Anti-shake mechanism, camera module, mobile terminal

Abstract

The present invention provides an image stabilization mechanism that is efficient, consumes little power, is less susceptible to resonance, has a small attitude difference, and is low cost. The image stabilization mechanism includes a base 31, a movable part 32 provided on the base 31 facing the optical axis direction of the camera module 2, the movable part 32 being supported on the base 31 so as to be movable in each of a first direction X perpendicular to the optical axis direction and a second direction Y perpendicular to the optical axis direction and the first direction X, and a drive part 33 that connects the base 31 and the movable part 32 and generates a drive force for moving the movable part 32 in at least one of the first direction X and the second direction Y. The movable part 32 is equipped with an imaging element 32b1, and the driving part 33 has a pair of driving wires 331 that are deformable in the longitudinal direction, one pair facing the first direction X and the other pair facing the second direction Y, both ends of the driving wires 331 are fixed to the base 31, and an intermediate part of the driving wires 331 is attached to the movable part 32. The driving wires are deformed to move the movable part 32 in a direction approaching both ends of the driving wires 331, forming an anti-shake mechanism 3.

Description

[Technical field]

[0001] The present invention relates to an image stabilization mechanism incorporated in a camera module included in a device such as a mobile terminal (for example, a smartphone or tablet), and to a camera module and a mobile terminal that include the same. [Background technology]

[0002] As a conventional technique related to the present invention, for example, there is an optical image stabilization (OIS) mechanism described in CN108780207A.

[0003] In this prior art, a dynamic platform with an image sensor is configured to move relative to a static platform in multiple directions perpendicular to the optical axis of the camera lens. Specifically, the OIS mechanism includes a voice coil motor (VCM). The VCM includes an image sensor frame member as the dynamic platform, a frame of the VCM as the static platform, and multiple OIS coils. The OIS coils are mounted on the image sensor frame member within the magnetic field of a magnet to generate a force that moves the dynamic platform in multiple directions perpendicular to the optical axis of the camera lens.

[0004] The voice coil motor used as the driving source in this configuration has low efficiency and consumes a lot of power, and the combination of the dynamic platform and the static platform in this configuration has problems such as being prone to resonance, large attitude difference, and high cost. Summary of the Invention [Problem to be solved by the invention]

[0005] In view of this, an object of the present invention is to provide an image stabilization mechanism that is superior to conventional techniques, has high efficiency, consumes less power, is less susceptible to resonance, reduces posture differences, and is low cost, as well as a camera module and a mobile terminal equipped with the same. [Means for solving the problem]

[0006] One form of the present invention is an image stabilization mechanism built into a camera module, comprising: a base; a movable part provided to face the base in an optical axis direction of the camera module, the movable part being supported so as to be movable relative to the base in a first direction perpendicular to the optical axis direction, and a second direction perpendicular to the optical axis direction and the first direction; and a drive part connecting the base and the movable part and generating a drive force for moving the movable part in at least one of the first direction and the second direction, wherein the movable part comprises an image sensor, and the drive part has a pair of drive wires facing the first direction and a pair of drive wires facing the second direction, both ends of the drive wires are fixed to the base and an intermediate portion of the drive wire is attached to the movable part, and the image stabilization mechanism moves the movable part in a direction approaching both ends of the drive wires by deforming at least one of the drive wires in the longitudinal direction.

[0007] The drive wire may be configured to contract in the length direction when heated.

[0008] Furthermore, when one of the pair of drive wires contracts, the other of the pair of drive wires can extend.

[0009] The drive wire may be made of metal, but may also be made of other materials capable of implementing the present invention, and is preferably made of a shape memory alloy.

[0010] In addition, the base is provided with a power supply electrode, and both ends of the drive wire are fixed to the base by being fixed to the power supply electrode and are electrically connected to the power supply electrode, and the drive wire generates heat when electricity is passed through it, thereby causing the contraction.

[0011] In addition, the movable part has a rectangular shape when viewed in the optical axis direction, and the movable part has wire bend portions at its four corners that protrude toward the base, and the intermediate portion of the drive wire abuts against the side of the wire bend portion, thereby attaching the intermediate portion of the drive wire to the movable part.

[0012] The wire bend portion may include a groove or a protrusion that restricts the drive wire from being misaligned in the optical axis direction.

[0013] Furthermore, the pair of driving wires facing each other in the first direction are arranged symmetrically in the first direction, and the pair of driving wires facing each other in the second direction are arranged symmetrically in the second direction, and the center of the imaging element as viewed in the optical axis direction coincides with the central positions of the pair of driving wires facing each other in the first direction and the pair of driving wires facing each other in the second direction.

[0014] The camera module may further include a vibration detection unit that detects vibrations applied to the camera module, and a control unit that performs control in response to the vibrations detected by the vibration detection unit.

[0015] In addition, the control unit can cause the drive unit to input energy to deform the drive wire depending on the magnitude of vibration detected by the vibration detection unit, and can stop the input of energy when the vibration detection unit no longer detects vibration.

[0016] In addition, one of the base and the movable part may be equipped with a permanent magnet, and the other may be equipped with a Hall element, and the Hall element may be configured to detect the positional relationship of the movable part relative to the base in at least one of the first direction and the second direction.

[0017] Another aspect of the present invention is a camera module incorporating the image stabilization mechanism.

[0018] Another aspect of the present invention is a mobile terminal including the camera module. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic diagram showing how to prevent camera shake in a smartphone. [Diagram 2] FIG. 2 is a schematic diagram showing the process in the image stabilization mechanism. [Diagram 3] FIG. 3 is a vertical cross-sectional view showing, in a simplified manner, parts necessary for explanation of a camera module provided with an image stabilization mechanism according to an embodiment of the present invention. [Figure 4] FIG. 4 shows the image stabilization mechanism, as viewed from the rear of the base plate of the movable portion. [Diagram 5] FIG. 5 is a diagram showing parts necessary for explanation extracted from FIG. [Figure 6] FIG. 6 is a diagram showing parts necessary for explanation extracted from FIG. [Figure 7A] FIG. 7A is a side view showing an imaging section of the movable section in the image stabilization mechanism. [Figure 7B] FIG. 7B is a side view showing the base and movable part (excluding the imaging part) in the image stabilization mechanism. [Figure 8A] FIG. 8A is a plan view showing a base portion of the image stabilization mechanism. [Figure 8B] FIG. 8B is a right side view showing the base of the image stabilization mechanism. [Figure 9A] FIG. 9A is a right side view showing the movable portion (excluding the imaging element support portion) of the image stabilization mechanism. [Figure 9B] FIG. 9B is a bottom view showing the movable portion (excluding the imaging element support portion) of the image stabilization mechanism. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] An image stabilization mechanism 3 according to one embodiment of the present invention will be described with reference to the drawings. Note that the "optical axis direction" hereinafter refers to the optical axis direction of the camera module 2. The subject side is the front (left direction in FIG. 3), and the imaging element 32b1 side is the rear (right direction in FIG. 3).

[0021] The image stabilization mechanism 3 of this embodiment is built into a camera module 2 equipped in a mobile terminal 1 (e.g., a smartphone, a tablet) or the like. First, an overview of the image stabilization function in the mobile terminal 1 is shown in Figs. 1 and 2. The image stabilization function itself is well known, so it will be explained briefly. As shown in Fig. 1, vibrations may be transmitted from a user's hand or the like to the mobile terminal 1 (a smartphone is exemplified). These vibrations are transmitted to the camera module 2. The vibrations have a rotational motion component, for example, as indicated by the arrow in Fig. 1. It should be noted that they may also have a linear movement component.

[0022] 2, a gyro sensor 11 and a servo driver 12 are provided inside the mobile terminal 1, and an actuator 13 and a sensor 14 are provided in the camera module 2. When vibration is transmitted to the camera module 2, the gyro sensor 11 detects it, and the servo driver 12 drives the actuator 13 under the detection of the sensor 14, and by looping this (servo loop), the image captured through the lens and projected onto the imaging element 32b1 can be made blur-free.

[0023] 3 shows a simplified configuration of the camera module 2. A lens support section 21 is supported on the mobile terminal 1. Although not shown, the lens support section 21 is provided with a lens, an aperture, and an autofocus mechanism. An imaging element 32b1 is provided behind the lens support section 21 in the optical axis direction to receive imaging light that passes through the lens and forms an image. This imaging element 32b1 is provided in the image stabilization mechanism 3.

[0024] The image stabilization mechanism 3 includes a base 31, a movable part 32, and a drive part 33. The base 31 is a plate-like part fixedly provided in the image stabilization mechanism 3 (and the camera module 2). As shown in FIG. 7B, the base 31 includes a rigid flat base plate 311 and a flexible printed circuit (Flexible Printed Circuits, FPC) 312 that is bonded to the front surface of the base plate 311 and is more flexible than the base plate 311 (see FIGS. 8A and 8B). The base plate 311 has a quadrangular shape (specifically, a rectangular shape) when viewed in the optical axis direction. A portion of the flexible circuit 312 that overlaps with the base plate 311 has the same shape as the base plate 311. The base 31 includes a power supply electrode 313. The power supply electrode 313 is fixed to the base plate 311 so as to protrude forward in the optical axis direction. A rectangular wave current is supplied to the power supply electrode 313 from outside the image stabilization mechanism 3 in the camera module 2. The current to be supplied may be a direct current or a current having a waveform other than a square wave.

[0025] The movable part 32 is a plate-like part provided on the base part 31 so as to face each other in the optical axis direction. The movable part 32 includes a flat base plate 321. The base plate 321 has a quadrangular shape (specifically, a rectangular shape) when viewed in the optical axis direction. As shown in FIGS. 7A and 7B, the movable part 32 includes a movable mechanism part 32a and an imaging part 32b which is separate from the movable mechanism part 32a and which is attached to the movable mechanism part 32a by, for example, adhesion, thereby being integrated with the movable mechanism part 32a. The imaging part 32b includes an imaging element 32b1.

[0026] The movable part 32 is supported relative to the base part 31 so as to be movable in each of a first direction X perpendicular to the optical axis direction and a second direction Y perpendicular to the optical axis direction and the first direction X. In the description of this embodiment, the left-right direction shown in Fig. 4 is defined as the first direction X, and the up-down direction is defined as the second direction Y. Note that the movable part 32 is also movable in a direction resulting from a combination of the first direction X and the second direction Y (a diagonal direction in Fig. 4 at any angle).

[0027] As shown in FIG. 9A and FIG. 9B, the movable part 32 has wire bends 322 at four corners, which protrude rearward (toward the base part 31) from the base plate 321. That is, the wire bends 322 are provided at four locations in the movable part 32. The wire bends 322 in this embodiment are cylindrical protrusions protruding from the rear surface of the base plate 321. The wire bends 322 are formed from an insulating material such as resin. The driving wire 331 is hooked to the curved side surface of the wire bends 322. Specifically, as shown in FIG. 4, the driving wire 331 is hooked along a part of the outer part 322a facing outward of each wire bend 322 based on a virtual square formed by the four wire bends 322. This causes the driving wire 331 to bend when viewed in the optical axis direction. In this embodiment, as shown in FIG. 4, the driving wire 331 is bent at an acute angle, but may be bent at a right angle or an obtuse angle. The wire bend portion 322 has a groove 3221 that restricts the driving wire 331 from shifting in the optical axis direction (see FIG. 9A). The groove 3221 is provided on the side surface of the wire bend portion 322 so as to be perpendicular to the axial direction of the cylindrical wire bend portion 322. Note that a protrusion for hooking the driving wire 331 may be provided instead of the groove 3221. Alternatively, the entire outer circumferential surface of the wire bend portion 322 may be curved, and the driving wire 331 may be hooked on a recessed portion of the curved surface.

[0028] A rotating portion 323 is provided at the axial end of the wire bend portion 322. The rotating portion 323 includes a rotating body (specifically, a ball) embedded in the wire bend portion 322 so that a part of the rotating portion protrudes from the end face facing the base portion 31. The rotating portion 323 abuts against the front surface (flat surface) of the base portion 31 and rotates relative to the front surface of the base portion 31. This causes the movable portion 32 to move in a planar direction perpendicular to the optical axis direction while maintaining a constant distance from the base portion 31.

[0029] The base 31 and the movable part 32 are held in position in the optical axis direction while allowing movement in the planar direction so as not to separate in the optical axis direction. Specifically, the position is held in the optical axis direction by magnetic attraction between a plurality of permanent magnets 324 (four in this embodiment) provided on the rear surface of the movable part 32 and a magnetic body 314 (e.g., steel material) provided on the front surface of the base 31 at a position facing the plurality of permanent magnets 324. The attraction force between the permanent magnet 324 and the magnetic body 314 is set so as to act even when the movable part 32 is displaced to the maximum extent relative to the base 31. Although not shown, the base 31 and the movable part 32 are also held in position in the planar direction by providing a stopper or the like that abuts against the movable part 32 to restrict movement in the planar direction beyond the driving range of the driving part 33.

[0030] As shown in FIG. 9B, the movable part 32 is provided with a cylindrical wire guide 325 in addition to the wire bend part 322. The wire guide 325 protrudes rearward from the base plate 321 of the movable part 32. The wire guide 325 is made of an insulating material such as resin. As shown in FIG. 4 and FIG. 5, which shows a partial configuration extracted from FIG. 4, the wire guide 325 is located between the power supply electrode 313 and the wire bend part 322 (the wire closest to the power supply electrode 313 on the path) on the path through which each driving wire 331 passes. Each driving wire 331 (a combination of the driving wire 331 shown in FIG. 5 and a symmetrical driving wire 331 (not shown)) that is a pair of driving wires facing each other in the first direction X abuts against the outer circumferential surface of the wire guide 325. For this reason, two wire guides 325 are provided facing each other in the second direction Y. The contact state between the outer circumferential surface of the wire guide 325 and each driving wire 331 changes according to the extension and contraction of each driving wire 331 and the movement of the movable part 32 relative to the base part 31. The wire guide 325 suppresses the wobble of each driving wire 331 in a direction intersecting the extending direction between the power supply electrode 313 and the wire bend part 322.

[0031] Here, in this embodiment, for convenience of arrangement, a cylindrical wire guide 315 is also provided on the base 31. This wire guide 315 protrudes forward from the base plate 311 of the base 31. The wire guide 315 is formed of an insulating material such as resin. The wire guide 315 penetrates a through hole 315h provided in the flexible substrate 312 shown in FIG. 8A. As shown in FIG. 4 and FIG. 6 which shows a partial configuration extracted from FIG. 4, this wire guide 315 is located between the power supply electrode 313 and the wire bend portion 322 (the one closest to the power supply electrode 313 on the path) on the path through which each driving wire 331 passes. Each driving wire 331 of the pair (two wires) facing the second direction Y abuts against the outer circumferential surface of the wire guide 315. For this reason, two wire guides 315 are provided facing the first direction X. The contact state between the outer circumferential surface of the wire guide 315 and each of the driving wires 331 changes according to the extension and contraction of each of the driving wires 331. Similar to the wire guide 325 of the movable part 32, this wire guide 315 suppresses the wobble of each of the driving wires 331 in a direction intersecting the extending direction between the power supply electrode 313 and the wire bend part 322.

[0032] One of the base 31 and the movable part 32 (the movable part 32 in this embodiment) is equipped with a permanent magnet 324, and the other (the base 31 on the fixed side of the image stabilization mechanism 3 in this embodiment) is equipped with a Hall element 316. As shown in Figs. 8A and 8B, the Hall element 316 is one of a pair (two pieces) of magnetic bodies 314 extending in the first direction X (the upper magnetic body 314 in Fig. 8A) and one of a pair (two pieces) of magnetic bodies 314 extending in the second direction Y (the left magnetic body 314 in Fig. 8A), and is provided so as to be sandwiched between the two magnetic bodies 314 arranged in each direction. The Hall element 316 detects magnetism emitted by the permanent magnet 324 provided at a position facing the magnetic body 314, thereby detecting the positional relationship of the movable part 32 with respect to the base 31 in the first direction X and the second direction Y. In this manner, the Hall element 316 is arranged so as to be sandwiched between two magnetic bodies 314 arranged in each direction, so that the position of the base 31 and the movable part 32 in the optical axis direction can be maintained by the attractive force (magnetic force) between the permanent magnet 324 and the magnetic body 314, and the positional relationship of the movable part 32 with respect to the base 31 can be detected in the same part.

[0033] The driving unit 33 is a part that connects the base 31 and the movable unit 32 and generates a driving force for moving the movable unit 32 in at least one of the first direction X and the second direction Y. As shown in FIG. 4, the driving unit 33 has a pair (two wires) of driving wires 331 facing the first direction X and a pair (two wires) facing the second direction Y. That is, four driving wires 331 are used. The driving wires 331 are configured to be deformable (stretchable) in the length direction. Specifically, the driving wires 331 are contracted in the length direction by being heated, and are made of a shape memory alloy (SMA) in this embodiment. The multiple driving wires 331 are arranged with a shift in the front and rear direction in the optical axis direction. Therefore, they do not interfere with each other as they expand and contract. It is sufficient that the driving wires 331 are arranged with a shift in the front and rear direction at least in the portion where the driving wires 331 cross each other as viewed in the optical axis direction and around the portion. Since the driving wire 331 is thin, even if it is arranged with a deviation in the optical axis direction, it hardly affects the dimension of the image stabilization mechanism 3 in the optical axis direction. The driving wire 331 is, for example, a linear wire with a circular cross section. Such shape memory alloy wires are generally available and are therefore advantageous in terms of cost. The thickness of the driving wire 331 is constant along the length. The material is also homogeneous along the length. The cross-sectional dimensions can be set to various values, for example, a diameter of 50 μm. The cross-sectional dimensions can be determined in consideration of the required length from one end of the driving wire 331 to the other end, the response accuracy of the extension and contraction, durability, and the like. When the driving wire 331 is no longer heated, it returns to its original length by natural cooling. In other words, when the heating is no longer applied, it expands in the length direction. This expansion can also be achieved by applying an external force to the driving wire 331. The external force is, for example, a tensile force generated by the contraction of the other driving wire 331 that constitutes a pair (two wires).

[0034] Both ends of the drive wire 331 (more specifically, both ends of the portion of the drive wire 331 where a drive force is generated) are fixed to the base 31 (power supply electrode 313), and the middle portion of the drive wire 331 is hooked on a wire bend portion 322 so that it is displaceably attached to the movable portion 32. The tension of the drive wire 331 in a free state (neither contracted nor extended) is set to a degree that does not cause slack. By keeping the drive wire 331 in a taut state in a free state, quick response can be ensured. The tension can be set taking into consideration temperature changes in which the mobile terminal 1 is expected to be used.

[0035] 4, a pair (two pieces) of driving wires 331 facing in a first direction X are arranged symmetrically in the first direction X, and a pair (two pieces) of driving wires 331 facing in a second direction Y are arranged symmetrically in the second direction Y. The pair of driving wires 331 facing in the first direction X and the pair of driving wires 331 facing in the second direction Y are arranged so that the center of the image sensor 32b1 as viewed in the optical axis direction (the intersection of diagonals in a rectangle or square) coincides with the central position. By deforming at least one of the driving wires 331 (specifically, the driving wire 331 is heated and contracted), the movable part 32 can be moved in a direction approaching both ends of the driving wire 331.

[0036] In this embodiment, the driving wire 331 is heated by using resistance heat generated by passing current through the driving wire 331 itself. Therefore, both ends of the driving wire 331 are electrically connected to the power supply electrode 313 in the base 31. The connection of the driving wire 331 to the power supply electrode 313 may be made by physical bonding such as tying, clamping, or screwing, or may be made by bonding using solder or a conductive adhesive. The side of the power supply electrode 313 to which one end of the driving wire 331 is fixed is a positive electrode, and the side to which the other end is fixed is a negative electrode. In addition, the middle part of the driving wire 331 abuts against the side of the wire bend part 322. The driving wire 331 is contracted by generating heat by itself due to the current supplied from the power supply electrode 313. Therefore, in this embodiment, the driving wire 331 is contracted not partially but over its entire length. When one of a pair (two) of driving wires 331 facing each other in the X and Y directions contracts due to energization, the other is not energized and is in a non-heated state, and does not contract or extend spontaneously. However, the other driving wire 331 receives a force accompanying the contraction of one driving wire 331 and is extended by the elasticity of the other driving wire 331 itself. To explain the operation in detail, one driving wire 331 that contracts due to energization transmits a driving force to the wire bend portion 322 to which the driving wire 331 is hooked. In response to this, the movable part 32 moves. As a result, the other driving wire 331 (not energized) that is hooked to another wire bend portion 322 provided in the moving movable part 32 is forcibly extended. Thus, in this embodiment, when one of the driving wires 331 that constitute a pair contracts, the other of the driving wires 331 that constitute the pair is configured to extend. As a result, the driving force generated by one of the driving wires 331 is not hindered by the other of the driving wires 331. Furthermore, one of the driving wires 331 contracts while the tension of the other of the driving wires 331 is applied to the movable part 32, so that the movable part 32 can be moved stably. From the outside, the pair of driving wires 331 (two in each direction) facing each other in the X and Y directions appear to be linked because one (one) contracts and the other (one) extends.

[0037] Of the pair (two) of drive wires 331 facing in the first direction X (left-right direction in the figure) shown in FIG. 4, one is extracted and shown in FIG. 5 for ease of explanation. Of the pair (two) of drive wires 331 facing in the first direction X, the one in the positional relationship facing the one shown in FIG. 5 operates 180° symmetrically (opposite left-right operation in the figure) with respect to the one shown in the optical axis direction. As described above, the pair (two) of drive wires 331 are controlled so that when one wire contracts, the other wire does not contract, so that the contraction forces of both wires (two wires) do not oppose each other at the same time. Of the pair (two) of drive wires 331 facing in the second direction Y (up-down direction in the figure), one is extracted and shown in FIG. 6 for ease of explanation. Moreover, of the pair (two) drive wires 331 facing in the second direction Y, the one positioned opposite to the one shown in Fig. 6 operates 180° symmetrically as viewed in the optical axis direction with respect to the one shown in the figure (operation upside down in the figure). Note that each of the pair of drive wires 331 facing in the second direction Y operates 90° symmetrically as viewed in the optical axis direction with respect to the one shown in Fig. 5 (see Fig. 6). For this reason, the following detailed description will be given only with reference to Fig. 5.

[0038] 5 (one of a pair), first, in the positional relationship shown in the figure, extends diagonally upward to the right from the upper left power supply electrode 313 through the upper wire guide 325 to the upper right wire bend portion 322 as a first path 331a. At the upper right wire bend portion 322, the drive wire 331 is bent downward, and extends downward (directly below) to the lower right wire bend portion 322 as a second path 331b. At the lower right wire bend portion 322, the drive wire 331 is bent left. Next, as a third path 331c, the drive wire 331 extends diagonally upward to the left from the lower right wire bend portion 322 through the lower wire guide 325 to the lower left power supply electrode 313. In this manner, the path (the continuous first path 331a to the third path 331c) through which the driving wire 331 of this embodiment passes is substantially trapezoidal (the first path 331a and the third path 331c corresponding to the "legs" are symmetrical in shape), the wire bend portion 322 is at the intersection between the "lower base" (corresponding to the second path 331b) of the trapezoid and the "legs", and the driving wire 331 is arranged so as to follow each side of the trapezoid except for the "upper base". Note that the driving wire 331 does not need to be arranged along all the sides of the trapezoid (strict trapezoidal shape), and for example, since the driving wire 331 is curved at the wire bend portion 322, it is arranged away from the sides of the trapezoid.

[0039] When the driving wire 331 is energized, the entire driving wire 331 contracts in the length direction. As a result, the driving wire 331 moves as a whole in the left direction of the arrows in the figure along the upper and lower paths (first path 331a and third path 331c) shown in the figure (more specifically, the first path 331a is diagonally downward to the left, and the third path 331c is diagonally upward to the left) along each path. The driving wire 331 also moves as a whole in the path on the right side of the figure (second path 331b) as this path contracts. Since the power supply electrode 313 is provided on the fixed base 31, the upper and lower wire bend parts 322 provided on the movable part 32 move in the left direction in the figure. Therefore, the movable part 32 moves in the left direction of the arrow drawn in the center of FIG. 5. On the other hand, when the energization of the driving wire 331 is stopped, the entire driving wire 331 extends in the length direction due to natural cooling. At the same time, the other driving wire 331 (not shown in Fig. 5) of the pair contracts due to its own tension (it can also be contracted by energizing it). Accordingly, the movable part 32 moves in the right direction of the arrow drawn in the center of Fig. 5, in the opposite direction to when electricity is applied.

[0040] The first path 331a and the third path 331c are arranged symmetrically with respect to a virtual line (not shown) along the first direction X. Therefore, the first path 331a and the third path 331c have the same length and the same angle with respect to the virtual line when viewed in the optical axis direction. The angle between the first path 331a and the second path 331b and the angle between the second path 331b and the third path 331c are also equal. By arranging the paths in this way, when the entire driving wire 331 contracts, the two wire bend parts 322 located above and below in the figure, to which the driving wire 331 is hooked, move the same distance along the virtual line. Therefore, the base plate 321 on which the wire bend part 322 is provided also moves the same distance.

[0041] In this embodiment, four drive wires 331 are arranged as shown in FIG. 4. When the movable part 32 is moved in the first direction X, one of the pair (two) drive wires 331 facing the first direction X is energized and the other is de-energized. When the movable part 32 is moved in the second direction Y, one of the pair (two) drive wires 331 facing the second direction Y is energized and the other is de-energized. The drive wire 331 on the first direction X side and the drive wire 331 on the second direction Y side may be energized at the same time. In this case, the movable part 32 can be moved in an oblique direction. By providing a difference in current flowing to the drive wire 331 on the first direction X side and the drive wire 331 on the second direction Y side, the movement angle in the first direction X or the second direction Y can be adjusted.

[0042] As a comparative example, a configuration is presented in which two diagonal points of a movable part formed in a square when viewed in the optical axis direction are set as fixed points, and the other two diagonal points are set as operating points, and the operating points are moved in one direction along the periphery of the movable part and in another direction perpendicular to the one direction by a driving wire made of a shape memory alloy. In this comparative example, four driving wires are arranged to extend linearly along the periphery of the movable part. However, in this comparative example, it is necessary to move two operating points to move the movable part in the desired direction, which makes the current control (on / off) of the four driving wires complicated.

[0043] In contrast, in this embodiment, the movable part 32 can be moved in a desired direction by selectively energizing one of a pair (two) of drive wires 331 facing in the first direction X and one of a pair (two) of drive wires 331 facing in the second direction Y, or by energizing only one of the pair of drive wires 331 facing in the first direction X, or by energizing only one of the pair of drive wires 331 facing in the second direction Y. This makes it possible to realize a high-performance camera shake prevention mechanism 3 while having a simple configuration that is cost-effective. In this embodiment, by using the drive wire 331 as a drive source, the camera shake prevention mechanism 3 can be made less susceptible to resonance than in the past, the posture difference can be reduced, and the cost can be reduced.

[0044] Next, the camera module 2 or a device (mobile terminal 1) equipped with the camera module 2 includes a vibration detection unit that detects vibrations applied to the camera module 2, and a control unit (not shown) that performs control in response to the vibrations detected by the vibration detection unit. A known configuration can be used for the configuration (e.g., the control unit and sensors not specifically mentioned in this description) for controlling the image stabilization mechanism 3 to deal with camera shake of the camera module 2 in the mobile terminal 1. For example, the above-mentioned gyro sensor 11 (see FIG. 1) is used for the vibration detection unit. The control unit causes the drive unit 33 to input energy (current is passed in this embodiment) to heat the drive wire 331 in response to the magnitude of the vibration detected by the vibration detection unit, and stops the input of energy when the vibration detection unit no longer detects vibration.

[0045] The control unit performs control taking into consideration the time difference between energization, which is input to the drive wires 331, and contraction, which is output, thereby improving responsiveness to vibrations applied to the camera module 2 due to camera shake. In addition, the control unit instantly switches between energization of one of a pair of drive wires 331 facing each other in each of the X and Y directions, thereby achieving quick movement of the movable part 32 relative to the base part 31. With the above-mentioned control, it is possible to respond to camera shake of the camera module 2 without affecting the image sensor 32b1.

[0046] To summarize the present embodiment, the present embodiment relates to an image stabilization mechanism 3 built into a camera module 2, the image stabilization mechanism 3 including a base 31, a movable part 32 provided on the base 31 to face the optical axis direction of the camera module 2, the movable part 32 being supported on the base 31 so as to be movable in each of a first direction X perpendicular to the optical axis direction and a second direction Y perpendicular to the optical axis direction and the first direction X, and a mechanism for connecting the base 31 and the movable part 32 and moving the movable part 32 in at least one of the first direction X and the second direction Y. and a driving unit 33 that generates a driving force, the movable unit 32 having an image sensor 32b1, the driving unit 33 having a pair of driving wires 331 facing the first direction X and a pair facing the second direction Y, both ends of the driving wires 331 being fixed to the base 31 and a middle portion of the driving wires 331 being attached to the movable unit 32, and the anti-shake mechanism 3 is configured to move the movable unit 32 in a direction approaching both ends of the driving wires 331 by deforming at least one of the driving wires 331 in the longitudinal direction.

[0047] According to this configuration, by deforming at least one of a pair of drive wires 331 made of a shape memory alloy that are provided to face each other in the X and Y directions, the movable part 32 including the imaging element 32b1 can be moved relative to the base part 31.

[0048] Moreover, the driving wire 331 can be configured to contract in the length direction when heated.

[0049] According to this configuration, the contraction force of the drive wire 331 can be used as a force for moving the movable part 32 relative to the base part 31.

[0050] Furthermore, when one of the pair of driving wires 331 contracts, the other of the pair of driving wires 331 can be extended.

[0051] According to this configuration, the driving force generated by one of the driving wires 331 is not hindered by the other of the driving wires 331 .

[0052] Moreover, the driving wire 331 may be made of a shape memory alloy.

[0053] This configuration allows the drive wire 331 to be made of readily available materials.

[0054] In addition, the base 31 is provided with a power supply electrode 313, and both ends of the driving wire 331 are fixed to the base 31 by being fixed to the power supply electrode 313 and are also electrically connected to the power supply electrode 313, and the driving wire 331 can be configured to contract by generating heat by passing electricity through it.

[0055] According to this configuration, the drive wire 331 contracts by generating heat by itself when electricity is applied, so that a separate heating means for heating the drive wire 331 is not required.

[0056] In addition, the movable part 32 has a rectangular shape when viewed in the optical axis direction, and is provided with wire bend portions 322 at its four corners that protrude toward the base 31, and the middle portion of the driving wire 331 abuts against the side of the wire bend portion 322, thereby attaching the middle portion of the driving wire 331 to the movable part 32.

[0057] According to this configuration, the wire bend portions 322 provided at the four corners of the movable portion 32 make it easy to configure a pair of driving wires 331 facing each other in each of the X and Y directions.

[0058] Moreover, the wire bend portion 322 may include a groove or a protrusion that restricts the drive wire 331 from being displaced in the optical axis direction.

[0059] According to this configuration, the groove or protrusion allows the wire bend portion 322 to stably hold the drive wire 331 in the optical axis direction.

[0060] Furthermore, the pair of driving wires 331 facing the first direction X are arranged symmetrically in the first direction X, and the pair of driving wires 331 facing the second direction Y are arranged symmetrically in the second direction Y, and the center positions of the pair of driving wires 331 facing the first direction X and the pair of driving wires 331 facing the second direction Y coincide with the center of the image pickup element 32b1 as viewed in the optical axis direction.

[0061] According to this configuration, all the drive wires 331 are arranged symmetrically, and the center of the imaging element 32b1 is located at the central position of the arrangement, so that the configuration of the image stabilization mechanism 3 can be simplified.

[0062] The camera module 2 may also include a vibration detection unit (such as a gyro sensor 11) that detects vibrations applied to the camera module 2, and a control unit that performs control in response to the vibrations detected by the vibration detection unit.

[0063] According to this configuration, the control unit performs control in response to vibrations detected by the vibration detection unit, thereby providing a high-performance camera shake prevention mechanism 3.

[0064] In addition, the control unit can cause the drive unit 33 to input energy to deform the drive wire 331 depending on the magnitude of vibration detected by the vibration detection unit, and can stop the input of energy when the vibration detection unit no longer detects vibration.

[0065] According to this configuration, by controlling the input of energy to the drive unit 33 by the control unit, a high-performance camera shake prevention mechanism 3 can be achieved.

[0066] In addition, one of the base 31 and the movable part 32 is equipped with a permanent magnet 324, and the other is equipped with a Hall element 316, and the Hall element 316 can be configured to detect the positional relationship of the movable part 32 with respect to the base 31 in at least one of the first direction and the second direction.

[0067] According to this configuration, the combination of the permanent magnet 324 and the Hall element 316 can simplify the configuration for detecting the moving state of the movable part 32.

[0068] Moreover, this embodiment relates to a camera module 2 incorporating the image stabilization mechanism, and a mobile terminal 1 including the camera module 2.

[0069] According to the present embodiment configured as described above, the movable part 32 including the imaging element 32b1 can be moved relative to the base part 31 by a pair of drive wires 331 arranged to face each other in the directions X and Y. Therefore, it is possible to provide an image stabilization mechanism 3 which is more efficient, has low power consumption, does not cause resonance, and is low cost, as well as a camera module 2 and a mobile terminal 1 equipped with the same, which are superior to conventional techniques.

[0070] Although the present embodiment is as described above, the present invention is not limited to the above-mentioned form, and can be appropriately modified in design within the intended scope of the present invention. Furthermore, the effects of the present invention are not limited to those described in the above-mentioned embodiment. In other words, the embodiment disclosed this time is an example in all respects and does not limit the present invention. The scope of the present invention is defined by the claims, not the above description. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the claims.

[0071] For example, in the above embodiment, the driving wire 331 is configured to contract by generating heat by the current supplied from the power supply electrode 313. However, the present invention is not limited to this, and a heat source separate from the driving wire 331 may be provided. In this case, the power supply electrode 313 is not necessary, and both ends of the driving wire 331 are fixed to separate positions on the base 31.

[0072] In the above embodiment, both ends of the drive wire 331 are fixed to the base 31, and the middle part of the drive wire 331 is attached to the movable part 32. However, the opposite configuration may be adopted, in which both ends of the drive wire 331 are fixed to the movable part 32, and the middle part of the drive wire 331 is attached to the base 31.

[0073] Further, although the wire bend portion 322 in the above embodiment is a cylindrical protrusion, it may also be implemented as a pulley that rotates as the drive wire 331 expands and contracts.

[0074] Also, in the above embodiment, four drive wires 331 were used. However, the number of drive wires 331 in the image stabilization mechanism 3 is not limited. Therefore, three, five or more may be used. Note that it is preferable to arrange each of the multiple drive wires 331 in rotationally symmetrical positions in order to facilitate control.

[0075] Further, a groove through which the driving wire 331 passes may be formed in the wire guides 315, 325, and the driving wire 331 may be positioned relative to the wire guides 315, 325 by using this groove. [Explanation of symbols]

[0076] 1. Mobile devices 2 Camera module 3. Anti-shake mechanism 31 Base 311 Base plate (base) 312 Flexible Printed Circuit (FPC) 313 Power supply electrode 314 Magnetic material 315 Wire Guide 316 Hall element 32 Moving parts 32a Movable mechanism part 32b Imaging section 32b1 Image sensor 321 Base plate (movable part) 322 Wire bend 323 Rotating Part 324 Permanent Magnets 33 Drive unit 331 Drive Wire X 1st direction Y Second direction

Claims

1. An image stabilization mechanism built into a camera module, A base and a movable part provided on the base to face the camera module in an optical axis direction, the movable part being supported movably in a first direction perpendicular to the optical axis direction and a second direction perpendicular to the optical axis direction and the first direction relative to the base; a drive unit that connects the base unit and the movable unit and generates a drive force for moving the movable unit in at least one of the first direction and the second direction, the movable portion includes an imaging element; the driving unit has a pair of driving wires facing each other in the first direction and a pair of driving wires facing each other in the second direction, Both ends of the drive wire are fixed to the base, and an intermediate portion of the drive wire is attached to the movable portion, A camera shake prevention mechanism that moves the movable part in a direction approaching both ends of the drive wires by deforming at least one of the drive wires in a longitudinal direction.

2. The image stabilization mechanism according to claim 1 , wherein the drive wire is contracted in the length direction by being heated.

3. 3. The image stabilization mechanism according to claim 1, wherein when one of the pair of drive wires contracts, the other of the pair of drive wires expands.

4. 4. The image stabilization mechanism according to claim 1, wherein the drive wire is made of a shape memory alloy.

5. the base portion includes a power supply electrode, and both ends of the drive wire are fixed to the power supply electrode and thereby fixed to the base portion and are electrically connected to the power supply electrode; 5. The image stabilization mechanism according to claim 2, wherein the drive wire is heated by energization, thereby causing the drive wire to contract.

6. The movable portion has a rectangular shape when viewed in the optical axis direction, The movable portion includes wire bends at four corners, the bends protruding toward the base portion. The image stabilization mechanism according to any one of claims 1 to 5, wherein the intermediate portion of the drive wire abuts against a side surface of the wire bend portion, thereby attaching the intermediate portion of the drive wire to the movable portion.

7. The image stabilization mechanism according to claim 6 , wherein the wire bend portion has a groove or a protrusion that restricts the drive wire from shifting in the optical axis direction.

8. the pair of driving wires opposed to each other in the first direction are disposed symmetrically in the first direction, The pair of driving wires opposed to each other in the second direction are disposed symmetrically in the second direction, The image stabilization mechanism according to any one of claims 1 to 7, wherein a center of the imaging element as viewed in the optical axis direction coincides with a central position of the pair of driving wires opposing each other in the first direction and the pair of driving wires opposing each other in the second direction.

9. a vibration detection unit that detects vibrations applied to the camera module; 9. The image stabilization mechanism according to claim 1, further comprising: a control unit that performs control in response to the vibration detected by the vibration detection unit.

10. 10. The image stabilization mechanism according to claim 9, wherein the control unit causes the drive unit to input energy for deforming the drive wire in accordance with a magnitude of the vibration detected by the vibration detection unit, and stops the input of the energy when the vibration detection unit no longer detects vibration.

11. one of the base and the movable part includes a permanent magnet, and the other includes a Hall element; 11. The image stabilization mechanism according to claim 1, wherein the Hall element detects a positional relationship of the movable portion with respect to the base portion in at least one of the first direction and the second direction.

12. A camera module incorporating the image stabilization mechanism according to any one of claims 1 to 11.

13. A mobile terminal comprising the camera module according to claim 12.

Images