JP5105080B2 - Lens drive device - Google Patents

Description

  The present invention relates to a lens driving device, and more particularly to an autofocus lens driving device used for a portable small camera.

  A portable small camera is mounted on a camera-equipped mobile phone. This portable small camera uses an autofocus lens driving device. Conventionally, various autofocus lens driving devices have been proposed.

  For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2007-72271) can reduce the leakage of magnetic flux from a magnet that applies a magnetic field to a driving coil, thereby improving the driving efficiency of the lens holder, and also due to the leakage of magnetic flux. Disclosed is a lens driving device that can reduce adverse effects on other devices. The lens driving device disclosed in Patent Document 1 is provided with a holder for holding a lens, an annular driving coil attached to the holder, a yoke provided on the fixed member side, and an inner surface side of the yoke. And an upper spring member and a lower spring member for connecting the holder and the fixing member on the upper side which is the opening side of the lens and the lower side opposite to the opening side, respectively. The yoke includes a cylindrical upper yoke having a U-shaped cross section made of a magnetic material such as soft iron and a cylindrical lower yoke having a L-shaped cross section.

  In Patent Document 1, the yoke is supported by the fixing member and covered by the fixing member. The upper spring member and the lower spring member are provided between the yoke and the fixing member. In other words, the upper spring member and the lower spring member are disposed outside the yoke.

JP 2007-72271 A (FIGS. 1 and 2)

  In the lens driving device disclosed in Patent Document 1 described above, a fixing member for covering the yoke is required, which increases the number of components. Further, since the yoke is covered with the fixing member, there is a problem that the yoke becomes large.

  An object of the present invention is to provide a lens driving device capable of reducing the number of parts.

  Another object of the present invention is to provide a lens driving device that can be miniaturized.

  Other objects of the invention will become apparent as the description proceeds.

According to the first aspect of the present invention , the lens holder (14) having the cylindrical portion (140) for holding the lens assembly is fixed to the lens holder so as to be positioned around the cylindrical portion. The drive coil (16), the permanent magnet (18) facing the drive coil, the outer yoke ( 20 ) having a permanent magnet on the inner wall, and the optical axis (O) direction on both sides of the cylindrical portion of the lens holder. An upper elastic member (22) and a lower elastic member (24), which are provided so as to be displaceable in the optical axis (O) direction with the lens holder positioned in the radial direction. Each of the members has an inner peripheral end (222; 242) attached to the lens holder (14) and an outer peripheral end (224; 244) attached to the outer yoke (20; 20A). Energize the drive coil (16) Thus, the lens driving device (10) capable of adjusting the position of the lens holder (14) in the direction of the optical axis (O) by the interaction between the magnetic field of the permanent magnet (18) and the magnetic field generated by the current flowing through the driving coil (16). in the lower elastic member (24) and the upper elastic member (22) is disposed inside the outer yoke (20), an outer yoke (20) includes an outer tubular portion with a permanent magnet on the inner wall (202) And an outer ring end portion (204) provided at the upper end of the outer cylinder portion. The outer ring end portion (204) has an opening (204a) concentric with the optical axis (O), and an outer yoke (204). 20) is provided with a holding member for holding the outer peripheral side end portion (204) of the upper elastic member (22), and this holding member is recessed inward from the upper end corner portion of the outer yoke (20). and a recess (206) I Lens driving device is obtained characterized by and.

In the lens driving apparatus (10) according to the first aspect of the present invention, the opening (204a), it is not preferable is a minimum diameter of hole indexing from angle required by the camera module.

According to the second aspect of the present invention, the lens holder (14) having the cylindrical portion (140) for holding the lens assembly and the lens holder are fixed so as to be positioned around the cylindrical portion. Drive coil (16), permanent magnet (18) facing the drive coil, outer yoke (20; 20A) having a permanent magnet on the inner wall, and the optical axis (O) direction of the cylindrical portion of the lens holder An upper elastic member (22) and a lower elastic member (24) which are provided on both sides and support the lens holder so as to be displaceable in the optical axis (O) direction with the lens holder positioned in the radial direction. Each of the side elastic members has an inner peripheral end (222; 242) attached to the lens holder (14) and an outer peripheral end (224; 244) attached to the outer yoke (20; 20A). Through the drive coil (16) Thus, the lens driving device (10) capable of adjusting the position of the lens holder (14) in the direction of the optical axis (O) by the interaction between the magnetic field of the permanent magnet (18) and the magnetic field due to the current flowing through the driving coil (16). ), The upper elastic member (22) and the lower elastic member (24) are disposed inside the outer yoke (20; 20A), and the outer yoke (20; 20A) is an outer member provided with a permanent magnet on the inner wall. It is comprised from a cylinder part (202; 202A) and the outer ring end part (204; 204A) provided in the upper end of this outer cylinder part, and an outer ring end part (204; 204A) is concentric with an optical axis (O). It has an opening (204a) of the outer peripheral side end portion of the lower elastic member (24) to (244), further possess an inner yoke (30) for fixing over the spacer (28), an inner yoke (30 ), the outer side yoke ( 0; inner ring end attached at the lower end to the inner wall of the outer tube portion (202) of 20A) and (302), extends inside the inner ring edge portion, the parallel vertically upwards and the optical axis (O) The drive coil (16) is disposed between the plurality of vertical extensions (304) of the inner yoke (30) and the permanent magnet (18). Thus, a lens driving device can be obtained.
In the lens driving device according to the second aspect of the present invention, the plurality of vertical extending portions (304) include an outer peripheral end (244) and an inner peripheral end (242) of the lower elastic member (24). It extends vertically upward through a gap between the two. The outer yoke (20; 20A) may be provided with a holding member for holding the outer peripheral end (204) of the upper elastic member (22). For example, the holding member may include a spacer (34) provided at an inner wall corner of the outer yoke (20A).

  The reference numerals in the parentheses are given for ease of understanding, and are merely examples, and of course are not limited thereto.

  In the present invention, since the upper elastic member and the lower elastic member are arranged inside the outer yoke, the number of parts can be reduced and the size can be reduced.

  Embodiments of the present invention will be described below with reference to the drawings.

  A lens driving device 10 according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3. 1 is an external perspective view of the lens driving device 10, FIG. 2 is a cross-sectional perspective view of the lens driving device 10, and FIG. 3 is an exploded perspective view of the lens driving device 10. Here, as shown in FIGS. 1 to 3, an orthogonal coordinate system (X, Y, Z) is used. In the state shown in FIGS. 1 to 3, in the orthogonal coordinate system (X, Y, Z), the X axis is the front-rear direction (depth direction), the Y axis is the left-right direction (width direction), and the Z axis is The vertical direction (height direction). In the example shown in FIGS. 1 to 3, the vertical direction Z is the optical axis O direction of the lens.

  However, in the actual use situation, the optical axis O direction, that is, the Z-axis direction is the front-rear direction. In other words, the upward direction of the Z axis is the forward direction, and the downward direction of the Z axis is the backward direction.

  The illustrated lens driving device 10 is provided in a camera-equipped mobile phone capable of autofocusing. The lens driving device 10 is for moving a lens assembly (barrel) (not shown) in the direction of the optical axis O. The lens driving device 10 includes an actuator base 12 disposed on the lower side (rear side) in the Z-axis direction (optical axis O direction). Although not shown, an imaging element arranged on a substrate is mounted on the lower part (rear part) of the actuator base 12. The image sensor picks up a subject image formed by the lens assembly and converts it into an electrical signal. The imaging device is configured by, for example, a CCD (charge coupled device) type image sensor, a CMOS (complementary metal oxide semiconductor) type image sensor, or the like. Therefore, a camera module is configured by a combination of the lens driving device 10, the substrate, and the image sensor.

  The lens driving device 10 includes a lens holder 14 having a cylindrical portion 140 for holding a lens assembly (barrel), and a driving coil 16 fixed to the lens holder 14 so as to be positioned around the cylindrical portion 140. A pair of elastic members provided on both sides of the cylindrical portion 140 of the lens holder 14 in the optical axis O direction, the permanent magnet 18 facing the drive coil 16, the outer yoke 20 having the permanent magnet 18 on the inner wall surface, and the cylindrical portion 140 of the lens holder 14. 22 and 24. The combination of the lens assembly and the lens holder 14 is called a lens body.

  The pair of elastic members 22 and 24 support the lens holder 14 so as to be displaceable in the direction of the optical axis O in a state where the lens holder 14 is positioned in the radial direction. Of the pair of elastic members 22, 24, one elastic member 22 is called an upper elastic member, and the other elastic member 24 is called a lower elastic member. The illustrated elastic member is constituted by a leaf spring. Therefore, the upper elastic member 22 is also called an upper leaf spring, and the lower elastic member spring 24 is also called a lower leaf spring.

  Further, as described above, in the actual use situation, the upward direction in the Z-axis direction (optical axis O direction) is the forward direction, and the downward direction in the Z-axis direction (optical axis O direction) is the backward direction. Therefore, the upper elastic member (upper leaf spring) 22 is also called a front spring, and the lower elastic member (lower leaf spring) 24 is also called a rear spring.

  The illustrated outer yoke 20 has a rectangular tube shape. Therefore, the illustrated drive coil 16 also has a substantially rectangular tube shape that matches the shape of the rectangular tube-shaped outer yoke 20. The permanent magnet 18 is composed of four rectangular permanent magnet pieces 182 disposed at each corner of the square cylinder of the yoke 20.

  The outer yoke 20 includes a rectangular tubular outer tube portion 202 and a rectangular outer ring end portion 204 provided at the upper end (front end) of the outer tube portion 202. The permanent magnet is provided on the inner wall of the outer cylindrical portion 202. The outer ring end 204 has a circular opening 204a having a center concentric with the optical axis O. Further, the outer yoke 20 has four concave portions (stepped portions) 206 recessed inward at the four corners of the upper end (front end) thereof. These four concave portions (stepped portions) 206 sandwich the outer peripheral side end 224 (described later) of the upper elastic member 22 between the upper end of the permanent magnet 18 and the outer peripheral side end 224 of the upper elastic member 22. It is for holding and fixing. That is, these four concave portions (stepped portions) 206 act as holding members that hold the outer peripheral side end portion 224 of the upper elastic member 22.

  As shown in FIG. 2, the permanent magnet 18 is disposed on the inner peripheral surface of the outer cylindrical portion 202 of the outer yoke 20 at a distance from the drive coil 16.

  The upper elastic member (upper leaf spring, front spring) 22 is disposed on the upper side (front side) in the optical axis O direction of the lens holder 14, and the lower elastic member (lower leaf spring, rear spring) 24 is the optical axis of the lens holder 14. It arrange | positions at the O direction lower end (rear side). The upper elastic member (upper leaf spring, front spring) 22 and the lower elastic member (lower leaf spring, rear spring) 24 have substantially the same configuration.

  The upper elastic member (upper leaf spring, front spring) 22 includes an inner peripheral end 222 attached to the lens holder 14, an outer peripheral end 224 attached to the outer yoke 20, and an inner peripheral end 222. It has four arm parts (not shown) provided along the circumferential direction in order to connect between the outer peripheral side end part 224. The inner peripheral end 222 has an annular shape. The outer peripheral end 224 is provided apart from the inner peripheral end 222 and has a larger square ring shape than the inner peripheral end 222. Each arm portion extends along the circumferential direction.

Similarly, the lower elastic member (lower leaf spring, rear spring) 24 includes an inner peripheral end 242 attached to the lens holder 14, an outer peripheral end 244 attached to the outer yoke 20, and an inner peripheral In order to connect between the side end portion 242 and the outer peripheral side end portion 244, there are four arm portions (not shown) provided along the circumferential direction. The inner peripheral side end 242 has an annular shape. The outer end portion 244 is apart from the inner peripheral end 242, has a large quadrangular ring than the inner peripheral end 242. Each arm portion extends along the circumferential direction.

  The inner peripheral side end portions 222 and 242 are also called inner rings, and the outer peripheral side end portions 224 and 244 are also called outer rings.

  An inner peripheral end 222 of the upper elastic member (upper leaf spring, front spring) 22 is sandwiched and fixed between the lens holder 14 and the stopper 26. In other words, the stopper 26 is fitted to the lens holder 14 so as to sandwich the inner peripheral end 222 of the upper elastic member (upper leaf spring, front spring) 22 with the lens holder 14. On the other hand, the outer peripheral end 224 of the upper elastic member (upper leaf spring, front spring) 22 is sandwiched and fixed between the four recesses (steps) 206 of the outer yoke 20 and the upper end of the permanent magnet 18. .

  The stopper 26 has the following functions. That is, the stopper 26 has a function of closely contacting the inner peripheral end 222 of the upper elastic member (upper leaf spring, front spring) 22 to the lens holder 14 with high accuracy. As a result, variations in VCM (voice coil motor) characteristics can be improved. The stopper 26 has a function of improving the adhesive strength of the upper elastic member (upper leaf spring, front spring) 22. Thereby, the impact resistance of the lens driving device 10 is improved. Further, the stopper 26 has a function of preventing deformation of the upper elastic member (upper leaf spring, front spring) 22 when the lens driving device 10 is dropped. This also improves the impact resistance of the lens driving device 10.

  On the other hand, the outer peripheral end 244 of the lower elastic member (lower leaf spring, rear spring) 24 is fixed to the inner yoke 30 via the spacer 28. In other words, the spacer 28 and the outer peripheral end 244 of the lower elastic member (lower leaf spring, rear spring) 24 are sandwiched and fixed between the inner yoke 30 and the lower end of the permanent magnet 18. . An inner peripheral end 242 of the lower elastic member (lower leaf spring, rear spring) 24 is fixed to the lower end (rear end) side of the lens holder 14 with resin adhesive force.

  By energizing the drive coil 16, the position of the lens holder 14 (lens assembly) can be adjusted in the direction of the optical axis O by the interaction between the magnetic field of the permanent magnet 18 and the magnetic field generated by the current flowing through the drive coil 16. is there.

  The inner yoke 30 includes a rectangular annular inner ring end 302 attached to the inner wall of the outer cylindrical portion 202 of the outer yoke 20 at the lower end, and parallel to the optical axis O inside the four corners of the inner ring end 302. And four vertically extending portions 304 extending vertically upward.

  An inner ring end 302 of the inner yoke 30 is mounted on the actuator base 12, a spacer 28 is mounted on the inner ring end 302 of the inner yoke 30, and a lower elastic member (lower leaf spring, A rear end 244 of the rear spring 24 is mounted. The four vertically extending portions 304 of the inner yoke 30 are connected to each other via a gap between the outer peripheral end 244 and the inner peripheral end 242 of the lower elastic member (lower leaf spring, rear spring) 24. , Extending vertically upwards.

  As shown in FIG. 2, an annular cushioning material 32 is fixed to the inner wall of the outer ring end portion 204 of the outer yoke 20. The cushioning material 32 is concentric with the circular opening 204 a of the outer ring end 204. The cushioning material 32 has an outer diameter larger than the diameter of the circular opening 204a and an inner diameter smaller than the diameter of the circular opening 204a.

  As described above, the upper elastic member 22 and the lower elastic member 24 are accommodated in the outer yoke 10. Therefore, a fixing member for fixing the elastic member (spring member) outside the yoke, which is necessary in the conventional lens driving device as disclosed in Patent Document 1, is not necessary.

  More specifically, in a conventional lens driving device, a spring member (elastic member) is disposed outside the yoke. Therefore, a fixing member for fixing the spring member (elastic member) is required outside the yoke. On the other hand, the lens driving device 20 according to the present embodiment accommodates the upper elastic member 22 and the lower elastic member 24 inside the outer yoke 10, so that a fixing member (cover) that covers the outer yoke is not necessary. It becomes. Further, since no fixing member (cover) is required, the number of parts can be reduced, and the lens driving device 20 can be downsized.

  The permanent magnet 18, the outer yoke 20, and the inner yoke 30 constitute a magnetic circuit. In the outer yoke 20, the outer ring end portion 204 forms a surface on the optical axis O objective side, and the outer tube portion 202 forms a side surface. That is, the surface and side surfaces on the optical axis O objective side are formed by the outer yoke 20 made of a ferromagnetic material that is a part of the magnetic circuit and has shielding performance. A circular opening 204a formed in the outer ring end portion 204 is a hole having the smallest diameter determined from the angle of view required for the camera module. Thus, since the external appearance of the lens driving device 20 according to the present embodiment is covered with the outer yoke 20, it is excellent in dust resistance. Further, in the present embodiment, an inner yoke 30 as a ferromagnetic component is provided separately from the outer yoke 20. The drive coil 16 is disposed in a space between the four vertically extending portions 304 of the inner yoke 30 and the permanent magnet 18.

  As shown in FIG. 4, in order to hold and fix the outer peripheral end 224 of the upper elastic member 22, the outer yoke 20 includes a concave portion (stepped portion) 206. Therefore, the shape of the outer yoke 20 is complicated.

  Therefore, instead of the outer yoke 20 having a complicated shape, an outer yoke 20A having no concave portion (stepped portion) 206 as shown in FIG. 5 may be used. The outer yoke 20A shown in FIG. 5 has a square cylindrical outer cylinder portion 202A and a rectangular outer ring end portion 204A provided at the upper end (front end) of the outer cylindrical portion 202A. The outer ring end portion 204A has a circular opening 204a having a center concentric with the optical axis O.

  The outer yoke 20A does not have a concave portion (stepped portion) 206 as shown in FIG. Instead, an annular spacer 34 as shown in FIG. 5 is provided at the corner of the inner wall of the outer yoke 20A. Accordingly, the outer peripheral end 224 of the upper elastic member 22 is held and fixed to the annular spacer 34. The spacers 34 are not limited to an annular shape, and may be provided at a plurality of locations.

  Although the present invention has been described with reference to preferred embodiments, it is obvious that various modifications can be made by those skilled in the art without departing from the spirit of the present invention. For example, the actuator base 12 may be covered with an outer yoke.

1 is an external perspective view of a lens driving device according to a first embodiment of the present invention. It is a cross-sectional perspective view of the lens drive device shown in FIG. It is a disassembled perspective view of the lens drive device shown in FIG. It is sectional drawing which expands and shows only the left half of the outer yoke and upper side elastic member used for the lens drive device shown in FIG. It is sectional drawing which expands and shows only the outer half and the left half of an upper elastic member used for the lens drive device by the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Lens drive device 12 Actuator base 14 Lens holder 140 Cylindrical part 16 Drive coil 18 Permanent magnet 20, 20A Outer yoke 202, 202A Outer cylinder part 204, 204A Outer ring edge part 204a Circular opening 206 Recessed part (step part)
22 Upper elastic member 222 Inner peripheral side end (inner ring)
224 Outer end (outer ring)
24 Lower elastic member 242 Inner circumferential end (inner ring)
244 Outer end (outer ring)
26 Stopper 28 Spacer 30 Inner yoke 302 Inner ring end 304 Vertically extending portion 32 Buffer material 34 Spacer O Optical axis

Claims (10)

A lens holder having a cylindrical portion for holding the lens assembly, a drive coil fixed to the lens holder so as to be positioned around the cylindrical portion, a permanent magnet facing the drive coil, and an inner wall The upper elastic member is provided on both sides of the cylindrical portion of the lens holder in the optical axis direction, and supports the lens holder so that the lens holder can be displaced in the optical axis direction while being positioned in the radial direction. Each of the upper elastic member and the lower elastic member has an inner peripheral end attached to the lens holder and an outer peripheral end attached to the outer yoke. Then, when the drive coil is energized, a lens drive capable of adjusting the position of the lens holder in the optical axis direction due to the interaction between the magnetic field of the permanent magnet and the magnetic field generated by the current flowing through the drive coil. In the device,
The upper elastic member and the lower elastic member are disposed inside the outer yoke ,
The outer yoke has an outer cylinder portion having the permanent magnet on an inner wall, and an outer ring end portion provided at an upper end of the outer cylinder portion, and the outer ring end portion has an opening concentric with the optical axis. Have
The outer yoke is provided with a holding member for holding the outer peripheral side end of the upper elastic member,
The lens driving device according to claim 1, wherein the holding member includes a concave portion recessed inward from an upper end corner portion of the outer yoke . The lens driving device according to claim 1 , wherein the opening is a hole having a minimum diameter determined from an angle of view required for the camera module. The lens driving device according to claim 1 , further comprising an inner yoke for fixing the outer peripheral side end portion of the lower elastic member via a spacer. The inner yoke
An inner ring end attached at the lower end to the inner wall of the outer tube portion of the outer yoke;
A plurality of vertically extending portions extending vertically upward in parallel with the optical axis inside the inner ring end;
The lens driving device according to claim 3 , comprising: The lens driving device according to claim 4 , wherein the driving coil is disposed between the plurality of vertically extending portions of the inner yoke and the permanent magnet. It said plurality of vertical extending portion through a gap between said outer end portion of the lower elastic member the inner peripheral end portion, extends vertically upward in claim 5 The lens driving device described. A lens holder having a cylindrical portion for holding the lens assembly, a drive coil fixed to the lens holder so as to be positioned around the cylindrical portion, a permanent magnet facing the drive coil, and an inner wall The upper elastic member is provided on both sides of the cylindrical portion of the lens holder in the optical axis direction, and supports the lens holder so that the lens holder can be displaced in the optical axis direction while being positioned in the radial direction. Each of the upper elastic member and the lower elastic member has an inner peripheral end attached to the lens holder and an outer peripheral end attached to the outer yoke. Then, when the drive coil is energized, a lens drive capable of adjusting the position of the lens holder in the optical axis direction due to the interaction between the magnetic field of the permanent magnet and the magnetic field generated by the current flowing through the drive coil. In the device,
The upper elastic member and the lower elastic member are disposed inside the outer yoke,
The outer yoke has an outer cylinder portion having the permanent magnet on an inner wall, and an outer ring end portion provided at an upper end of the outer cylinder portion, and the outer ring end portion has an opening concentric with the optical axis. Have
An inner yoke for fixing the outer peripheral side end of the lower elastic member via a spacer;
The inner yoke
An inner ring end attached at the lower end to the inner wall of the outer tube portion of the outer yoke;
A plurality of vertically extending portions extending vertically upward in parallel with the optical axis inside the inner ring end;
Consists of
Lens driving device, characterized in that said drive coil is arranged between said plurality of said permanent magnet and vertical extending portion of the inner yoke. It said plurality of vertical extending portion through a gap between said outer end portion of the lower elastic member the inner peripheral end portion, extends vertically upward in claim 7 The lens driving device described. The lens driving device according to claim 7, wherein the outer yoke is provided with a holding member for holding the outer peripheral side end of the upper elastic member. The lens driving device according to claim 9 , wherein the holding member includes a spacer provided at an inner wall corner of the outer yoke.

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