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WO2021138766A1 - Optical image stabilizing system comprising shape memory alloy wires and methods of fabricating thereof - Google Patents

Optical image stabilizing system comprising shape memory alloy wires and methods of fabricating thereof Download PDF

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Publication number
WO2021138766A1
WO2021138766A1 PCT/CN2020/070451 CN2020070451W WO2021138766A1 WO 2021138766 A1 WO2021138766 A1 WO 2021138766A1 CN 2020070451 W CN2020070451 W CN 2020070451W WO 2021138766 A1 WO2021138766 A1 WO 2021138766A1
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WO
WIPO (PCT)
Prior art keywords
substrate
optics base
optical element
magnets
stabilizing system
Prior art date
Application number
PCT/CN2020/070451
Other languages
French (fr)
Inventor
Masaru Uno
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 CN202080093683.3A priority Critical patent/CN115004072B/en
Priority to PCT/CN2020/070451 priority patent/WO2021138766A1/en
Publication of WO2021138766A1 publication Critical patent/WO2021138766A1/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
    • G02B27/646—Imaging systems using optical elements for stabilisation of the lateral and angular position of the image compensating for small deviations, e.g. due to vibration or shake

Definitions

  • the present invention relates to an optical image stabilizing system comp rising shape memory alloy wires and a method of fabricating thereof.
  • an optical image stabilizing (OIS) system for compensating for a camera shake caused by a movement of the camera at a moment of taking an image has become essential.
  • a conventional optical image stabilizing system detects the movement of the camera and moves the optical element relative to the imaging element to relatively fix the optical image on the imaging element.
  • a voice coil motor is utilized for a movement of an optical element (for example, refer to Patent Documents 1 and 2) .
  • a voice coil motor is comprised of a coil disposed in a magnetic field caused by a permanent magnet. When an electrical current is applied to the coil, a force is generated to move the coil or the magnet.
  • a voice coil motor has advantages in which its configuration is simple and lightweight, and allows precise control.
  • Figure 6 shows a conventional optical image stabilizing system 600 comprising shape memory alloy wires.
  • the optical image stabilizing system 600 comprising:
  • an optical element 604 such as a lens separated from a surface of the substrate 602;
  • an optics base 606 supporting the optical element 604 and separated from the surface of the substrate 602;
  • one or more supporting members 608 disposed between the substrate 602 and the optics base 606 and supporting the optics base 606 such that the optical element 604 and the optics base 606 are moveable in a direction parallel to the surface of the substrate 602;
  • first to fourth tension poles 610A to 610D disposed on a periphery of the optics base 606;
  • first to fourth shape memory alloy (SMA) wires 612A to 612D such that one ends of the first to fourth SMA wires 612A to 612D are fixed on the substrate 602 and the other ends are fixed to the first to fourth tension poles 610A to 610D, respectively.
  • the first to fourth SMA wires 612A to 612D are configured to reduce their lengths when the wires are heated.
  • a method of operating the optical image stabilizing system is explained when the optical element 604 is moved upward in the figure as an example.
  • the first SMA wire 612A When the first SMA wire 612A is heated, the first SMA wire 612A reduces its length, and therefore a force is applied to the optics base 606 in a direction of an arrow 628A in the figure via the first tension pole 610A.
  • the force applied by the first SMA wire 612A is not directed to the center of the optical element 604, this force causes a moment rotating the optical element 604.
  • the second and fourth SMA wires 612B, 612D are heated up to a temperature lower than the temperature of the first SMA wire 612A to apply forces to the optics base 606 in directions of the arrows 628B, 628D via the second and fourth tension poles 610B, 610D, respectively.
  • the third SMA wire 612C is not heated.
  • the optical element 604 is moved upward in the figure while cancelling the rotation moment caused by the first SMA wire 612A.
  • Table 1 shows heating states of the first to fourth SMA wires 612A to 612D when the optical element 604 is moved in various directions. The movement directions in the table correspond to the directions shown in the figure.
  • the temperatures of the wires are indicated as “High” which means that the wire is fully heated, “Medium” which means that the wire is heated up to a temperature lower than “High” , and “Low” which means that the wire is not heated.
  • a conventional optical image stabilizing system comprising SMA wires causes a moment rotating an optical element because forces applied to an optics base by SMA wires are not directed to a center of the optical element. Therefore, a complicated temperature control is necessary to cancel the rotation moment as shown in Table 1, and thus it is difficult to obtain a desired movement of an optical element.
  • the present invention aims to overcome the above disadvantages of conventional optical image stabilizing system comprising SMA wires, and provides an optical image stabilizing system comprising SMA wires, which does not cause a moment rotating an optical element, and provides a method of fabricating thereof.
  • a first embodiment of the present invention provides an optical image stabilizing system comprising:
  • an optics base supporting the optical element and separated from the surface of the substrate
  • one or more supporting members disposed between the substrate and the optics base and supporting the optics base such that the optical element and the optics base are moveable in a direction parallel to the surface of the substrate;
  • first and second tension poles disposed on a periphery of the optics base and on a first straight line on which a center of the optical element is positioned, and wherein the center of the optical element is positioned between the first and second tension poles;
  • third and fourth tension poles disposed on the periphery of the optics base and on a second straight line on which the center of the optical element is positioned, wherein the second straight line intersects the first straight line at a predetermined angle, and wherein the center of the optical element is positioned between the third and fourth tension poles;
  • first to fourth shape memory alloy wires which are tensioned by fixing both ends on the substrate, respectively, wherein the first to fourth shape memory alloy wires are half-wrapped on the first to fourth tension poles, respectively,
  • first to fourth shape memory alloy wires are configured to apply forces to the optics base in a direction toward the center of the optical element via the first to fourth tension poles, respectively.
  • the first to fourth shape memory alloy wires are configured to reduce lengths by heat, respectively.
  • the heating is carried out by applying electrical currents through the first to fourth shape memory alloy wires, respectively.
  • the optical image stabilizing system further comprises:
  • one or more Hall elements provided on one surface of the substrate or the optics base;
  • one or more magnets provided on the other surface of the substrate or the optics base such that the magnets face the Hall elements, respectively,
  • the one or more Hall elements are configured to output signals related to a relative position of the optics base relative to the substrate.
  • the optical image stabilizing system further comprises:
  • one or more magnets provided on the other surface of the substrate or the optics base such that the magnets face the ferromagnetic members, respectively,
  • the one or more ferromagnetic members and the one or more magnets are configured to cause attractive forces between the optics base and the substrate, respectively.
  • the optical image stabilizing system further comprises:
  • one or more Hall elements provided on one surface of the substrate or the optics base;
  • one or more ferromagnetic members provided on the same surface of the substrate or the optics base as the surface on which the Hall elements are provided;
  • one or more magnets provided on the other surface of the substrate or the optics base such that the magnets face the Hall elements and the ferromagnetic members, respectively,
  • the one or more Hall elements are configured to output signals related to a relative position of the optics base relative to the substrate
  • the one or more ferromagnetic members and the one or more magnets are configured to cause attractive forces between the optics base and the substrate, respectively.
  • a second embodiment of the present invention provides a method of fabricating an optical image stabilizing system, comprising the steps of:
  • the optics base comprises:
  • first and second tension poles on a periphery of the optics base and on a first straight line on which a center of the optical element is positioned, wherein the center of the optical element is positioned between the first and second tension poles;
  • third and fourth tension poles disposed on the periphery of the optics base and on a second straight line on which the center of the optical element is positioned, wherein the second straight line intersects the first straight line at a predetermined angle, and wherein the center of the optical element is positioned between the third and fourth tension poles,
  • weights attaching weights at the other ends of the first to fourth shape memory alloy wires, respectively, and fixing the other ends of the first to fourth shape memory alloy wires on the substrate, wherein the weights have masses identical to each other, wherein the tensions are applied to the first to fourth shape memory alloy wires by gravity acting on the weights to half-wrap the first to fourth shape memory alloy wires on the first to fourth tension poles, respectively, and
  • the first to fourth shape memory alloy wires are configured to reduce their lengths by heating.
  • the heating is configured to be carried out by applying electric currents to the first to fourth shape memory alloy wires, respectively.
  • the method of fabricating an optical image stabilizing system further comprises:
  • the one or more Hall elements are configured to output signals related to a relative position of the optics base relative to the substrate.
  • the method of fabricating an optical image stabilizing system further comprises:
  • the one or more ferromagnetic members and the one or more magnets are configured to apply an attractive force between the optics base and the substrate, and
  • the one or more magnets hold the optics base at a predetermined position relative to the substrate.
  • the method of fabricating the optical image stabilizing system further comprises:
  • the one or more Hall elements are configured to output signals related to a relative position of the optics base relative to the substrate
  • the one or more ferromagnetic members and the one or more magnets are configured to apply an attractive force between the optics base and the substrate, and
  • the one or more magnets hold the optics base at a predetermined position relative to the substrate.
  • an optical image stabilizing system comprising SMA wires, which does not cause a moment rotating an optical element and the method of fabricating thereof can be provided.
  • Figure 1 shows a plan view of an optical image stabilizing system according to a first embodiment of the present invention.
  • Figure 2 shows a side view of the optical image stabilizing system shown in Figure 1.
  • Figure 3 shows an expanded perspective view of a part of the optical image stabilizing system shown in Figure 1.
  • Figure 4 shows a flow chart showing a method of fabricating the optical image stabilizing system according to the first embodiment of the present invention.
  • Figure 5 shows an expanded perspective view showing the step of fixing ends of SMA wires on a substrate of the method of fabricating the optical image stabilizing system shown in Figure 4.
  • Figure 6 shows a plan view of a conventional optical image stabilizing system.
  • Figure 1 shows a plan view of an optical image stabilizing system 100 using shape memory alloy (SMA) wires according to a first embodiment of the present invention.
  • Figure 2 shows a side view of the optical image stabilizing system 100 shown in Figure 1 and
  • Figure 3 shows an expanded view of a part of the optical image stabilizing system 100 shown in Figure 1.
  • SMA shape memory alloy
  • the optical image stabilizing system 100 comprises: a substrate 102; an optical element 104 separated from a surface of the substrate 102; an optics base 106 supporting the optical element 104 and separated from the surface of the substrate 102; and one or more supporting members 108 provided between the substrate 102 and the optics base 106 and supporting the optics base 106.
  • the substrate 102 is made from a conventional material such as glass, silicon, or metal, and a region of the substrate 102 facing the optical element 104 has a structure which allows light transmitting the optical element 104 to pass through.
  • a region of the substrate 102 facing the optical element 104 has a structure which allows light transmitting the optical element 104 to pass through.
  • the substrate 102 is made from glass, no opaque structures preventing light from passing through the substrate 102 are provided in this region.
  • the substrate 102 is made from an opaque material such as silicon or metal, a through hole may be provided in this region in order to allow light to pass through.
  • the optical element 104 may be a lens made from, for example, plastic or glass.
  • the optical element 104 preferably has a circular plane shape from a viewpoint of symmetry as discussed below. Other shapes may be employed. However, such shapes may complicate the design and control of the device.
  • the optical element 104 is supported by the optics base 106 such that the optical element 104 is separated from the surface of the substrate 102 at a predetermined distance.
  • the optics base 106 has a shape surrounding the optical element 104. However, the optics base 106 may have a shape which does not surround the entire optical element 104.
  • the optics base 106 may be made from a conventional material such as glass, silicon, or metal.
  • the optics base 106 is supported by one or more supporting members 108 such that the optics base 106 is separated from the surface of the substrate 102 at a predetermined distance.
  • the supporting members 108 are three balls in the example shown in Figure 1.
  • the optical element 104 and the optics base 106 may move in a direction parallel to the surface of the substrate 102 due to the rotation of the balls.
  • the supporting members 108 may be, for example, protrusions provided on the surface of the substrate 102 and in contact with the optics base 106 at apexes of the protrusions.
  • the apex may have a steep shape or a curved surface in order to ensure a very small contact area to decrease a frictional force between the optics base 106 and the apex.
  • the optics base 106 may smoothly slide on the apexes of the protrusions and move in a direction parallel to the surface of the substrate 102. If the supporting members 108 are the protrusions, there is an advantage in which the device is easily assembled because the supporting members 108 are fixed on the substrate 102. In an alternative example, the supporting members 108 may be spring structures which can suspend the optics base 106.
  • First and second tension poles 110A, 110B are provided at a periphery of the optics base 106 and on a first straight line 120 passing through a center 124 of the optical element 104 such that the center 124 of the optical element 104 is positioned between the first and second tension poles 110A, 110B.
  • the first and second tension poles 110A, 110B are preferably provided at the same distance from the center 124 of the optical element 104 from a viewpoint of symmetry.
  • Third and fourth tension poles 110C, 110D are provided at the periphery of the optics base 106 and on a second straight line 122 passing through the center 124 of the optical element 104 and intersecting with the first straight line 120 at a predetermined angle such that the center 124 of the optical element 104 is positioned between the third and fourth tension poles 110C, 110D.
  • the third and fourth tension poles 110C, 110D are preferably provided at the same distance from the center 124 of the optical element 104 from a viewpoint of symmetry.
  • the first straight line 120 is preferably orthogonal to the second straight line 122.
  • the first to fourth tension poles 110A to 110D may be provided to have other distances and angles. However, such an arrangement may complicate the design and control of the device.
  • One or more Hall elements 126 may be provided on the surface of the substrate 102.
  • One or more magnets 128 may be provided on the surface of the optics base 106 such that the magnets 128 face the Hall elements 126, respectively.
  • the Hall element 126 may detect a change of a relative position of the magnet 128 relative to the Hall element 126 caused by the movement of the optics base 106 and output signals indicating the relative position of the optics base 106 and the optical element 104.
  • One or more ferromagnetic members may be provided on the surface of the substrate 102.
  • the magnets may be provided on the surface of the optics base 106 such that the magnets face the ferromagnetic members, respectively.
  • the magnet and the ferromagnetic member can cause an attractive force therebetween, and thus hold the optics base 106 at a predetermined position. Therefore, for example, when the device is assembled, the optics base 106 may be positioned at a correct position relative to the substrate 102.
  • the attractive force may work as a restoring force to quickly move the optics base 106 from the displaced position to the predetermined position.
  • the Hall element 126 and the ferromagnetic member may face different magnets, respectively, or the Hall element 126 and the ferromagnetic member may face one common magnet.
  • Hall elements 126 and the ferromagnetic members are provided on the substrate 102 and the magnets 128 are provided on the optics base 106, these components may be provided oppositely.
  • the Hall elements 126 are provided on the substrate 102, there is an advantage in which extraction of signals from the Hall elements 126 is easy.
  • the optical image stabilizing system 100 comprises first to fourth shape memory alloy (SMA) wires 112A to 112D of which both ends are fixed on power supply terminals 114 provided on the surface of the substrate 102, and which are half-wrapped on the first to fourth tension poles 110A to 110D, respectively, while tensions are applied on the wires.
  • Figure 3 is the expanded figure of the first tension pole 110A and the first SMA wire 112A of the optical image stabilizing system 100.
  • the SMA wires may be, for example, made of various known materials such as nickel-titanium based alloy including nickel and titanium, and ferrite based shape memory alloy including ferrite, manganese, and silicon.
  • the SMA wire When the SMA wire is heated, for example, up to the range between 100 °C and 110 °C, the length of the SMA wire is reduced about 3%from its original length, and when the SMA wire is cooled to the room temperature, the SMA wire recovers the original length.
  • the Young modulus is relatively small at the room temperature, and the SMA wire may be elastic.
  • the power supply terminals 114 are configured to apply electric current to the first to fourth SMA wires 112A to 112D. Therefore, the power supply terminals 114 may be insulated from the substrate 102.
  • Figure 3 shows that the first tension pole 110A comprises a groove 126A.
  • the first SMA wire 112A is half-wrapped on the first tension pole 110A at the groove 126A.
  • the groove 126A holds the first SMA wire 112A at a predetermined position on the first tension pole 110A.
  • the first tension pole 110A may comprise a through hole through which the first SMA wire 112A passes. In this case, since the first SMA wire 112A has to be passed through the through hole, the assembly process becomes complicated. However, the through hole ensure to hold the first SMA wire 112A and prevents the first SMA wire 112A from being removed from the first tension pole 110A during the operation.
  • the first SMA wire 112A applies a force to the optics base 106 via the first tension pole 110A in a direction of the arrow 128A in the figure which is directed to the center 124 of the optical element 104.
  • This force causes a displacement of the optics base 106 in the direction of the arrow 128A.
  • the first SMA wire 112A is preferably arranged in line-symmetric with respect to the first straight line 120.
  • the first SMA wire 112A is preferably half-wrapped on the first tension pole 110A at the center of the first SMA wire 112A.
  • the power supply terminals 114, to which the both ends of the first SMA wire 112A is connected, are preferably arranged in line-symmetric with respect to the first straight line 120. The same applies to the second to fourth SMA wires 112B to 112D.
  • Table 2 shows the heating/non-heating states of the first to fourth SMA wires 112A to 112D when the optical element 104 is moved to each direction in the figure.
  • the movement directions correspond to the directions in the figure, and the temperatures of the wires are indicated as “High” which means the wire is fully heated, “Medium” which means that the wire is heated up to a temperature lower than “High” , and “Low” which means that the wire is not heated.
  • the degree of heating can be selected by adjusting the amount of the electric current applied to the SMA wire.
  • the resultant force is in the upward direction in the figure (+y direction) .
  • the temperatures of the SMA wires are controlled as indicated in Table 2 to move the optical element 104.
  • an electric current is applied to the first SMA wire 112A to heat the first SMA wire 112A to the high temperature state (for example, 110 °C) .
  • An electric current is not applied to the second SMA wire 112B opposing the first SMA wire 112A to maintain the second SMA wire 112B in the low temperature state (for example, the room temperature) .
  • the force applied to the optics base 106 is in the direction of the arrow 128A, the optical element 104 moves in the upper-right direction.
  • the optical element 104 can displace in a desired direction without deviating from the direction of the arrow 128A.
  • the temperatures of the SMA wires are also controlled to move in other directions, for example, lower-right (an intermediate direction between –y direction and +x direction) , upper-left (an intermediate direction between +y direction and –x direction) , and lower-left (an intermediate direction between –y direction and –x direction) directions as shown in Table 2.
  • the optical element can be moved in a desired direction by controlling the temperatures of the SMA wires as shown in Table 2. Since the tension poles and the SMA wires are arranged with high symmetry with respect to the center of the optical element, the forces applied to the optics base by the SMA wires direct to the center of the optical element. Therefore, no rotation moment, which causes the rotation of the optics base, is applied to the optics base. Eliminating the rotation moment simplifies the process of controlling the temperatures of the SMA wires of the first embodiment of the optical image stabilizing system shown in Table 2 compared to the method of controlling the temperatures of the SMA wires of the conventional optical image stabilizing system shown in Figure 6 and Table 1.
  • the first embodiment of the optical image stabilizing system has further advantages. Since the first and second SMA wires 112A, 112B are symmetrically arranged with respect to the center 124 of the optical element 104, the forces applied to the optics base 106 by the first and second SMA wires 112A, 112B are opposite to each other. Therefore, the differential drive method can be utilized to displace the optics base 106. When the force applied to the optics base 106 by the first SMA wire 112A is larger than the force applied to the optics base 106 by the second SMA wire 112B, the optics base 106 moves in the upper right direction in the figure.
  • the differential drive method can improve the response speed.
  • the optical image stabilizing system according to the embodiment of the present invention since the optical image stabilizing system according to the embodiment of the present invention has the SMA wires of which both ends are connected to the power supply terminals 114, electrical current can be easily applied to the SMA wires.
  • one end of the SMA wire is connected to the power supply terminal on the substrate, while the other end is connected to the optics base. Therefore, a contact point, which can supply an electrical current, has to be provided to the optics base. Therefore, the design of the optics base and the assembly process of the optical image stabilizing system may become more complicated.
  • the range of the length reduction of the SMA wire is preferably up to about 3%considering the maintenance of the shape memory function, the stability of the crystal structure, and the durability. Since the SMA wires of the optical image stabilizing system of the present application are longer than the SMA wires of the conventional optical image stabilizing system shown in Figure 6, the ranges of the length reduction of the SMA wires, i.e., the displacement of the optical element 104 can be increased compared to that of the conventional optical image stabilizing system. For example, regarding the optical image stabilizing systems having the same area, the SMA wire of the present invention shown in Figure 1 is twice as long as the conventional SMA wire shown in Figure 6.
  • the optical image stabilizing system of the present invention can realize a larger displacement of the optical element compared to the conventional optical image stabilizing system, and therefore address a larger camera shake.
  • the optical image stabilizing system according to the embodiment of the present invention has the SMA wire of which both ends are connected to the power supply terminals 114, the SMA wire can apply forces in two directions to one tension pole.
  • the force applied to the optics base 106 via the tension pole is the resultant force of the forces in the two directions. For example, if a force f is applied to the tension pole by reducing the length of the SMA wire, the component of the force in the direction toward the center of the optical element of the conventional optical image stabilizing system shown in Figure 6 is f/ ⁇ (2) .
  • the optical image stabilizing system according to the embodiment of the present application can move the optical element with a force larger than the conventional optical image stabilizing system and therefore, improve the response speed and carry out a displacement of a larger optical element.
  • the number of the SMA wires is preferably even and the SMA wires are preferably arranged in symmetry with respect to the center of the optical element.
  • the number of the SMA wires may be other than four, for example, the number may be three or five or more. However, considering the above discussions, the number of the SMA wires is preferably four as shown in Figure 1.
  • Figure 4 shows a flow chart of a method 400 of fabricating the optical image stabilizing system according to the embodiment of the present application shown in Figure 1.
  • the substrate 102 is provided.
  • the substrate 102 is made from a conventional material such as glass, silicon, and metal.
  • a region to face the optical element 104 has a structure which allows light transmitting the optical element 104 to pass through.
  • the substrate 102 is made from glass, no opaque structures preventing light from passing through the substrate 102 are provided in this region.
  • the substrate 102 is made from an opaque material such as silicon or metal, a through hole may be provided in this region in order to allow light to pass through.
  • the optical element 104 and the optics base 106 configured to support the optical element 104 are provided.
  • the optical element 104 may be a lens made from, for example, plastic or glass.
  • the optical element 104 is supported by the optics base 106.
  • the optics base 106 may be made from a conventional material such as glass, silicon, or metal.
  • the first and second tension poles 110A, 110B are formed at the periphery of the optics base 106 and on the first straight line 120 passing through the center 124 of the optical element 104 such that the center 124 of the optical element 104 is positioned between the first and second tension poles 110A, 110B.
  • the third and fourth tension poles 110C, 110D are provided at the periphery of the optics base 106 and on the second straight line 122 passing through the center 124 of the optical element 104 and intersecting with the first straight line 120 at a predetermined angle, preferably being orthogonal to the first straight line, such that the center 124 of the optical element 104 is positioned between the third and fourth tension poles 110C, 110D.
  • the one or more support members 108 supporting the optics base 106 are provided on the surface of the substrate 102.
  • the support members 108 may be, for example, three balls.
  • the optical element 104 and the optics base 106 may move in a direction parallel to the surface of the substrate 102 due to the rotation of the balls.
  • the supporting members 108 may be, for example, protrusions provided on the surface of the substrate 102 and in contact with the optics base 106 at the apexes of the protrusions, and providing smooth sliding movement of the optics base 106. If the supporting members 108 are the protrusions, there is an advantage in which the device is easily assembled because the supporting members 108 are fixed on the substrate 102.
  • the supporting members 108 may be spring structures which can suspend the optics base 106.
  • the optics base 106 is supported by the supporting members 108 such that the optical element 104 and the optics base 106 are separated from the surface of the substrate 102 and moveable in a direction parallel to the surface of the substrate 102.
  • one or more ferromagnetic members may be provided on either one of the substrate 102 or the optics base 106, and one or more magnets may be provided on the other of the substrate 102 or the optics base 106 such that the magnets face the ferromagnetic members, respectively.
  • the ferromagnetic members and the magnets cause an attractive force between the optics base 106 and the substrate 102, which allows the optics base 106 to be easily held at and aligned to a predetermined position relative to the substrate 102.
  • the supporting members 108 are the balls, it is advantageous to hold the optics base 106 by the magnets because the supporting members108 are not fixed to both of the substrate 102 and the optics base 106.
  • step 410 one ends of the first to fourth SMA wires 112A to 112D are fixed to the power supply terminals 114 on the substrate 102, respectively.
  • the first to fourth SMA wires 112A to 112D are half-wrapped on the first to fourth tension poles 110A to 110D and are inserted in through holes 422 provided on the substrate 102, respectively.
  • Weights 424 having masses identical to each other are attached at the other ends of the first to fourth SMA wires 112A to 112D. Due to the gravity applied to the weights 424, identical tensions are applied to the first to fourth SMA wires 112A to 112D.
  • the power supply terminals 114 are inserted to the through holes 422 to fix the first to fourth SMA wires 112A to 112D.
  • Figure 5 shows an expanded perspective view when the step 412 is carried out for the first SMA wire 112A. Since electrical currents are applied to the first to fourth SMA wires 112A to 112D via the power supply terminals 114 during the operation of the optical image stabilizing system 100, at least surfaces of the through holes 422 are preferably covered with an insulation material.
  • the center of the optical element 104 can be aligned to the origin of the optics. If the same amounts of electrical currents are applied to the first to fourth SMA wires 112A to 112D to heat the SMA wires, respectively, the amounts of length reductions of the first to fourth SMA wires 112A to 112D and the forces applied to the optics base 106 are identical to each other. Therefore, the control of the displacement of the optical element 104 becomes significantly easy.
  • step 414 the weights 424 and residual portions of the first to fourth SMA wires 112A to 112D are removed to obtain the optical image stabilizing system 100.
  • 112A to 112D First to fourth shape memory alloy (SMA) wires

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Abstract

An optical image stabilizing system (100) comprises: a substrate (102); an optical element (104); an optics base (106); one or more supporting members (108); first and second tension poles (110A,110B) disposed on a periphery of the optics base (106) and on a first straight line on which a center of the optical element (104) is positioned; third and fourth tension poles (110C,110D) disposed on the periphery of the optics base (106) and on a second straight line on which the center of the optical element (104) is positioned; and first to fourth shape memory alloy wires (112A to 112D) which are tensioned by fixing both ends on the substrate (102), respectively, wherein the first to fourth shape memory alloy wires (112A to 112D) are half-wrapped on the first to fourth tension poles, respectively, wherein the first to fourth shape memory alloy wires (112A to 112D) are configured to apply forces to the optics base (106) in a direction toward the center of the optical element (104) via the first to fourth tension poles, respectively.

Description

Optical Image Stabilizing System Comprising Shape Memory Alloy Wires and Methods of Fabricating Thereof Field of the Invention
The present invention relates to an optical image stabilizing system comp rising shape memory alloy wires and a method of fabricating thereof.
Background
As image quality of cameras mounted on mobile devices such as a smartphone and a tablet computer improve, various optical compensations are becoming necessary. In particular, an optical image stabilizing (OIS) system for compensating for a camera shake caused by a movement of the camera at a moment of taking an image has become essential.
When a camera including an imaging element is moved, an optical image projected on the imaging element by optical elements such as a lens is relatively moved on the imaging element, and results in a camera shake. Therefore, a conventional optical image stabilizing system detects the movement of the camera and moves the optical element relative to the imaging element to relatively fix the optical image on the imaging element.
For example, a voice coil motor is utilized for a movement of an optical element (for example, refer to Patent Documents 1 and 2) . A voice coil motor is comprised of a coil disposed in a magnetic field caused by a permanent magnet. When an electrical current is applied to the coil, a force is generated to move the coil or the magnet. A voice coil motor has advantages in which its configuration is simple and lightweight, and allows precise control.
Methods utilizing shape memory alloy wires have been proposed in order to provide a movement of an optical element without using a voice coil motor (for example, Patent Documents 3 to 5) . Figure 6 shows a conventional optical image stabilizing system 600 comprising shape memory alloy wires. The optical image stabilizing system 600 comprising:
a substrate 602;
an optical element 604 such as a lens separated from a surface of the substrate 602;
an optics base 606 supporting the optical element 604 and separated from the  surface of the substrate 602;
one or more supporting members 608 disposed between the substrate 602 and the optics base 606 and supporting the optics base 606 such that the optical element 604 and the optics base 606 are moveable in a direction parallel to the surface of the substrate 602;
first to fourth tension poles 610A to 610D disposed on a periphery of the optics base 606; and
first to fourth shape memory alloy (SMA) wires 612A to 612D such that one ends of the first to fourth SMA wires 612A to 612D are fixed on the substrate 602 and the other ends are fixed to the first to fourth tension poles 610A to 610D, respectively. The first to fourth SMA wires 612A to 612D are configured to reduce their lengths when the wires are heated.
A method of operating the optical image stabilizing system is explained when the optical element 604 is moved upward in the figure as an example. When the first SMA wire 612A is heated, the first SMA wire 612A reduces its length, and therefore a force is applied to the optics base 606 in a direction of an arrow 628A in the figure via the first tension pole 610A. However, since the force applied by the first SMA wire 612A is not directed to the center of the optical element 604, this force causes a moment rotating the optical element 604. In order to cancel the moment, the second and  fourth SMA wires  612B, 612D are heated up to a temperature lower than the temperature of the first SMA wire 612A to apply forces to the optics base 606 in directions of the  arrows  628B, 628D via the second and  fourth tension poles  610B, 610D, respectively. The third SMA wire 612C is not heated. In this case, the optical element 604 is moved upward in the figure while cancelling the rotation moment caused by the first SMA wire 612A. Table 1 shows heating states of the first to fourth SMA wires 612A to 612D when the optical element 604 is moved in various directions. The movement directions in the table correspond to the directions shown in the figure. The temperatures of the wires are indicated as “High” which means that the wire is fully heated, “Medium” which means that the wire is heated up to a temperature lower than “High” , and “Low” which means that the wire is not heated.
Figure PCTCN2020070451-appb-000001
Figure PCTCN2020070451-appb-000002
Table 1: Operation of a conventional optical image stabilizing system comprising SMA wires
A conventional optical image stabilizing system comprising SMA wires causes a moment rotating an optical element because forces applied to an optics base by SMA wires are not directed to a center of the optical element. Therefore, a complicated temperature control is necessary to cancel the rotation moment as shown in Table 1, and thus it is difficult to obtain a desired movement of an optical element.
Prior Art Publication
1. Japanese Unexamined Patent Application, First Publication No. 2011-065140
2. Japanese Unexamined Patent Application, First Publication No. 2014-206590
3. PCT International Publication No. WO 2014/076463
4. United States Patent No. US 6,981,374
5. United States Patent Application, Publication No. US 2010/0060776
Summary of Invention
Problem to be Solved by Invention
The present invention aims to overcome the above disadvantages of conventional optical image stabilizing system comprising SMA wires, and provides an optical image stabilizing system comprising SMA wires, which does not cause a moment rotating an optical element, and provides a method of fabricating thereof.
Means for Solving Problem
For solving the above problem, a first embodiment of the present invention provides an optical image stabilizing system comprising:
a substrate;
an optical element separated from a surface of the substrate;
an optics base supporting the optical element and separated from the surface of the substrate;
one or more supporting members disposed between the substrate and the optics base and supporting the optics base such that the optical element and the optics base are moveable in a direction parallel to the surface of the substrate;
first and second tension poles disposed on a periphery of the optics base and on a first straight line on which a center of the optical element is positioned, and wherein the center of the optical element is positioned between the first and second tension poles;
third and fourth tension poles disposed on the periphery of the optics base and on a second straight line on which the center of the optical element is positioned, wherein the second straight line intersects the first straight line at a predetermined angle, and wherein the center of the optical element is positioned between the third and fourth tension poles; and
first to fourth shape memory alloy wires which are tensioned by fixing both ends on the substrate, respectively, wherein the first to fourth shape memory alloy wires are half-wrapped on the first to fourth tension poles, respectively,
wherein the first to fourth shape memory alloy wires are configured to apply forces to the optics base in a direction toward the center of the optical element via the first to fourth tension poles, respectively.
According to one aspect of the first embodiment of the present invention, the first to fourth shape memory alloy wires are configured to reduce lengths by heat, respectively.
According to one aspect of the first embodiment of the present invention, the heating is carried out by applying electrical currents through the first to fourth shape memory alloy wires, respectively.
According to one aspect of the first embodiment of the present invention, the optical image stabilizing system further comprises:
one or more Hall elements provided on one surface of the substrate or the optics base; and
one or more magnets provided on the other surface of the substrate or the optics base such that the magnets face the Hall elements, respectively,
wherein the one or more Hall elements are configured to output signals related to a relative position of the optics base relative to the substrate.
According to one aspect of the first embodiment of the present application, the  optical image stabilizing system further comprises:
one or more ferromagnetic members provided on one surface of the substrate or the optics base; and
one or more magnets provided on the other surface of the substrate or the optics base such that the magnets face the ferromagnetic members, respectively,
wherein the one or more ferromagnetic members and the one or more magnets are configured to cause attractive forces between the optics base and the substrate, respectively.
According to one aspect of the first embodiment of the present application, the optical image stabilizing system further comprises:
one or more Hall elements provided on one surface of the substrate or the optics base;
one or more ferromagnetic members provided on the same surface of the substrate or the optics base as the surface on which the Hall elements are provided; and
one or more magnets provided on the other surface of the substrate or the optics base such that the magnets face the Hall elements and the ferromagnetic members, respectively,
wherein the one or more Hall elements are configured to output signals related to a relative position of the optics base relative to the substrate, and
wherein the one or more ferromagnetic members and the one or more magnets are configured to cause attractive forces between the optics base and the substrate, respectively.
A second embodiment of the present invention provides a method of fabricating an optical image stabilizing system, comprising the steps of:
providing a substrate;
providing an optical element and an optics base supporting the optical element, wherein the optics base comprises:
first and second tension poles on a periphery of the optics base and on a first straight line on which a center of the optical element is positioned, wherein the center of the optical element is positioned between the first and second tension poles; and
third and fourth tension poles disposed on the periphery of the optics base and on a second straight line on which the center of the optical element is positioned, wherein the second straight line intersects the first straight line at a predetermined angle, and wherein the center of the optical element is positioned between the third and fourth tension poles,
providing one or more supporting members on a surface of the substrate, the one or more supporting members supporting the optics base;
supporting the optics base by the one or more supporting members such that the optical element and the optics base are separated from the surface of the substrate and are moveable in a direction parallel to the surface of the substrate;
fixing one ends of first to fourth shape memory alloy wires on the substrate, respectively,
attaching weights at the other ends of the first to fourth shape memory alloy wires, respectively, and fixing the other ends of the first to fourth shape memory alloy wires on the substrate, wherein the weights have masses identical to each other, wherein the tensions are applied to the first to fourth shape memory alloy wires by gravity acting on the weights to half-wrap the first to fourth shape memory alloy wires on the first to fourth tension poles, respectively, and
removing the weights from the first to fourth shape memory alloy wires.
According to one aspect of the second embodiment of the present invention, the first to fourth shape memory alloy wires are configured to reduce their lengths by heating.
According to one aspect of the second embodiment of the present invention, the heating is configured to be carried out by applying electric currents to the first to fourth shape memory alloy wires, respectively.
According to one aspect of the second embodiment of the present invention, the method of fabricating an optical image stabilizing system further comprises:
providing one or more Hall elements on one surface of the substrate or the optics base; and
providing one or more magnets on the other surface of the substrate or the optics base such that the magnets face the Hall elements, respectively,
wherein the one or more Hall elements are configured to output signals related to a relative position of the optics base relative to the substrate.
According to one aspect of the second embodiment of the present invention, the method of fabricating an optical image stabilizing system further comprises:
providing one or more ferromagnetic members on one surface of the substrate or the optics base; and
providing one or more magnets on the other surface of the substrate or the optics base such that the magnets face the ferromagnetic members, respectively,
wherein the one or more ferromagnetic members and the one or more magnets are configured to apply an attractive force between the optics base and the substrate, and
wherein in the step of supporting the optics base by the one or more supporting members, the one or more magnets hold the optics base at a predetermined position relative to the substrate.
According to one aspect of the second embodiment of the present invention, the method of fabricating the optical image stabilizing system further comprises:
providing one or more Hall elements on one surface of the substrate or the optics base;
providing one or more ferromagnetic members on the same surface of the substrate or the optics base as the surface on which the Hall elements were provided; and
providing one or more magnets on the other surface of the substrate or the optics base such that the magnets face the Hall elements and the ferromagnetic members, respectively,
wherein the one or more Hall elements are configured to output signals related to a relative position of the optics base relative to the substrate,
wherein the one or more ferromagnetic members and the one or more magnets are configured to apply an attractive force between the optics base and the substrate, and
wherein in the step of supporting the optics base by the one or more supporting members, the one or more magnets hold the optics base at a predetermined position relative to the substrate.
Effect of the Invention
According to the embodiments of the present invention, an optical image stabilizing system comprising SMA wires, which does not cause a moment rotating an optical element and the method of fabricating thereof can be provided.
Brief Explanation of Figures
Figure 1 shows a plan view of an optical image stabilizing system according to a first embodiment of the present invention.
Figure 2 shows a side view of the optical image stabilizing system shown in Figure 1.
Figure 3 shows an expanded perspective view of a part of the optical image stabilizing system shown in Figure 1.
Figure 4 shows a flow chart showing a method of fabricating the optical image  stabilizing system according to the first embodiment of the present invention.
Figure 5 shows an expanded perspective view showing the step of fixing ends of SMA wires on a substrate of the method of fabricating the optical image stabilizing system shown in Figure 4.
Figure 6 shows a plan view of a conventional optical image stabilizing system.
Embodiments
Figure 1 shows a plan view of an optical image stabilizing system 100 using shape memory alloy (SMA) wires according to a first embodiment of the present invention. Figure 2 shows a side view of the optical image stabilizing system 100 shown in Figure 1 and Figure 3 shows an expanded view of a part of the optical image stabilizing system 100 shown in Figure 1.
The optical image stabilizing system 100 comprises: a substrate 102; an optical element 104 separated from a surface of the substrate 102; an optics base 106 supporting the optical element 104 and separated from the surface of the substrate 102; and one or more supporting members 108 provided between the substrate 102 and the optics base 106 and supporting the optics base 106.
The substrate 102 is made from a conventional material such as glass, silicon, or metal, and a region of the substrate 102 facing the optical element 104 has a structure which allows light transmitting the optical element 104 to pass through. For example, if the substrate 102 is made from glass, no opaque structures preventing light from passing through the substrate 102 are provided in this region. If the substrate 102 is made from an opaque material such as silicon or metal, a through hole may be provided in this region in order to allow light to pass through.
The optical element 104 may be a lens made from, for example, plastic or glass. The optical element 104 preferably has a circular plane shape from a viewpoint of symmetry as discussed below. Other shapes may be employed. However, such shapes may complicate the design and control of the device. The optical element 104 is supported by the optics base 106 such that the optical element 104 is separated from the surface of the substrate 102 at a predetermined distance. The optics base 106 has a shape surrounding the optical element 104. However, the optics base 106 may have a shape which does not surround the entire optical element 104. The optics base 106 may be made from a conventional material such as glass, silicon, or metal.
The optics base 106 is supported by one or more supporting members 108 such that the optics base 106 is separated from the surface of the substrate 102 at a  predetermined distance. The supporting members 108 are three balls in the example shown in Figure 1. The optical element 104 and the optics base 106 may move in a direction parallel to the surface of the substrate 102 due to the rotation of the balls. Alternatively, the supporting members 108 may be, for example, protrusions provided on the surface of the substrate 102 and in contact with the optics base 106 at apexes of the protrusions. The apex may have a steep shape or a curved surface in order to ensure a very small contact area to decrease a frictional force between the optics base 106 and the apex. In this case, the optics base 106 may smoothly slide on the apexes of the protrusions and move in a direction parallel to the surface of the substrate 102. If the supporting members 108 are the protrusions, there is an advantage in which the device is easily assembled because the supporting members 108 are fixed on the substrate 102. In an alternative example, the supporting members 108 may be spring structures which can suspend the optics base 106.
First and  second tension poles  110A, 110B are provided at a periphery of the optics base 106 and on a first straight line 120 passing through a center 124 of the optical element 104 such that the center 124 of the optical element 104 is positioned between the first and  second tension poles  110A, 110B. The first and  second tension poles  110A, 110B are preferably provided at the same distance from the center 124 of the optical element 104 from a viewpoint of symmetry. Third and fourth tension poles 110C, 110D are provided at the periphery of the optics base 106 and on a second straight line 122 passing through the center 124 of the optical element 104 and intersecting with the first straight line 120 at a predetermined angle such that the center 124 of the optical element 104 is positioned between the third and fourth tension poles 110C, 110D. The third and fourth tension poles 110C, 110D are preferably provided at the same distance from the center 124 of the optical element 104 from a viewpoint of symmetry. The first straight line 120 is preferably orthogonal to the second straight line 122. The first to fourth tension poles 110A to 110D may be provided to have other distances and angles. However, such an arrangement may complicate the design and control of the device.
One or more Hall elements 126 may be provided on the surface of the substrate 102. One or more magnets 128 may be provided on the surface of the optics base 106 such that the magnets 128 face the Hall elements 126, respectively. The Hall element 126 may detect a change of a relative position of the magnet 128 relative to the Hall element 126 caused by the movement of the optics base 106 and output signals indicating the relative position of the optics base 106 and the optical element 104.
One or more ferromagnetic members may be provided on the surface of the  substrate 102. The magnets may be provided on the surface of the optics base 106 such that the magnets face the ferromagnetic members, respectively. The magnet and the ferromagnetic member can cause an attractive force therebetween, and thus hold the optics base 106 at a predetermined position. Therefore, for example, when the device is assembled, the optics base 106 may be positioned at a correct position relative to the substrate 102. Furthermore, the attractive force may work as a restoring force to quickly move the optics base 106 from the displaced position to the predetermined position.
The Hall element 126 and the ferromagnetic member may face different magnets, respectively, or the Hall element 126 and the ferromagnetic member may face one common magnet.
Although the explanation was made about the example in which the Hall elements 126 and the ferromagnetic members are provided on the substrate 102 and the magnets 128 are provided on the optics base 106, these components may be provided oppositely. When the Hall elements 126 are provided on the substrate 102, there is an advantage in which extraction of signals from the Hall elements 126 is easy.
Furthermore, the optical image stabilizing system 100 comprises first to fourth shape memory alloy (SMA) wires 112A to 112D of which both ends are fixed on power supply terminals 114 provided on the surface of the substrate 102, and which are half-wrapped on the first to fourth tension poles 110A to 110D, respectively, while tensions are applied on the wires. Figure 3 is the expanded figure of the first tension pole 110A and the first SMA wire 112A of the optical image stabilizing system 100.
The SMA wires may be, for example, made of various known materials such as nickel-titanium based alloy including nickel and titanium, and ferrite based shape memory alloy including ferrite, manganese, and silicon. When the SMA wire is heated, for example, up to the range between 100 ℃ and 110 ℃, the length of the SMA wire is reduced about 3%from its original length, and when the SMA wire is cooled to the room temperature, the SMA wire recovers the original length. The Young modulus is relatively small at the room temperature, and the SMA wire may be elastic. The power supply terminals 114 are configured to apply electric current to the first to fourth SMA wires 112A to 112D. Therefore, the power supply terminals 114 may be insulated from the substrate 102.
Figure 3 shows that the first tension pole 110A comprises a groove 126A. The first SMA wire 112A is half-wrapped on the first tension pole 110A at the groove 126A. The groove 126A holds the first SMA wire 112A at a predetermined position on the first tension pole 110A. Instead of the groove, the first tension pole 110A may  comprise a through hole through which the first SMA wire 112A passes. In this case, since the first SMA wire 112A has to be passed through the through hole, the assembly process becomes complicated. However, the through hole ensure to hold the first SMA wire 112A and prevents the first SMA wire 112A from being removed from the first tension pole 110A during the operation.
Again referring to Figures 1 and 2, the method of operating the optical image stabilizing system 100 is explained.
When an electric current is applied to the first SMA wire 112A via the power supply terminals 114 and the first SMA wire 112A is heated, the length of the first SMA wire 112A is reduced. Thus, the first SMA wire 112A applies a force to the optics base 106 via the first tension pole 110A in a direction of the arrow 128A in the figure which is directed to the center 124 of the optical element 104. This force causes a displacement of the optics base 106 in the direction of the arrow 128A. In order not to apply a rotation moment to the optics base 106, it is preferable that the direction of the force applied to the optics base 106 by the first SMA wire 112A correctly directs to the center 124 of the optical element 104. Therefore, the first SMA wire 112A is preferably arranged in line-symmetric with respect to the first straight line 120. In other words, the first SMA wire 112A is preferably half-wrapped on the first tension pole 110A at the center of the first SMA wire 112A. Furthermore, the power supply terminals 114, to which the both ends of the first SMA wire 112A is connected, are preferably arranged in line-symmetric with respect to the first straight line 120. The same applies to the second to fourth SMA wires 112B to 112D.
Table 2 shows the heating/non-heating states of the first to fourth SMA wires 112A to 112D when the optical element 104 is moved to each direction in the figure. In this table, the movement directions correspond to the directions in the figure, and the temperatures of the wires are indicated as “High” which means the wire is fully heated, “Medium” which means that the wire is heated up to a temperature lower than “High” , and “Low” which means that the wire is not heated. The degree of heating can be selected by adjusting the amount of the electric current applied to the SMA wire.
When the optical element 104 is moved in a upward direction in the figure (+y direction) , electric currents are applied to the first and  fourth SMA wires  112A, 112D to heat the first and  fourth SMA wires  112A, 112D up to the high temperature state (for example, 110 ℃) . Since an electric current is not applied to the second and  third SMA wires  112B, 112C to maintain the second and third SMA wires at a low temperature state (for example, a room temperature) . In this case, since the forces applied to the optics base 106 by the first and  fourth SMA wires  112A, 112D are in the directions  indicated by the  arrows  128A, 128D, respectively, the resultant force is in the upward direction in the figure (+y direction) . Regarding downward (-y direction) , right (+x direction) , and left (-x) directions, the temperatures of the SMA wires are controlled as indicated in Table 2 to move the optical element 104.
In case that the optical element 104 is moved in, for example, an upper-right direction (an intermediate direction between +y and +x directions) , an electric current is applied to the first SMA wire 112A to heat the first SMA wire 112A to the high temperature state (for example, 110 ℃) . An electric current is not applied to the second SMA wire 112B opposing the first SMA wire 112A to maintain the second SMA wire 112B in the low temperature state (for example, the room temperature) . In this case, since the force applied to the optics base 106 is in the direction of the arrow 128A, the optical element 104 moves in the upper-right direction. However, in order to more precisely control the movement direction, electric currents are applied to the third and  fourth SMA wires  112C, 112D to heat them in the medium temperature state (for example, a temperature between the room temperature and 110 ℃) as shown in Table 2, the lengths of the third and  fourth SMA wires  112C, 112D are reduced to apply forces to the optics base 106 in the directions of  arrows  128C, 128D via the third and fourth tension poles 110C, 110D, respectively. Since the third and fourth tension poles 110C, 110D are preferably arranged in symmetry on the second straight line 122 such that the center 124 of the optical element 104 is arranged between the third and fourth tension poles 110C, 110D, these two forces have directions opposite to each other and therefore cancel each other. Therefore, the optical element 104 can displace in a desired direction without deviating from the direction of the arrow 128A. The temperatures of the SMA wires are also controlled to move in other directions, for example, lower-right (an intermediate direction between –y direction and +x direction) , upper-left (an intermediate direction between +y direction and –x direction) , and lower-left (an intermediate direction between –y direction and –x direction) directions as shown in Table 2.
Figure PCTCN2020070451-appb-000003
Figure PCTCN2020070451-appb-000004
Table 2: Operation of the optical image stabilizing system of the first embodiment of the present invention
According to the first embodiment of the optical image stabilizing system, the optical element can be moved in a desired direction by controlling the temperatures of the SMA wires as shown in Table 2. Since the tension poles and the SMA wires are arranged with high symmetry with respect to the center of the optical element, the forces applied to the optics base by the SMA wires direct to the center of the optical element. Therefore, no rotation moment, which causes the rotation of the optics base, is applied to the optics base. Eliminating the rotation moment simplifies the process of controlling the temperatures of the SMA wires of the first embodiment of the optical image stabilizing system shown in Table 2 compared to the method of controlling the temperatures of the SMA wires of the conventional optical image stabilizing system shown in Figure 6 and Table 1.
The first embodiment of the optical image stabilizing system has further advantages. Since the first and  second SMA wires  112A, 112B are symmetrically arranged with respect to the center 124 of the optical element 104, the forces applied to the optics base 106 by the first and  second SMA wires  112A, 112B are opposite to each other. Therefore, the differential drive method can be utilized to displace the optics base 106. When the force applied to the optics base 106 by the first SMA wire 112A is larger than the force applied to the optics base 106 by the second SMA wire 112B, the optics base 106 moves in the upper right direction in the figure. However, when the first SMA wire 112A stops applying the force to the optics base 106, the optics base 106 is pushed back to the original position by the force applied by the second SMA wire 112B. Therefore, the force applied by the second SMA wire 112B functions as a restring force. Although an actuation by an SMA wire generally has a disadvantage of a response speed lower than a voice coil actuation employed to a conventional optical image stabilizing system, the differential drive method can improve the response speed.
Contrary to the conventional optical image stabilizing system shown in Figure 6, since the optical image stabilizing system according to the embodiment of the present invention has the SMA wires of which both ends are connected to the power supply terminals 114, electrical current can be easily applied to the SMA wires. In the conventional optical image stabilizing system shown in Figure 6, one end of the SMA  wire is connected to the power supply terminal on the substrate, while the other end is connected to the optics base. Therefore, a contact point, which can supply an electrical current, has to be provided to the optics base. Therefore, the design of the optics base and the assembly process of the optical image stabilizing system may become more complicated.
The range of the length reduction of the SMA wire is preferably up to about 3%considering the maintenance of the shape memory function, the stability of the crystal structure, and the durability. Since the SMA wires of the optical image stabilizing system of the present application are longer than the SMA wires of the conventional optical image stabilizing system shown in Figure 6, the ranges of the length reduction of the SMA wires, i.e., the displacement of the optical element 104 can be increased compared to that of the conventional optical image stabilizing system. For example, regarding the optical image stabilizing systems having the same area, the SMA wire of the present invention shown in Figure 1 is twice as long as the conventional SMA wire shown in Figure 6. Assuming that the amount of the length reduction of the SMA wire of the conventional optical image stabilizing system shown in Figure 6 is x, the displacement of the optical element in the direction toward the center of the optical element is x/√ (2) because the angle between the displacement of the optical element and the direction of the length reduction of the SMA wire is 45°. Since the amount of the length reduction of the SMA wire of the present invention shown in Figure 1 is 2x, the displacement of the optical element in the direction toward the center of the optical element is 2x/√ (2) = √ (2) x. Therefore, the optical image stabilizing system of the present invention can realize a larger displacement of the optical element compared to the conventional optical image stabilizing system, and therefore address a larger camera shake.
Contrary to the conventional optical image stabilizing system shown in Figure 6, since the optical image stabilizing system according to the embodiment of the present invention has the SMA wire of which both ends are connected to the power supply terminals 114, the SMA wire can apply forces in two directions to one tension pole. The force applied to the optics base 106 via the tension pole is the resultant force of the forces in the two directions. For example, if a force f is applied to the tension pole by reducing the length of the SMA wire, the component of the force in the direction toward the center of the optical element of the conventional optical image stabilizing system shown in Figure 6 is f/√ (2) . On the other hand, since the two forces f in directions toward the ends of the SMA wire, respectively, are applied to the tension pole of the optical image stabilizing system according to the embodiment of the present invention  shown in Figure 1, the component of the force toward the center of the optical element is 2f/√ (2) = √ (2) f. Therefore, the optical image stabilizing system according to the embodiment of the present application can move the optical element with a force larger than the conventional optical image stabilizing system and therefore, improve the response speed and carry out a displacement of a larger optical element.
Considering the displacement of the optical element and the force applied to the optics base as discussed above, it is shown that the smaller the number of the SMA wires is, the larger the component of the displacement and the component of the force toward the center of the optical element are. Furthermore, more SMA wires will increase parameters to be controlled and therefore make the control more complicated. The device also will become larger. Since it is preferable to drive the optical element by the differential drive method as discussed above, the number of the SMA wires is preferably even and the SMA wires are preferably arranged in symmetry with respect to the center of the optical element. The number of the SMA wires may be other than four, for example, the number may be three or five or more. However, considering the above discussions, the number of the SMA wires is preferably four as shown in Figure 1.
Figure 4 shows a flow chart of a method 400 of fabricating the optical image stabilizing system according to the embodiment of the present application shown in Figure 1.
In step 402, the substrate 102 is provided. The substrate 102 is made from a conventional material such as glass, silicon, and metal. A region to face the optical element 104 has a structure which allows light transmitting the optical element 104 to pass through. For example, if the substrate 102 is made from glass, no opaque structures preventing light from passing through the substrate 102 are provided in this region. If the substrate 102 is made from an opaque material such as silicon or metal, a through hole may be provided in this region in order to allow light to pass through.
In step 404, the optical element 104 and the optics base 106 configured to support the optical element 104 are provided. The optical element 104 may be a lens made from, for example, plastic or glass. The optical element 104 is supported by the optics base 106. The optics base 106 may be made from a conventional material such as glass, silicon, or metal.
The first and  second tension poles  110A, 110B are formed at the periphery of the optics base 106 and on the first straight line 120 passing through the center 124 of the optical element 104 such that the center 124 of the optical element 104 is positioned between the first and  second tension poles  110A, 110B. The third and fourth tension  poles 110C, 110D are provided at the periphery of the optics base 106 and on the second straight line 122 passing through the center 124 of the optical element 104 and intersecting with the first straight line 120 at a predetermined angle, preferably being orthogonal to the first straight line, such that the center 124 of the optical element 104 is positioned between the third and fourth tension poles 110C, 110D.
In step 406, the one or more support members 108 supporting the optics base 106 are provided on the surface of the substrate 102. The support members 108 may be, for example, three balls. In this case, the optical element 104 and the optics base 106 may move in a direction parallel to the surface of the substrate 102 due to the rotation of the balls. Alternatively, the supporting members 108 may be, for example, protrusions provided on the surface of the substrate 102 and in contact with the optics base 106 at the apexes of the protrusions, and providing smooth sliding movement of the optics base 106. If the supporting members 108 are the protrusions, there is an advantage in which the device is easily assembled because the supporting members 108 are fixed on the substrate 102. In an alternative example, the supporting members 108 may be spring structures which can suspend the optics base 106.
In step 408, the optics base 106 is supported by the supporting members 108 such that the optical element 104 and the optics base 106 are separated from the surface of the substrate 102 and moveable in a direction parallel to the surface of the substrate 102. For example, one or more ferromagnetic members may be provided on either one of the substrate 102 or the optics base 106, and one or more magnets may be provided on the other of the substrate 102 or the optics base 106 such that the magnets face the ferromagnetic members, respectively. In this case, the ferromagnetic members and the magnets cause an attractive force between the optics base 106 and the substrate 102, which allows the optics base 106 to be easily held at and aligned to a predetermined position relative to the substrate 102. In particular, if the supporting members 108 are the balls, it is advantageous to hold the optics base 106 by the magnets because the supporting members108 are not fixed to both of the substrate 102 and the optics base 106.
In step 410, one ends of the first to fourth SMA wires 112A to 112D are fixed to the power supply terminals 114 on the substrate 102, respectively.
In step 412, the first to fourth SMA wires 112A to 112D are half-wrapped on the first to fourth tension poles 110A to 110D and are inserted in through holes 422 provided on the substrate 102, respectively. Weights 424 having masses identical to each other are attached at the other ends of the first to fourth SMA wires 112A to 112D. Due to the gravity applied to the weights 424, identical tensions are applied to the first  to fourth SMA wires 112A to 112D. Then the power supply terminals 114 are inserted to the through holes 422 to fix the first to fourth SMA wires 112A to 112D. Figure 5 shows an expanded perspective view when the step 412 is carried out for the first SMA wire 112A. Since electrical currents are applied to the first to fourth SMA wires 112A to 112D via the power supply terminals 114 during the operation of the optical image stabilizing system 100, at least surfaces of the through holes 422 are preferably covered with an insulation material.
In this case, since the same tensions are applied to all of the first to fourth SMA wires 112A to 112D, the center of the optical element 104 can be aligned to the origin of the optics. If the same amounts of electrical currents are applied to the first to fourth SMA wires 112A to 112D to heat the SMA wires, respectively, the amounts of length reductions of the first to fourth SMA wires 112A to 112D and the forces applied to the optics base 106 are identical to each other. Therefore, the control of the displacement of the optical element 104 becomes significantly easy.
In step 414, the weights 424 and residual portions of the first to fourth SMA wires 112A to 112D are removed to obtain the optical image stabilizing system 100.
Although the embodiments of the present invention are illustrated above, those skilled in the art would easily understand that various modifications and improvements can be carried out without deviating from the spirit and the scope of the present invention.
Reference numbers
100: Optical image stabilizing system
102: Substrate
104: Optical element
106: Optics base
108: Supporting member
110A to 110D: First to fourth tension poles
112A to 112D: First to fourth shape memory alloy (SMA) wires
114: Power supply terminal
120: First straight line
122: Second straight line
124: Center of the optical element 104
126: Hall element
126A: Groove
128: Magnet
422: Through hole
424: Weight
600: Conventional optical image stabilizing system
602: Substrate
604: Optical element
606: Optics base
608: Supporting member
610A to 610D: First to fourth tension poles
612A to 612D: First to fourth shape memory alloy (SMA) wires

Claims (12)

  1. An optical image stabilizing system comprising:
    a substrate;
    an optical element separated from a surface of the substrate;
    an optics base supporting the optical element and separated from the surface of the substrate;
    one or more supporting members disposed between the substrate and the optics base and supporting the optics base such that the optical element and the optics base are moveable in a direction parallel to the surface of the substrate;
    first and second tension poles disposed on a periphery of the optics base and on a first straight line on which a center of the optical element is positioned, wherein the center of the optical element is positioned between the first and second tension poles;
    third and fourth tension poles disposed on the periphery of the optics base and on a second straight line on which the center of the optical element is positioned, wherein the second straight line intersects the first straight line at a predetermined angle, and wherein the center of the optical element is positioned between the third and fourth tension poles; and
    first to fourth shape memory alloy wires which are tensioned by fixing both ends on the substrate, respectively, wherein the first to fourth shape memory alloy wires are half-wrapped on the first to fourth tension poles, respectively,
    wherein the first to fourth shape memory alloy wires are configured to apply forces to the optics base in a direction toward the center of the optical element via the first to fourth tension poles, respectively.
  2. The optical image stabilizing system according to Claim 1, wherein the first to fourth shape memory alloy wires are configured to reduce lengths by heat, respectively.
  3. The optical image stabilizing system according to Claim 2, wherein the heating is carried out by applying electrical currents through the first to fourth shape memory alloy wires, respectively.
  4. The optical image stabilizing system according to Claim 1, further comprising:
    one or more Hall elements provided on one surface of the substrate or the optics base; and
    one or more magnets provided on the other surface of the substrate or the  optics base such that the magnets face the Hall elements, respectively,
    wherein the one or more Hall elements are configured to output signals related to a relative position of the optics base relative to the substrate.
  5. The optical image stabilizing system according to Claim 1, further comprising:
    one or more ferromagnetic members provided on one surface of the substrate or the optics base; and
    one or more magnets provided on the other surface of the substrate or the optics base such that the magnets face the ferromagnetic members, respectively,
    wherein the one or more ferromagnetic members and the one or more magnets are configured to cause attractive forces between the optics base and the substrate, respectively.
  6. The optical image stabilizing system according to Claim 1, further comprising:
    one or more Hall elements provided on one surface of the substrate or the optics base;
    one or more ferromagnetic members provided on the same surface of the substrate or the optics base as the surface on which the Hall elements are provided; and
    one or more magnets provided on the other surface of the substrate or the optics base such that the magnets face the Hall elements and the ferromagnetic members, respectively,
    wherein the one or more Hall elements are configured to output signals related to a relative position of the optics base relative to the substrate, and
    wherein the one or more magnets and the one or more ferromagnetic members are configured to cause attractive forces between the optics base and the substrate, respectively.
  7. A method of fabricating an optical image stabilizing system, comprising the steps of:
    providing a substrate;
    providing an optical element and an optics base supporting the optical element, wherein the optics base comprises:
    first and second tension poles on a periphery of the optics base and on a first straight line on which a center of the optical element is positioned, wherein the center of the optical element is positioned between the first and second tension poles; and
    third and fourth tension poles disposed on the periphery of the optics base and on a second straight line on which the center of the optical element is positioned, wherein the second straight line intersects the first straight line at a predetermined angle, and wherein the center of the optical element is positioned between the third and fourth tension poles,
    providing one or more supporting members on a surface of the substrate, the one or more supporting members supporting the optics base;
    supporting the optics base by the one or more supporting members such that the optical element and the optics base are separated from the surface of the substrate and are moveable in a direction parallel to the surface of the substrate;
    fixing one ends of first to fourth shape memory alloy wires on the substrate, respectively,
    attaching weights at the other ends of the first to fourth shape memory alloy wires, respectively, and fixing the other ends of the first to fourth shape memory alloy wires on the substrate, wherein the weights have masses identical to each other, wherein the tensions are applied to the first to fourth shape memory alloy wires by gravity acting on the weights to half-wrap the first to fourth shape memory alloy wires on the first to fourth tension poles, respectively, and
    removing the weights from the first to fourth shape memory alloy wires.
  8. The method of fabricating an optical image stabilizing system according to Claim 7, wherein the first to fourth shape memory alloy wires are configured to reduce their lengths by heating.
  9. The method of fabricating an optical image stabilizing system according to Claim 8, wherein the heating is configured to be carried out by applying electric currents to the first to fourth shape memory alloy wires, respectively.
  10. The method of fabricating an optical image stabilizing system according to Claim 7, further comprising:
    providing one or more Hall elements on one surface of the substrate or the optics base; and
    providing one or more magnets on the other surface of the substrate or the optics base such that the magnets face the Hall elements, respectively,
    wherein the one or more Hall elements are configured to output signals related to a relative position of the optics base relative to the substrate.
  11. The method of fabricating an optical image stabilizing system according to Claim 7, further comprising:
    providing one or more ferromagnetic members on one surface of the substrate or the optics base; and
    providing one or more magnets on the other surface of the substrate or the optics base such that the magnets face the ferromagnetic members, respectively,
    wherein the one or more ferromagnetic members and the one or more magnets are configured to apply an attractive force between the optics base and the substrate, and
    wherein in the step of supporting the optics base by the one or more supporting members, the one or more magnets hold the optics base at a predetermined position relative to the substrate.
  12. The method of fabricating the optical image stabilizing system according to Claim 7, further comprising:
    providing one or more Hall elements on one surface of the substrate or the optics base;
    providing one or more ferromagnetic member on the same surface of the substrate or the optics base as the surface on which the Hall elements were provided; and
    providing one or more magnets on the other surface of the substrate or the optics base such that the magnets face the Hall elements and the ferromagnetic members, respectively,
    wherein the one or more Hall elements are configured to output signals related to a relative position of the optics base relative to the substrate,
    wherein the one or more ferromagnetic members and the one or more magnets are configured to apply an attractive force between the optics base and the substrate, and
    wherein in the step of supporting the optics base by the one or more supporting members, the one or more magnets hold the optics base at a predetermined position relative to the substrate.
PCT/CN2020/070451 2020-01-06 2020-01-06 Optical image stabilizing system comprising shape memory alloy wires and methods of fabricating thereof WO2021138766A1 (en)

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