JP7701385B2 - Anti-shake mechanism, camera module, mobile terminal - Google Patents

Description

The present invention relates to an image stabilization mechanism built into a camera module of a device such as a mobile terminal (e.g., a smartphone or tablet), and to a camera module and a mobile terminal equipped with the same.

An example of prior art related to the present invention is the optical image stabilization (OIS) mechanism described in CN108780207A.

In this prior art, a dynamic platform equipped 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 voice coil motor frame 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.

The voice coil motor used as the driving source in this configuration has low efficiency and consumes a lot of power. In addition, the combination of a dynamic platform and a static platform in this configuration has problems such as being prone to resonance, large attitude differences, and high costs.

In light of this, the present invention aims to provide an image stabilization mechanism that is superior to conventional technology, has high efficiency, consumes less power, is less susceptible to resonance, has smaller attitude differences, and is low cost, as well as a camera module and a mobile terminal that are equipped with the same.

One embodiment of the present invention is an image stabilization mechanism built into a camera module, comprising: a base; a movable part provided on the base opposite the optical axis direction of the camera module, the movable part being supported movably in each of 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 that connects the base and the movable part and generates a drive force for moving the movable part in at least one of the first direction and the second direction, the movable part having an image sensor, the drive part having 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 being fixed to the base, and an intermediate part of the drive wires being attached to the movable part, the image stabilization mechanism moving the movable part in a direction approaching both ends of the drive wires by deforming at least one of the drive wires in the length direction.

The drive wire can also be configured to shrink lengthwise when heated.

In addition, when one of the drive wires constituting the pair contracts, the other of the drive wires constituting the pair can be extended.

The drive wire can be made of metal, but can also be made of other materials that can realize the present invention, and is preferably made of a shape memory alloy.

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 can be contracted by heating itself when electricity is passed through it.

The movable part has a rectangular shape when viewed in the optical axis direction, and the movable part has wire bends at its four corners that protrude toward the base, and the intermediate part of the drive wire abuts against the side of the wire bend, thereby attaching the intermediate part of the drive wire to the movable part.

The wire bend portion may also include a groove or protrusion that prevents the drive wire from shifting in the optical axis direction.

The pair of drive wires facing each other in the first direction are arranged symmetrically in the first direction, and the pair of drive 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 can be aligned with the central positions of the pair of drive wires facing each other in the first direction and the pair of drive wires facing each other in the second direction.

The camera module may also 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.

The control unit can also cause the drive unit to input energy to deform the drive wire according to the magnitude of the vibration detected by the vibration detection unit, and can stop the input of energy when the vibration detection unit no longer detects vibration.

In addition, one of the base and the movable part may include a permanent magnet, and the other may include a Hall element, and the Hall element may detect the positional relationship of the movable part relative to the base in at least one of the first direction and the second direction.

Another aspect of the present invention is a camera module that incorporates the image stabilization mechanism.

Another aspect of the present invention is a mobile terminal equipped with the camera module.

FIG. 1 is a schematic diagram showing how to prevent camera shake in a smartphone. FIG. 2 is a schematic diagram showing the process in the image stabilization mechanism. 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. FIG. 4 shows the image stabilization mechanism, as viewed from the rear of the base plate of the movable portion. FIG. 5 is a diagram showing parts necessary for explanation extracted from FIG. FIG. 6 is a diagram showing parts necessary for explanation extracted from FIG. FIG. 7A is a side view showing an imaging section of the movable section in the image stabilization mechanism. FIG. 7B is a side view showing the base and movable portion (excluding the imaging portion) of the image stabilization mechanism. FIG. 8A is a plan view showing a base portion of the image stabilization mechanism. FIG. 8B is a right side view showing a base portion of the image stabilization mechanism. FIG. 9A is a right side view showing the movable portion (excluding the imaging element support portion) of the image stabilization mechanism. FIG. 9B is a bottom view showing the movable portion (excluding the imaging element support portion) of the image stabilization mechanism.

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).

The image stabilization mechanism 3 of this embodiment is built into a camera module 2 provided 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 the user's hand 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 shown by the arrow in Fig. 1. They may also have a linear motion component.

As shown in FIG. 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 image sensor 32b1 can be made blur-free.

Figure 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 image sensor 32b1 is provided behind the lens support section 21 in the optical axis direction, and receives imaging light that passes through the lens and forms an image. This image sensor 32b1 is provided in the image stabilization mechanism 3.

The image stabilization mechanism 3 includes a base 31, a movable part 32, and a drive part 33. The base 31 is a plate-shaped part that is 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 board (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 FIG. 8A and FIG. 8B). The base plate 311 has a square shape (specifically, a rectangle) when viewed in the optical axis direction. The part of the flexible circuit board 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-shaped current is supplied to the power supply electrode 313 from outside the image stabilization mechanism 3 in the camera module 2. The current supplied may be a direct current or a current having a waveform other than a square wave.

The movable part 32 is a plate-like part provided opposite the base part 31 in the optical axis direction. The movable part 32 includes a flat base plate 321. The base plate 321 has a quadrilateral shape (specifically, a rectangle) when viewed in the optical axis direction. As shown in Figures 7A and 7B, the movable part 32 includes a movable mechanism part 32a and an imaging part 32b that is separate from the movable mechanism part 32a and is integrated with the movable mechanism part 32a by, for example, being attached to the movable mechanism part 32a by adhesive. The imaging part 32b includes an imaging element 32b1.

The movable part 32 is supported on the base part 31 so as to be movable in 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. The movable part 32 can also move in a direction that combines the first direction X and the second direction Y (a diagonal direction in FIG. 4 at any angle).

9A and 9B, the movable part 32 has wire bends 322 at the four corners, which protrude rearward (towards 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 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 section 322 has a groove 3221 that restricts the drive 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 section 322 so as to be perpendicular to the axial direction of the cylindrical wire bend section 322. Note that a protrusion for hooking the drive wire 331 may be provided instead of the groove 3221. Alternatively, the entire outer circumferential surface of the wire bend section 322 may be curved, and the drive wire 331 may be hooked on a recessed portion of the curved surface.

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

The base 31 and the movable part 32 are held in position in the optical axis direction while allowing movement in the surface direction so as not to separate in the optical axis direction. Specifically, the position is held in the optical axis direction by the magnetic attraction between multiple (four in this embodiment) permanent magnets 324 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 in a position facing the multiple permanent magnets 324. The attraction force between the permanent magnets 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 surface direction by providing a stopper or the like that abuts against the movable part 32 to restrict movement beyond the driving range of the driving part 33.

9B, the movable part 32 is provided with a cylindrical wire guide 325 in addition to the wire bend 322. This wire guide 325 protrudes rearward from the base plate 321 of the movable part 32. The wire guide 325 is formed of an insulating material such as resin. As shown in FIG. 4 and FIG. 5, which shows a partial configuration extracted from FIG. 4, this wire guide 325 is located between the power supply electrode 313 and the wire bend 322 (the one closest to the power supply electrode 313 on the path) in the path through which each driving wire 331 passes. Each driving wire 331 (the combination of the driving wire 331 shown in FIG. 5 and the driving wire 331 (not shown) that is symmetrical to the driving wire 331 shown in FIG. 5) 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 drive wire 331 changes according to the extension and contraction of each drive 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 drive wire 331 in a direction intersecting the extension direction between the power supply electrode 313 and the wire bend part 322.

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) in the path through which each driving wire 331 passes. Each driving wire 331 of which a pair (two wires) faces 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 drive wire 331 changes according to the extension and contraction of each drive wire 331. Similar to the wire guide 325 of the movable part 32, this wire guide 315 suppresses the wobble of each drive wire 331 in a direction intersecting the extension direction between the power supply electrode 313 and the wire bend part 322.

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 anti-shake mechanism 3 in this embodiment) is equipped with a Hall element 316. As shown in Figures 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 Figure 8A) and one of a pair (two pieces) of magnetic bodies 314 extending in the second direction Y (the left magnetic body 314 in Figure 8A), and is provided so as to be sandwiched between two magnetic bodies 314 arranged in each direction. This Hall element 316 detects the 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 way, the Hall element 316 is sandwiched between two magnetic bodies 314 arranged in each direction, so that the attractive force (magnetic force) between the permanent magnet 324 and the magnetic bodies 314 can be used to hold the positions of the base 31 and the movable part 32 in the optical axis direction, and the positional relationship of the movable part 32 to the base 31 can be detected in the same area.

The driving unit 33 is a part that connects the base 31 and the movable unit 32 and generates a driving force to move 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. In other words, 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 when 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 part where the driving wires 331 cross each other as viewed in the optical axis direction and around it, as shown in FIG. 4. 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 in the optical axis direction of the image stabilization mechanism 3. 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, but for example, a diameter of 50 μm. The cross-sectional dimensions can be determined taking into consideration 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 stretches in the length direction. This stretching 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 the pair (two wires).

Both ends of the drive wire 331 (more specifically, both ends of the portion of the drive wire 331 where the 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 onto the 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 (not in a contracted or extended state) is set to a level that does not cause slack. By keeping the drive wire 331 in a tensioned free state, it is possible to ensure a quick response. The tension can be set taking into consideration the temperature changes in which the mobile terminal 1 is expected to be used.

As shown in FIG. 4, a pair (two) of drive wires 331 facing in the first direction X are arranged symmetrically in the first direction X, and a pair (two) of drive wires 331 facing in the second direction Y are arranged symmetrically in the second direction Y. The pair of drive wires 331 facing in the first direction X and the pair of drive wires 331 facing in the second direction Y are arranged so that their central positions coincide with the center of the image sensor 32b1 as viewed in the optical axis direction (the position where the diagonals intersect in a rectangle or square). By deforming at least one of the drive wires 331 (specifically, the drive wire 331 is heated and contracts), the movable part 32 can be moved in a direction approaching both ends of the drive wire 331.

In this embodiment, the driving wire 331 is heated by using resistance heat generated by passing current through the driving wire 331 itself. For this reason, 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. Of the power supply electrode 313, the side to which one end of the driving wire 331 is fixed is the positive electrode, and the side to which the other end is fixed is the 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 contracts by generating heat itself due to the current supplied from the power supply electrode 313. For this reason, in this embodiment, the driving wire 331 contracts 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 spontaneously contract or extend. 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 action in detail, one driving wire 331 that contracts due to energization transmits a driving force to the wire bending portion 322 to which the driving wire 331 is hooked. Accordingly, the movable part 32 moves. As a result, the other driving wire 331 (not energized) that is hooked to another wire bending 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 drive wires 331 is not hindered by the other of the drive wires 331. Furthermore, one of the drive wires 331 contracts while the tension of the other of the drive wires 331 is applied to the movable part 32, so the movable part 32 can be moved stably. From the outside, the pair of drive 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.

Of the pair (two) of drive wires 331 facing 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 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 of them contracts, the other does not contract, so that the contraction forces of both (two) do not oppose each other at the same time. Of the pair (two) of drive wires 331 facing the second direction Y (up-down direction in the figure), one is extracted and shown in FIG. 6 for ease of explanation. Furthermore, of the pair of drive wires 331 facing in the second direction Y, the one that is in a positional relationship facing the one shown in FIG. 6 operates 180° symmetrically in the optical axis direction with respect to the one shown in the figure (operation is upside down in the figure). Note that each of the pair of drive wires 331 facing in the second direction Y operates 90° symmetrically 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 only be given with reference to FIG. 5.

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

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 in the left direction of the arrows shown in the figure along the upper and lower paths (first path 331a and third path 331c) in the upper and lower paths (first path 331a and third path 331c), respectively. The driving wire 331 also moves in the right path (second path 331b) as the path contracts. Since the power supply electrode 313 is provided on the fixed base 31, the upper and lower wire bends 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 drive wire 331 (not shown in FIG. 5) of the pair contracts due to its own tension (it can also be contracted by passing electricity through it). As a result, 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 passed through it.

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 an equal distance along the virtual line. Therefore, the base plate 321 on which the wire bend part 322 is provided also moves the same distance.

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 in a conducting state and the other is in a non-conducting state. 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 in a conducting state and the other is in a non-conducting state. The drive wire 331 on the first direction X side and the drive wire 331 on the second direction Y side may be simultaneously energized. In this case, the movable part 32 can be moved in an oblique direction. By providing a difference in the current flowing through 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.

As a comparative example, a configuration is presented in which two diagonal points on a movable part formed into 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 drive wire made of a shape memory alloy. In this comparative example, four drive 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 it complicated to control the current (on/off) of the four drive wires.

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 the first direction X and one of a pair (two) of drive wires 331 facing the second direction Y, or by energizing only one of the pair of drive wires 331 facing the first direction X, or by energizing only one of the pair of drive wires 331 facing 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 wires 331 as the drive source, the camera shake prevention mechanism 3 can be made less susceptible to resonance than conventional mechanisms, the posture difference can be reduced, and costs can be reduced.

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. Note that 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.

By controlling the control unit while taking into consideration the time difference between the energization (input) to the drive wires 331 and the contraction (output), it is possible to improve the responsiveness to vibrations applied to the camera module 2 due to camera shake. In addition, by instantly switching between energization of one of a pair of drive wires 331 facing each other in each of the X and Y directions, the control unit can realize agile movement of the movable part 32 relative to the base 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.

To summarize the present embodiment, the present embodiment is an image stabilization mechanism 3 built into a camera module 2, comprising a base 31 and 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 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 includes an image sensor 32b1, the driving unit 33 has a pair of driving wires 331 that face the first direction X and a pair that face the second direction Y, both ends of the driving wires 331 are fixed to the base 31, and the middle portion of the driving wires 331 is attached to the movable unit 32, and the anti-shake mechanism 3 moves 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 length direction.

With this configuration, the movable part 32 equipped with the image sensor 32b1 can be moved relative to the base part 31 by deforming at least one of the pair of drive wires 331 made of shape memory alloy that are arranged to face each other in the X and Y directions.

The drive wire 331 can also be configured to shrink in the longitudinal direction when heated.

With this configuration, the contraction force of the drive wire 331 can be used to move the movable part 32 relative to the base part 31.

In addition, when one of the pair of drive wires 331 contracts, the other of the pair of drive wires 331 can be extended.

With this configuration, the driving force generated by one of the drive wires 331 is not impeded by the other drive wire 331.

The drive wire 331 may also be made of a shape memory alloy.

This configuration allows the drive wire 331 to be made from a material that is easily available.

The base 31 is provided with a power supply electrode 313, and both ends of the drive 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. The drive wire 331 can be contracted by generating heat by passing electricity through it.

With this configuration, the drive wire 331 contracts by generating heat when electricity is passed through it, so there is no need for a separate heating means for heating the drive wire 331.

The movable part 32 has a rectangular shape when viewed in the optical axis direction, and has wire bends 322 at its four corners that protrude toward the base 31. The middle part of the drive wire 331 abuts against the side of the wire bends 322, so that the middle part of the drive wire 331 is attached to the movable part 32.

With this configuration, the wire bends 322 provided at the four corners of the movable part 32 make it easy to configure a pair of drive wires 331 that face each other in the X and Y directions.

The wire bend portion 322 may also have a groove or protrusion that prevents the drive wire 331 from shifting in the optical axis direction.

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

The pair of drive wires 331 facing the first direction X are arranged symmetrically in the first direction X, and the pair of drive wires 331 facing the second direction Y are arranged symmetrically in the second direction Y, and the center of the image sensor 32b1 viewed in the optical axis direction can be aligned with the center positions of the pair of drive wires 331 facing the first direction X and the pair of drive wires 331 facing the second direction Y.

With this configuration, all of the drive wires 331 are arranged symmetrically, and the center of the image sensor 32b1 is positioned at the center of the arrangement, simplifying the configuration of the image stabilization mechanism 3.

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.

With this configuration, the control unit controls the camera in response to the vibrations detected by the vibration detection unit, resulting in a high-performance camera shake prevention mechanism 3.

The control unit can also cause the drive unit 33 to input energy to deform the drive wire 331 according to the magnitude of the vibration detected by the vibration detection unit, and can stop the input of energy when the vibration detection unit no longer detects vibration.

With this configuration, the control unit can control the energy input to the drive unit 33, resulting in a high-performance camera shake prevention mechanism 3.

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 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.

With this configuration, the combination of the permanent magnet 324 and the Hall element 316 can simplify the configuration for detecting the movement state of the movable part 32.

This embodiment also relates to a camera module 2 that incorporates the image stabilization mechanism, and a mobile terminal 1 that includes the camera module 2.

In this embodiment configured as described above, the movable part 32 equipped with the image sensor 32b1 can be moved relative to the base part 31 by a pair of drive wires 331 arranged to face each other in the X and Y directions, so that it is possible to provide an image stabilization mechanism 3 that is more efficient, consumes less power, does not cause resonance, and is low in cost, and a camera module 2 and a mobile terminal 1 equipped with the same, which are superior to conventional technology.

Although the present embodiment is as described above, the present invention is not limited to the above-mentioned form, and the design can be appropriately modified 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 here 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 that are equivalent in meaning to and within the scope of the claims.

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

In addition, 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 used, 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.

In addition, while the wire bending portion 322 in the above embodiment is a cylindrical protrusion, it can also be implemented as a pulley that rotates as the drive wire 331 expands and contracts.

In addition, 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.

In addition, a groove through which the drive wire 331 passes may be formed in the wire guides 315 and 325, and the drive wire 331 may be positioned relative to the wire guides 315 and 325 using this groove.

1 Portable terminal 2 Camera module 3 Anti-shake mechanism 31 Base 311 Base plate (base)
312 Flexible Printed Circuit (FPC)
313 Power supply electrode 314 Magnetic body 315 Wire guide 316 Hall element 32 Movable part 32a Movable mechanism part 32b Imaging part 32b1 Imaging element 321 Base plate (movable part)
322 Wire bending portion 323 Rotation portion 324 Permanent magnet 33 Driving portion 331 Driving wire X First direction Y Second direction

Claims (13)

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 portion, and an intermediate portion of the drive wire is attached to the movable portion,
At least one of the driving wires is deformed in a longitudinal direction to move the movable portion toward both ends of the driving wire ;
The movable portion is provided with two first wire guides protruding toward the base portion so as to face each other in the second direction, and each drive wire of the pair facing each other in the first direction abuts against the outer peripheral surfaces of the two first wire guides , an anti-shake mechanism. The drive wire is heated to contract in the longitudinal direction ,
When one of the pair of drive wires contracts, the other of the pair of drive wires expands,
The image stabilization mechanism according to claim 1 , wherein the drive wire is made of a shape memory alloy . 2. The image stabilization mechanism according to claim 1, wherein the base portion is provided with two second wire guides protruding toward the movable portion so as to face each other in the first direction, and each drive wire of the pair facing each other in the second direction abuts against an outer peripheral surface of the two second wire guides . 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;
3. The image stabilization mechanism according to claim 2, wherein the drive wire is heated by energization, thereby causing the drive wire to contract. 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 camera shake prevention mechanism according to claim 1 , wherein the intermediate portion of the drive wire is attached to the movable portion by abutting against a side surface of the wire bend portion. The image stabilization mechanism according to claim 5 , wherein the wire bend portion has a groove or a protrusion that restricts the drive wire from being misaligned in the optical axis direction. 6. The image stabilization mechanism of claim 5, wherein a rotating portion is provided at an axial end of the wire bend portion, the rotating portion having a rotor embedded therein so as to protrude partially from an end face of the wire bend portion facing the base portion, the rotating portion abutting against a surface of the base portion and rotating relative to the surface of the base portion. 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 claim 1 , 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. a vibration detection unit that detects vibrations applied to the camera module;
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. The image stabilization mechanism according to claim 9, wherein the control unit causes the drive unit to input energy to deform the drive wire in accordance with 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. one of the base and the movable part includes a permanent magnet, and the other includes a Hall element;
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. A camera module incorporating the image stabilization mechanism according to any one of claims 1 to 11 . A mobile terminal equipped with the camera module according to claim 12.