JPH026915A - Lens barrel - Google Patents

Abstract

PURPOSE:To prevent deterioration in optical performance due to the play between a moving member and a fixed member by providing a means which energizes a compensator frame in one direction parallel to an optical axis. CONSTITUTION:When the compensator frame 15 is energized in one direction parallel to the optical axis and cam followers 17a and 17b united with the compensator frame 15 are held pressed against one flank of the cam groove 10b of the cam ring 10; and the play between the cam followers 17a and 17b and cam groove 10b is eliminated and the cam ring 10 is pressed in the energizing direction to eliminate the play of the cam ring 10 in the optical-axis direction. Consequently, the fixed cylinder 6 is made of plastic, deterioration in optical performance due to the play is eliminated, the zoom lens is reduced in size and improved in productivity, and the cost reduction is accelerated.

Description

[Detailed description of the invention]

[Industrial Use Lamp] The present invention relates to a lens barrel of a misalignment lens suitable for use in video cameras and the like. [Prior Art] A zoom lens has a complex structure, consisting of a focusing mechanism, a zooming mechanism, and an imaging mechanism. There has been a tendency for lens barrels themselves to become larger and heavier. −
・Nowadays, video cameras tend to become smaller and more compact, and with this trend, the zoom lenses used for these cameras are becoming smaller, lighter, and even more compact (1J). Simplification and cost reduction are desired.As a measure to meet these demands, parts that were conventionally turned metal are made into plastic moldings to reduce weight and integrate multiple parts. However, with plastic molded products, it is difficult to obtain uniform and stable dimensional accuracy like with metal turning, and dimensional changes due to temperature changes are difficult to obtain. The amount is also generally larger than that of metal mills.For this reason, when using plastic moldings, it is necessary to consider the following five points.Firstly, when using plastic moldings for the moving mechanism, the necessary It is necessary to have at least a clearance (backlash) between the movable part and the fixed part.In order to maintain this clearance with high accuracy at all times, it is necessary to increase the precision of the parts or restrict the clearance in one direction. Second, when the movable member and the fixed member are made of different materials, it is necessary to set the clearance by taking into account the difference in the amount of dimensional change due to temperature change. If 9. is a plus deck molded body and the other part is a turned metal piece, it is necessary to make the clearance larger than when these parts are made of the same material. However, even considering the following points, 1. If the clearance is increased, performance problems will occur.For example, in the zoom mechanism of the Zoom 1 Men's, the play between the movable member and the fixed member increases, causing the image to stop or become blurred during zoom operation. As an example of a method for stabilizing the zoom operation of the zoom mechanism, in the conventional example described in Japanese Utility Model Application Publication No. 53-60824, a fixed barrel is By biasing the rotatably held cam ring in one direction along the optical axis with respect to the base of the fixed cylinder, the backlash of the cam ring in the optical axis direction is suppressed. This pressing means has a structure in which the end surface of the cam cylinder is pressed by an elastic member through a plurality of balls. ]: Problems to be solved by the invention Although this is effective, play also occurs in the radial direction (circumferential direction), and as a result, even if the cam ring moves in the radial direction,
The problem is that optical performance deteriorates. This problem will be explained below with reference to FIG. 14, which schematically shows the deviation 15 generally used in a conventional zoom lens. In the figure, 7] is a variator lens group that performs a magnification change function during zooming, 72 is a conopensator lens that corrects the deviation of the imaging plane caused by the variator, 73 is a variator frame that holds the variator lens, 74 is a compensator frame that holds a compensator lens, 75a is a cam follower attached to the variator frame 73, and 751) is a cam follower 76a and 76b attached to the compensator frame 74, respectively. A cam follower 75a, 77, guides the movement of the variator frame 74 in the optical axis direction.
A cam ring having two spiral cam grooves (not shown) into which the cam rings 75b are respectively fitted, 78 a fixed cylinder that encloses the cam ring 77 and rotatably holds it therein, and 79 a long door 6a. '76b, the presser plate 80 that presses the cam ring 77 is a zoom ring connected to the cam ring 77 and rotatably attached to the fixed cylinder 78. In the zoom lens having such a configuration, when the zoom ring 80 is rotated, the cam ring 77 coupled to the zoom ring 80 is rotated. This cam ring 77 is provided with two spiral cam grooves, into which cam followers 75a and 75b are fitted, respectively. Therefore, as the cam ring 77 rotates, the cam followers 75a and 75b are guided by the cam grooves, and the cam rings 77 rotate.
6b in the optical axis direction. These cam followers 75a. 75b is a convencator frame 74 holding each compensator lens 72. Since it is attached to the variator frame 73 that holds the variator lens group 71, as the cam followers 75b and 75a move, the variator lens group 72. The variator lens group 71 includes rods 76b and 76a.
A zoom operation is possible by moving in the optical axis direction while being guided by 0 or more. By the way, in order to perform the above operation, it is naturally necessary to provide a clearance between the moving part and the rotating part. However, such clearance causes play between these members, which causes variator lens group 71. This causes a deviation from the design value for the compensator lens 72 in the optical axis direction, causing problems in the optical performance of the zoom lens. There are primary parts where such backlash occurs. (1) Play between the cam followers 75a, 75b and the cam groove of the cam ring 77. (2) The length of the cam ring 77 and the fixed cylinder 78. Backlash due to the difference between the dimensions of the entry part of the cam ring 77 due to the presser plate 79 (3) Backlash due to the difference between the inner diameter of the fixed cylinder 78 and the outer diameter of the cam ring 77 Although consideration was given to the deviation in the optical axis direction, the above (1) and (
Item 3) has not been taken into account, and therefore there has been a problem in terms of optical performance deterioration due to deviations in the optical axis direction due to these items. SUMMARY OF THE INVENTION An object of the present invention is to provide a lens barrel that eliminates such problems and prevents deterioration of optical performance due to backlash between a moving member and a fixed member. [Means for Solving the Problems] In order to achieve the above object, one aspect of the present invention provides means for biasing the compensator frame in one direction parallel to the optical axis. Further, in the present invention, the shape of the cam groove into which the cam follower integrated with the compensator frame is fitted is a linear shape that is inclined at a predetermined angle or less with respect to a straight line perpendicular to the optical axis on the telephoto side. This angle is set to 30 degrees or less so that the amount of movement of the compensator lens in the optical axis direction is smaller than the amount of rotation of the cam ring. Furthermore, the present invention provides an elastic member between the fixed cylinder and the cam ring. [Operation When the compensator frame is biased in one direction parallel to the optical axis,
The cam follower integrated with this compensator frame is in a state where it pushes one side of the cam groove in the cam ring,
There is no play between the cam follower and the cam groove, and the cam ring is pushed in the urging direction, so that no play is caused in the optical axis direction of the cam ring. When a radial play occurs in the cam ring, depending on the direction, the cam ring becomes rotated relative to the cam follower. For this reason, the cam follower may be displaced in the optical axis direction due to play in the radial direction of the cam ring. on the other hand,
The greater the angle at which the cam groove is inclined with respect to the straight line perpendicular to the optical axis, the greater the amount of displacement of the cam follower in the optical axis direction relative to the amount of rotation of the cam ring. In particular, on the telephoto side of the compensator, the depth of field is shallow, so even a slight shift in the cam follower will have an effect. Therefore, by making the shape of the cam groove on the compensator side a straight line that is inclined at a predetermined angle or less with respect to a straight line perpendicular to the optical axis on the telephoto side, the radial backlash of the cam ring can cause the cam follower's optical axis direction to change. The displacement can be kept within the depth of field even on the telephoto side, thereby eliminating the influence of this backlash. For example, if an elastic member is installed between the base of a fixed part such as a fixed cylinder or a holding plate and the cam ring, the returning force of the elastic member will cause the cam ring to move 1 m in one direction (= J force and play). By providing this elastic member between the fixed cylinder and the cam ring, the position of the cam ring with respect to the fixed cylinder is fixed,
The central axis of rotation of the cam ring is fixed, and play in the radial direction can be eliminated. Moreover, when the elastic member is provided between the presser plate and the cam ring, the cam ring is biased in one direction parallel to the optical axis, and play in the optical axis direction can be eliminated. [Example] Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a partial sectional view showing an embodiment of a lens barrel according to the present invention, in which 1 is a front lens holder, 2 is a front lens group,
3 is a spacing ring, and 4 is a focus ring. 5 is a helifit screw. , 6 is a fixed cylinder, 7 is a cam gear ring,
8 is a connecting tube, 9 is a presser plate, 10 is a cam ring, and 11a. 11b is a rod, ]-2 is a variator lens group, 13 is a variator frame, ]4 is a compensator lens, ]-5
is a compensator frame, ]-6 is a compression spring, and 17a. 1, 71) is a cam follower, 18 is a zoom ring, 19 is a zoom motor, 20 is a zoom gear, 21 is a relay gear, 2
2 is an inner master cylinder, and 23 is an outer master cylinder. In the figure, a front lens holder 1 has a front lens group 2 and other lenses mounted at predetermined intervals through spacing rings 3. The front lens holder 1 is fixedly provided inside the focus ring 4. Further, a helicoid screw 5 is provided on the inner surface of the focus ring 4, and a helicoid screw provided on the outer surface of the fixed barrel 6 meshes with this helicoid screw. Furthermore, a cam gear ring 7 for autofocusing is provided on the outer surface of the focus ring 4. The above is the configuration of the front lens part, and with this configuration, when the focus g4 is rotated, the focus ring 4 is rotated with respect to the fixed barrel 6 and moved in the optical axis direction by the helicoid screw 5, and the focusing operation is performed. Do it t15. Next, 1J, the zoom section will be explained. The fixed cylinder 6 has a bottom portion on the joint cylinder 8 side, and a presser plate 9 is fixed to the end face on the front lens side. Inside the fixed cylinder 6, a cam ring 0 whose length is almost equal to the length of the fixed cylinder 6 is provided so as to be rotatable with respect to the fixed cylinder 6.
The rods lla and l are connected by the bottom of the fixed cylinder 6 and the presser plate 9.
lb is supported parallel to the optical axis. [Rod] 1-a is slidably attached to the Balini evening frame J3 holding the variator lens group 12, and the rod 1-1b is
A compensator frame 15 holding a compensator lens 14 is slidably attached. Furthermore, a compression spring] 6 is provided between the presser foot @9 and the convencator frame 15 on this rod llb. The cam ring 10 is provided with two spiral cam grooves (not shown), each of which has a cam follower 17a, 1 attached to the variator frame 13 and convencator frame 15.
7b is fitted. A zoom ring 18 is provided on the outside of the fixed barrel 6 so as to be rotatable with respect to the fixed barrel 6, and is connected to the cam ring 1o through a through groove (not shown) provided in the fixed barrel 6. In the above configuration, when the zoom ring 18 is rotated, the cam ring ]0 is also rotated, and the cam follower 17a is guided by the spiral cam groove provided in the cam ring IO. The position of 17b changes. As a result, variator frame 1
3. Each convencator frame 15 is a rod 11a. 11b to move in the optical axis direction to obtain the specified zoom magnification. The position of the convencator lens 14 is adjusted. The zoom magnification can be set manually by the user by manually rotating the zoom ring 8, or automatically by immediate movement of the zoom motor 19. A zoom gear 20 is fixed to the rotating shaft of the zoom motor 9, and this gear 20 meshes with a relay gear 2 that meshes with a gear (not shown) provided on a zoom ring 18. In addition,
An iris and the like are also fixed to the joint tube 8. Next, the mask section will be explained. In the mask portion, an inner master cylinder 22 that holds a master lens group and whose position can be adjusted in the optical axis direction is enclosed in an outer master cylinder 23. The above is an explanation of the configuration and basic operation of this embodiment.
We will explain the means to eliminate the problems caused by using plastic. In the cam ring 10, it is necessary to machine the shape of the cam groove with a high precision of about 5 to 12 μm, and for this reason, the cam ring 10 is currently made of metal such as aluminum. On the other hand, if the fixed cylinder is made of plastic, one problem will be due to the difference in expansion rate between the fixed cylinder 6 and the cam ring 10.
The cam ring 10 may become unable to rotate due to thermal expansion. That is, when the operating temperature is between 110°C and 50°C, 1
It is necessary to provide a play that allows the cam ring 10 to rotate even if the ambient salinity is 110'C. The amount of play is at least 10
There is no performance problem at ~15 μm, but if you set this amount of play at low temperatures, the amount of play at high temperatures will be 3 times the length of the cam ring 10.
If it is 0 wm, it will be 50 to 70 μm, and the cam ring 10 will wobble greatly in the optical axis direction, which will cause a performance problem. In order to solve this problem, in this embodiment, a compression spring 16 is provided between the Rondo LLB upper presser plate 9 and the compensator frame 15.
This will be explained using figures. However, FIG. 2 is a cross-sectional view showing such a configuration, and 6a. 9a is a rod hole, 10b is a cam groove, 24 is a screw,
Parts corresponding to those in FIG. 1 are given the same reference numerals. In the figure, one end of the rondo Ilb is inserted into a rod hole 6a provided at the bottom of the fixed cylinder 6, and the other end is inserted into a rod hole 9a of the holding plate 9. This presser plate 9 is fixed to the fixed cylinder 6 with screws 24. A compensator frame 15 is slidably attached to the Rondo LLB.
A coil-shaped compression spring 16 is provided between the presser plate 9 and the compensator frame 15. This compression spring 16 is such that the compensator frame 15 is connected to the rod l.
Regardless of the position on the lb, the compensator frame 15 is in a compressed state, so that the compensator frame 15 is always urged toward the bottom side of the fixed cylinder 6. For this purpose, the cam follower 17b provided in the compensator frame 15 presses the bottom side end surface of the fixed cylinder 6 in the cam groove 10b of the cam ring 10,
As a result, the cam ring 10 is urged toward the bottom side of the fixed cylinder 6 by the cam follower 17b. The biasing force of the compression spring 16 removes the backlash of the cam ring 10 in the optical axis direction and the play between the cam groove 10b of the cam ring 10 and the cam follower 17b. In the above manner, backlash in the optical axis direction is removed. Regarding play between the cam follower 17a provided in the variator frame 13 and the cam groove of the cam ring 1o, it is difficult to use the above method. This is because the amount of movement of the variator frame 13 is large, so designing the compression spring is extremely difficult. However, this backlash can be eliminated by configuring a cam follower 17a as shown in FIG. 3, for example. That is, this method allows the cam follower 17a to be elastically deformed. In Figure 3, cam follower 1
7a is made into a thin-walled shape using a plastic material, and the cam groove 1 is
The cam groove 10a is elastically deformed within the cam groove 10a so that there is no clearance between the cam groove 10a and the cam groove 10a. However, since the positions of the variator lens group and the compensator lens are regulated by the cam groove, a problem arises even if an error occurs in the position of the cam follower that fits into the cam groove. Therefore, in order to eliminate this problem, the position of the cam follower is regulated as follows with respect to the lens position in the compensator frame (or variator frame). In FIG. 3(b), in order to secure the position of the cam follower 17b with reference to the point P of the lens contact surface of the compensator frame 15, the cam follower part that enters the compensator frame 15 is positioned from the point P and is fitted. I have to. That is, a fitting hole is provided in the compensator frame 15, and a portion that fits into the fitting hole is provided at the bottom of the cam follower 17b. Regarding the variator frame 13, as shown in FIG. 3(a), the position of the cam follower 17a is set in the same manner as on the compensator frame 15 side, using the point Q of the contact surface of the variator lens group to the variator frame 13 as a reference. , so that it can be secured. In FIG. 1, the compression spring 16 is inserted between the holding plate 9 and the convencator frame 15, but even if it is inserted between the bottom of the fixed cylinder 6 and the convencator frame 5, the convencator The biasing direction of frame 15, ka, ring] 0 will change.

[
A similar effect can be obtained with Next, the radius of the cam ring JO, which is 10 times larger than this example. We will now discuss the means for eliminating the problem 7) caused by backlash in the direction 1). As mentioned above, the radial direction of the fixed cylinder 6 and the cam ring 10 is also
Considering the amount of dimensional change due to temperature change, at low temperature], 5
It is necessary to ensure a clearance of about μm. If this is done, the backlash at high temperatures will increase by 5, similar to the backlash in the optical axis direction, resulting in two problems with optical performance. Especially on the telephoto side. , since the depth of field becomes shallow, the influence of this backlash becomes significant. Fig. 4 shows the cam follower 1'/with the radial play of the cam ring] 6 in the direction of arrow A (that is, the variator frame) 3''/
This is a diagram for explaining the problem that occurs when the problem occurs in the direction of the straight line connecting the optical axis and the optical axis. The position of the cam ring 10 before it moves is also shown, and the lower right re-hatching part surrounded by a solid line shows the position of the cam ring 10 after it has moved due to this play. Suppose that the claw moves by p in the direction of the arrow. If Bi is the point on the J2 part of the cam groove 10a into which the cam follower 1.7a is fitted before this movement, then the movement of the cam ring 10 due to this backlash causes 7. The second point B□ also moves in the direction of the arrow and becomes point B1'. Since this direction of movement is parallel to the side surfaces of the cam followers 1 and 7a, the cam follower t7a is not affected at all. Further, it is assumed that the cam follower 17b is at the position shown by the solid line due to the two cam grooves Job before the cam ring 1o moves in the direction of the arrow A. At this time, the upper point of cam 5iob is B2
Then, as the cam ring 10 moves in the direction of the arrow, this point B2 also moves in the direction of the arrow to become point B2. Since the direction of the arrow is not parallel to the straight line connecting the cam groove 1, Ob and the optical axis, in the end, regarding the cam follower 1.7b, the cam ring 10 rotated counterclockwise around the optical axis. The throat becomes equal. Here, the positional relationship between the rod llb and the cam follower 17b in the circumferential direction around the rod 1.1b is fixed. If not, it would be 1 point B, but it would be point B.
, and the cam follower 17b will rotate around the rod llb indicated by the broken line, but if the positional relationship shown in the figure is fixed, the cam groove 10b
Even if point B2 moves to point Bz' and cam ring 1-0 equivalently rotates counterclockwise, the cam follower ],
7b must be in the state shown by the solid line, and for this purpose, the cam ring]0 has moved in the direction of the arrow, and the cam follower 17b corresponds to the point B2' of the cam groove 1, Ob. It must be located at a position in the cam groove 10b such that the point on the side is the contact point D2 of the cam follower 17b. That is, the cam follower 17b must be located at a different point D2 in the cam groove 10b, such as point B2', and therefore, the cam follower 17b has moved in the optical axis direction along the rod Ilb. That is, before the cam ring 10 moves due to backlash, the distance between the cam rings 1o of the two cam followers 17a and 17b in the drawing is B.
1・B, but when the cam ring 1° moves in the direction due to play, the interval becomes B11・D2 (≠B1
・'p'! ), and the cam follower 71) moves along the rod ]-b. This can be further explained using the developed view of the cam ring shown in Figure 5.
Before movement due to play of the cam ring 10, the cam follower 17a,
The position of 17h in the optical axis direction is cl. In the case of C2 and 12, by the movement of the cam ring] 0, the cam follower 17b moves in the optical axis direction by ΔQ so that the position in contact with the cam groove 10b of the cam follower 17b moves from point B to the point The position in the direction is 02'. When the cam ring 1o moves due to play in the radial direction in this manner, the cam follower 17b moves by ΔQ in the optical axis direction. It can be seen that this movement amount ΔQ increases as the angle θ between the cam groove 10b and a line perpendicular to the optical axis increases. Furthermore, when the cam ring 10 moves with radial play in the direction connecting the cam follower 17b of the compensator frame 15 and the optical axis, the cam follower 17a of the variator frame 13 moves in the optical axis direction. The amount of movement of the image position on the imaging plane relative to the amount of movement of these cam followers in the optical axis direction is generally larger for the compensator than for the variator. Therefore, in this embodiment. As shown in FIG. 6, the cam groove 10 for the compensator
The shape of b is a straight line inclined by 30° or less, for example 25°, with respect to a straight line perpendicular to the optical axis near the telephoto end. This straight line portion is a portion where the imaging plane movement is sensitive to the amount of movement of the compensator in the optical axis direction due to the radial backlash of the cam ring 1o. Here, it was set to about 18, which is the entire zoom range. This is because if it exceeds this, the depth of field becomes deep and movement errors in the optical axis direction become ineffective. After determining the shape of the cam groove 10b on the compensator side in this way, the shape of the cam groove 10a on the variator side is determined. For this reason, the zoom magnification does not change uniformly as the cam ring 10 rotates, but if the straight portion is inclined at about 25', no discomfort will occur. The seventh example shows an example in which the slope of the straight portion of the cam groove 10a is further reduced.
In this specific example shown in the figure, the imaging plane movement sensitivity is small, but the shape of the cam groove 10b on the compensator side has undulations, so the cutter does not move smoothly when machining the cam groove 10b. Therefore, the example shown in FIG. 6 is more advantageous in terms of processing. As described above, by reducing the inclination angle of the cam groove 10b on the compensator side of the cam ring 10 with respect to the line perpendicular to the optical axis on the telephoto side, the compensator lens 14 that is caused by the radial backlash of the cam ring 10 can be reduced. Displacement in the optical axis direction can be made small, and the amount of movement of the imaging plane can be made so that there is no problem in practical use. Therefore, the fixed tube 6 can be made of plastic. FIG. 8 is a cross-sectional view of main parts showing another embodiment of the lens barrel according to the present invention, in which 25 is a space, 26 is a notch, and 27
2 is an elastic ring, 28 is a protrusion, and parts corresponding to those in FIG. 1 are given the same reference numerals. In this embodiment, a means for removing radial backlash is provided in the cam ring. In the figure, a slight space 25 is provided between the fixed cylinder 6 and the presser plate 9, and an elastic ring 27 is disposed within this space 25 to remove radial play of the cam ring 10. There is. As shown in FIG. 9, the elastic ring 27 has a plurality of through grooves 29a to 29 along the ring.
9e are provided, and these through grooves 2 are provided on the outer peripheral surface of the ring.
One protrusion 28 is provided on the inner peripheral surface of the protrusions 30a to 30e and the ring thereof, facing each of the protrusions 9a to 29e. As shown in FIG. 10, a cutout 26 is provided on the end surface of the cam ring 10 on the side of the presser plate 9, and by fitting the protrusion 28 of the elastic ring 27 into the cutout 26, the elastic ring 27 can be removed. It is attached to the cam ring 10. When the elastic ring 27 is attached to the cam ring 10,
The inner peripheral surface of the elastic ring 27 contacts the outer peripheral surface of the cam ring 10, and the projections 30a to 30e of the elastic ring 27 contact the inner peripheral surface of the fixed cylinder 6 in the space 25, respectively. At this time, the elastic ring 27 is inserted into the through groove 29a so that the protrusions 30a to 30e are pressed against the inner peripheral surface of the fixed cylinder 6.
It is elastically deformed by ~29e. In this way, the elastic ring 27 allows the cam ring 1o to
is held within the fixed cylinder 6, and the radial play of the cam ring 10 is absorbed. Therefore, deterioration in optical performance due to radial backlash can be eliminated. FIG. 11 is a cross-sectional view of main parts showing still another embodiment of the lens barrel according to the present invention, in which 32b is a protrusion, 33 is a step, and 34 is a mounting portion, which corresponds to FIG. are given the same symbol. In this embodiment, the cam ring 10 is provided with means for removing backlash in the optical axis direction and radial play. 1: In the same way as in the embodiment shown in FIG. Ring 10
An elastic ring 27 is attached to the tip of the cam ring 1.0 on the side of the holding plate 9, and this elastic ring 27 eliminates play in the optical axis direction and radial play of the cam ring 1.0. That is, the elastic ring 27 has most of the same configuration as the elastic ring 27 shown in FIG. 9, but as shown in FIG.
a to 29e (however, through groove 29c=29e is not shown)
Through grooves 31a to 31e (however, through grooves 31c and 31e reach
-31e (not shown) is provided on the side surface of the inner peripheral side of the through groove 29a''29e.The through groove 131a
-31c, a protrusion 32a''32e (however, the protrusion 32e-32e are not shown) is crotched.On the other hand, at the tip of the cam ring 10, as shown in Figs. A mounting portion 34 having a smaller diameter than the portion where the cam groove 10a is provided is provided, and the boundary between this mounting portion 34 and the portion where the cam groove 10a is provided forms a stepped portion 33.This mounting portion 3
A notch 26 is provided on the end surface of 4. The elastic ring 27 is attached to the mounting portion 34 of the cam ring 10 by fitting its protrusion 28 into the notch 26 of the cam ring 10.
can be attached to. At this time, the inner circumferential surface of the elastic ring 27 comes into contact with the mounting portion 34 of the cam ring ]-0, and the protrusions 30a to 30e on the outer circumferential surface contact the inner circumferential surface of the fixed cylinder 6 in the space 25 as shown in FIG. Similar to the embodiment shown, it is pressed together. As a result, the radial play of the cam ring 10 is removed, and the elastic ring 27 is
It is attached to the cam ring 10 so that the side surface opposite to the side where the cam ring 32e is provided comes into contact with the stepped portion 33 of the cam ring 10. Then, as shown, attach the elastic ring 27 to the cam ring 10.
Attach and attach it to the holding plate 9F and screw it to the fixing cylinder 6.
The inner peripheral side of the elastic ring 27 than the through grooves 31a and 31e is pushed into the presser plate 9 and the stepped portion 33 of the cam ring 10, so that the through groove 31a=:3
The protrusions 32a to 32e are elastically deformed by 1e and pressed against the holding plate 9 6, and the cam ring 1.0 is urged toward the bottom side of the fixed cylinder 6 by the restoring force caused by the deformation of the elastic ring 27. This eliminates backlash of the cam ring 10 in the optical axis direction. In the embodiments shown in FIGS. 8 to 13, the play between the cam follower and the cam groove can be eliminated by using the means shown in FIG. 1.0 In the embodiment shown in Figure 1, similarly, the cam ring 1
It is also possible to eliminate backlash in the direction of the optical axis. [Moving bed of the invention] As explained above, according to the present invention, optical performance is improved not only due to play in the optical axis direction of the cam ring, but also due to play in the radial direction and play between the cam groove and the cam follower. Even if the fixed tube is made of plastic, it is possible to prevent the optical performance from deteriorating due to these backlashes.
Zoom 1 can promote weight reduction, productivity improvement, and cost reduction.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing an embodiment of the lens barrel according to the present invention, FIG. 2 is a sectional view showing a part of the zoom section in FIG. 1, and FIG. - A sectional view showing a specific example of a cam follower installed in the evening frame and its position regulation, Figure 3(b) is the compensator frame 1. 4 is an explanatory diagram of the play in the radial direction of the cam ring, FIG. 5 is a diagram showing the displacement of the cam follower in the optical axis direction due to this play, and FIGS. FIG. 7 is a diagram showing a specific example of a means for reducing the amount of displacement of a forceful follower due to play in the radial direction of the cam ring, and FIG. 8 is another embodiment of the lens barrel according to the present invention. FIG. 9 is a perspective view showing a specific example of the elastic ring in FIG. 8, FIG. A perspective view, FIG. 11 is a main part sectional view showing another embodiment of the l-nons lens barrel according to the present invention, and FIG. 12 is a partial perspective view showing a specific example of the elastic ring in FIG. 11. , FIG. 13 is a partial perspective view showing the structure of the tip of the cam ring in FIG. 11, and FIG. 14 is a partial sectional view showing an example of a conventional lens barrel. 2...Front lens group, 6...Fixed barrel,
9... Pressing plate, 10... Cam ring, 10
a, 10b...cam groove, lla, llb...
...rod, 12...variator lens group,
13... Variator frame, 14... Compensator lens, 15... Compensator frame, 16... Compression spring, 17a, 17b...
...Cam follower, 26...Notch, 27...
...Elastic body ring, 28...Protrusion, 29a
~29e...through groove, 30a~30a...
・Protrusion, 31a, 31b... Through groove, 32
a, 32b...protrusion, 33...step, 34...attachment part. 3rd factor Figure 2 Figure 3 Figure 5 Figure 6 Figure 9 Figure io Figure '// Figure 7° Figure 8 Figure 12 Figure 13 Figure 741? I

Claims (1)

[Scope of Claims] A cam ring having first and second cam grooves and rotatable inside a fixed cylinder; a zoom ring for rotating the cam ring;
A variator frame that holds a variator lens group and is movable in the optical axis direction along a first rod, a compensator frame that holds a compensator lens and is movable in the optical axis direction along a second rod, and the variator frame. fixed to the first
a first cam follower fitted into the cam groove; a second cam follower fixed to the compensator frame and fitted into the second cam groove; and a second cam follower fixed to the fixed cylinder and supporting the first and second rods. In a lens barrel having a zoom portion consisting of a presser plate, a means for biasing the compensator frame in one direction parallel to the optical axis is provided, the fixed barrel is made of a plastic molded body, and the cam ring is made of a metal material. A lens barrel characterized by the following. 2. The lens barrel according to claim 1, wherein the shape of the second cam groove on the telephoto side is a straight line inclined at a predetermined angle or less with respect to a straight line perpendicular to the optical axis. 3. In claim 2, the first
, a lens barrel characterized in that the shape of the second cam groove is set. 4. In claim 2 or 3, the predetermined angle is 30°.
A lens barrel characterized by: 5. According to claim 2, 3 or 4, the position of the variator lens group can be set so as to obtain a desired zoom performance with respect to the position of the compensator lens according to the shape of the second cam groove, A lens barrel characterized in that the shape of the first cam groove is set. 6. The lens barrel according to claim 1, further comprising an elastic member provided between the cam ring and the fixed member. 7. In claim 6, the elastic member has a ring shape and is fixed to the cam ring, and is elastically deformed so that a part of the outer peripheral surface of the elastic member is pressed against the inner peripheral surface of the fixed cylinder. . A lens barrel, characterized in that the rotation center axis of the cam ring is fixed. 8. The lens barrel according to claim 6 or 7, wherein the elastic member urges the cam ring in one direction parallel to the optical axis.