In the frequency control, the phase difference is constant at 90 degrees, and the duty ratio is also constant at d 42 . As the control amount decreases from zero, the phase difference decreases and becomes a negative value. A sign of the phase difference indicates the traveling direction, and a negative value of the phase difference indicates that the traveling direction is in an opposite direction. When the phase difference is negative, the duty ratio is determined according to the absolute value of the phase difference. That is, the duty ratio increases as the phase difference decreases. The duty ratio is d 42  when the control amount is a value indicated by a dotted line  402 . When the control amount becomes smaller than the value indicated by the dotted line  402 , the driving control apparatus  102  shifts the driving control method of the vibration actuator  112  from the phase difference control to the frequency control. In the frequency control, the phase difference is constant at −90 degrees, and the duty ratio is also constant at d 42 . 
       FIG. 15  is a flowchart illustrating a method of driving the vibration actuator  112  by a phase difference control of this embodiment. In this embodiment, part different from the sequence of  FIG. 5  will be described. 
     The lens system controller  751  moves the focus lens unit  753  to the in-focus position via the focus driver  757 , and transmits orientation information (angle θ) of the lens apparatus  750  to the focus driver  757 . 
     In step S 1501 , the phase difference duty ratio interlocking control relationship determiner  1301  determines whether or not to control the duty ratio according to the phase difference, by using the orientation information (angle θ) of the lens apparatus  750  acquired from the lens system controller  751 . When the angle θ is smaller than the threshold value θt, the process proceeds to step S 1502 . When the angle θ is larger than the threshold value θt, the process proceeds to step S 1503 . It is possible to arbitrarily set which step to proceed when the angle θ is equal to the threshold value θt. 
     In step S 1502 , the duty ratio determiner  107  determines the duty ratio according to the phase difference determined in step S 504  by using the first relationship illustrated in  FIGS. 14A and 14B . 
     In step S 1503 , the duty ratio determiner  107  determines the duty ratio according to the phase difference determined in step S 504  using the second relationship illustrated in  FIGS. 14A and 14B . 
     As described above, according to the configuration of this embodiment, it is possible to stop the vibration actuator  112  with high accuracy in addition to the effect of the first embodiment. 
     In this embodiment, the duty ratio is controlled according to the phase difference even when the orientation information (angle θ) is larger than the threshold value θt, but the duty ratio may not be controlled, that is, the duty ratio may be determined regardless of the phase difference. 
     In this embodiment, the phase difference duty ratio interlocking control relationship determiner  1301  selects the relationship between the phase difference and the duty ratio according to the orientation of the lens apparatus  750  as the state in which the digital single lens reflex camera is used. However, the present invention is not limited to this. For example, in a low temperature environment, when grease or the like is used to a driven member, a load acting on the vibration actuator  112  may change due to a change in viscosity. The relationship between the phase difference and the duty ratio may be selected according to a temperature environment in which the digital single lens reflex camera is used. In this case, the relationship between the phase difference and the duty ratio may be selected using information from the temperature detector  761 . That is, when a value indicating the temperature environment from the temperature detector  761  is larger than a predetermined value, the first relationship may be used, and when the value indicating the temperature environment from the temperature detector  761  is smaller than the predetermined value, the second relation may be used. 
     In addition to the temperature, humidity may be used to determine the relationship between the phase difference and the duty ratio. For example, in a high humidity environment, friction may change and the stopping accuracy may deteriorate. When a value indicating the humidity environment from a humidity detector (not illustrated) is smaller than a predetermined value, the first relationship may be used. When the value indicating the humidity environment from the humidity detector is larger than the predetermined value, the second relation may be used. 
     The above embodiments can provide a driving control apparatus, a driving control system, a lens apparatus, a driving control method, and a memory medium each of which can suppress noise and unnecessary vibration and can reduce power consumption, when the vibration actuator is driven at low velocity. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Application No. 2019-224307, filed on Dec. 12, 2019 which is hereby incorporated by reference herein in its entirety.