JP2015130753A - Actuator drive device and control method therefor, and imaging apparatus and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce zero-crossing distortion of a current of duty ratio-current characteristics by an actuator drive device.SOLUTION: A coil La101 and a coil Lb102 of a two-phase stepping motor 100 are connected to terminals A, B, and S (common terminals) respectively, and PWM (pulse-width modulation) outputs of HB (half-bridge) circuits 120A, 120B, and 120S are applied. A control part 115 synchronizes the respective outputs of the HB circuits 120A, 120B, and 120S by controlling period signal generation parts 110A, 110B, and 110S, controls a duty ratio by setting periods of respective outputs of the terminals A and B to periods which are twice or half as long as the output of the common terminal S, or controls timing of switching by setting the outputs of the terminals A, B, and C to the same period and setting a delay rate corresponding to the duty ratio. A drive device performs pseudo control through reverse conduction near the zero-cross point for the coil La101 and the coil Lb102.

Description

  The present invention relates to a technique for improving the linearity of a duty ratio-current characteristic in the vicinity of a zero cross point in an actuator driving device.

In a conventional motor driving circuit using bipolar driving, a method for controlling outputs of a plurality of half-bridge (HB) circuits is known. The potential difference between the output of the common terminal of the HB circuit with a duty ratio of 50% and the output of the half-bridge circuit on the coil side generates an on period in which current flows and a short period in which no current flows. It is determined (see Patent Document 1).
FIG. 6A is a block diagram showing a conventional two-phase stepping motor driving apparatus using bipolar driving. The two-phase stepping motor 100 includes an A-phase coil La101, a B-phase coil Lb102, and a magnetized rotor 103 therein. HB circuit 120A is connected to terminal A of A-phase coil La101. HB circuit 120B is connected to terminal B of B-phase coil Lb102. The HB circuit 120S is connected to a common terminal S that connects the A-phase coil La101 and the B-phase coil Lb102.

The HB circuits 120A, 120B, and 120S can select a state of sucking current, a state of supplying a current, and an open state in which no current flows by an input signal to the input terminals in1 and in2. The control circuit 130 controls the HB circuits 120A, 120S, and 120B. The control circuit 130 selects the state of the HB circuit 120A by the control signals output from the terminals Vpa and Vna, and drives the stepping motor 100. Similarly, the HB circuit 120B is controlled by control signals from the terminals Vpb and Vnb of the control circuit 130, and the HB circuit 120S is controlled by control signals from the terminals Vps and Vns of the control circuit 130.
FIG. 6B is a circuit diagram showing the configuration of the HB circuits 120A, 120S, and 120B. Each circuit includes a Pch (channel) FET element 201 and an NchFET element 202, and the Pch driver 203 drives the PchFET element 201 and the Nch driver 204 drives the NchFET element 202.

With reference to FIG. 7, the energization method in the said motor drive device is demonstrated.
The output signal of the HB circuit 120S has a duty ratio set to 50%. On the other hand, the HB circuits 120A and 120B on the coil side synchronize with the HB circuit 120S and control each output. The energization amount is is as follows when the duty ratios of the terminal A of the HB circuit 120A and the terminal B of the HB circuit 120B are Da% and Db%, respectively.
-About terminal A energization amount isa = (50-Da) * Im / 100
-About terminal B energization amount isb = (50-Db) * Im / 100
However, the direction in which current flows from the common terminal S to the terminal A or B is positive. Also, Im is the maximum amount of current that flows when the two terminals are fixed to H (High) and L (Low) during one cycle.

Taking the common terminal S and the terminal A as examples, the behavior of current will be described.
First, a rectangular wave voltage having a duty ratio of 50% at the common terminal S and a ratio of the on period to the off period of 1: 1 is applied. When this is at the H (High) level, that is, when a motor drive voltage is output, the common terminal S functions as a power supply terminal for supplying current. During this period, when the terminal A outputs an L (Low) level, that is, a ground potential, current flows from the common terminal S to the terminal A through the A-phase coil La101. When the terminal A is at the H level, the terminals are short-circuited and no current flows.
Next, during a period in which the common terminal S is at the L level, if the terminal A is at the H level, current flows from the terminal A through the coil La101 to the common terminal S. When the terminal A is at the L level, the terminals are short-circuited and no current flows.
Thus, a desired energization direction and energization amount can be obtained by combining the energization period and the short period.

Japanese Patent Publication No. 3799300

However, in the conventional driving device, in order to perform current control in the energization period and the short period in either direction, the duty ratio-current characteristics near the zero value of the current value, that is, near the zero cross point (FIG. 8: Distortion may occur in the broken line graph g). This distortion is a major problem in realizing smooth micro-step driving in, for example, a stepping motor driving circuit using bipolar driving.
An object of the present invention is to reduce zero cross distortion in duty ratio-current characteristics in an actuator driving device.

In order to solve the above-described problem, an apparatus according to a first aspect of the present invention includes a first half bridge circuit having a first output terminal connected to an actuator, and a second output terminal connected to the actuator. A second half-bridge circuit having a first periodic signal generator for outputting a drive signal by pulse width modulation from the first half-bridge circuit, and a second half-bridge circuit for outputting a drive signal by pulse width modulation from the second half-bridge circuit. A period of the first pulse width modulation signal by the two period signal generation unit, a period of the second pulse width modulation signal by the second period signal generation unit and a period of the second pulse width modulation signal by the second period signal generation unit are set to different periods; The control part which changes the duty ratio of the drive signal which 1 half-bridge circuit outputs is provided.
An apparatus according to a second aspect of the present invention includes a first half bridge circuit having a first output terminal connected to an actuator, and a second half bridge circuit having a second output terminal connected to the actuator. A first period signal generator for outputting a drive signal by pulse width modulation from the first half bridge circuit; a second period signal generator for outputting a drive signal by pulse width modulation from the second half bridge circuit; The first pulse width modulation signal by the first period signal generation unit and the second pulse width modulation signal by the second period signal generation unit are set to the same period, and the first half bridge circuit with respect to the second half bridge circuit A control unit for changing the switching timing and the duty ratio of the drive signal.

  According to the present invention, zero cross distortion in the duty ratio-current characteristic can be reduced.

It is a figure which shows the electricity supply method which concerns on 1st Embodiment of this invention. It is a figure which shows the electricity supply method which concerns on 2nd Embodiment of this invention. It is a figure which shows the electricity supply method which concerns on 3rd Embodiment of this invention. It is a block diagram which shows the structural example of the drive device which concerns on embodiment of this invention. It is a figure which shows the system configuration | structure of a general camera. It is a block diagram (A) of the drive device of the two-phase stepping motor by bipolar drive, and a diagram (B) showing a half bridge circuit. It is a figure which shows the electricity supply method in a prior art. It is explanatory drawing of a duty ratio-current characteristic.

Hereinafter, each embodiment of the present invention will be described. In each embodiment, a motor is exemplified as an actuator. However, the energization control of this embodiment is not limited to driving a stepping motor, and can be applied to drive control of various actuators. The energization control described in FIGS. 6 and 7, that is, the method of changing one timing of the rising edge or the falling edge on one side of the drive voltage waveform is referred to as “first energization method”.
[First Embodiment]
FIG. 4 is a block diagram illustrating a configuration example of the actuator driving device according to the first embodiment of the present invention. The configuration of the two-phase stepping motor 100 as an actuator is the same as that in FIG. The first half bridge circuit connected to the first output terminal A is referred to as a first HB circuit 120A, and the second half bridge circuit connected to the second output terminal S is referred to as a second HB circuit 120S. The third half bridge circuit connected to the third output terminal B is referred to as a third HB circuit 120B. Note that the configuration of each HB circuit is the same as that in FIG.
The first periodic signal generator 110A outputs a drive signal by pulse width modulation from the first HB circuit 120A. The first pulse width modulation signal from the first periodic signal generator 110A is input to the first HB circuit 120A. The second periodic signal generator 110S outputs a drive signal by pulse width modulation from the second HB circuit 120S. The second pulse width modulation signal from the second periodic signal generator 110S is input to the second HB circuit 120S. The third periodic signal generator 110B outputs a drive signal by pulse width modulation from the third HB circuit 120B. The third pulse width modulation signal from the third periodic signal generator 110B is input to the third HB circuit 120B.
The control unit 115 performs control to set the periods of the first pulse width modulation signal and the second pulse width modulation signal to different periods and to change the duty ratio of the drive signal output from the first HB circuit 120A. Further, the control unit 115 performs control to set the periods of the third pulse width modulation signal and the second pulse width modulation signal to different periods, and to change the duty ratio of the drive signal output from the third HB circuit 120B.

  Hereinafter, energization control of the two-phase stepping motor 100 in the present embodiment will be described. FIG. 1 is a waveform diagram for explaining energization control in the present embodiment. In the example shown in FIG. 1, the period of the first pulse width modulation signal at the coil-side terminal A is twice the period of the second pulse width modulation signal at the common terminal S and is synchronized. Further, when the output of the common terminal S is always the motor drive voltage (hereinafter referred to as H) and the output of the coil side terminal is always the ground potential (hereinafter referred to as L) in one cycle, the unit time Let I be the amount of current that flows per hit. The current flows from the common terminal S toward the terminal A on the coil side. At this time, if the PWM cycle of the common terminal S is Ts and the PWM cycle of the coil-side terminal A is Ta, the relationship of “Ta = 2 × Ts” is established. Note that the value of the duty ratio of the common terminal S is 50% (a constant value).

上式について、端子Ａのデューティ比Ｄｕｔｙ（Ａ）を変化させた場合の、通電量ｉを求める過程を以下に示す。 In the present embodiment, the energization amount i during the period Ta is expressed as follows with respect to the duty ratio of the terminal A (denoted as Duty (A)).

A process of obtaining the energization amount i when the duty ratio Duty (A) of the terminal A is changed with respect to the above equation is shown below.

が成立する期間では、端子Ｓ及びＡの出力が共にＨであるため、端子Ｓと端子Ａとの間には電流は流れない。 (1) When 0 ≦ Duty (A) ≦ 25% For time t

In the period in which the above is established, since the outputs of the terminals S and A are both H, no current flows between the terminal S and the terminal A.

が成立する期間では、端子ＳがＨで、かつ端子ＡがＬの出力状態となる。このとき、電流は端子Ｓから端子Ａの方向に流れる。この期間に流れる通電量ｉ１は、端子Ｓから端子Ａに流れる向きを正として、下式で表される。

next,

In the period in which the above is established, the terminal S is in the H output state and the terminal A is in the L output state. At this time, current flows from the terminal S to the terminal A. The energization amount i1 flowing during this period is expressed by the following equation, with the direction flowing from the terminal S to the terminal A being positive.

が成立する期間においては、両端子ともＬを出力するため、電流は流れない。 Also,

In the period in which the above is established, since both terminals output L, no current flows.

が成立する期間においては、端子ＳがＨで、かつ端子ＡがＬの出力状態となるため、電流が流れる。この期間の通電量ｉ２は、下式で表される。

And

In the period in which the condition is established, the terminal S is in the H output state and the terminal A is in the L output state, so that a current flows. The energization amount i2 during this period is expressed by the following equation.

が成立する期間においては、両端子はＬ出力であるため電流は流れない。 Finally,

During the period in which no is satisfied, no current flows because both terminals are at L output.

特に、Ｄｕｔｙ（Ａ）＝０であるとき、単位時間当たりの通電量ｉは最大値ｉＭ、つまり、

である。 From the above, the energization amount i flowing during the period Ta is the sum of i1 and i2, and is given by the following equation.

In particular, when Duty (A) = 0, the energization amount i per unit time is the maximum value iM, that is,

It is.

が成立する期間において、端子Ｓ，Ａの出力は共にＨであるため電流は流れない。 (2) When 25% ≦ Duty (A) ≦ 50% For time t

In the period in which 成立 holds, no current flows because the outputs of terminals S and A are both H.

が成立する期間において、端子ＡがＨで、かつ端子ＳがＬの出力状態となる。このとき、電流は端子Ａから端子Ｓの方向に流れる。この期間に流れる通電量ｉ１は、下式で表される。

next,

In a period in which is established, the terminal A is in the H output state and the terminal S is in the L output state. At this time, current flows from the terminal A to the terminal S. The energization amount i1 flowing during this period is expressed by the following equation.

が成立する期間において、端子Ｓ、Ａの出力は共にＬであるので、両端子間に電流は流れない。 Also,

Since the outputs of the terminals S and A are both L during the period in which is established, no current flows between both terminals.

が成立する期間においては、端子ＳがＨで、かつ端子ＡがＬの出力状態となるため、この期間に流れる通電量ｉ２は、下式で表される。

And

Since the terminal S is in the H output state and the terminal A is in the L output state during the period in which is established, the energization amount i2 flowing during this period is expressed by the following equation.

が成立する期間においては、両端子の出力は共にＬであるため電流は流れない。 Finally,

In the period in which is established, no current flows because the outputs at both terminals are both L.

特に、Ｄｕｔｙ（Ａ）＝５０％の場合、通電量ｉは最小値ｉｍ（＝０）となる。 From the above, the energization amount i flowing during the period Ta is the sum of i1 and i2, and is given by the following equation.

In particular, when Duty (A) = 50%, the energization amount i becomes the minimum value im (= 0).

が成立する期間において、端子Ｓ，Ａの出力は共にＨであるため電流は流れない。 (3) When 50% ≦ Duty (A) ≦ 75% For time t

In the period in which 成立 holds, no current flows because the outputs of terminals S and A are both H.

が成立する期間において、端子ＡがＨで、かつ端子ＳがＬの出力状態となる。このとき、電流は端子Ａから端子Ｓの方向に流れる。この期間に流れる通電量ｉ１は、下式で表される。

next,

In a period in which is established, the terminal A is in the H output state and the terminal S is in the L output state. At this time, current flows from the terminal A to the terminal S. The energization amount i1 flowing during this period is expressed by the following equation.

が成立する期間において、端子Ｓ，Ａの出力は共にＨであるため電流は流れない。
そして、

が成立する期間においては、端子ＳがＨで、かつ端子ＡがＬの出力状態となるため電流が流れる。この期間に流れる通電量ｉ２は、下式で表される。

Also,

In the period in which 成立 holds, no current flows because the outputs of terminals S and A are both H.
And

In the period in which the condition is established, since the terminal S is in the H output state and the terminal A is in the L output state, a current flows. The energization amount i2 flowing during this period is expressed by the following equation.

が成立する期間においては、両端子の出力は共にＬであるため電流は流れない。 Finally,

In the period in which is established, no current flows because the outputs at both terminals are both L.

From the above, the energization amount i flowing during the period Ta is the sum of i1 and i2, and is given by the following equation.

が成立する期間において、端子Ｓ，Ａの出力は共にＨであるため電流は流れない。 (4) When 75% ≦ Duty (A) ≦ 100% For time t

In the period in which 成立 holds, no current flows because the outputs of terminals S and A are both H.

が成立する期間において、端子ＡがＨで、かつ端子ＳがＬの出力状態となる。このとき、電流は端子Ａから端子Ｓの方向に流れる。この期間に流れる通電量ｉ１は、下式で表される。

next,

In a period in which is established, the terminal A is in the H output state and the terminal S is in the L output state. At this time, current flows from the terminal A to the terminal S. The energization amount i1 flowing during this period is expressed by the following equation.

が成立する期間において、端子Ｓ，Ａの出力は共にＨであるため電流は流れない。 Also,

In the period in which 成立 holds, no current flows because the outputs of terminals S and A are both H.

が成立する期間においては、端子ＳがＨで、かつ端子ＡがＬの出力状態となるため電流が流れる。この期間に流れる通電量ｉ２は、下式になる。

And

In the period in which the condition is established, since the terminal S is in the H output state and the terminal A is in the L output state, a current flows. The energization amount i2 flowing during this period is expressed by the following equation.

が成立する期間においては、両端子の出力は共にＬであるため電流は流れない。 Finally,

In the period in which is established, no current flows because the outputs at both terminals are both L.

From the above, the energization amount i flowing during the period Ta is the sum of i1 and i2, and is given by the following equation.

  From (1) to (4) above, by controlling the duty ratio of the output of the terminal A, the energization direction and the energization amount in the period Ta can be controlled. In FIG. 1, the energization control has been described by taking the output waveform of the terminal A as an example. However, the same energization control is performed on the terminal B, and thus the description thereof is omitted.

By applying the energization method to each of the two coils La101 and Lb102, microstep driving can be realized. Table 1 shows the energization amounts and the duty ratios of the terminal A and the terminal B at the time of microstep driving of 32 divisions with one electrical angle.

The energization control method described above is hereinafter referred to as “second energization method”. In the present embodiment, the control method of each output of the terminal A and the terminal B at the time of micro division driving of 32 divisions is shown. Not limited to this, microstep driving with a larger number of steps can be realized by changing the duty ratio with a finer width. The same applies to the embodiments described later.
According to the present embodiment, the current control in the energization period and the short period is not performed in one direction as in the prior art, but the energization control in the forward direction and the reverse direction is adopted, so that the vicinity of the zero cross point is achieved. Current distortion can be reduced. That is, since the forward and reverse energization of the terminals A and B is performed with two periods of the output of the S terminal as one partition, the linearity is made closer to the straight line shown by the graph line L in the duty ratio-current characteristic of FIG. It can be secured.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals as those used in the first embodiment, and detailed description thereof will be omitted, and differences will be described. Omitting such description is the same in the embodiments described later.
FIG. 2 is a waveform diagram for explaining energization control in the present embodiment. In this case, it is assumed that the output period Ta of the coil-side terminal A is ½ times the output period Ts of the common terminal S and is synchronized. That is, “2 × Ta = Ts” is established. From the output cycle Ts of the terminal S and the duty ratio Duty (A) of the output of the terminal A, the energization amount i at the time Ts (2 cycles) is expressed by the following equation.

By applying the energization method to each of the two coils La101 and Lb102, microstep driving can be realized. The duty ratios and energization amounts of the terminals A and B at the time of the microstep drive of 32 divisions with one electrical angle in the energization method are the same as in Table 1. Hereinafter, this energization control method is referred to as a “third energization method”.
According to the present embodiment, the period of the first and third pulse width modulation signals is set to one half of the period of the second pulse width modulation signal, and the duty ratio of the outputs of the terminals A and B is controlled. The current distortion in the vicinity of the zero cross point can be reduced.

[Third Embodiment]
Next, a third embodiment of the present invention will be described.
FIG. 3 is a waveform diagram for explaining energization control in the present embodiment. In this embodiment, each output of the terminal S and the terminal A has the same cycle, and the energization amount is controlled by delaying the duty ratio and the timing of the rise time and the fall time.
Regarding the energization control, the duty ratio of the output of the terminal A is set to Duty (A), and the potential in the initial state of the terminal A is set to L. Assume that the rising timing is delayed by a delay rate a% with respect to the cycle T (= Ts = Ta). The delay rate represents the ratio of the delay time to the period T.

これより、時間Ｔａの間に端子ＳからＡの方向に流れる電流ｉ１は、下式となる。

端子Ａから端子Ｓの方向に流れる電流ｉ２は、下式となる。

The control circuit 130 performs energization control so that the following relationship is satisfied.

Thus, the current i1 flowing in the direction from the terminal S to A during the time Ta is expressed by the following equation.

A current i2 flowing from the terminal A to the terminal S is expressed by the following equation.

上記通電制御方式を、以下、「第４の通電方式」という。なお、本実施形態では端子Ａの初期状態の電位をＬとしたが、端子Ａの初期状態の電位をＨとし、周期Ｔに対して立下り時点のタイミングをａ％遅らせることで同様の駆動を行っても構わない。 Therefore, the energization amount flowing between the terminal S and the terminal A is the sum of i1 and i2, and is given by the following equation.

Hereinafter, the energization control method is referred to as a “fourth energization method”. In this embodiment, the initial state potential of the terminal A is set to L, but the initial state potential of the terminal A is set to H, and the same driving is performed by delaying the timing at the falling time by a% with respect to the period T. You can go.

By applying the energization method to each of the two coils La101 and Lb102, microstep driving can be realized. Table 2 shows the respective energization amounts, duty ratios, and delay rates of the terminals A and B at the time of microstep driving of 32 divisions with one round of electrical angle in the above energization method.

  In this embodiment, the delay rate is set with respect to the rise or fall timing of the drive signal output from the second HB circuit, and the switching timing and the duty ratio of the drive signal are controlled respectively. Thereby, the current distortion in the vicinity of the zero cross point can be reduced.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. FIG. 5 shows a system configuration example of the imaging apparatus 1 according to the present embodiment.
The optical block 10 constituting the imaging optical system of the imaging apparatus 1 includes movable members such as a magnification lens 11a, a focus adjustment lens 11b, a diaphragm 12, a shutter 13, and the like. The magnification lens 11a is a movable lens group that moves in the optical axis direction when performing zoom driving. The focus adjustment lens 11b is a movable lens group (focus lens) that moves in the optical axis direction during focus adjustment. The aperture 12 and the shutter 13 are optical devices that are driven during light amount control.

The control block 30 of the lens driving unit is a control means for driving each constituent member in the optical block 10. The zoom control unit 31 performs drive control of the magnification lens 11a to change the focal length of the imaging optical system. The focus control unit 32 performs drive control of the focus adjustment lens 11b. The aperture control unit 33 controls the aperture diameter of the aperture 12, and the shutter control unit 34 controls the drive of the shutter 13. Each control unit includes an actuator that drives the movable optical element, an HB circuit, and the like.
The image sensor 21 photoelectrically converts an optical image formed by the optical block 10 into an electrical signal. The imaging control unit 22 controls the drive timing of the imaging element 21 and the like. The A / D converter 23 converts the analog signal output from the image sensor 21 into a digital signal. The digital signal is stored in the internal memory 43 via the image input unit 24 and processed by the memory control circuit 41 and the system controller 8. The image processing unit 25 performs predetermined pixel interpolation processing and color conversion processing on the data after conversion by the A / D converter 23 or the data from the memory control circuit 41.

  The memory control circuit 41 controls the A / D converter 23, the image processing unit 25, the compression / decompression circuit 42, and the internal memory 43, and controls the data recording operation on the recording medium 44. The image display control unit 27 performs display control of the image display unit 6. The image display unit 6 includes a display device such as a TFT (Thin Film Transistor) LCD (Liquid Crystal Panel). The display image data written in the internal memory 43 is sent to the image display unit 6 via the image display control unit 27 and displayed. The internal memory 43 stores captured still image and moving image data, and is also used as a work area for the system controller 8. The compression / decompression circuit 42 reads the image data stored in the internal memory 43, executes compression processing or decompression processing, and performs processing of writing the processed data in the internal memory 43 again.

  The system controller 8 includes a CPU (Central Processing Unit) and controls the entire imaging apparatus 1. The CPU reads out a predetermined program from the memory and executes it, thereby controlling the operation of each unit such as the lens driving unit. The common terminal output control unit 60 that controls the control block 30 of the lens driving unit is controlled by a signal output from the system controller 8. The common terminal output control unit 60 controls the output of the common terminal S described in the first embodiment (having the function of the control unit 115 in FIG. 1).

The operation unit used by the user for operation instructions includes, for example, a power switch 2, a release switch 3, a zoom operation switch 4, and a menu operation switch 5. The operation unit is an operation unit for inputting various operation instructions to the system controller 8 and includes a switch, a dial, a touch panel, and the like. The release switch 3 outputs a trigger signal for operating a shutter to record a still image and a trigger signal for starting and stopping moving image recording. For example, the release switch 3 includes a first switch (SW1) that outputs a signal for a shooting preparation instruction by a first stroke (half-press) operation of the release button. The release switch 3 further includes a second switch (SW2) that outputs a signal for starting a photographing operation by a second stroke (full press) operation. When the user operates the zoom operation switch 4, the drive control of the optical block 10 is performed according to the operation instruction, and the focal length of the imaging optical system is changed.
The power control unit 46 performs control to supply power from the power source 47 to the imaging apparatus 1 using an operation signal of the power switch 2 as a trigger.

  In the present embodiment, in the image pickup apparatus 1, a stepping motor is used for a focus adjustment lens which is a movable member and a driving unit for an iris diaphragm, and control is performed by any one of the second to fourth energization methods. For the zoom control, shutter control, and ND filter, the first energization method with less power loss at zero crossing is applied. According to the present embodiment, in the drive control of the focus lens and the iris diaphragm, the microstep drive is performed by adopting any of the second to fourth energization methods having excellent duty ratio-current characteristics in the vicinity of the zero cross point. Smooth drive control can be realized.

[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described. Note that the configuration of the imaging apparatus according to the present embodiment is the same as that of the fourth embodiment, and therefore only the differences will be described below.
In the microstep drive of the focus adjustment lens or the iris diaphragm in the imaging apparatus 1, any one of the second to fourth energization methods is applied in the moving image shooting mode. In the still image shooting mode (stop accuracy priority), the first energization method with less power loss at the time of zero crossing is applied. Thereby, it is possible to reduce the noise when the motor is driven during moving image recording. On the other hand, when recording a still image, the motor stop accuracy can be increased by adopting the first energization method with low power loss and high resolution at the time of zero crossing.

DESCRIPTION OF SYMBOLS 1 Imaging device 8 System controller 11b Focus adjustment lens 13 Diaphragm 21 Imaging element 32 Focus control part 33 Aperture control part 100 Two-phase stepping motor 110A, 110B, 110S Periodic signal generation part 115 Control part 120A, 120B, 120S HB circuit

Claims (12)

A first half-bridge circuit having a first output terminal connected to the actuator;
A second half bridge circuit having a second output terminal connected to the actuator;
A first periodic signal generator for outputting a drive signal by pulse width modulation from the first half-bridge circuit;
A second periodic signal generator for outputting a drive signal by pulse width modulation from the second half-bridge circuit;
The period of the first pulse width modulation signal by the first period signal generator and the period of the second pulse width modulation signal by the second period signal generator are set to different periods, and the first half bridge circuit outputs An actuator driving device comprising a control unit that changes a duty ratio of a driving signal.   2. The actuator driving apparatus according to claim 1, wherein the control unit sets the cycle of the first pulse width modulation signal to twice the cycle of the second pulse width modulation signal.   2. The actuator driving apparatus according to claim 1, wherein the control unit sets a cycle of the first pulse width modulation signal to one half of a cycle of the second pulse width modulation signal. A first half-bridge circuit having a first output terminal connected to the actuator;
A second half bridge circuit having a second output terminal connected to the actuator;
A first periodic signal generator for outputting a drive signal by pulse width modulation from the first half-bridge circuit;
A second periodic signal generator for outputting a drive signal by pulse width modulation from the second half-bridge circuit;
The first pulse width modulation signal by the first period signal generator and the second pulse width modulation signal by the second period signal generator are set to the same period, and the first half bridge is connected to the second half bridge circuit. An actuator driving device comprising: a control unit that changes a switching timing of a circuit and a duty ratio of a driving signal.   The control unit sets a delay rate with respect to the rise or fall timing of the drive signal output from the second half bridge circuit, and sets the rise or fall of the drive signal output from the first half bridge circuit. The actuator driving apparatus according to claim 4, wherein the timing is changed.   6. The actuator driving apparatus according to claim 1, wherein the control unit sets a duty ratio of a driving signal output from the second half bridge circuit to a constant value. 7. The actuator driving device according to any one of claims 1 to 6, comprising:
An imaging apparatus characterized in that a movable member constituting an imaging optical system is driven by the actuator. The actuator is a stepping motor;
The imaging apparatus according to claim 7, wherein the actuator driving device drives a focus adjustment lens or an iris diaphragm by microstep driving. A first half-bridge circuit having a first output terminal connected to the actuator;
A second half bridge circuit having a second output terminal connected to the actuator;
A first periodic signal generator for outputting a drive signal by pulse width modulation from the first half-bridge circuit;
A second periodic signal generator for outputting a drive signal by pulse width modulation from the second half-bridge circuit;
A control method executed by an actuator driving device including a controller that controls the first periodic signal generator and the second periodic signal generator,
The control unit sets the cycle of the first pulse width modulation signal by the first cycle signal generation unit and the cycle of the second pulse width modulation signal by the second cycle signal generation unit to different cycles; 1. A method for controlling an actuator drive device, comprising: changing a duty ratio of a drive signal output from one half-bridge circuit. A first half-bridge circuit having a first output terminal connected to the actuator;
A second half bridge circuit having a second output terminal connected to the actuator;
A first periodic signal generator for outputting a drive signal by pulse width modulation from the first half-bridge circuit;
A second periodic signal generator for outputting a drive signal by pulse width modulation from the second half-bridge circuit;
A control method executed by an actuator driving device including a controller that controls the first periodic signal generator and the second periodic signal generator,
The control unit sets the first pulse width modulation signal by the first periodic signal generation unit and the second pulse width modulation signal by the second periodic signal generation unit to the same period, and the second half bridge circuit On the other hand, the actuator driving device control method includes a step of changing a switching timing of the first half-bridge circuit and a duty ratio of the driving signal. A control method executed by an imaging apparatus that drives a movable member constituting an imaging optical system by an actuator,
11. The control method for an image pickup apparatus according to claim 9, wherein the control unit performs drive control of a focus adjustment lens or an iris diaphragm according to the control method for an actuator drive apparatus according to claim 9.   12. The method of controlling an imaging apparatus according to claim 11, wherein in the moving image shooting mode, the control unit performs drive control of the focus adjustment lens or the iris diaphragm by microstep driving.

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