WO2022052083A1 - Long stroke optical image stabilization system and method - Google Patents

Long stroke optical image stabilization system and method Download PDF

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Publication number
WO2022052083A1
WO2022052083A1 PCT/CN2020/114969 CN2020114969W WO2022052083A1 WO 2022052083 A1 WO2022052083 A1 WO 2022052083A1 CN 2020114969 W CN2020114969 W CN 2020114969W WO 2022052083 A1 WO2022052083 A1 WO 2022052083A1
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WO
WIPO (PCT)
Prior art keywords
base
optical image
image stabilization
lens holder
wire
Prior art date
Application number
PCT/CN2020/114969
Other languages
French (fr)
Inventor
Atsuta KAZUYA
Sekiguchi NAOKI
Original Assignee
Huawei Technologies Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Huawei Technologies Co., Ltd. filed Critical Huawei Technologies Co., Ltd.
Priority to CN202080105026.6A priority Critical patent/CN116113875A/en
Priority to PCT/CN2020/114969 priority patent/WO2022052083A1/en
Publication of WO2022052083A1 publication Critical patent/WO2022052083A1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/64—Imaging systems using optical elements for stabilisation of the lateral and angular position of the image
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B30/00—Camera modules comprising integrated lens units and imaging units, specially adapted for being embedded in other devices, e.g. mobile phones or vehicles
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B5/00—Adjustment of optical system relative to image or object surface other than for focusing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/60—Control of cameras or camera modules
    • H04N23/68—Control of cameras or camera modules for stable pick-up of the scene, e.g. compensating for camera body vibrations
    • H04N23/682—Vibration or motion blur correction
    • H04N23/685—Vibration or motion blur correction performed by mechanical compensation
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B2205/00—Adjustment of optical system relative to image or object surface other than for focusing
    • G03B2205/0007—Movement of one or more optical elements for control of motion blur
    • G03B2205/0038—Movement of one or more optical elements for control of motion blur by displacing the image plane with respect to the optical axis
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B2205/00—Adjustment of optical system relative to image or object surface other than for focusing
    • G03B2205/0053—Driving means for the movement of one or more optical element
    • G03B2205/0076—Driving means for the movement of one or more optical element using shape memory alloys

Definitions

  • the present invention relates to a long stroke optical image stabilization system and method. Especially, the present invention relates to a long stroke optical image stabilization system and method to be used in a camera module or a camera unit of various products, in particular, various mobile electronic devices including smartphones, mobile phones, etc. The present invention also relates to a product including such an optical image stabilization system.
  • the camera module contains an optical image stabilization (hereinafter, referred to as "OIS" ) system, as is well known to those skilled in the art.
  • OIS optical image stabilization
  • the OIS system is intended to enhance a photo capability, and this capability becomes one of the major functionalities in a smartphone or a mobile phone, etc.
  • the OIS system may also increase the lens weight. This is because a wider imaging area needs to be provided in order to realize the functionality as stated above.
  • a lens actuator installed in the camera module needs to move such a heavy lens in order to realize the functionality of the OIS system.
  • the size of the actuator is constrained due to the limited installation space inside a smartphone or a mobile phone.
  • the VCM is mainly composed of a coil and a magnet.
  • the VCM is a drive unit that obtains a thrust force by passing an electric current through the coil.
  • SMA shape memory alloy
  • a wire manufactured from SMA has a characteristic of deforming, for example expanding or contracting, when its temperature is raised by the application of electric current, as is well known to those skilled in the art. This characteristic of the SMA wire is used to drive the lens.
  • the OIS system of the VCM type is major solution in the camera module of a smartphone or a mobile phone, it is necessary to increase the size of the coil and the magnet which consists the VCM in order to correspond a heavy weight of the lens.
  • the OIS system of the VCM type a further expansion of the coil and the magnet is necessary to achieve longer stroke of the optical lens.
  • the OIS system of the VCM type has a problem in relation to a magnetic interference.
  • the OIS system of the SMA wire type produces a large thrust force, and thus can easily drive a heavy lens.
  • the OIS system of the SMA wire type contrary to the OIS system of the VCM type, the OIS system of the SMA wire type has no problem in relation to magnetic interference.
  • existing SMA wire type systems are not suitable for a long stroke operation of the optical lens.
  • JP2018018083A discloses a lens driver that is configured to move a lens using a shape memory alloy (SMA) wire.
  • This device includes: a first drive mechanism for moving a lens holder along an optical axis of the lens; and a second drive mechanism including a SMA wire assembly electrically connected to a circuit board.
  • JP2015518977A also discloses a lens driver that uses a SMA wire for realizing an optical image stabilization (OIS) effect.
  • OIS optical image stabilization
  • an object of the present invention is to provide a novel optical image stabilization system and method which can overcome or at least alleviate the problems stated above in relation to the prior art devices.
  • a more specific object of the present invention is to provide a novel optical image stabilization system and method that can realize a longer stroke of the optical lens than prior art devices within a limited small space without magnetic interference.
  • an optical image stabilization system comprising: a base having a support surface; a lens holder that holds at least one optical lens for acquiring an optical image, wherein the lens holder is provided on the base such that it can move relative to the base in a direction parallel to the support surface of the base; at least one actuator for moving the lens holder relative to the base, wherein the actuator comprises a shape memory alloy wire whose length changes by being energized, wherein the optical image stabilization system further comprises at least one wire turning element, and wherein the shape memory alloy wire is arranged so as to be turned at least once using the wire turning element.
  • the present invention also provides an optical image stabilization method to be implemented in the system as stated above, the method comprising a step of: operating the at least one actuator for moving the lens holder relative to the base in a direction needed for an image stabilization, by energizing the shape memory alloy wire of the at least one actuator.
  • the present invention further provides a product including a camera module, wherein the camera module comprises the optical image stabilization system as stated above.
  • the shape memory alloy wire forming the actuator is connected to the lens holder via at least one wire turning element and can drive the lens holder in a desired direction. Therefore, according to the present invention, the total length of the shape memory alloy wire can be made longer according to the number of times of turning, as compared with the conventional actuator that does not have such a configuration. This increases the total amount of deformation of the shape memory alloy wire (i.e., a stroke of the actuator) , and as a result, an amount of movement of the lens holder connected to the shape memory alloy wire can be significantly increased as compared with a conventional actuator.
  • optical image stabilization system is particularly suitable for being incorporated into products, for example the latest mobile electronic devices, that have a camera module that requires the movement of large, heavy lenses with long strokes within a limited small space.
  • turning means changing the direction of the shape memory alloy wire at a certain point.
  • the angle between a wire section before the direction thereof is changed and a wire section after the direction thereof is changed may be 45° to 135°, preferably 60° to 120°, particularly preferably 80° to 100°, for example 85° to 95°.
  • the at least one wire turning element may comprise: two base-side wire turning elements provided on the base; and a holder-side wire turning element provided on the lens holder, wherein the holder-side wire turning element is arranged between the two base-side wire turning elements along an extension direction of the shape memory alloy wire.
  • the shape memory alloy wire extends around the lens holder in a substantially looped fashion through the two base-side wire turning elements and the holder-side wire turning element.
  • the two base-side wire turning elements and the holder-side wire turning element may be arranged such that a first virtual line connecting the two base-side wire turning elements with each other and a second virtual line connecting the holder-side wire turning element and a midpoint of the first virtual line, are orthogonal to each other. That is, in this preferred aspect, the two base-side wire turning elements are arranged symmetrically with the second virtual line in between. This aspect provides a particularly good balance of driving forces of the actuator.
  • the base-side wire turning element may be a pulley rotatably provided on the base.
  • the holder-side wire turning element may be a pulley rotatably provided on the lens holder.
  • the base-side wire turning element and/or the holder-side wire turning element may be a boss having, for example, a circular cross section. In this case, the outer peripheral surface of the boss is preferably subjected to a friction reduction treatment (using for example) .
  • two ends of the shape memory alloy wire may be fixed to a stud protruding from the support surface of the base.
  • the stud is shared by two ends of the shape memory alloy wire.
  • the shape memory alloy wire may be energized through the shared stud.
  • the electrical wiring architecture for supplying power to the shape memory alloy wire can be particularly simplified.
  • the stud may be provided at a corner of the base.
  • the stud is preferably arranged on the extension of the second virtual line connecting the holder-side wire turning element and the midpoint of the first virtual line.
  • the optical image stabilization system may comprise a plurality of, in particular, four actuators operable independently of each other. In this case, adjacent ones of the four actuators are arranged approximately 90 degrees apart from each other.
  • this aspect is particularly preferred. This is because by adopting this configuration, the lens holder can be freely moved with respect to the base (for example, upward or downward, left or right, and a combination thereof) .
  • the required number i.e., four
  • each pulley may have an annular groove on its peripheral surface for receiving an associated wire. In this case, the height positions of the annular groove of each pulley from the support surface of the base may be different from each other so that mutual interference between different wires is prevented.
  • the lens holder may include: an auto focusing part operatively associated with the at least one optical lens; and a movable frame which fixedly receives the auto focusing part.
  • the holder-side wire turning element (s) may be arranged on the movable frame.
  • the optical image stabilization system may further comprises a leaf spring interposed between the base and the lens holder.
  • the lens holder is supported and urged to a central position thereof by the leaf spring.
  • the spring shape is not particularly limited, but, for example, an S-shaped one having a circular opening for exposing the lens in the center thereof can be used.
  • the system to be used to implement this method may comprise four actuators arranged approximately 90 degrees apart from each other.
  • two or three actuators of the four actuators are operated simultaneously.
  • the lens holder can be freely moved with respect to the base (for example, upward or downward, left or right, and a combination thereof) .
  • the product may be a device, an apparatus, an equipment, a machine, a facility, a tool, or the like, which includes the camera module.
  • the product may be a mobile electronic device including the camera module.
  • FIG. 1 is a schematic view of a product, i.e., a smartphone that incorporates an optical image stabilization (OIS) system according to one embodiment of the present invention.
  • OIS optical image stabilization
  • FIG. 2 is a plane view of the OIS system shown in FIG. 1.
  • FIG. 3 is a perspective view of the OIS system shown in FIG. 1 in the disassembled state.
  • FIG. 4 is a perspective view of the corner area of the OIS system shown in FIG. 1.
  • FIG. 5 is a plane view of the OIS system shown in FIG. 1, showing the positional relationship of various pulleys that guide a shape memory alloy (SMA) wire, wherein the SMA wires are shown in phantom line.
  • SMA shape memory alloy
  • FIG. 6 is a plane view of the OIS system shown in FIG. 1, indicating eight movement directions of the lens holder, wherein a leaf spring is omitted for clarity.
  • FIG. 7 is a table showing the relationship between the degree of energizing (heating) of each SMA wire and a moving direction of the lens holder.
  • FIG. 8 is a plane view of the OIS system shown in FIG. 1, showing a state in which the lens holder has been moved upward by the operation of some related actuators.
  • FIG. 9 is a plane view of the OIS system shown in FIG. 1, showing a state in which the lens holder has been moved to the downward by the operation of some related actuators.
  • FIG. 10 is a plane view of the OIS system shown in FIG. 1, showing a state in which the lens holder has been moved to the right side by the operation of some related actuators.
  • FIG. 11 is a plane view of the OIS system shown in FIG. 1, showing a state in which the lens holder has been moved to the left side by the operation of some related actuators.
  • FIG. 12 is a plane view of the OIS system shown in FIG. 1, showing a state in which the lens holder has been moved upper right by the operation of some related actuators.
  • FIG. 13 is a plane view of the OIS system shown in FIG. 1, showing a state in which the lens holder has been moved lower right by the operation of some related actuators.
  • FIG. 14 is a plane view of the OIS system shown in FIG. 1, showing a state in which the lens holder has been moved upper left by the operation of some related actuators.
  • FIG. 15 is a plane view of the OIS system shown in FIG. 1, showing a state in which the lens holder has been moved lower left by the operation of some related actuators.
  • the following exemplary embodiments of the present invention relate to an optical image stabilization system and method to be used in a camera module, but not limited thereto, of the products like a mobile electronic device, in particular a smartphones. Furthermore, the following exemplary embodiments of the present invention also relate to such products, in particular a mobile electronic device, including a camera module which comprises the optical image stabilization system being one exemplary embodiment of the present invention.
  • the product can be any device, any apparatus, any equipment, any machine, any facility, any tool, or the like, which includes a camera module.
  • FIG. 1 shows a mobile electronic device 1, that is, a smartphones according to one preferred embodiment of the present invention.
  • the mobile electronic device 1 includes a camera module 1a which is built into it.
  • the camera module 1a comprises an optical image stabilization system (hereinafter, referred to as "OIS system” ) 10 as detailed below.
  • OIS system optical image stabilization system
  • FIG. 2 shows a plane view of the OIS system 10.
  • the OIS system 10 mainly comprises: a base 100; a lens holder 200; and a plurality of, in particular, four, i.e., first to fourth actuators 410, 420, 430, 440 operable independently of each other.
  • the base 100 has a support surface 110.
  • the base 100 has a circular opening 120 for exposing a lens (described below) received in the lens holder 200.
  • a plurality of plate-shaped stoppers 130a to 130h project so as to surround the circular opening 120.
  • the stoppers 130a to 130h cooperatively define a substantially square movable area of the lens holder 200.
  • the lens holder 200 holds at least one, in this embodiment, two, three, or four optical lenses 300 for acquiring an optical image. It should be noted that the lenses are omitted in FIGs. 3, 5, 6, 8 to 15.
  • the lens holder 200 is provided on the support surface 110 of the base 100 such that it can move relative to the base 100 in a direction parallel to the support surface 110.
  • the lens holder 200 includes: an auto focusing part 210 operatively associated with the optical lenses 300; and a movable frame 220 which fixedly receives the auto focusing part 210.
  • the actuators 410, 420, 430, 440 are used to move the lens holder 200 relative to the base 100.
  • the actuators 410, 420, 430, 440 respectively comprise a first to fourth shape memory alloy wire (hereinafter, referred to as "SMA wire” ) 412, 422, 432, 442.
  • SMA wire first to fourth shape memory alloy wire
  • the SMA wire 412, 422, 432, 442 change its length by energizing, in this case, by passing an electric current therethrough.
  • the SMA wire 412, 422, 432, 442 generates a driving force for moving the lens holder 200.
  • the OIS system 10 further comprises a plurality of wire turning elements. More specifically, the OIS system 10 comprises: a first pair of wire turning elements 510a, 510b, 510c; a second pair of wire turning elements 520a, 520b, 520c; a third pair of wire turning elements 530a, 530b, 530c; and a fourth pair of wire turning elements 540a, 540b, 540c.
  • the first pair of wire turning elements 510a, 510b, 510c is associated with the first actuator 410 (i.e., first SMA wire 412) .
  • the second pair of wire turning elements 520a, 520b, 520c is associated with the second actuator 420 (i.e., second SMA wire 422) .
  • the third pair of wire turning elements 530a, 530b, 530c is associated with the third actuator 430 (i.e., third SMA wire 432) .
  • the fourth pair of wire turning elements 540a, 540b, 540c is associated with the fourth actuator 440 (i.e., fourth SMA wire 442) .
  • the first to fourth SMA wires 412, 422, 432, 442 are respectively arranged at least once, in this embodiment three times, turned using the respective wire turning elements. That is, the first SMA wire 412 is turned three times using the first pair of wire turning elements 510a, 510b, 510c. Similarly, the second SMA wire 422 is turned three times using the second pair of wire turning elements 520a, 520b, 520c. The third SMA wire 432 is turned three times using the third pair of wire turning elements 530a, 530b, 530c. The fourth SMA wire 442 is turned three times using the fourth pair of wire turning elements 540a, 540b, 540c.
  • each pair of wire turning elements comprises two base-side wire turning elements and one holder-side wire turning element. More specifically, the first pair of wire turning elements comprises two base-side wire turning elements 510a, 510b provided on the base 100, and one holder-side wire turning element 510c provided on the lens holder 200. Similarly, the second pair of wire turning elements comprises two base-side wire turning elements 520a, 520b provided on the base 100, and one holder-side wire turning element 520c provided on the lens holder 200. The third pair of wire turning elements comprises two base-side wire turning elements 530a, 530b provided on the base 100, and one holder-side wire turning element 530c provided on the lens holder 200. The fourth pair of wire turning elements comprises two base-side wire turning elements 540a, 540b provided on the base 100, and one holder-side wire turning element 540c provided on the lens holder 200.
  • Each of the holder-side wire turning elements 510c, 520c, 530c, 540c are arranged between the related two base-side wire turning elements along an extension direction of the first to fourth SMA wire 412, 422, 432, 442. More specifically, the holder-side wire turning element 510c is arranged between the two base-side wire turning elements 510a, 510b. Similarly, the holder-side wire turning element 520c is arranged between the two base-side wire turning elements 520a, 520b. The holder-side wire turning element 530c is arranged between the two base-side wire turning elements 530a, 530b. The holder-side wire turning element 540c is arranged between the two base-side wire turning elements 540a, 540b.
  • each of the holder-side wire turning elements 510c, 520c, 530c, 540c are arranged on a respective corner of the movable frame 220 of the lens holder 200.
  • a position of the holder-side wire turning elements 510c, 520c, 530c, 540c on the lens holder 200 is arbitrary. The same applies to each base-side wire turning elements on the base 100.
  • Each of the SMA wires 412, 422, 432, 442 extends around the lens holder 200 in a substantially looped fashion through the two base-side wire turning elements and the holder-side wire turning element. More specifically, the first SMA wire 412 extends around the lens holder 200 through the two base-side wire turning elements 510a, 510b and the holder-side wire turning element 510c. Similarly, the second SMA wire 422 extends around the lens holder 200 through the two base-side wire turning elements 520a, 520b and the holder-side wire turning element 520c. The third SMA wire 432 extends around the lens holder 200 through the two base-side wire turning elements 530a, 530b and the holder-side wire turning element 530c. The fourth SMA wire 442 extends around the lens holder 200 through the two base-side wire turning elements 540a, 540b and the holder-side wire turning element 540c.
  • the movable frame 220 of the lens holder 200 includes linear grooves 220a to 220d on its four peripheral sides in order to accommodate at least a portion of the wire redirected with various turning elements (i.e., in order to avoid interference between the lens holder and the wire) .
  • the groove 220a accommodates a portion of the shape memory alloy wire 422, 432, as can be best seen in FIG. 2, and so on for the other grooves 220b to 220d.
  • each of the base-side wire turning elements 510a, 510b, 520a, 520b, 530a, 530b, 540a, 540b is a pulley provided on the base 100. These pulleys are rotatable about a respective axis (not indicated by a reference numeral) that projects from the support surface 110 of the base 100.
  • each of the holder-side wire turning elements 510c, 520c, 530c, 540c is a pulley rotatably provided on the lens holder 200.
  • the two base-side wire turning elements 540a, 540b and the holder-side wire turning element 540c are arranged such that a first virtual line L 1 connecting the two base-side wire turning elements 540a, 540b with each other and a second virtual line L 2 connecting the holder-side wire turning element 540c and a midpoint P of the first virtual line L 1 , are orthogonal to each other.
  • two base-side wire turning elements 510a, 510b, 520a, 520b, 530a, 530b and the holder-side wire turning element 510c, 520c, 530c have the same positional relationship, but are arranged 90 degrees apart from each other.
  • FIG. 4 shows metal clamp plates 632a, 632b for fourth SMA wire 432.
  • Each of the studs 612, 622, 632, 642 is shared by two ends of the respective SMA wire 412, 422, 432, 442.
  • Each of the SMA wires 412, 422, 432, 442 is energized through the stud 612, 622, 632, 642, more specifically, through a respective pair of metal clamp plates.
  • one of the plates is set as the positive pole and the other of the plates is set as the negative pole.
  • the OIS system 10 comprises four actuators 410, 420, 430, 440. That is, the OIS system 10 comprises first to fourth SMA wires 412, 422, 432, 442. Adjacent ones of these four actuators 410, 420, 430, 440, and thus, first to fourth SMA wires 412, 422, 432, 442 are arranged approximately 90 degrees apart from each other. The first to fourth SMA wire 412, 422, 432, 442 are arranged so that their heights from the support surface 110 of the base 100 are slightly different in order to avoid mutual interference.
  • each wire turning element i.e., each pulley 510a, 510b, 510c, 520a, 520b, 520c, 530a, 530b, 530c, 540a, 540b, 540c has an annular groove on its peripheral surface for receiving an associated wire of the SMA wires 412, 422, 432, 442.
  • Fig. 4 only shows an annular groove 512c of the pulley 510c, an annular groove 522a of the pulley 520a, and an annular groove 542b of the pulley 540b.
  • the height positions of the annular groove of each pulley from the support surface 110 of the base 10 are properly differentiated from each other so that mutual interference between different SMA wires is prevented.
  • the first SMA wire 412 is located at the top, that is, furthest from the support surface 110 of the base 100.
  • the first SMA wire 412 surrounds the lens holder 200 as well as the stoppers 130a, 130b, 130g, 130h.
  • the second SMA wire 422 is located just below the first SMA wire 412.
  • the second SMA wire 422 surrounds the lens holder 200 as well as the stoppers 130a, 130b, 130c, 130d.
  • the third SMA wire 432 is located just below the second SMA wire 422.
  • the third SMA wire 432 surrounds the lens holder 200 as well as the stoppers 130c, 130d, 130e, 130f.
  • the fourth SMA wire 442 is located at the bottom, that is, closest to the support surface 110 of the base 100.
  • the fourth SMA wire 442 surrounds the lens holder 200 as well as the stoppers 130e, 130f, 130g, 130h.
  • the OIS system 10 comprises a number of actuators, and thus SMA wires, less than or greater than four.
  • the actuators, and thus the SMA wires are separated by an appropriate angle depending on their number.
  • the positions of the wire turning elements are also adjusted appropriately.
  • the OIS system 10 further comprises a leaf spring 700.
  • the leaf spring 700 has an almost S-shape and includes central opening 710 for exposing the lenses received in the lens holder 200.
  • the leaf spring 700 is interposed between the base 100 and the lens holder 200.
  • the lens holder 200 is supported and urged to a central position thereof by the leaf spring 700.
  • three ball bearings 720a, 720b, 720c are further interposed between the support surface of the base 10 and the leaf spring 700.
  • the lens holder 200 including the AF part 210 is to be displaced upward as indicated by "Up" in FIG. 6 for an optical image stabilization
  • only the first and second SMA wires 412, 422 are energized at a high level (i.e., the temperature thereof is greatly raised) as show in FIG. 7.
  • the force to the upper left is applied to the lens holder 200 by the first SMA wire 412
  • the force to the upper right is applied simultaneously to the lens holder 200 by the second SMA wire 422.
  • the forces acting in the left and right directions are canceled out, and as a result, the lens holder 200 is moved only upward as shown in FIG. 8.
  • the unenergized wires 432, 442 are forcibly stretched by the energized wires 412, 422 (this also applies to the other operations described below) .
  • the lens holder 200 When the lens holder 200 is to be displaced to the upper right as indicated by "Up-Right" in FIG. 6 for an optical image stabilization, only the second SMA wire 422 is energized at a high level as show in FIG. 7.
  • the first and third SMA wires 412, 432 are energized at a low level (i.e., the temperature thereof is raised by a small amount) also as show in FIG. 7.
  • the force to the upper right is applied to the lens holder 200 by the second SMA wire 422
  • the force to the upper left is simultaneously applied to the lens holder 200 by the first SMA wire 412
  • the force to the lower right is also simultaneously applied to the lens holder 200 by the third SMA wire 432.
  • the forces due to the first and third SMA wires 412, 432 are balanced, and as a result, the lens holder 200 is moved to the upper right as shown in FIG. 12.
  • the lens holder 200 When the lens holder 200 is to be displaced to the lower right as indicated by "Down-Right" in FIG. 6 for an optical image stabilization, only the third SMA wire 432 is energized at a high level as show in FIG. 7. On the other hand, the second and fourth SMA wires 422, 432 are energized at a low level also as show in FIG. 7. Then, the force to the lower right is applied to the lens holder 200 by the third SMA wire 432, the force to the upper right is simultaneously applied to the lens holder 200 by the second SMA wire 422, and the force to the lower left is also simultaneously applied to the lens holder 200 by the fourth SMA wire 442. However, the forces due to the second and fourth SMA wires 422, 442 are balanced, and as a result, the lens holder 200 is moved to the lower right as shown in FIG. 13.
  • the lens holder 200 When the lens holder 200 is to be displaced to the upper left as indicated by "Up-Left" in FIG. 6 for an optical image stabilization, only the first SMA wire 412 is energized at a high level as show in FIG. 7.
  • the second and fourth SMA wires 422, 442 are energized at a low level also as show in FIG. 7. Then, the force to the upper left is applied to the lens holder 200 by the first SMA wire 412, the force to the upper right is simultaneously applied to the lens holder 200 by the second SMA wire 422, and the force to the lower left is also simultaneously applied to the lens holder 200 by the fourth SMA wire 442.
  • the forces due to the second and fourth SMA wires 422, 442 are balanced, and as a result, the lens holder 200 is moved to the upper left as shown in FIG. 14.
  • the fourth SMA wire 442 is energized at a high level as show in FIG. 7.
  • the first and third SMA wires 412, 432 are energized at a low level also as show in FIG. 7. Then, the force to the lower left is applied to the lens holder 200 by the fourth SMA wire 442, the force to the upper left is simultaneously applied to the lens holder 200 by the first SMA wire 412, and the force to the lower right is also simultaneously applied to the lens holder 200 by the third SMA wire 432.
  • the forces due to the first and third SMA wires 412, 432 are balanced, and as a result, the lens holder 200 is moved to the lower left as shown in FIG. 15. As will be appreciated by those skilled in the art upon reading this specification, the lens holder 200 is free to take positions other than those shown in FIGs. 8 to 15.
  • an optical image stabilization method to be implemented in the OIS system 10 comprises a step of operating at least one of the four actuators 410, 420, 430, 440 for moving the lens holder 200 relative to the base 100 in a direction needed for an optical image stabilization, by energizing at least one of the first to fourth SMA wires 412, 422, 432, 442 of the actuators 410, 420, 430, 440. More specifically, in the operating step, two or three actuators of the four actuators 410, 420, 430, 440 are operated simultaneously and in cooperation, as will be understood from the above description.
  • the SMA wires 412, 422, 432, 442 forming the actuators 410, 420, 430, 440 are connected to the lens holder 200 via respective wire turning elements, and drive the lens holder 200 in a desired direction. Therefore, the total length of the SMA wire 412, 422, 432, 442 can be made longer according to the number of times of turning, as compared with the conventional actuator that does not have such a configuration.
  • the OIS system 10 described above (this can be referred to as a "long stroke" OIS system) is particularly suitable for being incorporated into products, for example mobile electronic devices, that have a camera module that requires the agile movement of large, heavy lenses with long strokes within a limited small space.
  • the OIS system 10 incorporated in such a product provides high image stabilization and image stitching functions.
  • the OIS system according to the above described embodiment can be significantly downsized as compared to the VCM (voice coil motor) type OIS system, and unlike that, the problem of magnetic interference does not occur.

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Abstract

An optical image stabilization system (10). The system (100) comprises: a base (100) having a support surface (110); a lens holder (200) that holds at least one optical lens (300) for acquiring an optical image, wherein the lens holder (200) is provided on the base (100) such that it can move relative to the base (100) in a direction parallel to the support surface (110) of the base (100) ; at least one actuator (410; 420; 430; 440) for moving the lens holder (200) relative to the base (100) , wherein the actuator (410; 420; 430; 440) comprises a shape memory alloy wire (412; 422; 432; 442) whose length changes by being energized. The system (10) further comprises at least one wire turning element (510a, 510b, 510c; 520a, 520b, 520c; 530a, 530b, 530c; 540a, 540b, 540c) . The shape memory alloy wire (412; 422; 432; 442) is arranged so as to be turned at least once using the wire turning element (510a, 510b, 510c; 520a, 520b, 520c; 530a, 530b, 530c; 540a, 540b, 540c) . An optical image stabilization method to be implemented in such a system. A product (1) including a camera module (1a) , which also comprises the optical image stabilization system (10).

Description

LONG STROKE OPTICAL IMAGE STABILIZATION SYSTEM AND METHOD [TECHNICAL FIELD]
The present invention relates to a long stroke optical image stabilization system and method. Especially, the present invention relates to a long stroke optical image stabilization system and method to be used in a camera module or a camera unit of various products, in particular, various mobile electronic devices including smartphones, mobile phones, etc. The present invention also relates to a product including such an optical image stabilization system.
[BACKGROUND ART]
In recent years, there has been a trend that the size of an image sensor which is mounted on a camera module of a smartphone or a mobile phone is getting bigger and bigger. Along with this, its lens size is also getting bigger in order to cope with the increase in the size of the image sensor. As a result, the lens weight is further increased.
The camera module contains an optical image stabilization (hereinafter, referred to as "OIS" ) system, as is well known to those skilled in the art. The OIS system is intended to enhance a photo capability, and this capability becomes one of the major functionalities in a smartphone or a mobile phone, etc.
However, the OIS system may also increase the lens weight. This is because a wider imaging area needs to be provided in order to realize the functionality as stated above. In this case, a lens actuator installed in the camera module needs to move such a heavy lens in order to realize the functionality of the OIS system. On the other  hand, the size of the actuator is constrained due to the limited installation space inside a smartphone or a mobile phone.
In order to improve the functionality of the OIS system, a sufficient physical space is required for a movement of the lens, since the target lens moves in a wider range in order to compensate a hand-blur. However, as stated above, since the space inside a smartphone or a mobile phone is limited, there is a demand for efficient way to effectively use the space.
Presently, with regard to a camera module of a smartphone or a mobile phone, the OIS system of a voice coil motor (hereinafter, referred to as "VCM" ) type is a major solution to this demand. The VCM is mainly composed of a coil and a magnet. The VCM is a drive unit that obtains a thrust force by passing an electric current through the coil.
As another solution, the OIS system of a shape memory alloy (hereinafter, referred to as "SMA" ) type is also known. A wire manufactured from SMA has a characteristic of deforming, for example expanding or contracting, when its temperature is raised by the application of electric current, as is well known to those skilled in the art. This characteristic of the SMA wire is used to drive the lens.
As stated above, although the OIS system of the VCM type is major solution in the camera module of a smartphone or a mobile phone, it is necessary to increase the size of the coil and the magnet which consists the VCM in order to correspond a heavy weight of the lens. In the OIS system of the VCM type, a further expansion of the coil and the magnet is necessary to achieve longer stroke of the optical lens. In  addition to this, the OIS system of the VCM type has a problem in relation to a magnetic interference.
The OIS system of the SMA wire type produces a large thrust force, and thus can easily drive a heavy lens. In addition to this, contrary to the OIS system of the VCM type, the OIS system of the SMA wire type has no problem in relation to magnetic interference. However, due to the inherent characteristics of the SMA wire, existing SMA wire type systems are not suitable for a long stroke operation of the optical lens.
Conventional techniques considered to be somewhat related to the present invention are disclosed, for example, in JP2018018083A and JP2015518977A.
JP2018018083A discloses a lens driver that is configured to move a lens using a shape memory alloy (SMA) wire. This device includes: a first drive mechanism for moving a lens holder along an optical axis of the lens; and a second drive mechanism including a SMA wire assembly electrically connected to a circuit board. JP2015518977A also discloses a lens driver that uses a SMA wire for realizing an optical image stabilization (OIS) effect. However, these conventional devices are also unable to achieve the long stroke operation demanded today within the limited small space.
For these reasons, there is a demand for an optical image stabilization system and method that can realize a longer stroke of the optical lens than prior art devices within a limited small space.
[DISCLOSURE OF INVENTION]
In view of the above, an object of the present invention is to provide a novel optical image stabilization system and method which can overcome or at least alleviate the problems stated above in relation to the prior art devices. In particular, a  more specific object of the present invention is to provide a novel optical image stabilization system and method that can realize a longer stroke of the optical lens than prior art devices within a limited small space without magnetic interference.
In order to achieve these objects, the present invention provides an optical image stabilization system, comprising: a base having a support surface; a lens holder that holds at least one optical lens for acquiring an optical image, wherein the lens holder is provided on the base such that it can move relative to the base in a direction parallel to the support surface of the base; at least one actuator for moving the lens holder relative to the base, wherein the actuator comprises a shape memory alloy wire whose length changes by being energized, wherein the optical image stabilization system further comprises at least one wire turning element, and wherein the shape memory alloy wire is arranged so as to be turned at least once using the wire turning element.
The present invention also provides an optical image stabilization method to be implemented in the system as stated above, the method comprising a step of: operating the at least one actuator for moving the lens holder relative to the base in a direction needed for an image stabilization, by energizing the shape memory alloy wire of the at least one actuator. The present invention further provides a product including a camera module, wherein the camera module comprises the optical image stabilization system as stated above.
According to the present invention, the shape memory alloy wire forming the actuator is connected to the lens holder via at least one wire turning element and can drive the lens holder in a desired direction. Therefore, according to the present invention, the total length of the shape memory alloy wire can be made longer according to the  number of times of turning, as compared with the conventional actuator that does not have such a configuration. This increases the total amount of deformation of the shape memory alloy wire (i.e., a stroke of the actuator) , and as a result, an amount of movement of the lens holder connected to the shape memory alloy wire can be significantly increased as compared with a conventional actuator.
The optical image stabilization system according to the present invention is particularly suitable for being incorporated into products, for example the latest mobile electronic devices, that have a camera module that requires the movement of large, heavy lenses with long strokes within a limited small space.
As used herein, the term "turning" means changing the direction of the shape memory alloy wire at a certain point. The angle between a wire section before the direction thereof is changed and a wire section after the direction thereof is changed may be 45° to 135°, preferably 60° to 120°, particularly preferably 80° to 100°, for example 85° to 95°.
According to one preferred aspect of the present invention, the at least one wire turning element may comprise: two base-side wire turning elements provided on the base; and a holder-side wire turning element provided on the lens holder, wherein the holder-side wire turning element is arranged between the two base-side wire turning elements along an extension direction of the shape memory alloy wire. In this preferred aspect, the shape memory alloy wire extends around the lens holder in a substantially looped fashion through the two base-side wire turning elements and the holder-side wire turning element.
According to one preferred aspect of the present invention, the two base-side wire turning elements and the holder-side wire turning element may be arranged such that a first virtual line connecting the two base-side wire turning elements with each other and a second virtual line connecting the holder-side wire turning element and a midpoint of the first virtual line, are orthogonal to each other. That is, in this preferred aspect, the two base-side wire turning elements are arranged symmetrically with the second virtual line in between. This aspect provides a particularly good balance of driving forces of the actuator.
According to one preferred aspect of the present invention, the base-side wire turning element may be a pulley rotatably provided on the base. Similarly, the holder-side wire turning element may be a pulley rotatably provided on the lens holder. Alternatively, the base-side wire turning element and/or the holder-side wire turning element may be a boss having, for example, a circular cross section. In this case, the outer peripheral surface of the boss is preferably subjected to a friction reduction treatment (using
Figure PCTCN2020114969-appb-000001
for example) .
According to one preferred aspect of the present invention, two ends of the shape memory alloy wire may be fixed to a stud protruding from the support surface of the base. In this preferred aspect, the stud is shared by two ends of the shape memory alloy wire. Furthermore, in this preferred aspect, the shape memory alloy wire may be energized through the shared stud. In this case, the electrical wiring architecture for supplying power to the shape memory alloy wire can be particularly simplified. In addition to this, the stud may be provided at a corner of the base. In this case, the stud is  preferably arranged on the extension of the second virtual line connecting the holder-side wire turning element and the midpoint of the first virtual line.
According to one preferred aspect of the present invention, the optical image stabilization system may comprise a plurality of, in particular, four actuators operable independently of each other. In this case, adjacent ones of the four actuators are arranged approximately 90 degrees apart from each other. In the present invention, this aspect is particularly preferred. This is because by adopting this configuration, the lens holder can be freely moved with respect to the base (for example, upward or downward, left or right, and a combination thereof) . In this aspect, corresponding to the number of the actuators, the required number (i.e., four) of pairs of the holder-side wire turning elements and the base-side wire turning elements are provided. Furthermore, in this preferred aspect of the present invention, each pulley may have an annular groove on its peripheral surface for receiving an associated wire. In this case, the height positions of the annular groove of each pulley from the support surface of the base may be different from each other so that mutual interference between different wires is prevented.
According to one preferred aspect of the present invention, the lens holder may include: an auto focusing part operatively associated with the at least one optical lens; and a movable frame which fixedly receives the auto focusing part. In this case, the holder-side wire turning element (s) may be arranged on the movable frame.
According to one preferred aspect of the present invention, the optical image stabilization system may further comprises a leaf spring interposed between the base and the lens holder. In this case, the lens holder is supported and urged to a central position thereof by the leaf spring. The spring shape is not particularly limited, but, for  example, an S-shaped one having a circular opening for exposing the lens in the center thereof can be used.
With regard to the optical image stabilization method, according to one preferred aspect of the present invention, the system to be used to implement this method may comprise four actuators arranged approximately 90 degrees apart from each other. In this case, in the operating step, two or three actuators of the four actuators are operated simultaneously. By this, as stated above, the lens holder can be freely moved with respect to the base (for example, upward or downward, left or right, and a combination thereof) .
With regard to the product including a camera module, according to one preferred aspect of the present invention, the product may be a device, an apparatus, an equipment, a machine, a facility, a tool, or the like, which includes the camera module. In particular, the product may be a mobile electronic device including the camera module.
[BRIEF DESCRIPTION OF THE DRAWINGS]
Non-limiting and representative embodiments of the present invention will now be explained in detail below referring to the attached drawings.
FIG. 1 is a schematic view of a product, i.e., a smartphone that incorporates an optical image stabilization (OIS) system according to one embodiment of the present invention.
FIG. 2 is a plane view of the OIS system shown in FIG. 1.
FIG. 3 is a perspective view of the OIS system shown in FIG. 1 in the disassembled state.
FIG. 4 is a perspective view of the corner area of the OIS system shown in FIG. 1.
FIG. 5 is a plane view of the OIS system shown in FIG. 1, showing the positional relationship of various pulleys that guide a shape memory alloy (SMA) wire, wherein the SMA wires are shown in phantom line.
FIG. 6 is a plane view of the OIS system shown in FIG. 1, indicating eight movement directions of the lens holder, wherein a leaf spring is omitted for clarity.
FIG. 7 is a table showing the relationship between the degree of energizing (heating) of each SMA wire and a moving direction of the lens holder.
FIG. 8 is a plane view of the OIS system shown in FIG. 1, showing a state in which the lens holder has been moved upward by the operation of some related actuators.
FIG. 9 is a plane view of the OIS system shown in FIG. 1, showing a state in which the lens holder has been moved to the downward by the operation of some related actuators.
FIG. 10 is a plane view of the OIS system shown in FIG. 1, showing a state in which the lens holder has been moved to the right side by the operation of some related actuators.
FIG. 11 is a plane view of the OIS system shown in FIG. 1, showing a state in which the lens holder has been moved to the left side by the operation of some related actuators.
FIG. 12 is a plane view of the OIS system shown in FIG. 1, showing a state in which the lens holder has been moved upper right by the operation of some related actuators.
FIG. 13 is a plane view of the OIS system shown in FIG. 1, showing a state in which the lens holder has been moved lower right by the operation of some related actuators.
FIG. 14 is a plane view of the OIS system shown in FIG. 1, showing a state in which the lens holder has been moved upper left by the operation of some related actuators.
FIG. 15 is a plane view of the OIS system shown in FIG. 1, showing a state in which the lens holder has been moved lower left by the operation of some related actuators.
[DETAILED DESCRIPTION OF EMBODIMENTS]
Some exemplary embodiments of the present invention will now be described with reference to FIGs. 1 to 15.
As used herein, terms related to the direction such as "up" , "down" , "upper" , "lower" , "upward" , "downward" , "right" , "left" , etc. are to be understood in relation to the orientation of the system in the figures, which may or may not match the actual orientation in use.
The following exemplary embodiments of the present invention relate to an optical image stabilization system and method to be used in a camera module, but not limited thereto, of the products like a mobile electronic device, in particular a smartphones. Furthermore, the following exemplary embodiments of the present invention also relate to such products, in particular a mobile electronic device, including a camera module which comprises the optical image stabilization system being one exemplary embodiment of the present invention. However, the product can be any device, any apparatus, any equipment, any machine, any facility, any tool, or the like, which includes a camera module.
FIG. 1 shows a mobile electronic device 1, that is, a smartphones according to one preferred embodiment of the present invention. The mobile electronic device 1 includes a camera module 1a which is built into it. The camera module 1a comprises an optical image stabilization system (hereinafter, referred to as "OIS system" )  10 as detailed below.
FIG. 2 shows a plane view of the OIS system 10. The OIS system 10 mainly comprises: a base 100; a lens holder 200; and a plurality of, in particular, four, i.e., first to  fourth actuators  410, 420, 430, 440 operable independently of each other. As can be best seen from FIG. 3, which is a perspective view of the OIS system 10 in the disassembled state, the base 100 has a support surface 110. The base 100 has a circular opening 120 for exposing a lens (described below) received in the lens holder 200. From the support surface 110, a plurality of plate-shaped stoppers 130a to 130h project so as to surround the circular opening 120. The stoppers 130a to 130h cooperatively define a substantially square movable area of the lens holder 200.
The lens holder 200 holds at least one, in this embodiment, two, three, or four optical lenses 300 for acquiring an optical image. It should be noted that the lenses are omitted in FIGs. 3, 5, 6, 8 to 15. The lens holder 200 is provided on the support surface 110 of the base 100 such that it can move relative to the base 100 in a direction parallel to the support surface 110. In this embodiment, as can be best seen from FIG. 3, the lens holder 200 includes: an auto focusing part 210 operatively associated with the optical lenses 300; and a movable frame 220 which fixedly receives the auto focusing part 210.
The  actuators  410, 420, 430, 440 are used to move the lens holder 200 relative to the base 100. In this embodiment, the  actuators  410, 420, 430, 440 respectively comprise a first to fourth shape memory alloy wire (hereinafter, referred to as "SMA wire" ) 412, 422, 432, 442. As is well known to those skilled in the art, the  SMA wire  412, 422, 432, 442 change its length by energizing, in this case, by passing an electric current therethrough. As a result, the  SMA wire  412, 422, 432, 442 generates a driving force for moving the lens holder 200.
In addition to FIGs. 2 to 4, also as can be seen from FIG 5, the OIS system 10 further comprises a plurality of wire turning elements. More specifically, the OIS system 10 comprises: a first pair of  wire turning elements  510a, 510b, 510c; a second pair of  wire turning elements  520a, 520b, 520c; a third pair of  wire turning elements  530a, 530b, 530c; and a fourth pair of  wire turning elements  540a, 540b, 540c. The first pair of  wire turning elements  510a, 510b, 510c is associated with the first actuator 410 (i.e., first SMA wire 412) . The second pair of  wire turning elements  520a, 520b, 520c is associated with the second actuator 420 (i.e., second SMA wire 422) . The third pair of  wire turning  elements  530a, 530b, 530c is associated with the third actuator 430 (i.e., third SMA wire 432) . The fourth pair of  wire turning elements  540a, 540b, 540c is associated with the fourth actuator 440 (i.e., fourth SMA wire 442) .
The first to  fourth SMA wires  412, 422, 432, 442 are respectively arranged at least once, in this embodiment three times, turned using the respective wire turning elements. That is, the first SMA wire 412 is turned three times using the first pair of  wire turning elements  510a, 510b, 510c. Similarly, the second SMA wire 422 is turned three times using the second pair of  wire turning elements  520a, 520b, 520c. The third SMA wire 432 is turned three times using the third pair of  wire turning elements  530a, 530b, 530c. The fourth SMA wire 442 is turned three times using the fourth pair of  wire turning elements  540a, 540b, 540c.
In this embodiment, each pair of wire turning elements comprises two base-side wire turning elements and one holder-side wire turning element. More specifically, the first pair of wire turning elements comprises two base-side  wire turning elements  510a, 510b provided on the base 100, and one holder-side wire turning element 510c provided on the lens holder 200. Similarly, the second pair of wire turning elements comprises two base-side  wire turning elements  520a, 520b provided on the base 100, and one holder-side wire turning element 520c provided on the lens holder 200. The third pair of wire turning elements comprises two base-side  wire turning elements  530a, 530b provided on the base 100, and one holder-side wire turning element 530c provided on the lens holder 200. The fourth pair of wire turning elements comprises two base-side  wire turning elements  540a, 540b provided on the base 100, and one holder-side wire turning element 540c provided on the lens holder 200.
Each of the holder-side  wire turning elements  510c, 520c, 530c, 540c are arranged between the related two base-side wire turning elements along an extension direction of the first to  fourth SMA wire  412, 422, 432, 442. More specifically, the holder-side wire turning element 510c is arranged between the two base-side  wire turning elements  510a, 510b. Similarly, the holder-side wire turning element 520c is arranged between the two base-side  wire turning elements  520a, 520b. The holder-side wire turning element 530c is arranged between the two base-side  wire turning elements  530a, 530b. The holder-side wire turning element 540c is arranged between the two base-side  wire turning elements  540a, 540b.
In this exemplary embodiment, each of the holder-side  wire turning  elements  510c, 520c, 530c, 540c are arranged on a respective corner of the movable frame 220 of the lens holder 200. However, a position of the holder-side  wire turning elements  510c, 520c, 530c, 540c on the lens holder 200 is arbitrary. The same applies to each base-side wire turning elements on the base 100.
Each of the  SMA wires  412, 422, 432, 442 extends around the lens holder 200 in a substantially looped fashion through the two base-side wire turning elements and the holder-side wire turning element. More specifically, the first SMA wire 412 extends around the lens holder 200 through the two base-side  wire turning elements  510a, 510b and the holder-side wire turning element 510c. Similarly, the second SMA wire 422 extends around the lens holder 200 through the two base-side  wire turning elements  520a, 520b and the holder-side wire turning element 520c. The third SMA wire 432 extends around the lens holder 200 through the two base-side  wire turning elements  530a, 530b and the holder-side wire turning element 530c. The fourth SMA wire 442 extends around the lens holder 200 through the two base-side  wire turning elements  540a, 540b and the holder-side wire turning element 540c.
As can be seen from FIG. 3, the movable frame 220 of the lens holder 200 includes linear grooves 220a to 220d on its four peripheral sides in order to accommodate at least a portion of the wire redirected with various turning elements (i.e., in order to avoid interference between the lens holder and the wire) . For example, the groove 220a accommodates a portion of the shape  memory alloy wire  422, 432, as can be best seen in FIG. 2, and so on for the other grooves 220b to 220d.
In this embodiment, as can be best seen from FIG. 4, each of the base-side  wire turning elements  510a, 510b, 520a, 520b, 530a, 530b, 540a, 540b is a pulley provided on the base 100. These pulleys are rotatable about a respective axis (not indicated by a reference numeral) that projects from the support surface 110 of the base 100. Similarly, each of the holder-side  wire turning elements  510c, 520c, 530c, 540c is a pulley rotatably provided on the lens holder 200.
The positional relationship between the two base-side wire turning elements and the holder-side wire turning element will be described by taking the case of the fourth actuator 440 as an example. As shown in FIG. 5, the two base-side  wire turning elements  540a, 540b and the holder-side wire turning element 540c are arranged such that a first virtual line L 1 connecting the two base-side  wire turning elements  540a, 540b with each other and a second virtual line L 2 connecting the holder-side wire turning  element 540c and a midpoint P of the first virtual line L 1, are orthogonal to each other. Regarding the first to  third actuators  410, 420, 430 as well, two base-side  wire turning elements  510a, 510b, 520a, 520b, 530a, 530b and the holder-side  wire turning element  510c, 520c, 530c have the same positional relationship, but are arranged 90 degrees apart from each other.
As can be seen from FIG. 4, two ends of the  SMA wire  412, 422, 432, 442 are fixed to a  respective stud  612, 622, 632, 642 protruding from the support surface 110 of the base 100. The  studs  612, 622, 632, 642 are provided at a respective corner of the base 100. In this embodiment, fixing of the SMA wires is done using a pair of metal clamp plates. FIG. 4 shows  metal clamp plates  632a, 632b for fourth SMA wire 432. Each of the  studs  612, 622, 632, 642 is shared by two ends of the  respective SMA wire  412, 422, 432, 442. Each of the  SMA wires  412, 422, 432, 442 is energized through the  stud  612, 622, 632, 642, more specifically, through a respective pair of metal clamp plates. In this case, one of the plates is set as the positive pole and the other of the plates is set as the negative pole.
As stated above, in this exemplary embodiment, the OIS system 10 comprises four  actuators  410, 420, 430, 440. That is, the OIS system 10 comprises first to  fourth SMA wires  412, 422, 432, 442. Adjacent ones of these four  actuators  410, 420, 430, 440, and thus, first to  fourth SMA wires  412, 422, 432, 442 are arranged approximately 90 degrees apart from each other. The first to  fourth SMA wire  412, 422, 432, 442 are arranged so that their heights from the support surface 110 of the base 100 are slightly different in order to avoid mutual interference. More specifically, each wire turning element, i.e., each  pulley  510a, 510b, 510c, 520a, 520b, 520c, 530a, 530b, 530c, 540a, 540b, 540c has an annular groove on its peripheral surface for receiving an associated wire of the  SMA wires  412, 422, 432, 442. Fig. 4 only shows an annular groove 512c of the pulley 510c, an annular groove 522a of the pulley 520a, and an annular groove 542b of the pulley 540b. In this embodiment, for example, by adjusting the height of a receiving surface for each pulley provided on the base 10 and the movable frame 220, the height positions of the annular groove of each pulley from the support surface 110 of the base 10 are properly differentiated from each other so that mutual interference between different SMA wires is prevented.
More specifically, the first SMA wire 412 is located at the top, that is, furthest from the support surface 110 of the base 100. The first SMA wire 412 surrounds  the lens holder 200 as well as the  stoppers  130a, 130b, 130g, 130h. The second SMA wire 422 is located just below the first SMA wire 412. The second SMA wire 422 surrounds the lens holder 200 as well as the  stoppers  130a, 130b, 130c, 130d. The third SMA wire 432 is located just below the second SMA wire 422. The third SMA wire 432 surrounds the lens holder 200 as well as the  stoppers  130c, 130d, 130e, 130f. The fourth SMA wire 442 is located at the bottom, that is, closest to the support surface 110 of the base 100. The fourth SMA wire 442 surrounds the lens holder 200 as well as the  stoppers  130e, 130f, 130g, 130h.
In other embodiment, the OIS system 10 comprises a number of actuators, and thus SMA wires, less than or greater than four. In this case, the actuators, and thus the SMA wires are separated by an appropriate angle depending on their number. In addition to this, the positions of the wire turning elements are also adjusted appropriately.
Again referring to FIG. 3, the OIS system 10 further comprises a leaf spring 700. In this embodiment, the leaf spring 700 has an almost S-shape and includes central opening 710 for exposing the lenses received in the lens holder 200. The leaf spring 700 is interposed between the base 100 and the lens holder 200. The lens holder 200 is supported and urged to a central position thereof by the leaf spring 700. In this embodiment, three  ball bearings  720a, 720b, 720c are further interposed between the support surface of the base 10 and the leaf spring 700.
The operation of the above-stated OIS system 10 will be described below with reference to FIGs. 6 to 15. Note that in FIG. 7, "Hot" means that electric power is supplied at a high level, "Warm" means that electric power is supplied at a low level, and "Cold" means that electric power is not supplied.
First, when the lens holder 200 including the AF part 210 is to be displaced upward as indicated by "Up" in FIG. 6 for an optical image stabilization, only the first and  second SMA wires  412, 422 are energized at a high level (i.e., the temperature thereof is greatly raised) as show in FIG. 7. Then, the force to the upper left is applied to the lens holder 200 by the first SMA wire 412, and the force to the upper right is applied simultaneously to the lens holder 200 by the second SMA wire 422. However, the forces acting in the left and right directions are canceled out, and as a result, the lens holder 200 is moved only upward as shown in FIG. 8. At this time, the  unenergized wires  432, 442 are forcibly stretched by the energized wires 412, 422 (this also applies to the other operations described below) .
When the lens holder 200 is to be displaced downward as indicated by "Down" in FIG. 6 for an optical image stabilization, only the third and  fourth SMA wires  432, 442 are energized at a high level as show in FIG. 7. Then, the force to the lower right is applied to the lens holder 200 by the third SMA wire 432, and the force to the lower left is applied simultaneously to the lens holder 200 by the fourth SMA wire 442. However, the forces acting in the left and right directions are canceled out, and as a result, the lens holder 200 is moved only downward as shown in FIG. 9.
When the lens holder 200 is to be displaced to the right as indicated by "Right" in FIG. 6 for an optical image stabilization, only the second and  third SMA wires  422, 432 are energized at a high level as show in FIG. 7. Then, the force to the upper right is applied to the lens holder 200 by the second SMA wire 422, and the force to the lower right is applied simultaneously to the lens holder 200 by the third SMA wire 432. However, the forces acting in the upward and downward are canceled out, and as a result, the lens holder 200 is moved only to the right side as shown in FIG. 10.
When the lens holder 200 is to be displaced to the left as indicated by "Left" in FIG. 6 for an optical image stabilization, only the first and  fourth SMA wires  412, 442 are energized at a high level as show in FIG. 7. Then, the force to the upper left is applied to the lens holder 200 by the first SMA wire 412, and the force to the lower left is applied simultaneously to the lens holder 200 by the fourth SMA wire 442. However, the forces acting in the upward and downward are canceled out, and as a result, the lens holder 200 is moved only to the left side as shown in FIG. 11.
When the lens holder 200 is to be displaced to the upper right as indicated by "Up-Right" in FIG. 6 for an optical image stabilization, only the second SMA wire 422 is energized at a high level as show in FIG. 7. On the other hand, the first and  third SMA wires  412, 432 are energized at a low level (i.e., the temperature thereof is raised by a small amount) also as show in FIG. 7. Then, the force to the upper right is applied to the lens holder 200 by the second SMA wire 422, the force to the upper left is simultaneously applied to the lens holder 200 by the first SMA wire 412, and the force to the lower right is also simultaneously applied to the lens holder 200 by the third SMA wire 432. However, the forces due to the first and  third SMA wires  412, 432 are balanced, and as a result, the lens holder 200 is moved to the upper right as shown in FIG. 12.
When the lens holder 200 is to be displaced to the lower right as indicated by "Down-Right" in FIG. 6 for an optical image stabilization, only the third SMA wire 432  is energized at a high level as show in FIG. 7. On the other hand, the second and  fourth SMA wires  422, 432 are energized at a low level also as show in FIG. 7. Then, the force to the lower right is applied to the lens holder 200 by the third SMA wire 432, the force to the upper right is simultaneously applied to the lens holder 200 by the second SMA wire 422, and the force to the lower left is also simultaneously applied to the lens holder 200 by the fourth SMA wire 442. However, the forces due to the second and  fourth SMA wires  422, 442 are balanced, and as a result, the lens holder 200 is moved to the lower right as shown in FIG. 13.
When the lens holder 200 is to be displaced to the upper left as indicated by "Up-Left" in FIG. 6 for an optical image stabilization, only the first SMA wire 412 is energized at a high level as show in FIG. 7. On the other hand, the second and  fourth SMA wires  422, 442 are energized at a low level also as show in FIG. 7. Then, the force to the upper left is applied to the lens holder 200 by the first SMA wire 412, the force to the upper right is simultaneously applied to the lens holder 200 by the second SMA wire 422, and the force to the lower left is also simultaneously applied to the lens holder 200 by the fourth SMA wire 442. However, the forces due to the second and  fourth SMA wires  422, 442 are balanced, and as a result, the lens holder 200 is moved to the upper left as shown in FIG. 14.
Finally, when the lens holder 200 is to be displaced to the lower left as indicated by "Down-Left" in FIG. 6 for an optical image stabilization, only the fourth SMA wire 442 is energized at a high level as show in FIG. 7. On the other hand, the first and  third SMA wires  412, 432 are energized at a low level also as show in FIG. 7. Then, the force to the lower left is applied to the lens holder 200 by the fourth SMA wire 442, the force to the upper left is simultaneously applied to the lens holder 200 by the first SMA wire 412, and the force to the lower right is also simultaneously applied to the lens holder 200 by the third SMA wire 432. However, the forces due to the first and  third SMA wires  412, 432 are balanced, and as a result, the lens holder 200 is moved to the lower left as shown in FIG. 15. As will be appreciated by those skilled in the art upon reading this specification, the lens holder 200 is free to take positions other than those shown in FIGs. 8 to 15.
As described in detail above, an optical image stabilization method to be implemented in the OIS system 10, which is also one exemplary embodiment of the present invention, comprises a step of operating at least one of the four  actuators  410, 420,  430, 440 for moving the lens holder 200 relative to the base 100 in a direction needed for an optical image stabilization, by energizing at least one of the first to  fourth SMA wires  412, 422, 432, 442 of the  actuators  410, 420, 430, 440. More specifically, in the operating step, two or three actuators of the four  actuators  410, 420, 430, 440 are operated simultaneously and in cooperation, as will be understood from the above description.
As stated above, in the system and method according to the above described embodiment, the  SMA wires  412, 422, 432, 442 forming the  actuators  410, 420, 430, 440 are connected to the lens holder 200 via respective wire turning elements, and drive the lens holder 200 in a desired direction. Therefore, the total length of the  SMA wire  412, 422, 432, 442 can be made longer according to the number of times of turning, as compared with the conventional actuator that does not have such a configuration. This increases the total amount of deformation of the  SMA wires  412, 422, 432, 442 (i.e., a stroke of the  actuators  410, 420, 430, 440) , and as a result, an amount of movement of the lens holder 200 connected to the  SMA wires  412, 422, 432, 442 can be significantly increased as compared with a conventional actuator.
Accordingly, the OIS system 10 described above (this can be referred to as a "long stroke" OIS system) is particularly suitable for being incorporated into products, for example mobile electronic devices, that have a camera module that requires the agile movement of large, heavy lenses with long strokes within a limited small space. The OIS system 10 incorporated in such a product provides high image stabilization and image stitching functions. Furthermore, the OIS system according to the above described embodiment can be significantly downsized as compared to the VCM (voice coil motor) type OIS system, and unlike that, the problem of magnetic interference does not occur.
Preferred embodiments of the present invention have been explained above with reference to the related drawings. However, the present invention is not limited to these embodiments, and various modifications and changes may be made to the above-described embodiments without deviating from the gist and scope of the present invention, and such modifications and changes are also included in the scope of the present invention.

Claims (18)

  1. An optical image stabilization system (10) , comprising:
    a base (100) having a support surface (110) ;
    a lens holder (200) that holds at least one optical lens (300) for acquiring an optical image, wherein the lens holder (200) is provided on the base (100) such that it can move relative to the base (100) in a direction parallel to the support surface (110) of the base (100) ;
    at least one actuator (410; 420; 430; 440) for moving the lens holder (200) relative to the base (100) , wherein the actuator (410; 420; 430; 440) comprises a shape memory alloy wire (412; 422; 432; 442) whose length changes by being energized,
    wherein the optical image stabilization system (10) further comprises at least one wire turning element (510a, 510b, 510c; 520a, 520b, 520c; 530a, 530b, 530c; 540a, 540b, 540c) , and
    wherein the shape memory alloy wire (412; 422; 432; 442) is arranged so as to be turned at least once using the wire turning element (510a, 510b, 510c; 520a, 520b, 520c; 530a, 530b, 530c; 540a, 540b, 540c) .
  2. The optical image stabilization system (10) according to claim 1, wherein the at least one wire turning element (510a, 510b, 510c; 520a, 520b, 520c; 530a, 530b, 530c; 540a, 540b, 540c) comprises:
    two base-side wire turning elements (510a, 510b; 520a, 520b; 530a, 530b; 540a, 540b) provided on the base (100) ; and
    a holder-side wire turning element (510c; 520c; 530c; 540c) provided on the lens holder (200) , wherein the holder-side wire turning element (510c; 520c; 530c; 540c) is arranged between the two base-side wire turning elements (510a, 510b; 520a, 520b; 530a, 530b; 540a, 540b) along an extension direction of the shape memory alloy wire (412; 422; 432; 442) ,
    wherein the shape memory alloy wire (412; 422; 432; 442) extends around the lens holder (200) in a substantially looped fashion through the two base-side wire turning elements (510a, 510b; 520a, 520b; 530a, 530b; 540a, 540b) and the holder-side wire turning element (510c; 520c; 530c; 540c) .
  3. The optical image stabilization system (10) according to claim 2, wherein the two base-side wire turning elements (510a, 510b; 520a, 520b; 530a, 530b; 540a, 540b) and the holder-side wire turning element (510c; 520c; 530c; 540c) are arranged such that a first virtual line (L 1) connecting the two base-side wire turning elements (510a, 510b; 520a, 520b; 530a, 530b; 540a, 540b) with each other and a second virtual line (L 2) connecting the holder-side wire turning element (510c; 520c; 530c; 540c) and a midpoint (P) of the first virtual line (L 1) , are orthogonal to each other.
  4. The optical image stabilization system (10) according to claim 2 or 3, wherein the base-side wire turning element (510a, 510b; 520a, 520b; 530a, 530b; 540a, 540b) is a pulley rotatably provided on the base (100) .
  5. The optical image stabilization system (10) according to any one of claims 2 to 4, wherein the holder-side wire turning element (510c; 520c; 530c; 540c) is a pulley rotatably provided on the lens holder (200) .
  6. The optical image stabilization system (10) according to any one of the preceding claims, wherein two ends of the shape memory alloy wire (412; 422; 432; 442) are fixed to a stud (612; 622; 632; 642) protruding from the support surface (110) of the base (100) , and wherein the stud (612; 622; 632; 642) is shared by two ends of the shape memory alloy wire (412; 422; 432; 442) .
  7. The optical image stabilization system (10) according to claim 6, wherein the shape memory alloy wire (412; 422; 432; 442) is energized through the stud (612; 622; 632; 642) .
  8. The optical image stabilization system (10) according to claim 6 or 7, wherein the stud (612; 622; 632; 642) is provided at a corner of the base (100) .
  9. The optical image stabilization system (10) according to any one of the preceding claims, wherein the system (10) comprises four actuators (410; 420; 430; 440) operable independently of each other; and wherein adjacent ones of the four actuators (410; 420; 430; 440) are arranged approximately 90 degrees apart from each other.
  10. The optical image stabilization system (10) according to claim 9 when depending on claim 4 or 5, wherein each pulley has an annular groove on its peripheral surface for receiving an associated wire (412; 422; 432; 442) , and wherein the height positions of the annular groove of each pulley from the support surface (110) of the base (100) are different from each other so that mutual interference between different wires is prevented.
  11. The optical image stabilization system (10) according to any one of the preceding claims, wherein the lens holder (200) includes: an auto focusing part (210) operatively associated with the at least one optical lens (300) ; and a movable frame (220) which fixedly receives the auto focusing part (210) .
  12. The optical image stabilization system (10) according to claim 11, wherein the holder-side wire turning element (510c; 520c; 530c; 540c) is arranged on the movable frame (220) .
  13. The optical image stabilization system (10) according to any one of the preceding claims, wherein the optical image stabilization system (10) further comprises a leaf spring (700) interposed between the base (100) and the lens holder (200) , and wherein the lens holder (200) is supported and urged to a central position thereof by the leaf spring (700) .
  14. An optical image stabilization method to be implemented in the system (10) according to any one of the preceding claims, the method comprising a step of:
    operating the at least one actuator (410; 420; 430; 440) for moving the lens holder (200) relative to the base (100) in a direction needed for an image stabilization, by energizing the shape memory alloy wire (412; 422; 432; 442) of the at least one actuator (410; 420; 430; 440) .
  15. The optical image stabilization method according to claim 14, wherein the system (10) comprises four actuators (410; 420; 430; 440) arranged approximately 90 degrees apart from each other, and wherein in the operating step, two or three actuators of  the four actuators (410; 420; 430; 440) are operated simultaneously.
  16. A product (1) including a camera module (1a) , wherein the camera module (1a) comprises an optical image stabilization system (10) according to any one of claims 1 to 13.
  17. The product (1) according to claim 16, wherein the product (1) is a device, an apparatus, an equipment, a machine, a facility, a tool, or the like, which includes the camera module (1a) .
  18. The product (1) according to claim 17, wherein the product (1) is a mobile electronic device including the camera module (1a) .
PCT/CN2020/114969 2020-09-14 2020-09-14 Long stroke optical image stabilization system and method WO2022052083A1 (en)

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