Actuator for camera, camera module, and imaging device

Abstract

A high thrust actuator for a camera is provided without increasing the size of a magnet and a coil 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 so as to face 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

Technical Field

[0001] The present invention relates to an actuator for a camera, and more particularly, to an actuator for driving a camera module, an optical system or an imaging sensor for an autofocus function or an optical image stabilization function, and the camera module and an imaging device having the actuator. Background Art

[0002] In recent years, imaging sensors and lenses have become larger in many camera modules installed in portable devices such as smartphones and tablets or other cameras. As a result, the weight of the optical components driven for autofocus and optical image stabilization has continued to increase. Actuators require high power to drive weighted optical components.

[0003] Voice coil motor (VCM) is widely used as an actuator for autofocus and optical image stabilization. VCM is mainly composed of a magnet, a coil, and a yoke. It is a single-phase motor that is positioned by a magnetic field generated by the flow of direct current (DC). VCM is characterized by light weight and fast response speed. However, in order to make the VCM have high power, the size of the magnet or coil needs to be increased, which will cause the size of the camera module to increase. Therefore, there is a need for an actuator that can have higher output without increasing the size of the actuator. Summary of the invention

[0004] An object of the present invention is to provide a high thrust actuator for a camera without increasing the size of the magnets or coils used in the VCM.

[0005] According to a first aspect of the present invention, there is provided an actuator for a camera, the actuator comprising:

[0006] Fixed parts;

[0007] a movable member having an optical component;

[0008] a plurality of magnets supported on one of the fixed component and the movable component;

[0009] a coil supported on the other of the fixed part and the movable part so as to be opposed to the plurality of magnets,

[0010] The plurality of magnets are magnetized at a predetermined angle relative to a direction perpendicular to a surface facing the coil.

[0011] According to this aspect, the actuator can be miniaturized because a higher thrust than in a conventional actuator can be generated without increasing the size of the magnet or the coil. In addition, if the size of the magnet or the coil is the same as that of a conventional magnet or coil, the magnet or the coil can be driven even at a low current, thereby reducing the power consumption of the actuator.

[0012] According to a possible implementation of the first aspect, the plurality of magnets includes a pair of adjacent magnets having different polarities on surfaces facing the coil, and wherein the pair of adjacent magnets are magnetized at an angle so that the magnetization direction extends relative to a direction perpendicular to the surface facing the coil.

[0013] According to this implementation, the magnetic path in the direction from the magnet toward the coil can be larger than the conventional magnetization in the direction perpendicular to the surface opposite to the coil. Therefore, the component of the magnetic flux passing through the coil becomes larger.

[0014] According to a possible implementation manner of the first aspect, the plurality of magnets include a pair of adjacent magnets, and the pair of magnets have the same polarity of surfaces facing the coil.

[0015] According to this implementation, the spread of the magnetic field generated by adjacent pairs of magnets having the same polarity can be increased.

[0016] According to a possible implementation manner of the first aspect, the pair of adjacent magnets having the same polarity facing the surface of the coil are magnetized at a certain angle so that the magnetization direction becomes narrower relative to a direction perpendicular to the surface facing the coil.

[0017] According to this implementation, the spread of the magnetic field generated by adjacent pairs of magnets having the same polarity can be increased.

[0018] According to a possible implementation manner of the first aspect, a magnetic substance is provided on a surface of the plurality of magnets opposite to the surface facing the coil.

[0019] According to this implementation, the magnet can be firmly fixed to the support member. In addition, when two or more non-adjacent magnets having different polarities relative to the coil are inserted into the support member, the magnets are attracted by the magnetic substance, so that the magnets can be easily inserted.

[0020] According to a possible implementation manner of the first aspect, the optical component is an optical system, an imaging sensor, or a camera module.

[0021] According to a second aspect of the present invention, there is provided a camera module having the actuator for a camera as described above.

[0022] According to a third aspect of the present invention, there is provided an imaging device having the actuator for a camera as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments, the following briefly introduces the drawings required for these embodiments. Obviously, the drawings in the following description only depict some possible embodiments, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work, among which:

[0024] Figure 1 shows a basic configuration of a camera module to which an actuator according to an embodiment is applied;

[0025] Figure 2 shows an exploded perspective view of an actuator according to one embodiment;

[0026] Figure 3 shows a side cross-sectional view of an actuator according to one embodiment;

[0027] Figure 4A shows the arrangement of magnets in the fixed part of the actuator;

[0028] Figure 4B shows a cross-sectional view of an exemplary actuator;

[0029] Figure 4C shows a cross-sectional view of an exemplary actuator;

[0030] Figure 4D shows a cross-sectional view of an exemplary actuator;

[0031] Figure 5 A diagram showing magnetic field lines formed by a magnet of an actuator is shown, wherein (a) is a magnetic field line formed by a magnet of a conventional actuator using a VCM, and (b) is a magnetic field line formed by a magnet of an actuator according to an embodiment;

[0032] Figure 6 shows an exploded perspective view of an actuator according to one embodiment;

[0033] Figure 7 shows a side cross-sectional view of an actuator according to one embodiment;

[0034] Figure 8 shows the arrangement of magnets in the fixed part of the actuator;

[0035] Fig. 9 is a diagram illustrating magnetic lines of force formed by a magnet of an actuator according to one embodiment;

[0036] Fig.10 is a diagram illustrating a method of inserting a magnet into a fixing component of an actuator according to one embodiment. DETAILED DESCRIPTION

[0037] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the mode of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0038] Figure 1 : is a diagram showing a basic configuration of a camera module to which an actuator according to an embodiment of the present invention is applied. Although a module tilt OIS system that moves or rotates a camera module is described below, the present invention is also applicable to a lens shift system that moves a lens and a sensor shift system that moves an imaging sensor.

[0039] The camera module 100 is mounted on an imaging device, which includes a portable device such as a smartphone or a tablet computer or other cameras.

[0040] The camera module 100 is movably supported relative to the main body of the imaging device and can be independently moved in the X-axis direction (a direction perpendicular to the surface of the paper) and the Y-axis direction (a longitudinal direction of the paper).

[0041] 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 .

[0042] The lens 102 is provided on an incident light path of the image sensor 110 to guide subject light to the image sensor 110. The lens 102 is held by a lens holder 103. The lens holder 103 is arranged to be movable in the Z-axis direction (optical axis direction).

[0043] The image sensor 110 is composed of an imaging sensor that performs photoelectric conversion on the subject light to output a signal related to the captured image. For example, the image sensor 110 may be a complementary metal oxide semiconductor (CMOS) sensor. The AFE 112 converts the analog signal output from the image sensor 110 into a digital signal and outputs it to the control unit 106. The actuator 104 is a VCM actuator for moving the camera module 100 and the lens holder 103. As described above, the camera module 100 can be independently moved in the X-axis direction and the Y-axis direction, so the actuator 104 is used to independently move the camera module 100 in the X-axis direction and the Y-axis direction to achieve optical image stabilization. The actuator 104 is also used to move the lens 102 in the Z-axis direction to achieve autofocus.

[0044] The motion sensor 120 is used to detect the motion of the camera module 100. For example, the motion sensor 120 may be a gyro sensor. The motion sensor 120 outputs a motion signal indicating the detected motion of the camera module 100.

[0045] The position detector 108 is used to position the camera module 100. The position detection unit 108 may be a magnetic detection element such as a Hall sensor. In this case, the magnetic detection element outputs a position detection signal indicating the displacement of the camera module 100.

[0046] The control unit 106 has an actuator driver 114, an image processing circuit 116, and an encoder 118. The actuator driver 114 controls the actuator 104 to move the optical member. The optical member to be moved may include the camera module 100, the lens holder 103, the image sensor 110, and the like.

[0047] The actuator driver 114 sends a signal to the actuator 104 to implement optical image stabilization. The actuator driver 114 controls the movement of the camera module 100 based on the motion signal from the motion sensor 120. For example, when a gyro sensor is used as the motion sensor 120, the motion signal indicates the angular velocity in the yaw direction (X-axis direction) and the angular velocity in the pitch direction (Y-axis direction). The actuator driver 114 calculates the displacement of the angle by integrating the motion signals in the yaw direction and the pitch direction respectively. Then, the actuator driver 114 displaces the camera module 100 in response to the calculated angular displacement.

[0048] Furthermore, in autofocus, the actuator driver 114 may 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 direction (Z-axis direction) so as to maximize the contrast of the image output from the image processing circuit 116.

[0049] The image processing circuit 116 performs predetermined processing on the signal output by the AFE 112 to output an image signal in a digital format. The encoder converts the output image data in a digital format into the output image data in an analog format. The output image data is sent to the display 122. The display 122 displays an image based on the image signal received from the encoder 118, and may be, for example, a liquid crystal display (LCD).

[0050] In this embodiment, if Figure 1 As shown, the camera module 100 applies an optical image stabilization system, but the camera module 100 may be adaptively designed according to an object to be corrected. For example, if the camera module 100 applies a lens shift optical image stabilization system that moves the lens, the lens 102 is movably supported in the X direction and the Y direction. The position detector 108 detects the position of the lens 102, and the motion sensor 120 detects the movement of the lens 102. In addition, when the camera module 100 applies a sensor shift optical image stabilization system that moves the image sensor, the image sensor 110 is movably supported in the X direction and the Y direction. The position detection unit 108 detects the position of the image sensor 110, and the motion sensor 120 detects the movement of the image sensor 110.

[0051] (First embodiment)

[0052] Reference now Figure 2 and Figure 3 , wherein the configuration of the actuator 104 according to the first embodiment of the present invention will be described.

[0053] Figure 2 is an exploded perspective view of the actuator 104, Figure 3 2 is a side cross-sectional view of the actuator 104. The actuator 104 includes a fixed part 205, a magnetic substance 206, magnets 204a, 204b, a coil 203 and a movable part 202. The fixed part 205 is a supporting member that supports the magnets 204a, 204b. The fixed part 205 is made of a resin such as a super engineering plastic or a liquid crystal polymer, and is formed in a plate shape. The fixed part 205 has an opening 208 at a central position, and the magnets 204a, 204b are assembled in the opening. The movable part 202 is made of a resin such as a super engineering plastic or a liquid crystal polymer, and is formed in a plate shape. The coil 203 is fixed to the bottom of the movable part 202.

[0054] The magnetic substance 206 is embedded in the fixing member 205. The magnetic substance 206 is made of iron or the like, and is exposed at the opening 208.

[0055] In this embodiment, the component connected to the magnet is a fixed component, and the component connected to the coil is a movable component. On the contrary, the component connected to the magnet can be a movable component, and the component connected to the coil can be a fixed component.

[0056] Figure 4A 2 shows the arrangement of the magnets 204a, 204b in the fixed part 205. The adjacent magnets 204a, 204b having different polarities on the surfaces opposite to the coil 203 are magnetized at a certain angle so that the magnetization direction extends in the direction from the magnets 204a, 204b to the coil 203. Figure 4A As shown by the arrow in , the magnetization direction of magnet 204a is toward the upper left and is inclined at an angle θ relative to the direction perpendicular to the surface facing the coil 203. The magnetization direction of magnet 204b is toward the lower right and is inclined at an angle θ relative to the direction perpendicular to the surface facing the coil 203.

[0057] Preferably, the magnetization angle θ is magnetized at an angle of 10 to 40 degrees relative to the vertical direction of the opposite surface of the magnet facing the coil 203. In some embodiments, the angle θ of the magnetization direction of the magnets 204a, 204b may be different from each other.

[0058] Now combine FIG. 4B to FIG. 4D Some example implementations of actuators are described.

[0059] Figure 4B 2 is a cross-sectional view of an exemplary actuator for realizing an optical image stabilization function. The camera module 100 is fixed to the movable part 202 so that the direction from the magnets 204a, 204b toward the coil 203 is parallel to the optical axis direction of the lens 102. In some embodiments, the housing of the camera module 100 can be formed integrally with the movable part 202. The movable part 202 is retained in the main body of the imaging device so that it can move parallel to the surface of the coil 203. For example, the position detector 108 can 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.

[0060] The actuator driver 114 is a control part for moving the movable part 202 relative to the fixed part 205 by supplying power to the coil 203. The actuator driver 114 controls the current flowing to the coil 203 based on the motion signal from the motion sensor 120 and the position signal of the camera module 100 output from the position detector 108. When the current flows into the coil 203 and the coil 203 generates a magnetic field, the coil 203 applies a force between the magnets 204a and 204b placed opposite to each other. This force moves the movable part 202 in a plane parallel to the fixed part 205.

[0061] Figure 4C 2 is a cross-sectional view of an exemplary actuator for realizing an autofocus function. The lens holder 103 is fixed to the movable part 202 so that the direction from the magnets 204a, 204b to the coil 203 is perpendicular to the optical axis direction of the lens 102. In some embodiments, the lens holder 103 can be formed integrally with the movable part 202. When receiving an image signal output from the image processing circuit 116, the actuator driver 114 generates the movement amount of the lens 102 according to the contrast of the generated image. In addition, the actuator driver 114 controls the current flowing to the coil 203 based on the movement amount of the lens 102 and the position signal of the lens 102 output from the position detector 108.

[0062] Figure 4D 2 is a cross-sectional view of another exemplary actuator that realizes the optical image stabilization function. The image sensor 110 is fixed to the movable part 202 so that the direction from the magnets 204a, 204b to the coil 203 is perpendicular to the light receiving surface of the image sensor 110. The position detection unit 108 detects the position of the image sensor 110 and outputs it to the actuator driver 114. The actuator driver 114 controls the current flowing to the coil 203 based on the motion signal from the motion sensor 120 and the position signal of the image sensor 110 output from the position detector 108.

[0063] Reference now Figure 5 , wherein the operation of the actuator according to the present embodiment will be described. Figure 5 (a) in FIG. 5 shows magnetic field lines formed by magnets of a conventional actuator using VCM. Magnets 504a, 504b arranged opposite to coil 503 are magnetized perpendicular to the opposite surfaces. Magnetic field lines are indicated by arrows from the top surface of magnet 504a to magnet 504b via dotted line L3.

[0064] To achieve higher power using VCM, the magnet or coil needs to be enlarged, and the entire device becomes larger. It is also conceivable to increase the drive current without changing the size of the magnet or coil. However, in this case, the power consumption of the device will be high.

[0065] Figure 5 (b) in FIG. 1 shows the magnetic lines of force formed by the magnets of the actuator according to the present embodiment. The magnetization directions of the magnets 204a, 204b are oriented at a predetermined angle relative to the direction perpendicular to the surface of the magnets 204a, 204b facing the coil 203. Therefore, the magnetic field expands in the direction of the coil 203. This is Figure 5 (b) is shown by the magnetic field lines from magnet 204a to magnet 204b via dotted line L2. Figure 5 As shown in (b) in FIG. 1 , relative to the conventional vertical magnetization, the tilting in the magnetic direction increases the magnetic circuit in the direction toward the coil 203. Therefore, the vertical component of the magnetic flux passing through the coil 203 becomes larger. Accordingly, the Lorentz force generated by applying current to the coil 203 increases, and the actuator can obtain a high thrust. According to this embodiment, a higher thrust can be generated than in the conventional configuration, in which the magnet or coil is magnetized perpendicularly to the surface opposite to the coil without increasing the magnet or coil. Therefore, the actuator can be miniaturized. In addition, if the size of the magnet and the coil is 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.

[0066] (Second embodiment)

[0067] Reference now Figure 6 and Figure 7 , wherein the configuration of an actuator according to a second embodiment of the present invention will be described.

[0068] Figure 6 An exploded perspective view of the actuator 604 according to the present embodiment is shown. Figure 7 A side cross-sectional view of the actuator 604 is also shown. The actuator 604 may be used in Figure 1 The camera module 100 shown in . The actuator 604 includes a fixed part 605, magnets 614a, 614b, 614c and 614d, a coil 203 and a movable part 202. Non-adjacent magnets 614a, 614d having different polarities are slightly longer than adjacent magnets 614b, 614c having different polarities. Accordingly, the fixed part 605 is formed into a convex shape so that parts 609, 610 engage with the ends of the magnets 614a-614d. The fixed part 605 is made of resin and is formed into a plate shape. The fixed part 605 has an opening 608 at a central position, and the magnets 614a, 614b are assembled in the opening. The movable part 202 is made of resin and is formed into a plate shape. The coil 203 is fixed to the bottom of the movable part 202.

[0069] In this embodiment, the component connected to the magnet is a fixed component, and the component connected to the coil is a movable component. On the contrary, the component connected to the magnet can be a movable component, and the component connected to the coil can be a fixed component.

[0070] Figure 8 The arrangement of magnets 614a-614d in the fixed part 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 surface opposite to the coil 203. The pair of magnets 614a, 614b is magnetized at a certain angle so that the magnetization direction becomes narrower relative to the direction from the 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. In addition, adjacent magnets 614b, 614c with different polarities on the surface facing the coil 203 are magnetized at a certain angle so that the magnetization direction is expanded relative to the direction from the magnets 614b, 614c to the coil 203.

[0071] The magnetization direction of the magnet 614b is oriented toward the upper left, and is tilted at an angle θ relative to the direction perpendicular to the surface facing the coil 203. The magnetization direction of the magnet 614c is oriented toward the lower left, and is tilted at an angle θ relative to the direction perpendicular to the surface facing the coil 203. The magnetization direction of the magnet 614a is oriented toward the upper right, and is tilted at an angle θ relative to the direction perpendicular to the surface facing the coil 203. The magnetization direction of the magnet 614d is oriented toward the lower right, and the angle θ of the surface of the magnet 614d is tilted relative to the direction perpendicular to the surface facing the coil 203.

[0072] In some embodiments, the angle of the magnetization direction of at least one of the magnets 614a - 614d may be different from that of the other magnets.

[0073] refer to Fig. 9 , wherein the operation of the actuator according to the present embodiment will be described. Fig.10 An actuator according to the present embodiment is shown. The magnetization direction of the magnets 614a–614d is oriented at a predetermined angle relative to a direction perpendicular to the surface of the magnets 614a–614 facing the coil 203. The magnets 614a–614d have a pair of adjacent magnets 614a, 614b, which have the same polarity on the surface facing the coil 203, and the magnets 614a–614d also have a pair of magnets 614c, 614d, which have the same polarity on the surface facing the coil 203. Therefore, compared with the first embodiment, the magnetic field is further extended in the direction of the coil 203. This is Fig. 9614a, 614b via the dotted line L1 to the magnets 614c, 614d. According to this embodiment, a higher thrust than a conventional actuator can be generated without increasing the magnet or coil. Therefore, the actuator can be miniaturized. In addition, if the size of the magnet and coil is the same as before, these magnets and coils can be driven even at low current. Therefore, the power consumption of the actuator can be reduced.

[0074] like Figure 6 As shown, the fixing part 605 is provided with an opening 608, and the magnetic substance 206 is exposed in the opening 608. Therefore, when the magnets 614a-614d are inserted into the opening 608, the magnets 614a-614d are attracted in the direction of the arrow. Therefore, it can be easily inserted into the magnets 614a-614d. In addition, by attracting the magnets 614a-614d to the magnetic substance 206, the magnets 614a-614d are firmly fixed to the fixing part 605.

[0075] Reference now Fig.10 , wherein a method of inserting magnets 614a-614d into a fixed part 605 of an actuator 604 will be described. First, a pair of magnets 614a, 614d that are far apart are inserted into the fixed part 605 so that these magnets do not affect each other as much as possible. At this time, since the magnets 614a, 614d have different polarities on the surface opposite to the coil, the force acts on these magnets in the direction of mutual attraction. However, since the magnets 614a, 614d are attracted by the magnetic substance 206, they can be easily inserted into the fixed part 605.

[0076] The above embodiments can be applied to any camera unit that can use an optical image stabilization function or an autofocus function. For example, the above embodiments can be applied to a smartphone built-in camera, a tablet built-in camera, an action camera, an interchangeable lens camera, a surveillance camera, a car camera, an airplane camera, etc.

[0077] The above description is only a specific implementation of the present invention but is not intended to limit the protection scope of the present invention. Within the disclosed technical scope, any changes or substitutions that can be easily thought of by those skilled in the art should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. An actuator for a camera, characterized in that: include: Fixed parts; a movable member having an optical component; a plurality of magnets supported on one of the fixed component and the movable component; a coil supported on the other of the fixed part and the movable part so as to be opposed to the plurality of magnets, The plurality of magnets are magnetized at a predetermined angle relative to a direction perpendicular to a surface facing the coil.

2. The actuator for a camera according to claim 1, characterized in that: The plurality of magnets include a pair of adjacent magnets having different polarities of surfaces facing the coil, and wherein the pair of adjacent magnets are magnetized at an angle such that a 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 plurality of magnets have a pair of adjacent magnets, the pair of magnets having the same polarity of surfaces facing the coil.

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

5. The actuator for a camera according to claim 1, characterized in that: A magnetic substance is provided on surfaces of the plurality of magnets opposite to the surface facing the coil.

6. 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.

7. A camera module, characterized in that: There is an actuator for a camera according to any one of claims 1 to 5.

8. An imaging device, characterized in that: There is an actuator for a camera according to any one of claims 1 to 5.

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