JP2011027837A - Lens barrel - Google Patents

Abstract

Provided is a lens barrel capable of reducing the driving load of a feeding cam mechanism mounted on a lens barrel and stabilizing zoom drive and reducing noise.
A cam ring 21 having a cam groove 21b formed on a peripheral surface, and a holding portion 11d for holding a spherical engagement member 17 engaged with the cam groove 21b are provided, and a lens holding unit having a lens therein is provided. A lens barrel that includes a frame 11 and includes a cam mechanism that moves the cam ring 21 forward and backward along the cam groove 21b in the optical axis direction of the photographing optical system. When the ring 21 and the lens holding frame 11 are in a predetermined positional relationship, the groove engages deeper than the cam groove so that the ring 21 can pass between the cam ring 21 and the lens holding frame 11 and reach the holding part 11d. A member built-in passage is provided.
[Selection] Figure 9

Description

  The present invention relates to a lens barrel that is zoom-driven by a cam mechanism, and more particularly to a lens barrel that uses a ball follower as a follower engaged with a cam groove.

  In general, optical devices such as digital cameras having a zoom lens barrel are widely used. Such a zoom lens barrel uses a cam mechanism for driving the lens holding frame to advance and retract in the direction of the optical axis in accordance with a cam groove provided in the cam barrel in order to perform zoom extension and retraction operations. There is.

  In such a zoom lens barrel cam mechanism, an actuator such as a DC motor is used as a drive source, and the rotation is transmitted to a moving cam ring having a cam groove on the inner periphery through a speed reduction system. . A follower pin fixed to the lens holding frame is slidably inserted into the cam groove of the moving cam ring.

  In such a zoom lens barrel cam mechanism, the cam groove is rotated together with the moving cam ring by rotating the moving cam ring by a driving source. Then, there has been proposed one in which the follower pin is moved along the rotating cam groove so that the lens holding frame provided with the follower pin is zoom-driven in the optical axis direction (see, for example, Patent Document 1).

JP 09-2111292 A

  In recent years, the barrier between still images and moving images in a digital camera has become ambiguous, and there is an increasing demand for enabling the digital camera to shoot moving images. Furthermore, there is an increasing demand for enabling zoom driving and focus driving during moving image shooting with a digital camera.

  However, such a conventional zoom lens barrel cam mechanism is driven by friction generated when the follower pin fixed to the lens holding frame slides in the cam groove when the zoom is driven, and the cam groove and the follower pin rub against each other. The load was great. Furthermore, such a conventional zoom lens barrel cam mechanism has a problem that a large amount of sliding noise is generated when the lens holding frame stick-slip or parts are rubbed during zoom driving.

  Also, when shooting a movie with a digital camera, images and sound are always recorded during shooting, so it is possible to prevent the zooming operation from becoming unstable and making the movie difficult to see, and to prevent sliding sounds from being recorded. There is a need. For this reason, in a digital camera equipped with such a conventional zoom lens barrel cam mechanism, the zoom drive speed must be sufficiently reduced so as not to affect moving image shooting, and zoom performance deteriorates. There was a problem.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a lens barrel that can reduce the driving load during zoom driving and stabilize zoom driving and reduce noise in a lens barrel that is zoom-driven by a cam mechanism.

  In order to achieve the above object, the lens barrel according to claim 1 includes a cam ring having a cam groove formed on a peripheral surface thereof, and a holding portion for holding a spherical engagement member that engages with the cam groove. And a lens holding frame having a lens therein, and a cam mechanism that moves the lens ring along the cam groove in the optical axis direction of the photographing optical system by moving the cam ring. A lens barrel that can pass between the cam ring and the lens holding frame and reach the holding portion when the cam ring and the lens holding frame are in a predetermined positional relationship. And a built-in passage for an engaging member having a groove deeper than the cam groove.

  According to the present invention, in a lens barrel that is zoom-driven by a cam mechanism, it is possible to provide a lens barrel that can reduce the driving load during zoom driving and that can stabilize zooming and reduce noise.

It is a longitudinal cross-sectional view which shows the state which has the lens-barrel concerning embodiment of this invention in a retracted position (SINK position). It is a longitudinal cross-sectional view which shows the state in which the lens barrel concerning embodiment of this invention exists in the position (WIDE position) extended to the wide-angle end. It is a perspective view which takes out and shows the 1st group lens barrel in the lens barrel concerning embodiment of this invention. It is sectional drawing which expands and shows the principal part of the cam mechanism using the ball follower used for the lens-barrel concerning embodiment of this invention. FIG. 4 is a development explanatory view showing a cam groove portion provided on an inner peripheral surface of a movable cam ring in a lens barrel according to an embodiment of the present invention. It is sectional drawing which expands and shows the principal part which made the ball follower holding | maintenance part of the cam mechanism used for the lens barrel concerning embodiment of this invention the mortar shape. It is a perspective view which shows the 1st group lens barrel before incorporating in a movable cam ring in the lens barrel concerning embodiment of this invention. It is a perspective view of a lens barrel showing a state of a ball follower built-in phase in a lens barrel according to an embodiment of the present invention. It is sectional drawing by the BB line of FIG. 1 is an overall perspective view showing a state in which a lens barrel is in a retracted position with a power supply turned off in a photographing apparatus as an optical apparatus including a lens barrel according to an embodiment of the present invention. 1 is an overall perspective view showing a state in which a lens barrel is extended when a power is turned on in a photographing apparatus as an optical apparatus including a lens barrel according to an embodiment of the present invention. It is a block diagram which shows the principal part of the structure of the control system of the digital camera which is an imaging device as an optical apparatus provided with the lens barrel concerning embodiment of this invention. It is principal part sectional drawing which expands and illustrates the principal part of the cam mechanism used for the lens-barrel as a comparative example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  As shown in FIGS. 10 and 11, the digital camera 100 including the lens barrel according to the present embodiment is a camera having a zoom mechanism that can change the photographing magnification.

  A finder 34 for determining the composition of the subject, an auxiliary light 33 for assisting a light source when performing photometric distance measurement, a strobe 35, and a photographing lens barrel 36 are configured on the front of the digital camera 100. A release button 30, a power switch button 32, and a zoom switch 31 are disposed on the top surface of the digital camera 100.

  Although not shown, a card battery cover having a tripod mounting portion, a memory card drive, and a battery insertion portion is disposed on the bottom surface of the digital camera 100. Further, on the back of the digital camera 100, operation buttons for selecting an operation mode of the digital camera, for example, a shooting mode, a playback mode, a moving image shooting mode, and the like are arranged. At the same time, a display made of LCD and a viewfinder eyepiece are disposed on the back of the digital camera 100. This display is image display means, and displays image data stored in a memory and image data read from a memory card on a screen. When a mode is selected, a plurality of shooting data can be reduced and displayed on the screen.

  As shown in FIG. 12, the control unit in the control system of the digital camera 100 includes a CPU 63, a ROM 62, and a RAM 64. Various components such as a release button 30, a plurality of operation button groups 39, a display 38, a memory 57, and a memory card drive 59 are connected to the CPU 63, ROM 62, and RAM 64 through a bus 61.

  Furthermore, a zoom motor driving unit 47, a focus motor driving unit 49, a shutter driving unit 51, an imaging device 4 such as a CCD or a CMOS, and a strobe 35 are connected to a driving circuit 60 connected to a control system via a bus 61. Yes.

  The control system transmits a control signal to control each drive unit of the drive circuit 60. The ROM 62 of the control unit stores a program for controlling the above-described functional components. The RAM 64 stores data necessary for each control program.

  In the digital camera 100 configured as described above, when the user turns the power supply from OFF to ON by operating the power switch button 32, the CPU 63 reads a necessary control program from the ROM 62 and starts an initial operation. That is, the CPU 63 moves the photographic lens barrel to a predetermined shootable area, activates the photographic function, and sets the photographic standby state.

  In the state of the digital camera 100, the user can press the release button 30 to take a picture. When the user presses the release button 30, the CPU 63 of the control unit detects the brightness of the subject by the imaging device 4, and determines whether the aperture value, shutter speed, and flash 35 are to be emitted based on the photometric value. . In addition, the digital camera 100 is configured so that the user can select in advance by using the operation button 40 whether the strobe 35 is forced to emit light or not.

  Next, the control unit measures the distance, measures the distance to the subject, and moves the focus unit 48 to a predetermined focus position by the focus motor driving unit 49. Next, the control unit performs opening / closing control of the shutter unit 50 and captures a desired image into the imaging device 4.

  The imaging device 4 accumulates electric charges according to the amount of incident light based on the exposure control value, and the electric charges become an image signal and are output to the analog signal processing means 54.

  The analog signal processing means 54 performs analog processing on the captured image data and outputs it to the A / D converter 55. The A / D converter 55 converts the captured analog data into digital data. The A / D converter 55 outputs the digital data to the digital signal processing means 56. The digital signal processing means 56 processes digital data. Finally, the digital data is stored in the memory 57.

  The data stored in the memory 57 is subjected to compression processing such as JPEG or TIFF by the compression / expansion means 58 by the operation of the operation button 41, and is output to and stored in a memory card.

  In the case of a digital camera not having the memory 57, the digital data processed by the digital signal processing means 56 is output to the compression / expansion means 58 and stored in the memory card drive 59.

  The image data stored in the memory 57 or the image data stored in the memory card drive 59 is configured to be displayed on the display 38 via the bus 61 after being expanded by the compression / expansion means 58. .

  The data displayed on the display 38 is viewed by the user. When the user determines that the image of the data displayed on the display 38 is unnecessary, the user can delete the data by operating the operation button 42.

  In the digital camera 100, when the zoom switch 31 is operated by the user, the control unit controls the zoom motor driving means 47 via the drive circuit 60, so that the photographing lens barrel 36 is moved in the optical axis direction of the lens. Move to. The digital camera 100 also has a so-called digital zoom function for enlarging and reducing the stored image displayed on the display 38 by operating the zoom switch 31.

  Next, the configuration of the taking lens barrel 36 provided in the digital camera 100 according to the present embodiment will be described.

  1 and 2, reference numerals 1 and 2 denote a first group lens having a zooming action, a second group lens, 3 a third group lens for controlling focus and image plane correction, and 4 a CCD as an imaging device. Further, in FIGS. 1 and 2, reference numerals 11, 12, and 13 denote a first group barrel, a second group barrel, and a third group barrel that hold each group lens therein. The first group barrel 11 and the second group barrel 12 are held by a movable cam ring 21 having a cam groove on the inner circumferential surface.

  In FIGS. 1 and 2, reference numeral 22 denotes a fixed cylinder, and a movable cam ring 21 is movably held by a cam groove provided on an inner peripheral surface. In FIG. 1 and FIG. 2, reference numeral 23 denotes a CCD holder that holds the CCD 4, and is fixed to the fixed cylinder 22. 1 and 2, reference numeral 24 denotes a drive ring for rotating the movable cam ring, and reference numeral 25 denotes a rectilinear guide ring for suppressing the rotation of the first group barrel 11 and the second group barrel 12 to move straight. . 1 and 2, reference numeral 26 denotes a cover cylinder, which is fixed to the CCD holder 23 and has a function of restricting movement of the drive ring 24 in the optical axis direction.

  Next, the photographing lens barrel 36 configured as described above will be described in accordance with the operation.

  In the digital camera 100, a gear gear for transmitting the rotational force of a zoom motor (not shown) serving as a drive source meshes with an outer peripheral gear 24a provided on the drive ring 24 so that the drive ring 24 is rotated. It is configured.

  The drive ring 24 has a front end portion in contact with the flange portion 26a of the cover cylinder 26 and a rear end portion in contact with a flange portion 22c provided at the rear end portion of the fixed cylinder 22, thereby It is arranged so that movement is restricted.

  Three rectilinear guide grooves (not shown) having a uniform width in the optical axis direction are provided on the inner peripheral side surface of the drive ring 24.

  Further, on the outer periphery of the movable cam ring 21, three followers that are engaged with the three inner surface cam grooves 22 a of the fixed cylinder 22 are held. The moving cam ring 21 moves along the cam groove 22a of the fixed cylinder 22 according to the rotation.

  Furthermore, a drive pin 21a is planted substantially behind the follower. The drive pin 21 a passes through three guide grooves 22 b provided in the side surface of the fixed cylinder 22 and penetrates in the thickness direction, and is slidably fitted to the straight guide groove of the drive ring 24.

  In the lens barrel configured as described above, when the drive ring 24 is rotated, the rotation is transmitted to the movable cam ring 21 through the drive pin 21 a, and the movable cam ring 21 rotates along the cam groove 22 a of the fixed cylinder 22. While moving in the optical axis direction.

  Here, the linear guide ring 25 is restricted from moving relative to the movable cam ring 21 in the optical axis direction. The rectilinear guide ring 25 is fitted in a rectilinear guide (not shown) provided on the inner peripheral side surface of the fixed cylinder 22 so as to be able to advance straight. Therefore, the rectilinear guide ring 25 is configured such that the movement of the rectilinear guide tube 25 in the rotational direction is restricted.

  In the lens barrel configured as described above, when the movable cam ring 21 rotates and moves along the cam groove 22a of the fixed cylinder 22, the rectilinear guide ring 25 follows the movement of the movable cam ring 21 in the optical axis direction. It moves only in the optical axis direction.

  The first group barrel 11 and the second group barrel 12 are held in the inner surface cam grooves 21b and 21c of the movable cam ring 21, respectively. Each of the first group barrel 11 and the second group barrel 12 is restrained from rotational movement by the straight guide ring 25. For this reason, when the movable cam ring 21 moves, each of the first group barrel 11 and the second group barrel 12 moves in the optical axis direction without rotating, so that a lens can be arranged according to a desired focal length. It becomes possible.

  A known lens barrier 11 a is attached to the first group barrel 11. The lens barrier 11a blocks the optical path of the photographing optical system when in the retracted state.

  The second group barrel 12 is equipped with a known shutter unit and camera shake correction mechanism. These shutter unit and camera shake correction mechanism move in the optical axis direction integrally with the second group barrel 12.

  Next, with reference to FIGS. 3, 4, and 5 regarding the ball follower portion provided in the first group lens barrel 11 as a cylinder having a lens inside, relating to the main part of the lens barrel of the present embodiment. Will be described in detail.

  In this lens barrel, instead of a follower pin, a spherical ball follower is used for engagement with a cam groove. Although the ball follower is also used for the follower 21a of the moving cam ring 21, the description thereof is omitted because it has the same function.

  The first group lens barrel 11 is configured to hold three ball followers 14 arranged at positions equal to 120 degrees on the circumference. Each ball follower 14 is engaged with an inner surface cam groove 21 b of the corresponding moving cam ring 21.

  The first group lens barrel 11 is provided with backlash absorbing means for the first group lens barrel 11. This backlash absorbing means urges one of the three ball followers 14 in the radial direction, and the urging force urges the ball follower 14 against the cam groove 21b of the movable cam ring 21 so that the first group lens barrel It is configured to absorb eleven play.

  For this reason, a plate spring storage portion 11b is provided corresponding to a predetermined ball follower 14, and a plate spring 15 is incorporated therein to constitute a structure for urging the ball follower 14 to be pressed against the cam groove 21b.

  Further, the ball follower 14 disposed in the first group lens barrel 11 is rotatably fitted and held in the ball follower holding portion 11c.

  In the first group barrel 11, when the movable cam ring 21 rotates during zoom driving, the ball follower 14 rolls into contact with the cam groove 21b and the ball follower holding portion 11c, and the first group barrel 11 follows the cam locus of the cam groove 21b. Along the optical axis.

  In the first group lens barrel 11 equipped with the ball follower 14, the driving load during zoom driving can be reduced by utilizing the rolling friction by the ball follower 14 for the contact between the follower and the cam groove in the cam mechanism.

  Further, the first group lens barrel 11 to which this ball follower 14 is attached has a structure in which the ball follower 14 is fitted and held in the ball follower holding portion 11c. For this reason, this lens barrel is provided with means for preventing the ball follower 14 from falling off the ball follower holding portion 11c or the cam groove 21b when an external force is applied due to a drop impact or the like.

  In order to constitute this drop-off suppressing means, a fixed pin 16 as a second engaging member is planted in the first group barrel 11 behind the ball follower 14. The fixed pin 16 is engaged in a cam groove 21d (second cam groove) provided in the movable cam ring 21.

  The cam groove 21d (second cam groove) is configured in the same locus as the cam groove 21b (first cam groove) (see FIG. 5). This is because both the ball follower 14 and the fixing pin 16 (second engaging member) are held by the first group barrel 11.

  The fixing pin 16 and the cam groove 21d constituting the drop-off suppressing means are for receiving an external force and are not used during normal use. Therefore, a certain gap is provided between the fixed pin 16 and the cam groove 21d so as to be in a non-contact state so as not to be a zoom driving resistance (see FIG. 4). Then, only when the lens barrel receives an external force, the fixing pin 16 comes into contact with the cam groove 21d and receives an external force such as a drop impact, thereby preventing the ball follower 14 from falling off.

  In the lens barrel configured as described above, a ball follower is used for the cam mechanism, and it is rotatably fitted and held, and rolling friction is used for the contact between the follower and the cam groove, so that friction during zoom driving is achieved. Can be reduced.

  At the same time, in this lens barrel, in addition to the cam mechanism using the ball follower, an external force such as a drop is received by another engagement structure that is a drop prevention means, so that the ball follower constituting the cam mechanism is prevented from falling off. Can be achieved.

  Further, according to the lens barrel configured as described above, since the cam mechanism using the ball follower is used, the driving load during zoom driving can be reduced and the zoom driving operation can be stabilized. At the same time, this lens barrel can reduce noise energy and reduce noise by reducing friction.

  Next, in the lens barrel according to the present embodiment, a configuration for reducing the total length of the movable cam ring 21 in the optical axis direction will be described with reference to FIGS. 4, 5, 6, and 13. .

  In the cam mechanism shown in the comparative example of FIG. 13 used for the lens barrel, the follower pin 202 engages with one cam groove 203a to advance and retract the lens holding frame 201 along the cam locus, and when an external force is applied. It also has a function to prevent falling out.

  On the other hand, the lens barrel according to the present embodiment requires a cam mechanism using the ball follower 14 and the cam groove 21b, a fixing pin 16 for preventing the drop and the cam groove 21d. For this reason, it is necessary to arrange two cam grooves 21b and 21d having the same locus on the moving cam ring 21. For this reason, for example, when configured using a ball follower having a large diameter, the entire length of the movable cam ring 21 in the optical axis direction is longer than that of the comparative example.

  The total length of the movable cam ring 21 is determined by the distance M in the optical axis direction between the cam grooves 21b and 21d. The distance M is a distance necessary so that the cam grooves 21b and 21d in FIG. 5 do not overlap in the region A that extends from SINK (collapse position) to WIDE (wide angle end). In order to further shorten the entire length of the movable cam ring 21 while maintaining this distance M, the cam groove width w1 of the cam groove 21b must be reduced.

  Here, the ball follower holding portion 11c needs to be fitted and held so as to be rotatable while regulating the position of the ball follower 14. Therefore, as shown in FIG. 4, the ball center of the ball follower 14 must be within the outer shape of the first group lens barrel 11 (indicated by L in FIG. 4). Further, in order to configure so that the ball follower 14 does not fall off the cam groove 21b during normal zoom driving, it is necessary to secure a minimum required amount d1. From such conditions, the cam groove width w1 is naturally determined as shown in FIG.

  Therefore, in the present embodiment, in order to reduce the cam groove width w1 of the cam groove 21b, a cam mechanism is configured using a ball follower 17 having a smaller diameter than the ball follower 14, as shown in FIG. In the cam mechanism configured as shown in FIG. 6, the minimum required amount d2 of the cam groove 21b of the ball follower 17 is secured in the same manner as the amount d1 shown in FIG. Even with this configuration, in the cam mechanism having the configuration shown in FIG. 6, the cam groove width w2 can be made smaller than w1, and the entire length of the movable cam ring 21 can be shortened.

  However, in the cam mechanism having the configuration shown in FIG. 6, the ball center of the ball follower 17 cannot be accommodated within the outer shape of the first group barrel 11 by securing the amount of engagement d2. For this reason, in the cam mechanism having the configuration shown in FIG. 6, the mortar-shaped holding portion 11d is provided in the first group barrel 11, and the position of the ball follower 17 is restricted on the inclined surface in the mortar-shaped recess (conical trapezoidal recess). It is configured to be held rotatably.

  According to the cam mechanism having the configuration shown in FIG. 6, the ball follower holding portion is formed into a mortar (conical trapezoidal recess) shape, thereby reducing the ball follower diameter and reducing the cam groove width of the moving cam ring. The total ring length can be shortened.

  Next, in the lens barrel according to the present embodiment, means for improving the incorporation of the ball follower at the time of manufacture will be described with reference to FIGS. 5, 7, 8, and 9. FIG.

  In the present embodiment, the ball follower 17 (or 14) is configured to be rotatably held by the first group barrel 11.

  For example, if the assembly operation is performed with the ball follower 17 in a state before being incorporated into the movable cam ring 21 being simply placed on the first group barrel 11, the ball follower 17 falls due to its own weight. .

  For this reason, in this ball follower assembly manufacturing process, the ball follower 17 is dropped when the first group lens barrel 11 is in a vertically downward posture with three ball followers 17 fitted in the first group lens barrel 11. Support not to. In this state, the assembling process for incorporating the first group lens barrel 11 into the movable cam ring 21 while preventing the ball follower 17 from dropping from the first group lens barrel 11 is a difficult task. End up.

  Therefore, in the present embodiment, the configuration is such that the ball follower 17 can be assembled from the rear end of the movable cam ring 21 after the first group lens barrel 11 has been incorporated into the movable cam ring 21, and the work of assembling the ball follower is facilitated. I can do it.

  For this reason, as shown in FIG. 5, in the means for improving the incorporation of the ball follower at the time of manufacturing the lens barrel, the cam groove 21b is arranged at the rear end of the moving cam ring 21 in the phase of “ASSY first group”. Configure to open.

  In short, in the means for improving the ball follower integration when manufacturing the lens barrel, the movable cam ring 21 and the first group lens barrel 11 have a predetermined positional relationship as the ball follower installation position. At this predetermined positional relationship, the ball follower 14 is assembled by setting the ball follower 14 (17) at the assembly position.

  For this reason, the deep groove | channel for enabling the ball follower 14 to reach | attain in the holding part of the mortar-shaped holding part 11d of the 1st group barrel 11 which opposes a part of cam groove 21b from the entrance of the edge part of the movable cam ring 21 An engaging passage for the engaging member is provided. The assembly passage of the engaging member corresponds to the “ASSY 1 group” region shown in FIG. 9.

  Here, the cam groove 21b is configured by increasing the cam groove depth in the “ASSY first group” region, which is the phase in which the ball follower 17 is incorporated, with respect to the normal region from SINK to WIDE, TELE (telephoto end). To do. That is, as shown in FIG. 9, the cam groove 21b constitutes an assembly passage for the engaging member by making the cam groove depth D2 in the “ASSY 1 group” region deeper than the cam groove depth D1 in the normal region. To do. The cam groove depth D2 in the “ASSY first group” region is such that the ball follower 17 from the rear end of the movable cam ring 21 in the state shown in FIG. It is set to have enough depth to incorporate. In other words, the cam groove (engagement passage for the engagement member) in the “ASSY Group 1” region is formed to be slightly larger than the outer shape of the ball follower 17 that is a spherical engagement member, and the ball follower 17 easily passes therethrough. Make it possible.

  In this cam groove 21b, a locking projection 21e is projected from a connecting portion between the cam groove portion (the assembly passage of the engaging member) in the “ASSY first group” region and the cam groove portion in the normal region. The locking projection 21e enters from the entrance of the rear end of the movable cam ring 21, and the ball follower 17 that passes through the cam groove portion in the “ASSY 1 group” region passes over the locking projection 21e and has a mortar shape holding portion 11d. It is configured so that it can be incorporated into.

  At the same time, once the ball follower 17 has been incorporated into the holding portion of the mortar-shaped holding portion 11d, the locking projection 21e can be prevented from temporarily disengaging the ball follower 17 from the mortar-shaped holding portion 11d. Configure in shape.

  As shown in FIG. 9, the locking projection 21e faces the corner so as to face the slope in the holding portion of the mortar-shaped holding portion 11d (the slope in the mortar-shaped recess). Further, the locking protrusion 21e is configured such that the distance between the slope and the apex of the corner is slightly smaller than the diameter of the ball follower 17. The locking protrusion 21e is configured to exhibit a function as a stopper when the movable cam ring 21 is in the position where the ball follower 17 is assembled.

  The locking projection 21e is configured such that when the lens barrel is disassembled, the locking projection 21e can be moved over the ball follower 17 and detached from the mortar-shaped holding portion 11d.

  Next, the first group lens barrel 11 is mounted on the movable cam ring 21 provided with the cam groove portion for inserting the ball follower 17 in the “ASSY first group” region following the entrance of the rear end of the movable cam ring 21 as described above. The work process to be incorporated will be described.

  In this assembling process, first, the leaf spring 15 and the three fixing pins 16 are assembled into the first group barrel 11 (see FIG. 7). Since the leaf spring 15 and the fixing pin 16 are fixed to the first group barrel 11, they are not dropped from the first group barrel 11 during the assembly.

  Next, the three fixing pins 16 are aligned with the (fixing pins) of the phase “ASSY group 1” opened at the rear end of the moving cam ring 21 in FIG. 5. In this state, the first group lens barrel 11 is assembled to the movable cam ring 21 up to the built-in phase position C before the phase “SINK first group (fixed pin)”, and the ball follower 17 shown in FIG. It is assumed that it can be installed.

  The work of assembling the ball follower 17 is performed according to the phase of “ASSY Group 1” of the cam groove 21b (see FIG. 5).

  In the assembling work of the ball follower 17, the ball follower 17 is inserted in the direction of the arrow in FIG. 9 from the entrance opening the ball follower 17 at the rear end of the moving cam ring 21. In the assembling work of the ball follower 17, the ball follower 17 is assembled into the holding portion of the mortar-shaped holding portion 11d by getting over the locking projection 21e at the end of the “ASSY first group” region of the cam groove 21b. Complete the work.

  According to the lens barrel that is zoom-driven by the cam mechanism configured as described above, the operation of the zoom drive can be stabilized by reducing the driving load by using the ball follower. At the same time, in this lens barrel, noise energy can be reduced and noise reduction can be achieved by reducing friction. In addition, in this lens barrel, since the ball follower is held in a mortar shape that is a conical recess, the overall length of the cam barrel can be shortened.

  Further, in this lens barrel, a groove portion related to the ball follower incorporation phase is provided following the regular region of the cam groove and reaching the entrance opening at the rear end of the movable cam ring 21. That is, the groove portion related to the ball follower built-in phase is provided outside the normal area of the cam groove. Further, the groove portion related to the ball follower incorporation phase of the cam groove is formed relatively deep so that the ball follower can easily pass therethrough. Then, the ball follower 17 can be incorporated into the holding portion of the mortar-shaped holding portion 11d from the entrance opening at the rear end of the moving cam ring 21 through the portion related to the ball follower incorporation phase. Therefore, in this lens barrel, the work of assembling the first group barrel to the movable cam ring can be facilitated.

  The present invention is not limited to the above-described embodiment, and various modifications and changes can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 1st group lens 2 2nd group lens 3 3rd group lens 4 Imaging device 11 1st group barrel 12 2nd group barrel 13 3rd group barrel 14 Ball follower 15 Leaf spring 16 Fixing pin 17 Ball follower 21 Moving cam ring 22 Fixed cylinder 23 CCD holder 24 Drive ring 25 Straight guide ring 26 Cover tube 30 Release button 31 Zoom switch 32 Power switch button 33 Auxiliary light 34 Viewfinder 35 Strobe 36 Shooting lens barrel 37 Viewfinder eyepiece 38 Display 39 to 44 Operation button 45 Tripod mounting Unit 46 card battery cover 47 zoom motor drive means 48 focus means 49 focus motor drive means 50 shutter means 51 shutter drive means 52 aperture means 53 aperture drive means 54 analog signal means 55 A / D converter 56 digital signal processing means 57 Memory 58 Compression / decompression means 59 Memory card drive 60 Drive circuit 61 Bus 62 ROM
63 CPU
64 RAM

Claims (6)

A cam ring having a cam groove formed on the peripheral surface;
A holding portion for holding a spherical engagement member that engages with the cam groove, and a lens holding frame having a lens inside;
A lens barrel having a cam mechanism for moving the lens holding frame forward and backward in the optical axis direction of the photographing optical system along the cam groove by moving the cam ring;
When the cam ring and the lens holding frame are in a predetermined positional relationship, a groove deeper than the cam groove is formed so as to pass between the cam ring and the lens holding frame and reach the holding part. A lens barrel comprising a built-in passage for an engaging member.   The lens barrel according to claim 1, wherein a locking projection for preventing the engaging member from falling out of the holding portion is provided in the cam groove portion.   The lens barrel according to claim 1, wherein the holding portion of the lens holding frame is formed so as to rotatably hold the spherical engagement member in a mortar-shaped recess.   In addition to the feeding cam mechanism, there is a drop prevention means for preventing the spherical engagement member from dropping when an external force is applied between the lens holding frame and the cam ring. The lens barrel according to any one of claims 1 to 3.   The lens barrel according to any one of claims 1 to 4, wherein the engagement passage of the engaging member is provided outside a normal region of the cam groove.   6. The lens barrel according to claim 1, wherein the normal region is a region from a retracted position to a wide-angle end and a telephoto end in the lens barrel.