JP5430258B2 - Lens barrel - Google Patents

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 that can be advanced and retracted in the optical axis direction by rotation of the cam ring, and the cam ring is located at a position outside the telephoto end region from the retracted position in the cam groove. the insertable in a an insertion hole provided through transmural, the locking projection and you elastically deformable collision set inside the insertion hole, the engaging member of the spherical, the lens holding frame is the When the holding portion and the insertion hole are incorporated in the cam ring in a state of being opposed to each other, the insertion portion is inserted from the outside of the cam ring through the insertion hole, and gets over the deformation projection while deforming the locking projection. incorporated and wherein the Rukoto.

According to the present invention, the engaging member spherical is used as follower of the cam mechanism, as compared with the case follower is follower pin to reduce the driving load at the time of zoom driving of the lens barrel, a zoom driving Can be stabilized . Further, since the follower can reduce the friction caused by the cam mechanism as compared with the case of the follower pin to reduce the noise energy in occurs when the zoom driving can be noise reduction. Further, since this spherical engaging member is inserted from the outside of the cam ring through an insertion hole provided in the cam ring and is incorporated into the holding portion provided in the lens holding frame, the spherical engagement to the cam mechanism is achieved. Assembling work of members can be easily performed. Further, in this assembling operation, the spherical engaging member is incorporated into the holding portion by overcoming the engaging protrusion that protrudes elastically deformable inside the insertion hole, so that the spherical engaging member is It can be prevented from falling outside through the insertion hole.

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 which exists in the position (WIDE position) where the lens-barrel concerning embodiment of this invention extended. 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. It is sectional drawing by CC 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. 11 and 12, 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. 13, 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 movably in the optical axis direction. 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 periphery.

  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 the inner periphery. 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 21 a that fit into 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.

  Further, a drive pin 21b is planted substantially behind the follower 21a. The drive pin 21 b 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 driving ring 24 is rotated, the rotation is transmitted to the moving cam ring 21 through the driving pin 21 b, and the moving 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 movement of the rectilinear guide ring 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 cam grooves 21c and 21d on the inner surface 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, the ball follower portion provided in the first group barrel 11 related to the main part of the lens barrel of the present embodiment will be described in detail with reference to FIGS. 3, 4 and 5.

  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 a cam groove 21 c on the inner surface of the corresponding movable cam ring 21.

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

  For this reason, a plate spring housing 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 into the cam groove.

  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 21c and the ball follower holding portion 11c, and the first group barrel 11 follows the cam locus of the cam groove 21c. 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 21c when an external force is applied due to a drop impact or the like.

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

  The cam groove 21e, which is the second cam groove, has the same locus as the cam groove 21c, which is the first cam groove (see FIG. 5). This is because the ball follower 14 and the fixing pin 16 are both held by the first group barrel 11.

  Further, the fixing pin 16 as the second engaging member constituting the drop-off suppressing means and the cam groove 21e as the second cam groove are for receiving an external force and are not used during normal use. Therefore, a certain gap is provided between the fixing pin 16 as the second engaging member and the cam groove 21e as the second cam groove so as not to be in a contact state, and does not become a zoom driving resistance. (See FIG. 4). Then, only when the lens barrel receives an external force, the fixing pin 16 that is the second engaging member comes into contact with the cam groove 21e that is the second cam groove and receives an external force such as a drop impact, whereby the ball follower 14 is prevented 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, a configuration for reducing the overall length of the movable cam ring 21 in the optical axis direction in the lens barrel according to the present embodiment will be described with reference to FIGS. 4, 5, 6, and 14. .

  In the cam mechanism shown in the comparative example of FIG. 14 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 configured to be able to advance and retreat using the ball follower 14 and the cam groove 21c that is the first cam groove. At the same time, this lens barrel requires a fixing pin 16 for preventing the drop and a cam groove 21e as a second cam groove. For this reason, the moving cam ring 21 needs to be provided with two cam grooves 21c having the same locus, that is, a cam groove 21c and second cam groove 21e. For this reason, when it comprises using the ball follower 17 which is a spherical engaging member with a large diameter as shown in FIG. 6, compared with the comparative example, the full length of the moving cam ring 21 in the optical axis direction becomes long.

  The total length of the movable cam ring 21 is determined by the distance M in the optical axis direction between the cam grooves 21c and 21e. The distance M is a distance necessary so that the cam grooves 21c 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 21c 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 out of the cam groove 21c 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 21c, the cam mechanism is configured using a ball follower 17 that is a spherical engagement member having a smaller diameter than the ball follower 14, as shown in FIG. Configure. In the cam mechanism configured as shown in FIG. 6, the minimum required amount d2 of the cam groove 21c 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, it is impossible to fit the spherical center of the ball follower 17, which is a spherical engagement member, 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 first group barrel 11 is provided with a mortar-shaped holding portion 11d to restrict the position of the ball follower 17 on the mortar-shaped (conical-conical concave) slope and to be rotatable. Configure to hold.

  According to the cam mechanism having the configuration shown in FIG. 6, the ball follower holding portion is formed in a mortar shape (conical truncated conical recess), 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 FIG. 5, FIG. 7, FIG. 8, FIG. To do.

  In the present embodiment, the ball follower 17 (or 14), which is a spherical engagement member, is structured 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 ball follower is configured to be incorporated from the outside of the movable cam ring 21 after the first group lens barrel 11 is incorporated into the movable cam ring 21, so that this ball follower can be easily assembled. I have to.

  For this reason, as shown in FIG. 5, in the means for improving the ball follower integration when manufacturing the lens barrel, as shown in FIG. 5, the ball follower 17 which is a spherical engagement member is engaged with one end of the cam groove 21c. A through hole 21f which is an insertion hole is drilled.

  The through hole 21f as an insertion hole is disposed at a position corresponding to the phase of “ASSY ball follower” in the cam groove 21c with which the ball follower 17 is engaged. The through hole 21f, which is an insertion hole, has a circular opening that is slightly larger than the diameter of the ball follower 17 that is a spherical engagement member that penetrates the inside and outside of the movable cam ring 21, and is formed so that the ball follower 17 can be inserted. That is, the through hole 21f is formed in a hole shape through which the ball follower 17 can be inserted.

  Further, a locking portion (locking protrusion) which is a protrusion having a triangular cross section is formed on a part of the inner peripheral surface of the through hole 21f which is an insertion hole drilled in the movable cam ring 21 on the first group lens barrel 11 side. 21 g is projected.

  When the ball follower 17 is pushed into the through-hole 21f, the locking portion 21g, which is the locking protrusion, moves over the locking portion 21g by slightly elastically deforming the moving cam ring 21, and moves into the bowl-shaped holding portion 11d. Projected to fit in.

  The locking portion 21g, which is the locking protrusion, functions as a stopper that temporarily stops and stops the ball follower 17 that has been received in the bowl-shaped holding portion 11d so as not to fall off through the through hole 21f. It is configured to have a shape.

  Next, an operation process for incorporating the first group barrel 11 into the movable cam ring 21 in which the through hole 21f as described above is formed will be described.

  In this assembling operation step, first, the leaf spring 15 and the fixing pins 16 that are the three second engaging members are assembled in 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 first group barrel 11 is assembled into the movable cam ring 21. This assembling work is performed in a state where the first group barrel 11 is set to the phase of “ASSY first group” as shown in FIG.

  For this reason, in this assembling work, the fixing pin 16 which is the second engaging member press-fitted and fixed to the first group barrel 11 is engaged with the moving cam ring 21 and the cam groove 21e. In this assembling work, the phase of the “ASSY ball follower” is sequentially passed from SINK through WIDE (wide angle end) and TELE (telephoto end) while the fixing pin 16 is guided by the cam groove 21e. It moves until it becomes (refer FIG. 8).

  Next, in the state of FIG. 8 in which the first group lens barrel 11 is incorporated in the moving cam ring 21 with the phase of “ASSY ball follower”, the ball follower 17 is moved from the outside of the moving cam ring 21 to the bowl-shaped holding portion through the through hole 21f. Drop into 11d. As a result, the ball follower 17 is inserted into the through hole 21 f and incorporated into the first group barrel 11.

  When the ball follower 17 is inserted into the through hole 21f and incorporated, the ball follower 17 slightly deforms the moving cam ring 21 and climbs over the locking portion 21g which is a locking projection into the bowl-shaped holding portion 11d. Set. Note that once the ball follower 17 is incorporated into the bowl-shaped holding portion 11d, the ball follower 17 is prevented from coming off by the locking portion 21g which is a locking protrusion. For this reason, the ball follower 17 does not fall out of the concave portion of the mortar-shaped holding portion 11d which is a truncated cone-shaped concave portion through the through hole 21f. Therefore, it becomes possible to easily incorporate the ball followers 17 arranged equally at 120 degrees in the state of FIG.

  Next, after incorporating the ball follower 17 into the mortar-shaped holding portion 11d through the through hole 21f, the first group barrel 11 is moved along the cam groove 21c in the phase “TELE (telephoto end)” direction. Here, as shown in FIG. 10, a guide portion 21h is formed at the communicating portion of the through hole 21f and the cam groove 21c. For this reason, when the first group barrel 11 is moved, the ball follower 17 is smoothly engaged with the cam groove 21c without being caught.

  As shown in FIG. 5, the range from the phase “SINK (collapse position)” to “TELE (telephoto end)” is the normal region of the lens barrel. On the other hand, the phase “ASSY ball follower” is outside the normal area where it hits one end of the cam groove 21c. For this reason, even if the through hole 21f is provided at the position of one end portion of the cam groove 21c, in this lens barrel, the through hole 21f does not hinder the zoom operation and the focusing operation.

  Further, in this lens barrel, after the ball follower 17 is assembled at the tip of the movable cam ring 21, a cam ring cap 27 is installed to hide the through hole 21f from the outside (FIG. 1). FIG. 2).

  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 truncated cone-shaped recess, the entire length of the cam barrel can be shortened.

  Further, in this lens barrel, since the through hole for incorporating the ball follower is provided outside the regular area of the cam groove, 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 cylinder 27 Cam ring cap 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 39-44 Operation Button 45 Tripod mount 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 / expansion means 59 Memory card drive 60 Drive circuit 61 Bus 62 ROM
63 CPU
64 RAM

Claims (4)

A cam ring having a cam groove formed on the peripheral surface;
A holding portion for holding a spherical engaging member that engages with the cam groove, and a lens holding frame that can advance and retract in the optical axis direction by rotation of the cam ring,
The cam ring includes an insertion hole formed through transmural an engagement member of said spherical to be inserted in a region outside of the telephoto end from the collapsed position in the cam groove, an elastically deformable to the inside of the insertion hole has a locking projection and you butt set,
The spherical engagement member is inserted from the outside of the cam ring through the insertion hole when the lens holding frame is incorporated in the cam ring with the holding portion and the insertion hole facing each other. a lens barrel, wherein Rukoto incorporated within the holding portion rides over while deforming the locking projection.   A guide portion that is an inclined surface that guides the spherical engaging member held by the holding portion of the lens holding frame into the cam groove is provided at a portion facing the insertion hole of the cam groove. The lens barrel according to claim 1.   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. Between the lens holding frame and the cam ring, in addition to the feeding cam mechanism, a drop-off suppressing means is provided that suppresses dropping of the spherical engagement member when an external force such as a drop impact is applied. And
The drop-off suppressing means is
A second cam groove formed in the cam ring;
A second engagement member provided on the lens holding frame so as to move in a non-contact state during normal use in the second cam groove;
The lens barrel according to any one of claims 1 to 3, wherein the lens barrel is provided.