JP2017156607A - Lens unit and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact and inexpensive lens unit in which the optical axis direction of a lens can be displaced precisely, and an imaging device including such a lens unit.SOLUTION: A cam unit 106 is energized to a reception unit 131 using a compression spring 109 in an arrow direction (Z direction) in Fig. 2; therefore, the friction force that operates between a lower surface of the cam unit 106 and an upper surface of a base unit 105a is increased. Thus, even if rattling occurs between gears of, for example, a worm gear 107a and a worm wheel 106a, the holding force of the cam unit 106 to the base unit 105a is increased, so that the overshooting or the like can be effectively suppressed.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a lens unit and an imaging device that enable displacement of a lens in the optical axis direction.

  In recent years, imaging devices such as digital still cameras and portable terminals equipped with an imaging device using a solid-state imaging device such as a CCD (Charge Coupled Device) type image sensor or a CMOS (Complementary Metal Oxide Semiconductor) type image sensor have become widespread. Yes. However, it is generally said that the user's needs are to promote further improvement in image quality as well as to improve the portability and design of these imaging devices. As an example of promoting high image quality, there is a case where an imaging device is provided with a focusing function for displacing a focusing lens in the optical axis direction in order to suppress blurring of a subject. On the other hand, in order to improve the portability and design of the imaging device, it is necessary to reduce the size of the imaging device.

  Here, as shown in Patent Document 1, in order to displace the zoom lens in the optical axis direction, a part of the lens moving frame body that holds the zoom lens (the contact portion) is disposed on the cam portion provided on the outer periphery of the rotating body. In which the zoom lens is driven integrally with the lens holding frame body via the contact portion. Since the rotation angle of the rotating body accurately corresponds to the position in the optical axis direction of the cam portion with which the contact portion of the lens moving frame contacts, the zoom lens can be accurately displaced by determining the rotation angle.

JP 2006-98652 A

  By the way, the rotation body of patent document 1 is transmitted the rotational driving force of a motor via a gear train. In general, in order to smoothly transmit the rotational driving force, backlash is often provided between the meshing teeth of the gear train. However, if there is play between the meshing teeth, even if the gear on the drive source side is stationary, the gear of the rotating body on the driven side will be allowed to rotate arbitrarily by the backlash. There arises a problem that the lens holding frame cannot be accurately positioned. As a more specific example, due to the inertial force of each part during driving, the amount of rotation corresponding to the gear reduction ratio of the rotating body meshing with the amount of rotation of the gear on the drive source side is not stable. There is a risk that a so-called overshoot phenomenon that becomes excessive within a minute may occur.

  On the other hand, a configuration in which a spring member or the like for urging the contact portion of the lens moving frame body in one direction in the optical axis direction toward the cam portion is also conceivable. According to such a configuration, the tangential component force corresponding to the inclination is generated at the contact point of the cam portion by the biasing force of the spring member or the like, and this is used to apply torque in one direction of rotation to the rotating body. Since it can always be applied, the overshoot phenomenon or the like can be suppressed by suppressing the separation between the meshing teeth. Here, if the tangential component force is increased so that the separation between the meshing teeth can be effectively suppressed, the cam member is inclined with respect to the direction perpendicular to the axis, or the spring member is strengthened to increase the force. It is necessary to be able to give power.

  However, when the inclination of the cam portion is increased, the entire length of the rotating body is increased, leading to an increase in size of the configuration. On the other hand, when the spring member or the like is reinforced, there is a risk that an indentation or a flaw of the abutting portion may occur in the cam portion, preventing smooth sliding of the abutting portion with respect to the cam portion. There is a problem that a high-output drive source with an increased rotational driving force corresponding to the member or the like is required. Therefore, there is a demand for a method that can effectively suppress the separation between the meshing teeth without depending on the tangential component force acting on the contact point of the cam portion.

  The present invention aims to solve the above-described problems, and provides a lens unit that can realize a highly accurate displacement in the optical axis direction of a lens while being small and inexpensive, and an imaging apparatus using the lens unit. With the goal.

The lens unit of the present invention is
A base with a drive source installed;
A first gear that rotates according to the driving force of the driving source;
A second gear provided with a cam surface, rotatably contacted with the base, and capable of transmitting the driving force by meshing with the first gear;
A contact portion that contacts the cam surface, and a lens holding frame that holds the lens,
As the second gear to which the driving force is transmitted rotates with respect to the base, the optical axis position between the cam surface and the contact portion is displaced, whereby the lens holding frame is moved. It is designed to be positioned in the optical axis direction,
An elastic member for biasing the second gear with respect to the base is provided.

The lens unit of the present invention is
A base with a drive source installed;
A first gear that rotates according to the driving force of the driving source;
A second gear provided with a cam surface, rotatably contacted with the base, and capable of transmitting the driving force by meshing with the first gear;
A contact portion that contacts the cam surface, and a lens holding frame that holds the lens,
As the second gear to which the driving force is transmitted rotates with respect to the base, the optical axis position between the cam surface and the contact portion is displaced, whereby the lens holding frame is moved. It is designed to be positioned in the optical axis direction,
At least one of the contact surfaces of the base portion and the second gear that contact each other is a rough surface.

  According to the present invention, it is possible to provide a lens unit that can realize a highly accurate displacement of the lens in the optical axis direction while being small and inexpensive, and an imaging apparatus using the lens unit.

It is an exploded view of the imaging device 100 including the lens unit concerning this Embodiment. It is the figure which cut | disconnected the imaging device 100 which removed the imaging unit in the surface which passes along the II-II line | wire of FIG. Although it is a perspective view of the cam unit 106 concerning this Embodiment, the worm wheel is simplified. It is a perspective view of the base part 105a concerning this Embodiment, and the axial part 105b. It is a perspective view of the cam unit 106 'according to another embodiment, but the worm wheel is simplified. It is a perspective view of base part 105a 'concerning another embodiment, and axial part 105b. It is a perspective view of cam unit 106 'concerning a modification. It is a perspective view which removes and shows the upper cover and imaging unit of an imaging device containing the lens unit concerning another embodiment. It is the figure which cut | disconnected the imaging device which removed the imaging unit in the surface which passes along the IX-IX line | wire of FIG. 8, and looked at the arrow direction.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an exploded view of an imaging apparatus 100 including a lens unit according to the present embodiment, in which a part of the casing (part indicated by hatching) is cut away. FIG. 2 is a view of the imaging apparatus 100 with the imaging unit removed, cut along a plane passing through line II-II in FIG. 2 and viewed in the direction of the arrow, but the imaging unit is removed. FIG. 3 is a perspective view of the cam unit 106 according to the present embodiment, but the worm wheel is simplified. FIG. 4 is a perspective view of the base portion 105a and the shaft portion 105b according to the present embodiment. The imaging device 100 is mounted on a mobile device such as a mobile phone or a smartphone, and functions as a camera. Here, the optical axis direction of the lens is the Z direction, and the directions orthogonal to the Z direction are the X direction and the Y direction.

  In FIG. 1, an imaging unit 110 is attached to the lower side of a box-shaped casing 101 without an upper wall. The imaging unit 110 includes a rectangular substrate 111 and a photoelectric conversion unit 112 made of a CCD sensor or a CMOS sensor formed on the upper surface of the substrate 111. The imaging unit 110 is connected to a control circuit (not shown), and has a function of converting an optical image into an electrical signal and outputting it to the outside.

  The housing 101 has a bottom wall 101a to which the imaging unit 110 is attached, and side walls 101b to 101e extending upward from the periphery of the bottom wall 101a (however, the side wall 101e is shown in a cutout state). An opening (not shown) is formed on the bottom wall 101a so as to face the photoelectric conversion portion 112, and two guide shafts 102 and 103 are implanted as guide members with the opening interposed therebetween. Cylindrical guide shafts 102 and 103 extend in parallel to an optical axis direction (Z direction) of a lens LS to be described later. The upper ends of the guide shafts 102 and 103 are held in contact with the lower surface of the upper lid 130 as shown in FIG.

  An L-shaped hook 104 is formed near the guide shaft 102 in the bottom wall 101a. Further, an L-shaped hanging portion 108 is formed on the inner surface of the side wall 101d in the vicinity of the guide shaft 103 as shown in FIG.

  Further, a cylindrical base portion 105a as shown in FIG. 4 is formed in the vicinity of the guide shaft 102 in the bottom wall 101a. From the center of the smooth upper surface 105c of the base portion 105a, the shaft portion 105b is connected to the optical axis OA. It extends parallel to. As shown in FIG. 2, the upper end of the shaft portion 105 b is held in contact with a receiving portion 131 formed on the lower surface of the upper lid 130.

  As shown in FIG. 3, the cam unit 106 as the second gear has a cam piece 106b bonded or integrally formed on the upper surface of the worm wheel 106a. The upper surface of the cam piece 106b is formed with a spiral cam surface 106c whose height changes in the circumferential direction. The center of the cam surface 106c is an engaging portion 106d that rises in a cylindrical shape.

  A through hole 106e is formed at the center of the cam unit 106, and a shaft portion 105b is rotatably fitted to the through hole 106e. In this state, the smooth lower surface 105g of the cam unit 106 and the upper surface 105c of the base portion 105a are in contact with each other as contact surfaces. Further, in FIG. 2, a compression spring 109 is disposed between the lower surface of the receiving portion 131 and the engaging portion 106 d and around the shaft portion 105 b, and the cam unit 106 is connected to the receiving portion 131. In FIG. 2, it is biased in the arrow direction (downward in the Z direction). As an elastic member, rubber or resin may be provided instead of the compression spring 109. The engaging portion 106d may have a flat upper end or a tapered surface on which the compression spring 109 can be fitted.

  Further, a motor 107 as a drive source is attached to the bottom wall 101a. A worm gear 107 a as a first gear is attached to the rotating shaft of the motor 107, and the worm gear 107 a meshes with the worm wheel 106 a of the cam unit 106. The axis of the worm gear 107a extends in the X direction.

  In FIG. 1, a holding frame (lens holding frame) 120 that holds a lens LS (a plurality of lenses) that is a focusing lens is generally cylindrical and has two protruding portions 121 that protrude in a direction perpendicular to the optical axis. , 122. The protrusion 121 has a circular opening 121 a that engages with the guide shaft 102, and the protrusion 122 has an opening 122 a that engages with the guide shaft 103. Here, by making the opening 122a a long hole extending in the direction perpendicular to the optical axis, the degree of difficulty in assembly can be reduced. In such a case, it is preferable to perform the assembly reference by fitting the guide shaft 102 and the circular opening 121a.

  Further, a plate-like arm portion 123, which is a contact portion, extends from the protruding portion 121 toward the cam unit 106, and the tip thereof is in contact with the cam surface 106c as shown in FIG. Furthermore, the protrusion part 121 is provided so that the collar part 124 may protrude. Ends of coil springs 125 as first urging members are respectively attached to the flange portion 124 and the hooking portion 104 of the housing 101, and as shown in FIG. The holding frame 120 is urged in the Z direction. Further, the cam unit 106 is also biased toward the bottom wall 101a via the arm portion 123, whereby the position of the cam unit 106 in the optical axis direction is also fixed. Note that the biasing force of the coil spring 125 that presses the arm portion 123 and the cam surface 106c is set to a relatively low value such that the cam surface 106c does not have a sliding mark or the like.

  On the other hand, the flange portion 126 is provided on the protruding portion 122 so as to protrude. Ends of coil springs 127 as second urging members are respectively attached to the collar portion 126 and the hooking portion 108 of the housing 101, and the holding frame 120 in the Y direction toward the side wall 101e side of the housing 101. Is energized. The coil spring 127 has a function of removing the backlash by urging the holding frame 120 in the Y direction with respect to the guide shafts 102 and 103 and positioning the optical axis OA with respect to the housing 101 with high accuracy.

  A rectangular plate-shaped upper lid 130 is attached to the upper ends of the side walls 101 b to 101 e of the housing 101. An opening 130 a is formed in the upper lid 130. The casing 101 including the base portion 105a and the upper lid 130 constitute a base portion. With the lens LS and the holding frame 120 assembled between the housing 101 and the upper lid 130, the opening 130a of the upper lid 130 exposes the object side. In this state, the holding frame 120 can be displaced in the optical axis direction while being guided by the guide shafts 102 and 103. The coil spring 125, the casing 101, the upper lid 130, the lens LS, the holding frame 120, the cam unit 106, and the worm gear 107a of the motor 107 constitute a lens unit.

  Next, the operation of the imaging apparatus according to this embodiment will be described. At the time of shooting, when the lens LS of the imaging apparatus 100 mounted on an imaging device (not shown) is directed toward the subject, the subject light incident through the lens LS forms an image on the photoelectric conversion unit 112 of the imaging unit 110. The photoelectric conversion unit 112 changes the image of the subject into an electrical signal and outputs it to a liquid crystal display (not shown). Thereby, the image of the subject is displayed on the display. When the user performs a release operation at an appropriate timing, the subject is imaged, the image data is output from the photoelectric conversion unit 112, and after predetermined image processing, is recorded in a memory (not shown).

  The imaging apparatus 100 according to the present embodiment can perform a focusing operation by displacing the lens unit in the optical axis direction according to the subject distance. After measuring the distance to the subject (subject distance) with a distance measuring device (not shown), when the motor 107 is driven to rotate forward to rotate the worm gear 107a, the worm wheel 106a rotates in the forward direction, and the cam unit 106 Rotate in the same direction. Here, since the distal end of the arm portion 123 is pressed against the cam surface 106c of the cam piece 106b by the urging force of the coil spring 125, the height position of the cam surface 106c in the Z direction depends on the rotation of the cam unit 106. In response to the change, the holding frame 120 together with the arm portion 123 is displaced in the optical axis direction while being guided by the guide shafts 102 and 103, and the lens LS can be displaced to a position in the optical axis direction suitable for the subject distance. .

  In the present embodiment, as described above, since the biasing force of the coil spring 125 is relatively small and the inclination of the cam surface 106c is also small, when a pressing force is applied to the cam surface 106c from the tip of the arm portion 123, The tangential component force generated on the cam surface 106c is reduced. Therefore, it is difficult to suppress overshoot caused by the inertial force of each part during driving due to the presence of play between the teeth of the worm gear 107a and the worm wheel 106a.

  In this embodiment, therefore, the compression spring 109 is used to bias the cam unit 106 in the arrow direction (downward in the Z direction) in FIG. The frictional force acting between the upper surface 105c of the base portion 105a is increased. Thereby, even if there is play between the teeth of the worm gear 107a and the worm wheel 106a, the holding force of the cam unit 106 with respect to the base portion 105a is increased, so that overshoot or the like can be effectively suppressed.

  FIG. 5 is a perspective view of a cam unit 106 'according to another embodiment, but the worm wheel is simplified. FIG. 6 is a perspective view of a base portion 105a 'and a shaft portion 105b according to another embodiment. The cam unit 106 'shown in FIG. 5 has a flat surface portion 106f protruding in an annular shape on the lower surface 106g (surface facing the base portion 105a'), and the surface thereof is rough. On the other hand, the annular surface 105c 'around the shaft portion 105b in the base portion 105a' is a rough surface. Other configurations are the same as those of the above-described embodiment.

  The surface of the flat portion 106f and the annular surface 105c 'can be formed simultaneously with molding, for example, by providing a texture on the transfer surface of an injection mold. The surface roughness of the flat portion 106f and the annular surface 105c 'is preferably 12.5 μm or more and 200 μm or less in terms of arithmetic average roughness Ra. The friction coefficient between the surface of the flat portion 106f and the annular surface 105c 'is preferably 0.5 or more. It is sufficient that at least one of the surface of the flat portion 106f and the annular surface 105c 'is a rough surface.

  According to the present embodiment, the surface of the flat portion 106f and the annular surface 105c ′ that are in contact with each other have a predetermined rough surface, so even if the compression spring 109 is not used, the worm gear 107a and the worm wheel 106a Even if there is play between the teeth, the frictional force against the base portion 105a of the cam unit 106 can be increased, and overshoot and the like can be effectively suppressed. Note that, by using the compression spring 109 in combination, it is possible to further increase the holding force of the cam unit 106 with respect to the base portion 105a.

  FIG. 7 is a perspective view of a cam unit 106 ′ according to a modification. In the present modification, three fan shapes are formed in which the flat portion 106f is spaced apart at equal intervals in the circumferential direction with respect to the embodiment of FIG. As a result, the area of the flat surface portion 106f can be reduced, so that the die machining accuracy and the like can be increased while reducing the cost, and the friction coefficient at the time of contact with the annular surface 105c ′ can be more stably maintained. become.

  FIG. 8 is a perspective view showing the imaging apparatus including the lens unit according to another embodiment with the upper lid and the imaging unit removed, with a part of the casing (part indicated by hatching) cut away. Yes. FIG. 9 is a view of the image pickup apparatus with the image pickup unit removed, cut along a plane passing through the line IX-IX in FIG. 8 and viewed in the direction of the arrow, with the upper lid attached.

  In the present embodiment, the flange portion 124 provided on the protruding portion 121 of the holding frame 120 and the hanging portion 104 provided on the bottom wall 101a of the housing 101 are displaced with respect to the Z direction, and accordingly As shown in FIG. 9, the axis AX of the coil spring 128 (biasing member) having both ends attached to the flange portion 124 and the hanging portion 104 is inclined with respect to the Z direction and the Y direction. Accordingly, the coil springs 125 and 127 in the embodiment of FIGS. 1 and 2 are not provided. Other configurations are the same as those of the above-described embodiment.

  According to the present embodiment, the tip of the arm portion 123 can be brought into pressure contact with the cam surface 106c in the same manner as the coil spring 125 by the Z-direction component Fz of the biasing force of the coil spring 128 attached to be inclined with respect to the Z direction. . Further, the optical axis OA is accurately positioned with respect to the housing 101 by urging the holding frame 120 in the Y direction with respect to the guide shafts 102 and 103 by the Y direction component Fy of the urging force of the coil spring 128. Can do. In addition, since the coil spring 128 is provided instead of the coil springs 125 and 127, the number of parts is reduced, which contributes to cost reduction.

  In the above embodiment, the driving force of the motor is transmitted to the cam unit via the worm gear and the worm wheel meshed with each other. However, the driving force is not limited to this and is transmitted, for example, via a spur gear. May be.

DESCRIPTION OF SYMBOLS 100 Image pick-up device 101 Case 101a Bottom wall 101b-101e Side wall 102, 103 Guide shaft 104 Hanging part 105a, 105a 'Base part 105b Shaft part 105c Upper surface 105c' Annular surface 106, 106 'Cam unit 106a Warm wheel 106b Cam piece 106c Cam Surface 106d Engaging portion 106e Through-hole 106f Flat portion 107 Motor 107a Worm gear 108 Hanging portion 109 Compression spring 110 Imaging unit 111 Substrate 112 Photoelectric conversion portion 120 Holding frame 121, 122 Protruding portion 121a Circular opening 122a Opening 123 Arm portion 124 Hook portion 125 Coil spring 126 鈎 portion 127 Coil spring 128 Coil spring 130 Upper lid 130a Opening portion 131 Receiving portion

Claims (8)

A base with a drive source installed;
A first gear that rotates according to the driving force of the driving source;
A second gear provided with a cam surface, rotatably contacted with the base, and capable of transmitting the driving force by meshing with the first gear;
A contact portion that contacts the cam surface, and a lens holding frame that holds the lens,
As the second gear to which the driving force is transmitted rotates with respect to the base, the optical axis position between the cam surface and the contact portion is displaced, whereby the lens holding frame is moved. It is designed to be positioned in the optical axis direction,
The lens unit which provided the elastic member which urges | biases the said 2nd gear with respect to the said base.   The lens unit according to claim 1, wherein the second gear is provided with an engaging portion that engages with the elastic member. A base with a drive source installed;
A first gear that rotates according to the driving force of the driving source;
A second gear provided with a cam surface, rotatably contacted with the base, and capable of transmitting the driving force by meshing with the first gear;
A contact portion that contacts the cam surface, and a lens holding frame that holds the lens,
As the second gear to which the driving force is transmitted rotates with respect to the base, the optical axis position between the cam surface and the contact portion is displaced, whereby the lens holding frame is moved. It is designed to be positioned in the optical axis direction,
A lens unit in which at least one of the contact surfaces of the base portion and the second gear that contact each other is a rough surface.   The lens unit according to claim 3, wherein the surface roughness of the rough surface is 12.5 μm or more in terms of arithmetic average roughness Ra.   The lens unit according to claim 3 or 4, wherein a friction coefficient of the rough surface is 0.5 or more.   A guide member that is provided in the base and guides the lens holding frame in the optical axis direction, a first biasing member that biases the lens holding frame in the optical axis direction with respect to the base, and the base The lens unit according to claim 1, further comprising a second urging member that urges the lens holding frame in a direction orthogonal to the optical axis.   2. A guide member that is provided in the base portion and guides the lens holding frame in the optical axis direction, and a biasing member that applies a biasing force to the base portion in a direction inclined from the optical axis of the lens. The lens unit in any one of -5.   An imaging apparatus comprising: a photoelectric conversion unit that photoelectrically converts a subject image; and the lens unit according to claim 1.

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