JP4352494B2 - Lens barrel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lens barrel mounted on a camera or the like, and more particularly, to a technique that realizes quick and reliable switching between an autofocus mode and a manual focus mode.
[0002]
[Prior art]
Various types of lens barrels such as a wide-angle lens and a telephoto lens are mounted on the camera, including a single focus lens and a zoom lens. The lens barrel has a plurality of lens groups including one or a plurality of optical lenses, and focusing is performed by appropriately changing the relative distance between the lens groups. In recent years, even relatively low-price cameras have an autofocus mode in which the camera itself performs focusing in addition to the manual focus mode in which the photographer rotates the manual focus ring on the outer peripheral surface of the lens barrel. The mainstream is the mainstream. In this type of camera, a focusing drive control mechanism including a microcomputer, a CCD sensor, an electric motor, and the like is incorporated in the camera body. When the distance to the subject is detected, the electric motor is installed in the lens barrel. The focusing lens group is driven forward or backward.
[0003]
Normally, in a lens barrel for an autofocus camera, as described in Japanese Utility Model Laid-Open No. 3-26108, by operating a mode change switch provided on the side surface of the barrel or the like, autofocus and manual focus can be switched. Mode switching is possible. The mode changeover switch activates or stops the focusing drive control mechanism on the camera side, and activates a clutch that switches the driving source of the focusing lens group between the focusing drive control mechanism and the manual focus ring. That is, when the photographer switches the mode switch in the auto focus mode, the power supply to the focusing drive control mechanism is cut off, and at the same time, the interlocking ring connected to the focusing lens group holding cylinder is connected by the clutch. The focus drive control mechanism is switched to the manual focus ring, and the rotation of the manual focus ring is transmitted to the interlocking ring.
[0004]
[Problems to be solved by the invention]
In the lens barrel described in the above publication, since the mode change switch is a rotary switch (mode change ring) that is externally fitted to the lens barrel, there is a large problem in operability during photographing.
[0005]
For example, when photographing in the manual focus mode, it is common for the photographer to hold the camera body with the right hand and hold and rotate the manual focus ring of the lens barrel with the left hand. Therefore, the photographer must change the left hand from the manual focus ring to the mode switching ring and perform the rotation operation of the mode switching ring when switching from the manual focus mode to the auto focus mode. On the other hand, when switching from the auto focus mode to the manual focus mode, the left hand must be moved from the camera body or lens barrel to the mode switching ring, and then the manual focus ring must be held again with the left hand. . Normally, the photographer switches the mode while keeping the subject in the viewfinder, but these operations are frustrating, so it is difficult to obtain speediness and certainty, and this may cause a missed photo opportunity. In some cases, the camera is slightly shaken and the subject in the viewfinder is lost.
[0006]
Further, in the lens barrel described in the above publication, the rotation speed of the interlocking ring is ½ of the rotation speed of the manual focus ring due to the principle of the planetary gear mechanism. In general, the reduction ratio of the focusing drive control mechanism, the lead angle of the focusing cam formed on the focusing lens group holding cylinder, the drive time required for scanning from the ∞ position to the closest position, etc., are the characteristics of the drive motor in the camera body. And the load torque capacity for focusing of the lens barrel is naturally determined, and the rotation angle from the ∞ position to the closest position of the manual focus ring is similarly determined. However, this rotation angle only needs to be suitable for the manual focusing operation of the photographer, but if it is too large or too small, the moving speed of the subject image plane in the viewfinder with respect to the operation amount of the manual focus ring is out of the allowable range. There is a problem that the focusing operation becomes very difficult.
[0007]
The present invention has been made in view of the above circumstances, and provides a lens barrel that realizes quick and reliable switching between an autofocus mode and a manual focus mode and an improvement in operability during manual focusing. For the purpose.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, in the invention of claim 1, an autofocus mode in which the focusing optical system is driven by the focusing control device, and a manual focus mode in which the photographer drives the focusing optical system are provided. A switchable lens barrel, an operation unit for performing an operation for driving in the manual focus mode, and the focusing optical system in any of the auto focus mode and the manual focus mode The focusing optical system driving unit that drives the focusing optical system in the optical axis direction by rotating about the optical axis of the focusing optical system, and the driving amount by the focusing control device of the focusing optical system driving unit A stepped idler roller including a first annular portion that converts to drive, and a second annular portion that converts an operation amount of the operation portion to drive of the focusing optical system drive portion, The diameter of the first annular portion is different from that of the second annular portion, and the operation portion is in contact with the second annular portion of the stepped idler roller in the manual focus mode, and the autofocus. In this mode, a motor that can move between positions that do not come into contact with the stepped idle roller is proposed.
According to a second aspect of the present invention, in the lens barrel according to the first aspect of the present invention, the lens barrel includes a fixed cylinder that holds the focusing optical system driving unit on the inner side, and the focusing optical system driving unit is in contact with the fixed cylinder. The focusing optical system is relatively moved, and the fixed cylinder contacts the first annular portion of the stepped idler roller in the autofocus mode, and the stepped idler roller in the manual focus mode. Suggest something that doesn't touch
According to a third aspect of the present invention, in the lens barrel according to the first or second aspect, the focusing control device can rotate around the optical axis of the focusing optical system in the autofocus mode. The gear ring is in contact with the stepped idler roller in any of the autofocus mode and the manual focus mode, and the focusing optical system drive unit is in the autofocus mode. Furthermore, it is proposed to drive the focusing optical system as the gear ring rotates.
According to a fourth aspect of the present invention, in the lens barrel according to the third aspect, in the manual focus mode, the rotation of the gear ring is stopped and the operation of the operation unit is transmitted to the stepped idler roller. A first wave washer is proposed.
According to a fifth aspect of the present invention, in the lens barrel according to any one of the first to fourth aspects, the stepped idler roller is provided integrally with the focusing optical system driving unit. Propose.
According to a sixth aspect of the present invention, in the lens barrel according to any one of the first to fifth aspects, the switching between the autofocus mode and the manual focus mode is performed by moving the operation unit to the focusing optical system. We propose what is done by operating in the direction of the optical axis.
According to a seventh aspect of the present invention, in the lens barrel according to any one of the first to sixth aspects, the first annular portion and the second annular portion are optical axes of the focusing optical system. We propose the one with the center of rotation in the direction orthogonal to.
According to an eighth aspect of the present invention, in the lens barrel according to any one of the first to seventh aspects, the focusing control device is provided in a camera to which the lens barrel is mounted. Propose.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a lens barrel according to an embodiment of the present invention.
In FIG. 1, a member denoted by reference numeral 1 is a cylindrical fixed cylinder attached to a camera (not shown), a rear fixed cylinder 5 having a plurality of bayonet lugs 3 formed at the rear end, It consists of an external fixed cylinder 7 that forms a part of the lens barrel outer shell, and an internal fixed cylinder 13 that holds the first lens group 9 and the fourth lens group 11. The fixed cylinder 1 is composed of a plurality of members fastened and integrated by screws or the like, but in this embodiment, it is treated as a single member for convenience of explanation. In addition, the code | symbol L in a figure has shown the optical axis of the lens-barrel.
[0012]
On the front end face side of the rear fixed cylinder 5, an internal gear ring 23 having a gear portion 21 formed on the internal peripheral surface in a form of sliding contact with the internal peripheral surface of the external fixed cylinder 7, and the internal gear ring 23 are provided. A first wave washer 25 that is a first biasing member that biases forward is disposed. The lens barrel side coupler 27 is rotatably supported on the rear fixed cylinder 5. The lens barrel side coupler 27 is formed with a coupling portion 29 that engages with a camera side coupler (not shown) at the rear end, and a pinion 31 that meshes with the gear 21 of the inscribed gear ring 23 at the front end. Accordingly, when the camera side coupler is driven to rotate by a focusing motor (not shown) in the camera, the rotation is transmitted to the inscribed gear ring 23 via the lens barrel side coupler 27, and the inscribed gear ring 23 moves along the optical axis L. Rotate in either forward or reverse direction as the center.
[0013]
The internal fixed cylinder 13 has a focusing optical system holding ring that holds the second lens group 33 and the third lens group 35 constituting the focusing optical system between the first lens group 9 and the fourth lens group 11. 37 is fitted. The focusing optical system holding ring 37 is supported by the internal fixed cylinder 13 so as to be rotatable about the optical axis L and movable back and forth, and a plurality of interlocking links penetrating through a lead groove 39 formed in the internal fixed cylinder 13. A pin 41 projects from the outer peripheral surface. Further, an interlocking ring 45 having a flange 43 formed at the rear end portion is rotatably fitted to the internal fixed cylinder 13, and is focused on a linear groove 47 formed at the front portion of the interlocking ring 45. The interlocking pin 41 of the optical system holding ring 37 is engaged. Therefore, when the interlocking ring 45 is driven to rotate, the rotation is transmitted to the interlocking pin 41 via the linear groove 47, and the interlocking pin 41 moves along the lead groove 39, so that the focusing optical system holding ring 37 is moved. Advances and retracts along the optical axis L.
[0014]
A plurality of stepped idle rollers 53 are rotatably supported on the flange 43 of the interlocking ring 45 via pivots 51 protruding from the outer peripheral surface thereof. The stepped idler roller 53 according to the present embodiment is obtained by externally fitting and fixing an elastic body such as rubber to a metal cylinder, and its rotation center (that is, the axis of the pivot 51) is orthogonal to the optical axis L. Yes. As shown in FIG. 2, the stepped idle roller 53 has a large diameter portion 53a having a diameter Db and a small diameter portion 53b having a diameter Db ′. In the state of FIG. While contacting the front end surface of the internal gear ring 23, the front portion of the large diameter portion 53 a is in contact with the rear end surface of the race ring 55 formed inside the front portion of the external fixed cylinder 7, and the first wave washer 25. The stepped idle roller 53 is pressed between the inscribed gear ring 23 and the raceway ring 55 by the urging force. Therefore, when the inscribed gear ring 23 is rotationally driven, the stepped idle roller 53 that contacts the inscribed gear ring 23 rolls along the rear end surface of the raceway ring 55, and the stepped idle roller 53 is moved to the flange 43. The supported interlocking ring 45 rotates at half the rotational speed of the inscribed gear ring 23. A distance scale 57 is formed on a part of the outer peripheral surface of the flange 43 of the interlocking ring 45, and the shooting distance is measured through a scale confirmation window 59 made of a transparent synthetic resin fitted in a part of the external fixing cylinder 7. (The rotational position of the interlocking ring 45) can be confirmed.
[0015]
In the case of the present embodiment, the detent mechanism 71 is incorporated between the tip of the manual focus ring 61 and the internal fixed cylinder 13. As shown in FIG. 3 (enlarged view of portion A in FIG. 1), the detent mechanism 71 includes front and rear first and second annular grooves carved in a predetermined angle range on the inner peripheral surface of the manual focus ring 61. 73, 75, a ball storage hole 77 formed in the outer periphery of the internal fixed cylinder 13, a detent ball 79 stored in the ball storage hole 77, and the detent ball 79 are urged toward the inner peripheral surface of the manual focus ring 61. And a coil spring 81. The manual focus ring 61 has two positions, a manual focus position and an autofocus position (that is, the state shown in FIG. 1), which will be described later, when the detent ball 79 enters the first and second annular grooves 73 and 75. Each is locked and held. The spring force of the coil spring 81 is such that the manual focus ring 61 can be held at the manual focus position even when the manual focus ring 61 is urged forward by the first and second wave washers 25 and 65. Is set.
[0016]
The operation of this embodiment will be described below.
When photographing in the autofocus mode, the photographer holds the camera body with the right hand and holds the manual focus ring 61 with the left hand. At this time, since the detent ball 79 enters the second annular groove 75 as shown in FIG. 3 due to the urging force of the coil spring 81, the manual focus ring 61 is securely held at the autofocus position and moved carelessly. There is nothing to do. When the photographer views the subject in the viewfinder, the microcomputer in the camera rotates the camera-side coupler by the focusing electric motor or gear mechanism in accordance with the distance information input from the CCD sensor or the like. This rotation is transmitted to the lens barrel side coupler 27 engaged with the camera side coupler, and is formed at the front end of the lens barrel side coupler 27 as shown in FIG. 4 (an enlarged perspective view of the B portion in FIG. 1). The pinion 31 rotates in either the forward or reverse rotation direction (right direction in FIG. 4).
[0017]
When the pinion 31 rotates in the right direction, the inscribed gear ring 23 meshed with the pinion 31 also rotates in the right direction in FIG. 4, and the inscribed gear ring 23 is urged forward by the wave washer 25. The stepped idle roller 53 in contact with the front end face of the contact gear ring 23 rotates in the left direction in FIG. In the autofocus mode, the stepped idler roller 53 has a large-diameter portion 53 a that is in contact with the raceway ring 55 of the external fixed cylinder 7. Roll to. At this time, since the stepped idle roller 53 has a rotation center in a direction orthogonal to the optical axis L, the inscribed gear ring 23 and the raceway ring 55 are smoothly brought into rolling contact with each other, causing durability and abnormal noise. There is almost no wear or slip on the rolling contact surface.
[0018]
When the stepped idler roller 53 rolls, the interlocking ring 45 also supports the stepped idler roller 53 via the pivot 51 fixed to the flange 43. Therefore, the inward gear ring 23 is moved to the right in FIG. Rotates at 1/2 the number of revolutions. When the interlocking ring 45 rotates, this rotation is transmitted to the interlocking pin 41 fixed to the focusing optical system holding ring 37 via a linear groove 47 formed in the interlocking ring 45. Since the interlocking pin 41 is also engaged with the lead groove 39 of the internal fixed cylinder 13, the interlocking pin 41 advances and retreats along the optical axis L due to the inclination of the lead groove 39. As a result, the focusing optical system holding ring 37 integral with the interlocking pin 41 also advances and retreats, and the second lens group 33 and the third lens group 35 held by the focusing optical system holding ring 37 move along the optical axis L. Auto focusing is realized.
[0019]
When the photographer switches from the autofocus mode to the manual focus mode while keeping the subject in the viewfinder, as shown in FIG. 5, the photographer pulls the manual focus ring 61 backward with a predetermined force. Then, as shown in FIG. 6 (enlarged view of C portion in FIG. 5), the detent ball 79 enters the second annular groove 73, so that the manual focus ring 61 remains in the manual focus position even if the photographer releases his / her hand. Retained. In this state, the roller driving ring 63 of the manual focus ring 61 has its rear end face overcomes the urging force of the first wave washer 25 and comes into contact with the small diameter portion 53b of the stepped idle roller 53, and then the second wave washer 65. The stepped idler roller 53 is pushed backward by overcoming the urging force. As a result, the stepped idle roller 53 moves backward by a predetermined amount together with the interlocking ring 45 and the inscribed gear ring 23, and a gap is formed between the large diameter portion 53 a of the stepped idle roller 53 and the raceway ring 55. The
[0020]
On the other hand, when the manual focus ring 61 is retracted, the brush 67 fixed to the roller drive ring 63 is retracted on the flexible printed circuit board 69 attached to the external fixed cylinder 7. As a result, a signal indicating the manual focus mode is output from the signal processing board on the lens barrel side to the microcomputer on the camera side, and the drive of the electric motor is stopped in the camera. In this state, since the first wave washer 25 is compressed in the optical axis L direction, a predetermined frictional force is generated between the rear surface of the inscribed gear ring 23 and the front surface of the first wave washer 25. In the case of the present embodiment, the friction between the spring constant of the first wave washer 25 and the internal gear ring 23 and the first wave washer 25 so that this frictional force is larger than the rotational torque required for the rotation of the interlocking ring 45. The coefficient is set.
[0021]
In this state, as shown in FIG. 7 (part D enlarged perspective view in FIG. 5), when the photographer rotates the manual focus ring 61 in the right direction in FIG. The stepped idler roller 53 in contact also rotates rightward in FIG. In the manual focus mode, the stepped idler roller 53 has the inscribed gear ring because the inscribed gear ring 23 with which the large-diameter portion 53a is in pressure contact is stationary due to the frictional force with the first wave washer 25 described above. It rolls along the front end face of 23 in the right direction in FIG.
[0022]
When the stepped idle roller 53 rolls, the interlocking ring 45 that supports the stepped idle roller 53 also rotates in the right direction in FIG. In FIG. 8, the diameter of the contact portion of the inscribed gear ring 23 with the large-diameter portion 53a of the stepped idle roller 53 is Da, and the roller drive ring 63 is in contact with the small-diameter portion 53b of the stepped idle roller 53. If the diameter of the part is Dc, the diameter of the large-diameter portion 53a is Db and the diameter of the small-diameter portion 53b is Db ′. Therefore, according to the principle of the planetary gear mechanism, the rotation of the interlocking ring 45 per one rotation of the roller drive ring 63 The number N is Db · Dc / (Da · Db ′ + Db · Dc). Therefore, by rotating the outer diameter Db of the large diameter portion 53a and the outer diameter Db ′ of the small diameter portion 53b as appropriate, the rotation amount of the roller driving ring 63 (that is, the operation amount of the manual focus ring 61) is increased. It is possible to arbitrarily set the amount of rotation of the interlocking ring 45 with respect to (ie, the amount of advancement / retraction of the focusing optical system holding ring 37).
[0023]
As described above, in the lens barrel of the present embodiment, since it is possible to quickly switch modes while holding the manual focus ring 61, the operability is dramatically improved as compared with the conventional apparatus. When the mode is switched, it is less likely that the subject captured in the finder is lost. Further, since the manual focus ring 61 is locked and held at the autofocus position and the manual focus position by the detent mechanism 71, the operability is very good. Further, since the ratio between the amount of operation of the manual focus ring 61 by the photographer and the amount of rotation of the interlocking ring 45 can be set freely, optimum focusing operability can be obtained even in lens barrels of various specifications. Become.
[0024]
Although description of specific embodiment is finished above, the aspect of the present invention is not limited to this embodiment. For example, in the above embodiment, the manual focus ring is drawn backward when switching from the autofocus mode to the manual focus mode, but it may be pushed forward. In the above embodiment, the detent mechanism includes an annular groove and a detent ball. However, various structures such as those using a detent pin or a leaf spring can be used. In the above embodiment, the large-diameter portion of the stepped idle roller is brought into rolling contact with the raceway ring and the small-diameter portion is brought into rolling contact with the roller driving ring. However, this relationship may be reversed. In the above embodiment, the present invention is applied to a four-group lens barrel. However, the present invention may be applied to other types of lens barrels. Furthermore, the specific configuration and the like of the focus mechanism and the like are not limited to the examples in the above embodiment, and can be appropriately changed depending on the design convenience.
[0025]
【The invention's effect】
According to one aspect of the present invention , an autofocus mode in which the focusing control device drives and controls the focusing optical system via the rotation driving device and a manual focus mode in which the photographer drives the focusing optical system are selected. A lens barrel, which includes an interlocking ring and a focusing optical system holding member connected to the interlocking ring via a cam mechanism, and holds the focusing optical system in response to rotational input to the interlocking ring. A focusing optical system moving device that moves a member along the optical axis with respect to the fixed cylinder, an autofocus position for selecting the autofocus mode, and a manual focus position for selecting the manual focus mode with respect to the fixed cylinder A manual focus ring that can be manually rotated when switched to the manual focus position; When the manual focus ring is switched to the autofocus position, the rotational force of the rotary drive device is transmitted to the interlocking ring, while when the manual focus ring is switched to the manual focus position, the rotational force of the manual focus ring is transmitted. And a detent mechanism for holding the manual focus ring at the autofocus position or the manual focus position, respectively, so that the photographer can hold the manual focus ring forward while holding the manual focus ring. By moving backward, the mode can be switched quickly and easily, and the chance of missing a photo opportunity or losing sight of the subject in the viewfinder is reduced. Good operability is obtained to be held at the positions and manual focus position.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an autofocus mode of a lens barrel according to the present invention.
FIG. 2 is a perspective view showing a stepped idle roller.
FIG. 3 is an enlarged perspective view of a part A in FIG.
4 is an enlarged perspective view of a portion B in FIG. 1. FIG.
FIG. 5 is a longitudinal sectional view showing a lens barrel according to the present invention in a manual focus mode.
It is a longitudinal cross-sectional view which shows the principal part of the lens barrel which concerns on one Embodiment of this invention.
6 is an enlarged perspective view of a C part in FIG. 5. FIG.
7 is an enlarged perspective view of a D part in FIG. 5. FIG.
FIG. 8 is an explanatory diagram showing the operation of a stepped idle roller.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Fixed cylinder 5 ... Rear fixed cylinder 7 ... External fixed cylinder 13 ... Internal fixed cylinder 23 ... Internal gear ring 25 ... First wave washer 27 ... Lens side coupler 31 ... Pinion 33 ... 2nd lens group 35 3rd lens group 37 Focusing optical system holding ring 39 Lead groove 41 Interlocking pin 45 Interlocking ring 53 Stepped idler roller 55 Track ring 61 Manual focus ring 63 Roller drive ring 65 Second wave washer 67 Brush 69 Flexible printed circuit board 71 Detent mechanism 73 First annular groove 75 Second annular groove 79 Detent Ball 81 ... Coil spring L ... Optical axis

Claims (8)

A lens barrel capable of switching between an autofocus mode in which a focusing optical system is driven by a focusing control device and a manual focus mode in which a photographer drives the focusing optical system;
An operation unit for performing an operation for the driving in the manual focus mode;
In any of the auto focus mode and the manual focus mode, the focusing optical system that drives the focusing optical system in the optical axis direction by rotating about the optical axis of the focusing optical system. A drive unit;
A first annular portion that converts the drive amount of the focus control device into drive of the focus optical system drive portion; and a second annular portion that converts the operation amount of the operation portion into drive of the focus optical system drive portion. A stepped idler roller including an annular portion,
The first annular portion and the second annular portion have different diameters,
The operation portion is between a position that contacts the second annular portion of the stepped idle roller in the manual focus mode and a position that does not contact the stepped idler roller in the autofocus mode. A lens barrel that is movable. The lens barrel according to claim 1,
A fixed cylinder for holding the focusing optical system driving unit inside;
The focusing optical system driving unit moves the focusing optical system relative to the fixed cylinder,
The fixed mirror is in contact with the first annular portion of the stepped idler roller in the autofocus mode, and is not in contact with the stepped idler roller in the manual focus mode. Tube. In the lens barrel according to claim 1 or 2,
The focusing control device includes a gear ring that can rotate around the optical axis of the focusing optical system in the autofocus mode,
The gear ring contacts the stepped idler roller in any of the autofocus mode and the manual focus mode,
The lens barrel characterized in that the focusing optical system driving unit drives the focusing optical system in accordance with the rotation of the gear ring in the autofocus mode. In the lens barrel according to claim 3,
A lens barrel comprising a first wave washer for stopping the rotation of the gear ring and transmitting the operation of the operation unit to the stepped idler roller in the manual focus mode. In the lens barrel according to any one of claims 1 to 4 ,
The lens barrel, wherein the stepped idler roller is provided integrally with the focusing optical system driving unit. In the lens barrel according to any one of claims 1 to 5 ,
Switching between the autofocus mode and the manual focus mode is performed by operating the operation unit in an optical axis direction of the focusing optical system. In the lens barrel according to any one of claims 1 to 6 ,
The lens barrel characterized in that the first annular portion and the second annular portion have a rotation center in a direction perpendicular to the optical axis of the focusing optical system. In the lens barrel according to any one of claims 1 to 7 ,
The focus control device is provided in a camera to which the lens barrel is mounted.

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