Actuator for a camera, camera module and imaging device

Abstract

A high thrust actuator for a camera is provided without increasing the size of magnets and coils used in a VCM. An actuator for a camera includes a fixed member, a movable member having an optical member, a plurality of magnets supported on one of the fixed member and the movable member, and a coil supported on the other of the fixed member and the movable member to be opposed to the plurality of magnets. The plurality of magnets are magnetized at a predetermined angle with respect to a direction perpendicular to a surface facing the coil.

Description

[0001] This application is a divisional application. The original application has the application number 202380053302.2 and the original application date is September 15, 2023. The entire contents of the original application are incorporated herein by reference. Technical Field

[0002] The present invention relates to an actuator for a camera, and more specifically, to an actuator for driving a camera module, optical system or imaging sensor for autofocus or optical image stabilization, as well as the camera module and an imaging device having the actuator. Background Technology

[0003] In recent years, image sensors and lenses have become larger in many camera modules installed in portable devices such as smartphones and tablets, or in other cameras. Consequently, the weight of the optical components driven for autofocus and optical image stabilization has been increasing. Actuators require high power to drive the weighted optics.

[0004] Voice coil motors (VCMs) are widely used as actuators for autofocus and optical image stabilization. A VCM mainly consists of a magnet, a coil, and a yoke. It is a single-phase motor that uses a magnetic field generated by the flow of direct current (DC) for positioning. VCMs are characterized by their light weight and fast response. However, to achieve high power in a VCM, the size of the magnet or coil needs to be increased, which leads to an increase in the size of the camera module. Therefore, there is a need for an actuator that can provide higher output without increasing the actuator size. Summary of the Invention

[0005] The object of the present invention is to provide a high-thrust actuator for a camera without increasing the size of the magnet or coil used in a VCM.

[0006] According to a first aspect of the present invention, an actuator for a camera is provided, the actuator comprising:

[0007] Fixed components;

[0008] Movable parts, including optical components;

[0009] Multiple magnets are supported on one of the fixed component and the movable component;

[0010] A coil, supported on another of the fixed and movable components, is positioned opposite the plurality of magnets.

[0011] The plurality of magnets are magnetized at a predetermined angle relative to a direction perpendicular to the surface facing the coil.

[0012] Based on this aspect, the actuator can be miniaturized because a higher thrust than in conventional actuators can be generated without increasing the size of the magnet or the coil. Furthermore, if the dimensions of the magnet or the coil are the same as those of conventional magnets or coils, the magnet or the coil can be driven even at low currents, thereby reducing the power consumption of the actuator.

[0013] According to one possible implementation of the first aspect, the plurality of magnets includes a pair of adjacent magnets having different polarities on the surfaces facing the coil, and wherein the pair of adjacent magnets are magnetized at an angle such that the magnetization direction extends relative to a direction perpendicular to the surface facing the coil.

[0014] According to this implementation, the magnetic path along the direction from the magnet toward the coil can be larger compared to conventional magnetization along a direction perpendicular to the surface opposite the coil. Therefore, the component of the magnetic flux through the coil becomes larger.

[0015] According to one possible implementation of the first aspect, the plurality of magnets have a pair of adjacent magnets, the pair of magnets having the same polarity on the surfaces facing the coil.

[0016] According to this implementation method, the magnetic field generated by adjacent magnet pairs with the same polarity can be expanded.

[0017] According to one possible implementation of the first aspect, the pair of adjacent magnets having the same polarity on the surface facing the coil are magnetized at an angle such that the magnetization direction becomes narrower relative to the direction perpendicular to the surface facing the coil.

[0018] According to this implementation method, the magnetic field generated by adjacent magnet pairs with the same polarity can be expanded.

[0019] According to one possible implementation of the first aspect, a magnetic material is disposed on the surface of the plurality of magnets opposite to the surface facing the coil.

[0020] According to this implementation, the magnet can be securely fixed to the support member. Furthermore, when two or more non-adjacent magnets with different polarities opposite to the coil are inserted into the support member, the magnets are attracted by the magnetic material, making insertion easy.

[0021] According to one possible implementation of the first aspect, the optical component is an optical system, an imaging sensor, or a camera module.

[0022] According to a second aspect of the invention, a camera module is provided having an actuator for a camera as described above.

[0023] According to a third aspect of the invention, an imaging device is provided, the imaging device having an actuator for a camera as described above. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments, the accompanying drawings required for these embodiments are briefly described below. Obviously, the drawings described below only depict some possible embodiments, and those skilled in the art can obtain other drawings based on these drawings without creative effort, wherein:

[0025] Figure 1 The basic configuration of a camera module for an actuator according to one embodiment is shown;

[0026] Figure 2 An exploded perspective view of an actuator according to one embodiment is shown;

[0027] Figure 3 A side cross-sectional view of an actuator according to one embodiment is shown;

[0028] Figure 4A The arrangement of magnets in the stationary component of the actuator is shown;

[0029] Figure 4B A cross-sectional view of an exemplary actuator is shown;

[0030] Figure 4C A cross-sectional view of an exemplary actuator is shown;

[0031] Figure 4D A cross-sectional view of an exemplary actuator is shown;

[0032] Figure 5 A diagram showing magnetic field lines formed by the magnet of an actuator is shown, wherein (a) is the magnetic field line formed by the magnet of a conventional actuator using a VCM, and (b) is the magnetic field line formed by the magnet of an actuator according to one embodiment;

[0033] Figure 6 An exploded perspective view of an actuator according to one embodiment is shown;

[0034] Figure 7 A side cross-sectional view of an actuator according to one embodiment is shown;

[0035] Figure 8 The arrangement of magnets in the stationary component of the actuator is shown;

[0036] Figure 9 This is a diagram showing magnetic field lines formed by the magnet of an actuator according to one embodiment;

[0037] Figure 10 This is a diagram illustrating a method of inserting a magnet into a fixed part of an actuator according to one embodiment. Detailed Implementation

[0038] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.

[0039] Figure 1 This is a diagram illustrating a basic configuration of a camera module using an actuator according to an embodiment of the present invention. While a module tilt OIS system for moving or rotating a camera module is described below, the invention is also applicable to lens displacement systems for moving lenses and sensor displacement systems for moving imaging sensors.

[0040] The camera module 100 is mounted on an imaging device, which includes portable devices such as smartphones or tablets or other cameras.

[0041] The camera module 100 is movably supported relative to the main body of the imaging device. The camera module 100 can move independently along the X-axis (perpendicular to the paper surface) and the Y-axis (the longitudinal direction of the drawing).

[0042] The camera module 100 includes a lens 102, an image sensor 110, an actuator 104, a control unit 106, a position detector 108, an analog front end (AFE) 112, and a motion sensor 120.

[0043] Lens 102 is positioned in the incident light path of image sensor 110 to guide the subject light to image sensor 110. Lens 102 is held by lens holder 103. Lens holder 103 is movably configured along the Z-axis direction (optical axis direction).

[0044] Image sensor 110 comprises an imaging sensor that performs photoelectric conversion on the subject light to output a signal related to the captured image. For example, image sensor 110 may be a complementary metal-oxide-semiconductor (CMOS) sensor. AFE 112 converts the analog signal output from image sensor 110 into a digital signal and outputs it to control unit 106. Actuator 104 is a VCM actuator used to move camera module 100 and lens mount 103. As described above, camera module 100 can move independently along the X-axis and Y-axis, therefore actuator 104 is used to move camera module 100 independently along the X-axis and Y-axis to achieve optical image stabilization. Actuator 104 is also used to move lens 102 along the Z-axis to achieve autofocus.

[0045] Motion sensor 120 is used to detect the motion of camera module 100. For example, motion sensor 120 may be a gyroscope sensor. Motion sensor 120 outputs a motion signal that indicates the detected motion of camera module 100.

[0046] The position detector 108 is used to position the camera module 100. The position detection unit 108 may employ a magnetic detection element such as a Hall sensor. In this case, the magnetic detection element outputs a position detection signal that indicates the displacement of the camera module 100.

[0047] The control unit 106 includes an actuator driver 114, an image processing circuit 116, and an encoder 118. The actuator driver 114 controls the actuator 104 to move optical components. The optical components to be moved may include a camera module 100, a lens holder 103, an image sensor 110, etc.

[0048] Actuator driver 114 sends signals to actuator 104 to achieve optical image stabilization. Actuator driver 114 controls the movement of camera module 100 based on motion signals from motion sensor 120. For example, when a gyroscope sensor is used as motion sensor 120, the motion signals indicate the angular velocity in the yaw direction (X-axis direction) and the angular velocity in the pitch direction (Y-axis direction). Actuator driver 114 calculates the angular displacement by integrating the motion signals in the yaw and pitch directions, respectively. Then, actuator driver 114 displaces camera module 100 in response to the calculated angular displacement.

[0049] Furthermore, in autofocus, the actuator driver 114 can control the movement of the lens 102 in response to the contrast of the image output from the image processing circuit 116. For example, the actuator driver 114 controls the actuator 104 to move the lens 102 along the optical axis (Z-axis direction) to maximize the contrast of the image output from the image processing circuit 116.

[0050] Image processing circuit 116 performs predetermined processing on the signal output from AFE 112 to output a digital image signal. Encoder converts the digital output image data into analog output image data. The output image data is sent to display 122. Display 122 displays an image based on the image signal received from encoder 118, and may be, for example, a liquid crystal display (LCD).

[0051] In this embodiment, as Figure 1 As shown, camera module 100 employs an optical image stabilization system, but camera module 100 can be adaptively designed according to the object to be corrected. For example, if camera module 100 employs a lens-shift optical image stabilization system that moves the lens, then lens 102 is movably supported along the X and Y directions. Position detector 108 detects the position of lens 102, and motion sensor 120 detects the movement of lens 102. Furthermore, when camera module 100 employs a sensor-shift optical image stabilization system that moves the image sensor, image sensor 110 is movably supported along the X and Y directions. Position detection unit 108 detects the position of image sensor 110, and motion sensor 120 detects the movement of image sensor 110.

[0052] (First Embodiment)

[0053] Now for reference Figure 2 and Figure 3 The configuration of the actuator 104 according to a first embodiment of the present invention will be described therein.

[0054] Figure 2 This is an exploded perspective view of actuator 104. Figure 3 This is a side cross-sectional view of actuator 104. Actuator 104 includes a fixed component 205, a magnetic material 206, magnets 204a and 204b, a coil 203, and a movable component 202. The fixed component 205 is a support member that supports the magnets 204a and 204b. The fixed component 205 is made of resin such as super engineering plastic or liquid crystal polymer and is formed in a plate shape. The fixed component 205 has an opening 208 at its center, in which the magnets 204a and 204b are assembled. The movable component 202 is made of resin such as super engineering plastic or liquid crystal polymer and is formed in a plate shape. The coil 203 is fixed to the bottom of the movable component 202.

[0055] Magnetic material 206 is embedded in fixing component 205. Magnetic material 206 is made of iron or the like and is exposed at opening 208.

[0056] In this embodiment, the component connected to the magnet is a fixed component, and the component connected to the coil is a movable component. Conversely, the component connected to the magnet can be a movable component, and the component connected to the coil can be a fixed component.

[0057] Figure 4A The arrangement of magnets 204a and 204b in the fixing component 205 is shown. Adjacent magnets 204a and 204b, with surfaces opposite to the coil 203 and possessing different polarities, are magnetized at a certain angle, such that the magnetization direction extends from the magnets 204a and 204b towards the coil 203. Figure 4A As indicated by the arrows, magnet 204a is magnetized towards the upper left and tilted at an angle θ relative to the direction perpendicular to the surface facing coil 203. Magnet 204b is magnetized towards the lower right and tilted at an angle θ relative to the direction perpendicular to the surface facing coil 203.

[0058] Preferably, the magnetization angle θ is magnetized at an angle of 10 to 40 degrees relative to the perpendicular direction of the opposing surface of the magnet facing the coil 203. In some embodiments, the magnetization angle θ of the magnets 204a and 204b may be different from each other.

[0059] Now we will combine Figures 4B to 4D Describe some exemplary implementations of the actuator.

[0060] Figure 4B This is a cross-sectional view of an exemplary actuator for implementing optical image stabilization. The camera module 100 is fixed to the movable component 202 such that the direction from the magnets 204a, 204b toward the coil 203 is parallel to the optical axis of the lens 102. In some embodiments, the housing of the camera module 100 may be integrally formed with the movable component 202. The movable component 202 is held within the body of the imaging device such that it can move parallel to the surface of the coil 203. For example, a position detector 108 may be disposed inside the coil 203. The position detection unit 108 detects the position of the camera module 100 and outputs it to the actuator driver 114.

[0061] Actuator driver 114 is a control unit used to move movable member 202 relative to fixed member 205 by supplying power to coil 203. Actuator driver 114 controls the current flowing to coil 203 based on motion signals from motion sensor 120 and position signals from camera module 100 output from position detector 108. When current flows into coil 203 and coil 203 generates a magnetic field, coil 203 applies a force between opposing magnets 204a, 204b. This force causes movable member 202 to move in a plane parallel to fixed member 205.

[0062] Figure 4C This is a cross-sectional view of an exemplary actuator for implementing autofocus. The lens holder 103 is fixed to the movable component 202 such that the direction from the magnets 204a, 204b to the coil 203 is perpendicular to the optical axis of the lens 102. In some embodiments, the lens holder 103 may be integrally formed with the movable component 202. When an image signal is received from the image processing circuit 116, the actuator driver 114 generates the amount of movement of the lens 102 based on the contrast of the generated image. Furthermore, the actuator driver 114 controls the current flowing to the coil 203 based on the amount of movement of the lens 102 and the position signal of the lens 102 output from the position detector 108.

[0063] Figure 4D This is a cross-sectional view of another exemplary actuator for implementing optical image stabilization. Image sensor 110 is fixed to movable component 202 such that the direction from magnets 204a, 204b to coil 203 is perpendicular to the light-receiving surface of image sensor 110. Position detection unit 108 detects the position of image sensor 110 and outputs it to actuator driver 114. Actuator driver 114 controls the current flowing to coil 203 based on motion signals from motion sensor 120 and position signals of image sensor 110 output from position detector 108.

[0064] Now for reference Figure 5 The operation of the actuator according to this embodiment will be described therein. Figure 5 (a) shows the magnetic field lines formed by magnets using a conventional actuator employing a VCM. Magnets 504a and 504b, arranged opposite to coil 503, are magnetized perpendicularly to their opposing surfaces. The magnetic field lines are indicated by arrows from the top surface of magnet 504a through dashed line L3 to magnet 504b.

[0065] To achieve higher power using a VCM, the magnet or coil needs to be enlarged, making the entire device larger. It's also conceivable to increase the drive current without changing the magnet or coil size. However, in this case, the device's power consumption would be very high.

[0066] Figure 5 (b) shows the magnetic field lines formed by the magnets of the actuator according to this embodiment. The magnetization directions of the magnets 204a and 204b are oriented at a predetermined angle relative to the direction perpendicular to the surface of the magnets 204a and 204b facing the coil 203. Therefore, the magnetic field extends along the direction of the coil 203. This is in Figure 5 In (b) of the diagram, the magnetic field lines from magnet 204a to magnet 204b are shown via the dashed line L2. Figure 5 As shown in (b), tilting along the magnetic direction increases the magnetic path in the direction toward coil 203, compared to conventional perpendicular magnetization. Therefore, the vertical component of the magnetic flux through coil 203 becomes larger. Correspondingly, the Lorentz force generated by applying current to coil 203 increases, and the actuator can achieve high thrust. According to this embodiment, higher thrust can be generated than in conventional configurations where the magnet or coil is magnetized perpendicular to the surface opposite the coil without increasing the size of the magnet or coil. Therefore, the actuator can be miniaturized. Furthermore, if the dimensions of the magnet and coil remain the same as before, these magnets and coils can be driven even at low currents. Therefore, the power consumption of the actuator can be reduced.

[0067] (Second Embodiment)

[0068] Now for reference Figure 6 and Figure 7 The configuration of the actuator according to the second embodiment of the present invention will be described therein.

[0069] Figure 6 An exploded perspective view of the actuator 604 according to this embodiment is shown. Figure 7 A side cross-sectional view of actuator 604 is also shown. Actuator 604 can be applied to... Figure 1 The camera module 100 is shown. The actuator 604 includes a fixed member 605, magnets 614a, 614b, 614c, and 614d, a coil 203, and a movable member 202. Non-adjacent magnets 614a and 614d, having different polarities, are slightly longer than adjacent magnets 614b and 614c, which also have different polarities. Accordingly, the fixed member 605 is convex, such that members 609 and 610 engage with the ends of magnets 614a–614d. The fixed member 605 is made of resin and is plate-shaped. The fixed member 605 has an opening 608 at its center, in which magnets 614a and 614b are fitted. The movable member 202 is made of resin and is plate-shaped. The coil 203 is fixed to the bottom of the movable member 202.

[0070] In this embodiment, the component connected to the magnet is a fixed component, and the component connected to the coil is a movable component. Conversely, the component connected to the magnet can be a movable component, and the component connected to the coil can be a fixed component.

[0071] Figure 8 The arrangement of magnets 614a–614d in the fixing component 605 is shown. Magnets 614a–614d have a pair of adjacent magnets 614a, 614b and a pair of magnets 614c, 614d, which have the same polarity on the surfaces opposite to the coil 203. The pair of magnets 614a, 614b are magnetized at an angle such that the magnetization direction becomes narrower relative to the direction from magnets 614a, 614b to the coil 203. The magnetization direction of the pair of magnets 614c, 614d is similar to that of the pair of magnets 614a, 614b. Furthermore, adjacent magnets 614b, 614c, with different polarities on the surface facing the coil 203 are magnetized at an angle such that the magnetization direction expands relative to the direction from magnets 614b, 614c to the coil 203.

[0072] Magnet 614b is magnetized towards the upper left and tilted at an angle θ relative to the direction perpendicular to the surface facing coil 203. Magnet 614c is magnetized towards the lower left and tilted at an angle θ relative to the direction perpendicular to the surface facing coil 203. Magnet 614a is magnetized towards the upper right and tilted at an angle θ relative to the direction perpendicular to the surface facing coil 203. Magnet 614d is magnetized towards the lower right, and the angle θ of the surface of magnet 614d is tilted relative to the direction perpendicular to the surface facing coil 203.

[0073] In some embodiments, the magnetization direction angle of at least one of the magnets 614a–614d may be different from that of the other magnets.

[0074] refer to Figure 9 The operation of the actuator according to this embodiment will be described therein. Figure 10 An actuator according to this embodiment is shown. The magnetization direction of magnets 614a–614d is oriented at a predetermined angle relative to the direction perpendicular to the surface of magnets 614a–614d facing coil 203. Magnets 614a–614d have a pair of adjacent magnets 614a, 614b, which have the same polarity on the surface facing coil 203, and magnets 614a–614d also have a pair of magnets 614c, 614d, which have the same polarity on the surface facing coil 203. Therefore, compared to the first embodiment, the magnetic field extends further along the direction of coil 203. This is in Figure 9The magnetic field lines from magnets 614a and 614b to magnets 614c and 614d via dashed line L1 are shown in the diagram. According to this embodiment, a higher thrust than conventional actuators can be generated without increasing the size of the magnets or coils. Therefore, the actuator can be miniaturized. Furthermore, if the dimensions of the magnets and coils remain the same as before, these magnets and coils can be driven even at low currents. Therefore, the power consumption of the actuator can be reduced.

[0075] like Figure 6 As shown, the fixing member 605 is provided with an opening 608, through which the magnetic material 206 is exposed. Therefore, when magnets 614a–614d are inserted into the opening 608, they are attracted in the direction of the arrow. Thus, it is easy to insert magnets 614a–614d into the fixing member 605. Furthermore, by attracting magnets 614a–614d to the magnetic material 206, magnets 614a–614d are securely fixed to the fixing member 605.

[0076] Now for reference Figure 10 The method of inserting magnets 614a–614d into the fixing member 605 of actuator 604 will be described. First, a pair of magnets 614a and 614d, spaced far apart, are inserted into the fixing member 605 such that these magnets do not interfere with each other as much as possible. At this time, since magnets 614a and 614d have different polarities on their surfaces opposite the coil, a force acts on these magnets in the direction of mutual attraction. However, since magnets 614a and 614d are attracted by the magnetic material 206, they can be easily inserted into the fixing member 605.

[0077] The above embodiments can be applied to any camera unit that can use optical image stabilization or autofocus. For example, the above embodiments can be applied to built-in cameras of smartphones, built-in cameras of tablets, action cameras, interchangeable lens cameras, surveillance cameras, vehicle-mounted cameras, aircraft-mounted cameras, etc.

[0078] The above description is merely a specific implementation of the present invention and is not intended to limit the scope of protection of the present invention. Any variations or substitutions that are readily conceived by those skilled in the art within the scope of the disclosed technology should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An actuator for a camera, characterized in that, include: The fixed component has an opening; A movable component, the movable component including optical components; coil; Multiple magnets are disposed within the opening. The multiple magnets have a pair of adjacent magnets. The pair of magnets have the same polarity on the surface facing the coil. The pair of magnets have different lengths, namely a long magnet and a short magnet. The opening includes two adjacent spaces in the arrangement direction of the pair of magnets. The pair of magnets are respectively disposed in the two spaces. The length of the space for accommodating the long magnet is greater than the length of the space for accommodating the short magnet. The space for accommodating the long magnet is used to restrict the position of the long magnet in both the length direction and the arrangement direction. The space for accommodating the short magnet is used to restrict the position of the short magnet in the length direction. A magnetic material is embedded in the fixing component and exposed at the opening; The plurality of magnets are connected to the fixed component, and the coil is connected to the movable component to be opposite to the plurality of magnets. The magnetization direction of the plurality of magnets is at a predetermined angle to the direction perpendicular to the surface of the coil.

2. The actuator for a camera according to claim 1, characterized in that, The plurality of magnets includes a pair of adjacent magnets having different polarities on the surfaces facing the coil, and wherein the pair of adjacent magnets are magnetized at an angle such that the magnetization direction extends relative to a direction perpendicular to the surface facing the coil.

3. The actuator for a camera according to claim 1, characterized in that, The pair of adjacent magnets having the same polarity on the surface facing the coil are magnetized at an angle such that the magnetization direction becomes narrower relative to the direction perpendicular to the surface facing the coil.

4. The actuator for a camera according to claim 1, characterized in that, A magnetic material is disposed on the surface of the plurality of magnets opposite to the surface facing the coil.

5. The actuator for a camera according to claim 1, characterized in that, The optical component is an optical system, an imaging sensor, or a camera module.

6. A camera module, characterized in that, It has an actuator for a camera according to any one of claims 1 to 4.

7. An imaging device, characterized in that, It has an actuator for a camera according to any one of claims 1 to 4.

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