JP2010191061A - Collapsible mount type lens barrel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve resistance to a shock in a collapsible mount type lens barrel. <P>SOLUTION: A cam ring 14 is not supported by fitting a cam follower in a cam groove, but the cam ring 14 is held to be rotatable by a straight advance base 15. In such a case, the cam ring 14 is held by a plane part 15b and a pawl 15d of the straight advance base 15, whereby the movement of the cam ring 14 in an optical axis direction is regulated. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a retractable lens barrel, and more particularly to a countermeasure technique against an externally applied impact.

  In recent years, there has been a strong demand for miniaturization of cameras (digital cameras), and many small cameras have been created to meet such demands. However, there is an adverse effect that the holdability of the camera is impaired due to being too small. In the worst case, if the camera is not sufficiently held, the user may accidentally drop the camera.

  In view of this, there has conventionally been proposed a camera that has improved resistance to external impacts so that the user cannot easily drop the camera and damage it. Many cameras of this type employ a so-called bendable lens barrel that bends a part of the optical path of the imaging optical system, and the lens barrel does not protrude from the camera body (Patent Literature). 1).

  This is because if the retractable lens barrel that has been generally used is used, the camera body becomes larger by covering the front of the lens barrel with the exterior to protect the lens barrel. Therefore, a bending lens barrel is employed. Since the bent lens barrel remains completely inside the camera body during operation, the lens barrel is protected by the camera body even if the user accidentally drops the camera.

  However, the bending lens barrel has its storage area restricted by the thickness of the camera body, so that the lens naturally has a small diameter, and the optical path is bent halfway, making it difficult to obtain the desired optical performance. there were.

  On the other hand, in the retractable lens barrel, although there is a restriction on the thickness in the optical axis direction, a relatively large space can be secured in the radial direction of the optical axis. Alternatively, the optical axis of the optical system from the subject to the image sensor can be made straight. Therefore, in the retractable lens barrel, desired optical performance can be obtained relatively easily.

  Thus, the retractable lens barrel is excellent from the viewpoint of ensuring optical performance. However, the retractable lens barrel has the following problems from the viewpoint of resistance to external impacts. That is, the retractable lens barrel is generally held by a cam groove and a cam follower that fits into the cam groove. For this reason, in the retractable lens barrel, even if it is avoided that an external force is directly applied to the lens barrel by covering the lens barrel with the camera exterior, the cam follower drops from the cam groove due to a large impact such as dropping. There was a case.

  Japanese Patent Application Laid-Open No. 2007-334256 describes a camera having a structure highly resistant to a drop impact, but does not clearly describe the structure of the lens barrel.

JP 2007-334256 A Japanese Patent Laying-Open No. 2005-215079

  The present invention has been made under such a technical background, and an object thereof is to improve resistance to impact in a retractable lens barrel.

  In order to achieve the above object, the barrel lens barrel according to the present invention is capable of rotating a cam ring formed with a cam groove for moving the lens in the optical axis direction and restricting movement in the optical axis direction. A second holding member that holds the focus lens is located on the inner peripheral portion of the base portion of the holding member, and the second holding member holds the focus lens. It has the support part which supports the front-end | tip of a lead screw for driving to an optical axis direction rotatably.

  According to the present invention, the cam ring is held by the holding member without being held (supported) by the cam follower, and is held in a form that restricts movement in the optical axis direction. The risk of falling off is reduced.

  The second holding member supports the tip of the lead screw for driving the focus lens in the optical axis direction so as to be rotatable, so that the tip of the lead screw is in a free state. . Thereby, even if a strong external impact is applied, the leading end side of the lead screw does not oscillate violently, and the possibility of degradation of optical performance, breakage of components, etc. is reduced.

  With these actions, according to the present invention, it is possible to improve the resistance to impact in the retractable lens barrel.

It is sectional drawing in the optical-axis part of the lens barrel which concerns on embodiment of this invention. It is a disassembled perspective view of the periphery of the cam ring holding member of the lens barrel of FIG. It is sectional drawing in the optical axis part of the focus mechanism part of the lens barrel of FIG. It is sectional drawing in the part of the shaft of a guide shaft, a lead screw, and a motor of the focus mechanism part of the lens barrel of FIG. It is sectional drawing which shows the positional relationship of a focus holding member and a cam ring holding member. It is a perspective view which shows a focus holding member. It is an expanded view of the inner surface of a cam ring. It is sectional drawing of a cam ring holding member and a cam ring. It is sectional drawing in the optical axis direction of the guide groove and introduction groove | channel of a 2nd group lens barrel. It is sectional drawing in the orthogonal direction with the optical axis which shows the width | variety of a guide groove and an introduction groove | channel.

  FIG. 1 is a cross-sectional view showing a lens barrel according to an embodiment of the present invention. In FIG. 1, 1 is a first group lens, 2 is a second group lens, and 3 is a third group lens. Reference numeral 11 denotes a first group lens holder that holds the second group lens, reference numeral 12 denotes a second group lens holder that holds the second group lens, and reference numeral 13 denotes a third group lens holder that holds the third group lens (focus lens).

  These first to third group lenses 1 to 3 function as a focal length adjusting optical system, mainly changing the zoom magnification by adjusting the positions of the first group lens 1 and the second group lens 2, and focusing by adjusting the position of the third group lens. Adjustments are made. The second group lens holder is held by the second group base 19 and is subjected to camera shake correction by moving on a plane orthogonal to the optical axis by a mechanism (not shown). Reference numeral 20 denotes a shutter blade / aperture blade for adjusting incident light.

  A cam ring 14 holds the first group lens holder and the second group base, and cam grooves 14a and 14b are formed on the inner periphery thereof. The first group lens holder 11 and the second group lens holder 12 each have a cam follower (see FIG. 2) (see reference numeral 11a in FIG. 2), and these cam followers are fitted to the cam grooves 14a and 14b on the cam ring 14. It is held and moves in the optical axis direction by the rotation of the cam ring 14.

  Hereinafter, a unit that is integrally held by the first group lens holder 11 is referred to as a first group barrel, and a unit that is integrally held by the second group base is referred to as a second group barrel.

  Reference numeral 15 denotes a rectilinear base that holds the cam ring 14 rotatably and restricts the movement of the first lens group holder 11 and the second lens group holder 12. Reference numeral 16 denotes a CCD holder that holds the image sensor 17 (for example, a CCD) and serves as a base of a lens barrel. A cover 27 covers the outermost periphery of the lens barrel and is fastened to the CCD holder 16.

  The cross-sectional shape of the tip of the CCD holder 16 is an L-shape 16a, and a part of the circumferential direction is an elastic portion having elasticity. This elastic portion is in contact with the projecting portion 14e of the cam ring 14, and acts so that the cam ring 14 is pushed toward the CCD to be displaced. As a result, it is possible to eliminate the backlash generated in the optical axis direction of the cam rings 14a and 14b and the rectilinear base 15.

  As shown in FIG. 1, the third group lens holder (second holding member) 13 that holds the third group lens (focus lens) is located in the inner peripheral portion of the base portion 15a.

  Next, the rectilinear base 15, the cam ring 14, and the lens barrels 1 to 3 of each group will be described in detail with reference to FIG. FIG. 2 is an exploded view of the lens barrel viewed obliquely from the subject side. The cam ring 14 is assembled from the front with respect to the rectilinear base 15, and the first group lens holder 11 and the second group base 19 lens barrel are assembled from the rear.

  The rectilinear base 15 is roughly divided into three parts: a cylindrical part 15a, a flat part 15b, and a base part 15c. A cam ring 14 is mounted on the outer periphery of the cylindrical portion 15 a of the rectilinear base 15, and the cylindrical portion 15 a functions as a fitting portion for fitting the cam ring 14.

  The cam ring 14 is restricted from moving in the optical axis direction by the flat surface portion 15 b and the claw portion 15 d of the rectilinear base 15. As a result, the cam ring 14 only rotates around the optical axis and does not move in the optical axis direction. The base portion 15c is fixed to a CCD holder 16 that serves as a base for the entire lens barrel.

  On the inner periphery of the cam ring 14, a cam groove 14a that guides the movement of the first group barrel in the optical axis direction and a cam groove 14b that guides the movement of the second group barrel in the optical axis direction are provided. The followers of the first group barrel and the second group barrel are fitted in the cam grooves 14 a and 14 b, respectively, so that the first group barrel and the second group barrel are held by the rectilinear base 15.

  In this case, a part of the first group lens barrel and the second group lens barrel are fitted into the rectilinear grooves 15e and 15f provided in the rectilinear base 15, so that the rotation is restricted. As the cam ring 14 rotates, it moves only in the optical axis direction.

  The cam follower of the first group barrel is composed of three pins 11 a fixed to the first group lens holder 11. Further, the cam follower of the second group barrel includes two pins 19a fixed to the second group base 19 and one movable pin 19b urged outward by a compression spring (not shown). The reason why one of the three pins as the cam follower of the second group barrel is a movable pin is that the second group lens 2 has a great influence on the optical performance, so that there is no gap play with the cam groove 14b. This is to reduce performance fluctuations.

  The cam ring 14 is rotationally driven by a motor 22 (see FIG. 3) via a gear 14c provided on the outer periphery thereof. In this case, the light shielding state of the detection unit of the photo interrupter 18 is switched by the flag 14d provided on the outer periphery of the cam ring 14, and thereby the reference position of the rotation angle of the cam ring 14 is detected.

  Next, the focus drive mechanism will be described with reference to FIGS. FIG. 3 is a cross-sectional view in a direction passing through the optical axis and orthogonal to the cross section of FIG. FIG. 4 is a cross-sectional view of the guide shaft, the lead screw, and the motor shaft of the focus mechanism.

  In FIG. 3, 20 is a guide shaft for holding the third group lens holder 13 so as to be movable back and forth in the optical axis direction, 21 is a lead screw for driving the third group lens holder 13 forward and backward in the optical axis direction, and 22 is a motor. Reference numeral 23 denotes a coil spring for shifting the third group lens holder 13 to one side. In the present embodiment, the coil spring 23 is used in a pulled state.

  As shown in FIG. 1, in FIG. 4, reference numeral 25 denotes a nut that meshes with the lead screw 21. The nut 25 is pressed against the receiving surface of the third group lens holder 13 by the tension of the coil spring 23. 13a is a sleeve fitted to the guide shaft 20, and the sliding load is reduced by limiting the fitting portion to two places as shown in FIG.

  A spring 23 is hooked on the hook 13 b of the third group lens holder 13, and the other end of the spring 23 is hooked on the hook 16 a of the CCD holder 16. The rotation of the pinion gear 22a fixed to the rotation shaft of the motor 22 is transmitted to the gear 21a fixed to the lower end of the lead screw 21 by a relay gear (not shown).

  In the focus mechanism having such a configuration, when the motor 22 rotates, the lead screw 21 rotates through the relay gear, and the nut 25 moves forward and backward in the optical axis direction by the effect of the feed screw. In this case, focusing is performed by moving the third group lens holder 13 back and forth in the optical axis direction together with the nut 25.

  As shown in FIG. 4, the lower end of the guide shaft 20 is fixed to the CCD holder 16, and the upper end of the guide shaft 20 is held by a focus holding member (second holding member) 26. The lower portion of the lead screw 21 is slidably fitted into the round hole 16b of the CCD holder 16, and the upper portion of the lead screw 21 is slidably fitted to the round hole 26a of the focus holding member 26 and rotated. Held possible.

  That is, the round hole 26a of the focus holding member 26 functions as a support portion that supports the tip of the lead screw 21, and avoids the tip of the lead screw 21 from being free and swinging due to an external impact or the like. Acts like

  Further, the lower end portion 21b of the lead screw 21 has a spherical shape, and determines the position in the optical axis direction by making point contact with the cover 27. Similarly, the upper end portion 21c of the lead screw 21 has a spherical shape, and is in point contact with the upper surface of the focus holding member 26. However, since the lead screw 21 is biased downward in the figure in use, there is a gap between the spherical surface at the upper end and the bottom surface of the round hole 26b of the focus holding member 26 so that they do not come into contact with each other. Yes.

  The effect of increasing the resistance to impact in the lens barrel configured as described above will be described.

  First, regarding the focus drive mechanism, as described above, the tip of the guide shaft 20 and the lead screw 21 is held by the focus holding member 26 to improve the impact resistance.

  Along with the recent miniaturization of the camera, a structure is often used in which the guide shaft 20 and the lead screw 21 hold the root side, that is, the optical axis direction CCD side but not the tip side. This structure is effective for miniaturization, but when a strong external impact is applied, the free end is shaken violently, causing optical performance deterioration due to tilting of the guide shaft, etc., and component damage due to nut biting etc. There was a possibility. Therefore, in the present embodiment, the tip of the guide shaft 20 and the lead screw 21 is held to improve impact resistance.

  Next, with respect to the structure of the lens barrel, as described above, the cam ring 14 is held by the rectilinear base 15, and the cam ring 14 is configured to perform only rotational movement, thereby improving impact resistance. Conventionally, the retractable lens barrel has a structure in which the cam ring is moved in the optical axis direction. In this case, the cam ring is configured to be fitted with a cam groove of an adjacent fixed cylinder by a cam follower.

  When the cam ring or the adjacent fixed cylinder is deformed by an external impact, the cam follower falls off the cam groove relatively easily. In particular, since the cam ring holds a lens holding member such as a first group barrel or a second group barrel inside, the impact force applied to the total mass is increased. Therefore, in the present embodiment, the cam ring 14 is rotatably held by the rectilinear base 15, but by restricting the movement of the cam ring 14 in the optical axis direction, the support by the cam follower fitting that is vulnerable to impact is eliminated. ing.

  In addition, the straight base 15 has three bent cross-sectional shapes as described above, thereby increasing the rigidity and improving the impact resistance. The diameter of the base portion 15c of the rectilinear base 15 is made equal to the outer periphery of the cam ring 14, thereby preventing an increase in the size of the lens barrel while increasing rigidity.

  Further, in order to increase the rigidity of the focus holding member 26 shown in FIG. 5, a rib shape 26b is provided on the outer periphery thereof. Further, the fixed portion 26c of the focus holding member 26 shown in FIG. 6 is arranged using a space outside the straight advance base 15a and inside 15c. As a result, the resistance to impact is improved without increasing the size of the lens barrel.

  Next, assembly in the lens barrel as described above will be described. FIG. 7 is a developed view of the inner surface of the cam ring.

  First, as shown in FIG. 7, the cam groove 14b for the second group lens barrel of the cam ring 14 penetrates the end surface in the CCD direction, so that the claw portion 15d of the rectilinear base 15 is inserted therethrough. Then, the claw portion 15d is advanced along the cam groove 14b. The cam groove 14b for the second group lens barrel also penetrates the end surface on the subject side, and the claw portion 15d reaches the end surface of the cam ring 14 through the through groove 14e. In this way, the cam ring 14 is assembled to the rectilinear base 15.

  Next, the first group lens barrel and the second group lens barrel are assembled in the cam grooves 14 a and 14 b of the cam ring 14. A cam groove 14a for the first group lens barrel is also extended through the end surface of the cam ring 14 on the CCD side, and the first group lens barrel with the through groove 14g (hereinafter referred to as an introduction groove) as an insertion port. Insert the cam follower. The second group lens barrel is inserted through the introduction groove 14h, that is, the introduction portion.

  At this time, since the cam ring 14 is positioned on the tip side of the rectilinear base 15, when inserting the first or second lens barrel, the cam ring 14 must be pushed into the inner side of the rectilinear base 15 for assembly. hard.

  Therefore, in the present embodiment, as shown in FIG. 8, guide grooves 15g and 15h obtained by extending rectilinear grooves 15e and 15f (see FIG. 2) are provided inside the base portion 15c of the rectilinear base 15. As described above, the guide grooves 15g and 15h are provided, and the insertion is facilitated by matching the phase with the introduction groove (introduction portion) of the cam ring 14.

  Next, the lens barrels of each group are pushed along the introduction groove toward the tip of the tension of the coil spring 23. When the lens barrel reaches the wide end groove shown in the development view of FIG. Complete.

  In this installation, since the depth of the straight base 15 is deep, it may be difficult to confirm whether or not the lens barrels of each group are pushed in all the way. Since the follower pin of the first group lens barrel is a fixed pin, there is a slight gap between the cam groove and the rectilinear base 15 so that it will naturally fall and reach the end.

  However, since one follower pin of the second group lens barrel is a movable pin as described above, the follower pin is stretched with respect to the guide groove or the introduction groove and is held at any position. For this reason, it is difficult to know whether the cam follower has transferred from the straight base 15 to the cam ring. In the present embodiment, this problem is solved as follows.

  FIG. 9 shows a cross-sectional view of a plane passing through the guide groove and the introduction groove and including the optical axis. FIG. 9 shows a state where the second group lens barrel (the cam follower) is transferred to the introduction groove 14 h of the cam ring 14. The bottom surface of the guide groove 15h of the rectilinear base 15 is not uniform in depth as shown in FIG. In other words, the bottom surface of the guide groove 15h is the deepest portion 15i at the entrance, the innermost portion connected to the cam ring 14 is the shallowest portion 15k, and the space between the deepest portion 15i and the shallowest portion 15k is gentle. The slope is 15j.

  The bottom surface 14i of the introduction groove 14h of the cam ring 14 has a groove depth that is deeper than the guide groove bottom surface 15k, resulting in a step. With such a configuration, the compression spring 19c is gradually charged by the slope 15j, and the spring pressure is released when it exceeds the step between the introduction groove 14h and the guide groove 15h. The operator can sense the resistance to the vibration and pushing at that time, and sensibly grasp the transfer of the cam follower from the guide grooves 15f and 15g to the cam grooves 14a and 14b.

  In the present embodiment, since the introduction groove 14h for the second group lens barrel is short, the second group lens barrel (the cam follower) can smoothly transition to the cam groove 14b after the transfer to the cam ring 14. it can.

  In the present embodiment, the above configuration is applied only to the second group lens barrel, but the same configuration may be applied to the first group lens barrel. In this case, since the cam follower of the first group lens barrel is a fixed pin, the rectilinear base 15 is elastically deformed so that the cam follower of the first group lens barrel does not bite into the groove at the shallowest part of the introduction groove. It is desirable to do.

  Further, in the present embodiment, when the cam follower moves from the guide groove 15f to the introduction groove 14f, the widths of both grooves are made different so that the corresponding groove can be smoothly transferred even if the rotational phase of the groove is slightly shifted. (See FIG. 10). FIG. 10 is a cross-sectional view from the subject direction, showing a cross section orthogonal to the optical axis and passing through the introduction groove.

  In this way, by expanding the width of the introduction groove 14f beyond the width of the guide groove 15f, the cam follower can smoothly transfer from the guide groove 15f to the introduction groove 14f even if the introduction groove 14f and the guide groove 15f are slightly displaced. .

  In this embodiment, since the first group lens barrel is incorporated first, the groove widths of the introduction grooves 14f for the first group lens barrel are made different. If the first group lens barrel is incorporated, the rotational phases of the cam ring 14 and the rectilinear base 15 are determined. Therefore, even if the width of the guide groove 14h of the second group lens barrel to be assembled later and the groove width of the introduction groove 15h coincide with each other, the assemblability is not affected.

DESCRIPTION OF SYMBOLS 1 ... 1 group lens 2 ... 2 group lens 3 ... 3 group lens 11 ... 1 group lens holder 12 ... 2 group lens holder 13 ... 3 group lens holder 14 ... cam ring 14a ... 1 group cam groove 14b ... 2 group cam groove 14f 14g: introduction groove 15 ... straight advance base 15d ... claw portion 15f, 15g: guide groove 19 ... second group base 20 ... guide shaft 21: lead screw 26 ... focus holding member 26b ... rib shape

Claims (5)

  A holding member that holds a cam ring formed with a cam groove for moving the lens in the optical axis direction in a form that allows rotation and restricts movement in the optical axis direction; A second holding member that holds the focus lens is located on the inner peripheral portion, and the second holding member rotatably supports the tip of a lead screw for driving the focus lens in the optical axis direction. A retractable lens barrel having a support portion.   The holding member has a cylindrical shape, and includes a fitting portion for fitting the cam ring, a base portion having a larger diameter than the fitting portion, and a claw portion, and the base portion and the claw portion The collapsible lens barrel according to claim 1, wherein movement of the cam ring in the optical axis direction is regulated in a form in which the fitting portion is sandwiched.   The holding member has a guide groove for guiding the lens holding member that holds the lens in the optical axis direction, and the cam groove of the cam ring has a cam follower formed on the lens holding member that holds the lens. The retractable lens mirror according to claim 1, further comprising an introduction portion for introduction, wherein a bottom surface of the guide groove has a slope shape with a shallow groove toward the introduction portion. Tube.   The collapsible lens barrel according to claim 3, wherein a bottom surface of the entrance of the guide groove of the holding member is deeper than a bottom surface of the inner deep portion of the guide groove to form a step.   4. A retractable lens barrel according to claim 3, wherein the groove width of the cam groove introduction portion of the cam ring is wider than the groove width of the guide groove.

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