WO2023238672A1

WO2023238672A1 - Actuator driver, and camera module and electronic device using same

Info

Publication number: WO2023238672A1
Application number: PCT/JP2023/019374
Authority: WO
Inventors: 淳前出
Original assignee: ローム株式会社
Priority date: 2022-06-06
Filing date: 2023-05-24
Publication date: 2023-12-14

Abstract

An actuator 120 includes a movable element 124 including a magnet 122, and a plurality of voice coils L1-L3 arranged along the movement direction of the movable element 124. A controller 230 generates a control signal ctrl. A drive unit 220 drives the plurality of voice coils L1-L3 according to the control signal ctrl. A correction unit COMPi of the drive unit 220 corrects the control signal ctrl in accordance with a position detection signal PFB, which corresponds to a voice coil Li and indicates the position of the movable element 124. A driver DRi drives the corresponding voice coil Li according to the output ctrl' of the corresponding correction unit COMPi.

Description

Actuator drivers and camera modules and electronic devices using them

The present disclosure relates to an actuator driver and a camera module using the same.

In recent years, optical image stabilizer (OIS) has 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 movable in an XY plane parallel to the imaging surface of the image sensor (referred to as an image stabilization lens), an actuator that positions the lens, and an actuator driver that controls the actuator. Equipped with. 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 that the shake is canceled out.

Japanese Patent Application Publication No. 2018-138984

In an MM (Moving Magnet) type voice coil motor, a plurality of voice coils are arranged along the movable direction of a mover having a magnet in order to lengthen the stroke length.

In an actuator with a long stroke length, when the same amount of drive current is supplied, the magnitude or direction of the propulsive force generated by one voice coil changes depending on the position of the mover. Since the propulsive force of the actuator is the sum of propulsive forces generated by a plurality of voice coils, the propulsive force varies depending on the position of the movable element.

The present disclosure has been made under such circumstances, and one of its exemplary objectives is to provide an actuator driver that reduces the position dependence of propulsive force.

An aspect of the present disclosure relates to an actuator driver that drives an actuator that positions a movable part. The actuator is an MM (Moving Magnet) type voice coil motor that includes a mover including a magnet and a plurality of voice coils arranged along the moving direction of the mover. The actuator driver includes a drive section that drives the plurality of voice coils according to a control signal. The drive section corresponds to a plurality of voice coils, each of which corrects a control signal according to a position detection signal indicating the position of the movable element, and a plurality of voice coils, each of which , and a plurality of drivers that drive corresponding voice coils according to outputs of corresponding correction sections.

Note that arbitrary combinations of the above components, and mutual substitution of components and expressions among methods, devices, systems, etc., are also effective as aspects of the present invention or the present disclosure. Furthermore, the description in this section (Means for Solving the Problems) does not describe all essential features of the present invention, and therefore, subcombinations of the described features may also constitute the present invention. .

According to the present disclosure, the position of the movable part can be detected in combination with an actuator having a long stroke length.

FIG. 1 is a block diagram of a camera module equipped with an image stabilization function. FIG. 2 is a block diagram of the actuator driver. FIG. 3 is a block diagram of the actuator driver according to the embodiment. FIG. 4 is a diagram showing propulsive forces generated by each of a plurality of voice coils. FIG. 5 is a diagram illustrating correction of the propulsive force by the drive unit. FIG. 6 is a block diagram showing an example of the configuration of the correction section. FIG. 7 is a block diagram of an actuator driver according to Modification 1.

(Summary of embodiment)
1 provides an overview of some example embodiments of the present disclosure. This Summary is intended to provide a simplified description of some concepts of one or more embodiments in order to provide a basic understanding of the embodiments and as a prelude to the more detailed description that is presented later. It does not limit the size. 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 any or all aspects. For convenience, "one embodiment" may be used to refer to one embodiment (example or modification) or multiple embodiments (examples or modifications) disclosed in this specification.

An actuator driver according to one embodiment drives an actuator that positions a movable part. The actuator is an MM (Moving Magnet) type voice coil motor that includes a mover including a magnet and a plurality of voice coils arranged along the moving direction of the mover. The actuator driver includes a drive section that drives the plurality of voice coils according to a control signal. The drive section corresponds to a plurality of voice coils, each of which corrects a control signal according to a position detection signal indicating the position of the movable element, and a plurality of voice coils, each of which , a plurality of drivers that drive corresponding voice coils according to outputs of corresponding correction sections.

In this configuration, by providing a correction unit and correcting the control signal so that the propulsive forces generated by the plurality of voice coils do not go in opposite directions, it is possible to suppress fluctuations in the propulsive force depending on the position of the movable element.

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

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.

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

In one embodiment, the actuator driver may be monolithically integrated on one semiconductor substrate. "Integration" includes cases where all of the circuit components are formed on a semiconductor substrate, cases where the main components of the circuit are integrated, and some of the components are integrated to adjust the circuit constants. A resistor, a capacitor, etc. may be provided outside the semiconductor substrate. By integrating circuits on one chip, the circuit area can be reduced and the characteristics of circuit elements can be kept uniform.

A camera module according to an embodiment includes an image sensor, an image stabilization mechanism provided on an incident optical path to the image sensor, an actuator that positions a movable part of the image stabilization mechanism, and one of the actuator drivers described above. and may also be provided.

(Embodiment)
Hereinafter, preferred embodiments will be described with reference to the drawings. Identical or equivalent components, members, and processes shown in each drawing are designated by the same reference numerals, and redundant explanations will be omitted as appropriate. Furthermore, the embodiments are illustrative rather than limiting the disclosure and invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the disclosure and invention.

In this specification, "a state in which member A is connected to member B" refers to not only a case where member A and member B are physically directly connected, but also a state in which member A and member B are electrically connected. This also includes cases in which they are indirectly connected via other members that do not substantially affect the connection state or impair the functions and effects achieved by their combination.

Similarly, "a state in which member C is provided between member A and member B" refers to the case where member A and member C or member B and member C are directly connected, This also includes cases in which they are indirectly connected via other members that do not substantially affect the connection state or impair the functions and effects achieved by their combination.

FIG. 1 is a block diagram of a camera module equipped with an image stabilization function. The 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, 110_2, a shake detection means 112, and a CPU (Central Processing Unit) 114. . The camera module 100 also includes an autofocus lens, an actuator, etc., but these are omitted in FIG.

For ease of understanding, the optical axis direction of the camera shake correction lens 104 is assumed to be the Z-axis. Further, when the camera module 100 is in the attitude shown in FIG. 1, the horizontal direction is assumed to be the X axis, and the vertical direction is assumed to be 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.

The camera shake correction lens 104 is placed on the optical path of light incident on the image sensor 102. The image sensor 102 is a CMOS sensor or CCD, and captures an image transmitted through the camera shake correction lens 104.

The camera shake correction lens 104 is supported so as to be movable in the X direction and the Y direction in a plane parallel to the imaging surface of the image sensor 102 (XY plane). The first actuator 106_1 positions the movable part 105 including the camera shake correction 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 portion 105 including the camera shake correction lens 104 has a movable range mechanically restricted in each of the first axis direction and the second axis direction. The end of the movable range is called the mechanical end. Mechanical ends exist in the positive direction and negative direction in the first axis direction, and mechanical ends exist in the positive direction and the negative direction in the second axis direction as well.

The shake detection means 112 detects shake of the camera module 100 and generates a shake detection signal S1 indicating the shake. The shake detection means 112 is, for example, a gyro sensor, and detects the angular velocity ω _X around the X axis, the angular velocity ω _Y around the Y axis, and the angular velocity ω _Z around the Z axis of the camera module 100. By controlling the position of the image stabilization lens 104 in the X-axis direction, rotation (shake) around the Y-axis can be corrected, and by controlling the position of the image stabilization lens 104 in the Y-axis direction, the Rotation (shake) around the axis can be corrected. The shake detection signal S1 includes angular velocities ω _X and ω _Y of at least two axes.

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 of the displacement of the camera shake correction lens 104 so that the shake is canceled out. 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, based on internally generated target codes. The actuator 106_i (i=1, 2) positions the camera shake correction lens 104 according to the corresponding drive signal S2_i.

In camera shake correction, since it is necessary to accurately position the camera shake correction lens 104, feedback control (closed loop control) is employed. The position detection elements 110_1 and 110_2 respectively generate position detection signals S3_1 and _{S3_2} indicating the position (displacement amount) _PX in the first axis direction and the position (displacement amount) PY in the second axis direction of the camera shake correction lens 104. do. For example, a Hall sensor or the like can be used as the position detection element 110.

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 operates so that the position _PX of the camera shake correction lens 104 indicated by the first position detection signal S3_1 matches the target position PX _(REF) indicated by the target code. The drive signal S2_1 is feedback-controlled. Similarly, the actuator driver 200 performs feedback control on the drive signal S2_2 so that the position P _Y of the camera shake correction lens 104 indicated by the second position detection signal S3_2 matches the target position P _{Y (REF)} indicated by the target code. do.

The above is the overall configuration of the camera module 100. Next, the actuator driver 200 will be explained.

FIG. 2 is a block diagram of the actuator driver 200. The actuator driver 200 includes a control section 210, a first drive section 220_1, and a second drive section 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.

The control unit 210 includes a position command generation unit 212, a first servo controller 230_1, a second servo controller 230_2, a first position detection unit 240_1, and a second position detection unit 240_2.

In the first mode, the position command generation unit 212 receives the shake detection signal S1 generated by the gyro sensor 112A, and generates a position indicating the position of the camera shake correction lens 104 that can offset the shake for each of the X-axis and Y-axis. Generate commands X _REF and Y _REF . For example, the position command generation unit 212 generates the position command X _REF by integrating the angular velocity ω _X around the X-axis and multiplying it by a predetermined gain. Similarly, the position command generation unit 212 generates the position command Y _REF by integrating the angular velocity ω _Y around the Y-axis and multiplying it by a predetermined gain.

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 unit 240_1 generates a feedback signal _XFB indicating the position of the movable element of the actuator 106_1 based on the position detection signal S3_1.

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 unit 240_2 generates a feedback signal _YFB indicating the position of the movable element of the actuator 106_2 based on the position detection signal S3_2. Feedback signals X _FB and Y _FB indicate the positions of the movable portion 105 in the X direction and Y direction (X coordinate, Y coordinate), respectively.

The first servo controller 230_1 generates the control signal S4_1 so that the error between the feedback signal X _FB and the position command X _REF approaches zero. The first drive unit 220_1 generates a drive signal S2_1 according to the control signal S4_1. The control signal S4_1 is, for example, a current command, and the first drive unit 220_1 supplies the first actuator 106_1 with a drive current having an amount of current according to the control signal S4_1. The control signal S4_1 may be considered as a torque command.

Similarly, the second servo controller 230_2 receives the position detection signal S3_2 generated by the position detection element 110_2 as a feedback signal _YFB indicating the Y coordinate of the movable part 105. The second servo controller 230_2 generates the control signal S4_2 so that the error between the feedback signal Y _FB and the position command Y _REF approaches zero. The second drive unit 220_2 generates a drive signal S2_2 according to the control signal S4_2.

In FIG. 2, the configuration of the actuator driver 200 (220_1, 230_1, 240_1) 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.

FIG. 3 is a block diagram of the actuator driver 200 according to the embodiment. The 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. The driving unit 220 in FIG. 3 corresponds to the first driving unit 220_1 or the second driving unit 220_2 in FIG. 2. The position detection unit 240 in FIG. 3 corresponds to the first position detection unit 240_1 or the second position detection unit 240_2 in FIG. 2. Actuator 120 in FIG. 3 corresponds to actuator 106 in FIG. 2.

The actuator 120 is a voice coil motor, and includes a magnet 122 and a plurality of (three in this example) voice coils L1 to L3. Magnet 122 is attached to mover 124. The plurality of voice coils L1 to L3 are provided along the movable direction of the movable element 124.

The position detection section 240 generates a position detection signal (feedback signal) _PFB based on the output of the position detection element 110. 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. The position detection signal _PFB is fed back to the servo controller 230.

The servo controller 230 includes an error detector 232 and a compensator 234. The error detector 232 generates an error err between the position command P _REF and the feedback signal P _FB indicating the position of the movable part 105 . Error detector 232 can be configured with a subtracter.

The compensator 234 generates a control signal ctrl according to the error err. Compensator 234 is also referred to as a servo filter. The compensator 234 is, for example, a PI (proportional/integral) controller, and adds the value obtained by multiplying the error err by a proportional gain kp and the value obtained by multiplying the integral value of the error err by an integral gain ki, and generates a control signal. ctrl may be generated. Compensator 234 may be a PID (proportional-integral-derivative controller).

The drive section 220 includes a plurality of correction sections COMP1 to COMP3 and a plurality of drivers DR1 to DR3. The plurality of correction units COMP1 to COMP3 and the plurality of drivers DR1 to DR3 correspond to the plurality of voice coils L1 to L3.

A control signal ctrl is supplied to the plurality of correction units COMP1 to COMP3. Each correction unit COMPi (i=1, 2, 3) corrects the control signal ctrl according to the position detection signal _PFB indicating the position of the movable element. Correction characteristics differ for each voice coil. The corrected control signal ctrli is supplied to the corresponding driver DRi.

In this embodiment, the correction unit COMPi generates a correction gain gi according to the position detection signal _PFB . The correction unit COMPi then generates the control signal ctrli by multiplying the control signal ctrl by the correction gain gi.
ctrli=gi×ctrl

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

The above is the configuration of the actuator driver 200. Next, its operation will be explained.

First, the operation when the control signal ctrl is not corrected will be explained.

FIG. 4 is a diagram showing propulsive forces F1 to F3 generated by each of the plurality of voice coils L1 to L3. The propulsive force Fi is the propulsive force obtained when the control signal ctrl before correction is input to the driver DRi. The horizontal axis indicates the position P of the mover.

The propulsive force of each voice coil Li has a constant value within a certain range Ai, but when it deviates from that range Ai, it decreases and eventually reverses its direction. The range Ai is referred to as a stable output region. FIG. 3 shows a composite propulsive force F _SUM that is the sum of a plurality of propulsive forces F1 to F3. The synthetic propulsive force F _SUM has position dependence, and the followability and stability differ depending on the position, which is not preferable. As explained below, in the actuator driver 200 according to the embodiment, the control signal ctrl is corrected so that a constant propulsive force is obtained regardless of the position, that is, so that the unidependence of the composite propulsive force is reduced. be done.

FIG. 5 is a diagram illustrating correction of the propulsive force by the drive unit 220. The upper part of FIG. 5 shows the propulsive forces F1 to F3 without correction. In the middle part of FIG. 5, correction gains g1 to g3 are shown. The lower part of FIG. 5 shows the corrected propulsive forces F1' to F3' and their sum, the composite propulsive force F _SUM '=F1'+F2'+F3'.

In this example, the correction gain gi of the i-th correction unit COMPi is determined to take a constant value in a stable output area Ai where a constant propulsive force is obtained, and to be 0 outside the stable output area Ai. The propulsive force Fi' after correction is the propulsive force Fi before correction multiplied by the correction gain gi.

The combined propulsive force F _SUM , which is the sum of the corrected propulsive forces F1' to F3', remains substantially constant regardless of the position P. Note that here, in order to facilitate understanding and simplify the explanation, it is assumed that the composite propulsive force F _SUM is constant regardless of the position, but the present disclosure is not limited thereto. In reality, it is difficult to completely eliminate the positional dependence of the resultant propulsive force F _SUM , so compared to the resultant propulsive force F _SUM without the correction shown in Fig. 4, the resultant propulsive force F _SUM after correction is It is sufficient if the positional dependence of ' is small.

Those skilled in the art will understand that the position dependence of the propulsive 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 may be determined so that the position dependence of the corrected combined propulsive force F _SUM ′ becomes small.

FIG. 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 lookup table 224. The lookup table 224 of the correction unit COMPi stores the correspondence relationship between the position detection signal _PFB and the correction gain gi, and the correction gain gi corresponding to the current position detection signal _PFB is read out and the gain is supplied to circuit 222. The gain circuit 222 multiplies the control signal ctrl by a correction gain gi and outputs a corrected control signal ctrli.

The relationship between the position detection signal _PFB and the correction gain gi may be converted into a function, and the correction gain gi may be calculated by calculation.

The embodiments described above are merely examples, and those skilled in the art will understand that various modifications can be made to the combinations of their constituent elements and processing processes. Hereinafter, such modified examples will be explained.

(Modification 1)
In the embodiment, a closed-loop position control system has been described, but the present disclosure is not limited thereto, and the present disclosure is also applicable to an open-loop position control system.

FIG. 7 is a block diagram of an actuator driver 200A according to Modification 1. In the actuator driver 200A, a controller 230A is provided in place of the servo controller 230 in FIG. 3. The controller 230A supplies the position command _PREF to the drive unit 220 as a control signal ctrl.

Generally, in an open-loop position control system, the position detection element 110 is not necessary, but in this modification 1, the position detection element 110 is provided in order to determine the correction gains g1 to g3. According to this actuator driver 200A, the positional dependence of the combined propulsive force can be reduced.

(Modification 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 a lens shift, and the present disclosure also applies to an image stabilization mechanism using a prism. is applicable.

(Modification 3)
In the embodiment, a position control system for a camera shake correction mechanism has been described, but the present disclosure is not limited thereto, and can also be applied to a position control system for autofocus.

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

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

(Additional note)
Embodiments 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 an MM (Moving Magnet) type voice coil motor including a mover including a magnet and a plurality of voice coils arranged along a moving direction of the mover,
The actuator driver is
a drive unit that drives the plurality of voice coils according to a control signal;
Equipped with
The drive unit includes:
a plurality of correction units corresponding to the plurality of voice coils, each correcting the control signal according to a position detection signal indicating the position of the movable element;
a plurality of drivers corresponding to the plurality of voice coils, each of which drives a corresponding voice coil according to an output of a corresponding correction section;
Actuator driver.
(Item 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)
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 is
an error detector that generates an error between the target value and the position detection signal;
a proportional-integral controller subject to the error;
The actuator driver according to item 3, comprising:
(Item 5)
The actuator driver according to any one of items 1 to 4, which is monolithically integrated on one semiconductor substrate.
(Item 6)
image sensor and
a camera shake correction mechanism provided on the optical path of incidence to the image sensor;
an actuator that positions a movable part of the image stabilization mechanism;
The actuator driver according to any one of items 1 to 4,
A camera module.
(Item 7)
An electronic device comprising the camera module according to item 6.

L1, L2, L3 Voice coil 100 Camera module 102 Image sensor 104 Image stabilization lens 105 Movable part 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 unit 220 Drive unit 220_1 First drive unit 220_2 Second drive unit COMPi correction unit DRi driver 222 Gain circuit 224 Lookup table 230_1 First servo controller 230_ 2nd 2 servo controller 230 servo controller 232 error detector 234 compensator 240 position detection section 240_1 first position detection section 240_2 second position detection section

Claims

An actuator driver that drives an actuator that positions a movable part,
The actuator is an MM (Moving Magnet) type voice coil motor including a mover including a magnet and a plurality of voice coils arranged along a moving direction of the mover,
The actuator driver is
a drive unit that drives the plurality of voice coils according to a control signal;
Equipped with
The drive unit includes:
a plurality of correction units corresponding to the plurality of voice coils, each correcting the control signal according to a position detection signal indicating the position of the movable element;
a plurality of drivers corresponding to the plurality of voice coils, each of which drives a corresponding voice coil according to an output of a corresponding correction section;
Actuator driver.
The actuator driver according to claim 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.
The actuator driver according to claim 1 or 2, further comprising a servo controller that generates the control signal so that the position detection signal approaches a target value.
The servo controller is
an error detector that generates an error between the target value and the position detection signal;
a proportional-integral controller subject to the error;
The actuator driver according to claim 3, comprising:
The actuator driver according to claim 1 or 2, which is monolithically integrated on one semiconductor substrate.
image sensor and
a camera shake correction mechanism provided on the optical path of incidence to the image sensor;
an actuator that positions a movable part of the image stabilization mechanism;
The actuator driver according to claim 1 or 2,
A camera module.
An electronic device comprising the camera module according to claim 6.