JP2006301058A - Lens driving device and camera module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens driving device that can improve focusing precision at a power variation position and make one of longitudinal and lateral dimensions viewed from a subject side narrower matching the diameter of a lens group. <P>SOLUTION: A zooming mechanism which synchronously moves both movable lenses 35 and 41 with the power of a first electric motor is incorporated in between the lens group of a fixed lens and both the movable lenses and one lengthwise end wall of a casing. A focusing mechanism 29 which moves one of the both the movable lenses moved by the zooming mechanism with the power of a second electric motor 81 is incorporated in between the lens group and the other lengthwise end wall of the casing 21. The movable lens 41 includes a base member 42 which has a screw shaft arrangement portion 42d, a feed screw shaft 45 which is rotatably supported by the screw shaft arrangement portion 42d and rotated by the mechanism 29, and a focus lens holder 44 which has a nut 50 to threadably engage the screw shaft, can freely move to and away from the member 42, and supports the focus lens 43. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lens driving device that is mounted on a portable electronic device such as a card-type digital camera or a camera-equipped mobile phone and performs focusing and zooming, and a camera module that includes the device.

  2. Description of the Related Art Conventionally, zoom lens apparatuses that perform zooming by moving a lens and perform focusing in the zoomed state are known (see, for example, Patent Document 1).

  The zoom lens device houses a rotating cylinder in a fixed cylinder, and includes a front group lens, a shutter block, a rear group lens moving cylinder, a rectilinear cylinder, a rear group lens frame, a drive ring, A cylindrical member such as a rectilinear guide frame is accommodated. The rotating cylinder, the rear group lens frame, the rectilinear cylinder, and the rear group lens frame are formed with a small diameter in the order of description, and are concentrically accommodated in the fixed cylinder. An idling region that allows only the drive ring to rotate within a certain range is provided in a link portion between the drive ring driven by the motor and the rotary cylinder.

  In the zoom lens device disclosed in Patent Document 1, the drive ring is displaced beyond the idling range, and the front lens group and the rear lens group are moved and zoomed as the movable cylinder is rotated. By displacing the drive ring within the region, focusing can be performed by moving only the rear lens group while the rotation of the movable cylinder is stopped.

In this case, in order to change the magnification by moving the rear group lens in the direction in which the optical axis extends, rotation of the rear group lens moving cylinder causes a plurality of cam grooves provided on the inner periphery of the moving cylinder and the rear group lens frame. The engaging position with the cam pin is changed. In addition, even when the rear lens group is moved and focused, the engagement position of the cam grooves provided on the outer periphery of the movable cylinder and the cam projection of the drive ring is changed by the rotation of the rear lens group moving cylinder. Let me go.
JP 10-133091 (paragraphs 0006-0016, FIGS. 1-6)

  In the technique described in Patent Document 1, since a large number of cylindrical members are concentrically arranged, the thicknesses of the respective cylindrical members, fitting gaps for preventing adjacent cylindrical members from competing with each other, etc. Defines the outer diameter of the fixed cylinder forming the outermost cylindrical member. As a result, the diameter of the fixed cylinder must be larger than the diameter of the rear group lens frame holding the rear group lens, and this zoom lens device has large vertical and horizontal dimensions when viewed from the subject side.

  By the way, for example, in a camera module or the like mounted on a portable device such as a camera-equipped mobile phone, one of the vertical and horizontal dimensions viewed from the subject side may be narrowed for convenience of mounting. It has been requested. However, since the technique described in Patent Document 1 is not suitable for reducing the outer diameter of the outermost fixed cylinder, the above requirement cannot be satisfied.

  In addition, the technique described in Patent Document 1 that performs zooming or focusing by changing the engagement position of the cam pin and the cam protrusion to the cam groove is a configuration in which the range in which the cam groove can be provided is limited to a small size. Under this condition, the rear lens group is moved according to the inclination angle of the cam groove with respect to the optical axis according to the rotation angle of the rear lens group moving cylinder, which is disadvantageous in increasing the focusing accuracy.

  The object of the present invention is to improve the focusing accuracy at the zoom position, and to drive the lens so that one of the vertical and horizontal dimensions viewed from the subject side can be narrowed to fit the size of the lens group. To provide an apparatus and a camera module.

  In order to solve the above-mentioned problems, a lens driving device according to the present invention includes a casing having a rectangular parallelepiped shape and having a guide member and a fixed lens attached to an intermediate position in a longitudinal direction thereof; A first movable lens that is moved in a direction in which the axis extends; a second movable lens that is built in the casing and moves in the direction in which the optical axis extends along the guide member so as to face the first movable lens. A lens; a lens group of the fixed lens and both movable lenses, and one end wall in the longitudinal direction of the casing, and is incorporated in the casing, and includes a first electric motor, and the first motor is driven by the power of the motor. A zoom mechanism that moves the second movable lens in synchronization; and is located between the lens group and the other end wall of the casing in the longitudinal direction; A focus mechanism that includes a second electric motor, and moves one of the first and second movable lenses moved by the zoom mechanism with the power of the second electric motor; One of the first and second movable lenses has a screw shaft placement portion and is moved along the guide member, and the focus mechanism is rotatably supported by the screw shaft placement portion. A focus screw holder that has a feed screw shaft that is rotated by the lens and a nut that holds the focus lens and is screwed to the feed screw shaft and is movable in the direction in which the optical axis extends with respect to the base member And.

  The lens driving device according to the present invention performs zooming by moving the first and second movable lenses in the direction in which the optical axis extends with respect to the fixed lens by the zoom mechanism, and the zoom position obtained thereby. Thus, focusing can be performed by moving the focus lens of one movable lens in the direction in which the optical axis extends by the focus mechanism. In this focusing, the feed amount of the focus lens with respect to the rotation of the feed screw shaft is finely controlled by the change in meshing between the nut provided on the focus lens holder holding the focus lens and the feed screw shaft rotated by the focus mechanism. Since it can, it can be focused with high accuracy.

  Furthermore, in the present invention, the zoom mechanism and the focus mechanism built in the casing are individually arranged and arranged on both sides of the lens group, so that the shape of the casing viewed from the subject side is one of the vertical and horizontal dimensions. Can be formed in a rectangular shape narrower than the other. In this case, since the elements of the two mechanisms are not arranged on both sides of the lens group along the direction orthogonal to the arrangement direction, both side walls extending in the longitudinal direction of the casing can be as close as possible to the lens group.

  In a preferred form of the lens driving device according to the present invention, the zoom mechanism has a cylindrical cam having a cam groove on a peripheral surface and extending in a direction in which the optical axis extends, and the first electric motor for rotating the cam. And a cam follower provided on each of the base member and the other movable lens with respect to the one movable lens is engaged with the cam groove.

  In the embodiment of the present invention, when the cam is driven to rotate, the engaging position of the cam groove and the cam follower is changed to move both the movable lenses to the zooming position synchronously. It is suitable for coarse movement of both movable lenses to the zoom position quickly according to the above. In addition, since there is no particular restriction on increasing the lead angle of the cam groove provided spirally along the circumferential surface of the cylindrical cam, the maximum swaying dimension of the movable lens can be secured large, thereby making a large change. Suitable for obtaining double performance.

  In a preferred form of the lens driving device according to the present invention, the focus mechanism includes a drive shaft having a gear portion extending in a direction in which the optical axis extends longer than a maximum zoom dimension by the zoom mechanism, and the first shaft that rotates the drive shaft. An input gear that includes two electric motors and that is slidably engaged with the gear portion along the axial direction of the drive shaft is provided on the feed screw shaft.

  In the embodiment of the present invention, the input gear of the feed screw shaft that is moved at the same time as the movable lens is moved to the zooming position by the zoom mechanism slides on the gear portion along the axial direction of the drive shaft. The focusing operation by the focus mechanism at the zoom position can be realized while maintaining the meshing with the gear portion.

In order to solve the above-mentioned problems, a lens driving device of the present invention has a rectangular parallelepiped shape, a casing having a guide member and a fixed lens attached at an intermediate position in the longitudinal direction thereof, and a first cam follower. A first movable lens built in the casing and moved in a direction in which the optical axis extends along the guide member; and has a second cam follower and is built in the casing so as to face the first movable lens A second movable lens that is moved in a direction in which the optical axis extends along the guide member; and is positioned between the fixed lens and the lens group of both movable lenses and one end wall in the longitudinal direction of the casing. A cam that is built in the casing and has a cam groove that engages with the first and second cam followers on its peripheral surface and extends in the direction in which the optical axis extends, and a first electric motor that rotates the cam With A zoom mechanism for moving the first and second lenses in synchronism; a maximum zoom by the zoom mechanism, located between the lens and the other end wall in the longitudinal direction of the casing; A drive shaft having a gear portion extending in a direction in which the optical axis extends longer than the dimension, and a focus mechanism including a second electric motor for rotating the drive shaft, and the first and second lenses. A base member that is moved along the guide member with one of the first and second cam followers and a screw shaft arrangement portion disposed near the drive shaft; A feed screw shaft having an input gear slidably engaged with the gear portion along the axial direction of the drive shaft and rotatably supported by the screw shaft arrangement portion; and holding the focus lens and the feed screw Threaded onto the shaft The focus lens holder provided movably in a direction in which the optical axis extends relative to said base member has a nut,
It has.

  The lens driving device of the present invention drives the first electric motor of the zoom mechanism to rotate the cam, and changes the engagement position between the cam and the cam followers of the first and second movable lenses. The zooming can be performed by moving the first and second movable lenses in the direction in which the optical axis extends with respect to the fixed lens. Thereafter, at the zoom position obtained by zooming, the second electric motor of the focus mechanism is driven to rotate the drive shaft so that the feed screw shaft and the focus lens holder nut engaged with the feed screw shaft mesh with each other. By changing the position, focusing can be performed by moving the focus lens of one movable lens in the direction in which the optical axis extends. In this focusing, the feed amount of the focus lens with respect to the rotation of the feed screw shaft is finely controlled by the change in meshing between the nut provided on the focus lens holder holding the focus lens and the feed screw shaft rotated by the focus mechanism. Since it can, it can be focused with high accuracy.

  Furthermore, in the present invention, the zoom mechanism and the focus mechanism built in the casing are individually arranged and arranged on both sides of the lens group, so that the shape of the casing viewed from the subject side is one of the vertical and horizontal dimensions. Can be formed in a rectangular shape narrower than the other. In this case, since the elements of the two mechanisms are not arranged on both sides of the lens group along the direction orthogonal to the arrangement direction, both side walls extending in the longitudinal direction of the casing can be as close as possible to the lens group.

  In a preferred embodiment of the lens driving device according to the present invention, a guide hole is provided in the base member, a sliding part positioned around the focus lens is provided in the focus lens holder, and the sliding part is slid into the guide hole. It fits freely.

  In the embodiment of the present invention, the sliding between the guide hole and the sliding portion can reduce the concentration of the weight of the focus lens holder and the focus lens on the threaded portion between the feed screw shaft and the nut. Therefore, the focusing operation is smoothed and the durability of the screwing portion can be improved.

  In a preferred embodiment of the lens driving device of the present invention, the focus lens holder is provided with a plurality of sliding holes that are slidably fitted into the guide member.

  Even in the embodiment of the present invention, it is possible to reduce the concentration of the weight of the focus lens holder, the focus lens, etc. on the threaded portion between the feed screw shaft and the nut. The durability of the part can be improved.

  In order to solve the above problem, a camera module of the present invention includes a lens driving device according to any one of claims 1 to 6; and an image pickup disposed on an optical axis of the lens driving device. And a control unit that controls the zoom mechanism included in the lens driving device to perform zooming, and controls the focus mechanism included in the lens driving device to execute focusing.

  Since the present invention includes any one of the lens driving devices described above, it is possible to improve the focusing accuracy at the zoom position by obtaining the above-described action, and to obtain the vertical and horizontal directions viewed from the subject side. Thus, a camera module can be provided in which one of the above dimensions can be narrowed in conformity with the diameter of the lens group.

  According to the present invention, it is possible to improve the focusing accuracy at the zooming position, and at the same time, a lens drive that can be narrowed by adapting one of the vertical and horizontal dimensions viewed from the subject side to the size of the lens group diameter. Devices and camera modules can be provided.

  An embodiment of the present invention will be described with reference to FIGS.

  Reference numeral 11 in FIG. 5 denotes a camera module. The camera module 11 is mounted on a printed wiring board in the body of a thin portable electronic device such as a mobile phone with a camera. The camera module 11 includes a lens driving device 12, a circuit block 13, an image sensor 14 and the like.

  The lens driving device 12 includes a rectangular parallelepiped casing 21 as viewed from the subject side, a plurality of guide members such as a first guide shaft 25 and a second guide shaft 26, and a plurality of groups such as a four-group configuration. Lens, a zoom mechanism 28, a focus mechanism 29, and the like.

  As shown in FIGS. 1 to 4, the casing 21 has a rectangular base shape 22 as viewed from the object side, a rectangular parallelepiped box shape corresponding to the base 22, and the back surface is open. The cover 23 is connected to the cover 23. The base 22 is disposed so as to close the back opening of the cover 23. The base 22 and the cover 23 are made of hard synthetic resin.

  A substantially central portion in the longitudinal direction of the front wall 23a of the cover 23 positioned so as to face the base 22 is opened, and a female screw is formed on the inner peripheral surface of the opening edge 23b. The front wall 23a is formed with a lens holder portion 24 that protrudes from the back surface thereof and that is continuous with the opening edge portion 23b.

  One end of each of the first guide shaft 25 and the second guide shaft 26 made of a metal round bar is press-fitted into the mounting hole 22a of the base 22, and the other end is press-fitted into the mounting hole 23c of the cover 23. The base 22 and the front wall 23a of the cover 23 are fixed. The first guide shaft 25 and the second guide shaft 26 are provided in parallel with the optical axis O of the four-group lens, with a four-group lens disposed between them.

  As shown in FIG. 1, one guide shaft, for example, the first guide shaft 25 is arranged close to one side wall 21 a extending in the longitudinal direction of the casing 21 formed mainly on one of the long side walls of the cover 23, and the other side. The second guide shaft 26, for example, the second guide shaft 26 is arranged close to the other side wall 21 b extending in the longitudinal direction of the casing 21 formed mainly on the other of the long side walls of the cover 23. That is, the first guide shaft 25 and the second guide shaft 26 are arranged so that a straight line connecting them is obliquely intersected with the longitudinal direction of the casing 21. Accordingly, the first guide shaft 25 and the second guide shaft 26 are prevented from being prevented as much as possible from disposing the zoom mechanism 28 or the focus mechanism 29 closer to the four-group lens.

  In the lens holder portion 24 of the cover 23, the first fixed lens 31 forming the first group lens as viewed from the subject side, in other words, viewed from the light incident direction, closes the opening of the front wall 23a. Opposed and fixed. The first fixed lens 31 is sandwiched between a ring-shaped lens retainer 34 screwed into the female screw of the opening edge 23 b and the annular lens receiving portion 24 a of the lens holder portion 24. The first fixed lens 31 and the lens retainer 34 are bonded to the cover 23 using an adhesive if necessary.

  A second fixed lens 33 that forms a fourth group lens as viewed from the light incident direction is fixed to a substantially central portion in the longitudinal direction of the base 22 in correspondence with the first fixed lens 31. Each of the second fixed lens 33 and the first fixed lens 31 is formed of a single lens element or a plurality of lens elements combined.

  As shown in FIGS. 2 to 4, the first movable lens 35 that forms the second group lens as viewed from the light incident direction is opposed to the first fixed lens 31 at substantially the center in the longitudinal direction of the base 22. Built in. The first movable lens 35 is formed by fixing a first lens 38 to a first lens holder 36 via a lens barrel 37. The first lens 38 is formed of one or a plurality of lens elements combined.

  The first lens holder 36 has a pair of arm portions 36d and 36e (see FIG. 1) extending outward along the diameter direction of the ring portion 36f (see FIG. 1) to which the lens barrel 37 is fixed. Is formed. One arm portion 36d has a sliding hole 36a, and the other arm portion 36e has a sliding groove 36b.

  The first guide shaft 25 is slidably fitted to the first guide shaft 25 and the slide groove 36b is slidably fitted to the second guide shaft 26. The first lens holder 36 is supported across the second guide shaft 26. The first lens holder 36 is movable along the first guide shaft 25 and the second guide shaft 26 in the direction in which the optical axis O extends.

  As shown in FIG. 1, the 1st movable lens 35 has the convex part 36c shorter than one arm part 36d. As shown in FIGS. 1 and 2, a first cam follower 39 is attached to the convex portion 36 c so as to be able to advance and retreat along the direction of projecting and retracting with respect to the tip end surface. The first cam follower 39 has a hemispherical head projecting from the tip surface of the convex portion 36c, and a spherical spring 40 provided by engaging with the base of the head from the convex portion 36c. It is biased in the protruding direction.

  As shown in FIGS. 2 to 4, a second movable lens 41 that forms a third group lens when viewed from the light incident direction is provided at the substantially central portion in the longitudinal direction of the base 22. It is built in between the movable lens 35 so as to oppose them. The second movable lens 41 includes a base member 42, a focus lens 43 that functions as a second lens, a focus lens holder 44 that functions as a second lens holder, a feed screw shaft 45, and the like.

  Similarly to the first lens holder 36, the base member 42 has a pair of arms that extend outward along the diameter direction of the ring portion. Each arm has a sliding hole 42a. The base member 42 has a circular guide hole 42b located between the sliding holes 42a.

  The base member 42 is configured such that the sliding holes 42a are slidably fitted to the first guide shaft 25 and the second guide shaft 26, respectively, so that the first guide shaft 25 and the second guide shaft 26 are fitted. Is supported over. The base member 42 is movable along the first guide shaft 25 and the second guide shaft 26 in the direction in which the optical axis O extends.

  As shown in FIG. 2, the base member 42 is integrally provided with a convex portion 42c facing the convex portion 36c of the first movable lens 35 along the direction in which the optical axis O extends. A second cam follower 46 is attached to the convex portion 42c so as to be able to advance and retreat along the direction of projecting and retracting with respect to the tip end surface. The second cam follower 46 has a hemispherical head protruding from the tip end surface of the convex portion 42c, and a spherical spring 47 provided to engage with the base of the head from the convex portion 42c. It is biased in the protruding direction. The first cam follower 39 and the second cam follower 46 are provided in parallel.

  As shown in FIGS. 3 and 4, a screw shaft arrangement portion 42 d is integrally provided on the second guide shaft 26 side of the base member 42. The screw shaft arrangement portion 42d is located on the opposite side of the second cam follower 46 with the guide hole 42b as a boundary. The screw shaft arrangement portion 42d has wall portions parallel to each other in the direction in which the optical axis O extends.

  The feed screw shaft 45 has an input gear 45a having a diameter larger than that of the screw portion at one end side portion thereof. One end portion of the feed screw shaft 45 is rotatably inserted into a bearing hole provided in one wall portion of the screw shaft arrangement portion 42d, and the other end portion is attached to the other wall portion of the screw shaft arrangement portion 42d. The bearing 48 is rotatably inserted and attached. As a result, the feed screw shaft 45 is arranged in parallel with the direction in which the optical axis O extends and is rotatably supported by the screw shaft arrangement portion 42d.

  The focus lens holder 44 has a pair of arms extending outward along the diameter direction of the ring portion, like the first lens holder 36. Each arm portion has a sliding hole 44a. For example, a short cylindrical sliding portion 44b is provided in the focus lens holder 44 located between the sliding holes 44a.

  The focus lens holder 44 is slidably fitted to the first guide shaft 25 and the second guide shaft 26 so that the slide holes 42a are slidably fitted to the first guide shaft 25 and the second guide shaft 26, respectively. 26 are supported. The focus lens holder 44 is movable along the first guide shaft 25 and the second guide shaft 26 in the direction in which the optical axis O extends.

  The focus lens holder 44 is combined with the base member 42 with its sliding portion 44b slidably fitted into the guide hole 42b. A focus lens 43 is fixed in a sliding portion 44 b of the focus lens holder 44 through a lens barrel 49. Therefore, the sliding portion 44 b is disposed around the focus lens 43. The focus lens 43 is formed of a single lens element or a plurality of lens elements combined. The front surface of the focus lens 43 on the light incident side faces the first lens 38, and the rear surface of the focus lens 43 faces the second fixed lens 33.

  As shown in FIGS. 3 and 4, the focus lens holder 44 has a connecting portion 44c disposed in the screw shaft arranging portion 42d. A nut 50 is press-fitted and fixed to the connecting portion 44c. The nut 50 has a feed screw shaft 45 threaded therethrough. Accordingly, the connecting portion 44c and the screw shaft arrangement portion 42d are connected via the nut 50 and the feed screw shaft 45 that are screwed together, and the base member 42 and the focus lens holder 44 are synchronized via this connection. It is possible to move. A coil spring 51 as a biasing member is sandwiched between the connecting portion 44c and one wall portion of the screw shaft disposing portion 42d facing the connecting portion 44c. The biasing force of the coil spring 51 eliminates the engagement play of the screwing portion, thereby improving the focusing accuracy.

  As shown in FIGS. 1 and 2, a detection convex portion 42 f is integrally projected on the base member 42 of the second movable lens 41 constituting the third group lens. Similarly, a detection convex portion 44f is integrally projected on the focus lens holder 44 of the third lens group. The detection convex portion 42f and the detection convex portion 44f are aligned with each other along the direction in which the optical axis O extends so that they do not interfere with each other.

  The zoom mechanism 28 moves the first movable lens 35 and the second movable lens 41 in synchronization with each other. As shown in FIGS. 1 and 2, the four-group lens and one end in the longitudinal direction of the casing 21 are arranged. It arrange | positions in the space S1 between the walls 21c. The first guide shaft 25, the first cam follower 39, and the second cam follower 46 face the space S1. The zoom mechanism 28 includes a first electric motor 61, a cam 62, and a first transmission member 63.

  As the first electric motor 61, a motor capable of forward and reverse rotation such as a cylindrical stepping motor is used. The first electric motor 61 includes a first support member 65 fixed on the base 22 with a screw 64 (see FIG. 1), and a first motor presser 66 fixed together with the base 22 with the screw 64. It is sandwiched and fixed.

  A drive gear 67 is fixed to the rotating shaft of the first electric motor 61. As shown in FIG. 2, the first transmission member 63 is a gear body having, for example, a large gear 63a and a small gear 63b. The first transmission member 63 is provided such that both ends thereof are rotatably fitted to the base 22 and the first support member 65. The large gear 63 a is meshed with the drive gear 67.

  As shown in FIG. 2, the cam 62 includes a columnar cam element 71 having, for example, helicoid grooves 62 a and 62 b as two cam grooves on the outer peripheral surface, and an input gear 72 attached to one end of the cam element 71. And. The mutual distance between the two helicoid grooves 62 a and 62 b is the same as the mutual distance between the first cam follower 39 and the second cam follower 46. Note that the maximum zooming dimension is set to 7 mm to 10 mm, for example, by the helicoid grooves 62a and 62b.

  The cam 62 is rotatably provided in the casing 21 in a posture parallel to the optical axis O. That is, the shaft portion protruding from one end of the cam 62 in the axial direction is fitted into the bearing hole 22b provided in the base 22 and is rotatably supported. A shaft portion protruding from the other axial end of the cam 62 is rotatably supported by a cam support portion 66 a formed on the first motor presser 66 via a bearing 73.

  The input gear 72 having a diameter larger than that of the cam element 71 is engaged with the small gear 63 b of the first transmission member 63. Therefore, the first transmission member 63 functions as a transmission means for interlocking the cam 62 with the drive gear 67. In this transmission means, at least one of the large gear 63a and the small gear 63b may be formed integrally with the shaft portion to which the large gear 63a or the small gear 63b is attached, or may be separately formed and connected to the shaft portion. Also good. Further, in order to increase the speed reduction ratio or speed increase ratio in the interlocking, the first transmission member 63 may be a gear train used in plural.

  The hemispherical head of the first cam follower 39 included in the first movable lens 35 is slidably engaged with one helicoid groove 62a of the cam element 71. Similarly, the hemispherical head of the second cam follower 46 included in the second movable lens 41 is slidably engaged with the other helicoid groove 62b of the cam element 71.

  Reference numeral 74 in FIG. 2 indicates an urging body such as a coil spring. One end of the coil spring 74 is brought into contact with a spring receiving plate 75 fixed to the back surface of the front wall 23 a of the cover 23, and the other end is brought into contact with the bearing 73. Yes. The coil spring 74 urges the cam 62 toward the base 22. By this urging, the play between the helicoid groove 62a and the first cam follower 39 engaged with the helicoid groove 62a is lost, and between the helicoid groove 62b and the second cam follower 46 engaged therewith. The play between them is lost, and the movement accuracy of the movable lenses 35 and 41 in the zoom operation (magnification operation) can be improved.

  The focus mechanism 29 performs a focusing operation by rotating the feed screw shaft 45. As shown in FIGS. 1, 3, and 4, the other end wall in the longitudinal direction of the four-group lens and the casing 21 is provided. It is arranged in the space S2 between 21d. In this space S2, the second guide shaft 26, the detection convex portion 42f, and the detection convex portion 44f face. The focus mechanism 29 includes a second electric motor 81, a drive shaft 82, and a second transmission member 83.

  As the second electric motor 81, a motor capable of forward and reverse rotation such as a stepping motor having a cylindrical shape is used. The second electric motor 81 includes a second support member 85 fixed on the base 22 with a screw 84 (see FIGS. 1 and 2), and a second motor presser fastened to the base 22 with the screw 84. 86 and is fixed.

  A drive gear 87 is fixed to the rotation shaft of the second electric motor 81. As shown in FIGS. 3 and 4, the second transmission member 83 is a gear body having, for example, a large gear 83a and a small gear 83b. The second transmission member 83 is provided such that both ends thereof are rotatably fitted to the base 22 and the second support member 85. The large gear 83 a is meshed with the drive gear 87.

  As shown in FIGS. 3 and 4, the drive shaft 82 includes a gear portion 82a and an input gear 82b provided continuously at one end of the gear portion 82a. The drive shaft 82 is rotatably provided in the casing 21 in a posture parallel to the optical axis O. That is, the shaft portion protruding from one end of the drive shaft 82 in the axial direction is fitted in the bearing hole 22 d provided in the base 22 and is rotatably supported. The shaft portion protruding from the other axial end of the drive shaft 82 is fitted in a bearing hole 86b provided in a cam support portion 86a formed in the second motor presser 86 and is rotatably supported.

  An input gear 82b having a diameter larger than that of the gear portion 82a is engaged with the small gear 83b of the second transmission member 83. Therefore, the second transmission member 83 functions as a transmission unit that links the drive shaft 82 to the drive gear 87. In this transmission means, at least one of the large gear 83a and the small gear 83b may be formed integrally with the shaft portion to which the large gear 83a or the small gear 83b is attached, or may be separately formed and connected to the shaft portion. Also good. Further, in order to increase the speed reduction ratio or speed increase ratio in the interlocking, the second transmission member 83 may be a gear train using a plurality.

  The gear portion 82a has an axial shape and extends in the direction in which the optical axis O extends, and the length thereof is longer than the maximum zoom dimension (maximum variable magnification dimension) by the zoom mechanism 28. The gear portion 82 a is engaged with the input gear 45 a of the feed screw shaft 45.

  Moreover, as shown in FIG.1 and FIG.2, the 1st detection part 91 and the 2nd detection part 92 are arrange | positioned in the casing 21 through the other end wall 21d. The detectors 91 and 92 are supported by a reinforcing plate 94 (see FIGS. 1 and 2) to which a flexible wiring board 93 attached over the outer surface of one side wall 21a and both end walls 21c and 21d of the casing 21 is attached. The flexible wiring board 93 is also electrically connected to the first electric motor 61 and the second electric motor 81.

  For these detection units 91 and 92, photo interrupters having a substantially U-shape when viewed from the subject side are used. A detection convex portion 44f of the focus lens holder 44 is inserted into the detection groove of the first detection portion 91 so as to be movable in the direction in which the optical axis O extends. A detection convex portion 42f of the base member 42 is inserted into the detection groove of the second detection portion 92 so as to be movable in the direction in which the optical axis O extends. Information for obtaining a reference position (origin) at the time of starting focusing (focusing) is detected by the first detection unit 91 and the detection convex portion 44f, and the second detection unit 92 and the detection convex portion 42f change the magnification. Information for obtaining a reference position (origin) when starting (zooming) is detected.

  As shown in FIG. 5, the circuit block 13 includes a controller 111, motor drivers 112 and 113, a signal processor 114, and the like.

  The control unit 111 includes a CPU, a memory, and the like. The control for driving the image sensor 14, the control for driving the zoom mechanism 28 to perform zooming, the control for driving the focus mechanism 29 to execute focusing, and the like. It is responsible for overall control of the camera module 11 including The motor driver 112 applies the necessary number of drive pulses to the first electric motor 61 when driving the zoom mechanism 28. Similarly, the motor driver 113 is used when driving the focus mechanism 29. A necessary number of drive pulses are applied to the second electric motor 81.

  The signal processing unit 114 processes the image signal output from the image sensor 14 and supplies the processed image signal to the control unit 111. A semiconductor device such as a CCD or a CMOS is used for the image sensor 14. As shown in FIGS. 2 to 4, the imaging element 14 is disposed on the optical axis O so as to face the second fixed lens 33.

  The printed wiring board 115 that supports the image sensor 14 is positioned and fixed on the back surface of the base 22, and the printed wiring board 115 and the flexible wiring board 93 are connected to a mother board (not shown). A control unit 111, motor drivers 112 and 113, a signal processing unit 114, and the like are mounted on this motherboard. Note that reference numeral 116 in FIG. 5 denotes a display unit including an LCD or the like. The display unit 116 is provided in a portable electronic device in which the camera module 11 is incorporated, and displays image information captured by the image sensor 14 and memory information of the memory.

  In the camera module 11 having the above configuration, the zoom mechanism 28 and the focus mechanism 29 built in the casing 21 are arranged separately on both sides of the lens having the four-group configuration. For this reason, the shape of the casing 21 viewed from the subject side can be formed in a rectangular shape in which one of the longitudinal and lateral dimensions of the casing 21 is narrower than the other. In this case, the elements of the zoom mechanism 28 and the focus mechanism 29 are not arranged in the direction orthogonal to the arrangement direction as shown in FIG. The one side wall 21a and the other side wall 21b are as close as possible to the lens having the four-group configuration, and the gap g (see FIG. 1) between the lens group and the one side wall 21a and the other side wall 21b can be reduced. That is, the dimension between the one side wall 21a and the other side wall 21b of the casing 21 can be made slightly larger than the diameter of the four-group lens. Therefore, this camera module 11 is suitable for mounting on a portable device such as a camera-equipped mobile phone.

  When the camera module 11 having the above-described configuration is used, first, the zoom mechanism 28 is driven, and the first movable lens 35 and the second movable lens 41 are synchronized so that the optical axis O extends. Along the direction from the origin position to the magnification position (zoom position).

  That is, when the first electric motor 61 is driven, the rotational power of the first electric motor 61 meshes with the driving gear 67 and the large gear 63a of the first transmission member 63, and the small gear 63b of the first transmission member 63. The cam 62 is transmitted to the cam 62 while being decelerated by meshing with the input gear 72. According to the rotation of the cam 62, the first movable lens 35, which is stopped by the first guide shaft 25 and the second guide shaft 26, is engaged with the helicoid groove 62a of the cam element 71. Is moved along the first guide shaft 25 and the second guide shaft 26 in the direction in which the optical axis O extends through the cam follower 39. At the same time, the second movable lens 41 extends in the direction in which the optical axis O extends in the same direction as the first movable lens 35 via the second cam follower 46 engaged with the helicoid groove 62b of the cam element 71. It is moved along the first guide shaft 25 and the second guide shaft 26 by the same distance.

  The zoom mechanism 28 rotates the columnar cam 62 as described above, and the engagement position of the first cam follower 39 with respect to the helicoid groove 62a and the engagement of the second cam follower 46 with respect to the helicoid groove 62b. Since the movable lenses 35 and 41 are synchronously moved to the variable magnification position by changing the combined positions, the movable lenses 35 and 41 are roughly moved to the variable magnification position quickly according to the lead angle of the helicoid grooves 62a and 62b. This is preferable in that it is suitable for moving, and the maximum dimension of the maximum movement can be secured according to the length of the cylindrical cam 62.

  During zooming due to such movement, the relative position between the base member 42 of the second movable lens 41 and the focus lens holder 44 does not change, but the second movable lens 41 with respect to the drive shaft 82 of the focus mechanism 29 does not change. The position changes. In this case, the input gear 45a of the feed screw shaft 45 slides on the gear portion 82a of the drive shaft 82, and the meshing between the input gear 45a and the gear portion 82a is maintained. For this reason, the focusing operation by the focus mechanism 29 at the zoom position described below can be realized.

  Next, the focus mechanism 29 is operated to perform a focusing operation.

  That is, when the second electric motor 81 is driven, the rotational power of the second electric motor 81 meshes with the driving gear 87 and the large gear 83a of the second transmission member 83, and the small gear 83b of the second transmission member 83. It is transmitted to the drive shaft 82 while being decelerated by meshing with the input gear 82b of the drive shaft 82. Further, the rotation of the drive shaft 82 is transmitted to the feed screw shaft 45 while being decelerated by meshing between the gear portion 82a and the input gear 45a of the feed screw shaft 45. In accordance with the rotation of the feed screw shaft 45, the focus lens holder 44, which is prevented from rotating by the first guide shaft 25 and the second guide shaft 26, meshes with the nut 50 fixed thereto and the feed screw shaft 45. Is changed, the optical axis O is moved in the extending direction. For this reason, the focus lens 43 held by the focus lens holder 44 is finely moved to the in-focus position.

  In this focusing, as described above, the change in meshing between the nut 50 provided on the focus lens holder 44 and the feed screw shaft 45 rotated by the focus mechanism 29 causes the focus lens 43 to rotate with respect to the rotation of the feed screw shaft 45. The feed amount can be controlled minutely. Therefore, focusing can be performed with high accuracy.

  Moreover, the sliding portion 44b of the focus lens holder 44 that is moved with respect to the base member 42 held in a stationary state slides in the guide hole 42b of the base member 42 during focusing. That is, the focus lens holder 44 is supported not only by the screwed portion with the feed screw shaft 45 via the nut 50 but also by the guide hole 42b. For this reason, it is reduced that the weights of the focus lens holder 44, the focus lens 43, the lens barrel 49, and the like are concentrated on the threaded portion between the feed screw shaft 45 and the nut 50. In addition, the slide hole 44 a of the focus lens holder 44 is slidably fitted to the first guide shaft 25 and the second guide shaft 26. Also in this point, it is reduced that the weights of the focus lens holder 44, the focus lens 43, the lens barrel 49, and the like are concentrated on the threaded portion between the feed screw shaft 45 and the nut 50. Therefore, since the focus lens holder 44 is not moved in a cantilever state with the screwing portion as a fulcrum, the focusing operation is smoothed and the durability of the screwing portion can be improved.

  The present invention is not limited to the one embodiment. For example, the lens group only needs to have at least one fixed lens and two movable lenses, and is not limited to the four-group configuration. In the case where the lens group has a four-group configuration, the first movable lens 35 for zooming and the second movable lens 41 for zooming and focusing are reversed from the above-described one embodiment. Alternatively, the second movable lens 41 may be opposed to the first fixed lens 31, and the first movable lens 35 may be disposed opposite to the second fixed lens 33. In this case, the second movable lens 41 is used as the second group lens, and the first movable lens 35 is used as the third group lens.

The figure which shows the layout of each component planarly in the state which partially cut away the cover of the lens drive device which concerns on one Embodiment of this invention. Sectional drawing which shows the lens drive device which concerns on one Embodiment along F2-F2 line | wire in FIG. Sectional drawing which shows the lens drive device which concerns on one Embodiment along the F3-F4 line | wire in FIG. 1 in the state in which the movable lens was arrange | positioned in the origin position. Sectional drawing which shows the lens drive device which concerns on one Embodiment along the F3-F4 line | wire in FIG. 1 in a focus completion state. FIG. 3 is a block diagram illustrating a configuration of a camera module including the lens driving device according to the first embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Camera module 12 ... Lens drive device 13 ... Circuit block 14 ... Image pick-up element 21 ... Casing 21a ... One side wall of casing 21b ... Other side wall of casing 21c ... One end wall of casing 21d ... Other end wall of casing 22 ... Base 23 ... Cover 25 ... first guide shaft 26 ... second guide shaft 31 ... first fixed lens 33 ... second fixed lens 35 ... first movable lens 39 ... first cam follower 41 ... second movable Lens 42 ... Base member 42a ... Slide hole 42b ... Guide hole 42d ... Screw shaft arrangement part 43 ... Focus lens 44 ... Focus lens holder 44a ... Slide hole 44b ... Slide part 45 ... Feed screw shaft 45a ... Feed screw shaft Input gear 46 ... second cam follower 50 ... nut 61 ... first electric motor 62 ... cam 62a ... helicoid groove Groove)
62b ... Helicoid groove (cam groove)
DESCRIPTION OF SYMBOLS 81 ... 2nd electric motor 82 ... Drive shaft 82a ... Gear part 83 ... 2nd transmission member 111 ... Control part O ... Optical axis

Claims (7)

A casing having a rectangular parallelepiped shape and having a guide member and a fixed lens attached at an intermediate position in the longitudinal direction;
A first movable lens built in the casing and moved in a direction in which an optical axis extends along the guide member;
A second movable lens that is built in the casing so as to face the first movable lens and is moved in the direction in which the optical axis extends along the guide member;
It is located between the lens group of the fixed lens and both movable lenses and one end wall in the longitudinal direction of the casing, and is provided in the casing, and includes a first electric motor. A zoom mechanism for moving the two movable lenses synchronously;
The first and second movable lenses, which are located between the lens group and the other end wall in the longitudinal direction of the casing and are built in the casing, include a second electric motor, and are moved by the zoom mechanism. A focus mechanism for moving one of the motors by the power of the second electric motor;
Comprising
One of the first and second movable lenses has a screw shaft placement portion and is moved along the guide member, and the focus is supported rotatably on the screw shaft placement portion. A focus lens that has a feed screw shaft that is rotated by a mechanism and a nut that holds the focus lens and is screwed to the feed screw shaft, and is movable in the direction in which the optical axis extends with respect to the base member A lens driving device comprising a holder.   The zoom mechanism includes a cylindrical cam having a cam groove on a peripheral surface and extending in a direction in which the optical axis extends, and the first electric motor that rotates the cam. The lens driving device according to claim 1, wherein a cam follower provided on each of the base member and the other movable lens with respect to the movable lens is engaged.   The focus mechanism includes a drive shaft having a gear portion extending in a direction in which the optical axis extends longer than a maximum zoom dimension by the zoom mechanism, and the second electric motor for rotating the drive shaft, The lens driving device according to claim 1, wherein an input gear that slidably engages with the gear portion along an axial direction is provided on the feed screw shaft. A casing having a rectangular parallelepiped shape and having a guide member and a fixed lens attached at an intermediate position in the longitudinal direction;
A first movable lens that has a first cam follower and is built in the casing and is moved in the direction in which the optical axis extends along the guide member;
A second movable lens having a second cam follower, which is built in the casing so as to face the first movable lens and is moved in a direction in which the optical axis extends along the guide member;
Positioned between the lens group of the fixed lens and both movable lenses and one end wall of the casing in the longitudinal direction, the cam is engaged with the first and second cam followers and is built in the casing. A zoom mechanism that includes a cam that extends in a direction in which the optical axis extends, and a first electric motor that rotates the cam, and moves the first and second lenses synchronously;
A drive shaft having a gear portion that is positioned between the lens and the other end wall in the longitudinal direction of the casing and is built in the casing and extends in a direction in which the optical axis extends longer than a maximum zoom dimension by the zoom mechanism; And a focus mechanism comprising a second electric motor that rotates the drive shaft;
Comprising
One of the first and second lenses is
A base member that is moved along the guide member with a screw shaft arrangement portion arranged near one of the first and second cam followers and the drive shaft;
A feed screw shaft having an input gear slidably engaged with the gear portion along the axial direction of the drive shaft and rotatably supported by the screw shaft arrangement portion;
A focus lens holder that holds a focus lens and has a nut that engages with the feed screw shaft and is movable in a direction in which the optical axis extends with respect to the base member;
A lens driving device.   2. A guide hole is provided in the base member, and a sliding portion located around the focus lens is provided in the focus lens holder, and the sliding portion is slidably fitted into the guide hole. The lens driving device according to any one of 4.   The lens driving device according to claim 1, wherein a plurality of sliding holes that are slidably fitted into the guide member are provided in the focus lens holder. A lens driving device according to any one of claims 1 to 6;
An image sensor disposed on the optical axis of the lens driving device;
A control unit that controls the zoom mechanism included in the lens driving device to perform zooming, and controls the focusing mechanism included in the lens driving device to execute focusing;
A camera module.

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