JP5238991B2 - Lens drive device - Google Patents

Description

  The present invention relates to a lens driving device that forms an image of a subject by driving a lens in the direction of an optical axis.

  In recent years, as camera-equipped mobile phones equipped with cameras have become popular, opportunities for photographing various subjects using the mobile phones have increased. For example, you can shoot a subject that is far away from the camera lens, such as a friend or landscape (normal shooting), or a subject that is close to the camera lens, such as a bus timetable or petals (close-up shooting) There is a case.

  In close-up photography (macro photography), the lens position of the camera needs to be slightly closer to the subject side than the lens position during normal photography. For this reason, this type of photographic lens system includes a drive mechanism that drives the lens to move in the direction of the optical axis, so that the lens can be moved in the direction of the optical axis by driving the drive mechanism by switching a switch. (For example, refer to Patent Document 1).

  The lens driving device disclosed in Patent Document 1 includes a cylindrical moving lens body, a driving mechanism that moves the moving lens body in the optical axis direction, and a fixed body that supports the moving lens body so as to be movable in the optical axis direction. And a restricting means (plate spring) for restricting the movement of the movable lens body. The drive mechanism has a magnet and a coil. In such a configuration, an electric force is supplied to the coil to generate an electromagnetic force, while a restricting force that opposes the electromagnetic force is generated by the restricting means, and the size of both is adjusted, thereby making the moving lens body a desired one. Can be stopped in position.

  Here, the fixed body includes a holder that holds the rear end surface (the surface opposite to the subject side) of the moving lens body via a leaf spring. The lens barrel (lens barrel) incorporated in the moving lens body is generally incorporated after the moving lens body is attached to the holder for reasons such as dust and scratches being easily attached to the lens. Specifically, the lens barrel may be inserted (screwed) from the subject side to the moving lens body attached to the holder, or conversely, the lens barrel may be inserted (screwed) from the imaging element side opposite to the subject side. )In some cases.

  Therefore, an opening is formed in the center of the holder to allow the reflected light from the subject that has passed through the lens to enter the image sensor. The inner diameter of this opening is the distance from the lens barrel to the moving lens body. In order to be able to be inserted, it was necessary to have a size larger than the inner diameter of the moving lens body (that is, the outer diameter of the lens barrel).

JP 2007-94364 A

  However, when the inner diameter of the opening becomes larger than the outer diameter of the lens barrel, when the lens barrel is attached to the moving lens body (when screwed), the generated sliding powder passes through the opening of the holder and passes through the glass filter or image sensor. There is a risk of falling off (image sensor). If the sliding powder remains attached to the glass filter or the image sensor (image sensor), the shadow is reflected, leading to a video defect, which in turn causes a problem of image quality degradation.

  The present invention has been made in view of the above points, and an object of the present invention is to prevent sliding powder that may be generated when a lens barrel is attached to a moving lens body from adhering to an imaging element or the like. The object is to provide a lens driving device.

  In order to solve the above problems, the present invention provides the following.

(1) A lens having a cylindrical movable body that holds a lens and is movable in the optical axis direction, a support that supports the movable body, and a magnetic drive mechanism that drives the movable body in the optical axis direction In the driving device, the support is formed with an opening through which reflected light from a subject that has passed through the lens is incident on the imaging device, and the moving body includes a lens barrel in which a lens is incorporated, and the lens. A sleeve for holding a barrel, and the inner diameter of the sleeve is larger than the inner diameter of the opening, and the inner peripheral surface of the sleeve extends in the radial direction in the vicinity of the end of the support on the opening side. The lens driving device according to claim 1, wherein the lens barrel is inserted from the subject side of the sleeve, and a convex portion protruding toward the movable body is formed on the periphery of the opening.

  According to the present invention, in the lens driving device having the moving body, the support body, and the magnetic drive mechanism, the support body is formed with the opening for allowing the reflected light from the subject that has passed through the lens to enter the imaging device. The inner diameter of the moving body described above is larger than the inner diameter of the opening, and a convex portion protruding toward the moving body is formed on the periphery of the opening. Even if sliding powder is generated when it is attached to the substrate, the sliding powder is received by the support without passing through the opening. In addition, since the protrusions that protrude toward the moving body are formed at the periphery of the opening, it is possible to prevent the sliding powder received by the support from dropping off from the opening to the glass filter or the image sensor. Can do. Therefore, it is possible to prevent the sliding powder from adhering to the glass filter and the image pickup device, and thus, it is possible to prevent image defects and prevent image quality deterioration.

  According to the lens driving device of the present invention, even when sliding powder is generated when the lens barrel is attached to the moving body, the sliding powder adheres to the imaging element or the like through the opening of the support. As a result, it is possible to prevent a video defect and, in turn, image quality deterioration.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

[Machine configuration]
FIG. 1 is a perspective view showing an external configuration of a lens driving device 1 according to an embodiment of the present invention. FIG. 2 is an exploded perspective view showing a mechanical configuration of the lens driving device 1 according to the embodiment of the present invention.

  1 and 2, the lens driving device 1 includes a yoke 11, a cover 12, a sleeve 13, a first plate spring 14, a second plate spring 15, a wire spring 16, a magnet 17, The coil 18 (the first coil 181 and the second coil 182) and the holder 19 are provided.

  Note that the illustration of a lens barrel (lens barrel) incorporating a lens is omitted. The lens driving device 1 also moves the sleeve 13 along the direction of the optical axis L in the A direction (front side) approaching the subject (imaging target) and the B direction (rear side) approaching the opposite side (image side) from the subject. (See FIG. 1). The sleeve 13 holding a lens barrel (not shown as described above) in which one or more lenses are incorporated is configured to be movable in the direction of the optical axis L together with the wire spring 16 and the like. It corresponds to an example of “moving body”. The holder 19 corresponds to an example of a “support” that supports the sleeve 13 and the like so as to be movable in the direction of the optical axis L via the first plate spring 14 and the second plate spring 15. The sleeve 13 and the like are driven in the direction of the optical axis L by a “magnetic drive mechanism” including a coil 18 and a magnet 17.

  The yoke 11 is made of a ferromagnetic plate such as a steel plate. Further, the yoke 11 is exposed at the front and side surfaces of the lens driving device 1, and a circular incident window 111 is formed at the center of the yoke 11 for taking reflected light from the subject into the lens. On the other hand, the cover 12 is attached to the yoke 11, and a circular incident window 121 is formed at the center of the cover 12 for taking reflected light from the subject into the lens.

  The coil 18 includes a first coil 181 and a second coil 182, which are arranged in two stages in the direction of the optical axis L, both of which are annular. Then, it is wound around the outer peripheral surface of the sleeve 13 at a predetermined interval. In addition, eight magnets 17 are arranged in two stages in the optical axis direction. The magnets 17 of each stage are arranged such that the front magnet 17 is against the first coil 181 and the rear magnet 17 is the first. The two coils 182 are opposed to each other on the outer peripheral side, and are fixed to four corners of the inner peripheral surface of the yoke 11 whose outer shape is substantially rectangular as shown in FIG.

  In the present embodiment, the magnet 17 is magnetized to poles whose inner surface and outer surface are different from each other. For example, the four magnets 17 arranged on the front side are magnetized with the N pole on the inner surface, the outer surface is magnetized with the S pole, and the four magnets 17 arranged on the rear side have an S inner surface. The pole is magnetized and the outer surface is magnetized to the N pole.

  The first plate spring 14 and the second plate spring 15 are both formed from a thin metal plate and have the same thickness in the direction of the optical axis L.

  Further, as shown in FIG. 2, the first leaf spring 14 is attached to the front end surface of the sleeve 13 in the optical axis direction, and the second leaf spring 15 is attached to the rear end surface of the sleeve 13 in the optical axis direction. .

  In the present embodiment, as shown in FIG. 2, the first leaf spring 14 and the second leaf spring 15 are not labeled, but the arcuate sleeve side mounting portion and the spacer 12 are respectively attached. A spacer-side attachment portion to be attached, and an arm portion that is formed between the sleeve-side attachment portion and the spacer-side attachment portion and restricts (bias) movement of the sleeve 13 in the optical axis direction. The part is fixed to the spacer 12 or the holder 19 using welding, adhesion, or both.

  The second leaf spring 15 is composed of two electrically separated spring pieces, and serves as a medium for supplying current from the external power source to the coil 18. The spring end is electrically connected to the other spring piece. The second leaf spring 15 is attached to the rear end surface of the sleeve 13 and attached to the holder 19. The holder 19 holds an image sensor (not shown) on the image side.

  Since the yoke 11 is larger than the dimension in the optical axis direction of the region where the first coil 181 and the second coil 182 are arranged, and the dimension in the optical axis direction of the magnet 17, the front magnet 17. Leakage flux from the magnetic path configured between the first coil 181 and the magnetic path configured between the rear magnet 17 and the second coil 182 can be reduced. As a result, the linearity between the amount of movement of the sleeve 13 and the current flowing through the first coil 181 and the second coil 182 can be improved.

  The lens driving device 1 includes an annular wire spring 16. The wire spring 16 applies a biasing force in the direction of the optical axis L to the sleeve 13 by a magnetic attractive force acting between the wire spring 16 and the magnet 17. For this reason, it is possible to prevent the moving body (sleeve 13 or the like) from being displaced by its own weight when the coil is not energized, and as a result, the moving body (sleeve 13 or the like) can be maintained in a desired posture. Yes.

  Here, the lens driving device 1 according to the present embodiment is characterized by the opening 19 a (see FIG. 2) formed in the holder 19. More specifically, the holder 19 is provided with an opening 19a through which reflected light from a subject that has passed through the lens is incident on the image sensor. The inner diameter of the opening 19a is smaller than the inner diameter of the sleeve 13. It has become. Hereinafter, the opening 19a will be described in detail with reference to FIGS.

[Aperture]
FIG. 3 is a perspective view when the holder 19 is taken out from the lens driving device 1. FIG. 4 is a cross-sectional perspective view showing a state in which the lens 13 is cut in the optical axis direction while paying attention to the sleeve 13 and the holder 19 in the lens driving device 1. FIG. 5 is a cross-sectional side view of the sleeve 13 and the holder 19 shown in FIG. 4 as viewed from the side.

  As shown in FIG. 3, the holder 19 has a shape in which an opening 19a is provided at the center of a plate-like holder bottom surface 19b. And the convex part 19c which protrudes in the sleeve 13 side is formed in the periphery of this opening part 19a. As a result, it is possible to prevent the wear powder adhering to the opening 19a from dropping into the opening 19a due to a change in the airflow (due to the displacement of the sleeve 13) or the like.

  Further, the holder 19 is formed with an abutting portion 19d with which the sleeve 13 (the contact portion 135A) abuts when the moving body is positioned on the image sensor side (image side). The contact portion 19d is formed on the outer periphery of the holder 19 on both sides of the opening portion 19a. Further, the height of the contact portion 19d is formed at a position higher than the lower surface 19b and the convex portion 19c of the holder 19. Therefore, the rear end surface of the sleeve 13 does not come into contact with the holder bottom surface 19b.

  The sleeve 13 includes a first end 133, a second end 134, and a third end 135 that guide the coil 18 in a predetermined position or winding direction.

  The first end portion 133, the second end portion 134, and the third end portion 135 all have a function of regulating the range of the first coil 181 and the second coil 182 in the optical axis direction. Yes. As shown in FIG. 2, an end portion 135 is formed on the image sensor side (image side) (see FIG. 2), and contact portions 135 </ b> A projecting from the third end portion 135 toward the outer periphery are on both sides of the sleeve 13. Is provided.

Further, as shown in FIG. 4, a fitting portion 13 a that can be fitted by rotating the lens barrel is formed on the inner peripheral surface of the sleeve 13. When the lens barrel is fitted, sliding powder or wear powder may be generated due to friction between the outer periphery of the lens barrel and the fitting portion. However, according to the lens driving device 1 according to the present embodiment, the inner diameter of the opening 19a is smaller than the inner diameter of the inner peripheral surface of the sleeve 13 (that is, the inner diameter of the sleeve 13 is the inner periphery of the opening 19a). The generated sliding powder or wear powder adheres to the holder bottom surface 19 b of the holder 19 because it is larger than the inner diameter of the surface. Specifically, as shown in FIG. 5, the inner diameter of the opening 19a and L _1, it has an inner diameter of the inner peripheral surface of the sleeve 13 when the L _2, as L ₁ <L ₂ is satisfied .

  Further, as shown in FIGS. 4 and 5, in the sleeve 13, the inner peripheral surface 13 b has a tapered shape extending in the radial direction in the vicinity of the end portion on the holder 19 side. As a result, the sliding powder or wear powder generated in the fitting portion 13a moves to the rear side along the inner peripheral surface of the sleeve 13 and adheres to the holder 19 at a position further away from the opening 19c. Will do. Therefore, it is possible to reduce the amount of sliding powder or wear powder that falls over the convex portion 19c and falls into the opening portion 19a due to the change in the air flow caused by the displacement of the sleeve 13 (movement in the optical axis direction). Defects can be prevented and image quality deterioration can be prevented.

  Further, as shown in FIG. 5, when the sleeve 13 is located on the image sensor side (image side), the contact portion 135 </ b> A of the sleeve 13 comes into contact with the contact portion 19 d of the holder 19.

[basic action]
In the lens driving device 1 according to the present embodiment, the moving body is normally positioned (held) on the image sensor side (image side) (when the coils of the first coil 181 and the second coil 182 are not energized). . That is, as shown in FIG. 5, the contact portion 135A formed on the sleeve 13 contacts the contact portion 19d formed on the holder 19, but the rear end surface of the sleeve 13 does not contact the holder bottom surface 19b. It is like that. At this time, the wire spring 16 regulates the displacement of the moving body by a magnetic attractive force acting between the wire 17 and the magnet 17. However, since the distance between the wire spring 16 and the magnet 17 is maintained to some extent, the magnetic attractive force between the wire spring 16 and the magnet 17 does not become too strong. As a result, it is possible to prevent the center axis of the moving body from being shifted, and thus to prevent the tilt characteristics from deteriorating.

  In such a state, when a current is passed through the first coil 181 and the second coil 182, the first coil 181 and the second coil 182 receive an upward (front) electromagnetic force, respectively. As a result, the first coil 181, the second coil 182, and the sleeve 13 begin to move toward the subject side (front side).

  At this time, an elastic force that restricts the movement of the sleeve 13 is generated between the first leaf spring 14 and the front end of the sleeve 13 and between the second leaf spring 15 and the rear end of the sleeve 13. . For this reason, when the electromagnetic force that moves the sleeve 13 forward and the elastic force that restricts the movement of the sleeve 13 are balanced, the sleeve 13 stops. In addition, when a reverse current is passed through the first coil 181 and the second coil 182, the first coil 181 and the second coil 182 receive a downward (rear) electromagnetic force, respectively. .

  At that time, by adjusting the amount of current flowing through the first coil 181 and the second coil 182 and the elastic force acting on the sleeve 13 by the first leaf spring 14 and the second leaf spring 15, the sleeve 13 (moving) Body) can be stopped at a desired position. In addition, by stopping the sleeve 13 using the balance between the electromagnetic force and the elastic force, unlike the case where the members are brought into contact with each other so as to be locked with the locking portion or the like, it is possible to prevent occurrence of a collision sound. .

[Main effects of the embodiment]
According to the lens driving device 1 according to the present embodiment, as described with reference to FIGS. 3 to 5, the inner diameter L ₁ of the opening 19 a formed in the holder 19 and the inner diameter L of the inner peripheral surface of the sleeve 13. _{When 2} is compared, the relationship of L ₁ <L ₂ is established. Therefore, sliding powder or wear powder generated at the fitting portion 13a of the sleeve 13 can be prevented from dropping and adhering directly to the glass filter or image sensor on the rear side of the holder 19. And since the convex part 19c which protrudes in the sleeve 13 side is provided in the periphery of the opening part 19a, it prevents that the sliding powder or abrasion powder which fell or adhered to the holder bottom face 19b falls to the opening part 19a. be able to. In this way, if sliding powder or wear powder can be prevented from falling off, image defects can be prevented and image quality deterioration can be prevented.

  Further, in the present embodiment, as shown in FIG. 5, the contact portion 135A formed on the sleeve 13 is in contact with the contact portion 19d formed on the holder 19, but the rear end surface of the sleeve 13 is the holder. It does not contact the bottom surface 19b. For this reason, even when the sleeve 13 moves to the image sensor side or stops, the sliding powder or wear powder attached to the holder bottom surface 19b does not adhere to the rear end face of the sleeve 13.

In the present embodiment, the opening 19a has a round shape, but the present invention is not limited to this. For example, the opening 19a may have a quadrangular shape, a triangular shape, or the inner peripheral surface of the sleeve 13. It is sufficient if it is smaller than the diameter of the lens barrel (ie, the outer peripheral surface of the lens barrel). Conventionally, since the lens barrel is sometimes inserted from the rear side of the sleeve 13, the relationship of L ₁ > L ₂ is generally established. However, in this embodiment, instead of abandoning the response to such a case, it is possible to prevent image defects and contribute to the prevention of image quality deterioration.

  In addition to the camera-equipped mobile phone, the lens driving device 1 can be attached to various electronic devices. For example, PHS, PDA, bar code reader, thin digital camera, surveillance camera, vehicle rear view confirmation camera, door with optical authentication function, and the like.

  The lens driving device according to the present invention is useful for preventing image defects due to sliding powder or wear powder and preventing image quality deterioration.

It is a perspective view which shows the external appearance structure of the lens drive device which concerns on embodiment of this invention. It is a disassembled perspective view which shows the machine structure of the lens drive device which concerns on embodiment of this invention. It is a perspective view when a holder is taken out from the lens driving device. It is a cross-sectional perspective view which shows a mode when paying attention to a sleeve and a holder in a lens drive device, and cut | disconnecting in an optical axis direction. It is a cross-sectional side view when the sleeve and holder shown in FIG. 4 are seen from the side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens drive device 11 Yoke 12 Cover 13 Moving body (sleeve)
14 1st leaf spring 15 2nd leaf spring 16 Wire spring 17 Magnet 18 Coil 19 Holder 19a Opening 19b Holder bottom 19c Projection

Claims (1)

A cylindrical moving body that holds the lens and is movable in the optical axis direction;
A support for supporting the moving body;
In a lens driving device having a magnetic driving mechanism for driving the moving body in the optical axis direction,
The support is formed with an opening through which reflected light from a subject that has passed through the lens is incident on the image sensor.
The moving body has a lens barrel in which a lens is incorporated, and a sleeve for holding the lens barrel.
The inner diameter of the sleeve is larger than the inner diameter of the opening, and in the vicinity of the end of the support on the opening side, the inner peripheral surface of the sleeve has a tapered shape spreading in the radial direction,
On the periphery of the opening, a convex portion that protrudes toward the movable body is formed ,
The lens driving device, wherein the lens barrel is inserted from the subject side of the sleeve .

Images