Actuator drive device and control method thereof

Abstract

To provide an actuator drive device capable of reducing magnetic field noise generated from a drive coil, through a simple constitution, and to provide a control method therefor.SOLUTION: An actuator drive device comprises a drive coil that generates driving force for driving an actuator via application of first and second voltages, and a control unit therefor. The control unit sets one of the first and second voltages to a first pulse and the other to the second pulse, and performs at least one of first control and second control. The first control modulates one pulse width among a first pulse and a second pulse in a larger change amount than the other change amount among pulse widths of the first pulse and the second pulse in such a manner that a pulse width during ON-time of the second pulse falls within a pulse width during ON-time of the first pulse, and the second control modulates one pulse width among the first pulse and the second pulse in a larger change amount than the other pulse width change amount among the first pulse and the second pulse in such a manner that a pulse width during ON-time of the first pulse falls within a pulse width during ON-time of the second pulse.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an actuator driving device and a control method thereof.

Background Art

[0002] In recent years, with the improvement in performance of imaging apparatuses, the number of imaging apparatuses equipped with a blur correction mechanism has been increasing. Examples of blur correction systems include a system in which an actuator driving device is mounted to move an optical lens in a direction orthogonal to the optical axis, and a system in which an imaging element is moved in a direction orthogonal to the optical axis. In the system of moving the imaging element, a system in which the imaging element is moved to perform blur correction by a so-called voice coil motor system using a magnet and a drive coil is common. In this voice coil motor system, PWM (Pulse Width Modulation) control is widely used. It is known that in this PWM control, magnetic field noise is generated as current flows through the drive coil, which causes effects on electronic devices.

[0003] In order to reduce the effect of magnetic field noise generated from the drive coil included in the actuator driving device on the imaging element, a control method has been proposed in which the current waveform flowing through the drive coil during forward and reverse energization by PWM control is smoothed into a substantially trapezoidal waveform, as described in Patent Document 1.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0005] However, even if the drive current waveform is formed into a roughly trapezoidal shape by providing a short-circuit period in which the two output terminals are short-circuited, as in the configuration described in Patent Document 1, the magnetic field becomes large when the duty cycle of the drive voltage applied to each output terminal is 50%. For this reason, it is difficult to reduce the magnetic field noise generated from the drive coil with a simple configuration in the configuration described in Patent Document 1.

[0006] Therefore, the object of the present invention is to provide an actuator drive device and a control method therefor that can reduce magnetic field noise generated from the drive coil with a simple configuration. [Means for solving the problem]

[0007] According to one aspect of the present invention, there is an actuator drive device having a first input terminal to which a first voltage is applied and a second input terminal to which a second voltage is applied, and a drive coil that generates a driving force to drive an actuator by applying the first voltage and the second voltage, and a control unit that controls the first voltage and the second voltage, wherein the control unit sets one of the first voltage and the second voltage as a first pulse and the other as a second pulse, and modulates the pulse width of one of the first pulse and the second pulse by a change amount greater than the change amount of the pulse width of the other of the first pulse and the pulse width of the other of the first pulse and the pulse width of the second pulse by a change amount greater than the change amount of the pulse width of the other of the first pulse and the pulse width.

[0008] According to another aspect of the present invention, there is a control method for an actuator drive device having a first input terminal to which a first voltage is applied and a second input terminal to which a second voltage is applied, and a drive coil that generates a driving force to drive an actuator by applying the first voltage and the second voltage, characterized in that at least one of the following is performed: first control, in which one of the first voltage and the second voltage is set to be a first pulse and the other to be a second pulse, and the pulse width of one of the first pulse and the second pulse is modulated by a change amount greater than the change amount of the pulse width of the other of the first pulse and the second pulse, so that the pulse width of the on-time of the second pulse is within the pulse width of the on-time of the first pulse; and second control, in which the pulse width of one of the first pulse and the second pulse is modulated by a change amount greater than the change amount of the pulse width of the other of the first pulse and the second pulse, so that the pulse width of the on-time of the first pulse is within the pulse width of the on-time of the second pulse. [Effects of the Invention]

[0009] According to the present invention, magnetic field noise can be reduced with a simple configuration. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram showing an actuator drive device according to the first embodiment. [Figure 2] This diagram illustrates the coil drive voltage for driving an actuator using an actuator drive device according to the first embodiment. [Figure 3] This diagram illustrates the coil drive voltage and coil drive current of the actuator drive device according to the first embodiment. [Figure 4] Figure 4 is a schematic graph showing the relationship between the driving force generated in the drive coil and the on-time, which is the duration during which the coil drive voltage is ON in one cycle of the PWM signal. [Figure 5]This graph shows the relationship between the duty cycle of the coil drive voltage by the actuator drive device and the fundamental frequency component. [Figure 6] This graph shows the relationship between the fixed pulse width and the frequency characteristics of the waveform in the drive voltage of the actuator drive device according to the first embodiment. [Figure 7] This graph shows the relationship between the fixed pulse width of the coil drive voltage by the actuator drive device according to the first embodiment and the maximum value of the fundamental frequency component of the waveform. [Figure 8] This figure illustrates the coil drive voltage by the actuator drive device according to the second embodiment. [Figure 9] This is a schematic diagram showing an actuator drive device according to the third embodiment. [Modes for carrying out the invention]

[0011] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, the embodiments described below are some embodiments of the present invention and are not limited thereto. Furthermore, explanations of components that are denoted by common reference numerals will be omitted as appropriate.

[0012] <First Embodiment> An actuator drive device and its control method according to a first embodiment of the present invention will be described with reference to Figures 1 to 7.

[0013] First, the configuration of the actuator drive device according to this embodiment will be explained using Figure 1. Figure 1 is a schematic diagram showing the actuator drive device 100 according to this embodiment. In this embodiment, the example will be described when the actuator drive device constitutes an image stabilization mechanism used in electronic devices (imaging devices) such as digital still cameras and digital video cameras. In addition, it can also be used, for example, in optical equipment such as interchangeable lenses mounted on interchangeable lens cameras to drive optical elements for image stabilization. A typical actuator used in an image stabilization mechanism is a voice coil motor. A voice coil motor is a moving coil type actuator and a linear motor. Note that the actuator drive device according to this embodiment is not limited to the case of constituting an image stabilization mechanism, but can be used to drive actuators in various devices. The motor used in the actuator drive device is not limited to a linear motor, but may also be a rotary motor, and it is not limited to a moving coil type actuator, but may also be a moving magnet type actuator. For example, it can also be used to drive motors that drive various mechanical elements (rollers, gears, etc.) in printing equipment (image forming devices) such as electrophotographic printers and inkjet printers. Alternatively, it can be used to drive mechanical elements (arms and stages) in industrial equipment such as robots and transport systems.

[0014] As shown in Figure 1, the actuator drive device 100 according to this embodiment includes a drive circuit 110 and a drive coil 111. The drive circuit 110 includes a first output unit 114, a second output unit 115, a first duty cycle setting unit 116, a second duty cycle setting unit 117, and a phase difference setting unit 118. The drive coil 111 is provided with a first input terminal 112 at one end and a second input terminal 113 at the other end.

[0015] The drive coil 111 is sandwiched between magnets (not shown) and arranged in a magnetic field formed by the magnets. A coil drive current flows through the drive coil 111 when a coil drive voltage is applied thereto from the drive circuit 110. When the coil drive current flows through the drive coil 111, a force is generated in accordance with Fleming's left-hand rule. The actuator drive device 100 can drive the actuator 200, which is the driving target, by using the force generated in the drive coil 111 as a driving force. Although the drive coil 111 is configured to be sandwiched between the magnets, it is sufficient that the magnetic field required for driving reaches the drive coil 111 from the magnets. Therefore, a configuration in which a magnet is disposed only on one of the surfaces of the drive coil 111 may be adopted. Further, although the force generated in the drive coil 111 is used as the driving force, a configuration in which the drive coil 111 is fixed and the force generated in the magnet is used as the driving force to drive the actuator 200 as the driving target may be adopted.

[0016] The actuator 200 is incorporated in a movable portion 210 that is movable in a predetermined direction. The movable portion 210 holds an image sensor 211. The image sensor 211 is provided in an imaging apparatus that captures images, and is an element that photoelectrically converts a light flux that has passed through a photographing optical system and is condensed by the photographing optical system. Therefore, the image sensor 211 can be moved together with the movable portion 210 by driving the actuator 200. In this way, the actuator drive device 100 constitutes a blur correction mechanism 400 that suppresses blurring of a captured image caused by a photographer's camera shake or the like to a small extent by moving the image sensor 211 through the driving of the actuator 200.

[0017] The shake correction mechanism 400 includes a magnetic sensor 410. The magnetic sensor 410 can detect the position of the movable portion 210 that is moved by driving of the actuator 200 using a magnetic circuit. As the magnetic sensor 410, for example, a Hall element or the like can be used. Note that as means for detecting the position of the movable portion 210, various position sensors can be used instead of the magnetic sensor 410. The actuator drive device 100 can perform feedback control by using a signal corresponding to the position of the movable portion 210 output by the magnetic sensor 410. The actuator drive device 100 can control the coil drive current supplied to the drive coil 111 based on the value of the signal from the magnetic sensor 410, and can control the direction related to the driving of the actuator 200.

[0018] Note that a plurality of the actuators 200 may be mounted. In this case, by controlling each of the plurality of actuators 200 with one or a plurality of actuator drive devices 100, the movable portion 210 can be moved not only in the rectilinear direction but also in the rotational direction to rotate, so that the movable portion 210 can be moved in any direction. The specific configurations of the actuator 200, the actuator 200, and the shake correction mechanism 400 using the same are not particularly limited, and any configuration can be adopted.

[0019] The first input terminal 112 and the second input terminal 113 respectively provided at one end and the other end of the drive coil 111 are terminal portions for applying a drive voltage to the drive coil 111, respectively. The drive coil 111 is connected to a drive circuit 110 which is a control unit that controls the drive voltage applied to the drive coil 111. That is, the first output portion 114 of the drive circuit 110 is connected to the first input terminal 112. The second output portion 115 of the drive circuit 110 is connected to the second input terminal 113.

[0020] The first output unit 114 is an output unit that outputs a first drive voltage 121 (see Figure 2), which is a first voltage applied to the first input terminal 112. The second output unit 115 is an output unit that outputs a second drive voltage 122 (see Figure 2), which is a second voltage applied to the second input terminal 113. The first drive voltage 121 and the second drive voltage 122 are voltages of pulse width modulation (PWM) signals, each with an on time or off time set according to a set duty cycle. The drive circuit 110 controls the driving force that drives the actuator 200 by changing the pulse width of the first drive voltage 121 and the second drive voltage 122, which are PWM signals applied to the drive coil 111 by the first output unit 114 and the second output unit 115.

[0021] The first output unit 114 and the second output unit 115 are, for example, driver ICs (Integrated Circuits) used for drive control of motors, and specifically, they are composed of H-bridge circuits used for drive control of motors, etc. Although the first output unit 114 and the second output unit 115 are described here as being composed of H-bridge circuits, it is sufficient if they can output the drive voltage described later, and the circuit configuration of the first output unit 114 and the second output unit 115 is not limited to this. The first output unit 114 is connected to the first duty cycle setting unit 116. The second output unit 115 is connected to the second duty cycle setting unit 117.

[0022] The first duty cycle setting unit 116 is a setting unit that sets the duty cycle of the first drive voltage 121, which is a PWM signal output from the first output unit 114, that is, a pulse width setting unit that sets the pulse width of the first drive voltage 121. The second duty cycle setting unit 117 is a setting unit that sets the duty cycle of the second drive voltage 122, which is a PWM signal output from the second output unit 115, that is, a pulse width setting unit that sets the pulse width of the second drive voltage 122. The first duty cycle setting unit 116 and the second duty cycle setting unit 117 are connected to a phase difference setting unit 118.

[0023] The phase difference setting unit 118 sets the phase difference between the first drive voltage 121 output from the first output unit 114 and the second drive voltage 122 output from the second output unit 115. The phase difference setting unit 118 sets the phase difference between the first drive voltage 121 and the second drive voltage 122 via the first duty cycle setting unit 116 and the second duty cycle setting unit 117.

[0024] Next, the coil drive voltage, which is the drive voltage for driving the actuator 200 by the actuator drive device 100 according to this embodiment, will be explained in detail with reference to Figure 2. Figure 2 is a diagram illustrating the coil drive voltage for driving the actuator 200 by the actuator drive device 100.

[0025] As shown in Figure 2, the drive circuit 110 applies a first drive voltage 121 and a second drive voltage 122 to the first input terminal 112 and the second input terminal 113 of the drive coil 111 via a first output unit 114 and a second output unit 115, respectively. The first drive voltage 121 and the second drive voltage 122 are PWM signals. The periods of the first drive voltage 121 and the second drive voltage 122 are the same. Since the drive of the actuator 200 is determined by the voltage or current applied to the drive coil 111, the coil drive voltage 125 that determines the drive of the actuator 200 is the potential difference generated across the drive coil 111. That is, the coil drive voltage 125 is the difference between the first drive voltage 121 and the second drive voltage 122.

[0026] The drive circuit 110 functions as a control unit that controls the first drive voltage 121 and the second drive voltage 122. The drive circuit 110 changes the pulse width of the waveforms of the first drive voltage 121 and the second drive voltage 122, which are PWM signals, in response to the drive of the actuator 200, but performs different control on the first drive voltage 121 and the second drive voltage 122. Specifically, the drive circuit 110 controls one of the first drive voltage 121 and the second drive voltage 122 by setting it as a modulated pulse 123 that modulates the pulse width, and controls the other as a fixed pulse 124 that fixes the pulse width. Therefore, the drive circuit 110 controls the driving force of the actuator 200 by pulse width modulation of the modulated pulse 123. Note that Figure 2 illustrates the case where the first drive voltage 121 is the modulated pulse 123 and the second drive voltage 122 is the fixed pulse 124, but it is also possible that the first drive voltage 121 is the fixed pulse 124 and the second drive voltage 122 is the modulated pulse 123.

[0027] The drive circuit 110 can perform pulse width modulation of the modulated pulse 123 by widening the pulse width of the modulated pulse 123 on both sides or narrowing the pulse width on both sides, with the pulse center of the modulated pulse 123 as the reference point.

[0028] Furthermore, the drive circuit 110 can set the modulation pulse 123 and the fixed pulse 124 so that the pulse width of the fixed pulse 124's on-time falls within the pulse width of the modulation pulse 123's on-time. Specifically, the drive circuit 110 can set the pulse width of the modulation pulse 123, the pulse width of the fixed pulse 124, and the phase difference between the modulation pulse 123 and the fixed pulse 124. The drive circuit 110 can perform these settings using the first duty cycle setting unit 116, the second duty cycle setting unit 117, and the phase difference setting unit 118. By performing this control, which keeps the modulation pulse 123 on when at least the fixed pulse 124 is on, it is not necessary to change the pulse width and phase relationship of the fixed pulse 124 with respect to the pulse center of the modulation pulse 123. By controlling the modulation pulse 123 and the fixed pulse 124 in this way, simple control can be performed on the fixed pulse 124, which always provides only a constant output.

[0029] As described above, by configuring the first drive voltage 121 and the second drive voltage 122 as a modulated pulse 123 and a fixed pulse 124, the coil drive voltage 125 can be made to have a waveform more suitable for reducing magnetic field noise. The mechanism for reducing magnetic field noise by the waveform of the coil drive voltage 125 will be described later.

[0030] In the above description, the drive circuit 110 controls the pulse width of the modulated pulse 123 by widening the pulse width on both sides or narrowing the pulse width on both sides with respect to the center of the pulse, but it is not limited to this. Instead of this control, the drive circuit 110 can also control the pulse width of the modulated pulse 123 by modulating it with respect to the rising edge of the pulse. In this case, the drive circuit 110 can set the phase difference of the fixed pulse 124 using the phase difference setting unit 118 so that the pulse width of the on-time of the fixed pulse 124 falls within the pulse width of the on-time of the modulated pulse 123.

[0031] In the drive circuit 110, the terminal that outputs the modulated pulse 123 and the terminal that outputs the fixed pulse 124 can be configured to switch between each other. That is, the drive circuit 110 can be configured to have a function to switch between the modulated pulse 123 and the fixed pulse 124, which are set as the first drive voltage 121 and the second drive voltage 122. In this case, for example, if the first drive voltage 121 is the modulated pulse 123 and the second drive voltage 122 is the fixed pulse 124, the first drive voltage 121 can be switched to the fixed pulse 124 and the second drive voltage 122 to the modulated pulse 123 by switching the terminals. The drive circuit 110 can perform these switches at the timing when the pulse width of the modulated pulse 123 and the pulse width of the fixed pulse 124 become equal. Specifically, for example, the drive circuit 110 can perform these switches at the timing when the pulse width of the modulated pulse 123 decreases to the same level as the pulse width of the fixed pulse 124. By switching the two pulses in this way, it is possible to switch between the modulated pulse 123 and the fixed pulse 124 while maintaining a highly linear change in the driving force of the actuator 200 associated with pulse width modulation. By switching the modulated pulse 123 and the fixed pulse 124 in this way, the direction of the current flowing through the drive coil 111 can be reversed, and the direction of the driving force applied to the actuator 200 can be reversed.

[0032] The modulated pulse 123 and the fixed pulse 124 can be switched between within a range that does not cause problems with the operation of the actuator 200. For example, within a range that does not cause problems with the operation of the actuator 200, the drive circuit 110 can be configured to switch between the modulated pulse 123 and the fixed pulse 124 from a state where there is a difference between the pulse widths of the modulated pulse 123 and the fixed pulse 124.

[0033] Furthermore, the function of switching between the modulated pulse 123 and the fixed pulse 124 in the drive circuit 110 is for the purpose of switching the driving force of the actuator 200 in the opposite direction. For this reason, if the direction of the driving force of the actuator 200 only needs to be in one direction, the drive circuit 110 may be configured without the function of switching between the modulated pulse 123 and the fixed pulse 124.

[0034] Next, the details of the coil drive voltage 125 will be explained using Figure 2 as an example, with the first drive voltage 121 being a modulated pulse 123 and the second drive voltage 122 being a fixed pulse 124. Note that when the first drive voltage 121 is a fixed pulse 124 and the second drive voltage 122 is a modulated pulse 123, the applied pulses are reversed, but the relationship between the modulated pulse 123 and the fixed pulse 124 remains the same, so the explanation will be omitted. Furthermore, the coil drive voltage 125 is a pulse waveform, and in Figure 2, the coil drive voltage 125 is shown as a square wave with extremely short rise and fall times. However, the waveform of the coil drive voltage 125 is not limited to this. Depending on the specifications of the drive circuit 110 and the driver IC that outputs the first drive voltage 121 and the second drive voltage 122, the waveform of the coil drive voltage 125 may have constant rise and fall times.

[0035] The drive circuit 110 can modulate the pulse width corresponding to the time the voltage is on by applying binary voltages, on and off, as the first drive voltage 121 and the second drive voltage 122, respectively. Therefore, the coil drive voltage 125 includes periods 130A, 130B, and 130C within one cycle of the PWM signal. Periods 130A, 130B, and 130C have different on / off states for the first drive voltage 121 and the second drive voltage 122.

[0036] Period 130A is the period when the first drive voltage 121 is off and the second drive voltage 122 is off. Period 130B is the period when the first drive voltage 121 is on and the second drive voltage 122 is off. Period 130C is the period when the first drive voltage 121 is on and the second drive voltage 122 is on.

[0037] The drive circuit 110 controls the modulated pulse 123 and the fixed pulse 124 so that the pulse width of the fixed pulse 124's on-time falls within the pulse width of the modulated pulse 123's on-time. Therefore, during the period 130C when the first drive voltage 121 is on and the second drive voltage 122 is also on, the pulse width is equivalent to that of the fixed pulse 124. Furthermore, within one cycle of the PWM signal, period 130B consists of two periods, period 130B1 and period 130B2, which are positioned so as to sandwich period 130C in time.

[0038] Furthermore, at the coil drive voltage 125, there is no period in which the first drive voltage 121 is off and the second drive voltage 122 is on. As a result, the coil drive voltage 125 is configured so that there is no period in one cycle of the PWM signal during which reverse current flows through the drive coil 111.

[0039] As described above, the drive circuit 110 controls the coil drive voltage 125 by combining the modulated pulse 123 and the fixed pulse 124 so that the waveform has two pulses during one period of the PWM signal. By controlling the coil drive voltage 125 in this way, the magnetic noise generated from the drive coil 111 is dispersed to higher frequencies in its frequency components, and the influence of magnetic noise reaching the image sensor 211 can be reduced. Details of this magnetic noise reduction effect will be described later.

[0040] Next, the coil drive current 126 flowing through the drive coil 111 during each period 130A, 130B, and 130C will be explained using Figure 3. Figure 3(a) is a schematic diagram showing an example of the waveform of two cycles of the coil drive voltage 125 shown in Figure 2 and the coil drive current 126 flowing between them, as performed by the actuator drive device 100 according to this embodiment. Figure 3(b) is a schematic diagram showing an example of two cycles of the coil drive voltage 127 using a general PWM signal and the waveform of the coil drive current 128 flowing between them, for comparison.

[0041] The coil drive current 126 shown in Figure 3(a) refers to the current flowing through the drive coil 111. The drive coil 111 has an electrically inductive value. Therefore, an electromotive force is generated in the drive coil 111 that opposes the increase or decrease of the current due to the on / off change of the coil drive voltage 125 applied to the drive coil 111 by the drive circuit 110. Due to this electromotive force, in period 130B, which consists of periods 130B1 and 130B2, the coil drive current 126 flowing from the first input terminal 112 to the second input terminal 113 has a gradually increasing slope. Conversely, in periods 130A and 130C, the coil drive current 126 flowing from the first input terminal 112 to the second input terminal 113 has a gradually decreasing slope.

[0042] As explained in the description of the coil drive voltage 125, there is no period in one cycle of the PWM signal during which current flows from the second input terminal 113 to the first input terminal 112. Therefore, the coil drive current 126 is configured so that current flows from the first input terminal 112 to the second input terminal 113 throughout the entire period of periods 130A, 130B, and 130C. The coil drive current 126 has a slope that increases or decreases during periods 130A, 130B, and 130C. By configuring the coil drive current 126 in this way, it is avoided that a reverse force will act during one cycle of the PWM signal, reducing the driving force of the actuator 200. As can be seen from period 131, which is one cycle based on the start of period 130B1, the coil drive current 126 forms a waveform composed of two triangular waves during one cycle.

[0043] In contrast, Figure 3(b) shows the coil drive voltage 127 and coil drive current 128 for a typical PWM signal. The coil drive voltage 127 has one pulse during one cycle of the PWM signal. The coil drive current 128, like the coil drive current 126, has a slope where the current gradually decreases during period 132A, which is the off period of the coil drive voltage 127, and a slope where the current gradually increases during period 132B, which is the on period. As can be seen from period 133, which is one cycle based on the start of period 132B, the coil drive current 128 forms a waveform consisting of one triangular wave during one cycle. Although the number of pulses formed during one cycle differs between the coil drive voltage 125 and the coil drive voltage 127, the same driving force can be generated by the actuator 200 if the on time of the pulses during one cycle of the PWM signal is the same.

[0044] Therefore, according to Figure 3, if periods 130B and 132B have the same pulse width, the same driving force can be generated by the actuator 200. The current changes associated with the on / off changes of the coil driving voltages 125 and 127, which are present in the coil driving currents 126 and 128, can be determined by the resistance value R and inductance value L of the driving coil 111, as well as the driving frequency of the PWM signal. This can be determined from a typical RL series circuit consisting of inductance value L and resistance value R.

[0045] In this embodiment, for example, the driving frequency of the PWM signal can be set to several tens [kHz] to several hundred [kHz], the resistance value of the driving coil 111 can be set to 10 [Ω], and the inductance value of the driving coil 111 in the driving frequency band can be set to approximately 100 [μH]. Under these conditions, the current changes associated with the on / off changes of the coil driving voltages 125 and 127 of the coil driving current 126 and coil driving current 128 are generally linear. Therefore, in this embodiment, the coil driving current 126 is a triangular wave. However, the waveform of the coil driving current 126 is not limited to this. If the driving frequency of the PWM signal, the resistance value and inductance value of the driving coil 111 are different from the above case, the current change of the coil driving current 126 may become nonlinear, and a waveform that deviates from an ideal triangular wave may be formed in the coil driving current 126.

[0046] Here, the relationship between the driving force generated in the drive coil 111 and the on-time of the coil drive voltage 125, as well as the waveform states of the corresponding first drive voltage 121, second drive voltage 122, and coil drive voltage 125, will be explained using Figure 4. Figure 4 is a schematic graph showing the relationship between the driving force generated in the drive coil 111 and the on-time, which is the time width during which the coil drive voltage 125 is turned on in one cycle of the PWM signal. In the graph shown in Figure 4, the horizontal axis represents the on-time, with a positive on-time indicating that the pulse width of the first drive voltage 121 is larger than that of the second drive voltage 122, and a negative on-time indicating that the pulse width of the second drive voltage 122 is larger than that of the first drive voltage 121. The vertical axis represents the driving force, with a positive driving force indicating that the pulse width of the first drive voltage 121 is larger than that of the second drive voltage 122, and a negative driving force indicating that the pulse width of the second drive voltage 122 is larger than that of the first drive voltage 121. The graph also shows the waveform states S0, S11, S12, S21, and S22 of the first drive voltage 121, the second drive voltage 122, and the coil drive voltage 125.

[0047] As shown in Figure 4, the driving force deforms linearly, for example, according to the variation in the on-time. On the positive on-time side, the first driving voltage 121 is the modulated pulse 123, and the second driving voltage 122 is the fixed pulse 124. On the negative on-time side, the first driving voltage 121 is the fixed pulse 124, and the second driving voltage 122 is the modulated pulse 123. At the origin O, where the on-time is 0, the first driving voltage 121 and the second driving voltage 122 can be either the modulated pulse 123 or the fixed pulse 124, respectively. In these cases, the pulse width center of the modulated pulse 123 and the pulse width center of the fixed pulse 124 always overlap.

[0048] State S0 is the state at the origin O. In state S0, the duty cycles [%] of the first drive voltage 121 and the second drive voltage 122, which are one of the modulated pulse 123 and the fixed pulse 124 and the other, are set to, for example, 10% and are equal to each other. Therefore, no driving force is generated in state S0.

[0049] States S11 and S12 are the states when the first drive voltage 121 is a modulated pulse 123 and the second drive voltage 122 is a fixed pulse 124 with a duty cycle [%] of, for example, 10%. The pulse width of the modulated pulse 123 is wider in state S12 than in state S11. Between state S0 and state S12, as shown in states S11 and S12, the magnitude of the driving force increases as the pulse width of the modulated pulse 123 increases.

[0050] On the other hand, states S21 and S22 are the states when the first drive voltage 121 is a fixed pulse 124 with a duty cycle [%] of, for example, 10%, and the second drive voltage 122 is a modulated pulse 123. The pulse width of the modulated pulse 123 is wider in state S22 than in state S21. Between state S0 and state S22, as shown in states S21 and S22, the magnitude of the driving force in the opposite direction to states S11 and S22 becomes larger as the pulse width of the modulated pulse 123 widens.

[0051] The drive circuit 110 can control the magnitude of the driving force by changing the pulse width of the modulated pulse 123 between state S0 and state S12, where the first driving voltage 121 is the modulated pulse 123 and the second driving voltage 122 is the fixed pulse 124. Furthermore, the drive circuit 110 can control the magnitude of the driving force by changing the pulse width of the modulated pulse 123 between state S0 and state S22, where the first driving voltage 121 is the fixed pulse 124 and the second driving voltage 122 is the modulated pulse 123. In these cases, the fixed pulse 124 may be a pulse with a variable pulse width. However, the drive circuit 110 modulates the pulse width of the modulated pulse 123 by a larger change in pulse width than the change in pulse width of the pulse with a variable pulse that replaces the fixed pulse 124. The amount of change here is an absolute value.

[0052] In other words, the drive circuit 110 can perform a first control between state S0 and state S12, and a second control between state S0 and state S22, and can switch between the first and second controls. As the first control, the drive circuit 110 modulates the pulse width of the first drive voltage 121 by a larger change than the change in the pulse width of the second drive voltage 122, so that the pulse width of the on-time of the second drive voltage 122 falls within the pulse width of the on-time of the first drive voltage 121. Furthermore, as the second control, the drive circuit 110 modulates the pulse width of the second drive voltage 122 by a larger change than the change in the pulse width of the first drive voltage 121, so that the pulse width of the on-time of the first drive voltage 121 falls within the pulse width of the on-time of the second drive voltage 122.

[0053] Furthermore, in the first control, the drive circuit 110 can set the first drive voltage 121 and the second pulse such that the timing of the center of the pulse of the first drive voltage 121 falls within the pulse width of the second drive voltage 122. Furthermore, in the second control, the drive circuit 110 can set the first drive voltage 121 and the second drive voltage 122 such that the timing of the center of the pulse of the second drive voltage 122 falls within the pulse width of the first drive voltage 121. Furthermore, in at least one of the first and second control, the drive circuit 110 can set the first drive voltage 121 and the second drive voltage 122 such that the center timing of the first drive voltage 121 and the center timing of the first drive voltage 122 overlap.

[0054] Furthermore, at the timing of switching between the first control and the second control, the drive circuit 110 can set the duty cycle of the pulse widths of the first drive voltage 121 and the second drive voltage 122 to within 4 to 35%.

[0055] Next, we will explain the mechanism by which magnetic field noise is generated in the actuator 200 and how this magnetic field noise reaches the image sensor 211, causing distortion in the image captured by the image sensor 211. When a periodically changing PWM signal flows through the drive coil 111, magnetic field noise is generated from the drive coil 111. When this magnetic field noise reaches the image sensor 211, the image captured by the image sensor 211 becomes distorted, resulting in, for example, horizontal stripe-like image noise. The magnetic field noise generated from the drive coil 111 by the PWM signal has multiple frequency components depending on the shape of the waveform. The image sensor 211 also has operating frequencies associated with its operations, such as the period for reading light and the transfer period for transferring the read light information to the circuit. Therefore, the way the image is distorted differs depending on the multiple frequency components of the image noise. Specifically, the spacing and intensity of the horizontal stripes in the image noise change. Therefore, by considering each frequency component separately and suppressing the frequency component of magnetic field noise that has a large impact as image noise, it is possible to suppress the magnetic field noise affecting the image sensor 211 and reduce image distortion.

[0056] The actuator drive device 100 according to this embodiment reduces the influence of magnetic noise reaching the image sensor 211 by forming two pulses during one cycle of the PWM signal at the coil drive voltage 125. The effect of this magnetic field noise will be explained below.

[0057] Figure 5 shows the characteristics of the fundamental frequency component of the PWM signal that changes with the drive of the actuator 200. Here, the drive change refers to the change in the duty cycle (Duty) [%] of the pulse width in the PWM signal. When a typical PWM signal, such as the one shown in Figure 3(b), is considered separately for each frequency component based on the Duty [%] change, it is generally known that the voltage that is maximum, excluding the DC component, is the fundamental frequency component when the Duty [%] is 50%. Therefore, for the purpose of comparing the effects of this embodiment, Figure 5 shows the change in the fundamental frequency component with respect to the Duty [%] change. Figure 5(a) shows the change in the fundamental frequency component when the Duty of the coil drive voltage 127 of the typical PWM signal shown in Figure 3(b) is changed.

[0058] Figure 5(b) shows the change in the fundamental frequency component when the Duty[%] of the modulated pulse 123 is changed, under the condition that the pulse width center of the modulated pulse 123 and the pulse width center of the fixed pulse 124 always overlap. In Figure 5(b), the second drive voltage 122 shown in Figure 2 is used as the fixed pulse 124 with a fixed Duty[%], and the first drive voltage 121 shown in Figure 2 is used as the modulated pulse 123 with a variable Duty[%]. In the graphs shown in Figures 5(a) and 5(b), the horizontal axis is Duty[%], and the vertical axis is the magnitude of the fundamental frequency component of the PWM signal in the waveform. In Figure 5(b), the Duty[%] is a period of 130B for one cycle of the PWM signal, and period 130B is the sum of period 130B1 and period 130B2. In Figures 5(a) and 5(b), the amplitudes of the coil drive voltage 125 and coil drive voltage 127 are set to 5[V], respectively.

[0059] As shown in Figure 5(a), the coil drive voltage 127, which is a typical PWM signal, has its fundamental frequency component minimized when the duty cycle is 0% and 100%. Then, when the duty cycle is 50%, the fundamental frequency component is maximized, as shown by point 141, with a maximum value of 3.18V.

[0060] In contrast, according to this embodiment, as shown in Figure 5(b), the fundamental frequency component is maximized at point 142 when the duty cycle is 35%, with a maximum value of 1.39V. Therefore, according to this embodiment, the largest fundamental frequency component among the frequency components of the coil drive voltage 125 can be reduced. Thus, according to this embodiment, the magnetic field noise of the fundamental frequency component generated from the drive coil 111 can be reduced, and image distortion occurring in the image captured by the image sensor 211 can be reduced.

[0061] Next, as shown in Figure 5, the mechanism by which the fundamental frequency component of magnetic field noise is reduced by applying this embodiment will be explained using Figure 6. Figure 6 is a graph showing the frequency components of the waveforms that form points 141 and 142, where the fundamental frequency components of the coil drive voltage 127 and coil drive voltage 125, respectively, are maximized, as shown in Figure 5. In Figure 6, the black squares (■) represent the frequency components of the coil drive voltage 127, which is a typical PWM signal, and the white triangles (△) represent the frequency components of the coil drive voltage 125 according to this embodiment. In Figure 6, the horizontal axis is the frequency axis, and the fundamental wave and the 2nd to 7th harmonics of the PWM signal are shown. In Figure 6, f1 represents the fundamental frequency, and f2 to f7 represent the 2nd to 7th harmonics, respectively. The vertical axis shows the magnitude of the voltage for each frequency. The horizontal axis shows the fundamental wave and its integer multiples (harmonics) because, according to generally known principles, a signal with a repeating period can be decomposed into a fundamental wave component and its integer multiples (harmonics).

[0062] From Figure 6, it can be seen that the coil drive voltage 127, indicated by ■, consists of a fundamental frequency component that is maximum when the Duty Cycle is 50%, excluding the DC component, and odd-numbered harmonics of the fundamental wave that decrease with increasing frequency. This is because, as shown in Figure 3(b), the coil drive voltage 127 is a waveform with one pulse per period, and the voltage level of the waveform is concentrated at the fundamental frequency and odd-numbered harmonics of the fundamental wave. The detailed principle that the frequency components of the coil drive voltage 127 indicated by ■ consist of a fundamental frequency component and odd-numbered harmonics of the fundamental wave can be obtained from the Fourier transform of a general square wave.

[0063] As explained in Figure 5, the coil drive voltage 125, indicated by △, is able to reduce the fundamental frequency component compared to the coil drive voltage 127, indicated by ■. Furthermore, it can be seen that the coil drive voltage 125 has even multiples of the fundamental frequency component, which is not present in the coil drive voltage 127, in addition to the odd multiples of the fundamental frequency component. It can also be seen that the odd multiples of the fundamental frequency component in the coil drive voltage 125 differs in value from the odd multiples of the fundamental frequency component in the coil drive voltage 127, showing a slight increase or decrease. This is because, in this embodiment, the coil drive voltage 125 has a configuration with two pulses per period, as shown in Figure 3(a). Specifically, because the coil drive voltage 125 has two pulses per period, the frequency components of the waveform are dispersed to higher frequency components compared to the coil drive voltage 127 shown in Figure 3(b). In this way, by distributing a portion of the highest voltage level in the waveform across different frequencies, the magnetic field noise component that affects image distortion in the image captured by the image sensor 211 can be reduced.

[0064] In this embodiment, the modulated pulse 123 and the fixed pulse 124 are set so that the pulse width of the on-time of the fixed pulse 124 falls within the pulse width of the on-time of the modulated pulse 123, but the embodiment is not limited to this. Preferably, the modulated pulse 123 and the fixed pulse 124 can be set so that the timing of the pulse center of the modulated pulse 123 falls within the pulse width of the fixed pulse 124. By setting the modulated pulse 123 and the fixed pulse 124 in this way, the pulse widths of period 130B1 and period 130B2 become closer, and a higher frequency dispersion effect can be obtained. More preferably, the modulated pulse 123 and the fixed pulse 124 can be set so that the timing of the pulse center of the modulated pulse 123 and the timing of the pulse center of the fixed pulse 124 are synchronized, that is, so that the two timings overlap. By setting the modulated pulse 123 and the fixed pulse 124 in this way, period 130B1 and period 130B2 become approximately the same length, and as a result, an even higher frequency dispersion effect can be obtained. Furthermore, the drive circuit 110 can perform settings related to these modulated pulses 123 and fixed pulses 124 using the first duty cycle setting unit 116, the second duty cycle setting unit 117, and the phase difference setting unit 118.

[0065] As described above, in this embodiment, by forming two pulses within one period in the waveform of the coil drive voltage 125, magnetic field noise is dispersed into high-frequency components, thereby reducing magnetic field noise that causes image distortion in the image captured by the image sensor 211. At this time, the effect of reducing magnetic noise also changes depending on the pulse width of the off period 130C, which is the off period between the two pulses. This point will be explained using Figure 7. In Figure 7, the horizontal axis shows the Duty[%], which is the ratio of the pulse width of the period 130C in the coil drive voltage 125 to one period of the PWM signal. The vertical axis shows the maximum voltage value of the fundamental frequency component obtained when the Duty of the period 130C is changed for each waveform having a period 130C. For example, when the Duty of the period 130C is 0[%], it shows the case where the coil drive voltage 125 has a waveform that is generally a PWM signal, as shown in Figure 3(b).

[0066] As can be seen from Figure 7, in the interval where the duty cycle for the 130C period is 0 to 17%, increasing the duty cycle for the 130C period reduces the voltage level of the fundamental frequency component of the coil drive voltage 125. On the other hand, when the duty cycle for the 130C period is in the interval of 17 to 50%, the voltage level of the fundamental frequency component of the coil drive voltage 125 increases with increasing duty cycle for the 130C period. This is because, since the PWM signal is a repeating waveform, the waveform of the first period and the waveform of the adjacent second period combine to form a waveform with a large fundamental frequency component.

[0067] As shown in Figure 7, according to this embodiment, even when the duty cycle for period 130C is in the range of 17-50%, the voltage level of the fundamental frequency component can be reduced compared to conventional general waveforms. When the duty cycle for period 130C is 50% or more, the pulse width for period 130C is large, more than half of one period, so the voltage level of the fundamental frequency component is reduced as the period 130C increases. More specifically, the maximum pulse width that can be output by combining the waveforms of adjacent periods decreases as the period 130C increases, so the voltage level of the fundamental frequency component of the combined waveform is reduced.

[0068] Thus, according to this embodiment, even considering the synthesis with adjacent signals due to the repetition of the PWM signal, the voltage level of the fundamental frequency component of the coil drive voltage 125 can be reduced. Here, since period 130C is the off period of the coil drive voltage 125, as period 130C increases, the maximum torque that the actuator 200 can output decreases. Therefore, considering the maximum torque of the actuator 200, it is preferable that period 130C or the pulse width of the fixed pulse 124 forming period 130C be smaller. Furthermore, it is more preferable that the pulse width of the fixed pulse 124 has a duty cycle within 4 to 35%. The drive circuit 110 can control the first drive voltage 121 and the second drive voltage 122 so that these preferred conditions are met. By adopting such a configuration, the voltage level of the fundamental frequency component of the coil drive voltage 125 can be reduced by at least 10% or more while maintaining the driving force of the actuator 200.

[0069] As described above, according to this embodiment, the coil drive voltage 125 is formed by the modulated pulse 123 and the fixed pulse 124, thereby forming two pulses within one period of the PWM signal in the coil drive voltage 125. By forming the coil drive voltage 125 in this way, the magnetic field noise generated from the drive coil 111 is dispersed into higher frequency components, and image distortion occurring in the image captured by the image sensor 211 can be reduced.

[0070] In this embodiment, the case in which the pulse width of the fixed pulse 124 is fixed to a constant value has been described, but the embodiment is not limited to this. The pulse width of the fixed pulse 124 may vary within a range that does not cause problems in the operation of the actuator 200. For example, the pulse width of the pulse corresponding to the fixed pulse 124 may be configured to vary by a small amount of variation relative to the modulated pulse 123. In this case, the drive circuit 110 modulates the pulse width of the modulated pulse 123 by an amount of change that is larger than the amount of change in the pulse width of the small variation pulse. Thus, a pulse corresponding to the fixed pulse 124, which has a relatively small variation range relative to the modulated pulse 123, can be called a small variation pulse. The fixed pulse 124 is an example of a small variation pulse. The small variation pulse may also be a modulated pulse whose pulse width can be modulated. Note that the amount of change here is an absolute value. The amount of change can be rephrased as the variation range. It is preferable that the variation range of the small variation pulse is sufficiently small compared to the variation range of the modulated pulse 123. As a sufficiently small fluctuation range, the change in the pulse width of the fixed pulse 124 can be set to preferably within ±4%, more preferably within ±2%, of the duty cycle that serves as the reference for the pulse width of the fixed pulse 124. Specifically, as a sufficiently small fluctuation range, it is desirable that the duty cycle is within ±4% so as not to impair the performance of the image stabilization mechanism that suppresses blurring of captured images. In addition, the duty cycle may be set to ±2% in order to make maximum use of the linearity of the driver IC used for drive control of motors, etc. If the fluctuation range of a small fluctuation pulse is within ±1%, it may be considered a fixed pulse. It is preferable that the fluctuation range or change amount of a small fluctuation pulse or a fixed pulse is zero.

[0071] The configuration of the image stabilization mechanism and related configurations using the actuator 200 driven by the actuator drive device 100 according to this embodiment are not particularly limited, and various configurations can be adopted. For example, a conductive shielding member can be provided between the image sensor 211 and the drive coil 111. With such a configuration, a higher magnetic noise reduction effect can be obtained. In this case, it is desirable that the conductive shielding member has a thickness and conductivity greater than or equal to the skin thickness in order to enhance the shielding effect, but the skin thickness can be reduced by increasing the frequency of the noise to be shielded, thereby enhancing the shielding effect. According to this embodiment, the magnetic field noise generated from the drive coil 111 is dispersed into higher frequency components, so the shielding effect of the conductive shielding member can also be enhanced. The conductive shielding member is preferably a non-magnetic conductor, and for example, magnesium alloy, aluminum, copper, etc. can be used.

[0072] <Second Embodiment> A second embodiment of the present invention, an actuator drive device and its control method, will be described with reference to Figure 8. Figure 8 is a diagram illustrating the coil drive voltage of the actuator drive device according to this embodiment.

[0073] The basic configuration of the actuator drive device according to this embodiment is the same as that shown in the first embodiment, so a description will be omitted. The difference between this embodiment and the first embodiment lies in the relationship between the pulse width and timing of the modulated pulse 223 and the fixed pulse 224 in the coil drive voltage 225. The coil drive voltage 225 for driving the actuator 200 with the actuator drive device 100 according to this embodiment will be described below with reference to Figure 8. Figure 8 shows the coil drive voltage 225 when the fixed pulse 224 is applied to the first drive voltage 221 and the modulated pulse 223 is applied to the second drive voltage 222 in the actuator drive device 100 according to this embodiment.

[0074] In this embodiment as well, the drive circuit 110 applies a binary voltage, on and off, as the first drive voltage 221 to the first input terminal 112 via the first output unit 114, similar to the first embodiment. The drive circuit 110 also applies a binary voltage, on and off, as the second drive voltage 222 to the second input terminal 113 via the second output unit 115. The drive circuit 110 can modulate the pulse width corresponding to the time the voltage is on. The coil drive voltage 225 is the potential difference generated across the drive coil 111 and is the difference between the first drive voltage 221 and the second drive voltage 222. As a result, in this embodiment as well, it is possible to modulate the pulse width corresponding to the on time. Therefore, the coil drive voltage 225 includes periods 230A, 230B, and 230C within one cycle of the PWM signal in which the on and off states of the first drive voltage 221 and the second drive voltage 222 are different from each other.

[0075] Period 230A is the period when the first drive voltage 221 is off and the second drive voltage 222 is off. Period 230B is the period when the first drive voltage 221 is on and the second drive voltage 222 is off. Period 230C is the period when the first drive voltage 221 is on and the second drive voltage 222 is on.

[0076] The drive circuit 110 controls the modulated pulse 223 and the fixed pulse 224 so that the pulse width of the on-time of the modulated pulse 223 falls within the pulse width of the on-time of the fixed pulse 224. Therefore, the period 230C in which the first drive voltage 221 is on and the second drive voltage 222 is also on is equivalent to the pulse width of the modulated pulse 223. Furthermore, within one cycle of the PWM signal, period 230B consists of two periods, period 230B1 and period 230B2, which are positioned so as to sandwich period 230C in time. Thus, in this embodiment as well, the drive circuit 110 controls the coil drive voltage 225 by combining the modulated pulse 223 and the fixed pulse 224 so that the waveform has two pulses within one cycle of the PWM signal.

[0077] As described above, according to this embodiment, the coil drive voltage 225 is formed by the modulated pulse 223 and the fixed pulse 224, thereby forming two pulses within one period of the PWM signal in the coil drive voltage 225. By forming the coil drive voltage 225 in this way, the magnetic field noise generated from the drive coil 111 is dispersed into higher frequency components, and image distortion occurring in the image captured by the image sensor 211 can be reduced.

[0078] In this embodiment, the modulation pulse 223 and the fixed pulse 224 are set so that the pulse width of the on-time of the modulation pulse 223 falls within the pulse width of the on-time of the fixed pulse 224, but the embodiment is not limited to this. Preferably, the modulation pulse 223 and the fixed pulse 224 can be set so that the timing of the pulse center of the fixed pulse 224 falls within the pulse width of the modulation pulse 223. By setting the modulation pulse 223 and the fixed pulse 224 in this way, the pulse widths of period 230B1 and period 230B2 become closer, and a higher frequency dispersion effect can be obtained. More preferably, the modulation pulse 223 and the fixed pulse 224 can be set so that the timing of the pulse center of the fixed pulse 224 and the timing of the pulse center of the modulation pulse 223 are synchronized, that is, so that the two timings overlap. By setting the modulation pulse 223 and the fixed pulse 224 in this way, period 230B1 and period 230B2 become approximately the same length, and as a result, an even higher frequency dispersion effect can be obtained.

[0079] In this embodiment as well, the drive circuit 110 can be configured to have a function to switch between the modulated pulse 223 and the fixed pulse 224, which are set as the first drive voltage 221 and the second drive voltage 222. The drive circuit 110 can perform these switches at the timing when the pulse width of the modulated pulse 223 and the pulse width of the fixed pulse 224 become equal. Specifically, for example, the drive circuit 110 can perform these switches at the timing when the pulse width of the modulated pulse 223 increases to the same level as the pulse width of the fixed pulse 224.

[0080] Furthermore, in this embodiment as well, the first control and the second control can be switched, similar to the first embodiment. In this embodiment, for example, in the first control, the first drive voltage 221 is a fixed pulse 224 and the second drive voltage 222 is a modulated pulse 223, and in the second control, the first drive voltage 221 is a modulated pulse 223 and the second drive voltage 222 is a fixed pulse 224. In this case, as the first control, the drive circuit 110 modulates the pulse width of the second drive voltage 222 by a change amount greater than the change amount of the pulse width of the first drive voltage 221, so that the pulse width of the on-time of the second drive voltage 222 is within the pulse width of the on-time of the first drive voltage 221. Furthermore, as a second control, the drive circuit 110 modulates the pulse width of the first drive voltage 221 by a larger change amount than the change amount of the pulse width of the second drive voltage 222, so that the pulse width of the on-time of the first drive voltage 221 falls within the pulse width of the on-time of the second drive voltage 222.

[0081] Furthermore, in this embodiment as well, similar to the first embodiment, a modulated pulse whose pulse width can be modulated can be used instead of the fixed pulse 224. For example, the pulse width of the fixed pulse 224 may be configured to vary by a sufficiently small amount relative to the modulated pulse 223. That is, the drive circuit 110 can modulate the pulse width of the modulated pulse 223 by a larger amount of change than the amount of change in pulse width of the pulse whose pulse width changes, which replaces the fixed pulse 224.

[0082] <Third Embodiment> An actuator drive device and its control method according to a second embodiment of the present invention will be described with reference to Figure 9. Figure 9 is a schematic diagram showing the actuator drive device 100 according to this embodiment.

[0083] The basic configuration of the actuator drive device according to this embodiment is the same as that shown in the first embodiment, so a detailed explanation will be omitted. The difference between this embodiment and the first embodiment is that the actuator drive device 100 has a filter circuit 300 between the drive circuit 110 and the drive coil 111. The actuator drive device 100 according to this embodiment will be described below with reference to Figure 9.

[0084] As shown in Figure 9, the actuator drive device 100 according to this embodiment has a filter circuit 300 in addition to the configuration shown in Figure 1. The filter circuit 300 is provided between the drive circuit 110 and the drive coil 111.

[0085] The filter circuit 300 has an inductor 301 and a capacitor 302, and is a so-called low-pass filter circuit composed of these. The inductor 301 is provided between the first output section 114 and the first input terminal 112, which are connected to each other. The capacitor 302 is provided to connect one point between the inductor 301 and the first input terminal 112, which are connected to each other, and one point between the second output section 115 and the second input terminal 113, which are connected to each other.

[0086] The first output unit 114 outputs one of the modulated pulse 123 and the fixed pulse 124 as the first drive voltage 121 to the first input terminal 112 via the filter circuit 300. The second output unit 115 outputs the other of the modulated pulse 123 and the fixed pulse 124 as the second drive voltage 122 to the second input terminal 113 via the filter circuit 300. As a result, the drive circuit 110 can apply the coil drive voltage 125 to the drive coil 111 via the filter circuit 300.

[0087] As described above, in this embodiment, the filter circuit 300 is provided so that the modulated pulse 123 and fixed pulse 124 output from the drive circuit 110 are applied to the drive coil 111 via the filter circuit 300. Because the signal is passed through the filter circuit 300, frequency components of the signal applied to the drive coil 111 that are higher than the cutoff frequency are reduced. This reduces the magnetic noise generated from the drive coil 111.

[0088] However, since the inductor 301, which is part of the low-pass filter circuit, also has an internal winding structure, a magnetic field is generated from the inductor 301 when current flows through it. This magnetic field reaches the image sensor 211, causing magnetic noise in the image signal or video signal of the image sensor 211, resulting in image distortion in the image captured by the image sensor 211.

[0089] In contrast, in this embodiment, the coil drive voltage 125 is formed by a modulated pulse 123 and a fixed pulse 124, thereby forming two pulses within one period of the PWM signal in the waveform of the coil drive voltage 125. This disperses the magnetic field noise generated from the drive coil 111 into higher frequency components, thereby reducing image distortion in the image captured by the image sensor 211. Therefore, in this embodiment, even magnetic field noise generated from the inductor 301, which constitutes part of the filter circuit 300, can be dispersed into higher frequency components.

[0090] In this embodiment, the signal applied to the drive coil 111 passes through the filter circuit 300. Therefore, in this embodiment, in addition to the dispersion of signal components that cause magnetic field noise due to the coil drive voltage 125 to high-frequency components, the effect of attenuation of high-frequency components by the filter circuit 300 can also be obtained. Because the attenuation effect of the filter circuit 300 is at high frequencies, the propagation of more noise signals can be blocked. Therefore, according to this embodiment, the filtering effect of the filter circuit 300 can also be further enhanced.

[0091] As described above, according to this embodiment, the coil drive voltage 125 is formed by the modulated pulse 123 and the fixed pulse 124, thereby forming two pulses within one period of the PWM signal in the coil drive voltage 125. By forming the coil drive voltage 125 in this way, the magnetic field noise generated from the inductor 301, which constitutes part of the filter circuit 300, is dispersed into higher frequency components, and image distortion occurring in the image captured by the image sensor 211 can be reduced.

[0092] Furthermore, according to this embodiment, since the noise components of the signal output to the inductor 301 are dispersed into higher frequency components, the filtering effect of the filter circuit 300 can be enhanced. As a result, the noise components propagating to the drive coil 111 are reduced, and image distortion occurring in the image captured by the image sensor 211 can be reduced.

[0093] In this embodiment, a case in which a filter circuit 300 is further provided in the actuator drive device 100 according to the first embodiment has been described, but the invention is not limited thereto. When a filter circuit 300 is further provided in the actuator drive device 100, in addition to forming the coil drive voltage 125 as in the first embodiment, a coil drive voltage 225 may be formed as in the second embodiment.

[0094] <Other Embodiments> Some of the embodiments described above can be omitted. For example, the drive circuit 110 may be configured to perform only one of the first and second controls described above. In other words, the drive circuit 110 only needs to perform at least one of the first and second controls. Furthermore, multiple embodiments described above can be combined. For example, the drive circuit 110 may be configured to execute both a drive mode based on the first embodiment and a drive mode based on the second embodiment, and it may be possible to select the drive mode to execute as required. The present invention can also be realized by supplying a program that implements one or more of the functions of the embodiments described above to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0095] This embodiment includes the following configurations and methods. (Composition 1) A drive coil having a first input terminal to which a first voltage is applied and a second input terminal to which a second voltage is applied, and which generates a driving force to drive an actuator by applying the first voltage and the second voltage, It has a control unit that controls the first voltage and the second voltage, The control unit, One of the first voltage and the second voltage is set to be the first pulse and the other to be the second pulse. A first control that modulates the pulse width of one of the first and second pulses by a larger change than the change in the pulse width of the other pulse, such that the pulse width of the on-time of the second pulse falls within the pulse width of the on-time of the first pulse. A second control that modulates the pulse width of one of the first and second pulses by a larger change than the change in the pulse width of the other pulse, such that the pulse width of the on-time of the first pulse falls within the pulse width of the on-time of the second pulse. Do at least one of the following: An actuator drive device characterized by the following: (Configuration 2) In the first control, the amount of change in the pulse width of the second pulse is within ±4% of the duty cycle that serves as the reference for the pulse width of the second pulse. The actuator drive device according to configuration 1, characterized in that... (Composition 3) In the first control, the second pulse is a fixed pulse. The actuator drive device according to configuration 2, characterized in that (Composition 4) In the second control, the amount of change in the pulse width of the first pulse is within ±4% of the duty cycle that serves as the reference for the pulse width of the first pulse. The actuator drive device according to configuration 2, characterized in that (Composition 5) In the second control, the first pulse is a fixed pulse. The actuator drive device according to configuration 4, characterized by the features described above. (Composition 6) The control unit switches between the first control and the second control. An actuator drive device according to any one of configurations 1 to 5, characterized by the above. (Composition 7) The control unit sets the duty cycle of the pulse widths of the first and second pulses to within 4 to 35% at the timing of switching between the first and second controls. The actuator drive device according to configuration 6, characterized by the features described above. (Composition 8) In the first control, the control unit sets the first pulse and the second pulse such that the timing of the pulse center of the first pulse falls within the pulse width of the second pulse. In the second control, the control unit sets the first pulse and the second pulse such that the timing of the pulse center of the second pulse falls within the pulse width of the first pulse. An actuator drive device according to any one of configurations 1 to 7, characterized by the above. (Composition 9) The actuator drive device according to any one of configurations 1 to 8, characterized in that the control unit sets the duty cycle of the pulse width of the second pulse to within 4 to 35% in the first control. (Composition 10) The control unit sets the first pulse and the second pulse such that the timing of the center of the first pulse and the timing of the center of the second pulse overlap in at least one of the first control and the second control. An actuator drive device according to any one of configurations 1 to 9, characterized by the above. (Composition 11) The control unit is capable of switching between the first pulse and the second pulse, which are set to the first voltage and the second voltage, respectively. An actuator drive device according to any one of configurations 1 to 10, characterized by the above. (Composition 12) The control unit switches the first pulse and the second pulse at a timing when the pulse width of the first pulse and the pulse width of the second pulse are equal. The actuator drive device according to configuration 11, characterized by the features described above. (Composition 13) A first output unit that outputs the first voltage applied to the first input terminal, A second output unit that outputs the second voltage applied to the second input terminal, An actuator drive device according to any one of configurations 1 to 12, characterized by having the following features. (Composition 14) It has a filter circuit, The first output unit outputs the first voltage to the first input terminal via the filter circuit. The second output section outputs the second voltage to the second input terminal via the filter circuit. The actuator drive device according to configuration 13, characterized by the above. (Composition 15) The filter circuit is a circuit having an inductor. The actuator drive device according to configuration 14, characterized by the features described above. (Composition 16) A first duty cycle setting unit sets the duty cycle of the first voltage output from the first output unit, A second duty cycle setting unit sets the duty cycle of the second voltage output from the second output unit. An actuator drive device according to any one of configurations 13 to 15, characterized by having the following features. (Composition 17) The actuator drive device according to any one of configurations 13 to 16, characterized by having a phase difference setting unit for setting the phase difference between the first voltage output from the first output unit and the second voltage output from the second output unit. (Composition 18) A device comprising an actuator drive device according to any one of configurations 1 to 17, and an element, wherein the actuator is configured to allow the element to move. (Composition 19) A device comprising an actuator drive device as described in any one of configurations 1 to 17, and an image sensor, wherein the actuator is configured to move the image sensor. (Method 20) A control method for an actuator drive device having a first input terminal to which a first voltage is applied and a second input terminal to which a second voltage is applied, and having a drive coil that generates a driving force to drive an actuator by applying the first voltage and the second voltage, One of the first voltage and the second voltage is set to be the first pulse and the other to be the second pulse. A first control that modulates the pulse width of one of the first and second pulses by a larger change than the change in the pulse width of the other pulse, such that the pulse width of the on-time of the second pulse falls within the pulse width of the on-time of the first pulse. A second control that modulates the pulse width of one of the first and second pulses by a larger change than the change in the pulse width of the other pulse, such that the pulse width of the on-time of the first pulse falls within the pulse width of the on-time of the second pulse. Do at least one of the following: A control method for an actuator drive device, characterized by the following: [Explanation of Symbols]

[0096] 100 Actuator drive device 110 Drive Circuit 111 Drive coil 112 First Input Terminal 113 Second input terminal 114 First Output Section 115 Second Output Section 116 First Duty Cycle Setting Unit 117 Second duty cycle setting section 118 Phase difference setting section 200 Actuators 210 Moving parts 211 Image sensor 300 filter circuit 301 Inductor 302 Capacitor 400 Image stabilization mechanism 410 Magnetic Sensor

Claims

1. A drive coil having a first input terminal to which a first voltage signal is applied and a second input terminal to which a second voltage signal is applied, and which generates a driving force to drive an actuator upon application of the first voltage signal and the second voltage signal, It comprises a control unit that controls the first voltage signal and the second voltage signal, The control unit, The first voltage signal is set to the first pulse, and the second voltage signal is set to the second pulse synchronized with the first pulse. A first control is performed to modulate the pulse width of one of the first and second pulses by a larger change than the change in the pulse width of the other of the first and second pulses, so that the pulse width of the on-time of the second pulse falls within the pulse width of the on-time of the first pulse, and to control the coil drive voltage applied to the drive coil by the first voltage signal and the second voltage signal so that there are two pulses in one period of the first pulse. A second control is performed to modulate the pulse width of the other of the first and second pulses by a larger change than the change in the pulse width of one of the first and second pulses, so that the pulse width of the on-time of the first pulse falls within the pulse width of the on-time of the second pulse, and to control the coil drive voltage applied to the drive coil by the first voltage signal and the second voltage signal so that there are two pulses in one period of the second pulse. Switch between them to perform the action. An actuator drive device characterized by the following:

2. In the first control, the amount of change in the pulse width of the second pulse is within ±4% of the duty cycle that serves as the reference for the pulse width of the second pulse. The actuator drive device according to feature 1.

3. In the first control, the second pulse is a fixed pulse. The actuator drive device according to feature 2.

4. In the second control, the amount of change in the pulse width of the first pulse is within ±4% of the duty cycle that serves as the reference for the pulse width of the first pulse. The actuator drive device according to feature 2.

5. In the second control, the first pulse is a fixed pulse. The actuator drive device according to feature 4.

6. The two pulses in the first control are pulses that generate a driving force in the same direction in the drive coil. The actuator drive device according to any one of claims 1 to 5.

7. When the control unit switches between the first control and the second control, it sets the duty cycle of the pulse widths of the first pulse and the second pulse to within 4 to 35%. The actuator drive device according to feature 1.

8. In the first control, the control unit sets the first pulse and the second pulse such that the timing of the center of the first pulse falls within the pulse width of the second pulse. In the second control, the control unit sets the first pulse and the second pulse so that the timing of the pulse center of the second pulse falls within the pulse width of the first pulse. The actuator drive device according to any one of claims 1 to 5.

9. The actuator drive device according to any one of claims 1 to 5, characterized in that the control unit sets the duty cycle of the pulse width of the second pulse to within 4 to 35% in the first control.

10. The control unit sets the first pulse and the second pulse such that the timing of the center of the first pulse and the timing of the center of the second pulse overlap in at least one of the first control and the second control. The actuator drive device according to any one of claims 1 to 5.

11. The control unit is capable of switching the direction of the current flowing through the drive coil between the first control and the second control. The actuator drive device according to any one of claims 1 to 5.

12. The control unit switches between the first control and the second control at a timing when the pulse width of the first pulse and the pulse width of the second pulse are equal. The actuator drive device according to any one of claims 1 to 5.

13. A first output unit that outputs the first voltage signal applied to the first input terminal, A second output unit that outputs the second voltage signal applied to the second input terminal, An actuator drive device according to any one of claims 1 to 5, characterized by having the following features.

14. It has a filter circuit, The first output unit outputs the first voltage signal to the first input terminal via the filter circuit. The second output unit outputs the second voltage signal to the second input terminal via the filter circuit. The actuator drive device according to claim 13.

15. The filter circuit is a circuit having an inductor. The actuator drive device according to feature 14.

16. A first duty cycle setting unit sets the duty cycle of the first voltage signal output from the first output unit, A second duty cycle setting unit sets the duty cycle of the second voltage signal output from the second output unit. The actuator drive device according to claim 13, characterized by having the following features.

17. The actuator drive device according to claim 13, further comprising a phase difference setting unit for setting the phase difference between the first voltage signal output from the first output unit and the second voltage signal output from the second output unit.

18. A device comprising an actuator drive device according to any one of claims 1 to 5, and an element, wherein the actuator is configured to allow the element to move.

19. A device comprising an actuator drive device according to any one of claims 1 to 5, and an image sensor, wherein the actuator is configured to move the image sensor.

20. A control method for an actuator drive device having a first input terminal to which a first voltage signal is applied and a second input terminal to which a second voltage signal is applied, and having a drive coil that generates a driving force to drive the actuator by applying the first voltage signal and the second voltage signal, The first voltage signal is set to the first pulse, and the second voltage signal is set to the second pulse synchronized with the first pulse. A first control is performed to modulate the pulse width of one of the first and second pulses by a larger change than the change in the pulse width of the other of the first and second pulses, so that the pulse width of the on-time of the second pulse falls within the pulse width of the on-time of the first pulse, and to control the coil drive voltage applied to the drive coil by the first voltage signal and the second voltage signal so that there are two pulses in one period of the first pulse. A second control is performed to modulate the pulse width of the other of the first and second pulses by a larger change than the change in the pulse width of one of the first and second pulses, so that the pulse width of the on-time of the first pulse falls within the pulse width of the on-time of the second pulse, and to control the coil drive voltage applied to the drive coil by the first voltage signal and the second voltage signal so that there are two pulses in one period of the second pulse. Switch between them to perform the action. A control method for an actuator drive device, characterized by the following:

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