JPH0481829A - Zoom lens barrel - Google Patents

Abstract

PURPOSE:To allow the efficient opening and closing of a lens cover by connecting a lens cover member and a focusing lens group driving member and driving the focusing lens group beyond the focusing operation range in the focal length state thereof. CONSTITUTION:The power source is turned on and a motor M for AF is started to move the 2nd lens group L2 for focusing to a very close position and to turn a cover driving ring 15 clockwise gamma. A driving arm 15a is then turned clockwise gamma as well and, therefore, an engaging arm 19a is turned by the tightening elastic force of a coil spring 25 in follow up thereto, by which a cam ring 19 is turned clockwise gamma around the optical axis O. An opening/closing pin 22 held in pressurized contact with the top of the partial arc surface 20b of the cam hole 20 is pushed upward by an inclined cam surface 20a as shown by a solid line. The lens cover member 18 is turned clockwise around a supporting pin 17b, by which an aperture 17a is opened.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a zoom lens barrel, more specifically, a lens protection cover that opens and closes in front of the photographic lens at the front of a photographic lens barrel having a zoom lens. The present invention relates to a cover opening/closing means in a lens barrel having the present invention.

[Prior Art] Recently, most ordinary cameras using silver halide film and video cameras using magnetic recording media have a photographic lens with a variable focal length, such as a zoom lens, and
The camera has a lens protection cover member (hereinafter referred to as a lens cover) that exposes the front end surface of the photographing lens to the outside when the camera is in use, and covers the front end surface of the lens when the camera is not in use.

Therefore, this type of camera has a built-in mechanism that automatically controls opening and closing of the lens cover provided at the front end of the photographic lens barrel.

The second lens cover opening/closing control mechanism is conventionally disclosed in Japanese Patent Application Laid-Open No. 63-95426 (US Pat. No. 4,806,961).
), the lens cover is opened and closed using the electric power of a zoom motor, as disclosed in Japanese Patent Laid-Open No. 64
A device that opens and closes a lens cover using the electric power of an AF (autofocus) motor is already known, as described in Japanese Patent No. 65531.

That is, in the camera disclosed in Japanese Patent Application Laid-Open No. 63-95426, the driving force of the zoom motor is transmitted as rotation of the cam barrel to the drive ring of the lens cover to open and close the lens cover. The lens cover is opened and closed by transmitting the movement of a member linked to the focal length switching operation to the cover drive ring. Specifically, the lens cover is opened and closed by the focal length switching mechanism that switches the focal length of the photographic lens. A drive barrel is provided to link the mechanism to the motor, and a relatively long inclined cam slot for switching and a cam slot for opening/closing that is connected to the same slot and oriented perpendicular to the optical axis are drilled in the drive barrel. The tilted switching cam slot drives the focal length switching mechanism, and the opening/closing cam slot drives the lens cover opening/closing mechanism.

Furthermore, the autofocus camera disclosed in Japanese Patent Application Laid-Open No. 64-65531 is configured so that the lens can be moved beyond the normal lens movement range, that is, from close range to the The lens is moved to the extra moving area by the rotational driving force of the motor via a member linked to the motor, and the lens cover is opened and closed using this movement.

[Problems to be Solved by the Invention] However, the conventional lens cover opening/closing means described above has the following drawbacks.

That is, in the above-mentioned Japanese Patent Application Laid-open No. 63-95426,
There is a constraint that the stop position of the zoom lens must have an off position or a retracted position beyond the wide position, and in addition, the opening/closing cam groove hole drilled in the drive barrel as an interlocking member must be made somewhat long. This is disadvantageous in terms of the strength of the switching slanted cam slot and the drive barrel, and in particular, arranging a large interlocking member such as the drive barrel inside the lens barrel goes against the desire to make the camera more compact. . In other words, this technical means requires a movement to open and close the lens cover in addition to the movement to actually change the focal length, so the rotation angle of the drive cylinder (cam cylinder) becomes very large, and the interlocking member The drawback is that the size of the lens frame becomes large due to the need for space for movement.

Further, in the technical means of the above-mentioned Japanese Patent Application Laid-Open No. 64-65531, the barrier member which is the lens cover and the barrier opening/closing member driven by the focus control motor are always engaged,
In addition to the possibility that the relative positions of the barrier member and the barrier opening/closing member may change due to zooming operations, there is also the problem that the lens barrel becomes larger because the lens is moved more than necessary.

Therefore, an object of the present invention is to provide a zoom lens barrel that can effectively utilize the unique properties of a zoom lens, eliminate the drawbacks of the conventional lens cover opening/closing means, and efficiently open and close the lens cover. It is on offer.

Means and Effects for Solving Problem 1 In a zoom lens employing an inner focus method, the amount of movement for driving the focusing lens from ■ to close range differs depending on each focal length. In other words, Lw is the amount of lens movement to extend the focusing lens group from the bacteria to a close distance in the short focus state W, and S is the standard state S.
If the amount of movement from ■ to a close distance is Ls, and the amount of movement from ■ to a close distance in a long focus state T is Lt, then generally Lw<Ls<Lt.

Therefore, the focusing mechanism that moves out the focusing lens group is configured so that the focusing lens group moves at least within the range of the largest movement amount Lt. Therefore, in the focus mechanism configured in this way, in the short focus state W, the amount of movement of the focusing lens group is smaller by Lt-Lw.

The present invention has focused on this, and has developed a short focus state for a long focus state T! ! Difference in the amount of movement of the focusing lens group at W (Lt-Lw
) is skillfully used in the range for opening and closing the lens cover, and the means for doing so is provided near the opening at the tip of the lens barrel, and the closing position that covers the opening and the A lens cover member that can be displaced to an exposed open position, and a movement amount of a focusing lens group at a focal length that allows the lens cover member to open and close,
The lens cover member includes a zoom optical system whose movement amount is smaller than that in a normal photographing state, and a focusing lens group driving member that adjusts focus by moving the focusing lens group forward and backward in the optical axis direction. Connecting the lens cover member and the focusing lens group drive member in a focal length state where opening and closing operations are possible, and driving the focusing lens group beyond the necessary focusing operation range in the focal length state, The present invention is characterized in that the lens cover member is placed in a closed state.

[Example] The present invention will be explained below with reference to illustrated embodiments.

FIG. 1 is a sectional view of the upper half of a zoom lens barrel in a short focus state W (wide state) showing a first embodiment of the present invention.

This zoom lens barrel consists of a fixed barrel 1 attached to a camera body (not shown), a cam barrel 2 rotatably and tightly fitted to the outer circumference of the fixed barrel 1, and an inner part of the fixed barrel 1. A movable member 83 tightly fitted around the circumference so as to move back and forth along the optical axis O, a lens cover unit 7 provided at the tip of the movable cylinder 3, and a lens cover unit 7 disposed within the movable cylinder 3. With an inner focus type zoom lens optical system,
The main parts thereof are covered by an exterior body 12 fixed by the camera body and the tip of the fixed barrel 1.

A cam cylinder 2 rotatably disposed on the outer periphery of the fixed cylinder 1 is connected to an outward flange 1a provided at the rear end of the fixed cylinder 1 and a circumferential groove 1b bored on the outer peripheral surface of the front end of the fixed cylinder 1. fitted C
Movement in the optical axis direction is regulated by a retaining ring 11 made of a ring, so that only rotation is possible, and the first lens group L1 and the third lens group L3 in the movable cylinder 3 are moved around the circumferential surface of the ring 11. An inclined cam slot 2a for moving the barrel 3 to the zoom position and an inclined cam slot 2b for moving the second focusing lens group L2 to the zoom position are provided.

An interlocking cam barrel 10 is integrally attached to the cam barrel 2 in the middle of its outer peripheral surface, and a zoom motor (not shown) is connected to a driving gear 10c provided on the outer periphery of the cam barrel 10. The driving force is transmitted and the cam cylinder 2 is rotationally driven. In addition, this interlocking cam cylinder 10
An end surface cam 10a is provided on the front end surface and rear end surface of the camera for moving a finder lens (not shown) during zooming.

10b is formed.

The movable cylinder 3 has a drive bin 8 on the outer peripheral surface near the rear end.
The pin 8 passes through a linear guide slot 1c in the optical axis direction drilled in the fixed barrel 1 and is fitted into the inclined cam slot 2a.

Further, a rectilinear slot 3a in the optical axis direction is bored in the rear part of this cylinder 3, and inside the slot 3a, the second group lens holding frame 5 has the same polarity, and the guide groove A driving pin 9 passes through the hole IC and fits into the inclined cam groove hole 2b.

The zoom lens optical system disposed inside the movable barrel 3 is located midway between the first lens group L1 supported by the first lens group holding frame 4 fixed near the front of the movable barrel 3. A second lens group L for focusing is movably supported by a second group lens holding frame 5 which is moved in the optical axis direction by the drive bin 9.
2 and a third lens group L3 supported by a third lens holding frame 6 fixed near the rear. Note that a shutter mechanism (not shown) is integrally attached to the second group lens holding frame 5. A lens cover unit 7, which will be described later, is integrally attached to the distal end of the moving frame 3.

Next, details of the focusing mechanism for focusing the second lens group L2 for focusing and the lens cover unit 7 will be explained with reference to FIG. 2. Note that this second
In the figure, only the portion of the focus mechanism related to driving the lens cover is depicted.

2nd group lens frame 5A supporting the 2nd lens group L2 for focusing
has a helicoid screw 5B carved on its outer peripheral surface, and a driving gear 50 is integrally provided at its rear end. The helicoid head 5B is the second group lens holding frame 5.
The second lens group L2 is disposed so as to be movable in the optical axis direction by being screwed into a helicoid screw 5a (see FIG. 1) formed on the inner circumferential surface of the second lens group L2. A transmission gear 13 is engaged with the driving gear 5C, and the rotational driving force of the AF MOMO-2M fixed to the lens holding frame 5 is transmitted to the transmission gear 13 via a gear train 14. There are 7 things like that.

Further, the driving force transmitted to the gear train 14 is transmitted to a cover drive ring 1 disposed near the drive gear 5C.
The transmission gear 16 also transmits the signal to the internal gear 15b of No. 5. This cover drive ring 15 rotates around the optical axis 0 when a driving force is transmitted, and a drive arm 15B that extends forward along the optical axis O is attached to a part of the cover drive ring 15. It is formed in one piece.

On the other hand, the lens cover unit 7 has an opening window 17 in the center.
a front cover 17 consisting of a disc having a shape and fixed to the inner circumferential surface of the distal end of the movable cylinder 3; and a pair of lens cover members 18 disposed overlappingly on the back surface of the front cover 17.
(only one is shown in the figure) and a cam ring 19 that drives the lens cover member] 8 to open and close.

The lens cover member 18 is formed of a pair of thin semicircular sector plates, and is configured to open and close the opening window 17a. That is, a support hole 18a is formed in the proximal end extension of the lens cover member 18, and by fitting the support hole 18a into the support pin 17b, which has the same polarity on the back surface of the front cover 17, the lens can be fixed. The cover member 18 is rotatably disposed on the back side of the opening window 17a of the front cover 17, and is driven by the cam ring 19 to close the opening window 17a.
It is designed to open and close.

The cam ring 19 is disposed immediately after the lens cover member 18 so as to be rotatable around the optical axis 0, and has a cam hole 20 for opening and closing the lens cover member 18 and a partially arc-shaped pin through hole 21. In addition, an engaging arm 19a that extends rearward and abuts against the drive arm 15a at appropriate times is integrally formed.

The cam hole 20 has a cam operating surface formed on the lower side of the opening. That is, as shown in FIG. 5, the left side of the lower side surface of the opening is an inclined cam surface 20a that slopes diagonally upward to the left, and the lower right side surface is a partially arcuate surface 20b centered on the optical axis O. It has become. As shown in FIG. 2, an opening/closing bin 22 having the same polarity as the back surface of the lens cover member 18 passes through the cam hole 20.
One end 23a of a torsion spring 23 is attached to the tip end of the torsion spring 23 for pressing the pin 22 against the cam operating surface. The torsion spring 23 is connected to the lens cover member 1.
8 and inserted through the pin through hole 21.
7b, the spring hook is wound around the central part thereof, has one end 23a mounted on the opening/closing bin 22, the other end 23b planted on the back surface of the front cover 17, and inserted through the pin through hole 21. ing. The opening/closing bottle 22 is always pressed against the inclined cam surface 20a or the partially arcuate surface 20b by the opening elasticity of one end 23a of the spring 23.

Further, the engaging arm 19a is connected to the first group lens holding frame 4.
It extends rearward through a partially arc-shaped insertion hole 4a bored therein, and its tip is located close to the drive arm 15a. In addition, this engagement arm 1
9a, as shown in FIG. 6A, there is a first group lens holding frame 4.
A compressible coil spring 25 is applied between the cam ring 19 and a spring hook 26 fixed to the cam ring 19, giving the cam ring 19 the habit of rotating clockwise γ around the optical axis O, as shown in FIG. ing. Therefore, when no load is applied to the engaging arm 1.9a, the cam ring 19 rotates clockwise γ to the position of the stopper 27 (see Fig. 6A) fixed to the first group lens holding frame 4. , the opening/closing pin 22 is pushed up by the inclined cam surface 20a to move the lens cover member 18 to the open position.

Next, to explain the operation of the zoom lens barrel configured in this way, first, when the optical system is further rotated from the close position in the wide-angle state (hereinafter referred to as the W-state), the closed lens cover Open the member 18 to open the opening window 17
To open a, the power is turned on, the AP motor M is started, the second focusing lens group L2 is moved to a close position, and the cover drive ring 15 is rotated clockwise γ.

Then, the drive arm 15a that was pushing the engaging arm 19a in the counterclockwise direction β also rotates in the clockwise direction γ.
The engagement arm 19a also rotates following this due to the tightening elasticity of the coil spring 25, and rotates the cam ring 19 around the optical axis O in the clockwise direction γ.

When this rotates, as shown by the dotted line in FIG.
is pushed upward by the inclined cam surface 20g as shown by the solid line. When this is pushed up, the lens cover member 18 shown in FIG. 2 rotates clockwise around the support pin 17b, thereby opening the opening window 17g.

Next, a zoom motor (not shown) drives the interlocking cam barrel 10 shown in FIG. 1 to perform a zooming operation. That is, when the interlocking cam barrel 10 rotates around the optical axis 0, the cam barrel 2 also rotates together, thereby opening the inclined cam slot 2a.

The drive pins 8 and 9 fitted in the lens 2b move the lens group L to the third lens group L3 back and forth in the optical axis direction by a predetermined amount of movement to perform zooming.

In the case of this embodiment, the movable cylinder 3
and the third lens group L3 move together.

FIG. 3 is a diagram showing the movement of each of the lens groups L1 to L3. As you can see from this figure, the lens group L and the third lens group L3 have changed from the W state to the telephoto state! !
(hereinafter referred to as T state). On the other hand, the second lens group L. Third lens group L1.
It will move in the same way, but behind L3. In this case, the lens group L and the second lens group L2 are closest to each other at the close position of the W state, and the second lens group L
and the third lens group L3 are closest to each other in the open position of the T state.

Then, after or before performing the zooming operation, a focusing operation is performed. This focusing operation is performed by driving the AF momo 2M shown in FIG. 2 and rotating the drive gear 5C via the gear train 14, thereby moving the second group lens frame 5A in the optical axis direction using the helicoid screw 5B. This is done by

The movement of the second group lens frame 5A is monitored by an encoder (not shown), and when it has moved an optimal amount based on the measured distance value, the AF MOMO-2M drive is stopped and the focusing operation is completed.

At this time, power is also transmitted from a part of the gear train 14 to the cover drive ring 15 via the transmission gear 16, and the drive ring 15 also rotates in conjunction with the rotation of the second group lens frame 5A. , it just floats around. Furthermore, when the second group lens frame 5A moves to the left in FIG.
The drive ring 15 is configured to rotate in the clockwise direction γ around the optical axis 0 when the drive ring 15 rotates to the right and moves to the right.

Thereafter, a shutter mechanism (not shown) is activated to adjust exposure, and the photographing is completed. After that, AF Momo-2M
It rotates in the opposite direction to return the second group lens frame 5A to the predetermined position (oo position). At this time as well, cover drive ring 1
5 rotates freely.

Next, the engagement M19 in the lens cover unit 7
6A and 6B, FIG. 6A shows the relationship between the drive arm 15a and the engaging arm 19a in the W state. It is.

During a normal focusing operation, the drive arm 15a rotates around the optical axis O by an angle θ0, as shown by the solid line, from the state of the second lens group L2 to the closest state shown by the dotted line, and performs the focusing operation. However, at this time, it does not engage with the engaging arm 19a of the cam ring 19. That is, in the W state, the drive arm 15a rotates at an angle θ0 in the focusing operation from infinity to close range, and does not collide with the engagement arm 19a, and furthermore, at the close position, the drive arm 15a still rotates at an angle θY.
The reason for providing this θY is that even if slight zooming (focal distance movement) is performed from the above-mentioned W state, the overlap between the drive arm 15a and the engagement arm 19a remains unchanged. There is no problem if Y is 0 or more, but if this is 0
If the angle is below, there is a risk that the drive arm 15a or the engagement arm 1.9a will be pushed, so the angle eY is determined taking this into account. Ideally, leave a gap between the two.

FIG. 6B shows a state in which the lens is further zoomed to the long focal point side, and the angle θ is 0 instead of 1 in FIG. 6A. At this time as well, it is necessary that the overlap dimension Y be greater than or equal to 0 as shown by Y'. In this way, when zooming is performed from the W state shown in FIG. 6A to the long focal point side, the stroke of the drive arm 15a from infinity to close distance increases compared to when it is in the W state, so the angle θYD becomes 0. become.

In this way, the drive arm 15a and the engagement arm 1.9a are
It does not engage during normal shooting operations. Therefore, in the photographing state, the lens cover 18 remains open.

Next, when the lens cover [8] is closed using the 20-shaped frame, the AF motor M is driven and the gear train 14. The cover drive ring 15 is rotated via the drive gear 5C and the transmission gear 16, and the drive arm 1 is rotated as shown in FIG. 6A.
5a is further rotated by an angle θ' from the close position. Then, in the range of this angle θ', the drive arm 15a collides with the engagement arm 19a and pushes it against the elasticity of the spring 25, so the drive arm 1.58 is at the position shown by the two-dot chain line. Then, the engaging arm J9a is moved to the cover closed position shown by the dotted line. Therefore, this causes the cam ring 19 to rotate and close the lens cover 18.

That is, since the cam ring 19 is rotated in the counterclockwise direction β (see FIG. 2) around the optical axis O by the engaging arm 19a,
The opening/closing pin 22 is connected to the cam hole 20 as shown by the dotted line in FIG.
is moved onto the partially arcuate surface 2Ob by the elasticity of the spring 23. When the opening/closing pin 22 moves, the lens cover 18 to which the opening/closing pin 22 is attached rotates counterclockwise around the support pin 17b, so that the opening window 17a of the front cover 17 is closed by the cover 18. In addition, in Figure 2,
As mentioned above, the lens cover 18. Cam hole 20. Although only one set of torsion springs 23, etc. are shown, in reality, another set is arranged at a symmetrical position with respect to the optical axis O, and the same operation is performed to open and close the aperture window 1.7a. .

In addition, when the lens cover 18 is in the closed state, the power is generally off when the camera is not in use, and the AF motor M is in the closed state.
Since the power supply to the lens cover 18 is stopped, the lens cover 18 is kept closed by the speed reduction mechanism of the gear train 14 and the self-holding torque of the motor M against the elasticity of the spring 25.

FIG. 4 shows the relationship between the amount of extension of the second lens group L2 and the focal length. In general, the amount of extension of the focusing lens group L2 of an inner focus type zoom lens changes depending on the focal length, and the amount of extension from ■ to close range (assuming 1 m) is greater in the T state than in the W state. There are more and more people. That is, as shown in Fig. 4, the characteristic of the extension amount depending on the focal length for focusing on a subject distance of 1 m is gl, and the characteristic of the extension amount depending on the focal length for focusing on a subject distance of Xm is gl. g, and the characteristic of the amount of extension to focus on the distance (■) depending on the focal length is goo.

Therefore, as mentioned above, the focusing mechanism is
Since it is configured to satisfy the maximum delivery amount (the delivery amount at close range) in the T state, there is a margin for the delivery amount in the W state. That is, the difference between the amount of extension at close range when the focal length is α and the amount of extension at close range in the W state is expressed as (Il). Here, the focal length α is the focal length state when it becomes Y or Y-O shown in FIG. 6A.

Further, the difference between the amount of extension at close range in the T state and the amount of extension at the focal length α is shown by (1). Therefore, the opening/closing operation of the lens cover according to the present invention may be performed using any of the arbitrary focal length states within the rectangular area ABCD in FIG. 4.

It should be noted that, if there is enough room for the focusing lens group itself to extend, it is of course possible to open and close it beyond the area of the mouth ABCD, or to open and close it in conjunction with the area of the mouth ABCD. be.

FIG. 7 is an enlarged view showing only the main part of the cam hole 2OA in the zoom lens barrel according to the second embodiment of the present invention.

In the first embodiment, the drive arm 15a and the cam ring 1
The engaging arm 19a of 9 is configured to be separated by an angle θ0 in the W state when the lens cover 18 is open, and the range of this separation distance is used as the focusing area in the W state. However, in this second embodiment, there is no separation distance between the drive arm 15a and the engagement arm 19a. Instead, as shown in FIG. 7, the inclined cam surface 20Aa of the cam hole 2OA formed in the cam ring 19A
An open cam portion 20Ac is provided continuously at the upper end portion of the opening cam portion 20Ac.

This opening cam portion 20Ac has an angle θ centered on the optical axis O.
0, and this angle θ0
Even if the cam ring 19A is rotated within the range of
Since the lens 8 remains stationary, the lens cover 18 maintains the open window 17a. Drive arm 1
5a and the engaging arm 19a are not separated from each other as described above even in the W state, so they rotate together around the optical axis O, and the drive arm 15a also rotates for focusing. Even if the engaging arm 19a rotates, the rotation angle at this time is θ0, so the lens cover 18 closes the opening window 17a as described above.
The system will remain open.

Next, the operation of closing the lens cover 18 from this W state will be described. The drive arm 15a can further rotate beyond the rotation angle θ0 for normal focusing operation. As explained in the first embodiment, this is because W
This configuration is used because the focus lens group is extended more in the T state than in the T state for the subject at the same position, and the rotation of the drive arm 15g beyond this angle θ0 is utilized. and close the lens cover 18. The structure 2 for closing the lens cover 18 is similar to that of the first embodiment, so its explanation will be omitted.

In addition, when the state is not W, the focal length α (see Figure 4)
Until now, the drive arm 15g and the engagement arm 19a rotated as a unit each time the focus was focused, but as described above, the cam ring 19
Due to the configuration of the cam hole 2OA of A, the lens cover 18 is maintained in the open state, and when the focal length α is closer to the T state, the driving arm 15a and the engaging arm 19a are moved in the direction of the optical axis O. Since the lens cover 18 is separated, even if the driving arm 15a rotates for focusing, the engaging arm 19a remains stationary, so the lens cover 18 remains open.

FIG. 8 shows a third embodiment of the present invention. The difference between this third embodiment and each of the above embodiments is that in the W state, as shown in FIG. 6A, a separation distance of an angle θ9 is formed between the drive arm 15g and the engagement arm 19a; When changing the lens cover closing mode from the W state, the second group lens holding frame 5 (see Figure 2) moves by an angle θ0 around the optical axis O, causing this separation distance to become O.
In this state, the lens operates to extend.

That is, as shown in FIG. 8, the second group lens holding frame 5 is placed at the base end of the linear guide slot IC (see FIG. 1) of the fixed barrel 1 at an angle of 000 around the optical axis O. A guide slot IA in a direction perpendicular to the optical axis O for rotation is provided in series. With this configuration, the drive pin 9 is inserted into the guide slot lA.
By guiding the drive arm 15a and the engagement arm 19a inward through the inclined cam slot 2b, the drive arm 15a and the engagement arm 19a rotate together, thereby closing the lens cover 18.

In the case of this third embodiment, the first. Unlike the case of the second embodiment, since the part beyond the normal focusing range in the W state is not used to close the lens cover, this range is used to configure the macro optical system in the W state. There is an effect that can be done.

Therefore, if this embodiment is used, the lens cover can be opened and closed efficiently not only for the inner focus type zoom lens assumed in the first and second embodiments but also for a zoom lens in which the amount of extension of the focusing lens is always constant. can do well.

In the above explanation, the lens cover is driven to open and close using the rotation of the cam ring, but the present invention is not limited to this, and the lens cover is driven to open and close by using a member that moves toward the central optical axis. It is also possible to drive the cover opening/closing mechanism.

[Effects of the Invention] As described above, according to the present invention, basically, in an inner focus type zoom lens, attention is paid to the fact that the amount of movement of the focusing lens in the Wtk state is smaller than that in the T state. Since the lens cover is closed using the difference in drive amount, a remarkable effect is obtained in that there is no need for special extra space in the focus lens movement area, unlike in conventional models. In addition, if the lens cover drive member and the focusing lens holding frame can be connected by a zooming mechanism, the amount of movement of the focusing lens in the W state can be driven beyond the normal range, making it easier to use a macro optical system. Furthermore, since the zooming operation only involves the connection of the lens cover drive member and the focusing mechanism, there are fewer extra cams compared to conventional systems in which the opening and closing of the lens cover is linked only with the zooming operation. Therefore, the strength of the cam and the degree of freedom in designing the cam are advantageous.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the upper part of a zoom lens barrel in the W state showing a first embodiment of the present invention, and FIG. 2 shows details of the focus mechanism and lens cover unit in FIG. 1 above. An exploded perspective view, FIG. 3 is a line diagram showing the movement of each lens group in the zoom lens barrel of FIG. 1, and FIG. 4 is a line diagram showing the relationship between the extension amount and focal length of the second lens group L2. 5 is an enlarged front view of the cam hole formed in the cam ring in FIG. 1, and FIGS. 6A and 6B are the relationship between the engaging arm in the lens cover unit and the drive arm in the focus mechanism. FIG. 7 is an enlarged front view of a cam hole in a zoom lens barrel showing essential parts of a second embodiment of the present invention, and FIG. 8 is an enlarged front view of a main part of a third embodiment of the present invention. FIG. 3 is an enlarged plan view of a guide slot and an inclined cam slot in the zoom lens barrel. 17a... Opening window (opening) 18... Lens cover member

Claims (1)

[Claims] (1) A lens cover member provided near the opening at the tip of the lens barrel and movable between a closed position that covers the opening and an open position that exposes the opening, and an opening/closing operation of the lens cover member. A zoom optical system in which the amount of movement of the focusing lens group at a possible focal length is smaller than the amount of movement in normal shooting conditions, and a focusing lens group drive that adjusts the focus by moving the focusing lens group back and forth in the optical axis direction. a member, which connects the lens cover member and the focusing lens group driving member at least in a focal length state in which opening and closing operations of the lens cover member are possible, and performs necessary focusing operations in the focal length state. A zoom lens barrel characterized in that a focusing lens group is driven beyond a range to bring the lens cover member into a closed state.