JPS59214813A - Four-group type zoom lens barrel - Google Patents

Abstract

PURPOSE:To improve the positioning precision of a relay lens group by positioning and adjusting a focal point by the optical-axis movement of a compensating lens group. CONSTITUTION:An eccentric pin 37 has a screw part 37 eccentrically with a head part 37a, and the screw part 37b engages the screw hole 36a of a holding frame 36 threadably to allow the head part 37a to rotate. The head part 37a is fitted in a specifying long hole 35c bored in a cam frame 35 in a circumferential direction. When the focal point is positioned and adjusted, the eccentric pin 37 is rotated to displace the head part 37a to or from the screw part 37b. The head part 37a is displaced to or from the cam frame 35 in optical-axis directions while a support frame 36 is guided by a guide long hole 5b and a guide pin 38. The rotation of the eccentric pin 37 is stopped once the focal point is positioned at a specified position over a look at a collimator. The position relation between a variable power lens group II and the compensating lens group III is determined unequivocally and the focal point is positioned and adjusted accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a four-group zoom lens barrel, and more particularly to a mechanically compensated four-group zoom lens barrel that allows easy positioning and adjustment of the focal position. .

As is well known, the mechanically compensated 4# zoom lens barrel has a focus lens group.

4 variable magnification lens groups, compensation lens groups, and relay lens groups
Two lens groups are sequentially arranged, and the variable power lens group and the compensation lens group are moved by a cam mechanism in the direction of the original axis while satisfying a predetermined relationship, thereby performing a zooming operation.

FIG. 1 shows an example of a conventional four-group zoom lens barrel. This zoom lens barrel includes four lens groups: the focus lens group (2), the variable power lens group I, the compensation lens group (3), and the relay lens group N, the focus lens group I, the variable power lens group 1, and the compensation lens group. Focus lens frame 1 that holds lens group I and relay lens group ■, respectively. Variable power lens frame 2. ! Redemption lens frame 3 and relay lens frame 4
a mount member 5 attached to the camera body (not shown); a support frame 6 fixed to the mount member 5 and into which the relay lens frame 4 is fitted inside; The rear end portion is fixed, and the compensation/aperture frame 3 is rotatably disposed on the inner side of the center, and the aperture value is set for the aperture mechanism (not shown). An aperture ring 8, a zoom operating frame 9 slidably and rotatably fitted to the middle outer periphery of the fixed frame 7, and an inner periphery of the rear end fixed to the outer periphery of the rear end of the zoom operating frame 9. A distance adjustment ring 11 is rotatably integrated with the focus lens frame 1, and a distance adjustment ring 11 is installed on the outer periphery of the variable power lens frame 2, and a movable ring is provided in the compensation lens frame 3. The distal end portion passes through the elongated hole 3a (see FIG. 2) and the guide elongated hole 7a (see FIG. 2) in the yt-axis direction drilled in the fixed frame 7, and the tip portion is drilled into the zoom operation frame 9. The elongated hole 9a (
(see Fig. 2), and a variable magnification moving lens 12 fitted in the compensation lens frame 3, which is erected on the outer periphery of the compensation lens frame 3, and a fixed frame 7.
The main part thereof is composed of a compensating cam pin 13 fitted into a compensating cam elongated hole 7b (see FIG. 2) drilled in the compensating cam pin 13.

The focus lens frame 1 is a double cylindrical body in which a large-diameter cylinder and a small-diameter cylinder are integrated by a front wall, and the focus lens group I is fitted and held inside the small-diameter cylinder. At the same time, a helicoidal male thread 1a is threaded on the outer periphery of the small diameter cylinder. This helicoid male thread 1a is a helicoid female thread 7 threaded on the inner circumferential surface of the distal end of the fixed frame 7.
d, and the focus lens frame 1 is screwed to the fixed frame 7.
It is designed to be able to move forward and backward in the direction of the original axis while rotating against it. Further, a rotation transmission pin 14 is installed on the outer periphery of the rear end of the large diameter cylinder of the focus lens frame 1, and this rotation transmission pin 14 is bored in the distance adjustment ring 11 in the optical axis direction. It is fitted into a long hole 11a (see FIG. 3) for play in the optical axis direction.

The variable power lens frame 2 is formed of a short cylindrical body, and the variable power lens group (2) is fitted and held on the inside thereof, and the variable power moving pin 12 is mounted on the outer periphery as described above. It is planted. The moving elongated hole 3a of the compensation lens frame 3 through which the variable magnification moving beam 12 passes is formed as a linear elongated hole forming a lead angle θ with respect to the optical axis direction, as shown in FIG. Similarly, the guiding elongated hole 7a of the fixed frame 7, through which the variable magnification moving pin 12 passes, is formed as a linear elongated hole along the original axis direction. Further, the rotational direction play slot 9a of the zoom operation frame 9 into which the magnification change movement pin 12 is fitted is formed as a circumferential slot that is perpendicular to the optical axis direction.

The compensation lens frame 3 is formed of a cylindrical body having a circularly projecting edge at its rear end, and the compensation lens group 1 is fitted and held inside the inwardly projecting edge. As described above, this compensating lens frame 3 has a long hole 3a for movement, and a compensating cam bin 13 is installed on the outer periphery of the long hole 3a. As shown in FIG. 2, the compensating cam elongated hole 7b of the fixed frame 7 into which the compensating cam bin 13 is fitted is formed in an arcuate shape that curves toward the rear of the base shaft.

The relay lens frame 4 is formed of a cylindrical body that is fitted inside the support frame 6, and the relay lens group (2) is fitted and held in the middle inside of the frame. A focal position adjustment screw 15 is screwed into this relay lens frame 4 through a focal position adjustment long hole 6a drilled in the support frame 6 in the direction of the original axis, and by tightening the screw 15, The relay lens frame 4 is integrated with the support frame 6. The above support frame 6e.

It is fixed to the mount member 5 with screws 16, and the fixed frame 7 is fixed to the support frame 6 with screws 17. An index ring 18 is fixed to the fixed frame 7 with screws 19 on the inside of the front end of the diaphragm ring 8 disposed on the outer periphery of the rear end of the fixed frame 7. A ring 20 is screwed on. This decorative ring 20 is a driver insertion hole 7C for focal position adjustment bored in the fixed frame 7.
It serves to prevent dirt and dust from entering the zoom lens barrel. Driver insertion hole 7C is
Needless to say, it is bored so as to face the focal position adjusting screw 15 and the elongated hole 6a.

The zoom operation frame 9 has a long hole 9a for play in the rotational direction.
In addition, a regulating groove 9b for regulating the rotational and sliding range of the surrounding frame 9 is provided on the inner surface thereof. This regulating groove 9b is formed wide, and the concave groove 9b
A stopper pin 21 erected in the middle of the outer periphery of the fixed frame 7 is fitted inside.

The operating range of the zoom operation frame 9 is regulated by the stopper 9C formed by the inner peripheral surface of the regulation groove 9b and the stopper pinot 21. Further, the distance adjustment ring 11 is fixed to the zoom operation frame 9 by screws 22, and a rubber ring 23 for operation is tightly fitted around the outer periphery of the distance adjustment ring 11.

As described above, the conventional four-group zoom lens barrel is configured, and in this zoom lens barrel, distance adjustment operations and zooming operations are performed as follows.

First, to perform the distance dividing section, the distance adjusting ring 11 is rotated via the rubber ring 23. Then, the focus lens frame 1 rotates together with the distance adjustment ring 11 via the elongated hole 11a and the rotation transmission pin 14, and the focus lens frame 1 is rotated and moved back and forth in the original axis direction by the helicoid male screw 1a and the female screw 7d. . Therefore, focus lens group I
is moved in the 'li-optical axis direction between the two-dot chain line and the solid line in FIG. 4, and the photographing distance is adjusted. Note that when the distance adjustment ring 110 rotates, the zoom operation frame 9 also rotates together, but since the elongated hole 9a is bored in a direction perpendicular to the original axis, the magnification change movement pin 12 does not move.

-! In addition, to perform zooming, the distance adjustment ring 11 is moved in the optical axis direction via the rubber ring 23. Then, the zoom operation frame 9 also slides in the direction of the base axis together with the distance adjustment ring 11, and the magnification movement bin 12 is guided by the long hole 7a of the fixed frame 7 through the long hole 9a, move in the direction. Therefore, when the variable power lens frame 2 is advanced or retreated in the direction of the X-axis, the compensation lens frame 3 is rotated by force through the long hole 3a for movement, which forms an angle θ with the long hole 7a. . During this rotation, the movement path of the compensation lens frame 3 is restricted by the compensation cam bin 13 and the cam elongated hole 7b.
The variable power lens frame 2 rotates while being moved non-linearly in the original axis direction with respect to the linear movement. Therefore, as shown in FIG. 4, the variable power lens group (■) and the compensation lens group (1) are arranged in a non-linear manner so that the focal position does not change even when the variable power lens group (H) moves linearly. Go to
Compensate for this. Therefore, zooming is performed. Note that when the distance adjustment ring 11 is moved in the direction of the original axis, the focus lens frame 1 does not rotate because the elongated hole 11a is formed in the direction of the optical axis.

In a 4-group zoom lens barrel, as shown in Figure 4, when the variable power lens group ■ is located at the frontmost position, the wide-angle state (see Figure 5) is at the rearmost position. A telephoto state (see FIG. 7) is obtained when the lens is positioned in the middle of these positions, and a standard state (see FIG. 6) is obtained when the lens is located between these positions. By the way, in any zoom state from the above-mentioned wide-angle state to the [desired] state by zooming, the focal position P is determined by the last relay lens group (2).

Needless to say, it is easy to move around.

By the way, in the conventional four-group zoom lens barrel described in [7] above, the positioning adjustment of the focal point P4 when assembling the lens barrel is performed by displacing the relay lens group (2) in the last group in the t-axis direction. It was like that. This adjustment method was performed on the premise that the light ray after passing through the compensation lens group ■ becomes afocal (see Figures 5 to 7). Tightening of the adjustment screw 15 within the elongated hole 6a (this was done by changing the screw position).

However, the conventional 4 that adopts this adjustment method
In a group type zoom lens barrel, in order to loosen or tighten the screw 15 from the outside of the lens barrel, it is necessary to drill a through hole 7C in the fixed frame 7 for inserting a screwdriver. In order to prevent dirt and dust from entering through the through hole 7C, there is a drawback that it is necessary to specially provide a decorative υ ring 20 to cover the through hole 7C. In addition, it is necessary to hold the relay lens frame 4 fitted to the support frame 6 just for adjustment during assembly, which has the disadvantage that the number of parts increases and the positioning accuracy of the relay lens group (2) decreases. .

Also, unlike the upper 4-group zoom lens barrel, some conventional 4-group zoom lens barrels have the positioning adjustment of the focal position P4 for all 4 lens groups in the C-axis direction. Some are designed to do this by moving back and forth.

Specifically, this adjustment method is used to move the lens frame that holds the entire lens group relative to the mount member or a fixed frame fixed to the same member. If the cargo frame and tail 1□i' had to be made separately, there was a drawback that extra large parts would be required. For the frame and all the multiple openings, it is necessary to add the same number as υ, so we drilled several holes for inserting the doji bar in the one-leg frame, and also drilled these H holes in ?L((( ') had the disadvantage of having to provide a decorative ring for the lens frame.Furthermore, if an external force is applied to the mirror frame, there is a possibility that the frame will shift and the adjustment will be disrupted. It had the disadvantage of being strong.

Furthermore, in conventional 4-group zoom lens barrels, a spacer made of a washer, ring, etc. is inserted between the mount system or a member fixed thereto and the fixed frame that holds the entire lens group. There is also a system in which the entire lens group is shifted in the direction of the original axis, thereby adjusting the position of the focal point P4.

In conventional 4-group zoom lens barrels that use the A alignment method, it is not possible to adjust the collimator while looking at it, so processes such as measurement and damage are required during assembly, which takes a lot of man-hours. There were drawbacks. Furthermore, since only step-by-step adjustments can be made, highly accurate positioning is rarely possible.

In view of the above-mentioned points, an object of the present invention is to provide an adjustment means that allows a compensation lens group to be moved in the direction of the original axis independently of other lens groups, and to adjust the position of the focal point by this adjustment means. To provide a four-group zoom lens barrel configured to perform the following functions.

Hereinafter, the Kinoi U3A will be explained based on the illustrated embodiment.

First, before entering into a detailed description of the embodiment, the possibility of adjusting the position of the focal point P4 by moving the compensation lens group l will be discussed.

Like the conventional four-group zoom lens barrel shown in FIG. 1 above, a normal four-group zoom lens barrel has a focus lens group 1. In most cases, a variable magnification lens group, a compensation lens group I, and a relay lens group (2) are sequentially arranged, so that the light beam after passing through the compensation lens group (2) becomes afocal. However, the condition that the light beam after passing through the compensation lens group 1 is afocal is not necessarily required, and the light beam after passing through the compensation lens group I11 is It is sufficient if the number of rays is set.

As mentioned above, the method for adjusting the focal position Pa in a conventional four-group zoom lens barrel is as follows:
Two methods have been adopted: a method in which the relay lens group (2) is moved back and forth in the direction of the original axis, and a method in which the entire lens group is moved back and forth in the direction of the original axis. In these adjustment methods, positioning adjustment of the focal position P4 and zooming focus movement adjustment can be performed independently. It has advantages such as being able to adjust the aperture diameter independently, but from an optical perspective, by adjusting the focal position, ■ focal length does not change, ■ zooming focus does not shift, ■ The fact that the F number does not change means that nine conditions are satisfied.

Therefore, even if both of the above adjustment methods are not used, any adjustment method that satisfies the conditions (■) to (■) above will have the same advantages and can be adopted as a new adjustment method in place of the conventional adjustment method. It can be said that it is possible.

Therefore, we will specifically examine whether or not the method for positioning and adjusting the focal position by moving the compensation lens group l adopted in the four-group zoom lens barrel of the present invention satisfies the conditions (■) to (■) above. do.

In examining whether the method of positioning and adjusting the focal position by moving the compensation lens group (2) satisfies the conditions (1) to (2) above, a system as shown in FIG. 8 will be considered as a model. In this system, the 'yt line after passing through the compensation lens group 1 is afocal, and the image point P of the variable magnification lens group 4 lens group is the front focal point F of the compensation lens group I. Since they match, the rays emitted from the object point P2 for the compensation lens group ■ are refracted by the same lens group l and become parallel to the original axis, as if there were an image point P by the compensation lens group I at infinity. The state is as follows, and the light ray coming out from the object point P to the relay lens group ■ is refracted by the same lens group ■,
An image point P4 is generated at the rear focal point F'4 of the lens group (2).

Now, from the above afocal thread state, focus position P4
Adjustment movement amount Δ of compensation lens group l to adjust the position of
Suppose that the ridge is retreated in the direction of the original axis.

Then, the compensation lens group ■ moves to the position (I), and the front focal point F3 and rear focal point F6 of the same lens 91 move to the positions (F3) and (Fri), respectively. Since the position of the object point P2 remains unchanged, in order to find the position of the image point (P3) due to the movement of the compensation lens group
The distance between object points p and i using F as a reference is xl r image point (
If the distance to P3) is x3', it is %x3-Δ, so from Newton's formula, it becomes. However, fll indicates the focal length of the -fil compensating lens l. Next, the object point (P
When determining the position of 3), the distance x4 from the front focal point F4 to the object point is determined by using the above equation (1): x, = f, + f, -D + Δ10X! =f3+f, -D+Δ+”s/Δ・・・・・・・・・
...(2) becomes. However, D is the principal point distance between the compensation lens 2% M and the relay lens group ■ in the afocal state.

f4 is the focal length of relay lens group (2). Next, find the position of the image point (P4) with respect to the relay lens group ■.
Since the distance x7 from the rear focal point F2 to the image point (P4) is equal to the amount of deviation d of the image point position, using the above equation (2),
According to Newton's formula, pl -f electric -fmeng d= == □ X, f, + f, -1)+Δ+'s/Δ.

However, since the adjustment movement amount Δ was small, the first-order term was ignored.

Next, by moving the compensation lens group I, the compensation lens rNl
We will investigate how much the imaging magnification β changes depending on the relay lens group ■ and the relay lens group ■. This imaging magnification β is the product of the magnification by the compensation lens lf:ill and the magnification by the relay lens group ■, so using the above equation (2), (f, + f4-1)) Δ + Δ2 + 11 ~ -f, f.

(f3+14 D)Δ114 tonal. However, since the adjustment movement amount Δ was small, the quadratic term was ignored. The value in parentheses in the above equation (4) represents the variation ratio α of the imaging magnification β when the compensator lens group 111 is moved.

Next, we will examine how much the axial ray height during compensation lens decomposition changes due to the movement of the compensation lens group. If the rear numerical apertures N, A, of the relay lens group (2) are set to N, A, 0 when the object point is at infinity, then the axial ray height h4 of the relay lens group (2) before adjustment is given. The axial ray height J when the compensating lens disintegration is moved by the adjustment movement amount Δ is hl4-(f4+d)xN, since securing N, A, and 0 satisfies the condition that the F number is constant. , A, 0 ・・・・・・・・・
...song...(7). Therefore, the axial ray height h in the compensation lens group (2) is as follows: Bow=N, A, 0X(f4+d)+(D-Δ). The second term of the above equation (8) is the difference between the axial ray high bow and hl, and can be obtained relatively easily from a proportional equation using the similarity relationship between triangles. On the other hand, the axial ray height h1 before adjustment in the compensation lens group ■ is the axial ray height h1 before adjustment in the relay lens group ■.
4, the variation ratio r of the axial ray height h3 is given by the above (
8) Divide both sides of the equation by both sides of (6) above and sort it out, we get the following. However, since Δ is small, the quadratic term was ignored.

The amount of deviation d of the image point position determined by the above formula (3) is related to the zooming focus movement under the above condition Φ), and the imaging magnification β determined by the above formula 4 is related to the above condition Φ). is related to changes in focal length. Further, the variation ratio r of the axial ray height h3 determined by the above equation (9) is related to the change in the F number of the above condition (2).

As you can see from the above equations (3), (4), and (9), each equation includes the principal point spacing, and this principal point spacing is an amount that changes due to zooming. Basically, each of the conditions (1) to (2) above are not satisfied.

However, in reality, the amount of deviation d due to changes in the spacing between principal points,
The problem is the degree of change in the imaging magnification β and the variation ratio r,
If these changes are sufficiently small, positioning adjustment of the focal position by moving the compensating lens de-weighting should be able to be put to practical use.

Therefore, using specific numerical values, we next examine how much the shift amount d, the imaging magnification β, and the variation ratio γ change as the principal point interval changes. In addition, below, subscripts W, S, T
indicates the values for wide, standard, and telephoto conditions.

Now, the focal length f of the compensation lens group l is t-101,77
7, the focal length f of the relay lens group ■ is 110,65
3 m, and the adjustment movement amount Δ of the compensation lens group l is 0.7 W. In addition, the principal point spacing DW, Da, and Dl in each of the wide, standard, and telephoto states are -22J915, respectively.
Parrot, −32,105ss and −22,875 yang. Note that the principal point spacing pw, DS, and D tube have negative values because the front principal point of the relay lens group (2) is located in front of the rear principal point of the compensation lens group I. Further, it is assumed that the zooming focus movement has already been achieved. From the above 6 values.

f, +f4-Dw=235.34 FMIIB.

fs+f4-D5=244.5a5ttn.

r3+f4- DT= 235.305m, so
When calculated by substituting into the above equation (3), the adjustment amounts dw, ds, and dT of the focal position P4 in each of the wide, standard, and telephoto states are as follows: dw=-0,81446ya ds=-"0.81397B dT= -0,81446 intestines.

Therefore, if the compensation lens group ■ is moved by about Δ=±0.7s and the focal point position P4 is adjusted by about d=+0.8W, the zooming focus movement will be about 0.001m, which is no problem in practice. . Therefore, the above condition (2) is satisfied.

Next, looking at the amount of change in the imaging magnification β due to the same adjustment, we find that
By substituting 6 values into the above equation (4), βW−1,070
19 β5=-1,06954 βT=-1.07019. Imaging magnification β='4/'s before adjustment is 1.08
721 seagull, the variation ratio α in equation (5) above is αW
=0.98434 αS=0.98375 αT=0.98434. Therefore, if the variation ratio α is large, the focal length will increase or decrease by about 1.6%.

Therefore, due to the movement of the compensation lens group, the focal position P4 can be changed to d
= o, s When the adjustment is made by about s m, this causes a variation of about ±1.6% in the focal length, but such a variation poses no practical problem, and the condition (2) above is satisfied.

Next, the fluctuation of the axial ray height h3 to maintain a constant F number by similar adjustment will be investigated. In the above formula (9), 1 + d/f = 0.99264, so the variation ratio r of the axial ray height is W = 0.9
9112°rS=0.99051.

γT=Q, 99112. Therefore, the axial ray height h3 changes by about ±0.9% at the principal point position of the compensation lens group I. However, since the change in focal length is included in equation (9) above, it can be considered that only the F number changes by this amount.

Therefore, by moving the compensation lens group I, the focal position P4 can be changed to d.
When adjusted by -±0.8 m, the height of the axial ray at the principal point position of the compensation lens group ■ becomes +''
It changes by about 0.9 inches. This means that if the diaphragm that passes the afocal light rays is used as is, the F number will change by about 0.9 inches. A change of about :i:0.9% in the F number does not cause any practical problems.
Condition (2) above is also satisfied.

As described above, even if the focal position P4 is adjusted by moving the compensation lens group l (7), as long as the amount of adjustment d falls within a certain small range, no problem will arise in practice. Substantially each of the conditions (1) to (4) above are satisfied. Therefore, it is possible to position the focal position P4 and clean up the debris by moving the compensation lens.

Next, the focus position P4 due to the movement of the compensation lens group controller described above is
Based on the conclusion that the position adjustment is possible, we will now explain a specific embodiment of the four-group zoom lens barrel of the present invention. Fig. 9 shows an embodiment of the present invention. It shows a group type zoom lens barrel. This four-group zoom lens barrel differs from the conventional zoom lens barrel shown in FIG.
The main differences are that the compensating cam bin 13 is replaced with a compensating cam member 31 having adjustment means, and that the relay lens frame 4 and support frame 6 are replaced with an integrated relay lens frame 32.

As shown in FIGS. 10 and 11, the compensating cam member 31 is formed of a short cylindrical body having a long adjustment hole 31a' (z) in the center, and has a dish-shaped concave upper surface. At the same time, the left and right sides of the lower surface portion are cut to provide adjustment guide protrusions 31b.As shown in FIGS. A compensating cam elongated hole 7 is fitted into an adjusting elongated groove 3b formed in the compensating lens frame 3 and is formed in the fixed frame 7.
It is stored in b.

The fixing screw 33 is fixed to the compensating lens frame 3 by passing through the adjusting hole 31a and being screwed into the screw hole 3C screwed into the compensating lens frame 3. Like the moved long hole 3a, the long groove 3b is bored 7 so as to have a lead angle θ with respect to the original axis direction, and the screw hole 3C is threaded in the center thereof. Therefore, with the screw 33 loosened, the compensating cam member 31 can slide in the direction of the lead angle θ while being guided by the guide protrusion 31b and the long groove 3b, so that it can be moved to an appropriate sliding position. By tightening the screw 33, it is fixed to the compensation lens frame 3. Note that the lead angle θ' of the first adjustment long groove 3b is in the same direction as the moved long hole 3a.
The compensating cam elongated hole 7b is drilled in the direction of
This is to prevent the starting point, intermediate point, and ending point of the compensating cam member 31 from changing even when the cam member 31 is adjusted.

The relay lens frame 32 is formed of a two-stage cylindrical body in which a front small-diameter cylinder part and a rear large-diameter cylinder part are integrated, and the relay lens group (2) is fixed in the front small-diameter cylinder part. , the rear large-diameter cylindrical portion is fixed to the mount member 5 with screws 16. Therefore, the zoom lens barrel of this embodiment is not provided with the adjusting screw 15 and the long hole 6a that were provided in the conventional zoom lens barrel shown in FIG. Index ring 18 and decoration 9 ring 2
0. Also, no through hole 7C or the like is provided.

Note that other members not specifically mentioned have the same structure as the corresponding members of the conventional zoom lens barrel shown in FIG. The detailed explanation will be omitted in 1.

In the 4-group zoom lens barrel of this embodiment configured as described above, in order to adjust the focal position, for example, from the wide-angle state, loosen the screw 33 and tighten the compensation cam member 3.
1 is slid over the long groove 3b, and the compensation lens frame 3 is rotated back and forth to keep the position of the cam member 31 in the cam long hole 7b at the wide position. Then, when the focal position is positioned at a predetermined position by the collimator and the following is confirmed, the screw 33 is tightened to fix the cam member 31 to the compensation lens frame 3.

In this way, for example, the positional relationship between the variable power lens group ■ and the compensation lens group ■ in the wide-angle state is uniquely determined, and the light rays after passing through the compensation lens group ■ may deviate from the afocal state. , accurate focal position positioning is performed.

The operations during distance adjustment and zooming after adjusting the focus position are the same as those for the conventional zoom lens barrel shown in Fig. 1 above, so the detailed operations are as follows. The explanation will be omitted to the strings.

FIG. 14 shows a modification of the focal position adjusting means in the 4# type zoom lens barrel of the embodiment shown in FIGS. 9 to 13 above. The compensating cam member 34 in this adjustment means is formed of a thick disc body having a screw hole or a through hole 34a in the center.
By passing through 4a i and screwing the fixing screw 33 into the adjustment slot 3d drilled in the compensation lens frame 3,
It is fixed to the compensation lens frame 3. The elongated hole 3d is formed to be slightly narrower than the diameter of the threaded portion of the screw 33,
Like the long groove 3b, it is bored so as to form a lead angle θ with respect to the original axis direction. The screw 33 is screwed into and fixed in a predetermined position of the elongated hole 3d in a tap-tight manner.

Even with the adjusting means configured in this way, the cam member 3
4 can be moved in the direction of the lead angle θ, so
The focal position can be adjusted in the same manner as the adjusting means in the zoom lens barrel shown in FIGS. 9 to 13 above.

FIG. 15 shows another embodiment of the invention.

The four-group zoom lens barrel of this embodiment has a compensation lens frame 3 in the conventional zoom lens barrel shown in FIG.
A long hole 35a for moving is bored, and the compensation cam pin 1
The lens is divided into a cam frame 35 on which the lens 3 is planted, and a holding frame 36 that is fitted into the cam frame 35 and supports the compensation lens group I.
A means for guiding both frames 35 and 36 in the direction of the original axis and an eccentric pin 3
7, the focal position can be adjusted.

The long hole 35a for movement is the long hole 3 shown in FIG.
Similarly to a, the hole 35a is bored at an angle of 0 with respect to the optical axis direction, and the magnification movement pin 12 is passed through the elongated hole 35a. Further, the guide means in the direction of the base axis is installed in a long guide hole 35b bored in the cam frame 35 overflowing in the direction of the base axis, and in the holding frame 36,
It is formed by a guide pin 38 that fits into the guide elongated hole 35b.

The eccentric pin 37 has a head 37 as shown in FIG.
The threaded portion 37b is provided eccentrically with respect to a,
The screw portion 37b is screwed into the screw hole 36a of the holding frame 36, and the head 37a is arranged so as to be rotatable (the first
(See Figure 7). The head 37a is fitted into a regulating hole 35C formed in the five-cam frame 35 along the circumferential direction.

Note that also in the 4W zoom lens barrel of this example,
Since the relay lens frame 4 and the support frame 6 in the conventional zoom lens barrel shown in FIG. 1 are replaced with the integrated relay lens frame 32,
As in the case of the zoom lens barrel of the 7'C embodiment shown in FIG. No decorative ring 20 or the like is provided.

In order to adjust the focus position in the four-group zoom lens barrel of this embodiment configured as described above, the eccentric pin 37 is rotated to swing the head 37a relative to the threaded portion 37b. Then, since the head 37a is fitted into the circumferential regulating elongated hole 358, the support frame 36 is guided by the elongated guide hole 35b and the guide pin 38, and is aligned with respect to the cam frame 35 in the optical axis direction. Displaced to. Therefore, the rotation of the eccentric bin 370 is stopped when the focus position is positioned at a predetermined position while looking at the collimator.

In this way, the positional relationship between the variable magnification lens group (2) and the compensation lens group (2) is uniquely determined, and accurate focal position positioning adjustment is performed.

The operations during distance adjustment and zooming after adjusting the focus position are the same as those of the conventional zoom lens barrel shown in FIG. 1 above.

As described above, according to the present invention, since the focal position is adjusted by moving the compensation lens group in the original axis direction, the relay lens frame can be connected to the mount frame or the frame fixed thereto. Since it can be integrally formed, the number of parts can be reduced and the positioning accuracy of the relay lens group can be improved.

In addition, since there is no need for a screw for adjusting the position of the relay lens frame, there is no need for a through hole in the fixed frame that is required to rotate this screw, and there is no need for a decorative ring to cover the through hole. Become. Therefore, the number of parts can be further reduced.

Furthermore, since continuous adjustments can be made while looking at the collimator, highly accurate adjustments can be made with less man-hours.

Furthermore, since the adjustment is made by moving the originally movable compensation lens group inside the cylinder, the means added for adjustment is simple, and even after adjustment, there is no fear that the adjustment will be disturbed by external force.

Therefore, it is possible to provide a four-group zoom lens barrel that eliminates the conventional drawbacks mentioned in the specification and is extremely convenient to manufacture.

[Brief explanation of drawings]

FIG. 1 is an upper half sectional view showing an example of a conventional 4-group zoom lens barrel, and FIGS. 2 and 3 show various cams in the 4-group zoom lens barrel shown in FIG. 1 above. FIG. 4 is an enlarged plan view of the main parts showing the positional relationship between the two; FIG. 4 is a line diagram showing the operational positional relationship of each lens group in the four-group zoom lens barrel shown in FIG. The figure is a route diagram showing the appearance of light rays in each of the wide, standard, and telephoto states in the four-group zoom lens barrel shown in Fig. 1 above. FIG. 9 is a route diagram for explaining the method of positioning and adjusting the focal position by moving the compensation lens group, which is adopted in the lens barrel. Half sectional view. FIGS. 10 and 11 are an enlarged plan view and an enlarged side view showing a cam member as a means for adjusting, which is disposed in the four-group zoom lens barrel shown in FIG. WJ9 above, and FIG. 12 is an enlarged side view. , an enlarged sectional view of the main part showing the A14,=2@ means in the four-group zoom lens barrel shown in FIG. 9 above, and FIG. 13 is an enlarged plan view of the main part of the adjustment means shown in FIG. 12 above. , FIG. 14 is an enlarged cross-sectional view of a main part showing a modification of the adjusting means shown in FIG. 12, and FIG. 15 is an upper half of a four-group zoom lens barrel showing another embodiment of the present invention. 16 is an enlarged plan view showing an eccentric pin as an adjustment means disposed in the four-group zoom lens barrel shown in FIG. 15, and FIG. 17 is a sectional view of part I. FIG. 2 is an enlarged cross-sectional view of a main part showing a field adjustment means in the four-group zoom lens barrel shown in the figure.

Claims (1)

[Claims] In a 4-group zoom lens 6-trillion lens having four lens groups: a focus lens i+v, a variable power lens group, a compensation lens group, and a relay lens group, the compensation lens group is A four-group zoom lens barrel, characterized in that it is provided with an adjustment means that is movable in the axial direction, and the focal position can be adjusted by this adjustment means.