JP2006047906A - Lens driving device and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact lens driving device capable of driving a lens in an optical axis direction, and to provide an imaging apparatus. <P>SOLUTION: The lens driving device is equipped with a stator which forms magnetic field in cylindrical shape, a rotor which has cylindrical shape coaxial to the stator and is driven to be rotated by the magnetic field formed by the stator, a lens holder which holds the lens so that the optical axis thereof may go along the axis of the cylindrical shape, a changing mechanism which changes the direction of force generated by driving and rotating the rotor to the direction going along the optical axis of the lens and transmits the force to the lens holder, and a rotation guide which regulates the position of the rotary shaft of the rotor by guiding the rotation of the rotor while coming into contact with both ends of the cylindrical shape of the rotor and is set so that regulation at either of both ends is more gentle than that at the other. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lens driving device that drives a lens in a direction along an optical axis, and an imaging device that acquires image data representing subject light.

  2. Description of the Related Art It is widely practiced to incorporate an imaging device that captures a subject and obtains a digital captured image in a small device such as a mobile phone or a PDA (Personal Digital Assistant). Since an imaging device is provided in a small device that is always carried around, it is possible to easily take a picture anytime without having to carry a digital camera or a video camera. In addition, these small devices are generally equipped with a data communication function using wireless or infrared rays in advance, and the captured images are immediately taken on the spot to other mobile phones, personal computers, etc. There is also an advantage that it can be sent to.

  However, since an imaging device built in a small device such as a mobile phone is considerably smaller than a normal digital camera, the size of components such as a lens and a charge coupled device (CCD) and the components are not limited. The storage space is greatly limited. For this reason, these small devices have insufficient shooting functions and image quality of captured images to be used as alternative devices for digital cameras. For obtaining images instead of memos, and for standby screens for mobile phones and the like. As in the case of obtaining an image, the use is often limited for shooting that does not require image quality.

  In recent years, small CCDs with high pixels and small lenses with high contrast have been developed in these respects, and the quality of captured images taken using small devices such as mobile phones and PDAs has rapidly increased. Is going on. In order to enhance the imaging function, which remains as a remaining issue, it is particularly desirable that these small devices are equipped with an autofocus function and a zoom function that are normally installed in digital cameras.

  The autofocus function and the zoom function are realized by moving a plurality of lenses in a direction along the optical axis in the imaging apparatus (hereinafter, the direction along the optical axis is referred to as the front-rear direction). In a digital camera, a digital video camera, or the like, as a lens driving method, a method using rotation of a DC motor or a stepping motor, a method using compression / expansion of a piezoelectric element, and the like are known. When these methods are applied to a small device such as a mobile phone, a cylindrical hollow rotor that surrounds the outer periphery of the lens barrel holding the lens in terms of downsizing of the device and accuracy of lens movement control. It is considered preferable to use a hollow stepping motor that rotates the stator by applying a pulse current to the stator that surrounds the outer periphery of the hollow rotor.

As a lens driving method to which such a hollow stepping motor is applied, for example, a method of driving the lens barrel in a direction along the optical axis via a moving mechanism such as a cam mechanism between the lens barrel and the rotor ( For example, see Patent Literature 1, Patent Literature 2, and Patent Literature 3), a method of moving a lens barrel with the rotor itself (for example, Patent Literature 4, Patent Literature 5, Patent Literature 6), a lens barrel and a rotor. An integration method (for example, Patent Document 7) has been proposed.
JP-A-56-147132 JP 59-109006 JP 59-109007 JP 60-415 JP-A-60-416 JP 60-417 Japanese Patent Laid-Open No. 62-195615

  Here, the method described in the above-mentioned patent document is devised for the purpose of being applied to a digital camera or the like of a normal size, and these methods are directly applied to an imaging apparatus that is much smaller than a digital camera. When trying to do so, there is a problem that the lens is not driven because it is strongly influenced by friction and the like as the apparatus is downsized.

  In view of the above circumstances, an object of the present invention is to provide a small lens driving device and an imaging device that can drive a lens along an optical axis.

The lens driving device of the present invention that achieves the above object is a lens driving device that drives a lens in a direction along the optical axis.
A stator having a cylindrical shape and forming a magnetic field in the cylindrical shape;
A rotor positioned within the cylindrical shape of the stator and having a cylindrical shape coaxial with the cylindrical shape, the rotor being driven to rotate relative to the stator by a magnetic field formed by the stator;
A lens holder positioned further inside the cylindrical shape of the rotor and holding the lens so that the optical axis is along the cylindrical axis;
A conversion mechanism that converts the direction of the force due to the rotational drive of the rotor into a direction along the optical axis of the lens and transmits it to the lens holder;
At both ends of the cylindrical shape of the rotor, the position of the rotating shaft of the rotor is regulated by physically contacting the cylindrical shape and guiding the rotation of the rotor. And a rotating guide that is looser than the restriction by physical contact at the other end.

  According to the lens driving device of the present invention, both ends of the cylindrical shape of the rotor are in physical contact with the rotating guide with different accuracy. Therefore, the position of the rotating shaft is reliably defined on the side of the rotor that is in contact with the rotation guide with high accuracy, and the rotor rotates smoothly due to the margin on the side that is in contact with the rotation guide with low accuracy. Even when the present invention is applied to an imaging device that is much smaller than a digital camera, the lens can be driven along the optical axis.

  In the lens driving device of the present invention, it is preferable that the lens holder includes an elastic member that urges the lens holder toward the other end of the cylindrical ends.

  The lens holder can be smoothly driven by using the biasing force by the elastic member in addition to the driving force by the rotation of the rotor. At this time, rattling of the rotating shaft of the rotor can be avoided by urging the lens holder toward the side in contact with the rotation guide with high accuracy.

Further, an image pickup apparatus of the present invention that achieves the above object is an image pickup apparatus that drives a lens in a direction along an optical axis, forms an image of subject light with the lens, and acquires image data representing the subject light.
A lens,
A stator having a cylindrical shape and forming a magnetic field in the cylindrical shape;
A rotor positioned within the cylindrical shape of the stator and having a cylindrical shape coaxial with the cylindrical shape, the rotor being driven to rotate relative to the stator by a magnetic field formed by the stator;
A lens holder that is positioned further inside the cylindrical shape of the rotor and holds the lens so that the optical axis is along the cylindrical axis;
A conversion mechanism that converts the direction of the force due to the rotational drive of the rotor into a direction along the optical axis of the lens and transmits it to the lens holder;
At both ends of the cylindrical shape of the rotor, the position of the rotating shaft of the rotor is regulated by physically contacting the cylindrical shape and guiding the rotation of the rotor. A rotating guide that is looser than the regulation by physical contact at the other end
An image pickup device is provided that includes subject light that has passed through the lens and formed on the surface to generate an image signal representing the subject light.

  According to the imaging apparatus of the present invention, the lens can be smoothly driven along the optical axis even when mounted on a small device such as a mobile phone.

  Note that only the basic form of the imaging apparatus according to the present invention is shown here, but this is only for avoiding duplication, and the imaging apparatus according to the present invention is not limited to the above basic form. Various forms corresponding to the respective forms of the lens driving device described above are included.

  ADVANTAGE OF THE INVENTION According to this invention, the small lens drive device which can drive a lens to the direction along an optical axis, and an imaging device can be provided.

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

  FIG. 1 is an external perspective view of an imaging apparatus to which an embodiment of the present invention is applied.

  The imaging device 1 is a small imaging device mounted on a mobile phone or the like, and focuses a subject by driving a plurality of lenses in a direction along the optical axis (hereinafter, this direction is referred to as a front-rear direction). An autofocus function is provided. The imaging device 1 has an external appearance in which a cylindrical stator 30 is sandwiched between a front cover 10 and a rear cover 40. Inside the stator 30, a magnet and a plurality of lenses described later are provided. A held lens holder 20 or the like is disposed. The stator 30 corresponds to an example of a stator according to the present invention.

  FIG. 2 is a cross-sectional view of the imaging device 1 shown in FIG. 1 cut along a plane passing through the straight line AA ′.

  FIG. 2 shows the front cover 10, the rear cover 40, the stator 30, and the lens holder 20 that are also shown in FIG. 1, and further includes a first lens 21, a second lens 22, a third lens 23, a magnet 50, A rotating body 51, a CCD 60, and the like are shown.

  The lens holder 20, the magnet 50, and the rotating body 51 have a cylindrical shape coaxial with the stator 30. The magnet 50, the rotating body 51, and the lens holder 20 are arranged inside the stator 30 in this order from the side close to the stator 30. ing. The stator 30 and the magnet 50 constitute a stepping motor. When a pulse current is applied to the stator 30, the magnet 50 is rotated by the number of rotations corresponding to the pulse current. A combination of the magnet 50 and the rotating body 51 corresponds to an example of a rotor according to the present invention, and the lens holder 20 corresponds to an example of a lens holder according to the present invention.

  Here, the description of FIG. 2 is temporarily interrupted, and the stator 30 and the magnet 50 will be described in detail with reference to FIG.

  FIG. 3 is a diagram showing the stator 30 and the magnet 50.

  The stator 30 is composed of two layers of coil parts, an upper coil part 30a and a lower coil part 30b. Since the upper coil portion 30a and the lower coil portion 30b have the same configuration, the description of the configuration of the lower coil portion 30b is omitted, and only the configuration of the upper coil portion 30a will be described.

  The upper coil portion 30a is formed to be surrounded by a cylindrical shape by an upper coil cover 32 and a lower coil cover 33, and a coil 31 made of a wound conductive wire is stored in the inside surrounded by the cover. . The upper coil cover 32 and the lower coil cover 33 are provided with teeth 32a and 33a arranged so as to engage with each other alternately inside the cylindrical shape. There is a gap between the teeth 32a and the teeth 33a.

  A pulse current is alternately applied to the coil 31 of the upper coil portion 30a and the coil 31 of the lower coil portion 30b. When a pulse current is applied, magnetic field lines are generated in the coil 31, and the magnetic field lines are guided to the inside of the cylindrical shape by the upper coil cover 32 and the lower coil cover 33. When the introduced magnetic field lines reach the teeth 32a and 33a, the magnetic field lines once enter the air and cross the gap. As a result, one of the teeth 32 a and 33 a arranged so as to mesh with each other is an N pole, and the other is an S pole, and magnetic fields of the N pole and the S pole are alternately formed along the cylindrical inner periphery of the stator 30. .

  For example, the magnet 50 is passed through a ring-shaped head in which N poles and S poles are alternately formed along the inner periphery, thereby alternately alternating N and S poles along the outer periphery of the cylindrical shape. It is a permanent magnet with a magnetic pole. The magnet 50 is rotationally driven with respect to the stator 30 by a repulsive force and an attractive force with a magnetic field formed by the stator 30.

  The rotation drive of the magnet 50 will be described.

  The magnet 50 has 48 poles, and each of the upper coil portion 30a and the lower coil portion 30b has 48 teeth. Further, the position of the teeth of the upper coil portion 30a and the position of the teeth of the lower coil portion 30b are shifted by half of the teeth. When a pulse current is applied to the stator 30 as will be described later, the magnet 50 rotates with one pole as one step and rotates once in 48 steps.

  When rotating the magnet 50 in the forward direction, by repeating energization in the order of the forward direction of the upper coil portion 30a, the forward direction of the lower coil portion 30b, the reverse direction of the upper coil portion 30a, and the reverse direction of the lower coil portion 30b, The magnet 50 can be reliably rotated in the forward direction. Further, by repeating energization in the order of the forward direction of the upper coil portion 30a, the reverse direction of the lower coil portion 30b, the reverse direction of the upper coil portion 30a, and the forward direction of the lower coil portion 30b, the magnet 50 is rotated in the reverse direction. be able to.

  This is the end of the description of FIG. 3, and the description will return to FIG.

  A rotating body 51 shown in FIG. 2 is bonded to the inside of the magnet 50 and is rotated as the magnet 50 rotates. A spiral groove 51 a is provided on the inner surface of the rotating body 51, and the spiral groove 51 a meshes with a spiral groove 20 a (described later) provided on the outer surface of the lens holder 20.

  The lens holder 20 holds lenses arranged in the order of the first lens 21, the second lens 22, and the third lens 23 from the side close to the front cover 10. The first lens 21, the second lens 22, and the third lens 23 satisfy the following conditions.

  First, in this example, the first lens 21 is made of a glass material, and has a meniscus shape having a positive power with a convex surface (hereinafter referred to as a surface) on the front side (side near the front cover 10). .

  The second lens 22 is made of a plastic material. In this example, the second lens 22 has a meniscus shape having a negative power with an aspherical back surface and a concave surface.

  The third lens 23 is made of a plastic material, and both surfaces of the front and back surfaces are aspherical, and the back surface is a concave shape near the optical axis and has a negative power shape.

Further, if the paraxial focal length of the entire lens system is f, the paraxial focal length of the third lens 23 is f3, the radius of curvature of the surface of the first lens 21 is R1, and the half angle of view at the maximum image height is θ,
0.6 <R1 / f <0.8 (1)
-1.0 <f3 / f <0 (2)
0.60 <tan θ <0.70 (3)
Meet.

  By applying the first lens 21, the second lens 22, and the third lens 23 that satisfy the above conditions, a compact and highly accurate lens group can be configured.

  Further, a convex portion 20 b extending in the front-rear direction is provided in a space on the side of the first lens 21 of the lens holder 20, and an outer surface of a portion holding the second lens 22 and the third lens 23. Is provided with a spiral groove 20a.

  A mechanism for driving the lens holder 20 in the front-rear direction will be described.

  When a pulse current is applied to the stator 30, the rotating body 51 is rotated once every 48 steps as the magnet 50 rotates. The spiral groove 51a of the rotating body 51 is provided two more times (= 96 steps) than the spiral groove 51a of the lens holder 20, and the lens holder 20 can move by 96 steps.

  The rotational force of the rotating body 51 is converted into a force in the front-rear direction by the spiral groove 51a and the spiral groove 20a. The converted force in the front-rear direction is transmitted to the lens holder 20, and the lens holder 20 is driven in the front-rear direction. In this embodiment, the lens holder 20 moves about 1.25 mm in the front-rear direction with a full stroke (= 96 steps), and moves about 13 μm in the front-rear direction in one step. That is, in this imaging device 1, the lens position can be controlled in units of 13 μm. A combination of the spiral groove 51a and the spiral groove 20a corresponds to an example of a conversion mechanism according to the present invention.

  A spring 24 is attached to the rear side of the lens holder 20 (side closer to the rear cover 40). The spring 24 reinforces the driving force of the lens holder 20 by urging the lens holder 20 in the forward direction (the direction from the rear cover 40 toward the front cover 10). The spring 24 corresponds to an example of the elastic member referred to in the present invention.

  The front cover 10 and the rear cover 40 shown in FIG. 2 are connected by screws (not shown).

  The front cover 10 is provided with a concave portion 10 a that extends in the front-rear direction and fits with the convex portion 20 b at a portion corresponding to the convex portion 20 b of the lens holder 20. The rotational force of the magnet 50 is transmitted to the lens holder 20 by the spiral groove 51a and the spiral groove 20a, but when the movement of the lens holder 20 in the rotation direction is not restricted, the lens holder 20 moves in the front-rear direction while rotating. Therefore, the image may be shifted due to the eccentricity of the lens. Such a rotation of the lens holder 20 is prevented by fitting the convex portion 20b of the lens holder 20 and the concave portion 10a of the front cover 10 to each other. Further, the front cover 10 is provided with a front rotation guide 10b that contacts the front portion of the rotating body 51 and guides the rotation of the rotating body 51, and the rotating body 51 and the magnet 50 are provided by the front rotation guide 10b. Movement in the left-right direction at the front portion of the is restricted.

  The rear cover 40 is provided with a rear rotation guide 40a that comes into contact with the rear portion of the rotator 51. The rear rotation guide 40a restricts the movement of the rear portion of the rotator 51 and the magnet 50 in the left-right direction. Yes. A combination of the front rotation guide 10b of the front cover 10 and the rear rotation guide 40a of the rear cover 40 corresponds to an example of the rotation guide referred to in the present invention.

  Further, the rear cover 40 holds the low-pass filter 41 and the CCD 60.

  The subject light that has passed through the first lens 21, the second lens 22, and the third lens 23 is received by the CCD 60 through the low-pass filter 41. In the low-pass filter 41, unnecessary fine spatial frequency components included in the subject light are leveled. By using the low-pass filter 41, problems such as pseudo colors and moire can be reduced.

  The subject light that has passed through the low-pass filter 41 is received by the CCD 60, and image data representing the subject is generated. The CCD 60 corresponds to an example of an imaging mechanism according to the present invention.

  In the imaging apparatus 1 as described above, the autofocus function is realized by the following procedure. In the following description, it is assumed that the lens holder 20 moves forward by applying a forward pulse current to the stator 30.

  First, subject light is roughly read by the CCD 60, and low-resolution data representing the subject light is generated. This low resolution data is transmitted to a CPU such as a mobile phone provided with the imaging device 1.

  Subsequently, a forward pulse current for moving the lens holder 20 by one step is supplied to the stator 30.

  When a pulse current is applied to the stator 30, the magnet rotates by one step, and the rotating body 51 is rotated with the rotation of the magnet. The rotational force of the rotating body 51 is converted into a forward force and transmitted to the lens holder 20, and the lens holder 20 moves about 13 μm in the forward direction.

  When the lens holder 20 moves, the subject light is read again by the CCD 60 and low resolution data is generated. This low resolution data is also transmitted to a CPU such as a mobile phone provided with the imaging device 1.

  The CPU detects the contrast of each of the two low-resolution data transmitted from the CCD 60, and determines which of the detected contrasts is greater. When the contrast of the previous low resolution data is larger, a reverse pulse current for returning the lens holder 20 by one step backward is energized to the stator 30 and the contrast of the subsequent low resolution data is larger. In this case, a forward pulse current that moves the lens holder 20 forward one step further is supplied to the stator 30.

  As described above, the process of detecting the contrast by moving the lens holder 20 is continued for up to 96 steps until the magnitude of the contrast of the previous low-resolution data and the contrast of the subsequent low-resolution data are reversed. When the magnitudes of these contrasts are reversed, the stator 30 is energized with a pulse current in a direction opposite to the direction energized immediately before, and the lens holder 20 is returned by one step. The position of the lens holder 20 at this time is an in-focus position where the contrast is maximized.

  The imaging device 1 is basically configured as described above.

  Here, in the imaging device 1, the front rotation guide 10 b of the front cover 10 and the rear rotation guide 40 a of the rear cover 40 come into contact with the rotation body 51 to guide the rotation of the rotation body 51 and the magnet 50 and rotate. The movement of the body 51 and the magnet 50 in the left-right direction is restricted. However, since the image pickup apparatus 1 is mounted on a mobile phone or the like, the entire apparatus is downsized, and if both the front rotation guide 10b and the rear rotation guide 40a come into contact with each other, the friction is caused. The rotating body 51 and the magnet 50 will not rotate due to the strong influence of the above. Below, the contact intensity | strength with the rotary body 51 and the front rotation guide 10b and the back rotation guide 40a is demonstrated.

  FIG. 4 is a simplified cross-sectional view when the imaging device 1 is cut along a plane passing through the optical axis O of the lens (a plane passing through the straight line AA ′ shown in FIG. 1).

As shown in FIG. 4, the rotating body 51 contacts with the front rotation guide 10b of the front cover 10 in the front portion P _1, in contact with the rotating guide 40a of the rear cover 40 at the rear portion P _2.

At this time, the inner diameter of the rotating body 51 in the front portion P ₁ and Fai1_1, the outer diameter of the pre-rotation guide 10b of the front portion P ₁ and Fai1_2.

Further, the inner diameter of the rotating body 51 at the rear portion P ₂ and? 2_1, the outer diameter of the post-rotation guide 40a at the rear portion P ₂ and? 2_2.

  By changing these lengths φ1_1 to φ2_2, the contact strengths of the rotating body 51 with the front rotating guide 10b and the rear rotating guide 40a are changed, and the rotating condition of the rotating body 51 and the magnet 50 is confirmed.

  Table 1 shows an example of the lengths of φ1_1 to φ2_2 in the imaging device 1 shown in FIG.

In Example 1, Example 2, and Comparative Example 3, commonly, the rotating body 51, the front portion P ₁ of the inner diameter Fai1_1, and towards the rear portion P ₂ of the inner diameter φ2_1 increases are tolerances manufacture Thus, the front cover 10 and the rear cover 40 are manufactured in such a manner that an error is allowed in such a manner that the outer diameter φ1_2 of the front rotation guide 10b and the outer diameter φ2_2 of the rear rotation guide 40a become smaller.

In the first embodiment, the inner diameter φ1_1 (8.20 mm, maximum tolerance 0.022 mm) of the rotating body 51 in the front portion P ₁ and the outer diameter φ1_2 (8.20 mm, maximum tolerance −0.036 mm) of the front rotation guide 10b. However, they are not completely equal due to production errors, but they are quite close (φ1_1-φ1_2 is a maximum of 0.058 mm), and the rotating body 51 is tightly restricted by the front rotation guide 10b.

Further, the inner diameter φ2_1 (8.67 mm, maximum tolerance 0.02 mm) of the rotating body 51 in the rear portion P ₂ is designed to be larger than the outer diameter φ2_2 (8.60 mm, maximum tolerance −0.03 mm) of the rear rotation guide 40a. (Φ2_1−φ2_2 is 0.07 mm at the minimum and 0.12 mm at the maximum), and the rotating body 51 is loosely regulated by the rear rotation guide 40a.

  In the first embodiment, the movement of the rotating body 51 in the left-right direction is surely restricted by the front rotating guide 10b, and the rotating body 51 and the magnet 50 are smoothly moved by the margin between the rear rotating guide 40a and the rotating body 51. It is rotated. Therefore, according to the imaging apparatus of the first embodiment, the lens can be smoothly driven in the direction along the optical axis.

  Further, as shown in FIG. 2, a spring 24 is attached to the lens holder 20 to reinforce the driving force of the lens. The spring 24 urges the lens holder 20 toward the front side in which the movement of the rotating body 51 in the left-right direction is restricted, so that the lens holder 20 is prevented from shaking in the left-right direction and the lens is more smoothly moved. Can be driven.

In Example 2 shown in Table 2, the inner diameter φ1_1 (8.20 mm, maximum tolerance 0.02 mm) of the rotating body 51 in the front portion P ₁ is equal to the outer diameter φ1_2 (8.17 mm, maximum tolerance −0) of the front rotation guide 10b. (.Phi.1_1-.phi.1_2 is 0.03 mm at the minimum and 0.08 mm at the maximum), and the rotating body 51 is loosely regulated by the front rotation guide 10b.

In the rear part P ₂ , the inner diameter φ2_1 (8.70 mm, maximum tolerance 0.22 mm) of the rotating body 51 and the outer diameter φ2_2 (8.70 mm, maximum tolerance −0.036 mm) of the rear rotation guide 40a are quite close to each other ( φ2_1-φ2_2 is 0.058 mm at the maximum), and the rotating body 51 is tightly restricted by the rear rotation guide 40a.

  In the second embodiment, contrary to the first embodiment, the movement of the rotating body 51 in the left-right direction is reliably restricted by the rear rotation guide 40a, and the rotation between the front rotation guide 10b and the rotating body 51 is performed by the margin. The body 51 and the magnet 50 are smoothly rotated. Therefore, also in the imaging apparatus according to the second embodiment, the lens can be smoothly driven in the direction along the optical axis.

  In the second embodiment, the spring 24 shown in FIG. 2 biases the lens holder 20 toward the front side opposite to the rear side where the movement of the rotating body 51 in the left-right direction is restricted. If there is too much room between 10b and the rotator 51, the lens holder 20 will move in the left-right direction. Therefore, in the second embodiment, the clearance between the rear rotation guide 40a and the rotating body 51 in the first embodiment (φ2_1−φ2_2 is 0.12 mm at the maximum) between the front rotating guide 10b and the rotating body 51. A slightly smaller margin (φ1_1−φ1_2 is 0.08 mm at the maximum) is provided.

In the comparative example shown in Table 1, the inner diameter of the rotating body 51 in the front portion P ₁ Fai1_1 and (8.20 mm, a maximum tolerance 0.022 mm), outer diameter φ1_2 (8.20mm before rotation guide 10b, a maximum tolerance -0 0.036 mm) (φ2_1-φ1_2 is 0.058 mm at the maximum), and the rotating body 51 is tightly regulated by the front rotation guide 10b.

In the rear portion P ₂ , the inner diameter φ2_1 (8.20 mm, maximum tolerance 0.022 mm) of the rotating body 51 and the outer diameter φ2_2 (8.20 mm, maximum tolerance −0.036 mm) of the rear rotation guide 40a are also present. It is quite close (φ2_1-φ2_2 is 0.058 mm at the maximum), and the rotating body 51 and the post-rotation guide 40a are also in tight contact.

  The imaging device 1 shown in FIGS. 2 and 4 is mounted on a mobile phone or the like, and is greatly affected by friction and the like because the entire device is downsized. In the case of the comparative example, in addition to the influence of the friction described above, the rotating body 51 is tightly regulated by both the front rotating guide 10b and the rear rotating guide 40a, so the rotating body 51 and the magnet 50 do not rotate, and the lens is not at all. Did not drive.

  Contrary to the comparative example, when both the front rotation guide 10b and the rear rotation guide 40a are loosely brought into contact with the rotating body 51, the lens is driven smoothly, but the rotating body 51 and the magnet 50 are likely to rattle. It is considered that the lens is shaken in the left-right direction and image blurring occurs in the photographed image.

  As described above, when one of the front rotation guide 10b and the rear rotation guide 40a is brought into contact with the rotator 51 more loosely than the other, the lens is smoothly driven while avoiding a problem in which image blurring occurs in the captured image. be able to.

  Here, the example of the front rotation guide 10b and the rear rotation guide 40a contacting the front and rear ends of the rotating body 51 has been described above. However, the rotation guide referred to in the present invention contacts the front and rear ends of the magnet 50. May be.

  In the above description, the stepping motor that controls the rotation of the rotor by applying a pulse current to the stator has been described. However, the motor for driving the lens holder in the present invention may be a DC motor or the like. Good.

  Moreover, although the example which applies a helical groove | channel as a conversion mechanism was demonstrated above, the conversion mechanism said to this invention may be a cam groove, a cam pin, etc., for example.

  In the above description, the example in which the lens holder is driven to realize the autofocus function has been described. However, the lens driving device and the imaging device of the present invention may be configured to realize a zoom function, for example. Both the function and the auto focus function may be realized.

1 is an external perspective view of an imaging apparatus to which an embodiment of the present invention is applied. It is sectional drawing when cut | disconnecting the imaging device 1 shown in FIG. 1 in the surface which passes along straight line AA '. It is a figure which shows the stator 30 and the magnet 50. FIG. FIG. 3 is a simplified cross-sectional view when the imaging device 1 is cut along a plane passing through the optical axis of a lens.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Imaging device 10 Front cover 10a Concave part 11 Column 20 Lens holder 20a Spiral groove 20b Convex part 21 1st lens 22 2nd lens 23 3rd lens 30 Stator 30a Upper coil part 30b Lower coil part 31 Coil 32 Upper coil cover 33 Lower coil Cover 32a, 33a Teeth 40 Rear cover 41 Low pass filter 50 Magnet 51 Rotating body 51a Spiral groove 60 CCD

Claims (3)

In the lens driving device that drives the lens in the direction along the optical axis,
A stator having a cylindrical shape, and forming a magnetic field in the cylindrical shape;
A rotor positioned within the cylindrical shape of the stator and having a cylindrical shape coaxial with the cylindrical shape, the rotor being driven to rotate relative to the stator by a magnetic field formed by the stator;
A lens holder that is positioned further inside the cylindrical shape of the rotor and holds the lens so that the optical axis is along the cylindrical axis;
A conversion mechanism that converts the direction of the force generated by the rotational drive of the rotor into a direction along the optical axis of the lens and transmits the direction to the lens holder;
Physical contact at one of the two ends of the rotor that regulates the position of the rotation axis of the rotor by guiding the rotation of the rotor by physically contacting the cylindrical shape at both ends of the cylindrical shape of the rotor. A lens driving device comprising: a rotation guide that is looser than the restriction by physical contact at the other end of the both ends.   The lens driving device according to claim 1, further comprising an elastic member that biases the lens holder toward the other end of the cylindrical shape. In an imaging device that drives a lens in a direction along the optical axis, forms an image of subject light with the lens, and obtains image data representing the subject light.
The lens;
A stator having a cylindrical shape, and forming a magnetic field in the cylindrical shape;
A rotor positioned within the cylindrical shape of the stator and having a cylindrical shape coaxial with the cylindrical shape, the rotor being driven to rotate relative to the stator by a magnetic field formed by the stator;
A lens holder that is located further inside the cylindrical shape of the rotor and holds the lens so that the optical axis is along the cylindrical axis;
A conversion mechanism that converts the direction of the force generated by the rotational drive of the rotor into a direction along the optical axis of the lens and transmits the direction to the lens holder;
Physical contact at one of the two ends of the rotor that regulates the position of the rotation axis of the rotor by guiding the rotation of the rotor by physically contacting the cylindrical shape at both ends of the cylindrical shape of the rotor. The rotation guide is more loose than the regulation by physical contact at the other end of the both ends,
An imaging apparatus comprising: an imaging element that forms an image signal representing the subject light by imaging the subject light that has passed through the lens on the surface thereof.

Images