JP4652755B2 - Motor control device, imaging device, motor control method, motor control program, and recording medium - Google Patents

Description

  The present invention relates to a motor control device that drives a stepping motor that drives a driven member by rectangular wave driving or sine wave driving, an imaging device that drives a zoom lens and a focus lens by a stepping motor, a motor control method, a motor control program, and The present invention relates to a recording medium storing a motor control program.

  2. Description of the Related Art Conventionally, an imaging apparatus that includes an imaging element such as a CCD, changes a subject magnification with a zoom lens, and focuses with a focus lens is widely known. The mechanism for driving the zoom lens and the mechanism for driving the focus lens are provided with lens driving means, and a stepping motor is often used as the driving source.

  For driving the stepping motor, a driving method for controlling the driving waveform with a rectangular wave and a driving method for controlling the driving waveform with a sine wave are widely known. Patent Document 1 estimates a motor load in sine wave driving. However, a control method by changing the drive voltage or drive current is disclosed. The rectangular wave driving and the sine wave driving have their respective characteristics. When the stepping motor is driven with the rectangular wave, high torque driving can be performed, but the driving sound is large and the power consumption is large. Further, when the stepping motor is driven by a sine wave, both driving sound and power consumption are reduced, but torque is also reduced.

  When driving a zoom lens mechanism or a focus lens mechanism with a stepping motor, if the torque required to move the constituent members cannot be obtained from the stepping motor, a phenomenon of step-out occurs and control becomes impossible. For this reason, when a stepping motor is used in an image pickup apparatus, it is considered to set a drive waveform with a sufficient drive torque so as not to step out during design or trial manufacture.

As described above, when a stepping motor is used as a drive source for a zoom lens mechanism or a focus lens mechanism, a drive waveform having a sufficient drive torque is set at the design or trial production stage. When driving the zoom lens mechanism and the focus lens mechanism, the torque required for driving varies depending on the driving direction and the rotational speed. In general, when a spring is used in the structure of the mechanism, driving in a direction repelling the spring requires high torque, and driving in a direction not repelling the spring can be driven with low torque. In the case of driving in the same driving direction, when the rotational speed is high, it is necessary to drive with higher torque than at low speed. Therefore, conventionally, when determining the drive waveform, the setting is performed assuming the worst condition. Therefore, even if the driving direction and rotational speed can be driven with relatively low torque, high torque driving is performed in accordance with the worst conditions.
JP-A-8-275590

  However, as in the prior art, when driving with a high torque is possible when driving with a low torque, there is a problem in that an extra force is applied to the constituent members and the operating noise is increased.

  In addition, in the control method in which the motor load in sine wave driving is estimated and the driving voltage or driving current is changed as in Patent Document 1, a battery is mainly used as a power source for a small imaging device, and there is a limit to the power supply. For this reason, there is a problem that the driving voltage or driving current of the sine wave is changed, and a sufficient driving torque cannot be obtained only by the sine wave driving.

(Object of invention)
An object of the present invention is to provide a motor driving device, an imaging device, a motor control method, and the like that can reduce the driving sound when driving the driven member, or drive the driven member with a torque suitable for high loads. A motor control program and a recording medium are to be provided.

In order to achieve the above object, the invention described in claim 1 includes a base member, a lens holding member that holds a lens, a regulating member that regulates a moving direction of the lens holding member in an optical axis direction, and the lens. A stepping motor that drives a holding member; an elastic member that is attached to the base member and the lens holding member in parallel to the optical axis direction; and has an elastic force with respect to the base member and the lens holding member; and the stepping motor A first setting means for setting a driving direction of the lens holding member; a second setting means for setting a driving speed of the lens holding member by the stepping motor; the first setting means; and the second setting. Control means for driving the stepping motor by either rectangular wave driving or sine wave driving according to the setting by the means, When the driving direction is set so that the elastic member exerts an elastic force in a direction in which the elastic member separates the base member and the lens holding member by the first setting unit, the control unit sets the second setting unit. The driving direction in which the stepping motor is driven by the rectangular wave driving regardless of the setting by the first setting means, and the elastic member exerts an elastic force in a direction in which the elastic member pulls the base member and the lens holding member by the first setting means. Is set, and when the driving speed set by the second setting means is larger than a predetermined value, the stepping motor is driven by the rectangular wave driving and is set by the second setting means. When the driving speed is smaller than a predetermined value, the stepping motor is driven by the sine wave driving. That.
According to a third aspect of the present invention, there is provided a base member, a lens holding member for holding the lens, a regulating member for regulating the moving direction of the lens holding member in the optical axis direction, and a stepping for driving the lens holding member. A control method for a lens driving device comprising: a motor; and an elastic member attached to the base member and the lens holding member in parallel with an optical axis direction and having an elastic force with respect to the base member and the lens holding member. And
A first setting step of setting a driving direction of the lens holding member by the stepping motor;
A second setting step of setting a driving speed of the lens holding member by the stepping motor;
A control step of driving the stepping motor by either rectangular wave driving or sine wave driving according to the settings in the first setting step and the second setting step,
In the control step, in the first setting step, when the driving direction is set such that the elastic member exerts an elastic force in a direction to separate the base member and the lens holding member, the second setting step is performed. Regardless of the setting by the setting means, the stepping motor is driven by the rectangular wave drive,
In the first setting step, when the driving direction is set such that the elastic member exerts an elastic force in a direction in which the base member and the lens holding member are attracted, the second setting means When the set driving speed is larger than a predetermined value, the stepping motor is driven by the rectangular wave driving, and when the driving speed set by the second setting means is smaller than the predetermined value, the stepping by the sine wave driving. A motor is driven.

  According to the present invention, a motor driving device, an imaging device, a motor control method, and the like that can reduce driving sound when driving a driven member or drive a driven member with a torque suitable for a high load, A motor control program or a recording medium can be provided.

  As shown in the following examples.

  FIG. 1 is a block diagram showing an electrical configuration of an imaging apparatus according to an embodiment of the present invention. In the figure, reference numeral 300 denotes a lens barrel, which includes a zoom lens 312 and an image sensor 316 described below. A DC motor 301 is used to drive a lens 312 (hereinafter referred to as a zoom lens) for changing the subject magnification. For driving the zoom lens 312, other motors such as a step motor and an ultrasonic motor can be used as long as drive specifications other than the DC motor are satisfied. A linear sensor 302 is used to detect the position of the zoom lens 312. In addition to the linear sensor, an encoder or other detection means may be used for detecting the position of the zoom lens 312. Reference numeral 303 denotes an aperture unit that limits the amount of light entering the image sensor 316 in accordance with an instruction from the control unit 306, which will be described later, and can maintain an image to be captured at an appropriate exposure. A step motor 314 is used to drive a lens 313 (hereinafter referred to as a focus lens) for focusing on a subject. As described above, since the step motor 314 independent of the zoom lens 312 is used for driving the focus lens 313, the focus lens 313 can be driven to a free position within a range that does not interfere with the zoom lens 312. Reference numeral 315 denotes a photo interrupter, which is used when the position of the focus lens 313 is initialized. Reference numeral 316 denotes an image sensor, which passes through the zoom lens 312 and receives a subject image focused by the focus lens 313. A signal processing circuit 304 performs predetermined processing such as color conversion and gamma processing on the image signal photoelectrically converted by the image sensor 316. Reference numeral 305 denotes a memory such as a card medium, which records an image signal from the signal processing circuit 304.

  In FIG. 1, reference numeral 306 denotes a control unit that controls the entire camera, and monitors the outputs of the linear sensor 302, the photo interrupter 315, and the like inside the lens barrel, while the step motor 314, the DC motor 301, and the aperture unit 303. A control instruction is issued to the drive waveform driver 307. The signal processing circuit 304 and the memory 305 are also controlled. The drive waveform driver 307 is mainly composed of an H bridge circuit, and the drive waveform driver 307 switches the polarity of the input voltage (control of the rotation direction) with respect to the DC motor 301 in accordance with an instruction from the control unit 306. The step motor 314 outputs either a rectangular wave or a sine wave as a drive waveform according to an instruction from the control unit 306.

  A part of the internal circuit configuration for driving the step motor of the drive waveform driver 307 is shown in FIG. In FIG. 2, reference numeral 600 denotes a drive unit that drives the step motor 314, and has two input terminals 602 and 603 to which signals A and B are input. When the rectangular wave signals 701 (A1) and 702 (B1) shown in FIG. 3 are input to the terminals 602 and 603, the step motor 314 is driven by the rectangular wave, and the sine wave signal 801 ( When A2) and 802 (B2) are input, the step motor 314 is driven by a sine wave. In general, when the step motor 314 is driven by a rectangular wave, a high torque drive can be performed with respect to a sine wave drive at the same peak current, but there is a characteristic that a drive sound becomes louder than a sine wave drive.

  Returning to FIG. 1, reference numeral 309 denotes an electrically erasable / recordable non-volatile memory, such as an EEPROM. The memory 309 stores a program for the control unit 306 and parameters for controlling the imaging apparatus. A mode dial 310 is used for switching setting of each function mode such as power-off, shooting mode, playback mode, PC connection mode, and the like. A zoom switch 308 is used for a wide / tele switching operation. Reference numeral 311 denotes a release switch, which is used for a shooting start instruction.

  FIG. 5 is a perspective view showing a mechanism portion of the focus lens 313 of the lens barrel 300. In the figure, reference numeral 500 denotes a base member that supports the entire focus unit. On this base member 500, a step motor 314 for driving the focus lens 313 and a photo interrupter 315 for detecting the position are attached. A guide bar 502 is further attached to the base member 500, and a folder 501 with a focus lens 313 is attached to the guide bar 502. The rotation output of the step motor 314 is transmitted to the nut 505 attached to the folder 501 via the screw 503 or the like, so that the folder 501 can move along the guide bar 502 in the optical axis direction. A tension coil spring 504 is attached between the base member 500 and the folder 501, and the folder 501 is always moved toward the base member 500 by the spring force of the tension coil spring 504. As a result, the guide bar 502 can be stably moved, but on the other hand, a large torque is required to drive the folder 501 in a direction repelling the spring force. Even in a direction in which the driving direction does not repel the spring force, a large torque is required as compared with a low speed when the driving speed is high. The torque required for driving the step motor 314 can be measured at the trial production stage of the product or in the manufacturing process.

  Therefore, in this embodiment, the torque necessary for the driving direction and the driving speed of the folder 501 is measured in the product prototype stage or the manufacturing process, and the driving conditions obtained from the results are stored in the nonvolatile memory 309 in advance. When the step motor 314 is driven, the control unit 306 acquires the drive condition from the nonvolatile memory 309 and instructs the drive waveform driver 307 to output the rectangular wave drive or the sine wave drive. I have to.

  As a driving condition stored in advance in the non-volatile memory 309, for the “driving direction”, for example, when the focus lens 313 is extended, a torque against the urging force of the tension coil spring 504 is required. Since the torque required for this is larger than a predetermined amount, when the rectangular wave drive suitable for high load is selected and the focus lens 313 is retracted, the urging force of the tension coil spring 504 can be used. Since the torque required for the driving direction may be smaller than a predetermined amount, a driving condition for selecting a sine wave driving suitable for silent operation is stored. As for the “drive speed”, for example, when the focus lens 313 is driven at a high speed, a torque larger than a predetermined amount is required. Therefore, when a rectangular wave drive suitable for a high load is selected and the focus lens 313 is driven at a low speed, Since a torque smaller than a predetermined amount may be used, a driving condition for selecting a sine wave driving suitable for silent operation is stored. In addition, even when the driving torque required in the driving direction is smaller than the predetermined torque, if the driving speed is faster than the predetermined speed, the driving condition is such that the rectangular wave driving suitable for the high load is selected as the driving of the stepping motor. Remember.

  FIG. 6 is a flowchart showing control at the time of driving the focus lens 313 by the control unit 306 of the imaging apparatus having the above-described configuration. When the user operates the release switch 311, the focus lens 313 is driven to enter an AF (autofocus) process, and in this AF process, the control unit 306 determines the drive direction and drive speed of the step motor 314. Determine (S100). When the drive direction is determined, the control unit 306 compares the drive condition with the drive direction stored in the nonvolatile memory 309, that is, determines whether or not the torque required for the drive direction at this time is greater than a predetermined amount (S101). If it is determined that the torque required in the driving direction is larger than the predetermined amount (Yes in S101), the drive waveform driver 307 is instructed to drive the step motor 314 with a rectangular wave (S104).

  On the other hand, when it is determined that the torque required in the driving direction is smaller than the predetermined amount (No in S101), the driving speed is compared with the driving condition stored in the nonvolatile memory 309, that is, the torque required for the driving speed at this time is It is determined whether or not the driving speed at this time is faster than the predetermined speed (S102). If it is determined that the driving speed is higher than the predetermined speed (Yes in S102), The drive waveform driver 307 is instructed to drive the step motor 314 by rectangular wave driving suitable for high load (see FIG. 3) (S104). If it is determined that the drive speed is equal to or lower than the predetermined speed (No in S102), the drive waveform driver 307 is instructed to drive the step motor 314 with a sine wave suitable for silence (S103).

  According to the above embodiment, the stepping motor 314, which is a drive source for driving the driven member (focus lens mechanism, zoom lens mechanism), is driven by a rectangular wave drive suitable for high loads and a sine wave drive suitable for silence. In the imaging device that can be switched to, the driving of the stepping motor 314 is selected from rectangular wave driving and sine wave driving in accordance with the direction and / or driving speed of the driven member. Specifically, the driving condition stored in advance in the nonvolatile memory 309 is compared with the driving direction and / or driving speed at that time, and either rectangular wave driving or sine wave driving is selected as appropriate. . Therefore, it is possible to reduce the driving noise when driving the driven member, or to drive the driven member with a torque suitable for high loads.

  The present invention is not limited to the above embodiment, and may be applied to a system constituted by a plurality of devices or an apparatus constituted by a single device. A storage medium storing software program codes for realizing the functions of the above embodiments is supplied to a system or apparatus, and a computer (or CPU or MPU) of the system or apparatus reads and executes the program codes stored in the storage medium. Of course, it will be completed. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. As a storage medium for supplying the program code, for example, a floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, magnetic tape, nonvolatile memory card, ROM, or the like is used. be able to.

  Further, by executing the program code read out by the computer, not only the functions of the above-described embodiments are realized, but also the OS running on the computer based on the instruction of the program code is one of the actual processes. Needless to say, a case where the functions of the above-described embodiments are realized by performing the processing in part or in whole is included.

  Further, the driven member is not limited to the focus lens mechanism or the zoom lens mechanism, but may be a shutter blade, a diaphragm member, or the like.

It is a block diagram which shows the schematic circuit structure of the camera which concerns on one Example of this invention. FIG. 2 is a circuit diagram showing a part in the drive waveform driver of FIG. 1. It is a figure which shows the rectangular wave used for the drive of the stepping motor of FIG. It is a figure which shows the sine wave used for the drive of the stepping motor of FIG. It is a perspective view which shows the mechanism part of the focus lens of a lens barrel. It is a flowchart which shows operation | movement of the principal part of the camera which concerns on one Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 300 Lens barrel 301 DC motor 302 Linear sensor 304 Signal processing circuit 306 Control part 307 Drive waveform driver 309 Non-volatile memory 312 Zoom lens 313 Focus lens 314 Step motor 316 Imaging element 502 Guide bar 503 Screw 504 Pulling coil spring

Claims (5)

A base member;
A lens holding member for holding the lens;
A regulating member for regulating the moving direction of the lens holding member in the optical axis direction;
A stepping motor for driving the lens holding member;
An elastic member attached to the base member and the lens holding member in parallel with the optical axis direction, and having an elastic force with respect to the base member and the lens holding member;
First setting means for setting a driving direction of the lens holding member by the stepping motor;
Second setting means for setting a driving speed of the lens holding member by the stepping motor;
Control means for driving the stepping motor by either rectangular wave driving or sine wave driving according to the setting by the first setting means and the second setting means,
When the driving direction is set such that the elastic member exerts an elastic force in a direction in which the elastic member separates the base member and the lens holding member by the first setting means, the second setting is performed. Regardless of the setting by means, the stepping motor is driven by the rectangular wave drive,
The driving direction is set by the first setting means so that the elastic member exerts an elastic force in a direction in which the elastic member pulls the base member and the lens holding member together, and is set by the second setting means. The stepping motor is driven by the rectangular wave driving when the driving speed is greater than a predetermined value, and the stepping motor is driven by the sine wave driving when the driving speed set by the second setting means is smaller than a predetermined value. A lens driving device. Imaging means;
A lens driving device according to claim 1,
The lens driving device performs focusing by driving the lens holding member. A base member, a lens holding member that holds the lens, a regulating member that restricts the moving direction of the lens holding member in the optical axis direction, a stepping motor that drives the lens holding member, the base member, and the lens holding member An elastic member attached in parallel to the optical axis direction and having an elastic force with respect to the base member and the lens holding member,
A first setting step of setting a driving direction of the lens holding member by the stepping motor;
A second setting step of setting a driving speed of the lens holding member by the stepping motor;
A control step of driving the stepping motor by either rectangular wave driving or sine wave driving according to the settings in the first setting step and the second setting step,
In the control step, in the first setting step, when the driving direction is set such that the elastic member exerts an elastic force in a direction to separate the base member and the lens holding member, the second setting step is performed. Regardless of the setting by the setting means, the stepping motor is driven by the rectangular wave drive,
In the first setting step, when the driving direction is set such that the elastic member exerts an elastic force in a direction in which the base member and the lens holding member are attracted, the second setting means When the set driving speed is larger than a predetermined value, the stepping motor is driven by the rectangular wave driving, and when the driving speed set by the second setting means is smaller than the predetermined value, the stepping by the sine wave driving. A method of controlling a lens driving device, characterized by driving a motor. The program for making a computer perform each process of the image processing method of Claim 3. A computer-readable recording medium on which the program according to claim 4 is recorded.

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