Actuator driver, camera module using the same and electronic apparatus

Abstract

To provide an actuator driver capable of driving an actuator having a plurality of voice coils.SOLUTION: An actuator 120 includes: a movable element 124 including a magnet 122; and a plurality of voice coils L1-L3 arranged in a movable direction of the movable element 124. A controller 230 generates a control signal ctrl. A drive part 220 drives the plurality of voice coils L1-L3 according to the control signal ctrl. The drive part 220 includes a correction unit COMPi corresponding to a voice coil Li and configured to correct the control signal ctrl according to a position detection signal PFB showing a position of the movable element 124. A driver DRi drives the corresponding voice coil Li according to an output ctrl' of a corresponding correction unit COMPi.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to an actuator driver and a camera module using the same. [Background technology]

[0002] In recent years, optical image stabilizers (OIS) have been increasingly adopted in camera modules installed in electronic devices such as smartphones. A camera module with optical image stabilization includes an image sensor, a lens (called an image stabilization lens) that can move within the XY plane parallel to the imaging surface of the image sensor, an actuator that positions the lens, and an actuator driver that controls the actuator. When a shake is detected by a shake detection means such as a gyro sensor, the actuator driver drives the actuator to shift the lens so as to offset the shake. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-138984 Summary of the Invention [Problem to be solved by the invention]

[0004] In a MM (Moving Magnet) type voice coil motor, in order to increase the stroke length, a plurality of voice coils are arranged along the moving direction of a mover having a magnet.

[0005] In an actuator with a long stroke length, when the same amount of drive current is supplied, the magnitude or direction of the thrust generated by one voice coil changes depending on the position of the mover. Since the thrust of the actuator is the sum of the thrusts generated by multiple voice coils, the thrust fluctuates depending on the position of the mover.

[0006] The present disclosure has been made in this context, and one of its exemplary purposes is to provide an actuator driver that reduces the position dependency of the thrust force. [Means for solving the problem]

[0007] One aspect of the present disclosure relates to an actuator driver that drives an actuator that positions a movable part. The actuator is a moving magnet (MM) type voice coil motor that includes a mover including a magnet and multiple voice coils arranged along the moving direction of the mover. The actuator driver includes a drive unit that drives the multiple voice coils in response to a control signal. The drive unit includes multiple correction units corresponding to the multiple voice coils, each correcting the control signal in response to a position detection signal indicating the position of the mover, and multiple drivers corresponding to the multiple voice coils, each driving a corresponding voice coil in response to the output of the corresponding correction unit.

[0008] Any combination of the above elements, or mutual substitution of elements or expressions between methods, devices, systems, etc., are also valid aspects of the present invention or the present disclosure. Furthermore, the description in this section (Means for Solving the Problems) does not explain all essential features of the present invention, and therefore, subcombinations of the described features may also constitute the present invention. [Effects of the Invention]

[0009] According to the present disclosure, the position of a movable part can be detected when combined with an actuator having a long stroke length. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram of a camera module with an image stabilization function. [Figure 2] FIG. 2 is a block diagram of the actuator driver. [Figure 3] FIG. 3 is a block diagram of an actuator driver according to the embodiment. [Figure 4] FIG. 4 is a diagram showing the thrust generated by each of the multiple voice coils. [Figure 5] FIG. 5 is a diagram illustrating correction of the propulsive force by the drive unit. [Figure 6] FIG. 6 is a block diagram illustrating an example of the configuration of the correction unit. [Figure 7] FIG. 7 is a block diagram of an actuator driver according to the first modification. DETAILED DESCRIPTION OF THE INVENTION

[0011] (Outline of the embodiment) A summary of some exemplary embodiments of the present disclosure is provided. This summary is intended to provide a simplified overview of some concepts of one or more embodiments in order to provide a basic understanding of the embodiments as a prelude to the more detailed description that follows. It is not intended to limit the scope of the invention or disclosure. This summary is not an exhaustive overview of all possible embodiments, and is not intended to identify key elements of all embodiments or to delineate the scope of some or all aspects. For convenience, the term "one embodiment" may refer to one embodiment (example or variant) or multiple embodiments (examples or variants) disclosed herein.

[0012] An actuator driver according to one embodiment drives an actuator that positions a movable part. The actuator is a moving magnet (MM) type voice coil motor that includes a mover including a magnet and multiple voice coils arranged along the moving direction of the mover. The actuator driver includes a drive unit that drives the multiple voice coils in response to a control signal. The drive unit includes multiple correction units corresponding to the multiple voice coils, each correcting the control signal in response to a position detection signal indicating the position of the mover, and multiple drivers corresponding to the multiple voice coils, each driving a corresponding voice coil in response to the output of the corresponding correction unit.

[0013] In this configuration, a correction unit is provided to correct the control signal so that the thrust generated by the multiple voice coils does not flow in the opposite direction, thereby suppressing fluctuations in thrust depending on the position of the mover.

[0014] In one embodiment, each of the multiple correction units may generate a correction gain according to the position detection signal and multiply the control signal by the correction gain.

[0015] In one embodiment, the actuator driver may further include a servo controller that generates a control signal so that the position detection signal approaches a target value.

[0016] In one embodiment, the servo controller may include an error detector that generates an error between a target value and a position detection signal, and a proportional-integral controller that receives the error.

[0017] In one embodiment, the actuator driver may be monolithically integrated on a single semiconductor substrate. "Monolithic integration" includes cases where all of the circuit components are formed on a semiconductor substrate, or where the main circuit components are monolithically integrated, and some resistors and capacitors for adjusting circuit constants may be provided outside the semiconductor substrate. By integrating the circuit on a single chip, the circuit area can be reduced and the characteristics of the circuit elements can be maintained uniform.

[0018] A camera module according to one embodiment may include an image sensor, an image stabilization mechanism provided on the incident light path to the image sensor, an actuator that positions a movable part of the image stabilization mechanism, and any of the actuator drivers described above.

[0019] (Embodiment) Preferred embodiments will be described below with reference to the drawings. The same or equivalent components, parts, and processes shown in each drawing will be given the same reference numerals, and redundant explanations will be omitted as appropriate. Furthermore, the embodiments are examples and do not limit the disclosure and invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the disclosure and invention.

[0020] In this specification, "a state in which component A is connected to component B" includes not only a case in which component A and component B are directly physically connected to each other, but also a case in which component A and component B are indirectly connected to each other via other components that do not substantially affect the electrical connection between them or that do not impair the function or effect achieved by their connection.

[0021] Similarly, "a state in which component C is provided between component A and component B" includes not only cases in which components A and C, or components B and C, are directly connected, but also cases in which they are indirectly connected via other components that do not substantially affect the electrical connection state between them or impair the functions or effects achieved by their combination.

[0022] 1 is a block diagram of a camera module with an image stabilization function. Camera module 100 includes an image sensor 102, an image stabilization lens 104, a first actuator 106_1, a second actuator 106_2, an actuator driver 200, position detection elements 110_1 and 110_2, a shake detection unit 112, and a CPU (Central Processing Unit) 114. Camera module 100 also includes an autofocus lens, an actuator, and the like, but these are omitted from FIG. 1.

[0023] For ease of understanding, the optical axis direction of image stabilization lens 104 is taken as the Z axis. Furthermore, when camera module 100 is in the position shown in Figure 1, the left-right direction is taken as the X axis, and the up-down direction is taken as the Y axis. The X axis is also referred to as the first axis, and the Y axis is also referred to as the second axis.

[0024] Image stabilization lens 104 is disposed on the optical path of light incident on image sensor 102. Image sensor 102 is a CMOS sensor or a CCD, and captures an image that has passed through image stabilization lens 104.

[0025] The image stabilization lens 104 is supported so as to be movable in the X and Y directions in a plane (XY plane) parallel to the imaging surface of the image sensor 102. The first actuator 106_1 positions the movable part 105 including the image stabilization lens 104 in the first axis (X axis) direction, and the second actuator 106_2 positions the movable part 105 in the second axis (Y axis) direction. The first actuator 106_1 and the second actuator 106_2 are linear actuators, and for example, voice coil motors are used. The movable part 105 including the image stabilization lens 104 has a mechanically restricted range of movement in both the first axis direction and the second axis direction. The ends of the movable range are called mechanical ends. There are mechanical ends in both the positive and negative directions in the first axis direction, and there are mechanical ends in both the positive and negative directions in the second axis direction.

[0026] The shake detection means 112 detects the shake of the camera module 100 and generates a shake detection signal S1 indicative of the shake. The shake detection means 112 is, for example, a gyro sensor, and detects the angular velocity ω of the camera module 100 around the X axis. X , angular velocity around the Y axis ω Y , angular velocity around the Z axis ω Z By controlling the position of the image stabilization lens 104 in the X-axis direction, it is possible to correct rotation (shake) around the Y-axis, and by controlling the position of the image stabilization lens 104 in the Y-axis direction, it is possible to correct rotation (shake) around the X-axis. The shake detection signal S1 is a signal obtained by detecting angular velocities ω X ,ω Y Includes:

[0027] Based on the shake detection signal S1 detected by the shake detection means 112, the actuator driver 200 generates a target code (position command) indicating a target value for displacement of the image stabilization lens 104 so as to cancel out the shake. Based on the target code generated internally, the actuator driver 200 generates drive signals S2_1 and S2_2 for the first actuator 106_1 and the second actuator 106_2, respectively. The actuator 106_i (i=1, 2) positions the image stabilization lens 104 in accordance with the corresponding drive signal S2_i.

[0028] In image stabilization, feedback control (closed loop control) is employed because it is necessary to accurately position the image stabilization lens 104. The position detection elements 110_1 and 110_2 each detect the position (displacement) P of the image stabilization lens 104 in the first axis direction. X and the position (displacement) in the second axis direction P Y The position detection element 110 generates position detection signals S3_1 and S3_2 indicating the position of the object. The position detection element 110 may be, for example, a Hall sensor.

[0029] The actuator driver 200 drives the first actuator 106_1 and the second actuator 106_2 so that camera shake is corrected. Specifically, in the first mode, the actuator driver 200 detects the position P of the camera shake correction lens 104 indicated by the first position detection signal S3_1. X is the target position P indicated by the target code. X(REF) Similarly, the actuator driver 200 feedback-controls the drive signal S2_1 so that the position P of the image stabilization lens 104 indicated by the second position detection signal S3_2 coincides with the position P Y is the target position P indicated by the target code. Y(REF) The drive signal S2_2 is feedback-controlled so that it coincides with the above.

[0030] The above is the overall configuration of the camera module 100. Next, the actuator driver 200 will be described.

[0031] 2 is a block diagram of the actuator driver 200. The actuator driver 200 includes a control unit 210, a first driving unit 220_1, and a second driving unit 220_2. The gyro sensor 112A is the shake detection means 112 in FIG. 1, and detects the angular velocity of the camera module 100.

[0032] The control unit 210 includes a position command generating unit 212, a first servo controller 230_1, a second servo controller 230_2, a first position detecting unit 240_1, and a second position detecting unit 240_2.

[0033] In the first mode, the position command generator 212 receives the shake detection signal S1 generated by the gyro sensor 112A, and generates a position command X indicating the position of the image stabilization lens 104 that can cancel out the shake for each of the X and Y axes. REF ,Y REF For example, the position command generator 212 generates an angular velocity ω X is integrated and multiplied by a predetermined gain to obtain the position command X REF Similarly, the position command generator 212 generates an angular velocity ω Y is integrated and multiplied by a predetermined gain to obtain the position command Y REF Generate.

[0034] The position detection signal S3_1 generated by the position detection element 110_1 is input to the first position detection section 240_1. The first position detection section 240_1 generates a feedback signal X FB Generate.

[0035] Similarly, the position detection signal S3_2 generated by the position detection element 110_2 is input to the second position detection section 240_2. The second position detection section 240_2 generates a feedback signal Y FB Generates a feedback signal X FB ,Y FBindicate the positions of the movable part 105 in the X direction and the Y direction (X coordinate, Y coordinate), respectively.

[0036] The first servo controller 230_1 receives a feedback signal X FB and position command X REF The first driving unit 220_1 generates a control signal S4_1 so that the error approaches zero. The first driving unit 220_1 generates a driving signal S2_1 according to the control signal S4_1. The control signal S4_1 is, for example, a current command, and the first driving unit 220_1 supplies a driving current of a current amount according to the control signal S4_1 to the first actuator 106_1. The control signal S4_1 may also be considered as a torque command.

[0037] Similarly, the second servo controller 230_2 converts the position detection signal S3_2 generated by the position detection element 110_2 into a feedback signal Y indicating the Y coordinate of the movable part 105. FB The second servo controller 230_2 receives the feedback signal Y FB and position command Y REF The second driving unit 220_2 generates a control signal S4_2 so that the error approaches zero. The second driving unit 220_2 generates a driving signal S2_2 according to the control signal S4_2.

[0038] In FIG. 2, the configuration (220_1, 230_1, 240_1) of the actuator driver 200 corresponding to the actuator 106_1 is the same as the configuration (220_2, 230_2, 240_2) of the actuator driver 200 corresponding to the actuator 106_2.

[0039] Fig. 3 is a block diagram of an actuator driver 200 according to an embodiment. A servo controller 230 in Fig. 3 corresponds to the first servo controller 230_1 or the second servo controller 230_2 in Fig. 2. P in Fig. 3 is X or Y in Fig. 2. A driving unit 220 in Fig. 3 corresponds to the first driving unit 220_1 or the second driving unit 220_2 in Fig. 2. A position detecting unit 240 in Fig. 3 corresponds to the first position detecting unit 240_1 or the second position detecting unit 240_2 in Fig. 2. An actuator 120 in Fig. 3 corresponds to the actuator 106 in Fig. 2.

[0040] Actuator 120 is a voice coil motor, and includes a magnet 122 and multiple (three in this example) voice coils L1 to L3. Magnet 122 is attached to a mover 124. The multiple voice coils L1 to L3 are provided along the direction in which mover 124 moves.

[0041] The position detection unit 240 generates a position detection signal (feedback signal) P based on the output of the position detection element 110. FB For example, the position detection unit 240 includes an A / D converter that converts the output signal of the position detection element 110 into a digital signal. The position detection unit 240 may further include a correction unit that corrects the position detection signal. FB is fed back to the servo controller 230.

[0042] The servo controller 230 includes an error detector 232 and a compensator 234. The error detector 232 detects the position command P REF and a feedback signal P indicating the position of the movable part 105. FB The error detector 232 generates an error err between the input signal and the output signal. The error detector 232 can be configured with a subtractor.

[0043] The compensator 234 generates a control signal ctrl in accordance with the error err. The compensator 234 is also referred to as a servo filter. The compensator 234 may be, for example, a PI (proportional-integral) controller, and may generate the control signal ctrl by adding a value obtained by multiplying the error err by a proportional gain kp and a value obtained by multiplying the integral value of the error err by an integral gain ki. The compensator 234 may also be a PID (proportional-integral-derivative) controller.

[0044] The driving section 220 includes a plurality of correction sections COMP1 to COMP3 and a plurality of drivers DR1 to DR3. The plurality of correction sections COMP1 to COMP3 and the plurality of drivers DR1 to DR3 correspond to a plurality of voice coils L1 to L3.

[0045] A control signal ctrl is supplied to the plurality of correction units COMP1 to COMP3. Each correction unit COMPi (i=1, 2, 3) outputs a position detection signal P FB The control signal ctrl is corrected according to the voice coil. The correction characteristics are different for each voice coil. The corrected control signal ctrli is supplied to the corresponding driver DRi.

[0046] In this embodiment, the correction unit COMPi corrects the position detection signal P FB Then, the corrector COMPi generates a correction gain gi according to the control signal ctrl. The corrector COMPi then multiplies the control signal ctrl by the correction gain gi to generate a control signal ctrli. ctrli=gi×ctrl

[0047] The driver DRi drives the corresponding voice coil Li based on the corresponding corrected control signal ctrli.

[0048] The above is the configuration of the actuator driver 200. Next, the operation thereof will be described.

[0049] First, the operation when the control signal ctrl is not corrected will be described.

[0050] 4 is a diagram showing thrusts F1 to F3 generated by each of the voice coils L1 to L3. The thrust Fi is the thrust obtained when the uncorrected control signal ctrl is input to the driver DRi. The horizontal axis represents the position P of the mover.

[0051] The thrust of each voice coil Li is constant within a certain range Ai, but when it deviates from the range Ai, it decreases and eventually reverses direction. The range Ai is called the stable output region. Figure 3 shows the composite thrust F, which is the sum of multiple thrusts F1 to F3. SUM The resultant driving force F SUM is position-dependent, which is undesirable because the tracking ability and stability vary depending on the position. As will be described below, the actuator driver 200 according to the embodiment corrects the control signal ctrl so that a constant thrust is obtained regardless of the position, that is, so that the linear dependency of the resultant thrust is reduced.

[0052] FIG. 5 is a diagram illustrating the correction of thrust by the driving unit 220. The upper part of FIG. 5 shows thrusts F1 to F3 without correction. The middle part of FIG. 5 shows correction gains g1 to g3. The lower part of FIG. 5 shows the thrusts F1' to F3' after correction and the resultant thrust F, which is their sum. SUM '=F1'+F2'+F3' is shown.

[0053] In this example, the correction gain gi of the i-th correction unit COMPi is set to a constant value in the stable output region Ai where a constant thrust is obtained, and to 0 outside the stable output region Ai. The corrected thrust Fi' is the thrust Fi before correction multiplied by the correction gain gi.

[0054] The resultant thrust F is the sum of the corrected thrusts F1' to F3'. SUM is substantially constant regardless of the position P. For ease of understanding and simplicity of explanation, the resultant thrust F SUM is assumed to be constant regardless of position, but the present disclosure is not limited to this. SUMSince it is difficult to completely eliminate the position dependency of the resultant thrust F without the correction in Figure 4, SUM Compared to the corrected resultant thrust F SUM It is sufficient if the position dependency of ' is small.

[0055] It will be understood by those skilled in the art that the position dependence of the thrust forces F1 to F1 before correction shown in FIG. 5 is an example and will vary depending on the structure of the actuator 120. Therefore, the correction gains g1 to g3 are not limited to those shown in FIG. 5, and the corrected composite thrust force F SUM It is sufficient to set it so that the position dependency of ' becomes small.

[0056] 6 is a block diagram showing an example of the configuration of the correction units COMP1 to COMP3. The correction unit COMPi (i=1 to 3) includes a gain circuit 222 and a look-up table 224. The look-up table 224 of the correction unit COMPi stores the position detection signal P FB The correspondence between the current position detection signal P FB The correction gain gi corresponding to this is read out and supplied to the gain circuit 222. The gain circuit 222 multiplies the control signal ctrl by the correction gain gi, and outputs the corrected control signal ctrli.

[0057] Position detection signal P FB The relationship between the correction gain gi and the correction gain gi may be expressed as a function, and the correction gain gi may be calculated by calculation.

[0058] The above-described embodiment is merely an example, and it will be understood by those skilled in the art that various modifications are possible in the combination of the components and the processing steps. Such modifications will be described below.

[0059] (Variation 1) In the embodiment, a closed-loop position control system has been described, but the present disclosure is not limited to this and can also be applied to an open-loop position control system.

[0060] 7 is a block diagram of an actuator driver 200A according to Modification 1. In the actuator driver 200A, a controller 230A is provided instead of the servo controller 230 in FIG. 3. The controller 230A outputs a position command P REF is supplied to the driver 220 as a control signal ctrl.

[0061] Generally, an open-loop position control system does not require a position detection element 110, but in this modification 1, a position detection element 110 is provided to determine the correction gains g1 to g3. According to this actuator driver 200A, the position dependency of the resultant thrust can be reduced.

[0062] (Variation 2) In the embodiment, a camera module 100 having an image stabilization mechanism using an image stabilization lens 104 has been described, but the image stabilization mechanism is not limited to one using lens shift, and the present disclosure can also be applied to an image stabilization mechanism using a prism.

[0063] (Variation 3) In the embodiment, a position control system for an image stabilization mechanism has been described, but the present disclosure is not limited to this and can also be applied to a position control system for autofocus.

[0064] (Variation 4) The number of voice coils is not limited to three, but may be two, four, or more.

[0065] Although the embodiments of the present disclosure have been described using specific terms, this description is merely an example to facilitate understanding and does not limit the scope of the present disclosure or the claims. The scope of the present invention is defined by the claims, and therefore, embodiments, examples, and modifications not described herein are also included in the scope of the present invention.

[0066] (Addendum) The embodiment according to the present disclosure can be understood as follows. (Item 1) An actuator driver that drives an actuator that positions a movable part, the actuator is a MM (Moving Magnet) type voice coil motor including a mover including a magnet and a plurality of voice coils arranged along the moving direction of the mover, The actuator driver a driver that drives the voice coils in response to a control signal; Equipped with The drive unit is a plurality of correction units corresponding to the plurality of voice coils, each correcting the control signal in response to a position detection signal indicating a position of the mover; a plurality of drivers corresponding to the plurality of voice coils, each of which drives a corresponding voice coil in accordance with an output of a corresponding correction unit; An actuator driver comprising: (Item 2) 2. The actuator driver according to item 1, wherein each of the plurality of correction units generates a correction gain according to the position detection signal and multiplies the control signal by the correction gain. (Item 3) 3. The actuator driver according to item 1 or 2, further comprising a servo controller that generates the control signal so that the position detection signal approaches a target value. (Item 4) The servo controller an error detector that generates an error between the target value and the position detection signal; a proportional-integral controller that receives the error; Item 4. The actuator driver of item 3, comprising: (Item 5) 5. The actuator driver according to any one of items 1 to 4, which is monolithically integrated on a single semiconductor substrate. (Item 6) An image sensor; a camera shake correction mechanism provided on an incident light path to the image sensor; an actuator for positioning a movable part of the image stabilization mechanism; An actuator driver according to any one of items 1 to 4; A camera module comprising: (Item 7) Item 7. An electronic device comprising the camera module according to item 6. [Explanation of symbols]

[0067] L1, L2, L3 voice coils 100 Camera Module 102 Image Sensor 104 Image Stabilizer Lens 105 Moving parts 106 Actuator 110 Position detection element 112 Shake detection means 112A Gyro Sensor 114 CPU 120 Actuator 122 Magnet 124 Mover 200 Actuator Driver 210 Control Unit 212 Position command generation section 220 Drive Unit 220_1 First drive unit 220_2 Second drive unit COMPi Correction section DRi Driver 222 Gain Circuit 224 Lookup Table 230_1 First servo controller 230_2 Second servo controller 230 Servo Controller 232 Error Detector 234 Compensator 240 Position detection unit 240_1 First position detection unit 240_2 Second position detection unit

Claims

1. An actuator driver that drives an actuator that positions a movable part, the actuator is a moving magnet (MM) type voice coil motor including a mover including a magnet and a plurality of voice coils arranged along the moving direction of the mover, The actuator driver a driver that drives the voice coils in response to a control signal; Equipped with The drive unit is a plurality of correction units corresponding to the plurality of voice coils, each correcting the control signal in response to a position detection signal indicating a position of the mover; a plurality of drivers corresponding to the plurality of voice coils, each of which drives a corresponding voice coil in accordance with an output of a corresponding correction unit; An actuator driver comprising:

2. 2. The actuator driver according to claim 1, wherein each of the plurality of correction sections generates a correction gain corresponding to the position detection signal, and multiplies the control signal by the correction gain.

3. 3. The actuator driver according to claim 1, further comprising a servo controller that generates the control signal so that the position detection signal approaches a target value.

4. The servo controller an error detector that generates an error between the target value and the position detection signal; a proportional-integral controller that receives the error; 4. The actuator driver of claim 3, comprising:

5. 3. The actuator driver according to claim 1, wherein the actuator driver is monolithically integrated on a single semiconductor substrate.

6. An image sensor; a camera shake correction mechanism provided on an incident light path to the image sensor; an actuator for positioning a movable part of the image stabilization mechanism; an actuator driver according to claim 1 or 2; A camera module comprising:

7. An electronic device comprising the camera module according to claim 6.

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