JP2773182B2 - Zoom lens barrel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a zoom lens barrel having two lens groups.

[Prior art and its problems]

Recently, there have been many autofocus single-lens reflex cameras equipped with a zoom lens as a standard feature. As a standard zoom lens for such cameras, generally 35
Although a device corresponding to a focal length of about mm to 70 mm is often used, it is preferable to provide a device having a higher magnification if possible from the viewpoint of expanding the width of photography. In addition, it is very preferable that a zoom lens used as an interchangeable lens be miniaturized in view of its portability. However, for example, in the case of a lens barrel of a zoom lens having two lens groups, in order to achieve high magnification, the amount of movement of the second lens group disposed near the predetermined image plane on the optical axis in optical theory is required. I had to do more. Conventionally, as a lens barrel cam system, two cylinders each holding a lens group are separately moved in the optical axis direction by cam grooves having different lengths on the optical axis (referred to as cam strokes). It is known that the lens barrel is held in one cylinder, but in such a method, the cam stroke had to be increased in order to increase the amount of movement of the lens group in the optical axis direction. The length of itself was inevitably longer. Conventionally, there has been a camera that detects a zoom position by a zoom encoder including a signal substrate and a contact piece, reads data from a memory of a microcomputer, and performs control based on the data. A large signal board was required due to the large moving distance, and the mounting space was also large. Therefore,
This was one of the factors that hindered the miniaturization of the lens barrel. Further, there is a lens barrel provided with a lens protection means having a lens protection plate that opens and closes, which is also a factor that prevents miniaturization, and furthermore, the protection plate is closed. Incorrect shooting, such as shooting while still in motion. The present invention has been made to effectively solve the conventional technical problems as described above. Therefore, the object is to provide a zoom lens barrel that is downsized while being a high magnification zoom lens, and to provide a zoom lens barrel that can detect a zoom position with a small zoom encoder. It is still another object of the present invention to provide a zoom lens barrel provided with a lens protection means which does not cause an erroneous operation at the tip of the lens barrel which has been miniaturized.

[Means for Solving the Problems]

A lens barrel of a zoom lens according to the present invention is configured as described below to achieve the above object. That is, the lens barrel of the zoom lens according to the first aspect includes a fixed lens barrel, a first movable cylinder located in the fixed lens barrel, and a first lens group and a second lens group held therein. It comprises a second movable cylinder located in one movable cylinder, and an upper cylinder member for driving the second lens group in the optical axis direction. A first cam mechanism is provided between the fixed barrel and the first movable barrel, and a second cam mechanism is provided between the first movable barrel and the second movable barrel. A third cam mechanism is provided between the members. The first cam mechanism has a spiral first cam groove formed on one of the peripheral walls of the fixed barrel and the first movable barrel, and is protruded from the other peripheral wall to be guided by the cam groove. And a first cam follower. The second cam mechanism includes a spiral second cam groove formed on one of the peripheral walls of the first movable cylinder and the second movable cylinder.
It comprises a second cam follower protruding from one of the other peripheral walls and guided by the cam groove, and a first guide means for restricting the rotation of the second movable cylinder with respect to the fixed lens barrel. The third cam mechanism includes a spiral third cam groove formed on one of the peripheral walls of the second movable cylinder and the cylindrical member, and a fourth cam groove formed on one of the other peripheral walls in the optical axis direction. And the second
It comprises a third cam follower protruding from the lens group and guided by the third and fourth cam grooves, and a second guide means for restricting the rotation of the cylindrical member with respect to the first movable cylinder. . In the zoom lens barrel according to the second aspect, the cylindrical member has a zoom encoder contact piece, and the second movable cylinder has a zoom encoder signal board in contact with the contact piece. The contact piece and the substrate constitute a zoom encoder that detects a zoom position. In the lens barrel of the zoom lens according to the third aspect, the second movable barrel is provided with a lens protecting means at a front end thereof, and the lens protecting means is provided with a first engaging projection projecting radially outward or axially rearward. Has a piece. On the other hand, the first movable cylinder has a second engagement projection that projects inward in the radial direction of the cylinder, and the first engagement projection is the second engagement projection at the position where the lens is retracted. Engage with. The lens protection means includes a lens protection plate that can be opened or closed by engagement and disengagement of the first engagement protrusion and the second engagement protrusion.

[Action / Effect]

In the above configuration, the first moving cylinder also moves in the optical axis direction while rotating around the optical axis by guiding the first cam follower constituting the first cam mechanism into the first cam groove. The second moving cylinder located inside the first moving cylinder is:
Since the fixed lens barrel is regulated by the first guide means so as not to rotate, it rotates relatively to the first movable barrel. Therefore, the second cam mechanism
The cam follower will be guided to the second cam groove,
It also moves in the optical axis direction while rotating around the optical axis with respect to the first moving cylinder. Since the cylindrical member engaged with the second movable cylinder is regulated by the second guide means so as not to rotate with respect to the first movable cylinder, it rotates relatively with respect to the second movable cylinder. Will be. That is, the fixed barrel and the second movable barrel do not rotate, but the first movable barrel and the tubular member rotate in synchronization with each other. In the operation of the lens barrel of the zoom lens as described above, the first lens group arranged on the object side on the optical axis moves integrally with the second movable cylinder. On the other hand, when the second movable cylinder and the cylindrical member relatively rotate, the second lens group arranged on the side of the expected image forming plane on the optical axis has the third cam follower constituting the third cam mechanism. Guided by the third and fourth cam grooves, the second
It further moves in the optical axis direction with respect to the moving cylinder. That is,
The second lens group moves further in the optical axis direction than the first lens group by the movement of the third cam mechanism. Therefore, two cylinders each having a lens group are 1
In the case of a conventional lens barrel held in a single cylinder via a separate cam mechanism, the length of the lens barrel is limited by the amount of movement of each lens group in the optical axis direction. But,
According to the above configuration, the necessary movement amount of the lens group can be sufficiently obtained in the short lens barrel. In the zoom lens barrel according to claim 2, when the cylindrical member moves relative to the second movable cylinder, the signal substrate and the contact piece slide, and a zoom encoder configured by these components. Generates a zoom position signal for the lens barrel. Since the operating range of the cylindrical member is considerably smaller than the operating range of the second lens group, the zoom encoder itself can be small and have a simple configuration. In the lens barrel of the zoom lens according to the third aspect, when the lens is retracted, the lens protection plate of the lens protection means provided at the front end of the lens barrel is closed, and when the lens is extended, the lens is protected. The board is opened. Therefore, when the camera is not used, the protection plate is closed and the lens is automatically protected, and when used, the protection plate is opened and the protection is released, and an erroneous operation such as taking a picture with the protection plate closed is performed. Not even.

【Example】

Hereinafter, one embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to the drawings. 1 and 2 are exploded perspective views of a lens barrel of a zoom lens according to the present invention, FIG. 3 is a longitudinal sectional view showing a state where the lens barrel of the zoom lens is in a wide angle state, and FIG. FIG. Hereinafter, description will be made mainly with reference to FIGS. 1 and 3. As shown in FIG. 1, a male helicoid screw 1a is formed on the outer periphery of the first lens frame 1 holding the first lens group. On the other hand, a female helicoid screw 2 a is formed on the inner periphery of the cylindrical first lens frame holding cylinder 2, and is screwed with the male helicoid screw 1 a of the first lens frame 1. The holding cylinder 2 is mounted on a shutter block 3 for performing focusing and exposure.
At this time, although not shown, a lever rotatably provided in the shutter block 3 and a concave portion formed in the first lens frame 1 are engaged. When this lever rotates, the first lens frame 1 also rotates, and at the same time, moves in the direction of the optical axis by the action of the helicoid screw to focus on the subject. Further, the shutter block 3 is screwed to the forward barrel 6 so as to operate integrally with the forward barrel 6 as a second movable barrel comprising a cylindrical portion 6c and a flange 6d. The second lens frame 5 holding the second lens group is provided inside the advance barrel 6 with a third cam mechanism (a first cam mechanism and a second cam mechanism).
A conical third cam follower 13 (the first cam follower and the second cam follower will be described later) constituting the cam mechanism will be described later. The third cam groove 6a (the After the first cam groove and the second cam groove are fitted into each other), they are screwed to the threaded portion 5a and are held by the forward barrel 6. The third cam grooves 6a are spirally formed at three places on the peripheral wall of the advance cylinder 6, and are formed wider on the outer peripheral surface side than on the inner peripheral surface side of the cylinder. The peripheral wall of the forward barrel 6 is inserted into a rotary ring 8 having a zoom encoder contact piece 9 attached to its outer peripheral surface.
The inner circumferential surface of the rotating ring 8 has an inner groove 8a in a direction along the axial direction.
The inner groove 8a is formed in the third cam groove of the forward cylinder 6.
The third cam follower 13 located within 6a is engaged. On the other hand, an outer groove 8b extending in the axial direction is formed on the outer peripheral surface of the rotating ring 8 as a cylindrical member, and this outer groove 8b is used for a rotating forward cylinder 7 as a first moving cylinder described later.
Engages with a projection 7b (see FIG. 3) formed on the inner peripheral wall. The rotating ring 8 is fixed to the forward barrel 6 by screwing the stopper 10 and the bracket 11 to the forward barrel 6.
Are held in the axial direction, and only rotation is allowed. A flexible printed circuit board 12 for a zoom encoder having a pattern contact (having a conductor pattern shown by a thin line) shown in FIG. (Hereinafter, abbreviated as a zoom signal substrate) is attached, and various lens position signals are generated by sliding the contact piece 9 with the above. On the other hand, a cylindrical barrier holding cylinder 21 is screwed to the flange portion of the advance cylinder 6. A barrier block 31 as lens protection means is held at the front end of the barrier holding cylinder 12, and a light shielding material 22 is adhered to the outer peripheral surface of the rear end. The barrier block 31 has a barrier actuating piece 32 (biased in a direction A in FIG. 2 by a spring (not shown)) as a first engaging projection projecting toward the rear end of the cylinder. When the lens barrel is retracted, this operating piece 32 is
Engages with the projection 7b as a second engagement projection formed at the end of the projection. The forward barrel 6 holding the first lens group, the second lens group, the zoom encoder, and the lens barrier in the above-described configuration is held inside the cylindrical rotary forward barrel 7 inside the barrel 7. A substantially helical second cam groove 7d constituting a second cam mechanism is formed on the inner peripheral surface of the rotary advancing cylinder 7 so as to divide the peripheral surface into three equal parts. This second cam groove 7d does not penetrate the thickness of the cylinder of the rotary advancing cylinder 7, but as a groove with a bottom,
The inner surface is formed such that the width on the opening side is wider than the width on the groove bottom. Here, FIG. 5 is a development view of the front end side of the inner surface of the rotary advancing cylinder. As shown, the second cam groove 7d is formed so as to penetrate to the front end side of the rotary advancing cylinder 7 to form an opening. ing. A rectangular groove having a front end opening is formed at an intermediate position between the openings at the front end of each cam groove, and a claw 7c is formed inside the groove. After the conical second cam follower 15 to be engaged with the second cam groove 7d is mounted on the boss 6b formed around the flange portion 6d, the advance cylinder 6 The rotating forward barrel 7 is guided by the second cam groove 7d from the subject side (the left side in FIG. 3) and housed therein. Then, a first ring 23 is attached to an end of the rotary advancing cylinder 7. The first ring is formed with a locking piece 23a and a stopper 23b that protrude from the annular member in the axial direction, and has a light shielding material 24 on the inner periphery thereof. Then, the hole formed in the locking piece 23a is engaged with the claw 7c, so that it is mounted on the rotary advance cylinder 7. At this time, as shown in FIG. 5, the stopper 23b is fitted so as to fill the front end opening of the second cam groove 7d formed in the rotary advancing barrel 7. A boss 7g (FIG. 3) is formed at a position where the outer periphery of the rotary advancing barrel 7 is divided into three equal parts, and the boss 7g is composed of the same components as the second cam follower 15 attached to the advancing barrel 6. The first cam follower 14 is attached. The rotary advancing barrel 7 engages the attached first cam follower 14 with a first cam groove 26a that forms a first cam mechanism and is formed at three places on the inner peripheral surface of a cylindrical fixed lens barrel 26. Is stored inside. The first cam groove 26a is provided with the rotary advance cylinder 7 described above.
Like the second cam groove 7d, the groove is a spiral bottomed groove, and the opening side is formed wider than the groove bottom. FIG. 6 is an exploded view of the front end side of the inner peripheral surface of the fixed lens barrel. As shown in the figure, the first cam groove 26a extends from the end of the fixed lens barrel 26 toward the front end side of the cylinder. It is formed so as to penetrate and form an opening. An annular second ring 25 is attached to the front end of the fixed lens barrel 26. The second ring 25 is formed with a stopper 25a projecting in the axial direction at the end of the annular member, and is mounted so that the stopper 25a fills the end of the penetrated first cam groove 26a. As shown in FIG. 3, a light shielding material 51 is adhered to the inner surface of the second ring 25 in the same manner as the first ring. The front cover 40 is attached to the tip of the fixed lens barrel so as to cover the second ring.
Is installed. As shown in FIG. 2, a pair of gear holding portions 26b are formed on the outer peripheral surface of the fixed lens barrel 26 so as to face each other.
Is supported by On the other hand, as shown in FIG. 1, a gear portion 7a is formed on the outer peripheral surface of the rotary advancing barrel 7 so as to mesh with the gear 27 and rotate the rotary advancing barrel 7. Since the rotary advancing barrel 7 moves along the first cam groove 26a with respect to the fixed lens barrel 26 as described later, the gear portion 7a is also formed helically along this locus. . A flange portion of a guide ring 29 composed of a cylindrical portion and a flange portion is fixed to an end of the fixed lens barrel 26 on the camera body 41 side by screwing. The cylindrical portion of the guide ring 29 is fitted to the inner peripheral surface of the rotary advancing barrel 7 to clamp the rotary advancing barrel with the fixed lens barrel 26. A guide member 30 that engages with the grooves 10a and 10b formed on the peripheral end of the stopper 10 is fixed inside the cylindrical portion. The operation of the lens barrel of the zoom lens configured as described above will be described below. However, in this case, the initial state is the wide angle side shown in FIG. When the zoom switch is turned on as a premise of the zoom operation, the rotation of the motor is transmitted to the gear 27 mounted on the fixed lens barrel 26 via a reduction gear train (not shown). Therefore, the rotating forward barrel 7 is moved by the action of the gear portion 7a.
26, but the first cam follower 14
By moving along 26a, it also moves in the optical axis direction with the forward barrel 6 holding the first reds group, the second lens group, and the like. By the way, since the guide member 30 integrally formed by the guide ring 29 screwed to the fixed lens barrel 26 is engaged with the grooves 10a and 10b of the stopper 10 screwed to the forward barrel 6, the rotation While the barrel 7 advances while rotating with respect to the fixed barrel 26, the forward barrel 6 is a fixed barrel.
For 26, it only moves linearly. Therefore, in the relationship between the rotating forward barrel 7 and the forward barrel 6, they rotate relatively. As a result, the flange portion 6d
The second cam follower 15 mounted on the outer periphery of the cylinder slides in the second cam groove 7d on the inner periphery of the rotary advancing barrel 7, and the advancing barrel 6 moves further forward along the optical axis in the rotary advancing barrel 7. The first lens group also moves by the same amount. At this time, the rotary ring 8 located around the cylindrical portion 6c of the forward barrel 6 moves integrally with the forward barrel 6 in the optical axis direction, but the outer groove 8b and the projection 7b of the rotary forward barrel 7 move. Due to the engagement, it rotates relatively to the forward barrel 6 together with the rotary forward barrel 7. Thus, the third cam follower 13 located in the third cam groove 6a moves along the third cam groove 6a. That is, the second lens group also moves in the optical axis direction at this time, and the total amount of movement from the wide-angle side to the telephoto side is within each of the cam grooves 26a, 7d, and 6a. , 15 and the third cam follower 13 can be said to be the sum of the amounts moved along the optical axis. As described above, when zooming from the wide-angle side to the telephoto side, the second lens group moves in the optical axis direction of the third cam follower 13 moving in the third cam groove 6a with respect to the first lens group. It moves extra by the amount of movement. Therefore, the space in the optical axis direction required for moving the second lens group can be reduced to about half of the conventional space. Also, in the conventional configuration, in order to increase the cam stroke to a certain extent, the zoom speed becomes slow unless the rotation angle of the moving cylinder is reduced by reducing the torsion angle of the cam groove. The operation was unstable due to the influence, but in the case of the above configuration,
The cam groove can be formed so that the zoom operation is easy and can be performed promptly. Further, since the driving gear portion is formed in a spiral shape along the movement of the cylinder, the driving space can be minimized, and thus the lens barrel can be made smaller. Further, since the cam groove penetrates through the front end of the cylinder to form an opening, it is easy to incorporate the lens. On the other hand, at the position where the lens barrel is extended most, the second cam follower 15 moving in the second cam groove 7d of the rotary advancing barrel 7 is in the first position.
The first cam groove 2 of the fixed lens barrel 26 is attached to the stopper 23b of the ring 23.
Since the first cam followers 14 that move inside 6a abut against the stoppers 25a of the second ring 25, the forward barrel does not come off during zooming. Also, the attachment of the light shielding material can be performed very easily. As shown in FIG. 4, when zooming, the rotary advancing barrel 7 projects forward from the front cover mounted on the front part of the fixed lens barrel 26, but is mounted on the tip of the first ring 23 rotary advancing barrel 7. So that its internal structure is not visible. Each of the cam grooves 6a, 7d and 26a formed in the forward barrel 6, the rotary forward barrel 7 and the fixed barrel 26 has, as shown in FIGS. 5 and 6 for 7d and 26a, and Similarly, the operation is classified into a zoom operation area I and a barrier operation area II. Now, assuming that the lens barrel is in the wide-angle state, the gear 27 is further retracted into the rotary advance cylinder 7,
When the inside of the rotary advancing barrel is rotated in the B direction in FIG. 7 (a view of the inside of the rotary advancing barrel from the film surface 42 side during the barrier operation), the rotating ring 8 also rotates in the B direction with the rotation of the rotary advancing barrel 7. . At this time, the barrier block pulled into the body side
The barrier closing portion 32 is brought into contact with the projection 7b of the rotary advancing cylinder 7 and the barrier operation portion 32 is rotated in the direction B with the rotation of the projection 7b, thereby closing the barrier. . On the other hand, with the barrier closed, move the rotary advancing barrel 7 to the telephoto side in the direction A in FIG. 8 (a view of the inside of the rotary advancing barrel from the film surface 42 side during the zoom operation). When rotated, the rotating ring 8 also moves along with the rotating forward barrel 7 to A
Rotate in the direction. As described above, since the barrier operating portion 32 is urged in the direction A by a spring (not shown), the projection of the rotary advancing barrel 7 is at a stage where the cam follower is moving in the barrier operating region of the cam groove. The barrier operation part 32 follows 7b, during which the opening operation of the barrier is performed. When the cam follower enters the zoom operation area of the cam groove, the barrier operating portion 32 is located at the barrier open side, so that it does not follow the protrusion 7b of the rotary advancing barrel 7 any further, and the position is set by a spring. Hold by power. During the extension and retraction operations of the lens barrel as described above, the rotary advancing barrel 7 always moves in the optical axis direction while being fitted to the fixed barrel 26, and the gear portion 7a of the rotary advancing barrel 7 is formed. In this position on the camera body side, the rotary advancing barrel 7 is always kept fitted with the guide ring 29. Therefore, the rotation-advancing barrel 7 is prevented from tilting with respect to the fixed barrel 26 due to the moment of the gear drive unit generated when the barrel is extended and the weight of the extended lens itself. Here, the operation of the zoom encoder 12 will be described with reference to FIG. First, the rotating ring 8 is
However, since the metal fitting 11 is fixed to the forward barrel 6, the relative position between the contact piece 9 attached to the rotating ring 8 and the zoom signal board 12 attached to the metal fitting 11 is relatively large. Rotation is performed. FIG. 9 is an exploded view of the zoom signal substrate 12 and the contact piece 9. When the lens barrel is in the wide-angle state, the contact piece 9 moves to a position 9a indicated by a solid line (the tip of the contact piece 9 moves to a position s). ,
In the telephoto state, it moves to the position 9b indicated by the broken line (the tip of the contact piece 9 moves to the position x). Then, although not shown, when the barrier is closed, the tip of the contact piece 9 moves to the position u. As described above, the contact piece 9 can take each of the positions x to u on the zoom signal board depending on the zoom position. At these positions, the pattern contacts of the conductor pattern of the zoom signal board 12 (represented by thin lines). , The signals of A, B, C, D, F, and G, which are ground contacts, are sent to the circuit in the camera through the connector H. For example, in this figure, the position 9b of the contact piece when the lens barrel is in the telephoto state represents a position for aligning the lens barrel with the zoom signal board. In this case, the zoom position is set to the telephoto side. With the end adjusted, the state of conduction between the contact E and the ground A is determined, and the position where it is turned off is monitored to adjust the position. Note that this adjustment position does not necessarily need to be performed at the telephoto end, and may be set at another position. Further, if the pattern contacts are configured as shown in this figure, D and E can be detected at the tip of one contact piece as distinguished by hatching in the figure. There is no need to increase the tip.

[Brief description of the drawings]

1 and 2 are exploded perspective views of a lens barrel of a zoom lens according to one embodiment of the present invention, FIG. 3 is a longitudinal sectional view of the zoom lens when the lens barrel is in a wide angle state, and FIG. 4 is a zoom lens. FIG. 5 is a developed view of the front end of the rotary advancing barrel, FIG. 6 is a developed view of the front end of the fixed barrel, and FIG. 7 is FIG. 3 in a barrier operating state. FIG. 8 is a right side view of FIG. 3 (only inside than the rotary forward barrel) in a zoom operating state, and FIG. 9 is a development view of a zoom encoder. is there. 1 ... First lens frame, 1a ... Male helicoid screw, 2 ...
1st lens frame holding cylinder, 2a ... female helicoid screw, 3 ...
Shutter block, 5: second lens frame, 5a: screw portion, 6: forward cylinder as second moving cylinder, 6a: third cam groove constituting the third cam mechanism, 6b: boss, 6c ...... Cylindrical part, 6d ... Flange part, 7 ... Rotating and advancing cylinder constituting the first moving cylinder, 7a ... Gear part, 7b ... Protrusion as second engaging projection, 7c ... Claw, 7d ... A second cam groove constituting a second cam mechanism, 7g a boss, 8 a rotating ring as a cylindrical member, 8a an inner groove as a fourth cam groove constituting a third cam mechanism, 8b ... Outer groove constituting the second guide means, 9 contact piece for zoom encoder, 10 stopper, 10a, 10b
... Grooves constituting the first guide means, 11 metal fittings, 12.
Flexible printed circuit board for zoom encoder, 13…
... the third cam follower constituting the third cam mechanism, 14 ...
A first cam follower constituting the first cam mechanism, 15 a second cam follower constituting the second cam mechanism, 21 a barrier holding cylinder, 22 a light shielding material, 23 a first ring, 23a ...
Locking piece, 23b Stopper, 24 Light shielding material, 25 Second ring, 25a Stopper, 26 Fixed lens barrel, 26a
.., A first cam groove constituting a first cam mechanism, 26 b, a gear holding portion, 27, a gear, 28, a pin, 29, a guide ring,
30: a guide member constituting the first guide means, 31: a barrier block as lens protection means, 32: a barrier operation piece as a first engagement projection, 40 ... a front cover, 41 ...
Body, 42: Film surface, 51: Light shielding material

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Haruo Kobayashi 2-30, Azuchicho, Higashi-ku, Osaka-shi, Osaka Inside Osaka International Building Minolta Camera Co., Ltd. (56) References JP-A-63-271306 (JP, A) 63-284511 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G02B 7/04 G02B 7/08 G02B 7/10

Claims (3)

(57) [Claims] 1. A fixed lens barrel (26), a first movable barrel (7) located in the fixed lens barrel (26), a first lens group and a second lens barrel.
A second moving barrel (6), which holds the lens group therein and is located in the first moving barrel (7), and a cylindrical member (8) for driving the second lens group in the optical axis direction. A first cam mechanism (26a, 14) is provided between the fixed barrel (26) and the first movable barrel (7), and the first movable barrel (7) and the second
A second cam mechanism (7d, 10a, 10b, 15, 3) is provided between the movable cylinders (6).
0), a third cam mechanism (6a, 7b, 8a, 8b, 13) is provided between the second moving cylinder (6) and the cylindrical member (8), and the first cam mechanism (26a, 14) is a spiral first cam groove (26a) formed on one of the peripheral walls of the fixed lens barrel (26) and the first movable barrel (7), and protrudes from one of the other peripheral walls. And a first cam follower (14) guided by the first cam groove (26a), and the second cam mechanism (7d, 10a, 10b, 15, 30) is connected to the first moving cylinder (7). And a spiral second cam groove (7d) formed on one of the peripheral walls of the second movable cylinder (6), and protrudingly provided on one of the other peripheral walls and guided to the second cam groove (7d). A second cam follower (15), and first guide means (10a, 10b, 30) for restraining rotation of the second movable barrel (6) with respect to the fixed lens barrel (26). The cam mechanism (6a, 7b, 8a, 8b, 13) A helical third cam groove (6a) formed on one of the peripheral walls of the moving cylinder (6) and the cylindrical member (8), and a fourth cam in the optical axis direction formed on one of the other peripheral walls. A groove (8a), a third cam follower (13) protruding from the second lens group and guided by the third and fourth cam grooves (6a, 8a),
A lens barrel for a zoom lens, comprising second guide means (7b, 8b) for restraining rotation of the cylindrical member (8) with respect to the first movable cylinder (7). 2. The tubular member (8) has a contact piece (9) for a zoom encoder, and the second movable barrel (6) has a signal board (12) for a zoom encoder that contacts the contact piece. ,
2. A zoom lens barrel according to claim 1, wherein said contact piece and said substrate constitute a zoom encoder for detecting a zoom position. 3. The second movable cylinder (6) has a lens protection means (31) at a front end thereof, and the lens protection means (31) is a first engagement projecting radially outward or axially rearward. The first moving cylinder (7) has a second engaging projection (7b) projecting radially inward of the cylinder, and the first moving cylinder (7) has a projection (32). ) Engages with the second engagement projection (7b) at the position where the lens is retracted, and the lens protection means (31)
The lens protection plate according to claim 1 or 2, further comprising a lens protection plate that can be opened and closed by engagement and disengagement of the first engagement protrusion (32) and the second engagement protrusion (7b). Zoom lens barrel.