JP2008185749A - Lens drive unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize a lens drive unit having a voice coil type motor as a drive source. <P>SOLUTION: The lens drive unit is equipped with: bases 10 and 20; a cylindrical lens frame 30 holding a lens G; two guide shafts 41 and 42 fixed on the base so as to guide the lens frame 30 in an optical axis direction L; an annular magnet 50 provided to the lens frame 30; and an annular coil 60 and a yoke 70 having a U-shaped cross section and formed in a double cylindrical state having an inside cylinder part 71 and an outside cylinder part 72, which are provided to the base 20. The two guide shafts 41 and 42 are arranged on the outside of the magnet 50, the coil 60 and the yoke 70 in a radial direction perpendicular to the optical axis L, and the lens frame 30 has fitting parts 34 and 35 formed to project in the radial direction and fit to the two guide shafts to freely slide. Thus, the drive unit is made compact in the radial direction perpendicular to the optical axis and thinned in the optical axis direction, so that the unit is made compact as a whole. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lens driving device that drives a lens in the optical axis direction, and more particularly, to a lens driving device that is mounted on, for example, a portable information terminal device that is required to be downsized using a voice coil motor as a driving source.

  As a conventional lens driving device, an annular lens holding frame for holding a lens, two fitting holes provided at two positions on the outer periphery of the lens holding frame, and a lens holding by being slidably inserted into two fitting holes Two guide shafts for guiding the frame in the optical axis direction, a bobbin fixed around the lens holding frame on the outer side in the radial direction from the guide shaft, a coil wound around the bobbin, a guide holding shaft and a lens holding frame A lens barrel that houses a coil, a magnet that is fixed to the inner peripheral surface of the lens barrel on the radially outer side of the coil, and a yoke that is joined to the magnet and bent in a non-contact manner between the coil and the lens holding frame Etc., and a voice coil type motor in which the coil moves while the magnet and the yoke are stationary is known (see, for example, Patent Document 1).

  As other lens driving devices, there are a lens holding frame for holding the lens, fitting holes and U-shaped fitting recesses formed in two arm portions projecting radially from the lens holding frame, fitting Two guide shafts that are slidably inserted into the holes and fitting recesses to guide the lens holding frame in the optical axis direction, and are bent into a U-shape that is fixed to the radially outer side of the arm portion that forms the fitting hole. A yoke, a magnet fixed to the yoke, a lens barrel that holds the guide holding shaft and the lens holding frame, the magnet, and the yoke, an annular coil fixed to the inner peripheral surface of the lens barrel on the radially outer side from the magnet, etc. And a voice coil motor in which a magnet and a yoke move while the coil is stationary is known (see, for example, Patent Document 2).

However, in these lens driving devices, the two guide shafts for guiding the lens frame are arranged at the most center (optical axis) in the radial direction, and sequentially on the outside of the guide shaft, the coil → the magnet and the yoke, or The magnet and the yoke → coil are arranged.
Therefore, although the two guide shafts are partially disposed in two locations in the vicinity of the outer periphery of the lens holding frame, if a magnet, a yoke, a coil, or the like is formed in an annular shape, the overall size is increased in the radial direction. .
In addition, when driving the lens holding frame (lens) in the optical axis direction using this voice coil motor as a drive source, the position of the lens holding frame in the optical axis direction is not detected, but the image passing through the lens is not detected. Since the imaging state is monitored and controlled by a closed loop of CCD / AF, the control is very difficult.
Furthermore, when it is mounted on a portable information terminal device or the like, it is necessary to reduce the thickness in the optical axis direction in addition to the reduction in size in the radial direction (smaller diameter). In the arrangement configuration of the guide shaft, a useless space is caused and it is difficult to reduce the thickness.

JP-A-6-201975 JP 2000-32475 A

  The present invention has been made in view of the above-mentioned circumstances, and the object is to simplify the structure, consolidate parts, downsize in the radial direction perpendicular to the optical axis (reduce the diameter), An object of the present invention is to provide a lens driving device capable of driving a lens smoothly and accurately in the optical axis direction while reducing the thickness in the axial direction.

The lens driving device of the present invention includes a base, a cylindrical lens frame that holds the lens, two guide shafts fixed to the base to guide the lens frame in the optical axis direction, and an annularly formed coil. A lens driving device comprising: a magnet formed in an annular shape; and a yoke formed in a double cylindrical shape having a U-shaped cross section and an inner cylindrical portion and an outer cylindrical portion, wherein the magnet includes: Provided on one of the lens frame and base, the coil and yoke are provided on the other of the lens frame and base, and the two guide shafts are arranged outside the magnet, coil and yoke in the radial direction perpendicular to the optical axis. The lens frame has a fitting portion that protrudes in the radial direction and is slidably fitted to two guide shafts.
According to this configuration, the annular magnet, the annular coil, and the annular yoke are disposed around the cylindrical lens frame that holds the lens, and the two guide shafts are disposed on the outside thereof. Around the lens frame, magnets, coils, and yokes can be arranged close to the center (optical axis), and the device can be reduced in diameter in the radial direction perpendicular to the optical axis and thinned in the optical axis direction. As a whole, the apparatus can be miniaturized.

In the above configuration, a configuration in which the two guide shafts are arranged on or near a straight line orthogonal to the optical axis can be adopted.
According to this configuration, for example, when the base has a substantially rectangular shape or a substantially elliptical shape corresponding thereto, two guide shafts are arranged at two corners on the diagonal line or at both ends on the long axis among the four corners. The apparatus can be further downsized while effectively utilizing the space and consolidating the whole.

In the above configuration, the coil and the yoke are fixed to the base, and the magnet is fixed to the lens frame so as to define at least a part of the outer peripheral surface of the lens frame. A configuration having an annular recess that receives the cylindrical portion in a non-contact manner can be employed.
According to this configuration, the ring-shaped magnet functions as a mover that moves integrally with the lens frame, the coil and yoke are fixed to the base and function as a stator, and the magnet functions as the outer peripheral surface of the lens frame. Since the inner cylindrical part of the yoke is formed so as to enter the annular recess of the lens frame and these yokes and magnets are further concentrated closer to the center, the wasted space is formed. Can be saved as much as possible, and the apparatus can be further downsized (smaller diameter). Further, since the coil is fixed to the base and functions as a stator, the wiring can be easily routed, and disconnection or the like can be more reliably prevented as compared with the case where the coil is movable.

In the above configuration, the magnet and the lens frame may employ a configuration in which two colors are molded using a resin material.
According to this configuration, it is possible to reduce the weight by adopting a resinized magnet (plastic magnet) and a resinized lens frame, and further reducing the size by integrally forming as a two-color molding. be able to.

The said structure can employ | adopt the structure which has the urging member which urges | biases a lens frame to one direction of an optical axis direction.
According to this configuration, when the coil is energized with the urging force of the urging member applied, the generated electromagnetic driving force moves the lens frame against the urging force. When the urging force and the electromagnetic driving force are balanced, the lens frame stops. Therefore, the lens frame (and the lens) can be moved to a desired position with high accuracy by appropriately controlling the current (applied voltage) flowing through the coil.

In the above configuration, the biasing member may be a coil spring that is coaxially disposed around the guide shaft and that exerts a biasing force between the fitting portion of the base and the lens frame.
According to this configuration, since the urging member is a coil spring that is fitted around the guide shaft, a dedicated arrangement space is not required, and parts can be integrated, and the apparatus can be downsized.

In the above configuration, a configuration having a resistance member that exerts a resistance force to the movement of the lens frame can be employed.
According to this configuration, when the coil is energized in a state where the resistance force of the resistance member is applied, the generated electromagnetic driving force overcomes the resistance force and moves the lens frame. Therefore, the lens frame (and the lens) can be moved to a desired position with high accuracy by appropriately controlling the current (applied voltage) flowing through the coil.

In the above configuration, the resistance member may be a cantilever spring having one end fixed to the lens frame and the other end slidably pressed against the outer peripheral surface of the guide shaft.
According to this configuration, since the resistance member is a cantilever spring that slidably contacts the guide shaft, a dedicated arrangement space is not required, and parts can be consolidated and the apparatus can be downsized.

In the above configuration, it is possible to employ a configuration having detection means for detecting the position of the lens frame in the optical axis direction.
According to this configuration, the position of the lens frame (lens) is not controlled via a monitor as in the prior art, but is directly driven and controlled based on the detection signal of the detection means. It can be moved and positioned with high accuracy.

In the above configuration, the detection means includes a magnetic sensor provided on one of the base and the lens frame, and a magnetized member provided on the other of the base and the lens frame and magnetized by being arrayed in the optical axis direction. A configuration can be employed.
According to this configuration, since the detection means is the magnetic sensor and the magnetized member, highly accurate detection can be performed without contact.
For example, high-frequency magnetization (for example, several KHz / movement amount) is applied to the magnetized member, the magnetized pattern is read by a magnetic sensor (for example, MR element, Hall element, etc.), and the voltage is converted. By counting the number, the relative position of the lens frame can be recognized and controlled, and the magnetized member is magnetized at a low frequency (for example, 0.5 Hz / movement amount). The magnetic sensor (for example, MR element, Hall element, etc.) reads the magnetized pattern, converts the voltage, and recognizes the absolute position of the lens frame from information (map) showing the relationship between the voltage and the amount of movement prepared in advance. Drive control.

In the above configuration, a configuration in which the magnetic sensor is fixed to the lens frame and the magnetized member also serves as a guide shaft can be adopted.
According to this configuration, since the magnetized member also serves as the guide shaft, the number of parts can be reduced despite the increased detection function, and the apparatus can be simplified and downsized (smaller diameter and thinner). .

In the above configuration, the detection means may employ a configuration including an optical sensor provided on the base and a detected piece provided on the lens frame and detected by the optical sensor.
According to this configuration, since the detection means is an optical sensor (for example, a photo interrupter) and a detected piece, highly accurate detection can be performed without contact.
For example, an analog component of the output of the optical sensor can be extracted, and drive control can be performed by recognizing the absolute position of the lens frame from information (map) indicating the relationship between the voltage and movement amount prepared in advance.

  According to the lens driving device having the above-described configuration, the lens can be manufactured while simplifying the structure, consolidating parts, reducing the size in the radial direction perpendicular to the optical axis (reducing the diameter), and reducing the thickness in the optical axis direction. It can be driven smoothly and accurately in the direction of the optical axis. Therefore, it is suitable for a mobile camera mounted on a portable information terminal device or the like that is required to be downsized.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of the invention will be described with reference to the accompanying drawings.
1 to 3 show an embodiment of a lens driving device according to the present invention. FIG. 1 is a front view of the device, FIG. 2 is a cross-sectional view of the device including the optical axis, and FIG. It is sectional drawing in a surface perpendicular | vertical to the optical axis of an apparatus.
As shown in FIGS. 1 to 3, the lens driving device is configured to guide a substrate 10 and a cover plate 20 as a base, a cylindrical lens frame 30 that holds a lens G, and the lens frame 30 in an optical axis direction L. Two guide shafts 41 and 42 fixed to the base (substrate 10 and cover plate 20), an annular magnet 50 provided on the lens frame 30, an annular coil 60 provided on the cover plate (base) 20 and a double A cylindrical yoke 70 is provided.

As shown in FIGS. 1 to 3, the substrate 10 is formed in a contour that is curved by removing the two corners of the rectangle R indicated by a two-dot chain line, and exposes the lens G, using a resin material or the like. Fixing holes 12, 13 and the like for fitting and fixing the circular opening 11 and the guide shafts 41, 42, respectively, are provided.
The cover plate 20 is formed with the same outline as the substrate 10 using a resin material or the like, as shown in FIGS. 1 to 3, with the two corners of the rectangle R indicated by a two-dot chain line removed and curved. , A circular opening 21 for exposing the lens G, fixing holes 22 and 23 for fixing and fixing the guide shafts 41 and 42, a cylindrical portion 24 for fixing the yoke 70, and the like.

  As shown in FIGS. 1 to 3, the lens frame 30 is made of a resin material or the like, as shown in FIGS. 1 to 3, a cylindrical portion 31 that holds the lens G, and an arm portion 32 that is formed to project radially from the outer peripheral surface of the cylindrical portion 31. 33, a bifurcated branch at the tip of the arm 32, a fitting part 34 for defining a fitting hole 34a for slidably fitting the guide shaft 41, and a substantially U-shaped at the tip of the arm 33 The recess 35a is formed in the recess 35a so that the guide shaft 42 is slidably fitted (inserted), and the annular recess 36 is formed so as to reduce the outer peripheral surface of the cylindrical portion 31 and to which the magnet 50 is coupled. An annular recess 37 and the like that are further reduced in diameter than the annular recess 36 and receive an inner cylindrical portion 71 of a yoke 70 described later are provided.

The magnet 50 forms a part of a voice coil motor, and is formed in an annular shape (cylindrical shape) as shown in FIGS. 1 to 3 and is formed integrally with the cylindrical portion 31 of the lens frame 30. Has been. That is, the magnet 50 is formed so that one end side is integrally molded and fixed to the annular recess 36 of the cylindrical portion 31, and its outer peripheral surface defines a part of the outer peripheral surface of the cylindrical portion 31.
Here, the magnet 50 and the lens frame 30 are formed by so-called two-color molding, in which the lens frame 30 molded in advance using a resin material is continuously molded using a resin material mixed with magnetic powder. .
Thus, by forming the magnet 50 and the lens frame 30 by two-color molding using a resin material, it is possible to further reduce the size while achieving weight reduction.

The guide shaft 41 is formed using a highly rigid metal material or the like so as to have a circular cross section and extend in the optical axis direction L as shown in FIGS. The guide shaft 41 is fitted and fixed at one end to the fixing hole 12 of the substrate 10 and is slidably inserted into the fitting hole 34 a of the lens frame 30. The fixing hole 22 is fitted and fixed.
That is, the guide shaft 41 mainly guides the lens frame 30 in the optical axis direction L without rattling (inclination).

As shown in FIGS. 1 to 3, the guide shaft 42 is formed using a highly rigid metal material or the like so as to have a circular cross section and extend in the optical axis direction L. One end of the guide shaft 42 is fitted and fixed in the fixing hole 13 of the substrate 10 and is slidably inserted into the U-shaped recess 35a of the lens frame 30, and the other end is the cover plate. 20 fixed holes 23 are fitted and fixed.
That is, the guide shaft 42 guides the lens frame 30 in the optical axis direction L and mainly restricts the lens frame 30 from rotating around the guide shaft 41.
The two guide shafts 41 and 42 also serve to connect and fix the substrate 10 and the cover plate 20. Therefore, another member for connecting the substrate 10 and the cover plate 20 becomes unnecessary, and the number of parts can be reduced.

The coil 60 forms a part of a voice coil type motor, and is previously formed into an annular shape (cylindrical shape) as shown in FIGS. 1 to 3, and thereafter, via an outer cylindrical portion 72 of a yoke 70 described later. And is fixed to the cylindrical portion 24 of the cover plate 20.
The coil 60 has an outer peripheral surface 61 joined to the outer cylindrical portion 72 of the yoke 70, and an inner peripheral surface 62 facing the outer peripheral surface of the magnet 50 and the outer peripheral surface of the cylindrical portion 31 with a predetermined gap. Are arranged to be.

The yoke 70 is a part of a voice coil motor, and has a U-shaped cross section and a double cylindrical shape having an inner cylindrical portion 71 and an outer cylindrical portion 72 as shown in FIGS. The outer cylindrical portion 72 is formed in advance, and then fixed to the cylindrical portion 24 of the cover plate 20, and the coil 60 is fitted inside the outer cylindrical portion 72 and held.
The inner cylindrical portion 71 is inserted in a non-contact manner with respect to the annular recess 37 formed between the magnet 50 and the cylindrical portion 31, and the lens frame 30 and the magnet 50 move in a non-contact manner in the optical axis direction L. Is allowed.

In the above configuration, the annular magnet 50 is disposed flush with the cylindrical lens frame 30, the annular coil 60 and the yoke 70 are disposed outside thereof, and the two guide shafts 41 and 42 are disposed outside thereof. Therefore, around the lens G and the lens frame 30, the magnet 50, the coil 60, and the yoke 70 can be arranged so as to be gathered closer to the center (optical axis L), and the apparatus can be arranged in the radial direction perpendicular to the optical axis L. The diameter can be reduced and the optical axis direction L can be reduced, and the apparatus can be reduced in size as a whole.
Further, as shown in FIG. 1, the two guide shafts 41 and 42 are arranged on a straight line perpendicular to the optical axis L, that is, at two diagonal corners of the four corners of the rectangle R, so that the space is effectively used. In addition, the apparatus can be further reduced in size while consolidating the whole.

  In particular, the coil 60 and the yoke 70 are fixed to the cover plate 20 (the coil 60 and the yoke 70 are fixed to the cover plate (base) 20 and function as a stator), and the magnet 50 is defined to define the outer peripheral surface of the lens frame 30. The annular recess 37 is fixed to the lens frame 30 (the magnet 50 functions as a mover that moves integrally with the lens frame 30) and receives the inner cylindrical portion 71 of the yoke 70 in a non-contact manner on the radially inner side of the magnet 50. By providing the lens frame 30 on the lens frame 30, the yoke 70 and the magnet 50 can be further concentrated near the center, and also in the optical axis direction L, the magnet 50 and the yoke 70 (inner cylindrical portion 71) and the lens frame 30 can be arranged. Since the cylindrical portions 31 are arranged so as to overlap with each other, useless space can be saved as much as possible, and the device can be further downsized (smaller diameter) and thinner in the optical axis direction L. Rukoto can.

Next, the operation of this driving device will be briefly described. When the coil 60 is energized in one direction, the lens frame 30 and the magnet 50 are immediately activated by the generated electromagnetic driving force, and the optical axis direction L When the coil 60 is energized in the other direction, the lens frame 30 and the magnet 50 are moved by the reverse electromagnetic driving force generated when the coil 60 is energized in the other direction. Then, it starts immediately, moves in the other direction of the optical axis direction L, contacts the part of the substrate 10 and stops.
Thus, since the generated electromagnetic driving force is larger than the sliding resistance or inertial force of the lens frame 30, the lens frame 30 (lens G) is immediately moved to two positions in the optical axis direction L. It is done. Therefore, it is suitable when the lens G is switched at two positions in the optical axis direction L.

FIG. 4 is a cross-sectional view showing another embodiment of the lens driving device according to the present invention. Since this embodiment is the same as the above-described embodiment except that the coil spring 100 as an urging member is provided, the same components are denoted by the same reference numerals and description thereof is omitted.
That is, in this apparatus, as shown in FIG. 4, a coil spring 100 that urges the lens frame 30 in one direction of the optical axis direction L is provided.
As shown in FIG. 4, the coil spring 100 is coaxially disposed around the guide shaft 41, one end of which is in contact with the back surface of the cover plate 20, and the other end is the front surface of the fitting portion 34 of the lens frame 30. Attached in a compressed state.

Therefore, when the coil 60 is energized in a state where the biasing force of the coil spring 100 is applied, the generated electromagnetic driving force moves the lens frame 30 (and the magnet 50) against the biasing force. Then, when the biasing force and the electromagnetic driving force are balanced, the lens frame 30 (and the magnet 50) stops. That is, the lens frame 30 (and the lens G) can be moved to a desired position with high accuracy by appropriately controlling the current (applied voltage) flowing through the coil 60.
Here, since the coil spring 100 fitted around the guide shaft is employed as the urging member, a dedicated arrangement space is not required, and parts can be consolidated and the apparatus can be downsized.

FIG. 5 is a cross-sectional view showing still another embodiment of the lens driving device according to the present invention. Since this embodiment is the same as the above-described embodiment except that the cantilever spring 110 as a resistance member is provided, the same components are denoted by the same reference numerals and the description thereof is omitted.
That is, in this apparatus, as shown in FIG. 5, a cantilever spring 110 is provided that exerts a resistance force against the movement of the lens frame 30.
As shown in FIG. 5, the cantilever spring 110 has one end fixed to the fitting portion 34 of the lens frame 30 and the other end generating a predetermined frictional resistance force with the outer peripheral surface of the guide shaft 41. Is slidably pressed.

Therefore, when the coil 60 is energized with the resistance force of the cantilever spring 110 applied, the generated electromagnetic driving force overcomes the resistance force and moves the lens frame 30 and the magnet 50. That is, the lens frame 30 (and the lens G) can be moved to a desired position with high accuracy by appropriately controlling the current (applied voltage) flowing through the coil 60.
Here, since the cantilever spring 110 that is slidably contacted with the guide shaft 41 is employed as the resistance member, a dedicated arrangement space is not required, and the parts are integrated, the apparatus is downsized, and the like. Can also be achieved.

6 and 7 are a front view and a partial cross-sectional view showing still another embodiment of the lens driving device according to the present invention. This embodiment is the same as the embodiment shown in FIG. 1 to FIG. 3 described above except that a detection means for detecting the position of the lens frame 30 in the optical axis direction L is provided. The description is abbreviate | omitted and attached | subjected.
That is, in this apparatus, as shown in FIGS. 6 and 7, a magnetic sensor 210 provided on the cover plate 20 and a magnetized shaft 220 provided on the lens frame 30 as a magnetized member are used as detection means. Has been.

  As shown in FIGS. 6 and 7, the magnetic sensor 210 is fixed to an attachment piece 25 formed integrally with the cover plate 20. The attachment piece 25 is formed so as to extend in the radial direction substantially perpendicular to the straight line connecting the two guide shafts 41 and 42 and bend in the optical axis direction L, and the magnetic sensor 210 is magnetized from the outside in the radial direction. The magnetic sensor 210 is fixed so as to face the outer peripheral surface. Here, as the magnetic sensor 210, an MR element, a Hall element or the like is employed.

  As shown in FIGS. 6 and 7, the magnetized shaft 220 is magnetized by arranging a plurality of S poles and N poles in the optical axis direction L in this order. The magnetized shaft 220 is fitted in the fitting hole 38a of the arm portion 38 extending from the cylindrical portion 31 of the lens frame 30, and is oriented so that the magnetized pattern is aligned in the optical axis direction L. .

According to this, for example, high-frequency magnetization (for example, several KHz / movement amount) is applied to the magnetization shaft 220, the magnetization pattern is read by the magnetic sensor 210, voltage conversion is performed, and the number of pulses is counted. As a result, the relative position of the lens frame 30 can be recognized and driven and controlled. In addition, the magnetized shaft 220 is magnetized at a low frequency (for example, 0.5 Hz / amount of movement), the magnetized pattern is read by the magnetic sensor 210, and the voltage is converted. From the information (map) indicating the relationship, the absolute position of the lens frame 30 can be recognized and controlled.
Thus, by providing the detection means, the position of the lens frame 30 (and the lens G) can be detected in a non-contact manner, and the lens G can be driven and controlled with high accuracy.
Here, since the magnetic sensor 210 and the magnetized shaft 220 are arranged in one region at the four corners of the substantially rectangular R, it is possible to achieve the integration of parts and the miniaturization of the entire apparatus.

FIG. 8 shows a modification of the lens driving device shown in FIGS. 6 and 7. In this embodiment, the magnetic sensor 210 is fixed to the lens frame 30, and the magnetized member also serves as the guide shaft 220 ′. It is what I did.
That is, in this apparatus, the magnetic sensor 210 is fixed to an attachment piece 34 ′ extending from the fitting portion 34 of the lens frame 30. The guide shaft 220 ′ is magnetized by arranging a plurality of central regions in the optical axis direction L in the order of S and N poles, one end of the fixing hole 12 of the substrate 10 and the other end of the cover plate 20. The lens frame 30 is guided in the optical axis direction L by being fitted and fixed in the fixing holes 22 and slidably fitted in the fitting holes 34 a of the lens frame 30.
According to this, the drive control can be performed as described above, and since the magnetized member also serves as the guide shaft 220 ', the number of parts can be reduced despite the increased detection function, and the apparatus is simplified and miniaturized. (Smaller diameter and thinner).

9 and 10 are a front view and a partial cross-sectional view showing still another embodiment of the lens driving device according to the present invention. Since this embodiment is the same as the embodiment shown in FIGS. 6 and 7 except that the detection means is changed, the same components are denoted by the same reference numerals and the description thereof is omitted. .
That is, in this apparatus, as shown in FIGS. 9 and 10, as a detection means, a photosensor 300 provided on the cover 20 and a detected piece 39 provided on the lens frame 30 and detected by the photosensor 300 are provided. It has been adopted.

As shown in FIGS. 9 and 10, the optical sensor 300 is fixed to an attachment recess 26 formed integrally with the cover plate 20. The mounting recess 26 is formed so as to extend in a radial direction substantially perpendicular to a straight line connecting the two guide shafts 41 and 42 and to open toward the rear in the optical axis direction L. The optical sensor 300 is arranged in the optical axis direction L. It arrange | positions so that the to-be-detected piece 39 may be received from back. Here, as the optical sensor 300, a transmissive photo interrupter or the like having a light projecting element 300a and a light receiving element 300b that receives light emitted from the light projecting element 300a through the slit 300c is employed.
As shown in FIG. 10, the detection piece 39 is formed in a thin plate shape that protrudes radially outward from the cylindrical portion 31 of the lens frame 30 and extends forward in the optical axis direction L.

According to this, the position of the lens frame 30 can be detected with high accuracy in a non-contact manner by detecting the detected piece 39 with the optical sensor 300 (photo interrupter).
For example, since the amount of light received through the slit 300c changes according to the amount of entry of the detected piece 39, the analog component of the output of the optical sensor 300 is extracted from the amount of received light, and the relationship between the voltage prepared in advance and the amount of movement The absolute position of the lens frame 30 can be recognized from the information (map) indicating the drive control.
In addition, since the optical sensor 300 and the detected piece 39 are arranged in one region at the four corners of the substantially rectangular R, it is possible to achieve the integration of parts and the miniaturization of the entire apparatus.

In the above embodiment, the magnet 50 is provided on the lens frame 30 as a mover, and the coil 60 and the yoke 70 are provided on the base (cover plate 20) as a stator, but conversely, the coil and yoke are provided on the lens frame. It may be provided as a mover, and a magnet may be provided on the base as a stator.
In the said embodiment, although the case where the coil spring 100 was employ | adopted as an urging member was shown, it is not limited to this, You may employ | adopt another member as long as it exerts urging | biasing force.
Although the case where the cantilever spring 110 is employed as the resistance member has been described in the above embodiment, the present invention is not limited to this, and other members may be employed as long as they exert a resistance force.
In the above-described embodiment, the case where the magnetic sensor 210 and the magnetized members 220 and 220 ′, or the optical sensor 300 and the detected piece 39 are employed as the detection unit has been described. Other detection means may be employed as long as the position in the axial direction L can be detected.

  As described above, the lens driving device of the present invention achieves the simplification of the structure, the consolidation of parts, the reduction in size in the radial direction perpendicular to the optical axis (the reduction in diameter), the reduction in the thickness in the optical axis direction, and the like. Since the lens can be driven smoothly and with high accuracy in the optical axis direction, the lens of a mobile camera mounted on a portable information terminal device such as a mobile phone, a PDA, or a portable music player that is required to be downsized Of course, it can be applied as a driving device, and is also useful as a driving device for a lens optical system that is not particularly required to be downsized.

It is a front view which shows one Embodiment of the lens drive device which concerns on this invention. It is sectional drawing in E1-E1 in FIG. It is sectional drawing in E2-E2 in FIG. It is sectional drawing which shows other embodiment of the lens drive device which concerns on this invention. It is sectional drawing which shows other embodiment of the lens drive device which concerns on this invention. It is a front view which shows other embodiment of the lens drive device which concerns on this invention. It is a fragmentary sectional view in E3-E3 in FIG. It is sectional drawing which shows the modification of embodiment shown in FIG. It is a front view which shows other embodiment of the lens drive device which concerns on this invention. It is a fragmentary sectional view in E4-E4 in FIG.

Explanation of symbols

10 Substrate (base)
11 Openings 12 and 13 Fixing hole 20 Cover plate (base)
21 Openings 22 and 23 Fixing hole 24 Cylindrical portion 25 Mounting piece 26 Mounting recess 30 Lens frame G Lens L Optical axis direction 31 Cylindrical portions 32 and 33 Arm portion 34 Fitting portion 34 'Mounting piece 34a Fitting hole 35 Fitting portion 35a U-shaped recesses 36, 37 Annular recess 38 Arm 38a Fitting hole 39 Detected piece (detection means)
41, 42 Guide shaft 50 Magnet 60 Excitation coil 70 Yoke 71 Inner cylindrical portion 72 Outer cylindrical portion 100 Coil spring (biasing member)
110 Cantilever spring (resistance member)
210 Magnetic sensor (detection means)
220 Magnetized shaft (magnetized member, detection means)
220 'guide shaft (magnetized member, detection means)
300 Optical sensor (detection means)

Claims (12)

A base, a cylindrical lens frame for holding a lens, two guide shafts fixed to the base to guide the lens frame in the optical axis direction, an annularly formed coil, and an annular shape A lens driving device comprising: a magnet; and a yoke formed in a double cylindrical shape having a U-shaped cross section and an inner cylindrical portion and an outer cylindrical portion,
The magnet is provided on one of the lens frame and the base,
The coil and the yoke are provided on the other of the lens frame and the base,
The two guide shafts are arranged outside the magnet, coil, and yoke in a radial direction perpendicular to the optical axis,
The lens frame has a fitting portion that protrudes in the radial direction and is slidably fitted to the two guide shafts.
A lens driving device. The two guide shafts are arranged on or near a straight line perpendicular to the optical axis,
The lens driving device according to claim 1. The coil and the yoke are fixed to the base;
The magnet is fixed to the lens frame so as to define at least a part of an outer peripheral surface of the lens frame;
The lens frame has an annular recess that receives the inner cylindrical portion of the yoke in a non-contact manner on the radially inner side of the magnet.
The lens driving device according to claim 1. The magnet and the lens frame are molded in two colors using a resin material.
The lens driving device according to claim 3. A biasing member that biases the lens frame in one direction along the optical axis is provided.
The lens driving device according to claim 1, wherein The biasing member is a coil spring that is disposed coaxially around the guide shaft and exerts a biasing force between the base and the fitting portion of the lens frame.
The lens driving device according to claim 5. A resistance member is provided that exerts a resistance against the movement of the lens frame,
The lens driving device according to claim 1, wherein The resistance member is a cantilever spring having one end fixed to the lens frame and the other end slidably pressed on the outer peripheral surface of the guide shaft.
The lens driving device according to claim 7. Having detection means for detecting the position of the lens frame in the optical axis direction;
The lens driving device according to claim 1, wherein the lens driving device is a lens driving device. The detection means includes a magnetic sensor provided on one of the base and the lens frame, and a magnetized member provided on the other of the base and the lens frame and magnetized by being arrayed in the optical axis direction. ,
The lens driving device according to claim 9. The magnetic sensor is fixed to the lens frame,
The magnetized member also serves as the guide shaft;
The lens driving device according to claim 10. The detection means includes an optical sensor provided on the base, and a detected piece provided on the lens frame and detected by the optical sensor,
The lens driving device according to claim 9.

Images