JP2015015823A - Actuator driving device, method for controlling the same, and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the amount of a current which can be supplied to a desired actuator when a plurality of actuators are driven simultaneously.SOLUTION: A motor driving device that drives motors 1 and 2 simultaneously changes the duty ratio of the output of a common terminal S according to a necessary amount of current. Duty ratio setting units 106A, 106B, and 106S set the duty ratios of outputs of half-bridge circuits 103A, 103B, and 103S according to a control signal from a current amount control unit 105. The amount of the current which can be supplied to the motor is increased as the duty ratio of the output of the half-bridge circuit connected to a terminal A or B decreases in control for causing a current to flow in a direction from the common terminal S toward the terminal A or B. The duty ratio of the output of the half-bridge circuit 103S is made small and the duty ratio of the output of the half-bridge circuit 103A or 103B is made large so as to increase the amount of the current which can be supplied to the motor in control for causing a current to flow in the direction from the terminal A or B toward the common terminal S.

Description

  The present invention relates to a technique for controlling a current supply amount to an actuator in an actuator driving device capable of energizing a plurality of actuators simultaneously.

2. Description of the Related Art A bipolar motor drive device using PWM (pulse width modulation) control for the purpose of cost reduction includes a plurality of half-bridge circuits (hereinafter also referred to as HB circuits). One HB circuit is used by connecting one of the plurality of motor terminals as a power source for supplying current to the motor, and the remaining HB circuit is connected to the other motor terminal.
In the device disclosed in Patent Literature 1, the duty ratio of the output of the HB circuit used as a power source, that is, the output of the common terminal is fixed to 50%. By setting an arbitrary duty ratio for the output of the HB circuit on the coil side of the motor, an on period in which a current is generated by generating a potential difference and a short period in which no current flows due to an equipotential are generated, and the current direction and energization The amount is determined.

  FIG. 6A is a block diagram showing a configuration of a conventional two-phase stepping motor driving apparatus using bipolar driving. The two-phase stepping motor 600 includes an A-phase coil La601, a B-phase coil Lb602, and a magnetized rotor 603. The output terminals of the HB circuits 604A, 604S and 604B are connected to the terminals A, S and B, respectively. The terminal S is a common terminal that connects the A-phase coil La601 and the B-phase coil Lb602. The HB circuit 604A can select a state in which current is absorbed by an input signal to the input terminals in1 and in2, a state in which current is supplied, and an open state in which no current flows. The control circuit 605 controls the HB circuits 604A, 604S, and 604B. The control circuit 605 selects the state of the HB circuit 604A based on signals from the terminals Vpa and Vna, and controls the driving of the stepping motor 600. Similarly, the HB circuit 604B is controlled by signals from the terminals Vpb and Vnb of the control circuit 605, and the HB circuit 604S is controlled by signals from the terminals Vps and Vns of the control circuit 605. FIG. 6B is a circuit diagram illustrating a configuration of the HB circuits 604A, 604B, and 604S. Each circuit includes a Pch (channel) FET element 611 and an NchFET element 612, and the Pch driver 613 drives the PchFET element 611 and the Nch driver 614 drives the NchFET element 612.

  The motor energization method will be described with reference to FIG. The HB circuit 604S is set to an output signal with a duty ratio of 50%. On the other hand, the HB circuits 604A and 604B on the coil side synchronize with the HB circuit 604S and control each output. When the duty ratios of the terminal A of the HB circuit 604A and the terminal B of the HB circuit 604B are Da% and Db%, respectively, the energization amount is is “energization amount isa = (50−Da) × Im / 100 ". For 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 level, that is, when a motor drive voltage is output, the common terminal S functions as a power source for supplying current. During this period, when the terminal A becomes L level, that is, the ground potential, the current flows from the common terminal S to the terminal A through the A-phase coil La601. 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 to the common terminal S through the coil La601. 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. This energization control is not limited to driving a stepping motor, and can be applied even when various actuators are provided.

JP 2004-15898 A

However, in the conventional drive control, the duty ratio of the common terminal S is fixed to 50%. For this reason, there is a problem that the maximum amount of current that can be supplied to the motor becomes 50% when the motor drive voltage is used in the full bridge circuit (see A: Duty 0% shown in FIG. 7).
An object of the present invention is to control the amount of current that can be supplied to a desired actuator when simultaneously driving a plurality of actuators.

  In order to solve the above problems, an apparatus according to the present invention is an actuator driving apparatus that drives a plurality of actuators, and includes a first half-bridge circuit having a first output terminal to which the first actuator is connected, and a second A second half bridge circuit having a second output terminal to which the actuator is connected, a third half bridge circuit having a third output terminal to which the first actuator and the second actuator are connected, and the first half bridge circuit outputting A first duty ratio setting unit that sets a first duty ratio related to the driving voltage to be performed; a second duty ratio setting unit that sets a second duty ratio related to the driving voltage output by the second half bridge circuit; A third duty ratio setting unit for setting a third duty ratio related to the drive voltage output by the three half bridge circuit; Comprising a current control section for outputting a serial first actuator and the control signal determines the amount of current supplied to the second actuator to the first to third duty ratio setting unit. The current amount control unit outputs a control signal for changing the third duty ratio according to the amount of current supplied to the first actuator or the second actuator when the first actuator and the second actuator are driven simultaneously. Output to the ratio setting section.

  According to the present invention, when a plurality of actuators are driven simultaneously, the amount of current that can be supplied to a desired actuator can be controlled.

It is a block diagram which shows the structural example of the actuator drive device which concerns on 1st Embodiment of this invention. FIG. 2 is a waveform diagram illustrating terminal voltages in the actuator driving device of FIG. 1. 1 is a diagram illustrating a system configuration example of an imaging apparatus according to an embodiment of the present invention. It is a flowchart explaining the drive control which concerns on 2nd Embodiment of this invention. It is a flowchart explaining the drive control which concerns on 3rd Embodiment of this invention. It is a block diagram which shows the structure of the conventional motor drive device and a half bridge circuit. It is a wave form diagram which shows each terminal voltage in the motor drive device of FIG.

Hereinafter, each embodiment of the present invention will be described.
[First Embodiment]
A first embodiment of the present invention will be described. In the first embodiment, an actuator driving apparatus that drives a plurality of motors as an actuator will be described as an example. However, the present invention is not limited to a motor and can be applied to driving various actuators.

  FIG. 1 is a block diagram illustrating a configuration example of a motor drive device according to the first embodiment. The motor drive device can drive two motors simultaneously. A motor 1 (first motor) that is a first actuator has a coil 101, and a motor 2 (second motor) that is a second actuator has a coil 102. The half bridge circuits 103A, 103S, and 103B have the configuration shown in FIG. 6B and are connected to the terminal A, the terminal S, and the terminal B, respectively. The terminal S is a common terminal S to which the coil 101 and the coil 102 are connected. Hereinafter, the first half bridge circuit having the first output terminal A to which the first motor is connected is referred to as a first HB circuit. The second half bridge circuit having the second output terminal B to which the second motor is connected is referred to as a second HB circuit. A third half bridge circuit having a third output terminal S to which the first motor and the second motor are connected is referred to as a third HB circuit.

  The first HB circuit 103A can select a state of sucking current, a state of supplying current, and an open state in which no current flows according to input signals to the input terminals in1 and in2. The control unit 104 that controls the first HB circuit 103A, the second HB circuit 103B, and the third HB circuit 103S includes a current amount control unit 105, a first duty ratio setting unit 106A, a second duty ratio setting unit 106B, and a third duty ratio setting unit. 106S is provided. The first duty ratio setting unit 106A is connected to the first HB circuit 103A and sets the first duty ratio of the output voltage of the first HB circuit 103A. The second duty ratio setting unit 106B is connected to the second HB circuit 103B and sets the second duty ratio of the output voltage of the second HB circuit 103B. The third duty ratio setting unit 106S is connected to the third HB circuit 103S and sets the third duty ratio of the output voltage of the third HB circuit 103S.

  In the control unit 104, the current amount control unit 105 determines the amount of current to be supplied to the motor 1 and the motor 2, and outputs a control signal to the first to third duty ratio setting units. That is, the signals of the terminals Vpx and Vnx of each duty ratio setting unit are determined by the amount of current determined by the current amount control unit 105 (x is one of a, b, and s). For example, the driving state of the first HB circuit 103A is selected by controlling signals from the terminals Vpa and Vna, and the driving voltage is applied to the coil 101. Similarly, the driving state of the second HB circuit 103B is selected according to signals from the terminals Vpb and Vnb, and a driving voltage is applied to the coil 102. The driving state of the third HB circuit 103S is selected according to signals from the terminals Vps and Vns, and a voltage is applied to the coils 101 and 102. In this way, control of the motor 1 and the motor 2 is executed.

Each terminal voltage in this embodiment is shown in FIG. FIG. 2A illustrates waveforms of the voltage at the common terminal S, the voltage at the terminal A (see Act_A), and the voltage at the terminal B (see Act_B). The shaded portion in FIG. 2 corresponds to the energization amount, and the downward arrow corresponds to the direction of current flowing from the common terminal S toward the terminal A or B.
The duty ratio related to the output of the common terminal S is Duty (S), the duty ratio related to the output of the terminal A on the motor 1 side is Duty (A), and the duty ratio related to the output of the terminal B on the motor 2 side is Duty ( B). The amount of current flowing when the output state of the common terminal S is always at the H level during one cycle and the output state of the terminal A or B is always at the L level during the synchronization is denoted as Im.
The amount of current iL101 flowing through the coil 101 is expressed by the following equation, where the first direction flowing from the common terminal S to the terminal A is positive.

[Formula 1]
iL101 = (Duty (S) −Duty (A)) × Im / 100
Similarly, the amount of current iL102 flowing through the coil 102 is expressed by the following equation when the second direction flowing from the common terminal S to the terminal B is corrected.
[Formula 2]
iL102 = (Duty (S) −Duty (B)) × Im / 100
Hereinafter, the drive for energizing using the region where the voltage level is H at the output of the common terminal S is referred to as “first drive”.

  As can be seen from [Equation 1] and [Equation 2], in the first drive, if the difference between Duty (S) and Duty (A) and the difference between Duty (S) and Duty (B) are increased, The amount of current in each coil can be increased. That is, by increasing the duty ratio related to the output of the common terminal S and bringing the duty ratios of the output terminals A and B of the HB circuit on the coils 101 and 102 side closer to 0%, the amount of current flowing in the coils 101 and 102 is reduced. To increase. However, the direction in which a large current can flow is limited to the first direction from the common terminal S to the output terminal A of the HB circuit on each motor side or the second direction to the output terminal B. When driving the motors 1 and 2 at the same time, the third duty ratio setting unit 106S increases the third duty ratio by a control signal from the current amount control unit 105, so that the direction from the common terminal S to the output terminal A or B is increased. To control the current flowing through

As for the output terminal A or B of each HB circuit, when the period of the output of the common terminal S is T and the period in which the output of the common terminal S is L level is T1, the time “T−2 · Tl” It can be energized in both directions between time T. For example, when the duty ratio related to the output of the terminal A or the terminal B is 80%, the upper limit of the energization amount is reduced to 20%, but the energization is possible in an arbitrary direction. In the following, the drive for energizing using the region where the voltage level is L at the output of the common terminal S will be referred to as “second drive”.
By using the two drive patterns of the first drive and the second drive described above, the two motors can be energized simultaneously. That is, in the first motor, it is possible to flow a large current only in the energization direction from the common terminal S to the output terminal A or B of each HB circuit on the motor side, and in the second motor, the energization direction is small in an arbitrary energization direction. Current can flow.

Such drive control is not limited to simultaneous energization of two motors, but can be implemented with a configuration in which three or more motors are connected. However, it is not possible to freely change the energization amount for a plurality of motors. That is, it is necessary to group a plurality of motors into the following two types.
A first motor group that causes a current to flow from the common terminal S to the output terminal of each motor at a desired current amount of Duty (S) × Im or less.
A second motor group that allows current to flow in both directions between the common terminal S and the output terminals of each motor at a desired current amount of 50 × (1-Duty (S)) × Im or less.
According to the energization control described above, it is possible to flow a predetermined amount of current from the common terminal S to the terminal B (or terminal A) while increasing the amount of current flowing from the common terminal S to the terminal A (or terminal B).

Next, energization control for flowing a predetermined amount of current from the common terminal S to the terminal B (or terminal A) while increasing the amount of current flowing from the terminal A (or terminal B) to the common terminal S will be described.
FIG. 2B illustrates waveforms of the voltage at the common terminal S, the voltage at the terminal A (see Act_A), and the voltage at the terminal B (see Act_B). The hatched portion in FIG. 2 corresponds to the energization amount, and the downward arrow corresponds to the direction of current flowing from the common terminal S to the terminal A. The upward arrow corresponds to the direction of current flowing from the terminal B toward the common terminal S.

  When driving a plurality of actuators simultaneously, the third duty ratio setting unit 106S decreases the third duty ratio by a control signal from the current amount control unit 105 and moves from the output terminal A or B to the common terminal S. Control the flowing current. In the example shown in FIG. 2B, the second duty ratio setting unit 106 </ b> B increases the second duty ratio by a control signal from the current amount control unit 105, so that the current flowing from the terminal B to the common terminal S Increase. On the other hand, the first duty ratio setting unit 106A determines the amount of current flowing from the common terminal S to the terminal A by setting the first duty ratio.

  In the present embodiment, when the first and second actuators are driven simultaneously, a control signal for changing the third duty ratio by the current amount control unit 105 according to the amount of current supplied to each actuator is sent to the third duty ratio setting unit. Output. By controlling the duty ratio related to the voltage of the common terminal, it is possible to increase the amount of current that can be supplied to a desired actuator when a plurality of actuators are energized simultaneously. Specifically, as shown in FIG. 2 (A), the third duty ratio is changed and set to 50% or more and less than 100%, and the first duty ratio or the second duty ratio is decreased to reduce the common duty ratio. The current flowing in the direction from the terminal S to the terminal A or B can be increased. Further, as shown in FIG. 2B, by changing the third duty ratio to be set to 0% or more and less than 50% and increasing the first duty ratio or the second duty ratio, the terminal A or B The current flowing in the direction of the common terminal can be increased.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. FIG. 3 shows a system configuration example of the imaging apparatus 1 according to the present embodiment.
The optical block 10 constituting the image pickup optical system of the image pickup apparatus 1 includes 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 diaphragm 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, a half-bridge 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 of 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 controls the operation of each unit by reading a predetermined program from the memory and executing it. The common terminal output control unit 60 in 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 (that is, has a function of the control unit 104 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 following, in the imaging apparatus 1 shown in FIG. 3, a case will be described in which the first drive is performed when the shutter 13 is closed, and the focus position holding current is simultaneously performed by the second drive. The shutter control unit 34 controls the opening / closing operation of the shutter by the first actuator driven by the actuator driving device described in the first embodiment. In addition, the focus control unit 32 performs focus driving of the imaging optical system by the second actuator driven by the actuator driving device described in the first embodiment. In the present embodiment, it is possible to realize the same drive as the shutter operation in the full bridge circuit without increasing the drive voltage of the actuator.

FIG. 4 is a flowchart for explaining the operation of each unit in this embodiment.
First, in S401, the common terminal output control unit 60 sets the duty ratio related to the output voltage of the common terminal S to 50%. In step S402, energization for holding the focus position is started. The focus position related to the focus adjustment control corresponds to the position on the optical axis of the focus adjustment lens 11b, and the position is determined by holding energization. Thereafter, in S403, the system controller 8 determines whether or not the first switch SW1 is turned on by the half-press operation of the release switch 3. If SW1 is in the on state (S403: ON), the process proceeds to S404. If SW1 is in the off state (S403: OFF), the process returns to S401.

In S404, the system controller 8 performs a focusing process based on the focus detection of the imaging optical system, and the focus control unit 32 executes a focus adjustment operation by driving control of the focus adjustment lens 11b. As for focus detection, detection methods such as a phase difference detection method, a contrast detection method, or a method using both methods are known, and detailed description thereof will be omitted.
After completion of the focusing process in S404, the process proceeds to S405, and the common terminal output control unit 60 changes the duty ratio related to the output voltage of the common terminal S to 80%. Thereafter, in S406, the common terminal output control unit 60 starts energization of the focus position and fixes the focus position. Here, the current required only for holding energization may be small. In the present embodiment, by changing the duty ratio between 60% and 100%, a desired energization amount can be obtained within a range of ± 20%.

  With the focus position determined in S406, the system controller 8 determines the operating state of the release switch 3 in S407. If SW1 remains in the on state (S407: SW1), the process returns to S406 and the energization for holding the focus position continues. If the release switch 3 is fully pressed and the second switch SW2 is on (S407: SW2), the process proceeds to S408. In S408, the shutter control unit 34 closes the shutter 13. Although a large amount of current is required for driving the shutter, the duty of the common terminal S is changed to 80% in S405. Therefore, the amount of current that can be supplied at this time has increased to 80% of Im. Although the amount of current that can be supplied from the common terminal S is increasing, the closing direction of the shutter 13 in order to obtain a desired amount of current is such that it flows from the common terminal S to the output terminal of the HB circuit of the shutter control unit 34. It is necessary to set the current amount. Further, in order to flow the maximum current, the duty ratio of the HB circuit in the shutter control unit 34 may be as small as possible, that is, 0%. This is shown in FIG. In the present embodiment, “Act_A” represents the drive voltage of the actuator of the focus adjustment lens 11b, and “Act_B” represents the drive voltage of the actuator of the shutter 13.

In S407, when both SW1 and SW2 of the release switch 3 are in the off state (S407: OFF), the process returns to S401.
In S409 after the shutter 13 is closed in S408, the system controller 8 controls processing of the captured image and image data recording processing. The image data after exposure is processed by the image processing unit 25, and writing processing to the recording medium 44 is executed. Proceeding to next step S410, the common terminal output control unit 60 changes the duty ratio related to the output voltage of the common terminal S to 20%. In S411, the shutter control unit 34 opens the shutter 13. Each terminal voltage at this time is shown in FIG. “Act_A” and “Act_B” are as described with reference to FIG. When the shutter 13 is opened, a large amount of current is required as in the case where the shutter 13 is closed, but the direction of the current is reversed. As shown in Act_B, in order to flow the maximum current to the shutter 13, the duty ratio of the HB circuit in the shutter control unit 34 may be increased as much as possible, for example, set to 100%. Further, since the holding energization at the focus position continues even when the shutter 13 is opened, by changing the duty ratio for holding energization between 0% and 40%, for example, as shown by Act_A, ± 20 A desired energization amount can be obtained in the range of%.

After the shutter 13 is opened in S411, the process proceeds to S412, and the common terminal output control unit 60 performs setting to return the duty ratio related to the output voltage of the common terminal S to 50%, and a series of shutter driving ends.
According to the present embodiment, the amount of current that can be supplied to the actuator can be increased by changing the third duty ratio when the shutter is opened and closed by the actuator driving device. For example, the energization control of the actuator is performed by the first drive during the closing operation of the shutter. In other driving operations, the third duty ratio is set to 50%, and the shutter driving actuator is energized.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. In the third embodiment, the same components as those in the first and second embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted. Differences will be mainly described.
In the present embodiment, when the focal length of the imaging optical system is changed in the imaging apparatus shown in FIG. 3, the actuator driving apparatus drives the actuator by the first driving when the zoom driving starts. At the same time, the energization for holding the focus position is performed by the second drive. The zoom control unit 31 in FIG. 3 drives the magnification lens 11a of the imaging optical system by a zoom driving actuator, and the focus control unit 32 drives the focus adjustment lens 11b of the imaging optical system by a focus driving actuator. And

Hereinafter, with reference to the flowchart of FIG. 5, the extension and retraction operation of the magnification lens 11a during zoom driving will be described.
First, in S501, the common terminal output control unit 60 sets the duty ratio related to the output voltage of the common terminal S to 50%. In step S502, energization for holding the focus position is started. In step S <b> 503, the system controller 8 determines the operation state of the zoom operation switch 4. If the zoom operation switch 4 is not operated (S503: OFF), the process returns to S501. Further, when the zoom operation switch 4 is being operated to the Tele (telephoto end) side (S503: Tele), the process proceeds to S504. When the zoom operation switch 4 is being operated to the Wide (wide-angle end) side (S503: Wide), the process proceeds to S506.

  In step S <b> 504, the system controller 8 determines the energization direction from the operation state of the zoom operation switch 4. When the energization direction is determined, the common terminal output control unit 60 changes the duty ratio related to the output voltage of the common terminal S to 80% accordingly (S505). Note that the direction of current during zoom driving is from the common terminal S to the terminal B (Act_B). That is, since a current flows from the common terminal S to the output terminal of the half bridge circuit of the zoom control unit 31, a direction corresponding to the direction is set as a feeding direction in S504.

  Each terminal voltage by energization after S505 is illustrated in FIG. In this example, “Act_A” represents the driving voltage of the focus driving actuator, and “Act_B” represents the driving voltage of the zoom driving actuator. Since a large amount of current is required when the zoom drive is extended, it is necessary to increase the duty of the common terminal S to 80% and set the duty ratio of Act_B to 0%. A large amount of current can be secured. In this case, the energization of the focus position is continued, but the required amount of current may be small. Therefore, the duty ratio of Act_A is changed within a range of ± 20% by changing between 60% and 100%. Can be obtained.

  On the other hand, when the zoom operation switch 4 is operated to the Wide side in S503, the process proceeds to S506. Here, the system controller 8 determines the energization direction from the operation state of the zoom operation switch 4. In S507, the common terminal output control unit 60 changes the duty ratio related to the output voltage of the common terminal S to 20% in S507 in accordance with the determined energization direction. The direction of current during zoom driving is the direction from the terminal B (Act_B) to the common terminal S. That is, since a current flows from the output terminal of the half bridge circuit of the zoom control unit 31 toward the common terminal S, a direction corresponding to the direction is set as a retraction direction in S507.

  Each terminal voltage by energization after S507 is illustrated in FIG. The meanings of “Act_A” and “Act_B” are as described above. A large amount of current is required when the zoom drive is started, and the energization direction is opposite to that when the zoom drive is started. Therefore, by reducing the duty ratio related to the output voltage of the common terminal S to 20% and setting the duty ratio of Act_B to 100%, it is possible to secure a necessary amount of current in the energization direction opposite to that during feeding. it can. In this case, the holding energization at the focus position is continued, but the required current may be small. Therefore, by changing the duty ratio of Act_A between 0% and 40%, a desired range of ± 20% can be obtained. The amount of current can be obtained.

After the processes of S505 and S507 are completed, the process proceeds to S508, and the zoom control unit 31 starts the energization described above. In S509, the system controller 8 determines whether or not a predetermined time (initial movement time) has elapsed since the magnification lens 11a started to move. The energization process continues from the time when the magnification lens 11a starts to move until the initial movement time elapses (S509: NO). When the initial time elapses in S509 (S509: YES), the process proceeds to S510, and the common terminal output control unit 60 returns the duty ratio related to the output voltage of the common terminal S to 50%. In the next S511, under the control of the system controller 8, an operation for tracking the focus position in accordance with the zoom drive is performed. This operation is continuously performed while the zoom operation switch 4 is being operated in S512 (S512: NO returns to S511).
If the system controller 8 determines in S512 that the zoom operation switch 4 has been turned off (S512: YES), the system controller 8 proceeds to S513 and performs control to hold the focus position. In S514, the energization control of the zoom control unit 31 ends, and a series of zoom driving ends.
Note that the energization control described above can be applied even when the zoom driving extension direction or the retraction direction is set in reverse.

  According to this embodiment, the amount of current that can be supplied to the actuator can be increased by changing the third duty ratio at the start of zoom driving for changing the focal length of the imaging optical system by the actuator driving device. For example, when the zoom driving starts, the energization control of the actuator is performed by the first driving. In other driving, the third duty ratio is set to 50%, and the zoom driving actuator is energized and controlled.

DESCRIPTION OF SYMBOLS 1 Imaging device 11a Magnification lens 11b Focus adjustment lens 13 Shutter 31 Zoom control part 32 Focus control part 34 Shutter control part 60 Common terminal output control part 101,102 Motor coil 103A, 103B, 103S Half bridge circuit 104 Control part

Claims (10)

An actuator driving device for driving a plurality of actuators,
A first half-bridge circuit having a first output terminal to which a first actuator is connected;
A second half bridge circuit having a second output terminal to which a second actuator is connected;
A third half bridge circuit having a third output terminal to which the first actuator and the second actuator are connected;
A first duty ratio setting unit for setting a first duty ratio related to the drive voltage output by the first half bridge circuit;
A second duty ratio setting unit for setting a second duty ratio related to the drive voltage output by the second half bridge circuit;
A third duty ratio setting unit for setting a third duty ratio related to the drive voltage output by the third half bridge circuit;
A current amount control unit that determines a current amount to be supplied to the first actuator and the second actuator and outputs a control signal to the first to third duty ratio setting units;
The current amount control unit outputs a control signal for changing the third duty ratio according to the amount of current supplied to the first actuator or the second actuator when the first actuator and the second actuator are driven simultaneously. An actuator driving device that outputs to a ratio setting unit.   When driving the first actuator and the second actuator at the same time, the third duty ratio setting unit increases the third duty ratio by the control signal from the current amount control unit and outputs the third duty ratio from the third output terminal. The actuator driving device according to claim 1, wherein a current flowing in the direction of the first output terminal or the second output terminal is controlled.   When simultaneously driving the first actuator and the second actuator, the third duty ratio setting unit reduces the third duty ratio by the control signal from the current amount control unit, and the first output terminal or The actuator driving device according to claim 1, wherein a current flowing from the second output terminal to the third output terminal is controlled.   When driving the first actuator and the second actuator at the same time, the first duty ratio setting unit or the second duty ratio setting unit is configured such that the first duty ratio or the second duty is determined by the control signal from the current amount control unit. 3. The actuator driving device according to claim 2, wherein a current flowing from the third output terminal to the first output terminal or the second output terminal is increased by decreasing the ratio.   When driving the first actuator and the second actuator at the same time, the first duty ratio setting unit or the second duty ratio setting unit is configured such that the first duty ratio or the second duty is determined by the control signal from the current amount control unit. 4. The actuator driving device according to claim 3, wherein a current flowing in the direction from the first output terminal or the second output terminal to the third output terminal is increased by increasing the ratio. The actuator driving device according to any one of claims 1 to 5,
A shutter control unit that controls the opening / closing operation of the shutter by the first actuator driven by the actuator driving device;
An imaging apparatus comprising: a focus control unit that controls focus adjustment of an imaging optical system by the second actuator driven by the actuator driving apparatus.   The imaging apparatus according to claim 6, wherein the actuator driving device increases the amount of current supplied to the first actuator by changing the third duty ratio when the shutter is closed. The actuator driving device according to any one of claims 1 to 5,
A zoom control unit that changes a focal length of an imaging optical system by the first actuator driven by the actuator driving device;
An imaging apparatus comprising: a focus control unit configured to control focus adjustment of the imaging optical system by the second actuator driven by the actuator driving apparatus.   The imaging apparatus according to claim 8, wherein the actuator driving device increases the amount of current supplied to the first actuator by changing the third duty ratio at the start of zoom driving. A first half-bridge circuit having a first output terminal to which a first actuator is connected;
A second half bridge circuit having a second output terminal to which a second actuator is connected;
A third half bridge circuit having a third output terminal to which the first actuator and the second actuator are connected;
A first duty ratio setting unit for setting a first duty ratio related to the drive voltage output by the first half bridge circuit;
A second duty ratio setting unit for setting a second duty ratio related to the drive voltage output by the second half bridge circuit;
A third duty ratio setting unit for setting a third duty ratio related to the drive voltage output by the third half bridge circuit;
An actuator for determining a current amount of the first actuator and the second actuator and outputting a control signal to the first to third duty ratio setting units, and driving the first actuator and the second actuator; A control method executed by a drive device,
The step of determining the current amount of the first actuator and the second actuator by the current amount control unit, and the current supplied to the first actuator or the second actuator when driving the first actuator and the second actuator simultaneously A control method for an actuator driving apparatus, comprising: outputting a control signal for changing the third duty ratio according to the amount to the third duty ratio setting unit.

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