JP2005128114A - Optical module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical module, having a moving mechanism capable of adjusting a focusing position on a light-receiving element. <P>SOLUTION: The optical module 3 includes first lens holders 13 and 16, a second lens holder 19 positioned at an object side therefrom, a lens barrel 11 circumscribed on the first lens holder and held slidably in the direction of an optical axis, and a cylindrical cam 15 arranged at the outer periphery and modifying the position of the first lens holder. The first lens holders 13 and 16 is provided with projection members 131 and 161 extending from the side. Through holes 11A and 11B which allow movement in the direction of the optical axis LD of the projection member are formed, and a cam face 151 guiding the projection member is formed on the inner wall of the cylindrical cam. A second lens holder is fixed on the upper end of the lens barrel and has a sliding face positioning the cylindrical cam. An elastic member 12, urging the cylindrical cam toward the sliding face of the second lens holder, is arranged. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical module included in a small camera or the like using an image sensor such as a CCD.

  In recent years, electronic devices such as mobile phones and notebook computers equipped with a minute camera have been widely provided. There is a great demand for downsizing and weight reduction of these electronic devices, and it is required to further reduce the size and weight of the camera incorporated therein. Therefore, it is necessary to further reduce the size and weight of the optical module that is an optical system component of the camera.

  On the other hand, in order to obtain a clear image with a miniaturized optical module, dimensional accuracy in the optical axis direction is particularly required. In a miniaturized optical module, an image deteriorates if there is even a slight deviation between the light receiving surface of the image sensor and the focusing position (back focus) of the lens system. Recently, a small optical module that has a plurality of lenses and has a zoom function even if it is small in size has been provided. In the case of such an optical module, if the optical axis on the lens side is slightly inclined with respect to the optical axis of the image pickup device arranged on the substrate side, the captured image is deteriorated so that the optical axis on the lens side is not inclined. Assembling is important.

  For example, Patent Document 1 discloses a lens driving device for a small camera including a plurality of lenses. As shown in FIG. 10, this Patent Document 1 discloses a lens driving device 300 that uses a plate cam 310 to reduce the number of sensors and signal processing devices, thereby reducing the size and simplifying the configuration. The lens position in the optical module is moved during macro photography and zoom photography. In the case of the lens driving device 300 disclosed in Patent Document 1, the lens position is changed by rotating the plate cam 310 around the rotation shaft 311. Specifically, each of the lens frames (lens holders) 305 and 306 is provided with pins 307 and 308 as cam followers. These pins 307 and 308 are engaged with cam grooves 312 and 313 formed in the plate cam 310. By rotating the plate cam 310, the lens holders 305 and 306 can be set at predetermined positions.

JP 2002-189165 A

  When moving the lens as described above, it is necessary to adjust the focus and magnification. In the lens driving device 300 disclosed in FIG. 10, the shapes (cam curves) of the cam grooves 312 and 313 are defined in consideration of this point. With this cam curve, the lens and the CCD are adjusted to have an optimum distance. The optical module is manufactured with a predetermined dimensional accuracy. However, in the actual manufacturing process, the relative position in the optical axis direction of the image sensor arranged on the substrate may change slightly, or the lens position and orientation may change slightly.

  As described above, when the relative position between the imaging element and the lens deviates from the planned position, it is necessary to adjust the position so that the back focus matches. However, when a plate cam is used as in the device shown in Patent Document 1, it is necessary to take measures such as changing the cam curve of the cam grooves 312 and 313 or changing the position of the rotating shaft 311. Considering the actual manufacturing process, it is not realistic to change the rotation axis. Therefore, a plurality of plate cams 310 having different cam curves are prepared, and the work of focusing is performed by appropriately changing the plate cams. However, such work is complicated.

  Further, as shown in FIG. 10, in the lens driving device 300 disclosed in Patent Document 1, a plate cam 310 is disposed on one side of the lens holders 305 and 306, and these lens holders are rotated by rotating the plate cam 310. Is moved in the optical axis direction. However, in such a structure, a load is applied only to the lens holder side via the pins 307 and 308, so that the optical axis of the lens holder is shaken. As a result, since the optical axis on the lens side is inclined as described above, there is a problem that the captured image is deteriorated.

  An object of the present invention is to solve the above-described problems and provide an optical module that can accurately set a back focus without causing a positional shift of the lens holder in the optical axis direction. It is another object of the present invention to provide an optical module that has a structure for reliably moving the lens holder along the optical axis direction and can reliably suppress the inclination of the optical axis.

  The object is to circumscribe the first lens holder, the second lens holder located closer to the object side than the first lens holder, and the first lens holder, and the first lens holder is positioned in the optical axis direction. An optical module comprising: a lens barrel that is slidably held on the lens barrel; and a cylindrical cam that is disposed on an outer periphery of the lens barrel and changes a position of the first lens holder, wherein the side surface of the first lens holder A projecting member extending from the through hole, and a through hole is formed in the lens barrel to allow the projecting member to move in the optical axis direction, and the projecting member is guided to a predetermined position on the inner wall of the cylindrical cam. A cam surface is formed, the second lens holder is fixed to an upper end portion of the lens barrel, and has a sliding surface for positioning the cylindrical cam in an optical axis direction. A bullet urging toward the sliding surface of the lens holder Can be achieved by an optical module member is disposed.

  According to the present invention, the cylindrical cam that moves the first lens holder is brought into contact with the second lens holder by the elastic member. Since the second lens holder is fixed to the upper part of the lens barrel, the cylindrical cam can be positioned at a desired position in the optical axis direction. Therefore, since the lens included in the optical system can be arranged at a desired position, the back focus can be set with high accuracy.

  The second lens holder is preferably screwed so as to be movable in the optical axis direction with respect to the upper end portion of the barrel. With such a structure, the back focus can be easily corrected by moving the second lens holder in the optical axis direction even when a position error in the optical axis direction occurs due to parts or assembly.

  The elastic member may be a ring-shaped conical coil spring or a bamboo child spring disposed under the cylindrical cam. By adopting such a spring, the installation space can be reduced, and the optical module can be downsized.

  The first lens holder preferably includes a plurality of the protruding members. When the first lens holder moves along the cam groove of the cylindrical cam, it is possible to prevent the optical axis on the lens side from being inclined with respect to the optical axis on the substrate side when the plurality of protruding members are provided in this way. . In addition, since the lens holder is held by a plurality of projecting members, the structure is excellent in impact resistance. A plurality of the first lens holders can be provided in the lens barrel.

  It is desirable that the protruding members are arranged on the side surfaces of the first lens holder so that the directions thereof are different from each other. For example, it is possible to adopt a structure in which one lens holder is provided with two projecting members in opposite directions on a straight line, and the projecting parts are arranged so that the straight lines intersect between different lens holders. With such a structure, it is possible to more reliably prevent a situation where the optical axis on the lens side is inclined. A portable electronic device including the optical module as described above can obtain a small and clear image.

  ADVANTAGE OF THE INVENTION According to this invention, in the optical module which has a moving mechanism of a lens, the optical module which can easily adjust the focus of a lens to the light-receiving surface of a light receiving element can be provided.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view showing the inside of the optical module according to the embodiment so as to be confirmed. In FIG. 1, a filter or a diaphragm interposed in the middle is omitted to facilitate understanding of the characteristic configuration. A CCD 2 serving as an image sensor is fixed on a substrate 1 on which a predetermined wiring pattern is formed. As the substrate 1, for example, a flexible wiring substrate (FPC substrate) can be employed. The optical system unit 3 is arranged so that a photographed image is formed on the CCD 2 arranged on the substrate 1. The optical module referred to in this specification may be the lens and the optical system unit 3 that drives the lens in the optical axis direction LD of the CCD, or drives the CCD 2, the substrate 1, and a lens holder described later. It may be understood that the structure also includes an actuator to be operated. Hereinafter, a structure included in the optical system unit, a cylindrical cam preferable for use in the present optical system unit, and a positioning structure preferable for manufacturing an optical module will be described in order.

(Structure of optical system unit)
The optical system unit 3 includes a lens barrel 11, a ring-shaped conical coil spring 12 as an elastic member, a third lens holder 13, a third lens 14, a cylindrical cam 15, a second lens holder 16, and a second lens from the substrate 1 side. 17, a first lens 18 and a first lens holder 19 are included.

  The lens barrel 11 includes a bottom plate 110 on the bottom side. The lens barrel 11 has a substantially cylindrical shape and is disposed so as to surround the CCD 2 fixed to the substrate 1. An opening (not shown) having a shape corresponding to the shape of the CCD 2 is formed in the bottom plate 110. When the lens barrel 11 is set on the substrate 1, the CCD 2 is fitted in the opening of the bottom plate 110. The bottom plate 110 is formed in a disk shape larger than the main body cylindrical portion of the lens barrel 11, and an outer peripheral portion thereof protrudes outward to form a flange portion 115. As will be described later, the coil spring 12 is placed on the flange portion 115.

  A plurality of guide grooves 11 </ b> A to 11 </ b> H are formed on the side wall of the lens barrel 11. Among these guide grooves, the four guide grooves 11A, 11B, 11E, and 11F are formed as long grooves extending in the optical axis direction LD by partially cutting the side wall of the lens barrel 11. Other guide grooves are formed on the inner surface of the side wall. Although these guide grooves 11A to 11F will be described in detail later, the four guide grooves 11A, 11C, 11E, and 11G are formed to guide the third lens holder 13, and the other four guide grooves 11B, 11D, and 11F are formed. 11H are formed to guide the second lens holder 16.

  The coil spring 12 is formed in a ring shape so as to have a conical shape with a winding radius enlarged toward the lower part. The coil spring 12 is fitted on the outer periphery of the main body cylindrical portion of the lens barrel 11 and is placed on the flange portion 115 as described above. As pointed out above as a problem, if the relative positional relationship between the CCD 2 and the lens arranged on the substrate 1 is shifted in the manufacturing process, the focus position (back focus) of the lens is shifted from the light receiving surface of the CCD 2 and thus clear. Correct images cannot be obtained. Therefore, in this optical module, the cylindrical cam 15 for guiding the lens is urged to the first lens holder 19 so that the focal position matches the light receiving surface of the CCD 2 by adjusting the lens position, and the position of the first lens holder. The structure which can adjust is adopted. Specifically, the bottom portion of the cylindrical cam 15 is supported by the coil spring 12 and biased toward the first lens holder 19 positioned above. With such a structure, the lens position of the cylindrical cam 15 in the optical axis direction LD is stabilized.

  The structure in which the upper surface of the cylindrical cam 15 is brought into contact with the lower surface of the first lens holder 19 to stabilize the lens position as described above will be described in more detail. The upper surface of the cylindrical cam 15 is formed flat as shown in FIG. The lower surface of the first lens holder 19 with which the upper surface of the cylindrical cam 15 abuts is also formed flat. Since the cylindrical cam 15 rotates as will be described later, the lower surface of the first lens holder 19 with which the upper surface of the cylindrical cam 15 abuts becomes a sliding surface. On the other hand, the first lens holder 19 is fixed to the upper part of the lens barrel 11 when the present optical module is assembled. More specifically, a female screw portion (not shown) that engages with a male screw portion 117 formed on the upper outer periphery of the lens barrel 11 is formed on the inner wall of the first lens holder 19.

  The lens barrel 11 is installed on the substrate 1. A first lens holder 19 is fixed to the top of the lens barrel 11. Therefore, the position of the first lens holder 19 in the optical axis direction LD can be kept constant from the substrate 1. By pressing the cylindrical cam 15 against the first lens holder 19 using the coil spring 12, the position of the cylindrical cam 15 in the optical axis direction LD can be stabilized. As will be described later, lens holders 13 and 16 for holding lenses 14 and 17 are engaged with the cylindrical cam 15 to control the movement thereof. Therefore, by keeping the position of the cylindrical cam 15 stable, the positions of the plurality of lenses 14 and 17 in the optical axis direction are held at their intended positions via the cylindrical cam 15.

  In particular, in the present embodiment, since the first lens holder 19 is screwed onto the upper portion of the lens barrel 11 with a screw, the height position of the cylindrical cam 15 can be easily changed by rotating the first lens holder 19. . Therefore, even if the back focus is shifted due to an error in assembling the CCD 2 to the substrate, the back focus can be easily corrected by rotating the first lens holder 19. In the present optical system unit 3, by rotating the first lens holder 19 above the lens barrel 11, errors in parts and assembly can be easily eliminated.

  As described above, the present optical module positions the first lens holder 19 serving as a reference with high accuracy by simply arranging the coil spring 12 under the cylindrical cam 15. As a result, it is possible to realize a lens moving mechanism that ensures focusing on the CCD 2 arranged on the substrate without changing the cam curve or the like as in the prior art.

  Further, since the coil spring 12 is formed in a conical shape, it is in wide contact with the bottom of the cylindrical cam 15 and urges upward. Since the coil spring 12 has a conical shape, it has an arrangement configuration in which no coil is present immediately below the coil, so that the contact height during compression can be reduced. That is, the coil spring 12 has a shape that can be arranged in a narrow space. Then, when a load is applied to the coil spring 12, the swelled portion sinks downward and is deformed so as to be flattened. Therefore, the coil spring 12 can be deformed even lower during operation. Therefore, the coil spring 12 has a feature that it can withstand a relatively large load with a small volume. In the present embodiment, the conical coil spring 12 is employed, but a so-called bamboo child spring in which a leaf spring is spirally wound can be similarly employed.

  The cylindrical cam 15 is disposed so as to surround the outer periphery of the lens barrel 11. A plurality of cam grooves (cam surfaces) 151 are formed on the inner wall of the cylindrical cam 15. The third lens holder 13 and the second lens holder 16 are provided with engaging pins as projecting members that engage with the cam grooves 151. Specifically, the third lens holder 13 includes two engagement pins 131-1 and 131-2 protruding in the radial direction, and similarly, the second lens holder 16 is an engagement pin 161-1 protruding in the radial direction. , 161-2. Using these engagement pins as cam followers, the shape of the cam groove 151 is defined so as to move along a predetermined locus. The relationship between the cam groove 151 of the cylindrical cam 15, the engagement pins 131-1 and 131-2, and the engagement pins 161-1 and 161-2 will be described in detail later.

  A rack portion 159 indicated by reference numeral 159 is formed on the outer periphery of the cylindrical cam 15. The rack portion 159 meshes with a driving gear not shown in FIG. As a result, the cylindrical cam 15 rotates about the optical axis direction LD. Based on this operation, the third lens holder 13 and the second lens holder 16 are moved along the optical axis direction LD.

  Next, the lens included in the optical system unit 3 and the lens holder that holds them will be described. The third lens 14 is a correction system lens disposed at a position closest to the substrate 1, and is held by the third lens holder 13. The second lens 17 is a variable power lens disposed in the middle, and is held by the second lens holder 16. The first lens 18 is an objective lens located on the subject side, and is held by a first lens holder 19. The third lens holder 13 and the second lens 17 are moved to desired positions on the optical axis direction LD by cam grooves 151 formed on the inner wall of the cylindrical cam 15 while being accommodated in the lens barrel 11. As a result, the distance between the third lens 14 and the substrate 1 and the distance between the lenses 14, 17, and 18 are changed. Therefore, it is possible to perform imaging while changing the focal length from wide (WIDE) to tele (TELE). It becomes possible.

  FIG. 2 is an enlarged view of the third lens holder 13 and the second lens holder 16 shown in FIG. The two lens holders are set in the lens barrel 11 so as to approach each other from above and below as shown in the figure. Two engaging pins 131-1 and 131-2 projecting radially from the third lens holder 13 project outward from guide grooves (through holes) 11A and 11E formed in the lens barrel 11, and are cam grooves of the cylindrical cam 15. 151 is engaged. Similarly, the two engagement pins 161-1 and 161-2 projecting in the radial direction from the second lens holder 16 project outward from the guide grooves 11C and 11F (through holes) formed in the lens barrel 11, and the cylindrical cam 15 The cam groove 151 is engaged.

  The 3rd lens holder 13 and the 2nd lens holder 16 are demonstrated in order based on FIG. 2 also with reference to FIG. Four guide rods 132-1 to 132-4 are formed on the peripheral portion of the third lens holder 13 at substantially equal intervals. These guide rods 132-1 to 132-4 are formed so as to be in sliding contact with guide grooves 11A, 11C, 11E, and 11G formed inside the lens barrel 11. From the two guide rods 132-1 and 132-3, the aforementioned engagement pins 131-1 and 131-2 protrude in the radial direction. Further, four receiving grooves 133-1 to 133-4 are formed on the periphery of the third lens holder 13 so as to be positioned between the guide bars 132. These receiving grooves 133-1 to 133-4 are formed to receive the guide rods 162-1 to 162-4 of the second lens holder 16 having the same structure.

  The second lens holder 16 has the same structure as the third lens holder 13. That is, four guide rods 162-1 to 162-4 are formed on the peripheral portion of the second lens holder 16. These guide rods 162-1 to 162-4 are formed so as to be in sliding contact with the remaining guide grooves 11B, 11D, 11F, and 11H formed inside the lens barrel 11. Pins 161-1 and 161-2 protrude in the radial direction from the two guide rods 162-1 and 162-3. In addition, receiving grooves 163-1 to 163-4 are formed in the peripheral portion of the second lens holder 16. These receiving grooves 163-1 to 163-4 are formed to receive the guide rods 132-1 to 132-4 of the third lens holder 13.

  The third lens holder 13 and the second lens holder 16 form a slidable state by engaging the guide rod and the receiving groove with each other. The guide rods (132 and 162) of the lens holders 13 and 16 in this state are slidably accommodated by engaging with guide grooves 11A to 11H formed on the inner surface of the lens barrel 11. That is, in this optical module, the guide rods (132 and 162) of the lens holders 13 and 16 are the first guide members, and the guide grooves 11A to 11H formed on the sliding surface of the lens barrel 11 are the second guide portions. A guide structure for holding the lens holders 13 and 16 slidably in the lens barrel 11 is realized. Therefore, the second lens holder 16 and the third lens holder 13 can be relatively moved in the optical axis direction without interfering with each other.

  Further, the characteristic structures of the second lens holder 16 and the third lens holder 13 shown in FIG. 2 will be described. The engaging pins 161-1 and 161-2 projecting from the second lens holder 16 are arranged in the opposite directions on the straight line 16L. First, by arranging a plurality of engagement pins having different directions in this way, the position of the second lens holder 16 is suppressed from being inclined with respect to the optical axis direction LD. The third lens holder 13 disposed below the second lens holder 16 has a similar structure. Also from the third lens holder 13, the engaging pins 131-1 and 131-2 are arranged in the opposite directions on the straight line 13L. Moreover, the straight line 16L and the straight line 13L are set to intersect each other.

  Therefore, the second lens holder 16 and the third lens holder 13 form a four-point support state by engaging the guide rod and the receiving groove with each other. Therefore, it is possible to more reliably suppress the optical axis of the lens held by both lens holders from being inclined with respect to the optical axis direction LD on the substrate side. In addition, since the lens holder is supported by the plurality of engaging pins as described above, the structure can be provided with the impact resistance at the time of dropping because the stress can be dispersed. In addition, since each lens holder 13 and 16 is formed with a guide rod and a receiving groove, they can be brought close to each other. In addition, since the guide rod extending from one lens holder does not interfere, the guide rod can be set longer.

  For example, by setting the lengths of the mutual guide rods 132 and 162 within a range in which the second lens holder 16 and the third lens holder 13 are moved, the second lens holder 16 and the third lens holder 13 are made light. No tilting with respect to the axial direction LD. Further, by setting the guide rods 132 and 162 to be long, light entering the lens barrel from the guide groove (11A or the like) provided on the lens barrel 11 side can be shielded. In addition, it is possible to obtain a dustproof property that prevents dust from entering the lens barrel 11.

  FIG. 3 is a diagram illustrating a cross-sectional configuration of the optical module in a state where the respective units illustrated in FIG. 1 are assembled. In FIG. 3, a cover 40 covering the outer periphery of the optical system unit 3 is shown. The cover 40 will be described later. With reference to FIG. 3, the structure in which the above-described cylindrical cam 15 is urged upward can be more clearly confirmed. That is, a male screw portion 117 formed on the upper portion of the lens barrel 11 and a female screw portion 197 formed on the inner wall of the first lens holder 19 meshing with the male screw portion 117 are shown. In this way, the uppermost first lens holder 19 is disposed on the upper portion of the lens barrel 11, and the cylindrical cam 15 is brought into contact with the first lens holder 19 by the biasing force of the coil spring 12, so that the lens position in the optical axis direction LD is reached. Will be determined. Therefore, the position of the third lens 14 can be set by the position of the first lens holder 19. Then, by rotating the first lens holder 19 with respect to the lens barrel 11, the back focus position can be positioned so as to match the light receiving surface of the CCD 2.

  Further, FIG. 3 shows that the engaging pin 131 protruding in the radial direction from the third lens holder 13 and the engaging pin 161 protruding in the radial direction from the second lens holder 16 can be confirmed. As described above, each of the lens holders 13 and 16 has two engagement pins, and FIG. 3 shows one of them. According to FIG. 3, it can be confirmed that the engaging pin 131 and the engaging pin 161 are engaged with the cam groove 151 formed on the inner wall of the cylindrical cam 15 disposed outside the lens barrel 11. Since the cylindrical cam 15 is urged upward by the coil spring 12 disposed at the lower part, the lens holders 13 and 16 move accordingly, and the position of the first lens holder 19 is used as a reference in the optical axis direction LD. The position is determined accurately. In relation to the claims, the second lens holder 16 and the third lens holder 13 correspond to a first lens holder, and the first lens holder 19 corresponds to a second lens holder.

(Cylindrical cam)
The cylindrical cam 15 employed in the optical system unit 3 exemplified in this embodiment has a characteristic configuration of a cam groove formed on the inner wall thereof. Further, this point will be described. FIG. 3 shows a more detailed configuration of the cylindrical cam 15. The cylindrical cam 15 incorporated in the optical system unit 3 is formed by two cam parts, an upper cam 15U and a lower cam 15L. When the optical module is downsized, the cylindrical cam 15 needs to be further downsized. However, as described above, the cam groove 151 for accurately guiding the third lens holder 13 and the second lens holder 16 in the optical axis direction LD must be formed on the inner wall of the cylindrical cam 15. It is extremely difficult to accurately form a narrow groove on the inner wall of a very small tubular member. Therefore, the present optical system unit 3 is manufactured by combining cam parts obtained by dividing the cylindrical cam 15.

  FIG. 4 is an enlarged view showing a state in which the cylindrical cam 15 shown in FIG. 3 is divided into two component parts, an upper cam 15U and a lower cam 15L. The cylindrical cam 15 is divided vertically by a cam groove 151 formed on the inner wall. As described above, the engagement pin 131 of the third lens holder 13 and the engagement pin 161 of the second lens holder 16 are engaged with the cam groove 151. A cam groove 151 is formed based on a cam curve (profile) for guiding these engagement pins. A dividing line 152 for the upper cam 15U and the lower cam 15L is set so that the shape of the cam curve appears at the end.

  Therefore, the cam groove 151 is formed in the portion where the upper and lower cams 15U, 15L are connected. With such a configuration, the upper cam 15U and the lower cam 15L are produced using two molds, and the cylindrical cam 15 can be produced by combining them. Therefore, even if the cam groove 151 is a thin groove, the cylindrical cam 15 can be manufactured relatively easily. Thus, this cylindrical cam 15 can be made thin and small by plastic injection molding using a mold or the like. In addition, since a process such as undercut is not required, a simple mold configuration can be obtained.

  As shown in FIG. 3, the heads of the engaging pins 131 and 161 have a substantially triangular cross section, and this portion serves as a cam follower and engages with the cam groove 151. The cam groove 151 is formed in a “V-shaped” cross section so as to correspond to the shape of the engagement pin. The shape of the cam groove 151 is shown in FIG. 4 so that the cam groove 151 is formed including a short vertical portion 153 at the center and inclined portions 154 provided above and below.

  As described above, the engaging pins 131 and 161 are inclined cams whose heads are inclined. A cam groove 151 is formed to guide the engagement pin as a cam follower. As described above, when the inclined cam is used for the head of the engaging pin, the diameter of the cylindrical cam 15 can be reduced while securing the thickness. Moreover, you may employ | adopt the planar cam which a cross section becomes a rectangle at the head of an engaging pin. In this case, the position system during the zoom operation can be enhanced.

  A recess 158 is formed from the upper surface of the upper cam 15U to the cam groove 151. In FIG. 4, only the recess 158 of the upper cam 15U can be confirmed. The recess 158 is a guide groove for guiding the engagement pin 161 of the second lens holder 16 to the cam groove 151 in the cylindrical cam. Since the engaging pins 161 are arranged in the reverse direction on a straight line, two concave portions 158 are formed in the upper cam 15U. However, when the third lens holder 13 and the second lens holder 16 are set on the lower cam 15L and then assembled so as to cover the upper cam 15U, it is not necessary to form the recess 158. In FIG. 4, the cam groove corresponding to the second lens holder and the cam groove corresponding to the third lens holder are connected by a guide groove for guiding the lens holder. The third lens holder is guided from the recess 158 to the cam groove for guiding the second lens holder, and further passes through the connected guide groove to reach the cam groove for guiding the third lens holder. Next, the second lens holder is guided from the recess 158 and set to the corresponding cam groove.

  The upper cam 15U is formed with a downward convex portion 156, and the lower cam 15L is formed with a receiving portion 157 for receiving it. These irregularities are similarly formed at opposite positions. The cylindrical cam 15 is manufactured by connecting the upper and lower cams 15U and 15L with these uneven portions 156 and 157 as reference positions. Therefore, the cylindrical cam 15 can be assembled with high accuracy, and the cam groove can be arranged on the inner surface with high positional accuracy. The upper cam 15U and the lower cam 15L can be integrally driven by fitting, but can be integrally formed by an adhesive or laser welding.

  FIG. 5 is a developed view showing that the shape of the cam groove 151 formed on the inner wall of the cylindrical cam 15 can be confirmed. According to FIG. 5, the state of the cam groove 151 formed on the inner wall of the cylindrical cam 15 can be confirmed more clearly. The cam groove 151 includes a cam groove 151-1 and a cam groove 151-2 defined by different cam curves. The cam groove 151-1 defines a zooming lens operation corresponding to the second lens holder 16. The cam groove 151-2 defines the lens operation of the correction system corresponding to the third lens holder 13. That is, the engagement pins 161-1 and 161-2 of the second lens holder 16 are engaged with the cam groove 151-1. Engagement pins 131-1 and 131-2 of the third lens holder 13 engage with the cam groove 151-2.

  5, it can be confirmed that the dividing line 152 between the upper cam 15U and the lower cam 15L is set so as to divide along the cam grooves 151-1 and 151-2. Further, according to FIG. 5, the relationship between the vertical portion 153 and the inclined portion 154 of the cam groove 151 can also be confirmed. The dividing line 152 includes a parallel dividing line portion 152LD that is parallel to the optical axis direction LD. By forming the dividing line 152 in this way, a useless space in the circumferential direction of the cylindrical cam 15 can be suppressed. However, when there is some margin in the circumferential direction, the dividing line portion 152LD may be inclined.

  FIG. 6 is a view schematically showing a modification of the cylindrical cam 15 formed by a plurality of cam parts. Although the cylindrical cam 15 shown in FIGS. 4 and 5 is composed of two upper and lower cams 15U and 15L, FIG. 6 shows an example in which three components are used. The cylindrical cam 15 is composed of three cam parts, an upper cam 15U, an intermediate cam 15M, and a lower cam 15L. The upper cam 15U and the intermediate cam 15M are separated by a dividing line 152-1, and the lower cam 15L and the intermediate cam 15M are separated by a dividing line 152-2.

  The dividing line 152-1 and the dividing line 152-2 are set based on different cam curves. These dividing lines also include a parallel dividing line portion 152LD that is parallel to the optical axis direction LD, thereby suppressing a useless space in the circumferential direction. In the dividing line 152-1, the curved portion 152-1CA is the original cam curve. Similarly, in the dividing line 152-2, the inclined straight portion 152-2CA is the original cam curve. The intermediate cam 15M is formed thinner than the upper and lower cams 15U and 15L, and when these are set, cam surfaces are formed at the upper and lower ends of the intermediate cam 15M. In the case of the cylindrical cam 15 shown in FIG. 6, the engaging pin from the lens holder of the correction system is set so as to abut on the curved portion 152-1CA. Similarly, the engaging pin from the variable magnification lens holder is set to contact the curved portion 152-2CA.

  Further, the upper cam surface and the lower cam surface can also be V-shaped in cross section, and the lens holder can be arranged on the cam surface by guiding the protrusion of the lens holder. In this case, the optical axis side end of the cam 15 passes through a recess (groove) for guiding the lens holder, a cam surface on which the other lens holder is disposed, or a recess for guiding the other lens holder. It is also possible to guide the lens holder.

  In the case of the cylindrical cam 15 shown in FIG. 6, different cam grooves can be formed overlapping in the height direction. Therefore, one type of cam groove can be arranged in the circumferential direction with a margin as compared with the case where cam grooves having different shapes are simultaneously arranged on one circumference shown in FIG. Therefore, since the cam rotation angle can be set large, the torque of the actuator can be reduced. Although FIG. 6 shows an example in which a cylindrical cam is constituted by three cam parts, it may be constituted by more divided parts. In the cylindrical cam 15 shown in FIG. 6, since three sets of cam curves are arranged on the same plane, the degree of freedom of the lens holder is limited, so that the angle of the lens holder with respect to the optical axis direction is stable. Have. For this reason, it is also possible to reduce the number of guide grooves.

  FIG. 7 is a view showing a preferable cam curve (profile) for defining a cam groove formed on the inner wall of the cylindrical cam 15. FIG. 7A shows a cam curve 151-1 CA that defines the cam groove 151-1 for the variable power lens. FIG. 5B shows a cam curve 151-2CA that defines the cam groove 151-2 for the correction system lens. That is, the second lens holder 16 is moved in the optical axis direction based on the cam curve 151-1CA. Based on the other cam curve 151-2CA, the third lens holder 13 is moved in the optical axis direction.

  More specifically, the engagement pins 161-1 and 161-2 protruding in the radial direction of the second lens holder 16 are moved in the optical axis direction by the cam groove 151-1 defined by the cam curve 151-1CA. Is done. The engagement pins 131-1 and 131-2 protruding in the radial direction of the third lens holder 13 are moved in the optical axis direction by the cam groove 151-2 defined by the cam curve 151-2CA. FIG. 7 illustrates a cam curve when a macro function is added to the telephoto side in addition to the zoom function.

  The optical module is miniaturized so that it can be mounted on a mobile phone or the like. When the zoom function is provided as described above, it is important to move each lens holder to an intended position with high accuracy. For this purpose, conventionally, a method of arranging a position detection member for confirming that the lens holder is in the wide-angle position or the telephoto position is generally employed. However, if the position detecting member is separately provided in this way, the optical module is increased in size, which is against the request for downsizing. Moreover, the optical module used for a mobile phone etc. is very small, and its perimeter is short with respect to the circumference angle of a cylindrical cam. Therefore, high accuracy is required to detect the position of the lens holder in the optical axis direction with respect to the rotation angle. However, it is difficult to provide a position detection member. The cam curve shown in FIG. 7 makes it possible to achieve desired characteristics without detecting the position at the wide-angle end and the telephoto end by providing flat portions on the cam curves of the variable magnification system and the correction system.

  In this optical system unit 3, a rack portion 159 is fixed to the outer periphery of the cylindrical cam 15, and the driving force of the actuator is transmitted by a gear meshing with the rack portion 159. Even if gears with high dimensional accuracy are used, it is difficult to eliminate the effects of backlash. There are also other parts and assembly errors. In this optical unit 3, since there is no position detection member, the position of the rotating cam cannot be detected with high accuracy. When the cylindrical cam 15 is rotated between the wide-angle end and the telephoto end by the zoom operation, the desired wide-angle end or telephoto is affected by the initial position shift and backlash, despite being rotated by the actuator by a predetermined angle. There is a possibility that the cylindrical cam is not rotating at the end position.

  Therefore, in the present embodiment, as shown in FIG. 7, at both ends of the curved portion (zoom portion) for zooming the lens, that is, at the wide-angle end (wide end) and the telephoto end (tele end), orthogonal to the optical axis direction LD. A cam curve having a flat portion having a predetermined length is adopted. In other words, in the present embodiment, a cam curve having such a flat portion is employed as the cam curve of the variable power system and the correction system of the cylindrical cam 15. Accordingly, even if the position detection member does not perform highly accurate position detection, the performance at the wide-angle end or the telephoto end can be achieved if the lens holder is provided on the flat portion. Considering the position of the lens holder, when the lens holder is at the flat part at the wide-angle end, the actuator is driven in consideration of the distance of the flat part, so that it moves to the flat part at the telephoto end even if the imaging distance is shifted. By doing so, the performance at the telephoto end can be maintained. Therefore, it is possible to eliminate the influence of backlash, assembly error, and the like, and to achieve predetermined performance stably at the wide angle and telephoto positions.

  A case of moving from the wide-angle end to the telephoto end will be described as an example. In this optical system, in order to detect the initial position, the cylindrical cam is moved to the wide-angle end side, and a drive pulse is given to the actuator by a predetermined number of pulses from the position where the cylindrical cam stops at the rotation limit of the cylindrical cam. The position on the flat part where the rotating cam is returned to the telephoto side is set as the initial position. Therefore, it is expected that the initial position has a position error. For example, assume that the rotation angle from the wide-angle end to the telephoto end is 500 pulses, and the rotation angle of the flat portion is 50 pulses. When the initial position is a position of 25 pulses from the wide angle end, in order to move to the telephoto end, a 550 pulse drive pulse is applied with the target position on the flat portion of 25 pulses from the telephoto end. In other words, if it moves within 25 pulses before and after the target value, the cylindrical cam is driven to rotate at the telephoto end, and the desired movement is achieved.

  Further, the cam curve illustrated in FIG. 7 has a macro photographing curve and a flat portion on the telephoto side. Also in this case, since the macro state is entered after passing through the flat portion at the telephoto end, focusing is performed with high accuracy. Furthermore, since a predetermined function can be achieved at the flat portion, stable operation is possible.

  As described above, the lens position shift at the wide-angle position, the telephoto position, and the macro position can be suppressed by adding a flat portion having a predetermined length to a predetermined position of the cam curve. In this configuration, there is no need to newly provide a position detection member for confirming that there are lenses at the wide-angle position, the telephoto position, and the macro position. Therefore, it is possible to provide an optical module capable of performing photographing using a zoom function or a macro function stably with a wide angle and a telephoto structure with a simple configuration that is reduced in size and cost. If a macro cam curve is formed continuously on the telephoto flat portion as shown in FIG. 7, the macro function can be stably used by absorbing the displacement of the cylindrical cam on the macro side. However, since the macro function is not essential for the present optical module, it may be a cam curve that does not include a macro curve portion.

(Positioning structure)
Furthermore, this optical module has an excellent feature with respect to the assembly structure. This point will be described below. In the present optical module, the cylindrical cam 15 is driven by an actuator, and the third lens holder 13 and the second lens holder 16 move in the optical axis direction. In the optical module, the lens barrel 11 is accurately positioned with respect to the CCD 2 on the substrate, and then the cylindrical cam 15 is disposed on the outer periphery thereof, and the actuator is provided so that the driving force is efficiently transmitted to the cylindrical cam 15. Need to be placed.

  As an arrangement method of the actuator, an assembly form in which the optical system unit 3 and the actuator shown in FIG. 1 are individually configured and combined on a substrate to form one module is conceivable. In the case of adopting this form, a method of providing a positioning hole or pin on the substrate 1 side or positioning a guide pin for positioning is used in order to position the actuator.

  On the other hand, for the optical system unit 3, the position of the lens barrel 11 that is first fixed to the substrate 1 is a reference. The lens barrel 11 is positioned with respect to the optical axis (optical center) of the CCD 2. Specifically, the lens barrel 11 is arranged so as to be focused on the CCD 2 on the substrate. However, in the actual assembly work, an attachment error of the CCD 2 or the lens barrel 11 occurs with respect to the design position. If this error exceeds the allowable range, the position of the lens barrel 11 is adjusted so as to match the optical center of the CCD 2, or the lens barrel 11 is positioned based on the outer shape of the CCD 2 to eliminate the error. It is necessary to.

  Further, when the configuration in which the optical system unit 3 and the actuator are individually configured and assembled to the substrate is adopted, it is assumed that the lens barrel 11 is disposed at a predetermined position on the substrate 1. The placement of the actuator has been determined. However, as described above, the position of the lens barrel 11 often shifts during actual assembly. Thus, when the position of the lens barrel 11 is shifted, the position of the cylindrical cam 15 set on the outer periphery thereof is also shifted. If the position of the cylindrical cam shifts, the relative position with respect to the actuator deviates from the designed range, and the predetermined performance as the optical module cannot be maintained.

  Therefore, the present optical module employs a configuration in which the optical system unit 3 and the actuator are positioned via a cover that covers the optical system unit 3. If such a configuration is adopted, even if the position of the lens barrel 11 is shifted, the actuator position moves with maintaining the relative positional relationship with the lens barrel 11 accordingly. It becomes an easy structure to implement | achieve. Further, when this configuration is adopted, the cover for the optical system unit 3 and the cover for the actuator can be integrated, so that the space can be saved.

  With reference to FIG. 8 and FIG. 9, the positioning structure using the cover 40 employ | adopted with this optical module is demonstrated. FIG. 8 is a diagram illustrating a driving unit that drives the optical system unit 3 and a cover that is set on the optical system unit 3. FIG. 8 shows the first lens 18 and the first lens holder 19 positioned on the upper side so that the relationship with the optical system unit 3 described above can be confirmed. FIG. 9 is a view showing a cross-sectional configuration of an optical module in a completed state in which the optical system unit 3 and the motor 30 as an actuator are assembled.

  In this optical module, the cylindrical cam 15 is driven by the motor 30. In FIG. 8, each element of the motor 30 is shown in an exploded state. The motor 30 is assembled using the cover 40 and the substrate 31, and the cover 40 is set on the substrate 1 of the optical system unit 3. The motor 30 includes a pair of coils 32 and a stator 33, and has a rotor 35 at the center.

  A shaft 41 fixed to a predetermined position of the cover 40 and a shaft for the rotor 35 are arranged coaxially, and the rotor 35 is set to rotate about the shaft 41. The shaft 41 is set in a hole 51 formed in the cover 40. A gear 36 that rotates integrally with the rotor 35 is provided. A shaft 42 is fixed at another position of the cover 40, and a gear 43 that meshes with the gear 36 and a gear 44 that rotates together with the gear 43 are provided on the shaft 42. A rack portion 159 formed on the outer periphery of the cylindrical cam 15 meshes with the gear 44. The shaft 42 is set in a hole 52 formed in the cover 40.

  FIG. 9 shows a state in which the parts shown in FIG. 8 are assembled. As shown in FIG. 9, the first lens holder 19 is fitted into an opening 45 formed in the cover 40. Accordingly, the lens barrel 11 and the cylindrical cam 15 are positioned with respect to the cover 40 via the first lens holder 19. Further, the shafts 41 and 42 are positioned at predetermined positions of the cover 40. As shown in FIG. 8, the motor 30 is positioned with respect to the shaft 41. In this structure, the positional relationship between the lens barrel 11 and the cylindrical cam 15 side and the motor 30 side is determined via the cover 40. Therefore, even if the setting position of the lens barrel 11 is deviated, the position on the motor 30 side also moves corresponding to the position of the optical system unit 3 via the cover 40. That is, the relative positional relationship between the cylindrical cam 15 and the motor 30 is maintained, and no deviation occurs.

  As described above, in the present optical module, the optical system unit 3 side and the drive unit side are positioned via the cover 40, so that the driving force of the rack 30 and the motor 30 provided on the outer periphery of the cylindrical cam 15 is transmitted. No positional deviation occurs between the gears 36, 43, and 44. Therefore, by adopting this structure, the present optical module can efficiently transmit the driving force of the motor as designed.

  The preferred embodiment of the present invention has been described in detail above, but the present invention is not limited to the specific embodiment, and various modifications can be made within the scope of the gist of the present invention described in the claims.・ Change is possible.

It is the disassembled perspective view shown so that the inside of the optical module which concerns on embodiment could be confirmed. It is the figure which expanded and showed the 3rd lens holder and 2nd lens holder which were shown in FIG. It is the figure which showed the cross-sectional structure of the optical module of the state which assembled | attached each part shown in FIG. It is the enlarged view which showed the state which divided | segmented the cylindrical cam shown in FIG. 3 into two component parts. It is the expanded view shown so that the cam groove formed in the inner wall of a cylindrical cam could be confirmed more clearly. It is the figure which showed typically the modification of the cylindrical cam formed by several cam components. It is the figure which showed the preferable cam curve (profile) in order to prescribe | regulate the cam groove formed in the inner wall of a cylindrical cam. It is the figure shown about the drive part which drives an optical system unit, and the cover set on an optical system unit. It is the figure which showed so that a cross-sectional structure could be confirmed for the optical module of the completion state which assembled | attached the optical system unit and the motor. It is the figure shown about the lens drive device of the conventional small camera.

Explanation of symbols

1 substrate 2 CCD
3 Optical system unit 11 Lens barrel 11A to 11H Guide groove 11A, 11E Through hole (for third lens holder)
11B, 11F Through hole (for second lens holder)
12 Coil spring 13 Third lens holder 131 Engaging pin 15 Cylindrical cam 151 Cam groove 16 Second lens holder 161 Engaging pin 19 First lens holder LD Optical axis direction

Claims (6)

A first lens holder, a second lens holder positioned closer to the object side than the first lens holder, and circumscribing the first lens holder, and the first lens holder is slidable in the optical axis direction. An optical module including a lens barrel held on the outer periphery of the lens barrel and a cylindrical cam disposed on an outer periphery of the lens barrel and changing a position of the first lens holder,
A protrusion member extending from a side surface of the first lens holder;
The lens barrel is formed with a through hole that allows movement of the protruding member in the optical axis direction,
A cam surface for guiding the protruding member to a predetermined position is formed on the inner wall of the cylindrical cam.
The second lens holder is fixed to an upper end portion of the barrel, and has a sliding surface for positioning the cylindrical cam in the optical axis direction,
An optical module, wherein an elastic member that urges the cylindrical cam toward the sliding surface of the second lens holder is disposed. 2. The optical module according to claim 1, wherein the second lens holder is screwed to the upper end portion of the lens barrel so as to be movable in the optical axis direction. 3. The optical module according to claim 1, wherein the elastic member is a ring-shaped conical coil spring or a bamboo child spring disposed under the cylindrical cam. 4. The optical module according to claim 1, wherein the first lens holder includes a plurality of the protruding members. The optical module according to claim 1, wherein a plurality of the first lens holders are provided. A portable electronic device comprising the optical module according to claim 1.

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