JP2017227825A - Lens drive device and lens drive control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens drive device and a lens drive control method that prevent FB control from becoming unstable even in a state where lenses interfere.SOLUTION: A lens drive device has: a stepping motor that drives lenses; a voltage control unit that controls a voltage to be applied to the stepping motor; a position instruction unit that instructs a rotary position of the stepping motor; and a rotary detection sensor that detects the rotary position of the stepping motor. When the position instruction unit implements the position instruction on the basis of a control deviation, the control deviation is calculated from a difference between position detection information to be detected by the rotary detection sensor and position information to be instructed by the position instruction unit, and the control deviation exceeds a reference level (S5), and a determination of whether a change direction of the control deviation is reversed or not is made (S9). When detecting the reverse of the change direction, a direction of a change in voltage to be applied by the voltage control unit is limited (S13).SELECTED DRAWING: Figure 6

Description

  The present invention relates to a lens driving device and a lens driving control method for controlling the driving of a stepping motor for moving a lens in a lens-integrated camera and an interchangeable lens of a lens interchangeable camera.

  In the conventional zoom lens, since both the focus lens and the zoom lens are driven by the cam, the movement ranges in the optical axis direction of both do not overlap at the same time. However, with the miniaturization of digital cameras and interchangeable lenses, there are now lens barrels that overlap the movement range of the focus lens and zoom lens. In such a lens barrel, the focus lens and the zoom lens may interfere with each other due to a zooming operation.

  Therefore, in a lens barrel in which zoom driving is performed electrically, when the distance between the focus lens and the zoom lens becomes a certain value or less, the lens mirror moves along the path different from the focus lens position information. A cylinder has been proposed (see Patent Document 1). According to this lens barrel, it is possible to prevent the focus lens and the zoom lens from interfering during zooming.

JP 2006-322984 A

  In the lens barrel disclosed in Patent Document 1, zooming driving is electrically performed. However, in a lens barrel in which a zoom operation is manually performed, the maximum speed of zoom driving cannot be limited during the zoom operation. It is difficult to avoid interference. Also, if the power-off process is not performed normally and the zoom operation is performed with the power off, the focus lens and zoom lens may start to operate in this case. However, it is difficult to avoid lens interference.

  If the lens driving load changes suddenly while the lens is interfering, natural motor vibration (resonance) is likely to occur. When natural vibration of the motor occurs, when feedback (hereinafter abbreviated as “FB”) control (voltage control and speed control) using a stepping motor to drive the focus lens is performed, the unstable state of the FB control continues. May end up. If the FB control becomes unstable, the position of the focus lens cannot be detected with high accuracy during autofocus, the focus is increased, and it takes time to focus.

  The present invention has been made in view of such circumstances, and provides a lens driving device and a lens driving control method that prevent the FB control from becoming unstable even when the lens interferes. The purpose is to provide.

  In order to achieve the above object, a lens driving device according to a first aspect of the present invention includes a stepping motor that drives a lens, a voltage control unit that controls a voltage applied to the stepping motor, and a position that indicates a rotational position of the stepping motor. A follow-up delay that calculates a control deviation from a difference between an instruction unit, a rotation detection sensor that detects a rotation position of the stepping motor, position detection information detected by the rotation detection sensor, and position information indicated by the position instruction unit A calculating unit, and when the position indicating unit is performing a position instruction based on the control deviation, the control deviation exceeds a reference level, and when the reversal of the change direction of the control deviation is detected, The direction of change of the applied voltage by the voltage control unit is limited.

  In the lens driving device according to the second invention, in the first invention, the direction of change in the applied voltage to be limited is a direction in which the voltage is lowered.

  In the lens driving device according to a third aspect of the present invention, in the first aspect, the voltage control unit detects the second inversion in the direction of the control deviation when the control deviation is smaller than the reference level. The restriction on the direction of change of the applied voltage is continued.

  In the lens driving device according to a fourth aspect of the present invention, in any one of the first to third aspects, the voltage control unit is configured such that the control deviation is smaller than the reference level and the control deviation is in the direction of the control deviation. When the inversion of 2 is detected and the applied voltage rises, the above restriction is released.

  A lens drive control method device according to a fifth aspect of the present invention is a stepping motor that drives a lens, a voltage control unit that controls a voltage applied to the stepping motor, a position instruction unit that indicates a rotational position of the stepping motor, A difference between position detection information detected by the rotation detection sensor and position information instructed by the position indicating unit in a lens drive control method of a lens driving device having a rotation detection sensor for detecting a rotation position of the stepping motor; Whether the control deviation exceeds a reference level and the change direction of the control deviation is reversed when the position instruction unit performs position instruction based on the control deviation. When the determination is made and the reversal of the change direction is detected, the direction of change in the applied voltage by the voltage control unit is limited.

  According to the present invention, it is possible to provide a lens driving device and a lens driving control method that prevent the FB control from becoming unstable even when the lens interferes.

1 is a block diagram mainly showing an electrical configuration of a camera according to an embodiment of the present invention. It is a figure explaining the interference of a lens in the camera concerning one embodiment of the present invention. It is a figure explaining change of load in the camera concerning one embodiment of the present invention. It is a graph which shows the control in the camera which concerns on one Embodiment of this invention. It is a block diagram which shows the voltage control limit process of the camera which concerns on one Embodiment of this invention. It is a flowchart which shows the operation | movement of the FB control minimum voltage value determination of the camera which concerns on one Embodiment of this invention. It is a flowchart which shows the operation | movement of the FB control minimum voltage value determination of the camera which concerns on one Embodiment of this invention. It is a wave form diagram which shows the control deviation waveform and voltage waveform of the camera which concern on one Embodiment of this invention. It is a graph which shows the modification of the control in the camera which concerns on one Embodiment of this invention.

  Hereinafter, an example applied to a digital camera (hereinafter abbreviated as “camera”) as an embodiment of the present invention will be described. That is, an example applied to a camera will be described as an example of a lens driving device that moves a lens in the optical axis direction. In this camera, the subject image formed by the optical lens in the lens barrel is converted into image data by the imaging unit, and the subject image is arranged on the back of the main body based on the converted image data. Live view is displayed on the display unit, and still image and moving image data is recorded on the recording medium.

  In addition, a focus lens and a zoom lens are provided in the lens barrel. The focus lens is moved in the optical axis direction by a stepping motor, and the zoom lens is manually moved in the optical axis direction. The movement ranges of both lenses partially overlap (see FIG. 2 described later). The stepping motor that drives the focus lens is controlled in drive voltage by FB control. In this drive control, the difference between the current position of the focus lens and the drive commanded position is set as a tracking delay, and FB control is performed based on a control deviation that is a difference between the tracking delay and the target tracking delay.

  In addition, when the zoom lens hits the focus lens, the load changes, which makes the FB control unstable. In the present embodiment, when the control deviation exceeds the reference level, instability of the FB control is prevented by limiting the direction of change in the drive voltage applied to the stepping motor (FIGS. 4, 5, and 5 to be described later). 6 S5, S13, etc.).

  In this specification, unstable means a state in which, when the control deviation changes in vibration, the voltage control also becomes in vibration, and the vibration is difficult to converge. The load refers to the state where the nut attached to the rotating shaft (lead screw) of the stepping motor and the lens frame are integrated (normal: loaded), and the state where the nut and the lens frame are separated (when the lens interferes: no) Load).

  Hereinafter, a preferred embodiment using a camera to which the present invention is applied will be described with reference to the drawings. FIG. 1 is a block diagram showing a mechanical configuration of a lens driving unit of a camera according to an embodiment of the present invention and mainly an electrical configuration related to lens driving of the camera. The camera may be an interchangeable lens system camera including an interchangeable lens that can be attached to and detached from the camera body, or the lens barrel and the camera body may be configured integrally.

  The lens driving unit 1 is disposed in an interchangeable lens of a lens-integrated camera or an interchangeable lens camera. In the lens driving unit 1, there are an optical lens (hereinafter abbreviated as “lens”) 2, a lens frame 3, guide shafts 4 a and 4 b, a spring 5, a stepping motor 6, a lead screw 7, a scale magnet 8, a GMR (Giant Magneto). Resistive Effect: A sensor 9 and a photo interrupter 10 are provided.

  The lens 2 has a plurality or a single optical lens and forms a subject image. The lens 2 is held by the lens frame 3. The guide shaft 4a and the guide shaft 4b provided in parallel therewith are shafts extending along the optical axis direction of the lens 2, and are fixed to a lens barrel or the like. The lens 2 is suspended by a spring 5 and is provided between the lens frame 3 and a lens barrel fixing member, and applies an urging force to the lens frame 3 in the right direction in the figure.

  The lens frame 3 described above includes a fixing portion 3a extending in a direction perpendicular to the optical axis direction of the lens 2, and a fitting portion 3b that is integral with the fixing portion 3a and is fitted to the guide shaft 4b. The lens frame 3 also has a through hole 3c through which the lead screw 7 passes and a light-shielding honey 3e. The light-shielding honey 3e is integrated with the fixed portion 3a and is provided on one end side of the fixed portion 3a. The light shield 3e blocks light projected from the light emitting unit of the photo interrupter 10 when the lens 2 moves to the reference position.

  The stepping motor 6 receives a two-phase pulse signal composed of an A phase and a B phase as a motor drive signal from a motor drive circuit (motor driver) 24, and rotates. The stepping motor 6 is a stepping motor that drives a lens. The rotational drive shaft of the stepping motor 6 is integral with the lead screw 7. For this reason, the lead screw 7 rotates forward and backward in accordance with the motor drive signal applied to the stepping motor 6.

  When the lead screw 7 is rotated forward or backward, the lens 2 moves along the optical axis direction via the nut 11 engaged with the lead screw 7. The nut 11 is separate from the lens frame 3. The lens frame 3 is pulled rightward in FIG. 1 by the spring 5, and the periphery of the through hole 3 c is in contact with the nut 11 that meshes with the lead screw 7. Since the rotation stop (not shown) of the nut 11 is provided on the lens frame 3, when the lead screw 7 rotates, the nut 11 moves to the right or left, and the lens frame 3 applied thereto also moves in the optical axis direction. Move to.

  The scale magnet 8 is integrally provided on one end side of the lead screw 7, and S poles and N poles are alternately magnetized along the circumferential surface. The GMR sensor 9 is disposed at a position facing the scale magnet 8, and outputs a two-phase signal according to the magnetic field generated by the S pole and N pole of the scale magnet 8. Based on the detection signals of the scale magnet 8 and the GMR sensor 9, the relative rotational position of the stepping motor 6 (the relative position of the lens 2 in the optical axis direction) can be detected.

  The photo interrupter 10 is fixed to a lens barrel or the like, and has a light emitting unit and a light receiving unit. When the lens 2 moves to the reference position, the light projection from the light emitting unit is blocked by the light blocking hood 3e. When the light-receiving unit is in a light-shielded state, the output changes, thereby detecting that the lens 2 is at the reference position. In other words, the absolute position of the lens 2 can be detected by the light shield 3e and the photo interrupter 10. A position detection signal from the photo interrupter 10 is output to the IO port 32.

  As described above, in the lens driving unit 1 according to the present embodiment, the nut 11 is linearly moved by the rotation of the lead screw 7 driven by the stepping motor 6, and the lens frame 3 is moved to the guide shafts 4 a and 4 b by the biasing force of the spring 5. Move along. As a result, the lens 2 fixed to the lens frame 3 is driven in the optical axis direction. A scale magnet 8 is attached to the tip of the lead screw 7 at a position facing the GMR sensor 9, and when the lead screw rotates forward or reverse, the scale magnet 8 also rotates in the same direction. The GMR sensor 9 functions as a rotation detection sensor that detects the rotation position of the stepping motor.

  The output of the GMR sensor 9 is connected to the amplifier circuit 21. The amplifier circuit 21 amplifies the two-phase analog sensor output signals from the GMR sensor 9 and performs noise removal processing on the sensor signals. The amplified sensor signal processed by the amplifier circuit 21 is output to the A / D converter 33 and the binarization circuit 22.

  The binarization circuit 22 binarizes the two-phase sensor output signals from the amplifier circuit 21 and outputs the binarization signal to an up / down counter (two-phase counter) 34. In binarization, the binarization circuit 22 inputs the threshold voltage from the D / A converter 35 and binarizes using the threshold voltage.

  The microcomputer 30 includes a CPU (Central Processing Unit) 31 and its peripheral circuits, and executes the entire camera by controlling each part in the camera according to a program stored in the memory 39. Specifically, the microcomputer 30 generates various signals for driving the stepping motor 6 in accordance with, for example, various signals from the lens driving unit 1. The peripheral circuits include an IO (Input / Output) port 32, an A / D (Analog / Digital) converter 33, an up / down counter 34, a D / A (Digital / Analog) converter 35, a pulse generator 36, and a communication port 37. A timer 38 and a memory 39 are provided.

  The IO port 32 receives a position detection signal from the photo interrupter 10 and outputs a signal indicating that the lens 2 is at the reference position to the CPU 31 based on the position detection signal.

  The A / D converter 33 inputs the A-phase and B-phase amplified sensor signals from the amplifier circuit 21, performs AD conversion on each signal, and converts the A-phase and B-phase amplified sensor signals into digital data. Output to the CPU 31.

  The D / A converter 35 receives a digital value corresponding to the threshold voltage from the CPU 31, converts it into an analog voltage, and outputs it to the binarization circuit 22 as a threshold voltage. The midpoint potential of the amplified sensor signal varies depending on the characteristics of the GMR sensor 9 and the amplifier circuit 21. Therefore, the midpoint potential of the A phase and the B phase is stored in advance in the memory 39 as an adjustment value, and the binarization circuit 22 performs binarization using the midpoint potential as a threshold voltage.

  The up / down counter 34 receives a binarized signal from the binarizing circuit 22 and performs up / down counting. The GMR sensor 9 outputs A-phase and B-phase sensor signals, and performs up / down counting each time a binarized signal is input. Thereby, it can be determined in which direction the scale magnet 8 is rotating forward or backward, that is, in which direction the lens 2 is moving.

  The memory 39 includes an electrically rewritable volatile memory (for example, DRAM (Dynamic Random Access Memory) and the like) and an electrically rewritable nonvolatile memory (for example, a flash ROM (Flash Read Only Memory) and the like). Have. The memory 39 stores various data such as a program to be executed by the CPU 31, various lens adjustment values (for example, values relating to the above-mentioned midpoint potential), lens driving setting values, and the like. Data (adjustment value) indicating the relationship between the position pulse (rotation position) of the stepping motor and the detection pulse (detection position) by the GMR sensor 9 is stored as a setting value for driving the lens.

  The timer 38 performs a timing operation for generating a control cycle of feedback control and measuring the time of various lens operations. It also has a calendar function and the like. The communication port 37 is a port for exchanging signals with the outside of the CPU 31. In this embodiment, various communications are performed via the communication port 37. For example, a setting signal is sent from the communication port 37 to the motor drive circuit 24.

  The pulse generator 36 receives a control signal from the CPU 31 and generates a clock signal (pulse signal) output to the motor drive circuit 24 for driving the stepping motor 6. That is, the pulse generator 36 outputs a clock signal to the motor drive circuit 24 and advances the excitation position of the stepping motor.

  The motor drive circuit 24 is supplied with a power supply voltage from the motor power supply 23, receives a clock signal from the pulse generator 36 and a setting signal from the communication port 37, and is driven by the stepping motor 6 with a two-phase voltage signal. Output a signal. The motor drive circuit 24 adjusts the maximum applied voltage of the motor drive signal based on the setting signal from the CPU 31 when outputting the motor drive signal. The motor power source 23 has a power source such as a battery, and is made constant voltage by a constant voltage circuit or the like and supplies power to the motor drive circuit 24.

  In generating the motor drive signal, the CPU 31 in the microcomputer 30 performs a calculation based on the sensor output signal detected by the GMR sensor 9, manages the drive pulse output from the motor drive circuit 24, sets the drive speed, and drives the voltage. Perform various arithmetic processing of digital data necessary for setting and feedback control. The CPU 31, the communication port 37, and the motor drive circuit 24 function as a voltage control unit that controls the voltage applied to the stepping motor. The CPU 31, the pulse generator 36, and the motor drive circuit 24 function as a position instruction unit that instructs the rotation position of the stepping motor.

  The CPU 31 functions as a follow-up delay calculation unit that calculates a control deviation from the difference between the position detection information detected by the rotation detection sensor and the position information indicated by the position instruction unit. When the position indicating unit is performing a position instruction based on the control deviation, if the control deviation exceeds the reference level (see S5 Yes in FIG. 6) and the reversal of the change direction of the control deviation is detected (see S9 Yes in FIG. 6). ), Limiting the direction of change of the applied voltage by the voltage controller (see S13 and S15 in FIG. 6). The direction of change in the applied voltage to be restricted is the direction in which the voltage is lowered (see FIGS. 4C and 4D and S11 Yes in FIG. 6). The voltage control unit continues to limit the change direction of the applied voltage until the control deviation becomes smaller than the reference level and the second inversion of the direction of the control deviation is detected (FIGS. 4C and 4D). ) Times T2 to T3, S5No in FIG. 6 → S23 Yes in FIG. 7 → S13 in FIG. The voltage control unit releases the restriction when the control deviation becomes smaller than the reference level and the second inversion in the direction of the control deviation is detected and the applied voltage is increased (FIG. 4C). (D) times T2 to T3, S5No in FIG. 6 → S23 → S27 in FIG.

  In the present embodiment, the FB control when driving the stepping motor 6 is performed as follows. A GMR sensor 9 attached to the tip of the lead screw 7 detects the current position. The CPU 31 determines the difference between the detected current position and the drive instruction position for the stepping motor 6 as a tracking delay, obtains a control deviation that is the difference between the tracking delay and the target tracking delay, and performs stepping based on this control deviation. 6 is controlled. The sign of the control deviation is positive when the tracking delay is large with respect to the target tracking delay, and is negative when the tracking delay is small with respect to the target tracking delay.

  Next, interference between the focus lens 2a and the zoom lens 2b in the present embodiment will be described with reference to FIG. The lens according to the present embodiment has different focus adjustment ranges on the long focus side (Tele) and the short focus side (Wide). Note that an intermediate focal length between the long focal point and the short focal point is intermediate between the focus adjustment ranges shown in the upper and lower parts of FIG.

  The lens focus adjustment range L1 of the focus lens 2a on the long focus side (Tele) is shown on the upper side of FIG. The focus lens 2a is movable between the closest position P1 and the infinity position P2. 2 shows a lens focus position adjustment range L2 of the focus lens 2a on the short focus side (Wide). The focus lens 2a is movable between a close position P3 and an infinite position P4.

  The zoom lens 2b is at the position P5 on the long focus side (Tele) and at the position P6 on the short focus side (Wide), and is movable within the zoom lens manual operation range L3. As can be seen from FIG. 2, the interference range L4 is within the movable range of the focus lens 2a and also within the movable range of the zoom lens 2b.

  For this reason, in the interference range L4, if the moving speed of the zoom lens 2b is faster than the moving speed of the focus lens 2a, the zoom lens 2b may collide with the focus lens 2a and interfere. Further, when the power is turned off, the lens may interfere when performing a zoom operation from the long focus side (Tele) to the short focus side (Wide).

  Next, a state in which the zoom lens 2b interferes with the focus lens 2a and the load changes will be described with reference to FIG. Normally, the nut 11 and the lens frame 3 attached to the lead screw 7 operate integrally because the lens frame 3 that holds the focus lens 2 a is biased by the spring 5. However, when the zoom lens 2b collides with and interferes with the focus lens 2a, the nut 11 attached to the lead screw 8 and the lens frame 3 are separated from each other, so that the load on the motor is reduced.

  On the other hand, when the power is not turned off normally, a load change also occurs when the zoom operation is performed with the power off. Specifically, when the focus lens 2a is driven by the stepping motor 6 in a state where the load is reduced due to the interference between the lenses and the nut 11 is separated from the lens frame 3, only the nut 11 begins to move. Thereafter, when the nut 11 catches up with the lens frame 3, the motor load changes at this point, and the load increases.

  Next, a control deviation suppression process at the time of lens drive control in the present embodiment will be described with reference to FIG. In FIG. 4, a graph (a) shows a temporal change of the drive voltage when the control deviation suppression process is not performed in the present embodiment, and a graph (b) is a control when the control deviation suppression process is not performed in the present embodiment. Shows the change in deviation over time. A graph (c) shows a temporal change of the drive voltage when the control deviation suppression process is performed in the present embodiment, and a graph (d) is a time variation of the control deviation when the control deviation suppression process is performed in the present embodiment. Showing change.

  As described above, when the zoom lens 2b and the focus lens 2a interfere with each other, the motor load changes. When the load suddenly increases at the motor load change timing T2, a natural vibration of the motor occurs, and the detected position changes in terms of vibration relative to the indicated position (see graph (b) in FIG. 4). The control deviation is the difference between the follow-up delay and the target follow-up delay, where the current position is detected by the GMR sensor 9 and the difference between the detected position and the position instructed by the CPU 31 is the follow-up delay. If the detected position changes with respect to the instructed position, the control deviation also vibrates accordingly. When the control deviation vibrates, the drive voltage of the stepping motor 6 is controlled along with the vibration of the control deviation, so that the excitation voltage setting value also vibrates.

  This vibration will be described with reference to graphs (a) and (b) of FIG. From time T0 to T2, the zoom lens 2b and the focus lens 2a are in an interference state, and the stepping motor 6 is unloaded. From time T1 to T2 (FIG. 4 (a): Ta), the load becomes light, and as shown in the graph (a), the excitation voltage set value (driving voltage of the stepping motor 6) Vset decreases in the FB control. . In addition, Vin1 shows FB control minimum voltage value (initial value).

  At time T2, the nut 11 catches up with the lens frame 3, and the motor load changes at this point. When the motor load changes, a normal state (loaded) is obtained. In this state, the load suddenly increases and motor natural vibration occurs, and as shown in the graph (b), the control deviation is positive from time T2 to T3 (FIGS. 4A and 4B: Tb). The vibration does not converge easily (the natural vibration continues with the vibration of the excitation voltage setting value). For this reason, as shown in the graph (a), the excitation voltage set value V also vibrates due to the vibration of the control deviation.

  Therefore, in this embodiment, as shown in the graphs (c) and (d), the vibration of the control deviation is converged quickly by limiting the excitation voltage setting value according to the change of the control deviation.

  A value larger than the maximum value of the control deviation in a state where the lens does not interfere (normal: loaded state) is provided as the reference level Ref. The reference level Ref is set to a value corresponding to the driving speed instructed to the focus lens 2a because the control deviation does not become zero depending on the driving speed instructed to the focus lens 2a. Since there is no margin for the motor torque in the high speed range of the drive speed, the control deviation does not become zero but becomes large (plus), and in the low speed range, there is a margin for the motor torque, so the control deviation becomes smaller than zero. (It becomes negative).

  From the timing when the control deviation exceeds the reference level Ref and the control deviation starts to decrease until the control deviation is smaller than the reference level Ref and the control deviation increases, the change direction of the excitation voltage set value is limited. That is, in the graph (d), times t1 to t2, t3 to t4, t5 to t6, and t7 to t8 correspond to this period.

  As for the natural vibration of the motor, the higher the excitation voltage set value, the faster the vibration converges. Further, in order to prevent step-out in the FB control, the excitation voltage setting value is increased when the control deviation becomes large. For this reason, the direction of control with restriction is set to a direction of decreasing the excitation voltage setting value.

  As described above, there is a limit in the case of decreasing the excitation voltage setting value. The excitation voltage setting value is limited by setting the excitation voltage setting value to be clipped by setting the FB control minimum voltage value Vin2 to a voltage value higher than the FB control minimum voltage initial value Vin1 shown in the graph (a). Make sure that the value does not drop. That is, at the times t1 to t2, t3 to t4, t5 to t6, and t7 to t8 in the graph (c), the excitation voltage setting values at the times t1, t3, t5, and t7 are respectively set to the minimum FB control at the next setting timing. By setting the voltage value Vin2, the excitation voltage setting value is limited so as not to decrease. From time t8 to T3 (FIG. 4 (d): Td), the control deviation is less than the reference level Ref, so the restriction on the excitation voltage set value is released. In the graph (d), the black circle (●) indicates the excitation voltage set value limit start point (when the control deviation starts to decrease after exceeding the reference level), and the white circle (◯) indicates the excitation voltage set value limit release point. (When the control deviation starts to increase).

  As described above, in this embodiment, the time until the vibration of the control deviation converges is reduced by limiting the voltage applied to the stepping motor 6 (excitation voltage setting value) according to the control deviation. That is, in the graphs (a) and (b) in which the control according to the present embodiment is not performed, the control deviation vibrates between the times T2 and T3 (FIGS. 4A and 4B: Tb), and the excitation voltage is increased accordingly. The set value is also vibrating. On the other hand, in the graphs (c) and (d) for performing the control according to the present embodiment, the control deviation vibrates between the times T2 and t8 (FIG. 4 (d): Tc). The vibration of is converged. By performing such control, the time during which the control deviation vibrates can be shortened.

  Next, the control deviation suppression process in this embodiment is demonstrated using FIG. The CPU 31 calculates a control deviation, and obtains a new excitation voltage setting value by increasing / decreasing the current excitation voltage setting value based on a voltage control value obtained by digital signal processing of the calculated control deviation.

  In FIG. 5, the voltage control value generated by the CPU 31 based on the control deviation value is added to the current excitation voltage setting value (# 101), and the FB control maximum voltage value limit process (# 102) is performed. The FB control maximum voltage value limit process (# 102) compares the added voltage value with the FB control maximum voltage value (initial value), and when the added voltage value is larger than the FB control maximum voltage value. Clip to the FB control maximum voltage value. The FB control maximum voltage value (initial value) is initially set as the maximum excitation voltage setting value applied to the stepping motor 6.

  Further, the current excitation voltage setting value is compared with the initial value of the FB control minimum voltage value, and the FB control minimum voltage value determination process (# 104) is performed. In this FB control minimum voltage value determination process (# 104), when the current excitation voltage setting value is larger than the initial value of the FB control minimum voltage value, the current excitation voltage setting value is processed into the FB control minimum voltage value limit process. Output to. On the other hand, if the current excitation voltage setting value is smaller than the initial value of the FB control minimum voltage value, the initial value of the FB control minimum voltage value is output to the FB control minimum voltage value limit process. Detailed operation of this FB control minimum voltage determination value process will be described later with reference to FIGS.

  When the FB control maximum voltage value limit process is performed, the FB control minimum voltage value limit process (# 103) is performed. In this FB control minimum voltage value limit process, the FB control minimum voltage value from the FB control minimum voltage value determination process (# 104) is compared with the voltage value subjected to the FB control maximum voltage value limit process, and the FB control maximum voltage value is determined. When the limit-processed voltage value is smaller than the FB control minimum voltage value, the clip is clipped to the FB control minimum voltage value. The voltage value subjected to the FB control minimum voltage value limit processing is output as a new excitation voltage setting value. On the other hand, when the voltage value subjected to the FB control maximum voltage value limit processing is equal to or greater than the FB control minimum voltage value, the voltage value subjected to the FB control maximum voltage value limit processing is output as a new excitation voltage setting value.

  The processing for limiting the excitation voltage setting value not to decrease at the times t1 to t2, t3 to t4, t5 to t6, and t7 to t8 in the graphs (c) and (d) of FIG. 4 described above is the FB control in FIG. This corresponds to minimum voltage value determination processing (# 104) and FB control minimum voltage value limit processing (# 103). The block diagram of FIG. 5 is described as processing by software of the CPU 31, but part or all of it is configured by hardware such as a digital processing circuit, and the microcomputer is inside the CPU 31 or outside the CPU 31. It may be provided inside 30.

  Next, the operation of determining the minimum FB control voltage value in the present embodiment will be described using the flowcharts shown in FIGS. 6 and 7 and the waveform diagram shown in FIG. Note that the flowcharts shown in FIGS. 6 and 7 are realized by the CPU 31 controlling each part in the camera according to a program stored in the memory 39. This flow is repeatedly executed at predetermined time intervals, and the FB control minimum voltage value is determined each time. In the voltage waveform diagram shown in the lower part of FIG. 8, the solid line Lpre indicates the excitation voltage setting value when the control deviation suppression process in the present embodiment is not performed, and the alternate long and short dash line Laft indicates the control deviation suppression in the present embodiment. An FB control minimum voltage value when processing is performed is shown.

  When the operation of determining the FB control minimum voltage value shown in FIGS. 6 and 7 is started, it is first determined whether or not the vehicle is accelerating or low-speed (S1). The stepping motor 6 is controlled by any one of acceleration, constant speed, and deceleration. Here, the determination is made based on the speed control performed by the CPU 31 to the motor drive circuit 24 via the communication port 37.

  If the result of determination in step S1 is not acceleration or constant speed, the flag is reset (S19). This flag is a flag for determining whether the determination control deviation value is exceeded, and is set when the determination control deviation value is exceeded (see S5 and S7 described later). Although the flag is reset in the initial state, after the flag is set in step S7, if the determination in step S1 is deceleration, the flag is reset.

  On the other hand, if the result of determination in step S1 is acceleration or constant speed, a determination control deviation value is determined (S3). Determination control deviation value determination is to set a reference level Ref corresponding to the driving speed instructed to the focus lens. That is, the reference level Ref shown in FIG. 4D is determined according to the driving speed instructed to the focus lens.

  Once the determination control deviation value is determined, it is next determined whether or not the current control deviation is greater than or equal to the reference level Ref (S5). Here, the current control deviation (the difference between the current position detected by the GMR sensor 9 and the position instructed to drive is defined as the tracking delay, and the control deviation which is the difference between the tracking delay and the target tracking delay), and in step S3. The determination is made by comparing the determined determination control deviation value (reference level Ref).

  If the result of determination in step S5 is No, that is, if the current control deviation is less than the reference level, it is determined whether or not the flag is set (S21). As described above, this flag is set when the control deviation exceeds the reference level. Normally, it is in the region G in FIG. 8 and the drive speed is accelerated, but the control deviation is less than the reference level and the flag is not set. Therefore, the result of determination in step S21 is No, and FB control is performed. As a process for determining the minimum voltage value, an initial value is set in step S29 (see FB control minimum voltage (initial value) input to the FB control minimum voltage value determination process of # 104 in FIG. 5).

  When the load increases rapidly, the current control deviation becomes equal to or higher than the reference level as a result of the determination in step S5. In this case, a flag is set (S7). When the load increases rapidly, the FB control minimum voltage value is determined in steps S13, S15, and S17 according to the current control deviation and voltage control value, as will be described later.

  When the flag is set, it is determined whether or not the current control deviation is equal to or less than the previous control deviation (S9). Here, the determination is made by comparing the current control deviation with the previous control deviation. The current control deviation is stored in the memory 39 for use in the next processing in step S5. While the control deviation is increasing as in the area A of FIG. 7, the result of the determination in step S9 is No.

  If the result of determination in step S9 is that the current control deviation is greater than the previous control deviation, an initial value is determined as FB control minimum voltage value determination (S17). Here, the initially set FB control minimum voltage value (see one input value of the FB control minimum voltage value determination process of # 104 in FIG. 5) is set as the determined FB control minimum voltage value. In region A in FIG. 8, the new excitation voltage setting value tends to increase, so the minimum FB control voltage value remains the initial value (the flow passes S9 No → S17 in FIG. 6).

  If the result of determination in step S9 is that the current control deviation is less than or equal to the previous control deviation, it is next determined whether or not the voltage control value is less than 0 (S11). Here, the determination is made based on the voltage control value instructed by the CPU 31 (see one input value of addition processing # 101 in FIG. 5).

  As a result of the determination in step S11, if the voltage control value is not less than 0, that is, if it is 0 or more, the new excitation voltage setting value is set as the FB control minimum voltage value determination (S15). Here, even if the control deviation starts to decrease as shown in region B of FIG. 8, the voltage control value shows a change in phase that is delayed from the control deviation due to the processing time of the digital processing, so the new excitation voltage setting value tends to increase. . Therefore, the FB control minimum voltage value is increased in accordance with the new excitation voltage setting value (the flow passes S9 Yes → S11 No → S15 in FIG. 6).

  If the result of determination in step S11 is that the voltage control value is less than 0, the current excitation voltage setting value is set as the FB control minimum voltage value determination (S13). Here, the current excitation voltage setting value instructed by the CPU (see one input value of the FB control minimum voltage value determination processing unit of # 104 in FIG. 5) is set as the determined FB control minimum voltage value. When the control deviation decreases and the voltage control value becomes negative as in region C of FIG. 8, the new excitation voltage setting value tends to decrease. Here, by setting the FB control minimum voltage value to the current excitation voltage, the current excitation voltage is maintained without lowering the new excitation voltage setting value at the next setting (as a flow) , S9Yes → S11Yes → S13 in FIG. 6).

  Returning to step S5, when the region C shown in FIG. 8 is passed, the control deviation becomes smaller than the reference level, and the determination result is No. Therefore, the process proceeds to step S21 to determine whether or not the flag is set (S21). In the state where the region C has passed the region C and entered the region D in FIG. 8, since the flag is set in step S7, this step S21 is determined as Yes.

  Subsequently, it is determined whether or not the current control deviation is equal to or less than the previous control deviation (S23). Here, the determination is made by comparing the current control deviation with the previous control deviation.

  If the result of determination in step S23 is that the current control deviation is less than or equal to the previous control deviation, the process proceeds to step S13, where the current excitation voltage set value is determined as the FB control minimum voltage value determination (S13). In the region D of FIG. 8, since the control deviation is initially decreased, the excitation voltage set value is prevented from decreasing as in the case of the region C (the flow is S5 No in FIG. 6 → FIG. 7). S21Yes → S23Yes → S13 in FIG. 6).

  On the other hand, if the result of determination in step S23 is that the current control deviation is not less than or equal to the previous control deviation, that is, if the current control deviation is greater than the previous control deviation, whether or not the voltage control value is greater than zero is determined. Determine (S25).

  If the voltage control value is negative as a result of the determination in step S25, the process proceeds to step S13, where the current excitation voltage setting value is set as the FB control minimum voltage value determination (S13). This state corresponds to the region E in FIG. 8, and even when the control deviation increases, while the voltage control value is negative, the excitation voltage set value is prevented from decreasing as in the regions C and D ( As a flow, S5No in FIG. 6 → S21Yes in FIG. 7 → S23No → S25No → S13 in FIG. 6).

  If the result of determination in step S25 is that the voltage control value has turned positive, the flag is reset (S27), and an initial value is set as FB control minimum voltage value determination (S29). When the voltage control value becomes positive at timing F in FIG. 8, the flag is released, the FB control minimum voltage value is returned to the initial value, and the restriction is released (the flow is S5 No in FIG. 6 → S21 Yes in FIG. 7 → S23No → S27 → S29).

  In this way, in the flow for determining the minimum FB control voltage value, in order to perform the minimum FB control voltage value limit process (see # 103 in FIG. 5), the minimum FB control voltage value determination process (see # 104 in FIG. 5) is performed. Is going. When the control deviation exceeds the reference level (S5 Yes in FIG. 6) and the reversal of the change direction of the control deviation is detected (S9 Yes in FIG. 6), the direction of change in the voltage applied by the voltage control unit is limited. (S13, S15 in FIG. 6).

  The determination of acceleration or constant speed in step S1 is because the limitation of the minimum FB control voltage value may not be released when the command speed is changed from the high speed range to the low speed range. That is, the excitation voltage set value in the low speed range is in a decreasing direction, but the flag is set when the FB control minimum voltage value is limited in the high speed range. Therefore, a state occurs in which the excitation voltage setting value does not decrease compared to a state where the command speed is not changed and the operation is performed at a low speed. In order to avoid this phenomenon, the flag is reset when the speed of the stepping motor is being decelerated.

  Next, a first modification of the control deviation suppression process will be described using FIG. In one embodiment of the present invention, the control deviation suppression process was performed between times T2 and T3 (FIGS. 4A and 4B: Tb), but this period was indefinite. That is, when the current control deviation becomes larger than the previous deviation and the voltage control value becomes 0 or more (see S23No → S25Yes in FIG. 7, timing F in FIG. 8), the control deviation suppression process is stopped. It was. On the other hand, in this modification, the time for performing the control deviation suppression process is set to a predetermined time.

  That is, in this modification, since the weight of the zoom lens and the focus lens is determined and the driving speed instructed to the focus lens is also determined, an average time during which the control deviation vibrates is determined (this time) The time T4 is set based on this), and the excitation voltage set value is not lowered until that time.

  Specifically, at time T2, which is the motor load change timing, the FB control minimum voltage value Vin2 is increased from the initial value to the maximum controllable value, and the excitation voltage setting value is clipped. At time T4 when the average time during which the control deviation oscillates is reached, the FB control minimum voltage value Vin2 is returned to the initial value. That is, time T2 to T4 (FIG. 9: Te) is a period in which the excitation voltage set value is limited so as not to decrease. Further, when the time T4 elapses (FIG. 9: Tf), the control deviation is less than the reference level Ref, so that the excitation voltage set value is not limited. In this modification as well, a value larger than the maximum value of the control deviation when the zoom lens is not interfering is provided as the reference level Ref. The reference level Ref is a value corresponding to the driving speed instructed to the focus lens.

  According to this modification, the power consumption is slightly increased, but the time (time T2 to T4) during which the control deviation vibrates can be shortened.

  Next, a second modification of the control deviation suppression process will be described. In one embodiment and the first modification of the present invention, drive pulses are continuously output from the CPU 31 to the stepping motor 6 through the communication port 37 and the motor drive circuit 24. On the other hand, in this modification, the method for applying the drive pulse is different.

  That is, in this modification, the control deviation exceeds the reference level because the rotor in the stepping motor 6 maintains a predetermined position and keeps stationary when no drive pulse signal is applied. The driving pulse is temporarily stopped at the time. Thereby, the time during which the control deviation varies may be shortened.

  In this modification as well, a value larger than the maximum value of the control deviation when the zoom lens is not interfering is provided as the reference level Ref. The reference level Ref is a value corresponding to the driving speed instructed to the focus lens.

  As described above, in one embodiment or a modification of the present invention, the lens driving device includes the stepping motor 6 that drives the lens and the voltage control unit that controls the voltage applied to the stepping motor (e.g., CPU 31, communication). Port 37, motor driving circuit 24), a position indicating unit (for example, CPU 31, pulse generator 36, motor driving circuit 24) for indicating the rotational position of the stepping motor, and a rotation detection sensor (for detecting the rotational position of the stepping motor). For example, it has a GMR sensor 9). Then, when the position instruction unit performs position instruction based on the control deviation, the difference between the position detection information detected by the rotation detection sensor and the position information instructed by the position instruction unit is set as a tracking delay, and the tracking delay The control deviation is calculated from the difference between the target tracking delay and the target tracking delay, and it is determined whether the control deviation exceeds the reference level (for example, S5 in FIG. 6) and the change direction of the control deviation is reversed (for example, in FIG. S9) When the reversal of the change direction is detected, the direction of change in the voltage applied by the voltage control unit is limited (for example, S13 in FIG. 6). Even in a state where the lens interferes, the FB control can be prevented from becoming unstable. That is, during the feedback control of the stepping motor, the vibration of the motor is detected to limit the direction of the voltage control. Therefore, the vibration time can be shortened, the focus can be quickly adjusted, and a photo opportunity is not missed.

  In the embodiment and modification of the present invention, the detection of the interference of the zoom lens is detected based on whether or not the reference value of the control deviation is exceeded. Alternatively, the impact may be detected as soon as possible by an impact sensor such as an acceleration sensor instead of the control deviation.

  In the embodiment and the modification of the present invention, the GMR sensor 9 is used as the lens position detection sensor. However, the present invention is not limited to this, and an optical encoder or the like can detect the position. Any sensor may be used. In addition, the stepping motor is used as the lens driving device. However, the present invention is not limited to this, and FB control is performed based on the difference between the lens driving position indicated by the driving device and the lens position detected by the sensor. Any lens driving device can be used. In addition, the examples of the focus lens 2a and the zoom lens 2b have been described as the interfering lenses. However, the present invention is not limited thereto, and the first focus lens group and the second focus lens group may be used. Of course, interference may also occur.

  In one embodiment or modification of the present invention, the CPU 31 performs addition processing (# 191), FB control maximum voltage value limit processing (# 102), FB control minimum voltage value limit processing (# 103), and FB control. The minimum voltage value determination process (# 104) is processed by software. However, the present invention is not limited to this, and a part of each part may be configured by software and executed by configuring a hardware circuit inside or outside the microcomputer 30. The hardware configuration is not limited to a hardware circuit, and may be a hardware configuration such as a gate circuit generated based on a programming language written in Verilog, or hardware using software such as a DSP (Digital Signal Processor). A configuration may be utilized. You may combine these suitably.

  In the embodiment and the modification of the present invention, the digital camera is used as the photographing device. However, the camera may be a digital single lens reflex camera, a mirrorless camera, or a compact digital camera, and may be a video. Cameras for moving images such as cameras and movie cameras may be used. Further, mobile phones, smartphones, personal digital assistants, personal computers (PCs), tablet computers, cameras incorporated in game machines, medical cameras, microscopes, etc. It may be a camera for scientific equipment, an on-vehicle camera, or a surveillance camera. In any case, the present invention can be applied to any device that may interfere with the lens.

  Of the techniques described in this specification, the control mainly described in the flowchart is often settable by a program and may be stored in a recording medium or a recording unit. The recording method for the recording medium and the recording unit may be recorded at the time of product shipment, may be a distributed recording medium, or may be downloaded via the Internet.

  In addition, regarding the operation flow in the claims, the specification, and the drawings, even if it is described using words expressing the order such as “first”, “next”, etc. It does not mean that it is essential to implement in this order.

  The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, you may delete some components of all the components shown by embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

DESCRIPTION OF SYMBOLS 10 ... Interchangeable lens, 1 ... Lens drive part, 2 ... Lens, 2a ... Focus lens, 2b ... Zoom lens, 3 ... Lens frame, 3a ... Fixed part, 3b・ ・ ・ Fitting part, 3c ・ ・ ・ Through hole, 3e ・ ・ ・ Shading shield, 4a ・ ・ ・ Guide shaft, 4b ・ ・ ・ Guide shaft, 5 ・ ・ ・ Spring, 6 ・ ・ ・ Stepping motor, 7 ・..Lead screw, 8 ... Scale magnet, 9 ... GMR sensor, 10 ... Photo interrupter, 11 ... Nut, 21 ... Amplifier circuit, 22 ... Binary circuit, 23. ..Motor power supply, 24 ... motor drive circuit, 30 ... microcomputer, 31 ... CPU, 32 ... IO port, 33 ... A / D converter, 34 ... up / down counter 35 ... D / A converter, 36 ... Pulse generator, 37 ... communication port, 38 ... timer, 39 ... memory

Claims (5)

A stepping motor that drives the lens;
A voltage control unit for controlling a voltage applied to the stepping motor;
A position indicating unit for indicating the rotational position of the stepping motor;
A rotation detection sensor for detecting a rotation position of the stepping motor;
A follow-up delay calculation unit that calculates a control deviation from a difference between position detection information detected by the rotation detection sensor and position information indicated by the position instruction unit;
With
When the position instruction unit performs a position instruction based on the control deviation, when the control deviation exceeds a reference level and the reversal of the change direction of the control deviation is detected, the voltage control unit applies the application Limit the direction of voltage change,
A lens driving device.   The lens driving device according to claim 1, wherein the direction of change in the applied voltage to be limited is a direction in which the voltage is decreased.   The voltage control unit continues to limit the direction of change of the applied voltage until the control deviation becomes smaller than the reference level and the second inversion of the direction of the control deviation is detected. The lens driving device according to claim 1.   The voltage control unit detects the second inversion in the direction of the control deviation when the control deviation is smaller than the reference level, and releases the restriction when the applied voltage increases. The lens driving device according to any one of claims 1 to 3, wherein A stepping motor that drives the lens;
A voltage control unit for controlling a voltage applied to the stepping motor;
A position indicating unit for indicating the rotational position of the stepping motor;
A rotation detection sensor for detecting a rotation position of the stepping motor;
In a lens driving control method of a lens driving device having:
Calculating a control deviation from the difference between the position detection information detected by the rotation detection sensor and the position information indicated by the position indicating unit;
When the position indicating unit is performing a position instruction based on the control deviation, it is determined whether the control deviation exceeds a reference level and the change direction of the control deviation is reversed,
When detecting the reversal of the change direction, the voltage control unit limits the direction of change in the applied voltage.
And a lens driving control method.

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