Drive module, imaging apparatus, and interchangeable lens

Abstract

To provide a drive module or the like which can be accurately returned from the step-out of a motor.SOLUTION: The drive module for driving an element in an imaging apparatus includes: the motor for driving an element; a motor driving part for controlling the excitation of the motor; a position detection part for detecting the position of the element; and a control part for controlling the motor driving part, to manage the position of the element. The control part detects the step-out in which a difference between a position of the element detected by the position detection part and a position of the element managed by the control part is larger than a predetermined value, during the stop of the driving performed by the motor. When the step-out is detected, the control part controls the motor driving part so as to eliminate the step-out by using a magnetic field having the same pattern as the pattern of the magnetic field controlled when the motor is stopped.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a drive module for driving elements in an imaging device, an imaging device including the drive module, and an interchangeable lens.

Background Art

[0002] Patent Document 1 discloses a sewing machine that aims to perform control to prevent out-of-tune of a pulse motor by detecting the movement amount of a driven part even in a drive stop state of the pulse motor. The sewing machine of Patent Document 1 makes the target position of the driven part approach the current position so that the difference between the target position and the current position based on the detected movement amount is equal to or less than an out-of-tune limit value, that is, so as not to be out of tune. Thereafter, the sewing machine sets the target position to the stop position where the pulse motor stopped at the end of driving, and controls the pulse motor so that the current position returns to the stop position. By performing such feedback control of the pulse motor, prevention of out-of-tune is achieved even when there is a possibility of out-of-tune due to an external force being applied.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a drive module, an imaging device, and an interchangeable lens that can accurately return from out-of-tune of a motor.

Means for Solving the Problems

[0005] A drive module according to an 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 a demodulation in which 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 the drive by the motor is stopped. When demodulation is detected, the control unit controls the motor drive unit to eliminate the demodulation using a magnetic field pattern identical to the magnetic field pattern controlled at the time of stopping the motor.

[0006] An imaging device according to an aspect of the present disclosure includes the drive module of the present disclosure, an imaging unit that images a subject image formed through an optical system, and an element driven by the drive module in at least one of the optical system and the imaging unit.

[0007] An interchangeable lens according to an aspect of the present disclosure is an interchangeable lens attachable to a camera body in an imaging device, and includes the drive module of the present disclosure and an optical system including an element driven by the drive module.

Advantages of the Invention

[0008] According to the drive module, imaging device, and interchangeable lens of the present disclosure, it is possible to accurately recover from motor demodulation.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

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Figure 12

Best Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments in the present disclosure will be described with appropriate reference to the drawings. However, in the detailed description, unnecessary parts of the description regarding the prior art and substantially the same configurations may be omitted. This is for the purpose of simplifying the explanation. Also, the following description and the accompanying drawings are disclosed so that those skilled in the art can fully understand the present disclosure, and are not intended to limit the subject matter of the claims.

[0011] (Embodiment 1) In Embodiment 1, a digital camera will be described as an example of an imaging device including the drive module of the present disclosure.

[0012] 1. Configuration Fig. 1 is a block diagram showing the configuration of a digital camera 1 according to Embodiment 1. The digital camera 1 is composed of a camera body 100 and an interchangeable lens 200 that is detachable therefrom.

[0013] 1-1. Camera body The camera body 100 includes 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.

[0014] 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 an instruction 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 work memory during control operations and image processing operations.

[0015] The image sensor 110 is an example of an imaging device that captures a subject image incident via an 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 predetermined image processing by the camera control unit 140. The predetermined image processing is, for example, gamma correction processing, white balance correction processing, defect correction processing, YC conversion processing, electronic zoom processing, and / or JPEG compression processing.

[0016] The image sensor 110 operates at a timing controlled by the timing generator 112. The image sensor generates a still image or a moving image for recording or a through image. The through image is mainly a moving image and is displayed on the liquid crystal monitor 120 for the user to determine the composition for capturing a still image.

[0017] The liquid crystal monitor 120 displays images such as through images and various information such as menu screens. The liquid crystal monitor 120 is an example of the display unit in the present embodiment. Instead of the liquid crystal monitor, other types of display devices, for example, organic EL display devices, may be used.

[0018] The operation unit 130 includes various operation members such as a release button for instructing the start of shooting, a mode dial for setting the shooting mode, and a power switch. The operation unit 130 also includes a touch panel arranged to overlap the liquid crystal monitor 120.

[0019] The RAM 141 is a recording medium that functions as a work memory of the camera control unit 140. The RAM 141 is realized by a DRAM (Dynamic Random Access Memory) or the like. The RAM 141 temporarily stores (i.e., holds) image data generated by, for example, the image sensor 110 and various setting information in the digital camera 1. The ROM 142 is a non-volatile recording medium. The ROM 142 is realized by a flash memory or the like. For example, the ROM 142 stores predetermined set values in the digital camera 1.

[0020] The card slot 170 can accommodate the memory card 171 and controls the memory card 171 based on control from the camera control unit 140. The digital camera 1 can store image data in the memory card 171 or read out image data from the memory card 171.

[0021] The shutter 180 adjusts the exposure time (exposure period) 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.

[0022] 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 the exposure synchronization signal received from the camera control unit 140 to the lens control unit 240 via the lens mount 250. Also, 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. Further, the body mount 150 transmits the signal received from the lens control unit 240 via the lens mount 250 to the camera control unit 140.

[0023] In addition, the camera body 100 includes a gyro sensor 184 that detects shake of the camera body 100 and a BIS (Body Image Stabilizer) processing unit 183 as a configuration that realizes a BIS function of moving the imaging element in the camera body 100 to correct shake. The BIS processing unit 183 controls shake correction processing based on the detection result of the gyro sensor 184. Further, the camera body 100 includes a sensor drive unit 181 that moves the image sensor 110 and a position sensor 182 that detects the position of the image sensor 110.

[0024] The sensor drive unit 181 can be realized by, for example, a magnet and a flat coil. The sensor drive unit 181 may include other motors or actuators, etc. 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 by, for example, a magnet and a Hall element.

[0025] Based on the signal from the gyro sensor 184 and the signal from the position sensor 182, the BIS processing unit 183 controls the sensor drive unit 181 to shift the image sensor 110 in a plane perpendicular to the optical axis so as to cancel out the shake of the camera body 100.

[0026] 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 a diaphragm 260. Also, the interchangeable lens 200 includes a zoom drive unit 211, an OIS drive unit 221, a focus drive unit 231, and a diaphragm drive unit 262 for driving each element of the optical system. In the digital camera 1 of the present 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.

[0027] The zoom lens 210 is a lens for changing the magnification of the 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 operable 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 an operation by the user.

[0028] 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.

[0029] The focus drive unit 231 includes an actuator or a motor and moves the focus lens 230 along the optical axis of the optical system based on the control of the lens control unit 240. The focus drive unit 231 of the present embodiment is realized by a stepping motor. Also, the interchangeable lens 200 includes an encoder 232 for detecting the position of the focus lens 230 driven by the focus drive unit 231.

[0030] For example, the encoder 232 is realized by a GMR (giant magnetoresistance) sensor. The encoder 232 of the present embodiment detects the rotation of the motor in the focus driving 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, rotation amount, rotation speed, and / or rotation direction of the motor as the rotation of the motor.

[0031] The OIS lens 220 is a lens for correcting the blur of the subject image formed by the optical system of the interchangeable lens 200 in the OIS function of moving the correction lens in the interchangeable lens 200 to correct the blur. The OIS lens 220 moves in a direction that cancels out the blur of the digital camera 1, thereby reducing the blur of the subject image on the image sensor 110. The OIS lens 220 is composed of one or more lenses. The OIS lens 220 is driven by the OIS driving unit 221.

[0032] The OIS driving unit 221 receives the control from the OIS processing unit 223 and shifts the OIS lens 220 in a plane perpendicular to the optical axis of the optical system. The OIS driving unit 221 can be realized by, for example, 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 by, for example, 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.

[0033] The lens control unit 240 controls the operation of the interchangeable lens 200 by controlling components such as the driving units 211, 221, 231, 262, etc. according to, for example, a control signal from the camera control unit 140. For example, in the auto focus (AF) operation of the digital camera 1, the lens control unit 240 controls the focus driving unit 231 to drive the focus lens 230.

[0034] RAM 241 is a recording medium that functions as a work memory of the lens control unit 240. For example, RAM 241 is realized by a DRAM or the like and temporarily stores various data and information in the 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 in the digital camera 1. Each of RAMs 141 and 241 and ROMs 142 and 242 is an example of a storage unit of the digital camera 1 in the present embodiment.

[0035] 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 aperture is controlled. The aperture drive unit 262 includes a motor or an actuator.

[0036] The gyro sensor 184 or 224 detects shake (vibration) of the digital camera 1 based on the angular change per unit time of the digital camera 1, that is, the angular velocity. The gyro sensor 184 or 224 outputs an angular velocity signal indicating the detected amount of shake (angular velocity) to the BIS processing unit 183 or the OIS processing unit 223. Instead of the gyro sensor, other sensors capable of detecting shake of the digital camera 1 can also be used.

[0037] The camera control unit 140 and the lens control unit 240 may be configured by hard-wired electronic circuits or may be configured by a microcomputer using a program or the like. 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 the present embodiment.

[0038] 1-3. Drive Module FIG. 2 is a diagram illustrating the configuration of the drive module 20 in the digital camera 1 of the present 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". Further, the lens control unit 240 includes, for example, an encoder detection unit 243, a motor control unit 244, and an out-of-tune return control unit 245 as functional configurations.

[0039] For example, the lens control unit 240 functions as the encoder detection unit 243, the motor control unit 244, and the out-of-tune return control unit 245 by reading and executing a program stored in the ROM 242.

[0040] The focus drive unit 231 rotates the lead screw 234 by the STM 236, and moves the focus lens 230 in the optical axis direction by the lead shaft 233 and the lead screw 234.

[0041] 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 detection unit 243. The encoder detection unit 243 detects the position where the focus lens 230 moves along the optical axis, for example, by encoding the sine wave signal output from the encoder 232. According to the encoder 232, for example, the position of the focus lens 230 corresponding to the actual rotation of the STM 236 can be detected, and the focus lens 230 can be accurately positioned. The encoder 232 and the encoder detection unit 243 are an example of the position detection unit in the present embodiment.

[0042] The STM 236 is, for example, a two-phase STM, and includes a coil excited by supplying current or voltage to each of the A phase and the B phase, and a rotor. For example, each coil of the STM 236 is excited by applying the voltage of the drive signal output from the motor driver 237, and the STM 236 is driven by the rotation of the rotor in response to the excitation.

[0043] The motor driver 237 outputs a drive signal to the STM236 in response to a control signal from the motor control unit 244. In this embodiment, the STM236 is driven by microstep drive in which the voltage of the drive signal changes so as to have a sine wave waveform. The motor control unit 244 manages, for example, in the RAM 241 or the like, the position of the focus lens 230 driven by the STM236, and outputs to the motor driver 237 a control signal for rotating the STM236 according to the managed position.

[0044] The out-of-tune recovery control unit 245 detects the out-of-tune of the STM236 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, the out-of-tune is detected as a state in which the position detected by the encoder detection unit 243 deviates by more than a predetermined value in comparison with the position managed by the motor control unit 244.

[0045] When out-of-tune is detected, the out-of-tune recovery control unit 245 controls the motor driver 237 so as to eliminate the out-of-tune by a control signal from the motor control unit 244 by executing a predetermined process for recovering from the out-of-tune. Details of such out-of-tune recovery processing will be described later.

[0046] The configuration of the drive module 20 is not limited to the above example. For example, the lens control unit 240 may control the encoder detection unit 243, the motor control unit 244, and the out-of-tune recovery control unit 245, each of which is implemented in a dedicated hardware circuit.

[0047] 2. Operation The operation of the digital camera 1 configured as described above will be described below.

[0048] The digital camera 1 of the present embodiment performs, for example, an AF operation by driving the focus lens 230 by 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 the current position of the focus lens 230 as the position of the focus lens 230. The target position is managed as the position at which the lens control unit 240 determines and moves the focus lens 230 in, for example, an AF operation. The current position is managed as the position where the focus lens 230 is driven by, for example, the cumulative amount of movement of the focus lens 230 that the motor control unit 244 sequentially instructs the motor driver 237.

[0049] FIG. 3 is a diagram for explaining the operation of the drive module 20. The drive module 20 drives the focus lens 230 by applying voltages of drive signals from the motor driver 237 to the A-phase coil and the B-phase coil of the STM236, respectively, and rotating the STM236 step by step according to a predetermined rotation angle by excitation. FIG. 3(A) illustrates the time change of the voltage of each phase of the STM236. FIG. 3(A) further shows the position where the focus lens 230 is driven corresponding to the step of the STM236 at each time. In the example of FIG. 3(A), the drive module 20 moves the focus lens 230 from the position "0" to the position "24".

[0050] The drive module 20 controls the STM236 with 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 based on the detection result of the rotation of the STM236 from the encoder 232 as the position of the focus lens 230 in a unit system common to the current position Pc and the target position Pt.

[0051] For example, as shown in FIG. 3(A), when the driving module 20 stops the STM236 after the current position Pc reaches the target position Pt, in order to hold the stop position of the focus lens 230, power is supplied to the STM236 for a predetermined period after the stop of the STM236. In this way, the application of the voltage corresponding to the target position Pt is maintained for a predetermined period.

[0052] FIG. 3(B) illustrates the correspondence between the position of the focus lens 230 in the example of FIG. 3(A) and the voltage of the drive signal applied to each coil of the A-phase and B-phase of the STM236. The voltage data D1 that defines the voltage for each such position is stored in advance in, for example, the ROM 242. In the voltage data D1 of this example, a voltage of the same magnitude is applied every time the position is "8" apart. In this way, in this example, the period of the sine wave of the voltage, that is, the period of the drive signal, corresponds to the position difference "8". The driving module 20 excites the STM236 in the pattern of the magnetic field formed in each phase coil of the STM236 so as to be in the same state for each position corresponding to the period of the drive signal according to such voltage data D1.

[0053] Here, during the stop of the STM236, synchronization between the drive signal and the rotation of the STM236 may not be achieved, resulting in detuning. For example, detuning may occur due to the rotation of the STM236 caused by an external disturbance such as the dropping of the digital camera 1 or vibration applied to the digital camera 1, which causes the focus lens 230 to move from the held stop position. For example, if detuning occurs due to an external disturbance such as dropping during image shooting with the digital camera 1, there is concern that it will affect the focus accuracy of the AF operation.

[0054] FIG. 3(B) illustrates the encoder position Pe, the current position Pc, and the target position Pt when out-of-tune occurs during the stop of the STM236 after driving the focus lens 230 to the target position Pt. When out-of-tune occurs, it is assumed that the encoder position Pe shifts due to the movement of the focus lens 230 caused by external disturbances or the like from the target position Pt, which is the stop position of the focus lens 230 before out-of-tune. The drive module 20 of the present embodiment detects out-of-tune according to the shift between the target position Pt and the encoder position Pe by the out-of-tune recovery control unit 245. When out-of-tune is detected, the out-of-tune recovery control unit 245 executes an out-of-tune recovery process for recovering from out-of-tune based on the target position Pt and the encoder position Pe. Details of the out-of-tune recovery process will be described later.

[0055] According to the drive module 20 of the present embodiment, for example, control in an open loop without feeding back the encoder position Pe every time the STM236 is driven is possible. On the other hand, using the encoder position Pe, out-of-tune caused by external disturbances or the like during the stop of the STM236 can be detected. When out-of-tune is detected, the drive module 20 performs an out-of-tune recovery process according to the target position Pt at the time of stop and the encoder position Pe detected at any time. Thereby, for example, in the drive of the STM236, while avoiding complex processes such as feedback by open-loop control, out-of-tune can be detected and quickly recovered from out-of-tune without restarting or the like for the initialization of the digital camera 1.

[0056] 2-1. Detection and Recovery of Out-of-Tune The operations related to the detection and recovery of out-of-tune in the drive module 20 of the present embodiment will be described with reference to FIGS. 4 to 8.

[0057] FIG. 4 is a flowchart illustrating the operation of the drive module 20 in the present embodiment. The process shown in the flowchart of FIG. 4 starts, for example, when the digital camera 1 is activated and is repeatedly executed by the lens control unit 240 at a predetermined period.

[0058] The lens control unit 240 determines whether the STM 236 is stopped or not (S1) based on the detection result by the encoder 232, for example, as the out-of-tune return control unit 245. 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 at a predetermined period, for example.

[0059] If the STM 236 is stopped (YES in S1), the lens control unit 240 determines whether out-of-tune is detected based on the encoder position Pe and the target position Pt (S2). The lens control unit 240 determines whether out-of-tune has occurred based on whether the difference between the encoder position Pe and the target position Pt is greater than a predetermined out-of-tune threshold. The out-of-tune threshold is preset as a predetermined value (for example, "2") that is less than or equal to one-half of the difference in position corresponding to the period of the drive signal of the STM 236 (in the example of FIG. 3, "8") from the perspective of increasing the possibility of return from out-of-tune due to excitation in step S3 described later, and is stored in the ROM 242 or the like. If out-of-tune is not detected (NO in S2), the lens control unit 240 returns to step S1, for example.

[0060] If out-of-tune is detected (YES in S2), the lens control unit 240 executes the out-of-tune return process after step S3. First, the lens control unit 240 outputs a control signal to the motor driver 237 as the motor control unit 244 so as to perform excitation corresponding to the target position Pt at the time of stopping of the STM 236 based on the voltage data D1, for example (S3). According to such excitation, the STM 236 is rotated so as to be drawn into the rotational position corresponding to the position where the STM 236 is excited by a magnetic field pattern that is the same as the magnetic field pattern that controlled the motor driver 237 at the time of stopping of the STM 236, and the focus lens 230 is driven.

[0061] FIG. 5 is a timing chart for explaining the return operation from out-of-tune due to excitation of the drive module 20 of the present embodiment. FIG. 5 shows an example of the operation at the time of out-of-tune in the example of FIG. 3B where the degree of out-of-tune is relatively small. FIGS. 5(A), (B), and (C) show the time changes of whether to excite STM236 (i.e., on or off of excitation), the encoder position Pe, and the current position Pc, respectively. In FIGS. 5(B) and (C), the target position Pt is indicated by a one-dot chain line.

[0062] In the example of FIG. 5, after the excitation is turned off in response to the stop of STM236, as shown in FIG. 5(B), out-of-tune occurs at time t1, and the encoder position Pe changes from "24" that coincides with the target position Pt at the time of stop to "21". Thereafter, from time t2, excitation corresponding to the target position Pt is performed (S3).

[0063] After turning on the excitation of the target position Pt (S3), the lens control unit 240 waits for a predetermined period (for example, 100 to 200 milliseconds) (S4). The predetermined period is set in advance according to the drive target of STM236 and stored in the ROM242 or the like. For example, as shown in FIG. 5(A), the state of exciting according to the target position Pt continues from time t2 to time t3 as the predetermined period.

[0064] After waiting for the predetermined period (S4), the lens control unit 240 determines, for example, in the same manner as in step S2, whether the difference between the encoder position Pe and the target position Pt is greater than the out-of-tune threshold value, that is, whether out-of-tune is detected (S5).

[0065] In the example of FIG. 5, due to the pulling-in of STM236 in response to the excitation of the target position Pt, the focus lens 230 moves toward the target position Pt. In this case, for example, as shown in FIG. 5(B), since the encoder position Pe changes from the position after out-of-tune and returns to the position before out-of-tune at time t3, the out-of-tune is eliminated and not detected (NO in S5).

[0066] When the difference between the encoder position Pe and the target position Pt is equal to or less than the out-of-tune threshold and no out-of-tune is detected (NO in S5), the lens control unit 240 does not execute the processing after step S6 and ends the processing of this flowchart. In this case, the lens control unit 240 controls the motor driver 237 so as not to excite the STM236 after the time t3 when waiting for a predetermined period, as shown in, for example, FIG. 5(A). Also, as shown in FIG. 5(C), the current position Pc is not changed from before the out-of-tune.

[0067] On the other hand, when the difference between the encoder position Pe and the target position Pt is greater than the out-of-tune threshold and out-of-tune is detected (YES in S5), the lens control unit 240 calculates a return position used for returning from the out-of-tune based on the encoder position Pe and the target position Pt (S6).

[0068] FIG. 6 is a diagram for explaining the operation at the time of out-of-tune that does not return by the excitation of the drive module 20 of the present embodiment. In FIG. 6, similar to FIG. 3(B), the encoder position Pe, the current position Pc, and the target position Pt are shown by being superimposed on a sine wave indicating the voltage of the drive signal in the voltage data D1. FIG. 6(A) shows an example in which after driving the focus lens 230 to the "24" of the target position Pt, the encoder position Pe has moved to the position of "19" due to out-of-tune. FIG. 6(B) shows an example in which, from the state of FIG. 6(A), after waiting for a predetermined period (S4) by excitation according to the target position Pt (S3), the encoder position Pe has not returned to the target position Pt but has moved to the position of "16".

[0069] In the example of FIG. 6, when excitation corresponding to the "24" of the target position Pt is performed, the encoder position Pe moves to the position of "16" that is in the same phase as the target position Pt and closer to the "19" after out-of-tune than the target position Pt. In this case, since the out-of-tune is not eliminated by the excitation of the target position Pt and out-of-tune is detected (YES in S5), the processing after step S6 is executed.

[0070] In step S6, the lens control unit 240 calculates a return position Pr at which the distance from the target position Pt at the stop of the STM236 is an integer multiple of the period of the drive signal in the vicinity of the encoder position Pe according to the following calculation formula. Sn represents the number of steps of the STM236 corresponding to one period of the drive signal. In the following calculation formula, as integer arithmetic, the numerical value after the decimal point is truncated for each operation. (Calculation formula) Pr = Pt + (((Pe - Pt)+Sn / 2) / Sn)*Sn (when Pe > Pt) Pr = Pt - (((Pt - Pe)+Sn / 2) / Sn)*Sn (when Pe < Pt)

[0071] FIG. 7 is a timing chart for explaining the return operation from out-of-tune due to the return position of the drive module 20 of the present embodiment. FIG. 7 shows an operation example at the time of out-of-tune in the example of FIG. 6 where the degree of out-of-tune is relatively large. FIGS. 7(A), (B), and (C) show the time changes of the excitation on or off, the encoder position Pe, and the current position Pc, respectively, in the same manner as FIGS. 5(A), (B), and (C). For example, as shown in FIGS. 7(A) and (B), out-of-tune occurs at time t1, the excitation of the target position Pt is performed at time t2, the encoder position Pe changes, and undetected out-of-tune is detected at time t3 after waiting for a predetermined period.

[0072] In the example of FIG. 7, in the calculation formula of step S6, assuming Pt = 24, Pe = 16, and Sn = 8, since it is the case where Pe < Pt, the return position Pr becomes "16" as follows. Pr = 24 - (((24 - 16)+8 / 2) / 8)*8 = 16

[0073] The lens control unit 240 updates the current position Pc managed as, for example, the motor control unit 244 to the return position Pr calculated in step S6 so as to overwrite it (S7). 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.

[0074] FIG. 8 is a diagram for explaining the operation of the drive module 20 from the state of FIG. 6(B). FIG. 8 shows the encoder position Pe, the current position Pc, and the target position Pt in the same manner as FIGS. 6(A) and (B). In the state of FIG. 8, the current position Pc has been updated from "19" after the phase shift in FIG. 6(B) to "16" of the return position Pr calculated in step S6.

[0075] According to the calculation formula of step S6, as the return position Pr, a position that is in phase with the voltage corresponding to the target position Pt in the sine wave of the voltage of the drive signal is calculated around the phase-shifted position. Thereby, among the plurality of positions that form a magnetic field pattern identical to the magnetic field pattern that controlled the motor driver 237 according to the target position Pt when STM236 stopped, the position closest to the phase-shifted position can be calculated as the return position Pr. In this way, the return position Pr that is consistent with the control of STM236 by the drive signal can be calculated and used for updating the current position Pc managed by the lens control unit 240.

[0076] Thereafter, the lens control unit 240 performs control to drive STM236 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 outputs a drive signal in which the voltage applied to STM236 changes for each position from the motor driver 237 based on the voltage data D1, similar to the drive of STM236 before the phase shift. In the examples of FIGS. 7(A) to 7(C), from time t3, excitation is performed until the focus lens 230 is stopped at the target position Pt by such a drive signal. As STM236 is driven, the current position Pc is updated and the encoder position Pe changes. In this example, the excitation is turned off at time t4 after the current position Pc reaches the target position Pt.

[0077] After executing the drive control of STM236 (S8), the lens control unit 240 ends the processing of this flowchart.

[0078] According to the operation of the above drive module 20, when STM236 is stopped (YES at S1) and out-of-tune is detected (YES at S2), STM236 is excited according to the target position Pt at the time of stop (S3). After waiting for a predetermined period (S4), if out-of-tune is not detected due to the change in the encoder position Pe during excitation (NO at S5), it is considered that the out-of-tune has been eliminated and the subsequent processing is not executed. On the other hand, if out-of-tune is still detected (YES at S5), a return position Pr at which the distance from the target position Pt is an integer multiple of the period of the drive signal for excitation is calculated (S6). Then, after updating the current position Pc managed by the lens control unit 240 to the return position Pr (S7), STM236 is driven to move the current position Pc to the target position Pt (S8).

[0079] After out-of-tune of STM236, when excitation of the target position Pt is performed (S3), STM236 is pulled in at a position where the distance from the target position Pt is an integer multiple of the period of the drive signal, that is, at a position in phase with the target position Pt in the sine wave of the voltage of the drive signal. According to the above drive module 20, as in the examples of FIGS. 6 and 7, even when out-of-tune is not eliminated by excitation of the target position Pt (YES at S5), as the return position Pr, a position in phase closer to the out-of-tuned position than the target position Pt can be calculated (S6). By setting the return position Pr as the current position Pc and moving to the target position Pt by driving STM236 (S7, S8), the actual encoder position Pe, the current position Pc and the target position Pt in management can be made to coincide, and accurate return from out-of-tune can be achieved.

[0080] Also, in the present embodiment, by driving STM236 to the target position Pt before out-of-tune (S8), in addition to eliminating out-of-tune, it is possible to return to the position before out-of-tune.

[0081] 3. Summary As described above, the drive module 20 of the present embodiment drives the focus lens 230 as an example of an element in the digital camera 1 (an example of an imaging device). The drive module 20 includes an STM236 (an example of a motor) that drives the focus lens 230, a motor driver 237 (an example of a motor drive unit) that controls the excitation of the STM236, 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 to manage the position of the focus lens 230. When the drive by the STM236 is stopped, the lens control unit 240 detects a deviation in which 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 a deviation threshold (an example of a predetermined value) (S2). When a deviation is detected (YES in S2), the lens control unit 240 controls the motor driver 237 to eliminate the deviation using a magnetic field pattern that is the same as the magnetic field pattern controlled at the time of stopping the STM236 (S3 to S8).

[0082] According to the drive module 20 as described above, when a deviation is detected during the stop of the STM236 (YES in S2), control is performed to eliminate the deviation using a magnetic field pattern that is the same as the magnetic field pattern by which the motor driver 237 was controlled at the time of stopping the STM236 (S3 to S8). Thereby, even when a deviation occurs due to, for example, an external disturbance or the like, it is possible to accurately return from the deviation.

[0083] In the present embodiment, when a deviation is detected (YES in S2), the lens control unit 240 causes the motor driver 237 to perform excitation of the STM236 according to the target position Pt (an example of a stop position) managed as the position at which the focus lens 230 stops at the time of stopping the STM236 (S3). Thereby, in the case of a relatively small degree of deviation as in the examples in FIGS. 3(B) and 5, it is possible to return to the target position Pt at the time of stopping before the deviation by the pull-in of the STM236 according to the excitation.

[0084] In this embodiment, the motor driver 237 controls the excitation of the STM236 with a drive signal for driving the STM236. When the difference between the encoder position Pe (an example of a detected position), which is detected by the position detection unit during the excitation of the STM236 according to the target position Pt at the time of stop (S3 to S4), and the target position Pt is greater than the demodulation threshold value (YES in S5), the motor driver 237 is controlled to drive the focus lens 230 from the return position Pr, which is an example of the position closest to the encoder position Pe among a plurality of positions where the distance to 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 demodulation can be accurately eliminated and the position before demodulation can be restored. As a result, even when the excitation of the target position Pt (S2) does not cause a return in the case of a relatively large degree of demodulation as in the examples of FIGS. 6 and 7, the return from the demodulation can be accurately achieved.

[0085] In this embodiment, the position detection unit includes an encoder 232 that detects a position corresponding to the rotation of the STM236. According to the encoder 232, for example, the rotation of the STM236 can be detected.

[0086] 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 unit) that images a subject image formed through an optical system, and a focus lens 230 (an example of an element) that is driven by the drive module 20 in the optical system.

[0087] In this embodiment, an 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 including a focus lens 230 driven by the drive module 20.

[0088] According to the above digital camera 1 and interchangeable lens 200, it is possible to accurately return from the demodulation of the STM236 by the operation of the drive module 20.

[0089] (Embodiment 2) Hereinafter, Embodiment 2 of the present disclosure will be described with reference to FIGS. 9 and 10. In Embodiment 1, in the return from out-of-tune, the drive module 20 of the digital camera 1 drove the STM236 to the target position Pt before out-of-tune. In Embodiment 2, a digital camera 1 will be described in which the drive module 20 eliminates out-of-tune without performing such driving.

[0090] Hereinafter, the description of the configuration and operation similar to those of the digital camera 1 according to Embodiment 1 will be omitted as appropriate, and the digital camera 1 according to the present embodiment will be described.

[0091] FIG. 9 is a flowchart illustrating the operation of the drive module 20 in Embodiment 2. The drive module 20 of the present embodiment updates the current position Pc and the target position Pt with the calculated return position Pr (S7A) instead of updating the current position Pc with the calculated return position Pr in the same operation as in Embodiment 1 (S7 in FIG. 4), and then does not perform the drive control of the STM236 (S8 in FIG. 4).

[0092] FIG. 10 is a timing chart for explaining the operation of the drive module 20 of Embodiment 2. FIGS. 10(A), (B), (C), and (D) show the time changes of the excitation to the STM236, the encoder position Pe, the current position Pc, and the target position Pt, respectively, at the time of out-of-tune similar to the examples in FIGS. 6 and 7.

[0093] For example, similar to Embodiment 1, assuming that the difference between the encoder position Pe and the target position Pt shown in FIGS. 10(B) and (D) is larger than the out-of-tune threshold value, an unresolved out-of-tune is detected at time t3 (YES in S5), and the return position Pr is calculated (S6). The lens control unit 240 of the present embodiment updates both the current position Pc in FIG. 10(C) and the target position Pt in FIG. 10(D) with the calculated return position Pr (S7A). Thereafter, the lens control unit 240 ends the processing of the flowchart in FIG. 9. In the present embodiment, since the STM236 is not driven to the target position Pt, the lens control unit 240 turns off the excitation as shown in FIG. 10(A) after the update with the return position Pr at time t3 (S7A).

[0094] Even by the operation of the above-described drive module 20, the encoder position Pe corresponding to the actual rotation of the STM236, the current position Pc and the target position Pt managed by the lens control unit 240 can be made to coincide, and it is possible to accurately return from out-of-tune. Thus, even if it is different from the position before out-of-tune, by eliminating the deviation between the encoder position Pe, the current position Pc in terms of management, and the target position Pt, for example, the STM236 can operate normally from the next drive.

[0095] As described above, in the drive module 20 of the present embodiment, the motor driver 237 (an example of a motor drive unit) controls the excitation of the STM236 by a drive signal for driving the STM236 (an example of a motor). The lens control unit 240 (an example of a control unit) is during the excitation of the STM236 according to the target position Pt (an example of a stop position) when the STM236 stops (S3, S4), the encoder position Pe (an example of a detected position) detected by the encoder 232 and the encoder detection unit 243 (an example of a position detection unit), and when the difference from the target position Pt is greater than the out-of-tune threshold value (an example of a predetermined value) (YES in S5), based on the encoder position Pe and the target position Pt, the return position Pr is calculated as an example of the position closest to the encoder position Pe among a plurality of positions where the distance from the target position Pt is an integer multiple of the period of the drive signal (S6). The lens control unit 240 updates the target position Pt and the current position Pc managed according to the driving amount of the focus lens 230 (an example of an element) to the calculated return position Pr (S7A).

[0096] According to the above-described drive module 20, when the out-of-tune is not eliminated by the excitation of the STM236 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 to the return position Pr (S7A). Thereby, even when the STM236 is not driven, the current position Pc and the target position Pt can be made to coincide with the return position Pr that matches the period of the drive signal, and the out-of-tune can be accurately eliminated.

[0097] (Embodiment 3) Hereinafter, Embodiment 3 of the present disclosure will be described with reference to FIGS. 11 and 12. In Embodiments 1 and 2, in the digital camera 1, the drive module 20 detected and recovered out-of-tune based on the detection result from the encoder 232 that detects the rotation of the STM236. In Embodiment 3, a digital camera 1 using an encoder that detects the movement in which the drive target such as the focus 230 moves straight will be described.

[0098] Hereinafter, the description of the configuration and operation similar to those of the digital camera 1 according to Embodiments 1 and 2 will be omitted as appropriate, and the digital camera 1 according to the present embodiment will be described.

[0099] FIG. 11 is a diagram illustrating the configuration of the drive module 20A in Embodiment 3. The drive module 20A of the present embodiment includes an encoder 238 and a magnet 235 for detecting the position where the focus lens 230 moves straight instead of the encoder 232 (see FIG. 2) of Embodiments 1 and 2 that detects the rotation of the STM236. 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.

[0100] The encoder detection unit 243 detects the position of the focus lens 230 based on the signal from the encoder 238 as the position in the unit system common to the current position Pc and the target position Pt, for example, in the same manner as in Embodiment 1.

[0101] In the drive module 20A of this embodiment, the lens control unit 240 includes, for example, as a functional configuration, an encoder correction unit 246 in addition to the same configuration as in Embodiments 1 and 2. For example, it is considered that the encoder position detected by the encoder 238 does not exactly correspond to the position where the STM236 rotates and the position where the focus lens 230 moves straight due to individual differences of the encoder 238 and the like. The encoder correction unit 246 corrects the encoder position so as to reduce the deviation between such an 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 an example of the position detection unit in the drive module 20A of this embodiment.

[0102] FIG. 12 is a diagram for explaining the encoder correction position in the drive module 20A of Embodiment 3. The encoder correction position indicates the encoder position corrected by the encoder correction unit 246. For example, at each rotation position corresponding to the steps of the STM236, 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. By multiplying the detected encoder position by the thus calculated coefficient α, the encoder position can be corrected. (Relational expression) Encoder correction position = Encoder position * α

[0103] In the drive module 20A of this embodiment, the lens control unit 240 uses, for example, in the same operation as in Embodiment 1, the encoder correction position calculated from the detection result of the encoder 238 instead of the encoder position Pe in steps S2, S5, and S6 of FIG. 3. The lens control unit 240 of the drive module 20A may use the encoder correction position instead of the encoder position Pe in steps S2, S5, and S6 of FIG. 9 in the same operation as in Embodiment 2.

[0104] FIG. 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 STM236, etc., it is considered that the target position Pt and the encoder correction position do not exactly 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 of the period of the drive signal, even when using the encoder correction position, the return position Pr can be accurately calculated in the same manner as in Embodiments 1 and 2.

[0105] According to the return position Pr calculated according to the period of the drive signal, even when an error in the encoder position such as a deviation from the rotational position of STM236 occurs, it is possible to accurately return from detuning. For example, even if the return from detuning is repeated a plurality of times, accumulation of errors can be avoided.

[0106] In the above, an example of using a coefficient for correcting the encoder position has been described. However, for example, correction may be performed by referring to a look-up table generated from the actually measured encoder position or the like in the same manner as above.

[0107] As described above, the position detection unit in the drive module 20A of the present embodiment includes an encoder 238 that detects the linear displacement of the focus lens 230 (an example of an element). The position detection unit corrects the detection result by the encoder 238 according to the rotation of STM236 (an example of a motor), for example, as the encoder detection unit 243 and the encoder correction unit 246, to detect the position of the focus lens 230. Thereby, even with the drive module 20A using the encoder 238 that detects the linear displacement, it is possible to accurately return from detuning based on the corrected encoder correction position.

[0108] (Other Embodiments) As described above, as examples of the technologies disclosed in the present application, Embodiments 1 to 3 have been described. However, the technology in the present disclosure is not limited thereto, and is also applicable to embodiments in which changes, substitutions, additions, omissions, etc. are made as appropriate. Further, it is also possible to combine the respective components described in the above Embodiments 1 to 3 to form a new embodiment. Therefore, other embodiments are exemplified below.

[0109] In each of the above embodiments, an example has been described in which, after the stop of STM236, the excitation corresponding to the target position Pt is turned off and then detuning occurs. The drive module of the present disclosure is not limited to the above example of detuning, and is also applicable when detuning occurs due to a relatively large disturbance or the like during the excitation after the stop. In this case, as the excitation of the target position Pt (S3), by continuing the excitation after the stop, a return from detuning can be performed by the same operation as in each of the above embodiments.

[0110] In each of the above embodiments, an example has been described in which the digital camera 1 drives the focus lens 230 in the AF operation. In the present embodiment, not limited to the AF operation, the focus lens 230 may be driven by the drive modules 20, 20A in the manual focus operation.

[0111] In each of the above embodiments, the drive modules 20, 20A drive the focus lens 230. The drive module of the present embodiment may drive various elements in the digital camera 1 instead of or in addition to the focus lens 230. For example, the drive module may be implemented as any one of a zoom drive unit 211, an OIS drive unit 221, and a diaphragm drive unit 262 that drive the zoom lens 210, the OIS lens 220, and the diaphragm 260, respectively. The encoder 232 of the present embodiment may be arranged to detect the rotation of the motor in each of the drive units 211, 221, 262 in the interchangeable lens 200. A linear encoder 238 similar to that in Embodiment 3 may be arranged to detect the movement of the lens 210, the OIS lens 220, or the diaphragm 260, etc.

[0112] In each of the above embodiments, the lens control unit 240 controls the drive modules 20, 20A. In this embodiment, a dedicated microcomputer or the like provided in the digital camera 1 separately from the lens control unit 240 may control the drive modules 20, 20A.

[0113] In each of the above embodiments, the drive modules 20, 20A drive 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 constitute the drive module. Also in this case, the camera control unit 140 can communicate with each element in the interchangeable lens 200 via, for example, the body mount 150 and the lens mount 250 and perform the same operations as in the above embodiments. Further, in the drive module of this embodiment, the camera control unit 140 may drive an element in the camera body 100. For example, the drive module may be configured as a sensor drive unit 181 that drives the image sensor 110 in the BIS function of the camera body 100.

[0114] 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 unit) that images a subject image formed via an optical system, and an element that is driven by the drive module in at least one of the optical system and the image sensor 110. According to such a digital camera, the operation of the drive module can accurately return from the out-of-tune state of the motor that drives each element.

[0115] In each of the above embodiments, an interchangeable-lens digital camera as an example of an imaging device has been described. However, the imaging device of this embodiment may be a digital camera that is not particularly an interchangeable-lens type. Further, the idea of the present disclosure is applicable not only to digital cameras but also to movie cameras and various electronic devices having imaging functions such as a mobile phone with a camera, a smartphone, or a PC.

[0116] As described above, embodiments have been described as examples of the technology in the present disclosure. For that purpose, the accompanying drawings and detailed description have been provided.

[0117] Therefore, among the components described in the accompanying drawings and the detailed description, there may be not only components essential for solving the problems, but also components not essential for solving the problems for the purpose of exemplifying the above technology. Therefore, just because those non-essential components are described in the accompanying drawings or the detailed description, it should not be immediately determined that those non-essential components are essential.

[0118] Also, since the above-described embodiments are for exemplifying the technology in the present disclosure, various changes, substitutions, additions, omissions, etc. can be made within the scope of the claims or their equivalents.

[0119] (Summary of aspects) Hereinafter, various aspects according to the present disclosure will be listed.

[0120] A first aspect according to the present disclosure is a drive module for driving an element in an imaging device. The drive module includes a motor for driving the element, a motor drive unit for controlling the excitation of the motor, a position detection unit for detecting the position of the element, and a control unit for controlling the motor drive unit to manage the position of the element. The control unit detects a demodulation in which 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 the drive by the motor is stopped. When demodulation is detected, the control unit controls the motor drive unit to eliminate the demodulation using a magnetic field pattern same as the magnetic field pattern controlled at the stop of the motor.

[0121] In a second aspect, in the drive module of the first aspect, when demodulation is detected, the control unit causes the motor drive unit to perform excitation of the motor according to the stop position managed as the position where the element stops at the stop of the motor.

[0122] In the 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 detected position detected by the position detection unit during the excitation of the motor according to the stop position and the stop position is greater than a predetermined value, the control unit drives the element from the position closest to the detected position among the plurality of positions where the distance to the stop position is an integer multiple of the period of the drive signal to the stop position. Thus, the control unit controls the motor drive unit.

[0123] In the 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 detected position detected by the position detection unit during the excitation of the motor according to the stop position and the stop position is greater than a predetermined value, the control unit calculates the position closest to the detected position among the plurality of positions where the distance to the stop position is an integer multiple of the period of the drive signal based on the detected position and the stop position. The control unit updates the position to the calculated position between the stop position and the position managed according to the driving amount of the element.

[0124] In the 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 corresponding to the rotation of the motor.

[0125] In the 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 corrects the detection result by the encoder according to the rotation of the motor to detect the position of the element.

[0126] The seventh aspect is an imaging device, including the drive module of any one of the first to sixth aspects, an imaging unit that images a subject image formed through an optical system, and an element driven by the drive module in at least one of the optical system and the imaging unit.

[0127] The eighth aspect is an interchangeable lens that can be attached to a camera body in an imaging device, including the drive module of any one of the first to sixth aspects and an optical system including an element driven by the drive module.

Industrial Applicability

[0128] The idea of the present disclosure can be applied to a drive module for driving an element in an imaging device by a motor, an imaging device including the drive module, and an interchangeable lens that constitutes the imaging device.

Explanation of Signs

[0129] 1 Digital camera 100 Camera body 110 Image sensor 140 Camera control unit 141 RAM 142 ROM 181 Sensor drive unit 200 Interchangeable lens 210 Zoom lens 211 Zoom drive unit 220 OIS lens 221 OIS drive unit 230 Focus lens 231 Focus drive unit 232, 238 Encoder 237 Motor driver 240 Lens control unit 241 RAM 242 ROM 260 Diaphragm 262 Diaphragm drive unit

Claims

1. A drive module for driving an element in an imaging device, comprising: a motor for driving the element; a motor drive unit for controlling the excitation of the motor; a position detection unit for detecting the position of the element; a control unit for controlling the motor drive unit to manage the position of the element, wherein the control unit: detects a demodulation in which a 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 the drive by the motor is stopped; when the demodulation is detected, controls the motor drive unit to eliminate the demodulation using a magnetic field pattern identical to the magnetic field pattern controlled at the time of stopping the motor. The drive module.

2. When the demodulation is detected, the control unit: causes the motor drive unit to excite the motor according to a stop position managed as a position where the element stops when the motor stops. The drive module according to claim 1.

3. The motor drive unit controls the excitation of the motor by a drive signal for driving the motor, and when a difference between a detected position detected by the position detection unit and the stop position during the excitation of the motor according to the stop position is greater than the predetermined value, the control unit: controls the motor drive unit to drive the element from a position closest to the detected position among a plurality of positions where the distance to the stop position is an integral multiple of the period of the drive signal to the stop position. The drive module according to claim 2.

4. The motor drive unit controls the excitation of the motor by a drive signal for driving the motor, and when a difference between a detected position detected by the position detection unit and the stop position during the excitation of the motor according to the stop position is greater than the predetermined value, the control unit: calculates a position closest to the detected position among a plurality of positions where the distance to the stop position is an integral multiple of the period of the drive signal based on the detected position and the stop position; updates the stop position and a position managed according to the driving amount of the element to the calculated position. The drive module according to claim 2.

5. The position detection unit includes an encoder for detecting a position corresponding to the rotation of the motor. The drive module according to claim 1.

6. The position detection unit includes an encoder that detects a linear displacement of the element, and corrects the detection result by the encoder according to the rotation of the motor to detect the position of the element. The drive module according to claim 1.

7. The drive module according to any one of claims 1 to 6, an imaging unit that images a subject image formed through an optical system, and includes an element driven by the drive module in at least one of the optical system and the imaging unit. An imaging device.

8. An interchangeable lens attachable to a camera body in an imaging device, the drive module according to any one of claims 1 to 6, and includes an optical system including an element driven by the drive module. An interchangeable lens.

Images