JP7511195B1 - Drive module, imaging device and interchangeable lens - Google Patents

Abstract

[Problem] To provide a drive module etc. capable of recovering from motor out-of-step with high accuracy. [Solution] A drive module for driving an element in an imaging device includes a motor that drives the element, a motor drive unit that controls the excitation of the motor, a position detection unit that detects the position of the element, and a control unit that controls the motor drive unit and manages the position of the element. The control unit detects out-of-step when the difference between the position of the element detected by the position detection unit and the position of the element managed by the control unit is greater than a predetermined value while driving by the motor is stopped. When out-of-step is detected, the control unit controls the motor drive unit to eliminate the out-of-step by using a magnetic field having the same pattern as the magnetic field pattern controlled when the motor was stopped. [Selected Figure] Figure 4

Description

The present disclosure relates to a drive module for driving elements in an imaging device, as well as an imaging device and an interchangeable lens equipped with the drive module.

Patent Document 1 discloses a sewing machine that aims to perform control to prevent step-out of the pulse motor by detecting the amount of movement of the driven part even when the pulse motor is stopped. The sewing machine of Patent Document 1 moves the target position closer to the current position so that the difference between the target position of the driven part and the current position based on the detected amount of movement is equal to or less than the step-out limit value, i.e., so as not to cause step-out. The sewing machine then sets the target position to the stop position where the pulse motor stopped when driving ended, and controls the pulse motor to return the current position to the stop position. By performing such feedback control of the pulse motor, step-out is prevented even when there is a possibility of step-out occurring due to the application of an external force.

JP 2006-000393 A

This disclosure provides a drive module, an imaging device, and an interchangeable lens that can accurately recover from a motor losing synchronization.

A drive module according to one aspect of the present disclosure drives an element in an imaging device. The drive module includes a motor that drives the element, a motor drive unit that controls the excitation of the motor, a position detection unit that detects the position of the element, and a control unit that controls the motor drive unit to manage the position of the element. The control unit detects out-of-step when the difference between the position of the element detected by the position detection unit and the position of the element managed by the control unit is greater than a predetermined value while driving by the motor is stopped. When out-of-step is detected, the control unit controls the motor drive unit to eliminate the out-of-step by using a magnetic field having the same pattern as the magnetic field pattern controlled when the motor was stopped.

An imaging device according to one aspect of the present disclosure includes a driving module according to the present disclosure, an imaging section that captures a subject image formed via an optical system, and an element in at least one of the optical system and the imaging section that is driven by the driving module.

An interchangeable lens according to one aspect of the present disclosure is an interchangeable lens that can be attached to a camera body in an imaging device, and includes a drive module according to the present disclosure and an optical system that includes an element driven by the drive module.

The drive module, imaging device, and interchangeable lens disclosed herein enable the motor to recover from loss of synchronization with high precision.

FIG. 1 is a block diagram showing a configuration of a digital camera according to a first embodiment of the present disclosure. FIG. 2 is a diagram illustrating an example of the configuration of a drive module in the digital camera of the first embodiment; FIG. 1 is a diagram for explaining the operation of a drive module. 1 is a flowchart illustrating an operation of a driving module according to the first embodiment; A timing chart for explaining a recovery operation from a loss of synchronism caused by excitation of the drive module of the first embodiment. FIG. 13 is a diagram for explaining the operation during step-out when the drive module of the first embodiment does not return to normal due to excitation; A timing chart for explaining a recovery operation from a step-out depending on a return position of the drive module according to the first embodiment. FIG. 7 is a diagram for explaining the operation of the driving module from the state of FIG. 6(B). 11 is a flowchart illustrating the operation of a driving module according to a second embodiment. 11 is a timing chart for explaining the operation of the driving module according to the second embodiment. FIG. 13 is a diagram illustrating a configuration of a drive module according to a third embodiment; FIG. 13 is a diagram for explaining an encoder correction position in the drive module of the third embodiment;

Below, embodiments of the present disclosure will be described with appropriate reference to the drawings. However, in the detailed description, unnecessary parts of the description of the prior art and substantially identical configurations may be omitted. This is for the sake of simplicity. In addition, the following description and the accompanying drawings are disclosed so that a person skilled in the art can fully understand the present disclosure, and are not intended to limit the subject matter of the claims.

(Embodiment 1)
In the first embodiment, a digital camera will be described as an example of an imaging device including a drive module according to the present disclosure.

1 is a block diagram showing the configuration of a digital camera 1 according to embodiment 1. The digital camera 1 is made up of a camera body 100 and an interchangeable lens 200 that is detachable from the camera body 100.

1-1. Camera Body The camera body 100 comprises an image sensor 110, a liquid crystal monitor 120, an operation unit 130, a camera control unit 140, a RAM 141, a ROM 142, a body mount 150, a card slot 170, and a shutter 180.

The camera control unit 140 controls the operation of the entire digital camera 1 by controlling components such as the image sensor 110 in response to instructions from the release button. The camera control unit 140 transmits a vertical synchronization signal to a timing generator (TG) 112. In parallel with this, the camera control unit 140 generates an exposure synchronization signal. The camera control unit 140 periodically transmits the generated exposure synchronization signal to the lens control unit 240 via the body mount 150 and the lens mount 250. The camera control unit 140 uses the RAM 141 as a working memory during control operations and image processing operations.

The image sensor 110 is an example of an imaging element that captures an image of a subject incident through the interchangeable lens 200 and generates image data. The image sensor 110 is, for example, a CCD, a CMOS image sensor, or an NMOS image sensor. The generated image data is digitized by an AD converter (ADC) 111. The digitized image data is subjected to a predetermined image processing by the camera control unit 140. The predetermined image processing is, for example, gamma correction processing, white balance correction processing, scratch correction processing, YC conversion processing, electronic zoom processing, and/or JPEG compression processing.

The image sensor 110 operates at a timing controlled by the timing generator 112. The image sensor generates still images, moving images, or through images for recording. The through images are mainly moving images, and are displayed on the LCD monitor 120 so that the user can decide the composition for capturing a still image.

The LCD monitor 120 displays images such as through images and various information such as menu screens. The LCD monitor 120 is an example of a display unit in this embodiment. Instead of the LCD monitor, other types of display devices, for example, an organic EL display device, may be used.

The operation unit 130 includes various operation members such as a release button for instructing the camera to start shooting, a mode dial for setting the shooting mode, and a power switch. The operation unit 130 also includes a touch panel that is superimposed on the LCD monitor 120.

RAM 141 is a recording medium that functions as a work memory for camera control unit 140. RAM 141 is realized by a DRAM (Dynamic Random Access Memory) or the like. RAM 141 temporarily stores (i.e. holds) image data generated by image sensor 110, various setting information for digital camera 1, and the like. ROM 142 is a non-volatile recording medium. ROM 142 is realized by a flash memory or the like. For example, ROM 142 stores predetermined setting values for digital camera 1, and the like.

The card slot 170 can accommodate a memory card 171 and controls the memory card 171 under control of the camera control unit 140. The digital camera 1 can store image data in the memory card 171 and read image data from the memory card 171.

The shutter 180 adjusts the exposure time of light incident on the image sensor 110. The shutter 180 is driven by a drive system such as a DC motor or a stepping motor in accordance with a control signal issued from the camera control unit 140. For example, the camera control unit 140 can control the drive speed (shutter speed or continuous shooting speed) at which the shutter 180 is driven.

The body mount 150 can be mechanically and electrically connected to the lens mount 250 of the interchangeable lens 200. The body mount 150 can transmit and receive data to and from the interchangeable lens 200 via the lens mount 250. The body mount 150 transmits an exposure synchronization signal received from the camera control unit 140 to the lens control unit 240 via the lens mount 250. In addition, the body mount 150 transmits other control signals received from the camera control unit 140 to the lens control unit 240 via the lens mount 250. In addition, the body mount 150 transmits signals received from the lens control unit 240 to the camera control unit 140 via the lens mount 250.

The camera body 100 also includes a gyro sensor 184 that detects shake of the camera body 100 and a BIS processing unit 183, which are components that realize a BIS (Body Image Stabilizer) function that corrects shake by moving the image sensor inside the camera body 100. The BIS processing unit 183 controls the shake correction process based on the detection result of the gyro sensor 184. The camera body 100 also includes a sensor driving unit 181 that moves the image sensor 110, and a position sensor 182 that detects the position of the image sensor 110.

The sensor driving unit 181 can be realized, for example, by a magnet and a flat coil. The sensor driving unit 181 may also include other motors or actuators. The position sensor 182 is a sensor that detects the position of the image sensor 110 in a plane perpendicular to the optical axis of the optical system. The position sensor 182 can be realized, for example, by a magnet and a Hall element.

The BIS processing unit 183 controls the sensor driving unit 181 based on the signal from the gyro sensor 184 and the signal from the position sensor 182 to shift the image sensor 110 in a plane perpendicular to the optical axis so as to offset the shake of the camera body 100.

1-2. Interchangeable Lens The interchangeable lens 200 includes an optical system, a lens control unit 240, a RAM 241, a ROM 242, and a lens mount 250. The optical system includes a zoom lens 210, an OIS (Optical Image Stabilizer) lens 220, a focus lens 230, and an aperture 260. The interchangeable lens 200 also includes a zoom drive unit 211, an OIS drive unit 221, a focus drive unit 231, and an aperture drive unit 262 that drive the various elements of the optical system. In the digital camera 1 of this embodiment, the focus drive unit 231, the encoder 232, the lens control unit 240, the RAM 241, and the ROM 242 constitute a drive module 20 for driving the focus lens 230.

The zoom lens 210 is a lens for changing the magnification of a subject image formed by the optical system. The zoom lens 210 is composed of one or more lenses. The zoom lens 210 is driven by a zoom drive unit 211. The zoom drive unit 211 includes a zoom ring that can be operated by the user. Alternatively, the zoom drive unit 211 may include a zoom lever and an actuator or a motor. The zoom drive unit 211 moves the zoom lens 210 along the optical axis direction of the optical system in response to operation by the user.

The focus lens 230 is a lens for changing the focus state of the subject image formed on the image sensor 110 by the optical system. The focus lens 230 is composed of one or more lenses. The focus lens 230 is driven by a focus drive unit 231.

The focus driver 231 includes an actuator or a motor, and moves the focus lens 230 along the optical axis of the optical system under the control of the lens controller 240. In this embodiment, the focus driver 231 is realized by a stepping motor. The interchangeable lens 200 also includes an encoder 232 for detecting the position of the focus lens 230 driven by the focus driver 231.

For example, the encoder 232 is realized by a GMR (giant magnetoresistance) sensor. In this embodiment, the encoder 232 detects the rotation of the motor in the focus drive unit 231 as a rotary encoder and outputs a signal according to the detection result to the lens control unit 240. For example, the encoder 232 detects the rotation position, the amount of rotation, the rotation speed, and/or the rotation direction as the rotation of the motor.

The OIS lens 220 is a lens for correcting blur of a subject image formed by the optical system of the interchangeable lens 200 in the OIS function that corrects blur by moving a correction lens in the interchangeable lens 200. The OIS lens 220 reduces blur of the subject image on the image sensor 110 by moving in a direction that offsets blur of the digital camera 1. The OIS lens 220 is composed of one or more lenses. The OIS lens 220 is driven by an OIS driver 221.

The OIS driving unit 221 shifts the OIS lens 220 in a plane perpendicular to the optical axis of the optical system under the control of the OIS processing unit 223. The OIS driving unit 221 can be realized, for example, by a magnet and a flat coil. The position sensor 222 is a sensor that detects the position of the OIS lens 220 in a plane perpendicular to the optical axis of the optical system. The position sensor 222 can be realized, for example, by a magnet and a Hall element. The OIS processing unit 223 controls the OIS driving unit 221 based on the output of the position sensor 222 and the output of the gyro sensor 224.

The lens control unit 240 controls the operation of the interchangeable lens 200 by controlling the components such as the drive units 211, 221, 231, and 262 in response to a control signal from the camera control unit 140, for example. For example, the lens control unit 240 controls the focus drive unit 231 to drive the focus lens 230 in the autofocus (AF) operation of the digital camera 1.

RAM 241 is a recording medium that functions as a work memory for lens control unit 240. For example, RAM 241 is realized by a DRAM or the like, and temporarily stores various data and information for digital camera 1. ROM 242 is a non-volatile recording medium. For example, ROM 242 is realized by a flash memory or the like, and stores predetermined setting values for digital camera 1. Each of RAM 141, 241 and ROM 142, 242 is an example of a storage unit of digital camera 1 in this embodiment.

The aperture 260 adjusts the amount of light incident on the image sensor 110. The aperture 260 is driven by an aperture drive unit 262, and the size of its opening is controlled. The aperture drive unit 262 includes a motor or actuator.

The gyro sensor 184 or 224 detects shake (vibration) of the digital camera 1 based on the angle change per unit time of the digital camera 1, i.e., the angular velocity. The gyro sensor 184 or 224 outputs an angular velocity signal indicating the amount of shake (angular velocity) detected to the BIS processing unit 183 or OIS processing unit 223. Instead of the gyro sensor, other sensors capable of detecting shake of the digital camera 1 can also be used.

The camera control unit 140 and the lens control unit 240 may be configured as a hardwired electronic circuit, or may be configured as a microcomputer using a program. For example, the camera control unit 140 and the lens control unit 240 can be realized by various processors such as a CPU, MPU, GPU, DSU, FPGA, or ASIC. The camera control unit 140 and the lens control unit 240 are each an example of a control unit in the digital camera 1 of this embodiment.

1-3. Drive module Fig. 2 is a diagram illustrating an example of the configuration of the drive module 20 in the digital camera 1 of this embodiment. In the example of Fig. 2, the focus drive unit 231 of the drive module 20 includes a lead shaft 233, a lead screw 234, a stepping motor 236, and a motor driver 237. Hereinafter, the stepping motor is abbreviated as "STM". In addition, the lens control unit 240 includes, for example, an encoder detection unit 243, a motor control unit 244, and a step-out recovery control unit 245 as functional components.

For example, the lens control unit 240 functions as an encoder detection unit 243, a motor control unit 244, and a step-out recovery control unit 245 by reading and executing a program stored in the ROM 242.

The focus driver 231 rotates the lead screw 234 using the STM 236, and moves the focus lens 230 in the optical axis direction using the lead shaft 233 and the lead screw 234.

The encoder 232 is attached to the lead screw 234, and outputs a signal corresponding to the rotation of the STM 236 to the encoder detector 243. The encoder detector 243 detects the position to which the focus lens 230 moves along the optical axis, for example, by encoding the sine wave signal output from the encoder 232. For example, the encoder 232 can detect the position of the focus lens 230 corresponding to the actual rotation of the STM 236, and the focus lens 230 can be positioned with high accuracy. The encoder 232 and the encoder detector 243 are an example of a position detector in this embodiment.

The STM236 is, for example, a two-phase STM, and includes coils that are excited by supplying a current or voltage for each of phases A and B, and a rotor. For example, each coil of the STM236 is excited by application of a voltage of a drive signal output from the motor driver 237, and the rotor rotates in response to the excitation, thereby driving the STM236.

The motor driver 237 outputs a drive signal to the STM 236 in response to a control signal from the motor control unit 244. In this embodiment, the STM 236 is driven by microstep drive in which the voltage of the drive signal changes to have a sine wave waveform. The motor control unit 244 manages the position of the focus lens 230 driven by the STM 236 in, for example, the RAM 241, and outputs a control signal to the motor driver 237 to rotate the STM 236 in accordance with the managed position.

The out-of-step recovery control unit 245 detects out-of-step of the STM 236 based on, for example, the encoder position detected by the encoder detection unit 243 and the position managed by the motor control unit 244. In this embodiment, out-of-step is detected as a state in which the position detected by the encoder detection unit 243 deviates from the position managed by the motor control unit 244 by more than a predetermined value.

When a step-out is detected, the step-out recovery control unit 245 executes a predetermined process for recovering from the step-out, thereby controlling the motor driver 237 to eliminate the step-out by a control signal from the motor control unit 244. The step-out recovery process will be described in detail later.

The configuration of the drive module 20 is not limited to the above example, and for example, the lens control unit 240 may control the encoder detection unit 243, the motor control unit 244, and the step-out recovery control unit 245, each of which is implemented in a dedicated hardware circuit.

2. Operation The operation of the digital camera 1 configured as above will now be described.

The digital camera 1 of this embodiment performs, for example, an AF operation by driving the focus lens 230 with the drive module 20. For example, the motor control unit 244 of the drive module 20 shown in FIG. 2 manages the target position and current position of the focus lens 230 as the position of the focus lens 230. The target position is determined, for example, by the lens control unit 240 in the AF operation, and is managed as the position to which the focus lens 230 is moved. The current position is managed as the position to which the focus lens 230 is driven, based on the accumulated amount of movement of the focus lens 230 that the motor control unit 244 sequentially instructs the motor driver 237.

Figure 3 is a diagram for explaining the operation of the drive module 20. The drive module 20 drives the focus lens 230 by, for example, applying drive signal voltages from the motor driver 237 to the A-phase coil and the B-phase coil of the STM 236, respectively, and rotating the STM 236 in steps corresponding to a predetermined rotation angle by excitation. Figure 3(A) illustrates the time change of the voltage of each phase of the STM 236. Figure 3(A) also shows the position to which the focus lens 230 is driven corresponding to the step of the STM 236 at each time. In the example of Figure 3(A), the drive module 20 moves the focus lens 230 from position "0" to position "24".

The drive module 20 controls the STM 236 by a drive signal so that the current position Pc of the focus lens 230 coincides with the target position Pt. In the example of FIG. 3(A), in addition to the current position Pc after driving, the encoder position Pe detected using the encoder 232 coincides with the target position Pt. The encoder position Pe is detected by the encoder detection unit 243 as the position of the focus lens 230 in a unit system common to the current position Pc and the target position Pt, based on the detection result of the rotation of the STM 236 from the encoder 232.

For example, as shown in FIG. 3A, after the current position Pc reaches the target position Pt, the drive module 20 maintains the power supply to the STM 236 for a predetermined period after the STM 236 stops in order to hold the stop position of the focus lens 230 when the STM 236 is stopped. In this way, the application of the voltage corresponding to the target position Pt is maintained for a predetermined period.

Figure 3 (B) illustrates the correspondence between the position of the focus lens 230 in the example of Figure 3 (A) and the voltage of the drive signal applied to each coil of the A phase and B phase of the STM 236. Voltage data D1 that specifies the voltage for each position is stored in advance, for example, in the ROM 242. In the voltage data D1 of this example, the same voltage is applied every time the position is separated by "8". Thus, in this example, the period of the sine wave of the voltage, i.e., the period of the drive signal, corresponds to the position difference of "8". The drive module 20 excites the STM 236 using this voltage data D1 in a magnetic field pattern formed in the coils of each phase of the STM 236 so that the same state is achieved for each position corresponding to the period of the drive signal.

Here, while the STM 236 is stopped, the drive signal may not be synchronized with the rotation of the STM 236, resulting in loss of synchronization. For example, loss of synchronization may occur when an external disturbance such as dropping the digital camera 1 or applying vibration to the digital camera 1 causes the STM 236 to rotate and move the focus lens 230 from the stopped position where it was held. For example, if loss of synchronization occurs due to an external disturbance such as a drop while an image is being captured with the digital camera 1, there is a concern that this may affect the focus accuracy of the AF operation.

Figure 3 (B) illustrates the encoder position Pe, current position Pc, and target position Pt when step-out occurs while the STM 236 is stopped after the focus lens 230 has been driven to the target position Pt. When step-out occurs, it is assumed that the encoder position Pe shifts from the target position Pt, which is the stop position of the focus lens 230 before step-out, due to movement of the focus lens 230 caused by disturbances, etc. In the drive module 20 of this embodiment, the step-out recovery control unit 245 detects step-out according to such a shift between the target position Pt and the encoder position Pe. When step-out is detected, the step-out recovery control unit 245 executes step-out recovery processing to recover from step-out based on the target position Pt and the encoder position Pe. Details of the step-out recovery processing will be described later.

According to the driving module 20 of this embodiment, for example, open-loop control is possible without feedback of the encoder position Pe each time the STM 236 is driven, while the encoder position Pe can be used to detect loss of synchronism caused by disturbances or the like while the STM 236 is stopped. When loss of synchronism is detected, the driving module 20 performs loss of synchronism recovery processing according to the target position Pt at the time of stop and the encoder position Pe detected at any time. As a result, for example, when driving the STM 236, loss of synchronism can be detected while avoiding complex processing such as feedback through open-loop control, and the digital camera 1 can be quickly restored from loss of synchronism without having to be restarted to initialize it.

2-1. Detection of Step-Out and Recovery The operation of the drive module 20 of this embodiment regarding detection of step-out and recovery will be described with reference to FIGS.

FIG. 4 is a flowchart illustrating the operation of the drive module 20 in this embodiment. The process shown in the flowchart in FIG. 4 is started, for example, when the digital camera 1 is started, and is repeatedly executed at a predetermined cycle by the lens control unit 240.

The lens control unit 240, for example as the step-out recovery control unit 245, determines whether the STM 236 is stopped based on the detection result by the encoder 232 (S1). If the rotation of the STM 236 is detected by the encoder 232 and the STM 236 is not stopped (NO in S1), the lens control unit 240 repeats the determination in step S1, for example at a predetermined cycle.

If the STM 236 is stopped (YES in S1), the lens control unit 240 judges whether or not out-of-step is detected based on the encoder position Pe and the target position Pt (S2). The lens control unit 240 judges whether or not out-of-step has occurred based on whether or not the difference between the encoder position Pe and the target position Pt is greater than a predetermined out-of-step threshold. The out-of-step threshold is preset as a predetermined value (e.g., "2") that is less than half the position difference ("8" in the example of FIG. 3) corresponding to the period of the drive signal of the STM 236, from the viewpoint of increasing the possibility of recovery from out-of-step due to excitation in step S3 described later, and is stored in the ROM 242, etc. If out-of-step is not detected (NO in S2), the lens control unit 240 returns to, for example, step S1.

If out-of-step is detected (YES in S2), the lens control unit 240 executes out-of-step recovery processing from step S3 onwards. First, the lens control unit 240 outputs a control signal to the motor driver 237 as the motor control unit 244 so as to excite the STM 236 corresponding to the target position Pt when stopped, for example based on the voltage data D1 (S3). With such excitation, the STM 236 rotates so as to be drawn into a rotational position corresponding to the excited position by a magnetic field of the same pattern as the magnetic field pattern that controlled the motor driver 237 when the STM 236 was stopped, and the focus lens 230 is driven.

Figure 5 is a timing chart for explaining the recovery operation from loss of synchronism caused by excitation of the drive module 20 of this embodiment. Figure 5 shows an example of operation during loss of synchronism in the example of Figure 3(B) where the degree of loss of synchronism is relatively small. Figures 5(A), (B), and (C) respectively show whether or not excitation is performed on the STM 236 (i.e., excitation is on or off), the encoder position Pe, and the change over time of the current position Pc. In Figures 5(B) and (C), the target position Pt is shown by a dashed line.

In the example of Figure 5, after excitation is turned off in response to the stop of the STM236, step-out occurs at time t1 as shown in Figure 5 (B), and the encoder position Pe changes from "24", which coincides with the target position Pt at the time of stop, to "21". After that, from time t2, excitation corresponding to the target position Pt is performed (S3).

After turning on the excitation of the target position Pt (S3), the lens control unit 240 waits for a predetermined period (e.g., 100 to 200 milliseconds) (S4). The predetermined period is set in advance according to the drive target of the STM 236 and is stored in the ROM 242 or the like. For example, as shown in FIG. 5(A), the state of excitation according to the target position Pt continues for the predetermined period from time t2 to time t3.

After waiting for a predetermined period of time (S4), the lens control unit 240 determines whether the difference between the encoder position Pe and the target position Pt is greater than the out-of-step threshold, i.e., whether out-of-step is detected, as in step S2 (S5).

In the example of FIG. 5, the focus lens 230 moves toward the target position Pt by retracting the STM 236 in response to the excitation (S3) of the target position Pt. In this case, as shown in FIG. 5(B), for example, the encoder position Pe changes from the position after the step-out and returns to the position before the step-out at time t3, so the step-out is resolved and not detected (NO in S5).

If the difference between the encoder position Pe and the target position Pt is equal to or less than the out-of-step threshold and out-of-step is not detected (NO in S5), the lens control unit 240 does not execute the processes in steps S6 and onwards and ends the process of this flowchart. In this case, as shown in FIG. 5(A), for example, the lens control unit 240 controls the motor driver 237 so as not to excite the STM 236 after time t3, which is a predetermined waiting period. Also, as shown in FIG. 5(C), the current position Pc is not changed from before the out-of-step.

On the other hand, if the difference between the encoder position Pe and the target position Pt is greater than the out-of-step threshold and out-of-step is detected (YES in S5), the lens control unit 240 calculates the return position to be used to return from the out-of-step based on the encoder position Pe and the target position Pt (S6).

Figure 6 is a diagram for explaining the operation during detuning when the drive module 20 of this embodiment does not return to normal due to excitation. In Figure 6, similar to Figure 3 (B), the encoder position Pe, current position Pc, and target position Pt are shown superimposed on a sine wave indicating the voltage of the drive signal in the voltage data D1. Figure 6 (A) shows an example in which the encoder position Pe moves to the position "19" due to detuning after the focus lens 230 is driven to the target position Pt of "24". Figure 6 (B) shows an example in which the encoder position Pe moves from the state of Figure 6 (A) to the position "16" without returning to the target position Pt after waiting for a predetermined period of time (S4) due to excitation according to the target position Pt (S3).

In the example of FIG. 6, when excitation is performed according to the target position Pt of "24", the encoder position Pe moves to a position of "16", which is in phase with the target position Pt in a sine wave and is closer to the post-step loss "19" than the target position Pt. In this case, the step-out is not resolved by exciting the target position Pt, and step-out is detected (YES in S5), so the processing from step S6 onwards is executed.

In step S6, the lens control unit 240 calculates a return position Pr near the encoder position Pe, where the distance from the target position Pt when the STM 236 is stopped is an integer multiple of the period of the drive signal, using the following calculation formula: Sn indicates the number of steps of the STM 236 that corresponds to one period of the drive signal. In the following calculation formula, the decimal points are rounded down for each calculation as an integer calculation.
(Calculation formula)
Pr = Pt + (((Pe - Pt) + Sn / 2) / Sn) * Sn (if Pe > Pt)
Pr = Pt - (((Pt - Pe) + Sn / 2) / Sn) * Sn (when Pe < Pt)

Figure 7 is a timing chart for explaining the recovery operation from step-out depending on the return position of the drive module 20 of this embodiment. Figure 7 shows an example of the operation during step-out in the example of Figure 6, where the degree of step-out is relatively large. Figures 7 (A), (B), and (C), like Figures 5 (A), (B), and (C), respectively show the time changes in excitation on/off, encoder position Pe, and current position Pc. For example, as shown in Figures 7 (A) and (B), step-out occurs at time t1, excitation of the target position Pt is performed at time t2, causing the encoder position Pe to change, and an unresolved step-out is detected at time t3 after waiting for a predetermined period of time.

In the example of FIG. 7, in the calculation formula of step S6, Pt=24, Pe=16, and Sn=8, and since Pe<Pt, the return position Pr is "16" as follows.
Pr = 24 - (((24 - 16) + 8/2)/8) * 8 = 16

The lens control unit 240 updates the current position Pc managed by the motor control unit 244 to the return position Pr calculated in step S6 (S7), for example, so as to overwrite the current position Pc. In the example of FIG. 7, as shown in FIG. 7(C), the current position Pc is updated to the return position Pr at time t3.

Figure 8 is a diagram for explaining the operation of the drive module 20 from the state of Figure 6 (B). Figure 8 shows the encoder position Pe, current position Pc, and target position Pt, similar to Figures 6 (A) and (B). In the state of Figure 8, the current position Pc has been updated from "19" after step-out in Figure 6 (B) to "16", the return position Pr calculated in step S6.

The calculation formula in step S6 calculates the return position Pr as a position around the position where the step-out position is reached, where the sine wave of the voltage of the drive signal has the same phase as the voltage corresponding to the target position Pt. As a result, of the multiple positions where the magnetic field pattern is the same as the magnetic field pattern that controlled the motor driver 237 according to the target position Pt when the STM 236 is stopped, the position closest to the position after the step-out can be calculated as the return position Pr. In this way, the return position Pr that is consistent with the control of the STM 236 by the drive signal can be calculated and used to update the current position Pc managed by the lens control unit 240.

Then, the lens control unit 240 controls the driving of the STM 236 so as to move the current position Pc updated at the return position Pr to the target position Pt (S8). For example, the lens control unit 240 causes the motor driver 237 to output a drive signal that changes the voltage applied to the STM 236 for each position based on the voltage data D1, similar to the driving of the STM 236 before the step-out. In the example of Figures 7 (A) to (C), excitation is performed from time t3 until the focus lens 230 is stopped at the target position Pt by such a drive signal, and the current position Pc is updated and the encoder position Pe changes as the STM 236 is driven. In this example, the excitation is turned off at time t4 after the current position Pc reaches the target position Pt.

After executing drive control of the STM 236 (S8), the lens control unit 240 ends the processing of this flowchart.

According to the above operation of the drive module 20, when step-out is detected (YES in S2) while the STM 236 is stopped (YES in S1), the STM 236 is excited according to the target position Pt at the time of stopping (S3). After waiting for a predetermined period of time (S4), if step-out is no longer detected due to a change in the encoder position Pe during excitation (NO in S5), it is determined that step-out has been resolved and subsequent processing is not executed. On the other hand, if step-out is still detected (YES in S5), a return position Pr whose distance from the target position Pt is an integer multiple of the period of the excitation drive signal is calculated (S6). Then, after updating the current position Pc managed by the lens control unit 240 to the return position Pr (S7), the STM 236 is driven to move the current position Pc to the target position Pt (S8).

After the STM236 loses synchronism, when the target position Pt is excited (S3), the STM236 is pulled in to a position whose distance from the target position Pt is an integer multiple of the period of the drive signal, that is, a position in phase with the target position Pt in the sine wave of the drive signal voltage. According to the drive module 20 described above, even if the loss of synchronism is not resolved by exciting the target position Pt (YES in S5), as in the examples of Figures 6 and 7, a position in phase closer to the position where the step-out occurred than the target position Pt can be calculated as the return position Pr (S6). The return position Pr is set as the current position Pc, and the STM236 is driven to move to the target position Pt (S7, S8), so that the actual encoder position Pe matches the current position Pc and the target position Pt for management purposes, allowing for accurate recovery from the loss of synchronism.

In addition, in this embodiment, by driving the STM236 to the target position Pt before the step-out (S8), in addition to resolving the step-out, it is possible to return to the position before the step-out.

3. Summary As described above, the driving module 20 of this embodiment drives the focus lens 230 as an example of an element in the digital camera 1 (an example of an imaging device). The driving module 20 includes an STM 236 (an example of a motor) that drives the focus lens 230, a motor driver 237 (an example of a motor driving unit) that controls the excitation of the STM 236, an encoder 232 and an encoder detection unit 243 (an example of a position detection unit) that detect the position of the focus lens 230, and a lens control unit 240 (an example of a control unit) that controls the motor driver 237 and manages the position of the focus lens 230. The lens control unit 240 detects out-of-step when the difference between the encoder position Pe detected by the position detection unit for the focus lens 230 and the target position Pt managed by the lens control unit 240 is greater than an out-of-step threshold (an example of a predetermined value) while driving by the STM 236 is stopped (S2). When a step-out is detected (YES in S2), the lens control unit 240 controls the motor driver 237 to eliminate the step-out by using a magnetic field having the same pattern as the magnetic field pattern controlled when the STM 236 was stopped (S3 to S8).

When the drive module 20 described above detects a step-out while the STM 236 is stopped (YES in S2), control is performed to eliminate the step-out using a magnetic field with the same pattern as the magnetic field pattern that controlled the motor driver 237 when the STM 236 was stopped (S3 to S8). This allows for accurate recovery from the step-out, even if the step-out occurs due to, for example, an external disturbance.

In this embodiment, when step-out is detected (YES in S2), the lens control unit 240 causes the motor driver 237 to excite the STM 236 according to the target position Pt (an example of a stop position) that is managed as the position where the focus lens 230 will stop when the STM 236 is stopped (S3). As a result, in the case of a relatively small degree of step-out such as the examples in Figures 3(B) and 5, the STM 236 can be pulled in according to the excitation to return to the target position Pt at the time of stopping before the step-out.

In this embodiment, the motor driver 237 controls the excitation of the STM 236 by a drive signal for driving the STM 236. When the difference between the encoder position Pe (an example of a detected position) detected by the position detection unit during excitation of the STM 236 according to the target position Pt at the time of stopping (S3 to S4) and the target position Pt is greater than the out-of-step threshold (YES in S5), the lens control unit 240 controls the motor driver 237 to drive the focus lens 230 from the return position Pr, which is an example of a position closest to the encoder position Pe among multiple positions whose distance from the target position Pt is an integer multiple of the period of the drive signal, to the target position Pt (S6 to S8). In this way, by driving from the return position Pr that matches the period of the drive signal to the target position Pt, the out-of-step can be accurately eliminated and the position before the out-of-step can be returned to. As a result, even if the out-of-step is relatively large as in the examples of Figures 6 and 7 and the excitation of the target position Pt (S2) does not return the lens, the lens can accurately return from the out-of-step.

In this embodiment, the position detection unit includes an encoder 232 that detects a position according to the rotation of the STM 236. The encoder 232 can detect, for example, the rotation of the STM 236.

In this embodiment, a digital camera 1, which is an example of an imaging device, includes a drive module 20, an image sensor 110 (an example of an imaging section) that captures a subject image formed via an optical system, and a focus lens 230 (an example of an element) in the optical system that is driven by the drive module 20.

In this embodiment, the interchangeable lens 200 that can be attached to the camera body 100 of the digital camera 1 includes a drive module 20 and an optical system that includes a focus lens 230 that is driven by the drive module 20.

The digital camera 1 and interchangeable lens 200 described above allow the STM 236 to recover from loss of synchronization with high precision by the operation of the drive module 20.

(Embodiment 2)
A second embodiment of the present disclosure will be described below with reference to Figures 9 and 10. In the first embodiment, the drive module 20 of the digital camera 1 drives the STM 236 to the target position Pt before the step-out when recovering from the step-out. In the second embodiment, a digital camera 1 in which the drive module 20 resolves the step-out without performing such driving will be described.

Hereinafter, the description of the configuration and operation similar to those of the digital camera 1 according to the first embodiment will be omitted as appropriate, and the digital camera 1 according to this embodiment will be described.

Figure 9 is a flow chart illustrating the operation of the drive module 20 in embodiment 2. In the same operation as in embodiment 1, the drive module 20 in this embodiment updates the current position Pc and the target position Pt with the calculated return position Pr (S7 in Figure 4) instead of updating the current position Pc with the calculated return position Pr (S7A), and then does not perform drive control of the STM 236 (S8 in Figure 4).

Figure 10 is a timing chart for explaining the operation of the drive module 20 of the second embodiment. Figures 10(A), (B), (C), and (D) respectively show the excitation to the STM 236, the encoder position Pe, the current position Pc, and the target position Pt over time during a step-out similar to the examples of Figures 6 and 7.

For example, as in the first embodiment, the difference between the encoder position Pe and the target position Pt shown in each of FIGS. 10B and 10D is greater than the out-of-step threshold, and an unresolved out-of-step is detected at time t3 (YES in S5), and the return position Pr is calculated (S6). In this embodiment, the lens control unit 240 updates the current position Pc in FIG. 10C, as well as the target position Pt in FIG. 10D, to the calculated return position Pr (S7A). Thereafter, the lens control unit 240 ends the process of the flowchart in FIG. 9. In this embodiment, since the STM 236 is not driven to the target position Pt, the lens control unit 240 turns off the excitation as shown in FIG. 10A after updating with the return position Pr at time t3 (S7A).

The above operation of the drive module 20 also makes it possible to match the encoder position Pe according to the actual rotation of the STM 236 with the current position Pc and target position Pt managed by the lens control unit 240, and to recover from step-out with high accuracy. In this way, even if the positions differ from those before step-out, the discrepancy between the encoder position Pe and the managed current position Pc and target position Pt is eliminated, and the STM 236, for example, can operate normally from the next drive.

As described above, in the drive module 20 of this embodiment, the motor driver 237 (an example of a motor drive unit) controls the excitation of the STM 236 by a drive signal for driving the STM 236 (an example of a motor). When the difference between the encoder position Pe (an example of a detected position) detected by the encoder 232 and the encoder detector 243 (an example of a position detector) and the target position Pt is greater than the step-out threshold (an example of a predetermined value) (YES in S5) during excitation of the STM 236 according to the target position Pt (an example of a stop position) when the STM 236 is stopped (S3, S4), the lens controller 240 (an example of a controller) calculates the return position Pr as an example of the position closest to the encoder position Pe among a plurality of positions whose distance from the target position Pt is an integer multiple of the period of the drive signal based on the encoder position Pe and the target position Pt (S6). The lens control unit 240 updates the target position Pt and the current position Pc, which is managed according to the drive amount of the focus lens 230 (an example of an element), to the calculated return position Pr (S7A).

According to the drive module 20 described above, if the step-out is not resolved by exciting the STM 236 according to the target position Pt (YES in S5), both the target position Pt and the current position Pc managed by the lens control unit 240 are updated with the return position Pr (S7A). This allows the current position Pc and the target position Pt to be aligned with the return position Pr that is consistent with the period of the drive signal, thereby accurately resolving the step-out, even when the STM 236 is not driven.

(Embodiment 3)
Hereinafter, a third embodiment of the present disclosure will be described with reference to Fig. 11 and Fig. 12. In the first and second embodiments, in the digital camera 1, the drive module 20 detects and restores step-out based on the detection result from the encoder 232 that detects the rotation of the STM 236. In the third embodiment, a digital camera 1 will be described that uses an encoder that detects the linear movement of an object to be driven by the STM 236, such as the focus 230.

Below, we will explain the digital camera 1 according to this embodiment, omitting explanations of the configuration and operation similar to those of the digital camera 1 according to embodiments 1 and 2 as appropriate.

Figure 11 is a diagram illustrating the configuration of the drive module 20A in embodiment 3. Instead of the encoder 232 (see Figure 2) of embodiments 1 and 2 that detects the rotation of the STM 236, the drive module 20A in this embodiment includes an encoder 238 and a magnet 235 for detecting the position to which the focus lens 230 moves in a straight line. The encoder 238 is realized by, for example, a GMR sensor, and as a linear encoder, outputs a signal corresponding to the linear displacement of the focus lens 230 along the lead shaft 233 to the lens control unit 240.

The encoder detector 243 detects the position of the focus lens 230 based on the signal from the encoder 238 as a position in a unit system common to the current position Pc and the target position Pt, for example, as in the first embodiment.

In the driving module 20A of this embodiment, the lens control unit 240 includes, for example, an encoder correction unit 246 as a functional configuration in addition to the same configuration as in the first and second embodiments. For example, it is considered that the position at which the STM 236 rotates and the encoder position detected by the encoder 238 as the position at which the focus lens 230 moves straight ahead do not completely correspond due to individual differences in the encoder 238, etc. The encoder correction unit 246 corrects the encoder position so as to reduce the deviation between the encoder position and the current position Pc and the target position Pt managed by the motor control unit 244. The encoder 238, the encoder detection unit 243, and the encoder correction unit 246 are examples of a position detection unit in the driving module 20A of this embodiment.

12 is a diagram for explaining the encoder correction position in the drive module 20A of the third embodiment. The encoder correction position indicates the encoder position corrected by the encoder correction unit 246. For example, at each rotation position corresponding to the step of the STM 236, the encoder position for each target position Pt is actually measured, and a coefficient α that satisfies the following relational expression is calculated in advance. The encoder position can be corrected by multiplying the detected encoder position by the coefficient α calculated in this manner.
(Relational expression)
Encoder correction position = Encoder position * α

In the driving module 20A of this embodiment, the lens control unit 240 uses the encoder correction position calculated from the detection result of the encoder 238 in place of the encoder position Pe in steps S2, S5, and S6 of FIG. 3 in the same operation as in the first embodiment. The lens control unit 240 of the driving module 20A may use the encoder correction position in place of the encoder position Pe in steps S2, S5, and S6 of FIG. 9 in the same operation as in the second embodiment.

Figure 12 shows the relationship between the encoder position and the encoder correction position for each target position Pt when the coefficient α is "0.91". Due to the influence of cogging of the STM236, etc., it is considered that the target position Pt and the encoder correction position do not completely match. Even in this case, for example, by setting the coefficient α so that the difference between the target position Pt and the encoder correction position is sufficiently smaller than half the period of the drive signal, the return position Pr can be calculated with high accuracy using the encoder correction position, as in the first and second embodiments.

The return position Pr, which is calculated according to the period of the drive signal, can accurately return from step-out even when an error occurs in the encoder position, such as a deviation from the rotational position of the STM236. For example, even if recovery from step-out is repeated multiple times, accumulation of errors can be avoided.

The above describes an example in which a coefficient is used to correct the encoder position, but the correction may also be performed by referencing a lookup table generated from the actually measured encoder position, etc., as described above.

As described above, the position detection unit in the drive module 20A of this embodiment includes the encoder 238 that detects linear displacement of the focus lens 230 (an example of an element). The position detection unit, for example, as the encoder detection unit 243 and the encoder correction unit 246, corrects the detection result by the encoder 238 in accordance with the rotation of the STM 236 (an example of a motor) to detect the position of the focus lens 230. As a result, even the drive module 20A that uses the encoder 238 that detects linear displacement can accurately recover from step-out using the corrected encoder correction position.

Other Embodiments
As described above, the first to third embodiments have been described as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited to these, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made as appropriate. It is also possible to combine the components described in the first to third embodiments to create new embodiments. Therefore, other embodiments will be described below as examples.

In each of the above embodiments, an example has been described in which the STM236 stops, and then the excitation corresponding to the target position Pt is turned off, and then the step-out occurs. The drive module of the present disclosure is not limited to the above example of step-out, and can also be applied to cases in which step-out occurs due to a relatively large disturbance or the like during excitation after stopping. In this case, by continuing the excitation after stopping as excitation for the target position Pt (S3), recovery from step-out can be performed by the same operation as in each of the above embodiments.

In each of the above embodiments, an example has been described in which the digital camera 1 drives the focus lens 230 in an AF operation. In this embodiment, the focus lens 230 may be driven by the drive module 20, 20A not only in an AF operation but also in a manual focus operation.

In the above embodiments, the driving modules 20 and 20A drive the focus lens 230. The driving module of this embodiment may drive various elements in the digital camera 1 instead of or in addition to the focus lens 230. For example, the driving module may be implemented as any one of the zoom driving unit 211, the OIS driving unit 221, and the aperture driving unit 262, which drive the zoom lens 210, the OIS lens 220, and the aperture 260, respectively. The encoder 232 of this embodiment may be arranged to detect the rotation of the motors in the driving units 211, 221, and 262 in the interchangeable lens 200. A linear encoder 238 similar to that of the third embodiment may be arranged to detect the movement of the lens 210, the OIS lens 220, the aperture 260, or the like.

In each of the above embodiments, the lens control unit 240 controlled the driving modules 20 and 20A. In this embodiment, a dedicated microcomputer or the like provided in the digital camera 1, separate from the lens control unit 240, may control the driving modules 20 and 20A.

In each of the above embodiments, the driving module 20, 20A drives elements such as the focus lens 230 in the interchangeable lens 200 by the lens control unit 240. In this embodiment, the camera control unit 140 may also constitute the driving module. In this case, the camera control unit 140 can also communicate with each element in the interchangeable lens 200 via, for example, the body mount 150 and the lens mount 250 to perform operations similar to those of the above embodiments. In the driving module of this embodiment, the camera control unit 140 may also drive elements in the camera body 100. For example, the driving module may be configured as a sensor driving unit 181 that drives the image sensor 110 in the BIS function of the camera body 100.

In each of the above embodiments, the digital camera 1, which is an example of an imaging device, includes a drive module, an image sensor 110 (an example of an imaging section) that captures a subject image formed via an optical system, and elements in at least one of the optical system and the image sensor 110 that are driven by the drive module. With such a digital camera, the operation of the drive module allows the motors that drive the elements to recover from loss of synchronization with high precision.

In each of the above embodiments, a digital camera with interchangeable lenses has been described as an example of an imaging device, but the imaging device of this embodiment may also be a digital camera that is not particularly an interchangeable lens type. Furthermore, the concept of the present disclosure is applicable not only to digital cameras, but also to movie cameras, and to electronic devices with various imaging functions such as camera-equipped mobile phones, smartphones, or PCs.

As described above, the embodiment has been described as an example of the technology disclosed herein. For this purpose, the attached drawings and detailed description have been provided.

Therefore, among the components described in the attached drawings and detailed description, not only are there components essential for solving the problem, but there may also be components that are not essential for solving the problem in order to illustrate the above technology. Therefore, just because those non-essential components are described in the attached drawings or detailed description, it should not be immediately determined that those non-essential components are essential.

In addition, the above-described embodiments are intended to illustrate the technology disclosed herein, and various modifications, substitutions, additions, omissions, etc. may be made within the scope of the claims or their equivalents.

(Summary of aspects)
Various aspects of the present disclosure are listed below.

A first aspect of the present disclosure is a drive module for driving an element in an imaging device. The drive module includes a motor that drives the element, a motor drive unit that controls excitation of the motor, a position detection unit that detects the position of the element, and a control unit that controls the motor drive unit to manage the position of the element. The control unit detects out-of-step when the difference between the position of the element detected by the position detection unit and the position of the element managed by the control unit is greater than a predetermined value while driving by the motor is stopped. When out-of-step is detected, the control unit controls the motor drive unit to eliminate the out-of-step by using a magnetic field having the same pattern as the magnetic field pattern controlled when the motor was stopped.

In the second aspect, in the drive module of the first aspect, when a loss of synchronism is detected, the control unit causes the motor drive unit to excite the motor according to the stop position that is managed as the position where the element stops when the motor is stopped.

In a third aspect, in the drive module of the second aspect, the motor drive unit controls the excitation of the motor by a drive signal for driving the motor. When the difference between the detection position detected by the position detection unit during excitation of the motor according to the stop position and the stop position is greater than a predetermined value, the control unit controls the motor drive unit to drive the element from the position closest to the detection position among multiple positions whose distance from the stop position is an integer multiple of the period of the drive signal to the stop position.

In a fourth aspect, in the drive module of the second aspect, the motor drive unit controls the excitation of the motor by a drive signal for driving the motor. When the difference between the detection position detected by the position detection unit during excitation of the motor according to the stop position and the stop position is greater than a predetermined value, the control unit calculates, based on the detection position and the stop position, the position closest to the detection position among multiple positions whose distance from the stop position is an integer multiple of the period of the drive signal. The control unit updates the stop position and the position managed according to the drive amount of the element to the calculated position.

In a fifth aspect, in the drive module of any one of the first to fourth aspects, the position detection unit includes an encoder that detects a position according to the rotation of the motor.

In a sixth aspect, in the drive module of any one of the first to fourth aspects, the position detection unit includes an encoder that detects the linear displacement of the element, and detects the position of the element by correcting the detection result by the encoder in accordance with the rotation of the motor.

The seventh aspect is an imaging device that includes a drive module according to any one of the first to sixth aspects, an imaging section that captures a subject image formed via an optical system, and an element in at least one of the optical system and the imaging section that is driven by the drive module.

The eighth aspect is an interchangeable lens that can be attached to a camera body in an imaging device, and includes a drive module according to any one of the first to sixth aspects, and an optical system that includes an element driven by the drive module.

The concept of the present disclosure can be applied to a drive module for driving elements in an imaging device with a motor, as well as to an imaging device equipped with a drive module and an interchangeable lens that constitutes an imaging device.

1 Digital camera 100 Camera body 110 Image sensor 140 Camera control unit 141 RAM
142 ROM
181 Sensor driving unit 200 Interchangeable lens 210 Zoom lens 211 Zoom driving unit 220 OIS lens 221 OIS driving unit 230 Focus lens 231 Focus driving unit 232, 238 Encoder 237 Motor driver 240 Lens control unit 241 RAM
242 ROM
260 Aperture 262 Aperture drive unit

Claims (8)

1. A driving module for driving an element in an imaging device, comprising:
A motor for driving the element;
a motor drive unit that controls excitation of the motor by a drive signal for driving the motor ;
A position detection unit that detects the position of the element;
a control unit that controls the motor drive unit and manages the position of the element;
The control unit is
detecting a step-out in which a difference between a position of the element detected by the position detection unit and a position of the element managed by the control unit is greater than a predetermined value while the drive by the motor is stopped;
When the step-out is detected, the motor drive unit excites the motor in accordance with a stop position managed as a position where the element stops when the motor is stopped;
When a difference between a detection position detected by the position detection unit during excitation of the motor according to the stop position and the stop position is greater than the predetermined value,
The motor drive unit is controlled so as to drive the element from a position closest to the detection position among a plurality of positions whose distance from the stop position is an integer multiple of the period of the drive signal to the stop position.
Drive module. 1. A driving module for driving an element in an imaging device, comprising:
A motor for driving the element;
a motor drive unit that controls excitation of the motor by a drive signal for driving the motor;
A position detection unit that detects the position of the element;
a control unit that controls the motor drive unit and manages the position of the element;
The control unit is
detecting a step-out in which a difference between a position of the element detected by the position detection unit and a position of the element managed by the control unit is greater than a predetermined value while the drive by the motor is stopped;
When the step-out is detected, the motor drive unit excites the motor in accordance with a stop position managed as a position where the element stops when the motor is stopped;
When a difference between the detected position detected by the position detection unit during excitation of the motor according to the stop position and the stop position is greater than the predetermined value,
calculating a position closest to the detection position among a plurality of positions whose distance from the stop position is an integer multiple of a period of the drive signal, based on the detection position and the stop position;
The stop position and the position managed according to the driving amount of the element are updated to the calculated position.
Drive module. The drive module according to claim 1 , wherein the position detection unit includes an encoder that detects a position according to rotation of the motor. The drive module according to claim 1 , wherein the position detection section includes an encoder that detects a linear displacement of the element, and detects the position of the element by correcting a detection result by the encoder in accordance with rotation of the motor. The position detection unit includes an encoder that detects a position according to the rotation of the motor.
A drive module according to claim 2. The position detection unit includes an encoder that detects a linear displacement of the element, and detects the position of the element by correcting a detection result by the encoder in accordance with the rotation of the motor.
A drive module according to claim 2. A drive module according to any one of claims 1 to 6,
an imaging unit that captures a subject image formed via an optical system;
An imaging device comprising an element driven by the drive module in at least one of the optical system and the imaging section. An interchangeable lens that can be attached to a camera body of an imaging device,
A drive module according to any one of claims 1 to 6,
and an optical system including an element driven by the drive module.

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