JPH02201307A - Lens barrel for zoom lens - Google Patents

Abstract

PURPOSE:To miniaturize a zoom lens while having high power by allowing a 2nd lens group to move in the direction of the optical axis as to a 1st lens group by the quantity of movement by a cam mechanism more. CONSTITUTION:This zoom lens consists of a fixed lens barrel 26, a 1st moving cylinder 7 positioned in the fixed lens barrel 26, a 2nd moving cylinder 6 which holds the 1st and 2nd lens groups internally and is positioned in the 1st moving cylinder 7, and a cylindrical member 8 which drives the 2nd lens group in the direction of the optical axis. A 1st cam mechanism is provided between the fixed lens barrel 26 and 1st moving cylinder 7, a 2nd cam mechanism is arranged between the 1st moving cylinder 7 and 2nd moving cylinder 6, and a 3rd cam mechanism is provided between the 2nd moving cylinder 6 and cylindrical member 8. In this constitution, the 1st lens group which is arranged on the subject side on the optical axis moves integrally with the 2nd moving cylinder 6. When the 2nd moving cylinder 6 and cylindrical member 8 rotate relatively, on the other hand, the 2nd lens group which is arranged on the ocular side on the optical axis further moves to the 2nd moving cylinder 6 in the direction of the optical axis while a cam follower 13 constituting the 3rd cam mechanism is guided by a cam groove. Consequently, the lens barrel is miniaturized.

Description

[Detailed description of the invention] [Industrial application field]

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

[Prior art and its problems]

Recently, many autofocus single-lens cameras have been released that come standard with a zoom lens. The standard zoom lens for such cameras is generally 35mm.
Although lenses that support focal lengths from mm to 70 mm are often used, it is preferable to equip lenses with higher magnification if possible, in order to broaden the scope of photography. Furthermore, considering the portability of a zoom lens used as an interchangeable lens, it is very desirable that the zoom lens be miniaturized. However, in the case of a zoom lens barrel that has two lens groups, for example, in order to achieve high magnification, it is necessary to increase the amount of movement of the second lens group, which is located closer to the film on the optical axis. Ta. Conventionally, in the lens barrel cam system, two barrels each holding a lens group are moved independently in the axial direction by cam grooves having different lengths on the optical axis (called cam strokes). It is known that the lens is held in two cylinders, but with this type of system, 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 itself was also inevitably longer. In addition, conventionally, there have been cameras that detect the zoom position using a zoom encoder consisting of a signal board and a contact piece, read data from the memory of a microcomputer, and perform control based on that data. Because of the large amount of movement, a large signal board was required, and the installation space was also large. Therefore, this was a factor that prevented the miniaturization of the lens barrel. Furthermore, some lenses are equipped with a lens protection means at the tip of the lens barrel, which has a lens protection plate that opens and closes, but this is also a factor that hinders miniaturization. This also led to erroneous operations, such as taking pictures without changing the settings. The present invention was devised to effectively solve the conventional technical problems as described above. Therefore, the purpose is to provide a compact zoom lens barrel that is a high-magnification zoom lens, and to provide a zoom lens barrel that can detect the zoom position with a small zoom encoder. Another object of the present invention is to provide a lens barrel for a zoom lens that is miniaturized and is equipped with a lens protection means that prevents erroneous operation at its tip.

[Means to solve the problem]

The lens barrel of the zoom lens according to the present invention is configured as follows in order to achieve the above-mentioned object. That is, the lens barrel of the zoom lens according to claim 1 includes a fixed lens barrel, a first movable barrel located within the fixed lens barrel, and a first movable barrel.
The lens group and the second lens group are held inside the first lens group.
It is comprised of a second movable barrel located within the movable barrel and a cylindrical member that drives the second lens group in the optical axis direction. A first cam mechanism is provided between the fixed lens barrel and the first movable barrel,
A second cam mechanism is provided between the first movable tube and the second movable tube, and a third cam mechanism is provided between the second movable tube and the cylindrical member. The first cam mechanism includes a spiral cam groove formed on the peripheral wall of either the fixed lens barrel or the first movable barrel, and a cam follower that projects from the other peripheral wall and is guided by the cam groove. It is composed of. Further, the second cam mechanism includes a spiral cam groove formed on the peripheral wall of either the first movable cylinder or the second movable cylinder, and a spiral cam groove provided protrudingly on the peripheral wall of the other one. It is composed of a guided cam follower and a first guide means for restraining rotation of the second movable barrel relative to the fixed lens barrel. The third cam mechanism includes a spiral cam groove formed on the circumferential wall of one of the second movable cylinder and the cylindrical member, a cam groove in the optical axis direction formed on the other circumferential wall, and a second cam groove. a cam follower protruding from the lens group and guided by each of these cam grooves; and a second cam follower that restricts rotation of the cylindrical member relative to the first movable barrel.
and a guide means. In the zoom lens barrel according to the second aspect of the present invention, the cylindrical member has a zoom encoder contact piece, and the second movable barrel has a zoom encoder signal board in contact with the contact piece. This contact piece and the board constitute a zoom encoder that detects the zoom position. In the zoom lens barrel according to claim 3, the second movable barrel is provided with a lens protection means at its front end, and the lens protection means includes a first engagement protrusion that projects radially outward or axially rearward. Has a piece. On the other hand, the first movable barrel has a second engaging protrusion that protrudes inward in the radial direction of the lens, and the first engaging protrusion is located at the position where the lens is retracted, and the second engaging protrusion engage with. Further, the lens protection means includes a lens protection plate that can be opened and closed by engaging and disengaging the first engagement protrusion and the second engagement protrusion.

[Action/effect]

In the above configuration, the first movable barrel rotates around the optical axis and also moves in the optical axis direction by the cam follower forming the first cam mechanism being guided by the cam groove. The second movable barrel located inside the first movable barrel is restricted from rotating with respect to the fixed barrel by the first guide means, so it cannot rotate relative to the first movable barrel. Become. Therefore, the cam follower constituting the second cam mechanism is guided by the cam groove, and further moves in the optical axis direction while rotating around the optical axis with respect to the first moving barrel. The cylindrical member engaged with the second movable tube is restricted from rotating with respect to the first movable tube by the second guide means, so that it rotates relative to the second movable tube. It turns out. That is, the fixed lens barrel and the second movable barrel do not rotate, but the first movable barrel and the cylindrical member rotate in synchronization with respect to them. In the operation of the lens barrel of the zoom lens as described above, the first lens group disposed on the subject side on the optical axis moves integrally with the second movable barrel. On the other hand, when the second movable cylinder and the cylindrical member rotate relative to each other, the second lens group disposed on the eyepiece side on the optical axis is guided by the cam follower forming the third cam mechanism into the cam groove. Then, it moves further in the optical axis direction with respect to the second moving barrel. In other words, the second lens group moves in the optical axis direction more than the first lens group by the amount of movement by the third cam mechanism. Therefore, in the case of a conventional lens barrel held via a separate cam mechanism in two barrels each having a lens group, it is difficult to move each lens group in the optical axis direction. Although the length of the lens barrel has been limited by its size, with the above configuration, the necessary amount of movement of the lens group can be sufficiently obtained within a short lens barrel. In the zoom lens barrel according to claim 2, when the cylindrical member moves relative to the second movable barrel, the signal board and the contact piece slide, and the zoom encoder constituted by these slides. generates a zoom position signal for the lens barrel. Since the operating range of the cylindrical member is considerably smaller than that of the second lens group, the zoom encoder itself can also be made small and of a simple configuration. In the lens barrel of the zoom lens according to claim 3, the lens is retracted so that the front end portion of the lens barrel is provided with t.
The lens protection plate of the lens protection means is closed, and the lens protection plate is opened by letting out the lens. Therefore, when the camera is used, the protective plate closes and the lens is automatically protected, and when the camera is used, the protective plate opens and the protection is released, leading to erroneous operations such as taking pictures with the protective plate closed. Nor.

【Example】

An embodiment of the present invention will be described below with reference to FIGS. 1 to 9. 1 and 2 are exploded perspective views of the lens barrel of the zoom lens according to the present invention, FIG. 3 is a vertical sectional view showing the lens barrel of the zoom lens in the wide-angle state, and FIG. 4 is the telephoto state. FIG. The following explanation will be given mainly using FIGS. 1 and 3. As shown in FIG. 1, a male helicoid screw la is formed on the outer periphery of the first lens frame l that holds the first lens group. On the other hand, a female helicoid screw 2a is formed on the inner circumference of the cylindrical first lens frame holding tube 2, and the first lens frame l
It is screwed together with the male helicoid screw 1a. This holding cylinder 2 is attached to a shutter block 3 that performs focusing and exposure. At that time, although not shown, a rotatable lever of the shutter block 3 and four parts formed on the first lens frame l engage with each other. When this lever rotates, the first lens frame l also rotates, and at the same time moves in the optical axis direction by the action of the helicoid screw to focus on the subject. Further, the shutter block 3 is screwed to the forward barrel 6, which is a second movable barrel and includes a cylindrical portion 6C and a flange portion 6d, so as to operate integrally with the forward barrel 6. The second lens frame 5 holding the second lens group is inserted into the forward barrel 6 by inserting a conical first cam follower 13 forming the third cam mechanism into a cam groove formed on the peripheral wall of the cylindrical portion of the forward barrel 6. 6a, and is held in the forward cylinder 6 by screwing it to the threaded portion 5a. Cam groove 6
The arrows a are spirally formed at three locations on the peripheral wall of the advancing cylinder 6, and are wider on the outer circumferential surface side than on the inner circumferential surface side. The peripheral wall of the forward cylinder 6 is inserted into a rotating ring 8 having a zoom encoder contact piece 9 attached to its outer peripheral surface. The inner peripheral surface of the rotating ring 8 has an inner groove 8 extending along the axial direction.
a is formed, and this inner groove 8a engages with the above-mentioned first cam follower 13 located within the cam groove 6a of the forward cylinder 6. On the other hand, an outer groove 8b extending along the axial direction is formed on the outer circumferential surface of the rotary ring 8 as a cylindrical member, and this outer groove 8b is formed in the rotary advance cylinder 7 as a first movable cylinder, which will be described later. Protrusion 7b formed on the inner peripheral wall (see Figure 3)
engage with. The rotating ring 8 is held between the forward cylinder 6 and the forward cylinder 6 in the axial direction by fixing the stopper 10 and the metal fitting 11 to the forward cylinder 6 with screws, allowing only rotation. . The inner surface of the metal fitting 11 fixed around the cylindrical portion 6c of the forward cylinder 6 has a pattern contact shown in FIG. 9 (it has a conductor pattern shown by thin lines).
A flexible printed circuit board 12 for a zoom encoder (hereinafter referred to as a zoom signal board) is attached, and various lens position signals are generated by sliding this and the above-mentioned contact piece 9. On the other hand, a cylindrical barrier holding cylinder 21 is fixed to the flange portion of the forward cylinder 6 with screws. This barrier holding cylinder 21
At the front end of the lens is a barrier block 3 as a lens protection means.
1 is held, and a light shielding material 22 is adhered to the outer peripheral surface of the rear end. The barrier block 31 has a barrier operating piece 32 (biased in six directions in FIG. 2 by a spring (not shown)) as a first engaging protrusion that protrudes toward the rear end side of the cylinder. This actuating piece 32 engages with a protrusion 7b, which serves as a second engaging protrusion, formed on the rotating forward barrel 7 when the lens barrel is retracted. The forward barrel 6 which holds the first lens group, second lens group, zoom encoder, and lens barrier with the above configuration
The cylindrical rotating advance cylinder 71 is held inside the case 7. A substantially spiral cam groove 7d constituting the second cam mechanism is formed on the inner circumferential surface of the rotationally advancing barrel 7 so as to divide the circumferential surface into three equal parts. The cam groove 7d does not penetrate through the wall thickness of the rotary forward cylinder 7, but is formed as a bottomed groove on the inner surface so that the width on the opening side is wider than the width of the groove bottom. There is. Here, FIG. 5 is a developed view of the front end side of the inner surface of the rotary forward cylinder 7, and as shown in the figure, the cam groove 7d is formed so as to penetrate toward the front end side of the rotary forward cylinder 7 to form an opening. . A rectangular groove having a face end opening is formed at an intermediate position between the openings of the front end of each cam groove, and a claw 7c is formed inside the groove. The forward cylinder 6 has a boss 6b formed around the flange portion 6d, and a conical second force l to be engaged with the cam groove 7d.
After the follower 14 is attached, the cam follower 14 moves the cam R7 from the subject side (left side in FIG. 3) of the rotating forward barrel 7.
d and stored inside it. A first ring 23 is attached to the end of the rotationally advancing cylinder 7. This first ring has a locking piece 2 that projects in the axial direction from the annular member.
3a and stock/<-23b, and has a light shielding material 24 on its inner periphery. The locking piece 23a is attached to the rotationally advancing barrel 7 by engaging the hole formed in the locking piece 23a with the claw 7c. At this time, as shown in FIG. 5, the stopper 23b is fitted so as to fill the front end opening of the cam groove 7d formed in the rotation forward cylinder 7. As shown in FIG. 1, a boss 7g is formed at a position dividing the outer periphery of the rotary forward cylinder 7 into three equal parts, and a second cam follower 14, which is the same as that attached to the forward cylinder 6, is attached to this boss 7g. It is attached. The rotationally advancing barrel 7 engages the attached second cam follower 14 with cams 1126a forming a first cam mechanism formed at three locations on the inner circumferential surface of the cylindrical fixed lens barrel 26, thereby moving the attached second cam follower 14 into its interior. It will be stored. The cam [26a is a spiral groove with a bottom, similar to the cam fIt7a of the rotation forward cylinder 7 described above, and is formed wider on the opening side than the groove bottom. Further, FIG. 6 is a developed view of the front end side of the inner peripheral surface of the fixed lens barrel, and as shown in the figure, the cam groove 26a penetrates through the end of the fixed lens barrel 26 toward the surface end of the cylinder. It is formed so as to form an opening. Further, a second annular ring is attached to the front end of the fixed lens barrel 26. This second ring has a stopper 25a formed at the end of the annular member to protrude in the axial direction, and is mounted so that the stopper 25a fills the end of the cam groove 7a passing through it. As shown in FIG. 3, a light shielding material 51 is adhered to the inner surface of the second ring, similar to the first ring. A front cover 40 is attached to the tip of the fixed lens barrel so as to cover this second ring. A pair of gear holding parts 26b are formed on the outer peripheral surface of the fixed lens barrel 26 so as to face each other, as shown in FIG. It is pivoted by. On the other hand, as shown in FIG.
A gear portion 7a is formed so as to mesh with this gear 27 and rotate the rotary advance cylinder 7. Incidentally, as will be explained later, the rotary forward barrel 7 is connected to the fixed lens barrel 26 by a cam WI.
In order to move along I7d, the gear portion 7a is also formed in a spiral shape along this locus. A flange portion of a guide ring 29 composed of a cylindrical portion and a flange portion is fixed to the end portion of the fixed lens barrel 26 on the camera body 41 side with screws. This guide ring 29
The cylindrical portion fits into the inner circumferential surface of the rotating forward barrel 7, and the fixed lens barrel 2
The rotary forward cylinder 7 is held between the cylinder 6 and the cylinder 6. Further, inside this cylindrical portion, a groove portion 10 formed at the peripheral end of the stopper fitting 10 is provided.
A guide member 30 that engages with job is fixed. Regarding the zoom lens barrel configured as above,
The operation will be explained below. However, in this case, the initial state is set to the wide-angle side shown in FIG. When the zoom switch is turned on as a prerequisite for zoom operation, the rotation of the motor is transmitted to the gear 27 attached to the fixed lens barrel 26 via a reduction gear train (not shown). Therefore, the rotary advance barrel 7 rotates within the fixed lens barrel 6 due to the action of the gear portion 7a, but as the second cam follower 14 moves along the cam groove 26a, the first lens group, the second lens group, etc. It also moves in the optical axis direction together with the forward barrel 6 that holds the . By the way, the guide member 30 integrally included in the guide ring 29 screwed to the fixed lens barrel 26 is connected to the groove 10a of the stopper 10 screwed to the forward barrel 6.
, 10b, the forward rotating barrel 7 moves forward while rotating relative to the fixed barrel 26, whereas the advancing barrel 6 only moves linearly relative to the fixed barrel 26. be. Therefore, the rotation forward cylinder 7 and the forward movement cylinder 6 rotate relative to each other. As a result, the second cam follower 14 attached to the outer periphery of the flange portion 6d of the forward-moving cylinder 6 is moved to the cam 711I7d on the inner periphery of the rotating forward-moving cylinder 7.
, the advancing barrel 6 moves further forward along the optical axis inside the rotating advancing barrel 7, and moves away from the first lens group by an amount equal to this amount of movement. At this time, the rotating ring 8 located around the cylindrical portion 6c of the advancing barrel 6 moves integrally with the advancing barrel 6 in the optical axis direction, but the outer groove 8b and the protruding portion 7b of the rotating advancing barrel 7 Since they are engaged with each other, the rotary forward cylinder 7 rotates relative to the forward cylinder 6. As a result, the first cam follower 13 located within the cam groove 6a
moves along this cam groove 6a. In other words, the second lens group moves in the optical axis direction at this time as well, and the total amount of movement from the wide-angle side to the telephoto side is equal to the cam groove 26a. 7d, Ba can be said to be the sum of the amounts that the horn 2 cam follower 14.14 and the first cam follower 13 each move along the optical axis. In this way, when zooming from the wide-angle side to the telephoto side, the second lens group changes the amount of movement in the optical axis direction of the first cam follower 13 that moves within the cam groove 6a relative to the first lens group. This means that you will have to move an extra amount. Therefore, the space required in the optical axis direction to move the second lens group can be reduced to about half that of the conventional lens. In addition, in conventional configurations, in order to achieve a certain degree of cam stroke, the torsion angle of the cam groove must be reduced to reduce the amount of rotation, otherwise the zoom speed would be slow.
On the other hand, if the torsion angle was small, the operation would become unstable due to the influence of friction, but with the above configuration, the cam groove can be formed so that the zoom operation can be performed easily and quickly. Become. Further, by forming the drive gear portion in a spiral shape along the movement of the cylinder, the drive space can be kept to a minimum, and this also allows the lens barrel to be configured to be small. Furthermore, since the cam groove penetrates through the front end of the lens to form an opening, it is easy to assemble the lens. on the other hand,
At the most extended position of the lens barrel, the second cam follower, which moves within the cam groove 7d of the rotary forward cylinder 7, is moved by the first ring 2.
The cam groove 26a of the fixed lens barrel 26 is inserted into the stopper 23b of No. 3.
The second cam follower 14 moving within the second ring 25
Since the forward barrel comes into contact with the stoppers 25a, the forward barrel does not come out during zooming. Additionally, the light shielding material can be attached extremely easily. As shown in FIG. 4, during zooming, the rotary forward barrel 7 protrudes forward beyond the front cover attached to the front of the fixed lens barrel 26, but the first ring 23 is attached to the tip of the rotary forward barrel 7. Therefore, its internal structure cannot be seen. The cam grooves 6a, 7d, and 26a formed in the forward moving member 7 and the fixed lens barrel 26 are as shown in FIGS. 5 and 6, respectively, and 6a is similar to these. In terms of their functions, they are classified into a zoom operation area I and a barrier operation area (2). Assuming that the lens barrel is now in the wide-angle state, the gear 27 is moved to further retract the rotary forward barrel 7 as shown in FIG. When the rotary ring 8 is rotated in the B direction, the rotary ring 8 also rotates in the B direction with the rotation of the rotary advance cylinder 7. At this time, the barrier actuating portion 32 of the barrier block 31 that has been drawn into the body comes into contact with the protruding portion 7b of the rotary forward cylinder 7, and the barrier actuating portion 32
The barrier is closed by rotating in the direction B with the rotation of the protrusion 7b. On the other hand, with the barrier closed, the rotary advance barrel 7 is moved toward the telephoto side as shown in FIG. When rotated, the rotating ring 8 also moves along with the rotating forward cylinder 7.
Rotate in the direction. As mentioned above, since the barrier actuating section 32 is urged in the direction A by a spring (not shown),
At the stage when the cam follower is moving in the barrier operating area of the cam groove, the barrier operating portion 3 is attached to the protrusion 7b of the rotating forward barrel 7.
2 follows, during which the opening operation of the barrier takes place. When the cam follower enters the zoom operation area of the cam groove, the barrier actuating part 32 is in the barrier release side position, so it does not follow the protrusion 7b of the rotary forward cylinder 7 any more, but changes its position to the spring. It is held by a biasing force. During the extending and retracting operations of the lens barrel as described above, the rotating forward barrel 7 always moves in the optical axis direction while being fitted into the fixed lens barrel 26, and the gear portion 7a of the rotating forward barrel 7 is formed. In this position on the camera body side, the rotary forward barrel 7 is always kept in a fitted state with the guide ring 29. Therefore, the rotary advance barrel 7 is prevented from tilting with respect to the fixed lens barrel 26 due to the moment of the gear drive unit generated when the lens barrel is extended or the weight of the lens itself that is extended. Here, the operation of the zoom encoder 12 will be explained using FIG. 9. First, the rotating ring 8 is connected to the rotating forward cylinder 7.
However, since the metal fitting 11 is fixed to the forward cylinder 6, the contact piece 9 attached to the rotating ring 8 and the metal fitting 1
Relative rotation is performed between the zoom signal board 12 attached to the zoom signal board 1 and the zoom signal board 12 attached to the zoom signal board 12. FIG. 9 is a developed view of the zoom signal board 12 and the contact piece 9. When the lens barrel is in the wide-angle state, the contact piece 9 moves to position 9a shown by the solid line, and the tip of the contact piece 9 is at position S.
), and in the telephoto state, moves to position 9b indicated by a broken line (the tip of contact piece 9 moves to position X). Although not shown, the tip of the contact piece 9 moves to position U when the barrier is closed. In this way, the contact piece 9 can take various positions of X"-'Ll on the zoom signal board depending on the zoom position, but the zoom signal board 1
By contacting the pattern contacts (represented by thin lines) of the conductor pattern 2, the ground contacts A, B, C, D, and F are grounded. Each G signal is sent to a circuit within the camera through a connector H. For example, in this figure, the contact piece position 9b when the lens barrel is in the telephoto state represents the position for aligning the lens barrel and the zoom signal board, and in this case, the zoom position is set to the telephoto side. The position is adjusted by determining the continuity state between contact E and ground A when adjusted to the end, and monitoring the position at which it turns off. Note that this adjustment position does not necessarily need to be made at the telephoto end (it may be set at another position.Also, if the pattern contacts are configured as shown in this figure, the adjustment position will be adjusted as indicated by hatching in the figure). Detection of D and E to 1
Since this can be done with one tip of the section, there is no need to increase the tip of the section just for position adjustment.

[Brief explanation of the drawing]

1 and 2 are exploded perspective views of a lens barrel of a zoom lens according to an embodiment of the present invention, FIG. 3 is a longitudinal sectional view of the lens barrel of a zoom lens in a wide-angle state, and FIG. 4 is a zoom lens barrel. 5 is a developed view of the end of the rotary advancing section, FIG. 6 is a developed view of the front end of the fixed lens barrel, and FIG. Figure 8 is a right side view of Figure 3 in the zoom operation state (only inside the rotating forward barrel), Figure 9 is a developed view of the zoom encoder. It is. l...second lens frame, la...male helicoid screw,
2... Second lens frame holding cylinder, 2a... Female helicoid screw, 3... Shutter block, 5... Second lens frame, 5a... Threaded portion, 6... Second movement Advance cylinder as cylinder, 6a... cam groove as third cam mechanism, 6b
...Boss, 6c...Cylindrical part, 6d...Flange part, 7...Rotating advance cylinder constituting the first moving cylinder, 7a...
・Gear part, 7b...Protrusion as second engaging protrusion, 7c
...Claw, 7d...Cam groove that constitutes the second cam mechanism,
7g...Boss, 8...Rotating ring as a cylindrical member, 8a...Inner groove forming the third cam mechanism, 8b...
Outer groove constituting the second guide means, 9... zoom encoder contact piece, 10... stopper, 10a, job...
- Reservoir, 2, which constitutes the first guide means...Metal fitting, 12
...Flexible printed circuit board for zoom encoder, 13...First cam follower constituting the third cam mechanism, 14... First cam follower. Second cam follower constituting the second cam mechanism 21... Barrier holding tube, 22... Light shielding material, 23... First ring, 23a... Locking piece, 23b
... stopper, 24 ... light shielding material, 25 ... second
Ring, 25a... Stotuber, 26... Fixed lens barrel, 26a... Cam groove constituting the first cam mechanism, 26b
... Gear holding part, 27 ... Gear, 28 ... Pin,
29... Guide ring, 30... Guide member constituting the first guide means, 31... Barrier block as lens protection means, 32... Barrier actuation piece as the first engagement protrusion, 40・・Front cover, 41 ・・Body, 42
・Film, 51・Light-shielding material patent applicant Minolta Camera Co., Ltd. Agent
Person Patent Attorney Maeda 葆 (H state name) Figure 3 Figure 5 Figure 7 A Figure 6 Figure 8

Claims (3)

[Claims] (1), a fixed lens barrel (26), a first movable barrel (7) located within the fixed lens barrel (26), a first lens group and a second lens group;
It consists of a second movable barrel (6) that holds the lens group therein and is located within the first movable barrel (7), and a cylindrical member (8) that drives the second lens group in the optical axis direction. , a first cam mechanism (
26a, 14), and a second cam mechanism (7d, 10a, 10) between the first movable barrel (7) and the second movable barrel (6).
b, 14, 30), and a third cam mechanism (6a, 7b, 8a,
8b, 13), and the first cam mechanism (26a, 14) includes the fixed lens barrel (
26) and a spiral cam groove (26a) formed on the circumferential wall of one of the first movable cylinders (7), and a helical cam groove (26a) protruding from the other circumferential wall and guided by the cam groove (26a). The second cam mechanism (7d, 10a, 10b, 14, 30
) is a spiral cam groove (7d) formed on the peripheral wall of either one of the first movable cylinder (7) or the second movable cylinder (6), and a spiral cam groove (7d) protruding from the peripheral wall of the other one. Cam groove (7d)
a cam follower (14) guided by a cam follower (14), and a first guide means (10a, 10b, 30) for restraining the rotation of the second movable barrel (6) with respect to the fixed lens barrel (26); The cam mechanism (6a, 7b, 8a, 8b, 13) is
A spiral cam groove (6a) formed on the peripheral wall of either the second movable cylinder (6) or the cylindrical member (8), and a cam groove in the optical axis direction formed on the other peripheral wall. (8a), and each of the cam grooves (6a, 6a) protruding from the second lens group.
8a), and second guide means (7b, 8b) for restraining rotation of the cylindrical member (8) relative to the first movable cylinder (7). The lens barrel of a zoom lens. (2), the cylindrical member (8) has a zoom encoder contact piece (9), and the second movable cylinder (6) has a zoom encoder signal board (12) in contact with the contact piece; 2. A zoom lens barrel according to claim 1, wherein the contact piece (9) and the substrate (12) constitute a zoom encoder for detecting a zoom position. (3) The second movable barrel (6) is provided with a lens protection means (31) at its front end, and the lens protection means (31) has a first engagement protrusion that protrudes radially outward or axially rearward. The first movable tube (7) has a second engagement protrusion (7b) projecting inward in the radial direction of the tube, and the first movable tube (7) has a second engagement protrusion (7b) that protrudes inward in the radial direction of the tube. is engaged with the second engaging protrusion (7b) at the position where the lens is retracted, and the lens protection means (
31) is the first engaging protrusion (32) and the second engaging protrusion (
3. The zoom lens barrel according to claim 1, further comprising a lens protection plate whose opening and closing are switched by engaging with and disengaging from the lens protection plate 7b).